ArticlePDF Available

The physiological impact of wearing an N95 mask during hemodialysis as a precaution against SARS in patients with end-stage renal disease

Authors:

Abstract

Most patients with end-stage renal disease (ERSD) visiting our hospital for hemodialysis treatment during the SARS outbreak wore an N95 mask. Data on the physiological stress imposed by the wearing of N95 masks remains limited. This study investigated the physiological impact of wearing an N95 mask during hemodialysis (HD) on patients with ESRD. ESRD patients who received regular HD at National Taiwan University Hospital between April to June 2003 were enrolled. Each patient wore a new N95 mask (3M Model 8210) during HD (4 hours). Vital signs, clinical symptoms and arterial blood gas measured before and at the end of HD were compared. Thirty nine patients (23 men; mean age, 57.2 years) were recruited for participation in the study. Seventy percent of the patients showed a reduction in partial pressure of oxygen (PaO2), and 19% developed various degrees of hypoxemia. Wearing an N95 mask significantly reduced the PaO2 level (101.7 +/- 12.6 to 92.7 +/- 15.8 mm Hg, p = 0.006), increased the respiratory rate (16.8 +/- 2.8 to 18.8 +/- 2.7/min, p < 0.001), and increased the occurrence of chest discomfort (3 to 11 patients, p = 0.014) and respiratory distress (1 to 17 patients, p < 0.001). Baseline PaO2 level was the only significant predictor of the magnitude of PaO2 reduction (p < 0.001). Wearing an N95 mask for 4 hours during HD significantly reduced PaO2 and increased respiratory adverse effects in ESRD patients.
T.W. Kao, K.C. Huang, Y.L. Huang, et al
624 J Formos Med Assoc 2004 Vol 103 No 8
THE PHYSIOLOGICAL IMPACT OF WEARING AN N95 MASK
DURING HEMODIALYSIS AS A PRECAUTION AGAINST SARS
IN PATIENTS WITH END-STAGE RENAL DISEASE
Tze-Wah Kao,1 Kuo-Chiang Huang,1 Yu-Ling Huang,2 Tun-Jun Tsai,1 Bor-Shen Hsieh,1 and Ming-Shiou Wu1
1Department of Internal Medicine, National Taiwan University Hospital, Taipei; 2Department of Psychiatry, Shin Kong Wu
Ho-Su Memorial Hospital, Taipei, Taiwan.
Received: 8 January 2004 Revised: 11 February 2004 Accepted: 9 March 2004
Reprint requests and correspondence: Dr. Ming-Shiou Wu, Department of Internal Medicine, National Taiwan University
Hospital, No. 7, Chung-Shan South Road, Taipei, Taiwan.
Background and Purpose: Most patients with end-stage renal disease (ERSD) visiting our hospital for hemodialysis
treatment during the SARS outbreak wore an N95 mask. Data on the physiological stress imposed by the wearing of
N95 masks remains limited. This study investigated the physiological impact of wearing an N95 mask during
hemodialysis (HD) on patients with ESRD.
Methods: ESRD patients who received regular HD at National Taiwan University Hospital between April to June 2003
were enrolled. Each patient wore a new N95 mask (3M Model 8210) during HD (4 hours). Vital signs, clinical
symptoms and arterial blood gas measured before and at the end of HD were compared.
Results: Thirty nine patients (23 men; mean age, 57.2 years) were recruited for participation in the study. Seventy
percent of the patients showed a reduction in partial pressure of oxygen (PaO2), and 19% developed various
degrees of hypoxemia. Wearing an N95 mask significantly reduced the PaO2 level (101.7 ± 12.6 to 92.7 ± 15.8 mm Hg,
p = 0.006), increased the respiratory rate (16.8 ± 2.8 to 18.8 ± 2.7/min, p < 0.001), and increased the occurrence of
chest discomfort (3 to 11 patients, p = 0.014) and respiratory distress (1 to 17 patients, p < 0.001). Baseline PaO2 level
was the only significant predictor of the magnitude of PaO2 reduction (p < 0.001).
Conclusion: Wearing an N95 mask for 4 hours during HD significantly reduced PaO2 and increased respiratory
adverse effects in ESRD patients.
Key words: Blood gas analysis; Hemodialysis; Hypoxemia; Masks; Oxygen
J Formos Med Assoc 2004;103:624-8
The outbreak of severe acute respiratory syndrome
(SARS) worldwide was characterized by efficient
nosocomial transmission of the virus.1 The majority of
SARS cases were associated with transmission in health
care settings2 or related to hospital exposure.3 The
use of masks, either surgical or N95 type, was shown
to be effective in preventing transmission of SARS
from patients to healthy hospital staff.4 During the
epidemic and nosocomial spread of SARS from April
to June 2003 in Taiwan, more than 100 SARS patients
were hospitalized and treated at National Taiwan
University Hospital (NTUH).
