ArticlePDF Available

Abstract

The human cardiovascular diving response has been shown to have an oxygen-conserving effect during simulated breath-hold diving by apnoea with face immersion. However, it is not known if facial immersion enhances the response to the same extent as that in the diver with the body immersed and if this leads to oxygen conservation. Seventeen subjects each completed a total of 12 apnoeas of fixed, near-maximal duration. Four series of three apnoeas were conducted: dry body with apnoea (DA), dry body with face-immersion apnoea (DFIA), immersed body with apnoea (IA), and immersed body with face-immersion apnoea (IFIA). Air and water temperatures were 23 degrees Celcius. Heart rate, skin blood flow, arterial blood pressure, arterial haemoglobin saturation, lung volume and end-tidal fractions of carbon dioxide and oxygen were recorded non-invasively. Face immersion led to a greater reduction in heart rate during apnoea, regardless of body immersion (DA-DFIA 9.3%, 95% confidence interval (CI) 3.54, 0.1; IF-IFIA 7.9%, 95% CI 4.8, 0.2). Both DFIA and DA resulted in skin vasoconstriction, which was more pronounced during DFIA (16%, 95% CI 8.4, 0.3). During body immersion, skin vasoconstriction was reduced considerably, and neither IA nor IFIA reduced blood flow further. Mean arterial pressure increased more in the immersed condition than on dry land. Arterial saturation remained higher after DFIA (0.4%, 95% CI 0.2, 0.01) and IFIA (0.4%, 95% CI 0.4, 0.01) series, suggesting an oxygen-conserving effect of the more powerful diving response associated with face immersion. We conclude that the oxygen-conserving effect of the diving response in the immersed diver is the same as that observed in the dry, horizontal, simulated diving model.
9^k^c\VcY=neZgWVg^XBZY^X^cZKdajbZ(.Cd#)9ZXZbWZg'%%. &.(
@ZnldgYh
7gZVi]"]daYY^k^c\![gZZY^k^c\!Y^k^c\gZÅZm!^bbZgh^dc!kVhdXdchig^Xi^dc!dmn\ZcXdchjbei^dc
6WhigVXi
YZ7gj^_cG!G^X]VgYhdcB!HX]V\ViVn:#Dmn\Zc"XdchZgk^c\Z[[ZXid[i]ZY^k^c\gZhedchZ^ci]Z^bbZghZY]jbVc#9^k^c\
VcY=neZgWVg^XBZY^X^cZ#'%%.0(.)/&.(".#
>cigdYjXi^dc/I]Z ]jbVcXVgY^dkVhXjaVgY^k^c\ gZhedchZ]VhWZZch]dlcid ]VkZVc dmn\Zc"XdchZgk^c\Z[[ZXiYjg^c\
h^bjaViZYWgZVi]"]daYY^k^c\WnVecdZVl^i][VXZ^bbZgh^dc#=dlZkZg!^i^hcdi`cdlc^[[VX^Va^bbZgh^dcZc]VcXZhi]Z
gZhedchZidi]ZhVbZZmiZciVhi]Vi^ci]ZY^kZgl^i]i]ZWdYn^bbZghZYVcY^[i]^haZVYhiddmn\ZcXdchZgkVi^dc#
BZi]dYh/HZkZciZZchjW_ZXihZVX]XdbeaZiZYVidiVad[&'VecdZVhd[ÄmZY!cZVg"bVm^bVaYjgVi^dc#;djghZg^Zhd[i]gZZ
VecdZVhlZgZXdcYjXiZY/YgnWdYnl^i]VecdZV96!YgnWdYnl^i][VXZ"^bbZgh^dcVecdZV9;>6!^bbZghZYWdYnl^i]
VecdZV>6!VcY^bbZghZYWdYnl^i][VXZ"^bbZgh^dcVecdZV>;>6#6^gVcYlViZgiZbeZgVijgZhlZgZ'(D8#=ZVgigViZ!
h`^cWaddY Ådl!VgiZg^Va WaddYegZhhjgZ!VgiZg^Va]VZbd\adW^chVijgVi^dc!ajc\kdajbZVcYZcY"i^YVa[gVXi^dchd[XVgWdc
Y^dm^YZVcYdmn\ZclZgZgZXdgYZYcdc"^ckVh^kZan#
GZhjaih/;VXZ^bbZgh^dcaZYidV\gZViZggZYjXi^dc^c]ZVgigViZYjg^c\VecdZV!gZ\VgYaZhhd[WdYn^bbZgh^dc96·9;>6
.#(!.*XdcÄYZcXZ^ciZgkVa8> (#*)! %#&0 >;·>;>6 ,#.! .* 8>)#-!%#'#7di]9;>6VcY96 gZhjaiZY ^c h`^c
kVhdXdchig^Xi^dc!l]^X]lVhbdgZ egdcdjcXZY Yjg^c\ 9;>6 &+! .* 8>-#)!%#(#9jg^c\WdYn^bbZgh^dc!h`^c
kVhdXdchig^Xi^dclVhgZYjXZYXdch^YZgVWan!VcYcZ^i]Zg>6 cdg>;>6 gZYjXZYWaddYÅdl[jgi]Zg#BZVcVgiZg^VaegZhhjgZ
^cXgZVhZYbdgZ^ci]Z^bbZghZYXdcY^i^dci]VcdcYgnaVcY#6giZg^VahVijgVi^dcgZbV^cZY]^\]ZgV[iZg9;>6%#)!.*8>
%#'!%#%&VcY>;>6%#)!.*8>%#)!%#%&hZg^Zh!hj\\Zhi^c\Vcdmn\Zc"XdchZgk^c\Z[[ZXid[i]ZbdgZedlZg[jaY^k^c\
gZhedchZVhhdX^ViZYl^i][VXZ^bbZgh^dc#
8dcXajh^dc/LZXdcXajYZi]Vii]Zdmn\Zc"XdchZgk^c\Z[[ZXid[i]ZY^k^c\gZhedchZ^ci]Z^bbZghZYY^kZg^hi]ZhVbZVh
i]VidWhZgkZY^ci]ZYgn!]dg^odciVa!h^bjaViZYY^k^c\bdYZa#
Oxygen-conserving effect of the diving response in the immersed
human
Robert de Bruijn, Matt Richardson and Erika Schagatay
>cigdYjXi^dc
7gZVi]"]daYY^k^c\![gdb]ZgZdc gZ[ZggZY id Vh Y^k^c\!
aZVYhidV hZg^Zh d[XVgY^dkVhXjaVgVY_jhibZcihXVaaZY i]Z
»Y^k^c\gZhedchZ¼#I]Z bdhi egdcdjcXZY VY_jhibZcih VgZ
WgVYnXVgY^VVcYhZaZXi^kZeZg^e]ZgVa kVhdXdchig^Xi^dc#&!'
I]ZcZjgVahi^bja^^c^i^Vi^c\i]ZY^k^c\gZhedchZVgZYZg^kZY
Wdi][gdbi]ZVecdZVVcY[gdbhi^bjaVi^dcd[[VX^VaXdaY"
gZXZeidgh!Z#\#!Wn^bbZgh^dc#(!)BdhihijY^Zhd[ ]jbVc
Y^k^c\VW^a^i^ZhVcYVhhdX^ViZYgZÅZmZh]VkZWZZcWVhZYdc
aVWdgVidgnhijY^Zh!Vaadl^c\VXdcigdaaZYZck^gdcbZciVcY
VYkVcXZYiZX]c^fjZh#6bdYZajhZYWnbVcnaVWdgVidg^Zhid
h^bjaViZY^k^c\^hVecdZVl^i][VXZ^bbZgh^dc#)!*HijY^Zh
l^i]i]ZegdcZhjW_ZXi eZg[dgb^c\ VecdZVhl^i]i]Z[VXZ
Z^i]Zg^bbZghZYdg^cV^g!^#Z#!XVjh^c\VbdgZdg aZhh
egdcdjcXZYY^k^c\gZhedchZ!]VkZgZkZVaZYi]Vii]ZY^k^c\
gZhedchZ]VhVcVecdZV"egdadc\^c\Z[[ZXiVcYi]Vii]ZVgiZg^Va
dmn\ZcD'hidgZ^hXdchZgkZYYjg^c\VecdZVWdi]Yjg^c\
gZhiVcYZmZgX^hZ#+-Dmn\Zc XdchZgkVi^dcgZhjaih[gdbV
gZYjXZYWaddYÅdl^ci^hhjZhidaZgVciid]nedm^VVcYadlZg
bndXVgY^VaD'Xdchjbei^dcYjg^c\WgVYnXVgY^VVcYaZVYh
idVhadlZgD'YZeaZi^dc^ci]Zajc\h#.&&
I]Z^beVXid[[VXZ^bbZgh^dcYZeZcYhdci]ZiZbeZgVijgZ
Y^[[ZgZcXZWZilZZci]Zh`^cVcYi]ZlViZg#*>cVcVijgVaY^k^c\
h^ijVi^dc!]dlZkZg!i]ZY^kZg¼hZci^gZWdYn^hd[iZcXdchiVcian
^bbZghZY^cXddalViZg!^cVYY^i^dcidi]Z[VXZ^bbZgh^dc
dXXjgg^c\Yjg^c\i]ZVecdZVh#8dbeVg^hdchd[]ZVgi gViZ
gZhedchZh]VkZWZZcbVYZWZilZZc]dg^odciVaVecdZVh^c
V^gVcYlVgblViZgVi()D8#&'!&(I]Z[gZZY^kZg^ciZbeZgViZ
gZ\^dchl^aaa^`ZanWZY^k^c\^clViZghd['%·'*D8l^i]i]Z
jhZd[V lZihj^i!VcYl^i]i]Z [VXZjcXdkZgZY#6Xdda^c\
d[i]ZWdYnl^aagZhjai^cVXdaY"^cYjXZYkVhdXdchig^Xi^dc!
l]^X]bVn]VkZVcZ\Vi^kZZ[[ZXidci]ZY^k^c\gZhedchZ
VcYedhh^WanVWda^h]D'XdchZgkVi^dc#HiZgWVVcYAjcY\gZc
h]dlZYi]Vi!XdbeVgZYidWgZVi]"]daY^c\l]^aZh^ii^c\^cV^g!
h^bjaiVcZdjhkZgi^XVaWdYnVcY[VXZ^bbZgh^dc^cXdaYlViZg
'%D8gZYjXZYWgZVi]"]daY^c\i^bZXdch^YZgVWanWjilVh
VXXdbeVc^ZYWnVhigdc\WgVYnXVgY^V!l]^aZWgZVi]"]daY^c\
^clVgblViZg(*D8aZc\i]ZcZYi]ZWgZVi]"]daY^c\i^bZ!
Wjil^i]djiWgVYnXVgY^V#&)I]ZnZmeaV^ci]ZhZgZhjaihWnVc
^cXgZVhZYbZiVWda^XgViZVcYgZhe^gVidgnYg^kZVi'%D8YjZ
idX]^aa^c\#EVjaZkh]dlZY i]Vi! Yjg^c\ Xdci^cjdjhWdYn
^bbZgh^dc!VecdZVl^i]dji[VX^Va^bbZgh^dcgZhjaiZY^cV
WgVYnXVgY^Vh^b^aVgidi]Vi[djcYl]^aZWgZVi]"]daY^c\l^i]
[VX^Va^bbZgh^dcl^i]i]ZWdYn^cV^g#&*=dlZkZg!cdY^gZXi
XdbeVg^hdclVhVaadlZYWZilZZc i]Z ildhi^bja^^ci]Vi
hijYn!Vhi]ZXdchiVci WdYn^bbZgh^dclVhYdcZ^c ''D8
lViZg!VcY[VX^Va^bbZgh^dc^c&*D8lViZg!Vh^ijVi^dca^`Zan
id^cYjXZVbdgZedlZg[jagZhedchZ#*
Dg^\^cVaVgi^XaZh
http://archive.rubicon-foundation.org
9^k^c\VcY=neZgWVg^XBZY^X^cZKdajbZ(.Cd#)9ZXZbWZg'%%.&.)
6c^ciZgZhi^c\dWhZgkVi^dcYjg^c\VecdZV VcY [VX^Va
^bbZgh^dc^c&%D8lViZg!^cXdbW^cVi^dcl^i]^bbZgh^dc
d[i]Z[dgZVgb^c&%D8lViZg! lVh i]Vii]ZWgVYnXVgY^V
[gdbi]ZY^k^c\gZhedchZ]VYeg^dg^indkZgi]ZiVX]nXVgY^X
gZhedchZ^cYjXZY[gdbi]ZVgbX]^aa^c\#&+I]^hheZV`h[dgV
bV^ciV^cZYgZhedchZl^i]WdYn^bbZgh^dc#=dlZkZg!^cVc
VagZVYnXddaZck^gdcbZcil^i]gZYjXZY[VX^VaiZbeZgVijgZ!
i]ZZ[[ZXihd[[VX^Va^bbZgh^dcbVnWZgZYjXZY!YZXgZVh^c\
i]ZgZhedchZbV\c^ijYZ#*;Zgg^\cdVcYVhhdX^ViZhdWhZgkZYV
Y^k^c\gZhedchZYjg^c\^bbZgh^dcVcYZmedhjgZid^cXgZVhZY
VbW^ZciegZhhjgZ!Wji^ih bV\c^ijYZlVhcdiXdbeVgZYid
i]ZgZhedchZhd[i]ZhVbZ^cY^k^YjVah^cV^g#&,
I]jh!^i^hcdi`cdlcid l]Vi ZmiZci D'XdchZgkVi^dc
Veea^Zhidi]Z^bbZghZYY^kZg#I]ZegZhZcihijYn!i]ZgZ[dgZ!
^ckZhi^\ViZYi]ZYZkZadebZcid[i]ZY^k^c\gZhedchZ^ci]Z
^bbZghZY]jbVcl^i]VcYl^i]dji[VX^Va^bbZgh^dc!l^i]
heZX^ÄXgZ\VgYid^ihZ[[ZXidcD'XdchZgkVi^dc#
BZi]dYh
LZXdbeVgZYi]ZY^k^c\gZhedchZYjg^c\VecdZVh6VcY
[VXZ"^bbZgh^dcVecdZVh;>6d[i]ZhVbZ YjgVi^dc! ^c
]dg^odciVaYgn"WdYn9VcY^bbZghZY"WdYn>XdcY^i^dch!
gZheZXi^kZan#6Y^[[ZgZcXZ^cVgiZg^Va]VZbd\adW^chVijgVi^dc
V[iZgVecdZVVcY[VXZ"^bbZgh^dcVecdZVlVh jhZY Vh Vc
^cY^XVi^dcd[D'XdchZgkVi^dc#
HJ7?:8IH
HZkZciZZc]ZVai]nhjW_ZXih ( [ZbVaZh VcY &) bVaZh
kdajciZZgZY[dgi]Z hijYn#BZVcH9V\ZlVh '-#,,#(
nZVgh!]Z^\]i&,-#),#,Xb!lZ^\]i,,#)&%`\VcYbZVc
hiVcY^c\k^iVaXVeVX^inlVh )#.+%#.A#;djgiZZc d[i]Z
hjW_ZXih]VYhdbZeg^dgZmeZg^ZcXZ^cY^k^c\Wjicddc\d^c\
igV^c^c\!VcYi]gZZhjW_ZXihegVXi^hZYY^k^c\gZ\jaVganWji
l^i]VbVm^bjbd[ild]djgh eZg lZZ`# IldhjW_ZXih
hbd`ZYdXXVh^dcVaanVcYildlZgZhcj[[idWVXXdjhZgh#
:ME:G>B:CI6AEGD8:9JG:
I]ZhijYnXdbea^Zhl^i]i]Z=Zah^c`^9ZXaVgVi^dcVcYl^i]
HlZY^h]aVlhVcYZi]^XVahiVcYVgYh#6aahjW_ZXih h^\cZYV
XdchZci[dgbV[iZgWZ^c\[jaan^c[dgbZYd[i]ZZmeZg^bZciVa
egdidXda!l]^X]]VYWZZcVeegdkZYWni]ZgZ\^dcVa]jbVc
gZhZVgX]Zi]^XhWdVgYViJbZJc^kZgh^in#IdegZkZci
ZmXZhh^kZhigV^c!i]ZVecdZ^XYjgVi^dclVhhZi[dgZVX]hjW_ZXi
ViVeegdm^bViZan&*haZhhi]Vci]Z^g^cY^k^YjVabVm^bjb
WgZVi]"]daYi^bZ!WVhZYdcVh^c\aZegZ"ig^VabVm^bVaVecdZV
eZg[dgbZYl^i]dji]neZgkZci^aVi^dcdg[VX^Va^bbZgh^dc#
I]Zh]dgi"iZgbigV^c^c\ Z[[ZXidWhZgkZY l]ZceZg[dgb^c\
hZg^VaVecdZVh!^cXdbW^cVi^dcl^i]i]Zi^bZgZYjXi^dcWn
&*h!ldjaYi]jhZchjgZi]ViZVX]hjW_ZXiXdjaYeZg[dgbVaa
VecdZVhVii]ZhVbZ!egZYZiZgb^cZY!ÄmZYYjgVi^dc#&-I]Z
VkZgV\ZH9VecdZ^Xi^bZeZg[dgbZYYjg^c\i]ZZmeZg^bZcih
lVh*-&%h#I]ZZmeZg^bZcihXdch^hiZYd[&'VecdZVh^c
idiVa!Y^k^YZY^c[djgY^[[ZgZci hZg^Zh d[ i]gZZ hjXXZhh^kZ
VecdZVhheVXZY ildb^cjiZh VeVgi#7dYnXdcY^i^dchlZgZ
XdchiVciVXgdhhZVX]hZg^Zh!l]^aZ[VX^Va^bbZgh^dcgZ[Zgh
idVecdZ^XeZg^dYh#I]ZhZhZg^ZhlZgZ/
9gn"WdYnVecdZV96
9gn"WdYn[VXZ"^bbZgh^dcVecdZV9;>6
>bbZghZY"WdYnVecdZV>6
>bbZghZY"WdYn[VXZ"^bbZgh^dcVecdZV>;>6
Idb^c^b^oZdgYZgZ[[ZXih!i]ZXdcY^i^dch^ci]ZhZg^ZhlZgZ
VaiZgcViZYVcYi]ZhiVgi^c\h^ijVi^dchlZgZlZ^\]iZYWZilZZc
hjW_ZXih#I]ZX]d^XZlVhbVYZ id a^b^i i]Z VaiZgcVi^c\
hZfjZcXZhid[djg!i]jha^b^i^c\i]Zi^bZhVhjW_ZXicZZYZY
idX]Vc\ZdjiÄi#I]Z[djghZfjZcXZhjhZYlZgZVh[daadlh/
96!9;>6!>6!>;>6
9;>6!96!>;>6!>6
>6!>;>6!96!9;>6
>;>6!>6!9;>6!96
;dgi]Z[VXZVcYWdYn ^bbZgh^dch! bZVc H9 lViZg
iZbeZgVijgZlVh'(#&%#)D8!VcYi]ZbZVcV^giZbeZgVijgZ
lVh'(#(&#'D8#
K^iVaXVeVX^inK8lVhbZVhjgZY^ci]ZhiVcY^c\hjW_ZXiVi
i]ZhiVgid[VaaZmeZg^bZciVahZhh^dch!^ci]ZegdcZedh^i^dc
eg^dgid i]ZYgn"WdYnVecdZVh!VcY^ci]Z^bbZghZY"WdYn
XdcY^i^dceg^dgidi]ZhiVgid[i]Z^bbZghZY"WdYnVecdZVh#
>ci]ZYgn"WdYnhZg^Zh!hjW_ZXihlZgZdjiÄiiZYl^i]ecZjbVi^X
X]ZhiWZaadlhidYZiZXigZhe^gVidgnbdkZbZcihVcYVh`ZYid
;^\jgZ&
Edh^i^dcd[i]ZhjW_ZXiYjg^c\VecdZVh0YgnWdYnide!^bbZghZYWdYnWdiidb0hX]ZbVi^Xh]dlcd[VhZg^Zhd[
i]gZZVecdZVhl^i]^cY^XVi^dchd[Y^[[ZgZcieZg^dYhjhZY[dgVcVanhZh:E/Z[[ZXihd[edh^i^dc0G&·G(/gZ[ZgZcXZ
eZg^dYh[dgVecdZVh&·(0ild"b^cjiZgZhieZg^dYWZilZZcVecdZVh
http://archive.rubicon-foundation.org
9^k^c\VcY=neZgWVg^XBZY^X^cZKdajbZ(.Cd#)9ZXZbWZg'%%. &.*
a^Z^cVegdcZedh^i^dcdci]ZWZYl^i]i]Z]ZVYgZhi^c\dcV
e^aadldcVWdVgYXdkZg^c\VhbVaalViZgXdciV^cZg;^\jgZ
&#>ci]Z^bbZghZY"WdYnhZg^Zh!hjW_ZXihldgZ*bb[jaa
lZihj^ihl^i]i]Z X]ZhiWZaadlheaVXZY dcide#DcXZ^c V
egdcZ!ÅdVi^c\edh^i^dc!VWVglVheaVXZYVXgdhhi]ZiVc`^c
i]ZlViZgidhjeedgii]ZaZ\h!VcYVgZbdkVWaZ[dVbWdVgY
hjeedgiZYi]Z]ZVYd[i]ZhjW_ZXiWZilZZcVecdZVh#EgdWZh
[dgi]ZejahZdm^bZiZg!e]dideaZi]nhbdbZiZg VcY aVhZg"
9deeaZgÅdlbZiZglZgZ eaVXZY dc i]Z aZ[i]VcY!l]^X]
lVh`ZeiYgn#
>cVaahZg^Zhi]ZhjW_ZXihgZaVmZY[dgVb^c^bjbd[&%b^cjiZh
eg^dgidi]ZWZ\^cc^c\d[ZVX]VecdZVhZg^Zh#6iildb^cjiZh
WZ[dgZi]Z[^ghiVecdZVi]Z YViV gZXdgY^c\ XdbbZcXZY
VcYi]ZhjW_ZXilVhcdi^ÄZYd[ i]Z i^bZ gZbV^c^c\#6i
(%hWZ[dgZZVX]VecdZVVcdhZ Xa^elVheaVXZYVcYl^i]
&%hgZbV^c^c\VXdjciYdlcWZ\Vc VcY i]Z he^gdbZiZg
bdji]e^ZXZlVhd[[ZgZYidi]ZhjW_ZXi! l]dXdci^cjZYid
WgZVi]ZcdgbVaan VcYhiVgiZYi]ZVecdZVVii]ZZcYd[i]Z
XdjciYdlcV[iZgV[jaaZm]VaVi^dc[daadlZYWnVYZZe!Wjicdi
bVm^bVa!^c]VaVi^dc#I]Zbdji]e^ZXZlVhgZbdkZYYjg^c\
i]ZVecdZVh#HjW_ZXih lZgZcdi^ÄZYVWdjii]Z i^bZVii]Z
]Va["VecdZVed^ciVcYWnXdjciYdlc[dgi]ZaVhi&%h!VcY
ViVecdZViZgb^cVi^dci]ZnZm]VaZYXdbeaZiZani]gdj\]i]Z
bdji]e^ZXZ#I]jh!gZXdgY^c\hd[^che^gZYVcYZme^gZYajc\
kdajbZ!ZcY"i^YVa[gVXi^dcd[dmn\Zc;:ID'VcYZcY"i^YVa
[gVXi^dcd[ XVgWdcY^dm^YZ ;:I8D'lZgZ bVYZ#I]Z[VXZ
lVhYg^ZY^bbZY^ViZanV[iZgZVX]VecdZVVcYi]ZhjW_ZXi]VY
Vild"b^cjiZgZXdkZgneZg^dYWZilZZcVecdZVhd[VhZg^Zh#
GZXdgY^c\Xdci^cjZYi]gdj\]djijci^aildb^cjiZh V[iZg
ZVX]i]^gY VecdZV#6ii]Z ZcYd[ i]ZZmeZg^bZcih!\ZcZgVa
Xdb[dgilVhZkVajViZY[dgi]ZYgn"VcYi]Z^bbZghZY"WdYn
XdcY^i^dchjh^c\VhXVaZ[gdb&kZgnjcXdb[dgiVWaZid&%
kZgnXdb[dgiVWaZVcYVi]ZgbVaXdb[dgiZkVajVi^dcYjg^c\
^bbZgh^dcdcV hXVaZ [gdb&kZgnjcXdb[dgiVWaZid &%
kZgnXdb[dgiVWaZlVhbVYZ#
:FJ>EB:CI
K8!^che^gVidgnAK^cVcYZme^gVidgnkdajbZhAKZmelZgZ
bZVhjgZYjh^c\Vhe^gdbZiZgK^iVad\gVe]8dbeVXi>>!