During the outbreak, all medical staff were re-
quired to wear N95 masks when having close contact
with patients. Most end-stage renal disease (ESRD)
patients coming to our hospital thrice a week for
hemodialysis (HD) treatment wore N95 masks as well
due to a pervading fear of SARS. However, despite
the need for this precaution, there was a lack of data
on whether ESRD patients could safely tolerate the
use of N95 masks during HD. There were few previous
studies evaluating the physiological stress imposed by
N95 masks and these focused mainly on healthy young
men doing exercise.5 Our ESRD patients, on the other
hand, were generally much older. Although patients
lay quietly during HD with minimal physical activity,
these patients were more likely to have concomitant
pulmonary and/or cardiovascular disorders which
rendered them unfit to use respirators.6 HD patients
also frequently have anemia and left ventricular hyper-
trophy which greatly increase their cardiac work-
load.7 Oxygen supplementation is sometimes needed
in these patients during HD owing to angina pectoris
or congestive heart failure. This study investigated
the impact of wearing N95 masks during HD on ESRD
patients and whether these patients could safely
tolerate the use of this kind of mask as a respiratory
protective device during an HD session.
N95 Masks During Hemodialysis
J Formos Med Assoc 2004 Vol 103 No 8 625
Methods
Patients
ESRD patients who received regular HD at NTUH
between April to June 2003 were invited to join the
study. Patients were considered eligible for the
study if they met the following inclusion criteria: 1)
had facial contours that permitted good fitting of N95
masks; 2) used either an arteriovenous (AV) graft or
fistula but not a venous catheter for vascular access;
3) did not depend on oxygen supply during previous
HD sessions; 4) did not breathe through a tracheos-
tomy; and 5) were willing to wear an N95 mask con-
tinuously throughout an HD session. Patients who
had subjective respiratory distress or an arterial oxygen
saturation (SaO2) level below 92% measured by a pulse
oximeter before the start of the study were excluded.
Baseline demographic and clinical characteristics of the
participants including age, gender, cause of renal
failure and comorbid conditions were recorded.
Comorbid condition referred to diseases other than
renal failure present at the time of study. This research
was approved by the institutional review board of this
hospital, and informed consent was obtained from
each participant before entry into the study.
Methods
At the start of the study before wearing the N95 mask,
vital signs were measured, including blood pressure,
pulse rate and respiratory rate. Clinical symptoms,
including headache, dizziness, tiredness, facial itchi-
ness, nasal stuffiness, decreased ability to concentrate,
chest discomfort or respiratory distress were recorded
if present. The severity of the symptoms was subjective-
ly graded by the patients as ‘mild’, ‘moderate’ or
‘severe’. A new disposable N95 mask (Model 8210;
3M, Occupational Health and Environmental
Safety Division/3M, St. Paul, Minnesota, USA) was
then put on and fixed tightly by each participant
under the supervision of the physician in charge
according to instructions of the manufacturer. Slight
self-adjustment of the mask was allowed during the
HD session. As soon as the N95 mask had been placed,
2 HD needles were inserted into the patient’s AV
shunt, one at the arterial end and the other at the
venous end. Using a 2-mL syringe which had been
rinsed with a small amount of heparin, 2 mL of blood
from each patient was drawn from the arterial end
of the AV shunt at the start of the dialysis. Trapped air
was rapidly expelled from the syringe. The syringe
needle was immediately replaced by a plastic plug
which prevented gas movement between the air
and the blood. The syringe with the blood drawn was
then put into an ice bath.8 Arterial blood gas (ABG)
including partial pressure of oxygen (PaO2) and
partial pressure of carbon dioxide (PaCO2) was ana-
lyzed by a blood gas machine (Bayer, USA) within
30 minutes after the blood had been drawn, and
represented the patient’s baseline blood gas levels.
Hematocrit level was also obtained at the beginning
of the dialysis.
All patients received bicarbonate dialysate and
non-cuprophan dialyzer membranes for HD. Vital
signs were monitored carefully during the whole
HD session, which lasted for 4 hours. At the end of
the dialysis, clinical symptoms and their severity were
reassessed. Vital signs were rechecked and ultra-
filtration volume was recorded. Another 2 mL of blood
was drawn from the arterial end of the AV shunt with
a new syringe. ABG was again analyzed using the
same method and machine within 30 minutes, and
represented the blood gas levels after prolonged
use of an N95 mask. All parameters including vital
signs, clinical symptoms and ABG were measured twice
for each patient: once before the use of the N95 mask
and once after.
Statistical analysis
The primary outcome measure was the change in
PaO2 level before and after the use of the N95 mask.