7jX`^c\]Vb!:c\aVcY#6 8D'$D' VcVanhZg CdgbdXVe
Dmn!9ViZmD]bZYV!=Zah^c`^!;^caVcYlVhXdccZXiZYid
i]Zbdji]e^ZXZd[i]Zhe^gdbZiZgidbZVhjgZegZ"VcYedhi"
VecdZ^XZcY"i^YVa8D'VcYD'#=ZVgigViZ=GVcYVgiZg^Va
dmn\ZchVijgVi^dcHVD'lZgZbZVhjgZYXdci^cjdjhan!
l^i]i]ZVkZgV\^c\[jcXi^dchZidc+h!k^VejahZdm^bZign
7^dm(,%%Z!D]bZYV!BVY^hdc!JH6#BZVcVgiZg^Va
egZhhjgZB6E lVhbZVhjgZYjh^c\VcVjidbViZYÄc\Zg
e]dideaZi]nhbdbZiZg;^cVegZh'(%%!D]bZYV!BVY^hdc!
JH6#H`^cWaddY[adlH`7; lVh bZVhjgZY jh^c\ V
aVhZg"9deeaZgÅdlbZiZg 6YkVcXZ AVhZg ;adlbZiZg'&!
6YkVcXZ8dbeVcn!?VeVc# GZhe^gVidgnbdkZbZcihlZgZ
gZ\^hiZgZYl^i]aVWdgVidgn"YZkZadeZYecZjbVi^XX]Zhi
WZaadlhXdccZXiZYidVegZhhjgZhZchdg#6cVcVad\jZZkZci
bVg`ZgbVg`^c\i]ZVecdZ^Xi^bZ[gdbi]ZaVhi^che^gVi^dc
WZ[dgZidi]ZhiVgid[i]ZÄghiZme^gVi^dcV[iZgi]ZWgZVi]"]daY!
lVhhidgZYid\Zi]Zgl^i]di]ZgYViVjh^c\VYViVVXfj^h^i^dc
hnhiZbBE&%%6"8:!7^deVXHnhiZbh>cX!JH6#
96I66C6ANH>H
HjW_ZXihhZgkZYVhi]Z^gdlcXdcigda#IdhijYni]ZZ[[ZXid[
edh^i^dc!gZhi^c\kVajZhlZgZ dWiV^cZY[gdbV+%heZg^dY
hiVgi^c\V[iZg&%b^c^ci]Viedh^i^dc ;^\jgZ &# 8dcigda
kVajZh[dg=G!B6E!H`7;VcY HVD'lZgZ dWiV^cZY[gdb
i]ZeZg^dY.%(%hWZ[dgZZVX]VecdZV#8dci^cjdjh\gVe]h
[dgi]ZeZg^dY[gdb'*hWZ[dgZjci^a)%hV[iZgi]ZVecdZV
lZgZbVYZ[dg=G!B6EVcYHVD'WngZ"hVbea^c\iddWiV^c
VbZVckVajZ[dgZkZgn*h!VcYXVaXjaVi^c\gZaVi^kZX]Vc\Zh
[gdbi]ZXdcigdaiV`ZcWZ[dgZZVX] VecdZV# ;dg H`7;!
Xdci^cjdjh\gVe]hd[i]ZVWhdajiZYViVlZgZ jhZY! h^cXZ
XdcigdakVajZhlZgZkZgnY^[[ZgZciWZXVjhZd[XdaY"^cYjXZY
=G B6E H`7;HVD';
:ID' ;:I8D'
Web bb=\ baÇb^c"&Ç&%%\"&  egZVecdZV edhiVecdZV egZVecdZV edhiVecdZV
96 +. £&% &%%£&) *#-£, .,#) £& &+#' £%#. &'#*£& *#%£%#+ +#( £%#)
9;>6 ,% £- &%(£&& *#%£- .,#+ £& &+#' £%#. &'#)£' )#.£%#+ +#( £%#*
'96"9;>6"&#%£' "(#%£& %#.£%#* "%#' £%#' %#%&£%#& %#& £%#' %#%,£%#%, "%#%%(£%#%+
>6 ,) £&% .+£&( &#*£( .,#. £& &+#&£%#. &%#,£&#, )#.£%#+ +#+ £%#*
>;>6 ,* £&' .*£&) &#.£( .,#* £' &*#-£'#+ &&#*£&#- *#%£%#. +#+ £%#*
'>6">;>6 "%#+ £' %#. £)#& "%#) £%#* %#* £%#) %#) £%#( "%#, £%#' "%#&'£%#%. "%#%'£%#%)
9gnWdYn ,% £. &%&£&' *#)£, .,#* £& &+#'£%#. &'#)£&#* )#.£%#+ +#( £%#*
>bbZghZY ,) £&& .+£&( &#,£( .,#, £& &*#.£' &&#&£&#- *#%£%#- +#+ £%#*
'9gn"^bb ")#+£' *#* £)#* (#,£&#) "%#' £%#( %#' £%#' &#( £%#( "%#%'£%#& "%#(£%#%-
IVWaZ&
GZhi^c\kVajZhbZVc£H9d[]ZVgigViZ=G!bZVcVgiZg^VaWaddYegZhhjgZB6E!h`^cWaddYÅdlH`7;!
VgiZg^Vadmn\ZchVijgVi^dcHVD'!ZcY"i^YVa[gVXi^dcd[dmn\Zc;:ID'VcYXVgWdcY^dm^YZ;:I8D'[dgYgn"WdYn
VecdZV96!Ygn"WdYn[VXZ"^bbZgh^dcVecdZV9;>6!^bbZghZY"WdYnVecdZV>6VcY^bbZghZY"WdYn[VXZ"
^bbZgh^dcVecdZV>;>6!VcYi]ZeddaZYVkZgV\Zh[dgi]ZYgn"VcY^bbZghZY"WdYnXdcY^i^dch[dg&+hjW_ZXih
E1%#%&!E1%#%%&
http://archive.rubicon-foundation.org
9^k^c\VcY=neZgWVg^XBZY^X^cZKdajbZ(.Cd#)9ZXZbWZg'%%.&.+
kVhdXdchig^Xi^dcYjg^c\^bbZgh^dc#IdXdbeZchViZ[dgi]Z
Y^[[ZgZcXZ^cYjgVi^dcd[VecdZVhWZilZZchjW_ZXihi]ZÄghi
(%hVcYi]ZaVhi&*hd[i]ZVecdZVhlZgZVa^\cZY[dg=G!
B6EVcYH`7;!VcYHVD'lVhVa^\cZYl^i]i]ZZcYd[i]Z
VecdZVh#Id YZiZgb^cZ ^[ i]ZgZ lZgZ Y^[[ZgZcXZhWZilZZc
=G!B6E!VcYH`7;bZVhjgZbZcih!i]ZaVhi&*hd[VecdZVh
lZgZVcVanhZY#;dgYZiZgb^cVi^dcd[Y^[[ZgZcXZh^cHVD'V'%
heZg^dYi]ViZcXdbeVhhZYi]ZcVY^glVhVcVanhZY#
HI6I>HI>86A6C6ANH>H
9ViVlZgZ[jgi]ZgVcVanhZY[dgY^[[ZgZcXZhWZilZZc96
kZghjh9;>6!>6kZghjh>;>6 VcY i]Z eddaZY Ygn kZghjh
^bbZghZYXdcY^i^dch!VcYi]ZhZY^[[ZgZcXZhVgZ \^kZc
l]ZgZVeegdeg^ViZ!^cXajY^c\.*XdcÄYZcXZ^ciZgkVah
8>#8dbeVg^hdchWZilZZcVecdZVVcY[VXZ"^bbZgh^dc
VecdZV^cWdi]WdYn XdcY^i^dch!VcYWZilZZci]Z eddaZY
kVajZh[dgYgn"WdYn VcY ^bbZghZY"WdYn XdcY^i^dchlZgZ
VahdbVYZjh^c\'"h^YZYeV^gZYHijYZcii"iZhih#H^\c^ÄXVcXZ
lVhVXXZeiZYViE1%#%*#
GZhjaih
IZhi^c\d[dcZhjW_ZXilVhiZgb^cViZYYjZidXdaYY^hXdb[dgi!
VcYcdgZhjaih[gdbi]^hhjW_ZXilZgZ^cXajYZY#Cdh^\chd[
h]^kZg^c\lZgZdWhZgkZY^cVcnd[i]ZgZbV^c^c\hjW_ZXih#
HdbZ^cY^k^YjVaVecdZVhlZgZZmXajYZY [gdb VcVanh^h
WZXVjhZd[dWk^djhgZXdgY^c\aVehZh!WjiXVaXjaVi^dchValVnh
;^\jgZ'
BZVcH:BX]Vc\Zh[gdbgZ[ZgZcXZ^c6]ZVgigViZc2&*07bZVcVgiZg^VaegZhhjgZc2&&0VcY
8VWhdajiZkVajZh[dgh`^cWaddYÅdlc2&)[dgYgn"WdYnVcY^bbZghZY"WdYnXdcY^i^dch!VkZgV\ZYdkZg*h
eZg^dYh0kZgi^XVaYVh]Zh^cY^XViZi]ZWZ\^cc^c\VcYZcYd[VecdZVh
ŶVecdZV^cV^g0ƑVecdZVl^i][VXZ^bbZgh^dc0E1%#%%&
8
6
7
 
http://archive.rubicon-foundation.org
9^k^c\VcY=neZgWVg^XBZY^X^cZKdajbZ(.Cd#)9ZXZbWZg'%%. &.,
^cXajYZViaZVhiildVecdZVheZghjW_ZXieZghZg^Zh!VhVWVh^h
[dgVc^cY^k^YjVabZVc#6aahjW_ZXihlZgZVWaZideZg[dgb
i]Z^gegZYZiZgb^cZYVecdZVYjgVi^dc!ZmXZeidcZl]d]VY
hdbZegdWaZbhl^i]i]ZÄghiVecdZVh#
:;;:8IHD;7D9N>BB:GH>DC
CdY^[[ZgZcXZh^cB6EdgHVD'lZgZcdiZYYjg^c\Vcnd[
i]ZgZhieZg^dYhWZ[dgZi]Z VecdZVh! Wji =GlVhha^\]ian
ZaZkViZY)#+Web0.*8>(#*!%#&0E1%#%%&VcYH`7;
gZYjXZY(#,ba#b^c"&#&%%\"&0.*8>'#,!%#%.0E1%#%%&
^ci]Z^bbZghZY"WdYnXdcY^i^dcIVWaZ&#
9>K>C<G:HEDCH:
I]Z=GVcYB6EYjg^c\VecdZVh]dlZYh^b^aVgeViiZgch
^cVaahZg^Zh#I]ZWgVYnXVgY^VlVhbdgZegdcdjcXZY^ci]Z
9;>6&-VcY>;>6&,hZg^Zhl]ZcXdbeVgZYidi]Z
96.VcY>6.hZg^ZhY^[[ZgZcXZ96·9;>6.#(!
.*8>(#*!%#&)0Y^[[ZgZcXZ>6·>;>6,#.!.*8>)#-!
%#'0;^\jgZ'6#I]ZZc]VcXZY WgVYnXVgY^V Yjg^c\ [VXZ
^bbZgh^dclVhXdch^hiZciVXgdhhi]ZhZg^Zhd[VecdZVh^c
Wdi]i]ZYgn"WdYnVcY^bbZghZY"WdYnXdcY^i^dch#I]ZgZ
lZgZcdY^[[ZgZcXZh^c =G WZilZZci]ZeddaZYYgn"WdYn
VcY^bbZghZY"WdYnhZg^Zh"%#)!.*8>(#'! %#&#
I]ZgZlZgZcdY^[[ZgZcXZh^cB6EWZilZZc96VcY9;>6
"&#+!.*8>'#,!%#&!dg>6VcY>;>6"(#,!.*8>
+#'!%#'#=dlZkZg!i]ZB6E^cXgZVhZYbdgZ^ci]ZeddaZY!
^bbZghZY"WdYnhZg^Zh+#-!.*8>(#&!%#&0;^\jgZ'7#
I]ZH`7;eViiZgchlZgZh^b^aVg^ci]ZYgn"WdYnhZg^Zh!Wji
H`7;lVhgZYjXZYbdgZ^c9;>6XdbeVgZYid96&+#%!
.*8> -#)!%#(# H`7;lVhadlZg^ci]Z^bbZghZY"WdYn
XdcY^i^dchXdbeVgZY idi]ZYgn"WdYnXdcY^i^dch"(.#(!
.*8>'-#'! %#.0E1%#%& VcYcdY^[[ZgZcXZh ^cH`7;
lZgZ[djcYWZilZZc>6VcY>;>6'#,!.*8>'.#+!%#.0
;^\jgZ'8#
6GI:G>6ADMN<:CH6IJG6I>DC
I]ZbdgZegdcdjcXZYY^k^c\gZhedchZ Yjg^c\ [VXZ
^bbZgh^dc;^\jgZ'lVhVhhdX^ViZYl^i] aZhh VgiZg^Va
YZhVijgVi^dc!gZ\VgYaZhhd[WdYn^bbZgh^dchiVijh;^\jgZ
(#I]ZHVD'cVY^g!XdggZhedcY^c\idi]ZZcYd[i]ZVecdZV!
h]dlZY*%aZhhYZhVijgVi^dc^c9;>6XdbeVgZYid96!VcY
^c>;>6XdbeVgZYid>6VWhdajiZY^[[ZgZcXZhlZgZ"%#)!
.*8>%#'!%#%&VcY"%#)!.*8>%#)!%#%gZheZXi^kZan0
;^\jgZ(#
G:HE>G6IDGNE6G6B:I:GH
I]ZbZVc£H9K8[dgi]ZegdcZedh^i^dclVh.))d[
i]ZhiVcY^c\K8E1%#%%&VcY!^ci]Z^bbZghZYedh^i^dc!
^ilVh--+d[i]ZhiVcY^c\K8E1%#%%&0K8^ci]Z
^bbZghZYedh^i^dclVh.),d[i]Vi^ci]ZegdcZedh^i^dc
E1%#%&#I]ZgZlZgZcdY^[[ZgZcXZhWZilZZchZg^Zh^cAK^c!
ZcY"i^YVa[gVXi^dcd[D';:ID'VcYZcY"i^YVa[gVXi^dc d[
8D';:I8D'Vii]ZaVhiWgZVi]WZ[dgZVecdZV#I]ZgZaVi^kZ
^cÅVi^dcd[i]Zajc\hlVh+&'&^ci]ZYgn"WdYnXdcY^i^dc
VcY+)'%^ci]Z^bbZghZY"WdYnXdcY^i^dc ')#(0
.*8>)#.!%#'0CH#6ii]ZZcYd[i]ZVecdZV!i]ZgZlVh
cdY^[[ZgZcXZ^cAKZmeWZilZZc Vaa hZg^Zh! Wji Y^[[ZgZcXZh
lZgZ[djcY^c;:ID'VcY;:I8D'# I]Z ;:ID' lVh]^\]Zg
V[iZg>;>6XdbeVgZYid>6'%#,0.*8>%#)!%#%&0E1
%#%%&!l]^aZi]ZgZlZgZcdY^[[ZgZcXZhWZilZZc9;>6VcY
96!dg^c;:I8D'IVWaZ&#>ci]ZeddaZYYgn"WdYnhZg^Zh!
i]Z;:ID'lVh ]^\]ZgV[iZgVecdZVh'&#(0 .* 8>%#*!
%#%'0E1%#%%&l]^aZi]Z;:I8D'lVhadlZgXdbeVgZYid
i]ZeddaZY^bbZghZY"WdYnhZg^Zh'%#(0.*8> %#&+!
%#%%*0E1%#%%&0IVWaZ&#
8DB;DGIG6I>C<
I]ZhjW_ZXihgViZYi]Z^bbZghZY edh^i^dc^ci]ZiVc`aZhh
Xdb[dgiVWaZi]Vci]ZbZVcH9egdcZedh^i^dc dc i]Z
;^\jgZ(
BZVcH:BX]Vc\Zh[gdbgZ[ZgZcXZ^cVgiZg^Vadmn\ZchVijgVi^dc[dg&)hjW_ZXih[dgi]ZYgn"WdYnVcYi]Z
^bbZghZY"WdYnXdcY^i^dch!VkZgV\ZYdkZg*heZg^dYh0i]ZcVY^gXdggZhedcYhl^i]i]ZZcYd[i]ZVecdZVWji^h
YZaVnZYYjZidX^gXjaVi^dci^bZ0kZgi^XVaYVh]Zh^cY^XViZi]ZWZ\^cc^c\VcYZcYd[VecdZVh0
ŶVecdZV^cV^g0ƑVecdZVl^i][VXZ^bbZgh^dc0E1%#%%&0E1%#%*

http://archive.rubicon-foundation.org
9^k^c\VcY=neZgWVg^XBZY^X^cZKdajbZ(.Cd#)9ZXZbWZg'%%.&.-
WZY+'[dgiVc`VcY-&[dgWZY0E1%#%%&#L^i]dji
i]ZhjW_ZXil]d^ciZggjeiZY iZhih YjZ idXdaYY^hXdb[dgi!
i]Z\gdjeZmegZhhZYcdhjW_ZXi^kZXdaYegdWaZbhi]ZgbVa
Xdc[dgibZVchXdgZ-!gVc\Z*·&%YZhe^iZi]ZX]^aa^c\Z[[ZXi
dci]Zh`^cZk^YZci[gdbi]ZgZYjXZYh`^cWaddYÅdl#
9^hXjhh^dc
;gdbi]^hhijYn!dcZbVnXdcXajYZi]Vi[VXZ ^bbZgh^dc
Yjg^c\VecdZVXVjhZhVbdgZedlZg[jaY^k^c\gZhedchZ!
gZYjX^c\WaddYÅdlVcYD'Xdchjbei^dc[jgi]ZgXdbeVgZY
idVecdZVVadcZ#'!(I]Z gZhjaih ^cY^XViZ i]Vi i]Z Y^k^c\
gZhedchZgZYjXZhdmn\ZcXdchjbei^dc^ci]Z^bbZghZY
Y^kZg^cVh^b^aVgbVccZgidi]Vi^ci]ZYgn!h^bjaViZYY^k^c\
bdYZa!l]^X]]VhcdiegZk^djhanWZZch]dlc#:kZci]dj\]
Wdi]VbW^ZciVcYlViZgiZbeZgVijgZlZgZ'(D8!i]ZY^k^c\
gZhedchZlVhbdgZegdcdjcXZYl]ZcVecdZVlVhXdbW^cZY
l^i][VXZ ^bbZgh^dc!gZ\VgYaZhhd[WdYn^bbZgh^dc#I]^h
h]dlhi]Vii]ZX]^aa^c\Z[[ZXid[i]ZlViZgdci]Z[VX^Vah`^c
lVhhj[ÄX^ZciidZa^X^iVhigdc\ZgY^k^c\gZhedchZYZhe^iZi]Z
higdc\egZ"VecdZ^XkVhdXdchig^Xi^dcYjg^c\WdYn^bbZgh^dc#
I]ZZc]VcXZYY^k^c\gZhedchZYjg^c\[VXZ^bbZgh^dclVh
Xdch^hiZcii]gdj\]djii]ZhZg^Zh!h]dl^c\i]Vi hj[ÄX^Zci
[VX^VagZ"lVgb^c\dXXjggZY^ci]Zild"b^cjiZ ^ciZgkVah
WZilZZcVecdZVh#;dgi]ZY^kZg!i]^h hj\\Zhih i]Vi ^i ^h
^bedgiVciidZmedhZi]Z[VX^VaVgZV^ckdakZY^cig^\\Zg^c\i]Z
Y^k^c\gZhedchZ[dgVX]^Zk^c\bVm^bVaD'XdchZgkVi^dc#I]Z
bV^ccZjgVa^ceji[gdbi]Z[VXZ^hi]gdj\]i]Zde]i]Vab^X
WgVcX]d[i]Zig^\Zb^cVacZgkZ!^#Z#!i]Z[dgZ]ZVYVcYZnZ
gZ\^dc#&.I]Z[VXZbVh`h]djaY!i]ZgZ[dgZ!cdiXdkZgVaad[
i]^hVgZV;^\jgZ)#I]Zha^\]i^cXgZVhZ^c]ZVgigViZdWhZgkZY
_jhiWZ[dgZi]ZVecdZVh]VhWZZcegZk^djhanVhXg^WZYidVc
Vci^X^eVidgngZhedchZ#&+I]Z^c^i^Va^cXgZVhZ^cHVD'Yjg^c\
VecdZV^hgZaViZYidi]ZaVg\Z^che^gVi^dc#
I]ZVgiZg^Va]VZbd\adW^cYZhVijgVi^dclVhaZhhegdcdjcXZY
Yjg^c\[VXZ^bbZgh^dc!^cWdi]Ygn" VcY ^bbZghZY"WdYn
XdcY^i^dch!^cY^XVi^c\i]ViD'Xdchjbei^dclVhgZYjXZYWn
i]Z^cXgZVhZYY^k^c\gZhedchZ#I]^h dmn\Zc XdchZgkVi^dc
ldjaYdXXjgbV^cank^Vi]Z[daadl^c\bZX]Vc^hbh/
7ngZYjXZYeZg[jh^dcd[dg\Vchi]Vi XVc l^i]hiVcY
igVch^Zci]nedm^VWngZan^c\dcVcVZgdW^XeVi]lVnh!
egZhZgk^c\bdhid[i]ZVkV^aVWaZdmn\Zc[dgi]ZjhZd[
i]Z]ZVgiVcYWgV^c0&
7ngZYjXZYbndXVgY^VaD 'YZbVcYi]gdj\]i]ZgZYjXi^dc
^c=G!l]^X][jgi]ZggZYjXZhdmn\ZcjhV\Z0.
I]ZX]^aa^c\d[eZg^e]ZgVai^hhjZhbVnVahd ^c ^ihZa[
gZYjXZadXVaVcYi]ZgZWndkZgVaabZiVWda^hb! Vhadc\
Vhh]^kZg^c\^hcdi^cYjXZY#
L]^aZi]^hhijYngZkZVahVcdmn\Zc"XdchZgk^c\Z[[ZXil]Zc
VecdZV^heZg[dgbZYl^i]i]ZWdYn^bbZghZY!i]jhVYY^c\
WdYnXdda^c\VcYZa^b^cVi^c\i]ZZ[[ZXihd[\gVk^inXdbeVgZY
idi]ZYgnbdYZa!^iYdZhcdihijYni]ZZ[[ZXihd[egZhhjgZ
egZhZciYjg^c\YZZeY^kZh#>i ]Vh WZZc h]dlcWnZVga^Zg
hijY^Zhi]ViXVgY^VXeZg[dgbVcXZYjg^c\VecdZ^XZmedhjgZid
^cXgZVhZYVbW^ZciegZhhjgZVi'%bZigZh¼bYZei]^hh^b^aVg
idi]ViYjg^c\VecdZVVii]Zhjg[VXZ#&,7gVYnXVgY^VlVhVahd
h]dlcidWZh^b^aVgYjg^c\XdcigdaaZYY^kZh^cVY^k^c\iVc`
Vi&%bVcY&+ bYZei]#'% HijY^Zhd[i]ZZ[[ZXihd[ajc\
kdajbZhdci]ZY^k^c\WgVYnXVgY^Vh]dli]Vii]ZgZYjXi^dc^c
ajc\kdajbZYjZid^cXgZVhZYegZhhjgZViYZei]ldjaYa^`Zan
Zc]VcXZi]ZY^k^c\gZhedchZ#'&>cVYY^i^dc!i]ZY^kZg^ci]Z
ÄZaYl^aa^cbdhih^ijVi^dch ZcXdjciZgXdaYZglViZgl]Zc
aZVk^c\i]Zhjg[VXZ!l]^X]^cijgch]djaYZc]VcXZi]ZY^k^c\
gZhedchZ#*!''IV`Zcid\Zi]Zg!i]^hhjeedgihi]ZXdcXajh^dci]Vi
i]ZY^k^c\gZhedchZXdchZgkZhD'^ci]Z^bbZghZYY^kZgid
ViaZVhii]ZhVbZZmiZciVh^ch^bjaViZYY^kZh!Wdi]Yjg^c\
h]VaadlVcYYZZeY^kZh#
I]ZgZYjXi^dc^cH`7;WZ[dgZi]ZVecdZVh^ci]Z^bbZghZY"
WdYnXdcY^i^dc!XVjhZYWnhigdc\kVhdXdchig^Xi^dcWZXVjhZ
d[i]ZX]^aa^c\Z[[ZXid[i]ZlViZg!YdZhcdiVeeZVgid]VkZ
VcZ[[ZXidci]ZbV\c^ijYZd[i]ZdkZgVaaY^k^c\gZhedchZ#
9Zhe^iZi]ZXdchiVciadlh`^c eZg[jh^dc Yjg^c\ WdYn
^bbZgh^dc!i]ZWaddYegZhhjgZ^cXgZVhZYbdgZYjg^c\i]ZhZ
VecdZVh!XdbeVgZYidi]ZYgn"WdYnXdcY^i^dc!l]ZccdgbVa
h`^ceZg[jh^dceZg^dYh egZXZYZY i]ZVecdZVh#I]^h h]dlh
i]Vidi]ZgkVhXjaVgWZYh!^#Z#!^ci]ZVWYdb^cVadg\Vch!bVn
Xdchig^XibdgZ!VcYhj[ÄX^ZcianXdbeZchViZ[dgi]Zb^cdg
VYY^i^dcVah`^ckVhdXdchig^Xi^dcYjg^c\^bbZgh^dc!XVjh^c\
Vh^b^aVgZ[[ZXidcidiVaeZg^e]ZgVagZh^hiVcXZVhYjg^c\i]Z
cdc"^bbZghZYXdcY^i^dc#
I]ZgZhi^c\=G^ci]Z^bbZghZY"WdYnh^ijVi^dc^hha^\]ian
]^\]Zgi]Vc^ci]ZYgn"WdYnh^ijVi^dc!l]^X]bVngZhjai[gdb
^cXgZVhZYbjhXjaVgiZch^dcYjZid XdaY VcY Vc^cXgZVhZY
Z[[dgi[gdbbV^ciV^c^c\WdYnedh^i^dc l]^aZ [adVi^c\#
I]ZaViiZgZmeaVcVi^dchZZbhhjeedgiZYWn i]Z gZhjaih
[gdbi]ZfjZhi^dccV^gZ! l]^X]h]dlZYi]Vi hjW_ZXihlZgZ
aZhhXdb[dgiVWaZ^c i]Z^bbZghZYh^ijVi^dc YjZid[VXidgh
cdiVhhdX^ViZYl^i]X]^aa^c\#I]^h bVn Vahd ZmeaV^c i]Z
Y^[[ZgZcXZhWZilZZckVajZh^c;:ID'VcY;:I8D'[djcYV[iZg
i]ZVecdZV!l]ZgZ^cXgZVhZYbjhXjaVgiZch^dcegdWVWan
;^\jgZ)
6Y^kZgl]dZmedhZhi]Z[VX^VaVgZVig^\\Zg^c\i]Z
dmn\Zc"XdchZgk^c\Y^k^c\gZhedchZaZ[iVcYVY^kZg
l]dXdkZghVaad[i]ZjeeZg[VXZl^i]bVh`VcY]ddY
g^\]i!jca^`ZanidWZcZÄi[gdbi]ZZ[[ZXid[X]^aa^c\
http://archive.rubicon-foundation.org
9^k^c\VcY=neZgWVg^XBZY^X^cZKdajbZ(.Cd#)9ZXZbWZg'%%. &..
XVjhZYVc^cXgZVhZ^cD'jhV\ZVcY8D'egdYjXi^dcYjg^c\
WdYn^bbZgh^dc#I]Z^cXgZVhZYbZiVWda^hbYdZhcdihZZb
idV[[ZXii]ZZmiZcid[WgVYnXVgY^VYjg^c\VecdZV#I]^hV\gZZh
l^i]ZVga^ZgÄcY^c\hd[WgVYnXVgY^VYjg^c\VecdZVh l^i]
bdYZgViZZmZgX^hZVcYhl^bb^c\!gZVX]^c\]ZVgi gViZhd[
ViaZVhiVhadlaZkZahVhYjg^c\^cVXi^kZY^kZh#-!'(
8dcXajh^dch
8daYhi^bjaVi^dcd[i]Z[VXZeaVnh Vc ^bedgiVci gdaZ ^c
i]ZZmiZcid[i]Z»Y^k^c\gZhedchZ¼YZkZadeZYYZhe^iZ
XdchiVciWdYn^bbZgh^dc ^cXddalViZg!VcY i]^haZVYhid
D'XdchZgkVi^dc^ci]ZY^kZg#I]Zdmn\Zc"XdchZgk^c\Z[[ZXi
d[i]ZY^k^c\gZhedchZ^ci]Z^bbZghZYY^kZg^hd[i]ZhVbZ
bV\c^ijYZVhi]VidWhZgkZY^ci]Z Ygn!]dg^odciVa"WdYn
aVWdgVidgnbdYZajhZYidh^bjaViZY^k^c\!l]^X]hj\\Zhih
i]Vii]Zh^bjaViZYY^k^c\bdYZa^hkVa^YVcYXVcWZjhZY[dg
[jgi]ZghijY^Zhd[Y^k^c\"gZhedchZ[jcXi^dch^cY^kZgh#
6X`cdlaZY\ZbZcih
LZi]Vc`VaahjW_ZXih[dgi]Z^geVgi^X^eVi^dcVcYBgE@Vgahhdc
VcYhijYZcih[dgVhh^hiVcXZYjg^c\ZmeZg^bZcih#I]^hhijYn
lVhhjeedgiZYWn\gVcih[gdbi]ZHlZY^h]CVi^dcVa8ZcigZ
[dgGZhZVgX]^cHedgih8>;VcYi]Z8djcin6Yb^c^higVi^kZ
7dVgYd[K~hiZgcdggaVcY!=~gchVcY!HlZYZc#
GZ[ZgZcXZh
:ahcZgG!<ddYZc7#& 9^k^c\VcYVhe]nm^V/V XdbeVgVi^kZ
hijYnd[Vc^bVahVcYbVc#E]nh^dad\^XVaHdX^ZinBdcd\gVe]
)%#8VbWg^Y\Z/8VbWg^Y\ZJc^kZgh^inEgZhh0&.-(#
<ddYZc76#BZX]Vc^hbd[i]Z]jbVcY^k^c\gZhedchZ#' >ciZ\g
E]nh^da7Z]VkHX^#&..)0'./+"&+#
@VlV`Vb^N!CViZahdc7=! 9j7d^h6G#8VgY^dkVhXjaVg(
Z[[ZXihd[[VXZ^bbZgh^dcVcY[VXidghV[[ZXi^c\Y^k^c\gZÅZm
^cbVc#?6eeaE]nh^da#&.+,0'(/.+)",%#
=jgl^io7:!;jgZYn??# I]Z ]jbVcY^kZgZ[aZm/ Vc)
ZmeZg^bZciVa!ided\gVe]^XVaVcYe]nh^dad\^XVa VcVanh^h#
E]nh^da7Z]Vk#&.-+0(+/'-,".)#
HX]V\ViVn:!=dab7# :[[ZXih d[lViZgVcYVbW^Zci V^g*
iZbeZgVijgZdc]jbVcY^k^c\WgVYnXVgY^V#:jg?6eeaE]nh^da#
&..+0,(/&"+#
HX]V\ViVn:!6cYZghhdc?#9^k^c\gZhedchZVcYVecZ^Xi^bZ^c+
]jbVch#JcYZghZV=neZgWVg^XBZY#&..-0'*/&("&.#
6cYZghhdc?!HX]V\ViVn:#6giZg^Vadmn\ZcYZhVijgVi^dcYjg^c\,
VecZV^c]jbVch#JcYZghZV=neZgWVg^XBZY#&..-0'*/'&"*#
6cYZghhdc?E6!A^cgB=!Gcdl:!HX]V\ViVn:@6#9^k^c\-
gZhedchZVcYVgiZg^Vadmn\Zc hVijgVi^dc Yjg^c\ VecZVVcY
ZmZgX^hZ^cWgZVi]"]daYY^kZgh#?6eeaE]nh^da#'%%'0.(/--'"
+#
A^cN8#7gZVi]"]daYY^k^c\ ^ciZggZhig^VaVc^bVah#. :mZgX^hZ
HedgiHX^GZk#&.-'0&%/',%"(%,#
6cYZghhdc?!A^cgB!;gZYhiZY6!HX]V\ViVn:#8VgY^dkVhXjaVg&%
VcYgZhe^gVidgngZhedchZhid VecZVh l^i] VcYl^i]dji
[VXZ^bbZgh^dc^cZmZgX^h^c\ ]jbVch# ?6eeaE]nh^da#
'%%)0.+/&%%*"&%#
6cYZghhdc?!7^VhdaZiid"I_Zaahigb<! HX]V\ViVn :#&&
EjabdcVgn\VhZmX]Vc\Z^h gZYjXZY Wni]ZXVgY^dkVhXjaVg
Y^k^c\gZhedchZ^cgZhi^c\]jbVch#GZhe^gE]nh^daCZjgdW^da#
'%%-0&+%/('%")#
8VbeWZaaA7!<ddYZc76! =dgdl^io?9#8VgY^dkVhXjaVg&'
gZhedchZhid eVgi^VaVcY idiVa^bbZgh^dc ^cbVc# ?E]nh^da#
&.+.0'%'/'(."*%#
<ddYZc76!AZ]bVc G<! Enb ?#GdaZd[i]Z [VXZ ^ci]Z&(
XVgY^dkVhXjaVggZhedchZhididiVa^bbZgh^dc#6jhi?:me7^da
BZYHX^#&.,%0)-/+-,".%#
HiZgWV?6! AjcY\gZc8:<#9^k^c\WgVYnXVgY^VVcYWgZVi]"&)
]daY^c\i^bZ^c bVc#JcYZghZV7^dbZY GZh#&.-*0&'/&(."
*%#
EVjaZkE:#GZhe^gVidgnVcYXVgVY^dkVhXjaVgZ[[ZXihd[WgZVi]"&*
]daY^c\#6XiVE]nh^daHXVcY#&.+.0Hjeea(')/&&+ee#
6cYZghhdc?!HX]V\ViVn:!<^hac6!=dab7#8VgY^dkVhXjaVg&+
gZhedchZhidXdaY"lViZg^bbZgh^dch d[ i]Z [dgZVgbVcY
[VXZ!VcYi]Z^g gZaVi^dch]^e idVecdZV#:jg ?6eeaE]nh^da#
'%%%0-(/*++",'#
;Zgg^\cdB!=^X`Zn99!A^cgB=!AjcY\gZc8:<#H^bjaViZY&,
WgZVi]"]daYY^k^c\id '% bZiZgh/ XVgY^VXeZg[dgbVcXZ^c
]jbVch#?6eeaE]nh^da#&.-,0+'/'&+%",#
=ZVi]?G!>gl^c8?#6c^cXgZVhZ^cWgZVi]"]daYi^bZVeeZVg^c\&-
V[iZgWgZVi]"]daY^c\#GZhe^gE]nh^da#&.+-0)/,(",#
HX]j^iZbV@! =dab7#I]ZgdaZd[Y^[[ZgZci[VX^VaVgZVh ^c&.
Za^X^i^c\]jbVcY^k^c\WgVYnXVgY^V# 6XiV E]nh^daHXVcY#
&.--0&('/&&."'%#
<ZcchZgB!HX]V\ViVn:!6cYZghhdc?!AV\ZgXgVcio7!7Zcdc^'%
9!ygc]V\Zc=#8VgY^dgZhe^gVidgnZ[[ZXihd[VecdZ^XY^kZhVcY
[gZZVhXZcih^cildXaVhhZhd[Y^kZgh#>c/H]jeV`6G!A^cXdac
G!<gdhhbVcN!ZY^idgh#EgdXZZY^c\h'*i]6ccjVaHX^Zci^ÄX
BZZi^c\d[i]Z:jgdeZVc JcYZglViZgVcY7VgdbZY^XVa
HdX^Zin!=V^[VVcY:^aVi!>hgVZa0&...#e#''-"(&#
6cYZghhdc?!HX]V\ViVn:# :[[ZXih d[ajc\kdajbZVcY'&
^ckdajciVgnWgZVi]^c\ bdkZbZcihdci]Z]jbVc Y^k^c\
gZhedchZ#:jg?6eeaE]nh^da#&..-0,,/&."')#
;Zgg^\cdB!<gVhh^7! ;ZggZii^ <! 8dhiVB!BVgXdc^8!''
8ZggZiZaa^EZiVa#:aZXigdXVgY^d\gVbYjg^c\YZZeWgZVi]"]daY
Y^kZhWnZa^iZY^kZgh#JcYZghZV7^dbZYGZh#&..&0&-/-&".&#
7jiaZgE?!LdV`Zh6?#=ZVgigViZ^c]jbVchYjg^c\jcYZglViZg'(
hl^bb^c\l^i]VcYl^i]dji WgZVi]"]daY# GZhe^g E]nh^da#
&.-,0+./(-,"..#
HjWb^iiZY/&*?VcjVgn'%%.
6XXZeiZY/%)DXidWZg'%%.
GdWZgiYZ7gj^_c!BHX!lVhVedhi\gVYjViZhijYZciVii]Z
i^bZd[i]ZhijYn!VcY^hXjggZcianjcYZgiV`^c\YdXidgVa
gZhZVgX]^chigZhhe]nh^dad\nVi Ij[ihJc^kZgh^in! 7dhidc!
JH6#
BViiG^X]VgYhdc!E]9!^hVgZhZVgX]ZgVcY
:g^`VHX]V\ViVn! E]9!^hEgd[ZhhdgVii]Z :ck^gdcbZciVa
E]nh^dad\n<gdjeVi i]Z9ZeVgibZcid[ :c\^cZZg^c\VcY
HjhiV^cVWaZ9ZkZadebZciVcYVii]ZHlZY^h]L^ciZghedgih
GZhZVgX]8ZcigZ!B^YHlZYZcJc^kZgh^in!yhiZghjcY#
6YYgZhh[dgXdggZhedcYZcXZ/
:g^`VHX]V\ViVn
:ck^gdcbZciVaE]nh^dad\n<gdje
9ZeVgibZcid[:c\^cZZg^c\VcYHjhiV^cVWaZ9ZkZadebZci
B^YHlZYZcJc^kZgh^in
6`VYZb^\ViVc&!-(&'*yhiZghjcY!HlZYZc
E]dcZ/ )+"%+("&+**&'
;Vm/ )+%+("&+*,%%
:"bV^a/1Zg^`V#hX]V\ViVn5b^jc#hZ3
http://archive.rubicon-foundation.org
... Results from earlier studies observing the differences in cardiovascular mechanisms during prolonged apnoeas in dry vs. immersive environments have found that end-systolic volume is greater in immersion apnoea than dry apnoea (Marabotti et al., 2013), while no differences in HR changes were found. Decreases in HR and increases in arterial pressure have also been found to be no different during apnoeas in dry vs. immersive environments, if apnoea is performed with full facial immersion in water (de Bruijn et al., 2009). Our findings can confirm these findings, as facial immersion alone appears to be an adequate HDR trigger; however, the environmental condition can affect the magnitude of the HDR response regardless of the environmental condition (de Bruijn et al., 2009). ...
... Decreases in HR and increases in arterial pressure have also been found to be no different during apnoeas in dry vs. immersive environments, if apnoea is performed with full facial immersion in water (de Bruijn et al., 2009). Our findings can confirm these findings, as facial immersion alone appears to be an adequate HDR trigger; however, the environmental condition can affect the magnitude of the HDR response regardless of the environmental condition (de Bruijn et al., 2009). ...
Article
Full-text available
Introduction: The human dive reflex (HDR), an O2 conserving reflex, is characterised by an interplay of central parasympathetic and peripheral sympathetic reactions, which are presumed to operate independently of each other. The HDR is fully activated during apnoea with facial immersion in water and complete immersion in water is thought to increase the magnitude of HDR during consecutive apnoeas. A comparison of HDR activity between consecutive apnoeas in full-body immersion with consecutive apnoeas in dry conditions has not been fully explored. Also, the interplay between parasympathetic and sympathetic reactions involved in the HDR has not been thoroughly analysed. Methods: 11 human volunteers performed 3 consecutive 60 s apnoeas with facial immersion in dry conditions (FIDC) and 3 consecutive apnoeas with facial immersion in full immersion (FIFI). Heart rate (HR), R-R interval (RRI), finger pulse amplitude (FPA), splenic width (SW) and SpO2 were all measured before, during and after apnoeas. A one-way ANOVA using Dunn’s post hoc test was performed to assess HDR activity, and a Pearson’s correlation test was performed to assess HDR synchronisation between physiological parameters during both conditions. Results: Although HDR activity was not significantly different between both conditions, HR and RRI showed progressively greater changes during FIFI compared with FIDC, while SW and FPA changes were relatively equivalent. During FIDC, significant correlations were found between SW & SpO2 and FPA & SpO2. During FIFI, significant correlations were found between RRI & FPA, SW & FPA, HR & SpO2 and FPA & SpO2. Discussion: While there was no significant difference found between HDR activity during FIDC and FIFI, consecutive apnoeas during FIFI triggered a greater magnitude of cardiac activity. Furthermore, significant correlations between RRI and SW with FPA indicate a crosstalk between parasympathetic tone with splenic contraction and increased peripheral sympathetic outflow during FIFI compared to FIDC. In conclusion, HDR activity during consecutive apnoeas does not differ between FIDC and FIFI. There appears to be however a greater level of synchronicity during apnoeas in FIFI compared to FIDC and that this is most likely due to the physiological effects of immersion, which could induce neural recruitment and increased cross talk of HDR pathways.
... Observed in diving animals, archetypal DR consists of the coordinated activation of at least three reflexes: simultaneous activation of parasympathetic and sympathetic systems and respiratory adjustments (2,3). Activation of these reflexes leads, respectively, to bradycardia (4-10), peripheral vasoconstriction limiting blood supply to muscles and "non-critical" organs (2,(11)(12)(13)(14)(15), increase in arterial pressure (2,(16)(17)(18), and apnea (12,18,19). Diving response is initiated by the excitation of the ophthalmic division of the trigeminal nerve (2), which innervates nasal mucosa, cornea, forehead, and cerebral dura mater (20,21). ...
... Integral effect of DR is overall decreased oxygen consumption and preservation of vital functioning of heart and brain during apneic period (17,(36)(37)(38). DR, an evolutionary ancient mechanism of survival of low-oxygen/anoxic conditions (39)(40)(41), presents in all animals (1) and exerts powerful protection against anoxic conditions (42). ...
Article
Full-text available
Diving response (DR) is a powerful integrative response targeted toward survival of the hypoxic/anoxic conditions. Being present in all animals and humans, it allows to survive adverse conditions like diving. Earlier, we discovered that forehead stimulation affords neuroprotective effect, decreasing infarction volume triggered by permanent occlusion of the middle cerebral artery in rats. We hypothesized that cold stimulation of the forehead induces DR in rats, which, in turn, exerts neuroprotection. We compared autonomic [AP, heart rate (HR), cerebral blood flow (CBF)] and EEG responses to the known DR-triggering stimulus, ammonia stimulation of the nasal mucosa, cold stimulation of the forehead, and cold stimulation of the glabrous skin of the tail base in anesthetized rats. Responses in AP, HR, CBF, and EEG to cold stimulation of the forehead and ammonia vapors instillation into the nasal cavity were comparable and differed significantly from responses to the cold stimulation of the tail base. Excitotoxic lesion of the subthalamic vasodilator area (SVA), which is known to participate in CBF regulation and to afford neuroprotection upon excitation, failed to affect autonomic components of the DR evoked by forehead cold stimulation or nasal mucosa ammonia stimulation. We conclude that cold stimulation of the forehead triggers physiological response comparable to the response evoked by ammonia vapor instillation into nasal cavity, which is considered as stimulus triggering protective DR. These observations may explain the neuroprotective effect of the forehead stimulation. Data demonstrate that SVA does not directly participate in the autonomic adjustments accompanying DR; however, it is involved in diving-evoked modulation of EEG. We suggest that forehead stimulation can be employed as a stimulus capable of triggering oxygen-conserving DR and can be used for neuroprotective therapy.
... It has been suggested that this co-activation of the sympathetic and parasympathetic systems may lead to increased cardiac efficiency [19]. The conservation of oxygen is a result of lower myocardial oxygen consumption during bradycardia, reduced blood flow to peripheral and visceral organs, and lower oxygen depletion in the lungs [5,[20][21][22]. The combination of decreasing cerebrovascular resistance, increasing perfusion pressure, and reducing peripheral oxygen consumption seems to be an ideal way to preserve the cerebral penumbra. ...
Article
Full-text available
Background: The aim of this study was to analyze cold stimulation-­induced changes in cerebral and cardiac hemodynamics. Methods: Upon ingestion of an ice cube, the changes in resistance index, mean flow velocity and flow index of the middle cerebral arteries (MCA) were assessed using transcranial Doppler sonography. Extracranial duplex sonography was used to measure the mean flow velocity and resistance index of the right internal carotid artery (ICA). The change in mean arterial pressure, heart rate, root mean square of successive differences (RMSSD) and end-­tidal carbon dioxide pressure were analyzed additionally. These changes were compared to sham stimulation. Results: Compared with sham stimulation, cooling of the oral cavity resulted in significant changes in cerebral and cardiac hemodynamics. The cold stimulation decreased the resist- ance index in the MCA (−4.5% ± 5.4%, p < 0.0001) and right ICA (−6.3% ± 15.6%, p = 0.001). This was accompanied by an increase in mean flow velocity (4.1% ± 8.0%, p < 0.0001) and flow index (10.1% ± 43.6%, p = 0.008) in the MCA. The cardiac effects caused an increase in mean arterial pressure (1.8% ± 11.2%, p = 0.017) and RMSSD (55% ± 112%, p = 0.048), while simultaneously decreasing the heart rate (−4.3% ± 9.6%, p = 0.0001). Conclusion: Cooling of the oral cavity resulted in substantial changes in cerebral and cardiac hemodynamics resulting in a blood flow diversion to the brain.
... Since the laboratory is more suitable for advanced physiological measurements than the sea, a vast majority of studies focused on investigating the physiological responses to simulated diving. Studies have often been done by facial immersion and apnea (Lin 1982;Gooden 1994;Foster and Sheel 2005;Schagatay 2009), a setting known to evoke similar protective responses as in an immersed diver at the surface (deBruijn et al. 2009). Studies on breath-hold divers in a pressure chamber have been used to better mimic diving situation (Ferrigno et al. 1997), and yet others have recorded data before and after dives on the surface (Linér and Andersson 2008;Fernandez et al. 2019;Barak et al. 2020;Patrician et al. 2021). ...
Conference Paper
Full-text available
Physiological field research on breath-hold divers (freedivers) is challenging as divers are exposed to hy- perbaric environments hostile to classical physiological measurement methods. Two main challenges are; I) The need of developing methods allowing measurements of physiological variables underwater at depth, II) To accompany the studied freediver in the water. The rapid vertical descent and ascent makes it impossible for researchers to use SCUBA to follow the participants to depth. We present new approaches in scientific diving to meet these demands. Our meth- ods development of underwater technology has included water- and pressure-proof dataloggers to record and store data from a 12 lead ECG (250Hz) and photoplethysmograms from two SpO2 probes using red- and infrared signals (30Hz), combined with ambient pressure and temperature loggers. We previously used SCUBA to enable real-time blood pressure and ECG measurements on freedivers, by waiting for them at the bottom of their pre-determined depth. A breath-hold diving approach for the researcher was found to be superior due to enhanced flexibility in contrast to a heavy, static SCUBA setup. A method was developed in order to perform such scientific freediving safely, the basis being diving in e.g., the professional Japanese Ama divers. Combining the use of novel wearable water- and pressure- proof physiological measurement methods with “scientific freediving”, seems to provide optimal work flexibility for both our study participants and the researcher, and may be the preferred approach for our future research.
... Bradycardia decreases oxygen demand of the heart, and peripheral vasoconstriction limits the blood supply to peripheral non-vital organs while maintaining blood flow to important organs such as brain and heart. [22,[53][54][55] All these effects help reduce oxygen consumption during apnoea (hypoxic state) and thus have a direct oxygen-conserving effect. Several reports describe survival and complete recovery in humans following periods of prolonged (over an hour) submersion in water. ...
Article
Full-text available
Trigeminocardiac reflex (TCR) is a well-established neurogenic reflex although its exact mechanism and clinical significance remain unclear. This reflex may be incited by stimulation of the trigeminal nerve anywhere along its course starting from the peripheral distribution to the central nucleus. It usually manifests as bradycardia, asystole, hypotension, apnoea and gastric hypermotility; though other clinical manifestation such as tachycardia and hypertension may also occur. Diving reflex (DR) shares many similarities with TCR in both clinical manifestation and mechanism of action and is often considered as a modified or subtype of TCR. DR is an important physiological adaptation to withstand hypoxia during apnoea in many animal species including humans and thus belongs to a group of oxygen-conserving reflexes. Although TCR is a physiological reflex having protective function, an exaggerated response may have fatal consequences. Surgeries or stimulation involving head, neck and face region (area supplied by trigeminal nerve) are particularly prone to provoke this reflex. Vigilant and continuous monitoring for early identification of warning signs and communication with surgeon to interrupt the stimulus immediately is enough to cease the reflex in most of the cases. However, failure to identify and treat in time may have deleterious consequences and thus TCR has gained much attention and awareness in recent years. Over the last two decades, our knowledge on TCR has expanded but we still remain far from complete elucidation of pathophysiology, mechanism and clinical significance of this unique ‘brain and heart connection’ called TCR.
... In humans, most of previous and current studies dealing with the oxygen-conserving potential of the human diving response have relied on a comparison of cardiovascular adjustments between dry BH and BH with face immersion/or whole body immersion performed at varying water temperature (Andersson, Biasoletto-Tjellström, & Schagatay, 2008;Andersson & Evaggelidis, 2009;Andersson, Linér, Fredsted, & Schagatay, 2004;Andersson, Linér, Rünow, & Schagatay, 2002;Andersson & Schagatay, 1998;de Bruijn, Richardson, & Schagatay, 2009;Furedy, Morrison, Heslegrave, & Arabian, 1983;Marabotti et al., 2013;Schuitema & Holm, 1988;Sterba & Lundgren, 1988). Surprisingly, only a few have investigated the promising effects of BH training on cardiovascular adjustments to enhance oxygen conservation. ...
... In humans, most of previous and current studies dealing with the oxygen-conserving potential of the human diving response have relied on a comparison of cardiovascular adjustments between dry BH and BH with face immersion/or whole body immersion performed at varying water temperature (Andersson, Biasoletto-Tjellström, & Schagatay, 2008;Andersson & Evaggelidis, 2009;Andersson, Linér, Fredsted, & Schagatay, 2004;Andersson, Linér, Rünow, & Schagatay, 2002;Andersson & Schagatay, 1998;de Bruijn, Richardson, & Schagatay, 2009;Furedy, Morrison, Heslegrave, & Arabian, 1983;Marabotti et al., 2013;Schuitema & Holm, 1988;Sterba & Lundgren, 1988). Surprisingly, only a few have investigated the promising effects of BH training on cardiovascular adjustments to enhance oxygen conservation. ...
... In humans, most of previous and current studies dealing with the oxygen-conserving potential of the human diving response have relied on a comparison of cardiovascular adjustments between dry BH and BH with face immersion/or whole body immersion performed at varying water temperature (Andersson, Biasoletto-Tjellström, & Schagatay, 2008;Andersson & Evaggelidis, 2009;Andersson, Linér, Fredsted, & Schagatay, 2004;Andersson, Linér, Rünow, & Schagatay, 2002;Andersson & Schagatay, 1998;de Bruijn, Richardson, & Schagatay, 2009;Furedy, Morrison, Heslegrave, & Arabian, 1983;Marabotti et al., 2013;Schuitema & Holm, 1988;Sterba & Lundgren, 1988). Surprisingly, only a few have investigated the promising effects of BH training on cardiovascular adjustments to enhance oxygen conservation. ...
... In humans, most of previous and current studies dealing with the oxygen-conserving potential of the human diving response have relied on a comparison of cardiovascular adjustments between dry BH and BH with face immersion/or whole body immersion performed at varying water temperature (Andersson, Biasoletto-Tjellström, & Schagatay, 2008;Andersson & Evaggelidis, 2009;Andersson, Linér, Fredsted, & Schagatay, 2004;Andersson, Linér, Rünow, & Schagatay, 2002;Andersson & Schagatay, 1998;de Bruijn, Richardson, & Schagatay, 2009;Furedy, Morrison, Heslegrave, & Arabian, 1983;Marabotti et al., 2013;Schuitema & Holm, 1988;Sterba & Lundgren, 1988). Surprisingly, only a few have investigated the promising effects of BH training on cardiovascular adjustments to enhance oxygen conservation. ...
Article
We investigated the oxygen-conserving potential of the human diving response by comparing trained breath-hold divers (BHDs) to non-divers (NDs) during simulated dynamic breath-holding (BH). Changes in haemodynamics [heart rate (HR), stroke volume (SV), cardiac output (CO)] and peripheral muscle oxygenation [oxyhaemoglobin ([HbO2]), deoxyhaemoglobin ([HHb]), total haemoglobin ([tHb]), tissue saturation index (TSI)] and peripheral oxygen saturation (SpO2) were continuously recorded during simulated dynamic BH. BHDs showed a breaking point in HR kinetics at mid-BH immediately preceding a more pronounced drop in HR (-0.86 bpm.%(-1)) while HR kinetics in NDs steadily decreased throughout BH (-0.47 bpm.%(-1)). By contrast, SV remained unchanged during BH in both groups (all P > 0.05). Near-infrared spectroscopy (NIRS) results (mean ± SD) expressed as percentage changes from the initial values showed a lower [HHb] increase for BHDs than for NDs at the cessation of BH (+24.0 ± 10.1 vs. +39.2 ± 9.6%, respectively; P < 0.05). As a result, BHDs showed a [tHb] drop that NDs did not at the end of BH (-7.3 ± 3.2 vs. -3.0 ± 4.7%, respectively; P < 0.05). The most striking finding of the present study was that BHDs presented an increase in oxygen-conserving efficiency due to substantial shifts in both cardiac and peripheral haemodynamics during simulated BH. In addition, the kinetic-based approach we used provides further credence to the concept of an "oxygen-conserving breaking point" in the human diving response.
Article
Full-text available
The trigeminocardiac reflex (TCR) is a well-recognized brainstem reflex that represents a unique interaction between the brain and the heart through the Vth and Xth cranial nerves and brainstem nuclei. The TCR has mainly been reported as an intraoperative phenomenon causing cardiovascular changes during skull-base surgeries. However, it is now appreciated that the TCR is implicated during non-neurosurgical procedures and in nonsurgical conditions, and its complex reflex pathways have been explored as potential therapeutic options in various neurological and cardiovascular diseases. This narrative review presents an in-depth overview of hypothetical and experimental models of the TCR phenomenon in relation to the Vth and Xth cranial nerves. In addition, primitive interactions between these 2 cranial nerves and their significance are highlighted. Finally, therapeutic models of the complex interactions of the TCR and areas for further research will be considered.
Article
Full-text available
The effect of the diving response on alveolar gas exchange was investigated in 15 subjects. During steady-state exercise (80 W) on a cycle ergometer, the subjects performed 40-s apneas in air and 40-s apneas with face immersion in cold (10 degrees C) water. Heart rate decreased and blood pressure increased during apneas, and the responses were augmented by face immersion. Oxygen uptake from the lungs decreased during apnea in air (-22% compared with eupneic control) and was further reduced during apnea with face immersion (-25% compared with eupneic control). The plasma lactate concentration increased from control (11%) after apnea in air and even more after apnea with face immersion (20%), suggesting an increased anaerobic metabolism during apneas. The lung oxygen store was depleted more slowly during apnea with face immersion because of the augmented diving response, probably including a decrease in cardiac output. Venous oxygen stores were probably reduced by the cardiovascular responses. The turnover times of these gas stores would have been prolonged, reducing their effect on the oxygen uptake in the lungs. Thus the human diving response has an oxygen-conserving effect.
Article
A portable ECG recorder was used during breath-hold dives at sea by 3 elite divers to 65 and 45 m. ECG was also recorded during nonimmersed maximal breath holds in the divers and 8 control subjects. Heart rate in the dives decreased rapidly to 20-24 beats.min(-1). During the surface experiments in the divers, bradycardia was much slower in onset, reaching 28-36 beats.min(-1) at the end of the breath holds. The divers showed a more consistent bradycardial response than the controls. The difference in temporal pattern of bradycardia, in the dives and in the breath holds by the divers, may have been due to face immersion in cold water, chest compression, and/or redistribution of blood into the chest with concomitant stimulation of cardiac and other mechanoreceptors. Arrhythmias, mostly supraventricular and ventricular premature complexes, were observed coincidently with the lowest heart rates, presumably reflecting a high vagal tone. In addition, cardiac distention at depth might have made the heart more prone to arrhythmias, while in the surface breath holds hypoxia might have accounted for a similar effect.
Article
Cardiac performance was assessed in six subjects breath-hold diving to 20 m in a hyperbaric chamber, while nonsubmersed or submersed in a thermoneutral environment. Cardiac index and systolic time intervals were obtained with impedance cardiography and intrathoracic pressure with an esophageal balloon. Breath holding at large lung volume (80% vital capacity) decreased cardiac index, probably by increasing intrathoracic pressure and thereby impeding venous return. During diving, cardiac index increased (compared with breath holding at the surface) by 35.1% in the nonsubmersed and by 29.5% in the submersed condition. This increase was attributed to a fall in intrathoracic pressure. Combination of the opposite effects of breath holding and diving to 20 m left cardiac performance unchanged during the dives (relative to the surface control). A larger intrathoracic blood redistribution probably explains a smaller reduction in intrathoracic pressure observed during submersed compared with nonsubmersed diving. Submersed breath-hold diving may entail a smaller risk of thoracic squeeze (lesser intrathoracic pressure drop) but a greater risk of overloading the central circulation (larger intrathoracic blood pooling) than simulated nonsubmersed diving.
Article
Heart rate was monitored, by way of radiotelemetry, from 6 male subjects of mean age (+/- SE) 24 +/- 1 years and of mean mass 73.5 +/- 2.5 kg. Measurements were made in a 25 m pool at a water temperature of 28 degrees C. Resting heart rate was 67 +/- 3.7 beats X min-1 and when the subjects submerged themselves completely in the pool, but remained inactive, there was a prompt, gradual reduction in heart rate which reached 48 +/- 2.6 beats X min-1 within 30 sec and 40 +/- 2.6 beats X min-1 within 59 +/- 5.6 sec (maximum duration). When they propelled themselves under water for 33 sec by kicking their legs and breathed through a snorkel tube, heart rate increased progressively to a value of 118 +/- 4.1 beats X min-1 at 28 sec. However, when they performed the same manoeuvre while holding their breath, there was an initial increase in heart rate to 106 +/- 5.7 beats X min-1 within the first 10 sec. This was followed by a decline in heart rate which was more rapid than that recorded during inactive submersion and which eventually reached 48 +/- 4.4 beats X min-1 at mean underwater duration of 33 +/- 1.8 sec. It is concluded that during the first 10-15 sec of underwater breath-hold swimming in humans, the cardiovascular response (as indicated by heart rate) is similar to that seen during a similar level of exercise while breathing air. From then on there is a progressively more intense bradycardia which is probably indicative of an oxygen conserving response consisting of reduced perfusion of most of the body except the heart, CNS and active locomotory muscles. The degree and rate of onset of this proposed oxygen conserving response are influenced by the intensity of the exercise performed while under water and whether or not the period of underwater breath-hold swimming is preceded by exercise.
Article
This study examined the eliciting conditions, response topography and autonomic nervous system (ANS) control of the dive reflex as evoked in humans. Twenty-four subjects received eight trials in each of the three treatment conditions: breath holding without face immersion (BH); face immersion without breath holding (FI); and the "full dive" FIBH condition. It was the combination of both FI and BH in 23 +/- 0.5 degrees C water that was necessary to elicit the dive reflex. A precise topographical analysis differentiated the FIBH condition from the FI and BH control conditions in terms of the emergence of a secondary component initiated approximately 12 seconds after trial onset. During this secondary component, augmentation of bradycardic (mean = 16.3 bpm) and digital vasoconstrictive (mean = -24.9%) responses were maintained throughout the duration of the 40-second dive. A joint consideration of the heart rate and the T-wave amplitude measures as indices of the action of both branches of the ANS suggested that the dive reflex involves concurrent sympathetic and parasympathetic activation. A potential conditioning application of the dive reflex for countering paroxysmal supraventricular tachycardia was discussed.
Article
The hypothesis that the diving response, recorded as diving bradycardia during submersed breath holding in man, would enhance his breath-holding time was tested. Five certified scuba divers served as subjects. They performed breath holds of maximal duration while nonimmersed and during submersion in cool (32 degrees C), cold (20 degrees C), and thermoneutral (35 degrees C) water. The mean breath-holding time and heart rate during the nonimmersed (control) condition were, respectively, 111.2 +/- 14.1 (SE) s and 64.1 +/- 4.7 (SE) beats/min, the relatively long breath-holding times being due primarily to the so-called short-term training effect. Compared to the control values the breath-holding time in 20 degrees C water was 54.9% shorter and heart rate 25.9% lower, in 32 degrees C water the breath-holding time was not different and heart rate was 28.1% lower, and in 35 degrees C water the breath-holding time was longer by 25.6% while there was no difference in heart rate. In all conditions the breath-hold breaking point alveolar PCO2 was the same at about 52 mmHg. The shortening of the breath holds in cold water was ascribed to a 256% increase (over nonimmersed control) in metabolic rate as well as a respiratory drive due to stimulation of skin cold receptors. As for the prolongation of breath holds in thermoneutral water, it was hypothesized that immersion caused a delay in the build-up of chemical stimuli at the chemoreceptors.
Article
Eleven of nineteen young adults development bradycardia and reduced forearm blood flow within 30 seconds of breath-holding with total body immersion and were classified as strong responders. Analysis of data from these strong responders showed that, when the face was lifted from the water after 30 seconds’ total immersion, the development of the diving response ceased, and both heart rate and blood flow returned towards resting levels even though the breath was still held. Conversely, total immersion after 30 seconds of breath- holding with the face in air produced bradycardia of rapid onset and decreased blood flow. Wearing a face mask and swimming cap prevented the development of the usual diving response.
Article
It has been shown that over a series of breath-holds, breath-hold times become progressively longer. This phenomenon still occurs when the amount of air inhaled for each breath-hold is kept constant; it is not abolished when atelactic areas in the lungs are opened up by deep breathing before the series of breath-holds. Pre-breath-hold alveolar Po2 and Pco2 show some evidence for progressive hyperventilation as a cause of breath-hold increase, but it is suggested that subjects may also become habituated to the stresses of breath-holding.
Article
1. Short‐term cardiovascular effects of partial and total immersion of eighteen human subjects in the horizontal plane have been examined. Brachial arterial pressure, heart rate, forearm blood flow and respiratory movements were monitored simultaneously throughout the experiments. Forearm vascular resistance was calculated from the mean blood pressure and mean flow. 2. Total immersion, including the face, with breath‐holding resulted in a 61 ± 43% increase in forearm vascular resistance with an associated 29 ± 15% reduction in forearm blood flow. The concurrent bradycardia was significantly different from the heart rate changes during breath‐holding with the torso only immersed, or during total immersion with snorkel‐breathing. Neither breath‐holding in air or with only the torso immersed, nor total immersion with snorkel‐breathing produced such a diving response. 3. Breath‐holding, after several minutes of total immersion and snorkel‐breathing, produced an attenuated diving response. It therefore appears that a full diving response can be obtained only when the apnoea commences at the moment of face immersion. 4. The present investigation supports the concept that in man face immersion is an essential predisposing factor for the diving response, and cortical inhibition of the respiratory centre is important for its initiation and maintenance.