Secondary outcome measures included changes in
PaCO2, vital signs, and clinical symptoms. Mild hypo-
xemia was defined as a PaO2 level less than 80 mm Hg
and equal to or greater than 70 mm Hg, while PaO2
levels of less than 70 and 60 mm Hg represented
moderate and severe hypoxemia, respectively. Data
in the following categories were considered as out-
lying and excluded from the analysis: 1) a PaO2 level
equal to or greater than 130 mm Hg and 2) a PaCO2
level greater than 70 mm Hg after the use of an N95
mask. Paired t tests were conducted to compare the
baseline and the post-HD vital signs as well as blood
gas levels. Changes in clinical symptoms were analyzed
using Wilcoxon signed rank test. Univariate linear
regression was used to investigate the effect of various
potential risk factors on the amount of change in PaO2
level. For the clinical variables in which significant
differences between the baseline and the post-HD
were demonstrated, univariate as well as multivariate
regressions were performed to identify their predic-
tors. The risk factors examined included age, gender,
diabetes mellitus (DM), cardiovascular disease, base-
line vital signs (pulse rate, respiratory rate, systolic
blood pressure, diastolic blood pressure), hematocrit
level, and ultrafiltration volume. A p value of less
than 0.05 was considered statistically significant;
all tests were 2-tailed. The statistical analyses were
performed with the statistical package SAS for
Windows (Version 8.0).
T.W. Kao, K.C. Huang, Y.L. Huang, et al
626 J Formos Med Assoc 2004 Vol 103 No 8
Results
Fifty patients received HD regularly at our hospital
during the study period. Nine of these patients were
considered ineligible for the study for the follow-
ing reasons: 2 could not wear an N95 mask tightly
due to small faces; 3 were dialyzed via double-lumen
catheters; 3 depended on oxygen supply during
previous HD; and 1 breathed through a tracheostomy.
Another 2 patients who had respiratory distress before
the start of the study were excluded. A total of 39
eligible patients (23 men, 16 women) were included
in the study after informed consent was obtained.
Their mean age was 57.2 years (range, 25 to 88 years).
Ten of them (25.6%) had DM and 14 (35.9%) had
cardiovascular disease. The mean ultrafiltration
volume was 2.43 L, and the mean hematocrit level
was 32.9%.
About 70% of the subjects had a reduction in
PaO2 at the end of the 4-hour study period. Seven
(19%) patients were found to have various degrees of
hypoxemia — mild in 4 patients, moderate in 2, and
severe in 1. The mean PaO2 level dropped signifi-
cantly from 101.7 ± 12.6 (mean ± SD) mm Hg at
baseline to 92.7 ± 15.8 mm Hg at post-HD with a
net decrease of 9.0 ± 18.5 mm Hg (p = 0.006) [Fig.].
This reduction was not correlated with age, gender,
the presence of DM or cardiovascular disease, ultra-
filtration volume or hematocrit level. The baseline
PaO2 level was the only significant predictor of the
magnitude of PaO2 reduction (linear regression:
standardized B = -0.524, t = -3.74, p < 0.001). However,
among the 7 patients who developed hypoxemia, 6
were over 60 years old, and 3 had underlying cardio-
vascular disease. There was no significant change in
PaCO2 levels (baseline: 39.7 ± 4.3 mm Hg; post-HD;
40.7 ± 3.2 mm Hg; change: 1.0 ± 4.1 mm Hg; p = 0.136)
after wearing an N95 mask for 4 hours.
Changes in vital signs before and after prolonged
use of an N95 mask are shown in Table 1. Respiratory
rate increased significantly after wearing an N95
mask for 4 hours (p < 0.001). There was no significant
change in pulse rate or blood pressure.
Symptoms experienced by patients wearing N95
masks are shown in Table 2. Wearing an N95 mask
during HD significantly increased the incidence of
chest discomfort (p = 0.014) and respiratory distress
(p < 0.001). No significant risk factor for these clinical
symptoms could be identified.
Discussion
This study is the first to evaluate the physiological
impact of wearing N95 masks during HD on patients
with ESRD. Our investigation demonstrated that
wearing N95 masks for 4 hours during HD resulted
in a PaO2 reduction in the majority (70%) of patients
and caused various degrees of hypoxemia in nearly
Table 2. Symptoms before and after the use of N95 masks
in 39 patients with end-stage renal disease undergoing
hemodialysis.
Symptom Before mask use After mask use p value
(no. of patients ) (no. of patients)
Headache 2 2 1.000
Dizziness 2 6 0.289
Tiredness 7 6 1.000
Chest discomfort 3 11 0.014
Respiratory distress 1 17 < 0.001
Decreased ability to 2 4 0.688
concentrate
Ear pain 0 5 0.063
Facial itchiness 2 3 1.000
Nasal symptoms 3 2 1.000
Others 0 2 0.500
Table 1. Vital signs before and after the use of N95 masks in 39 patients with end-stage renal disease undergoing hemodialysis.
Variable Before mask use (mean ± SD) After mask use (mean ± SD) p value
Pulse rate (/min) 81.6 ±10.0 78.3 ±10.4 0.078
Respiratory rate (/min) 16.8 ±2.8 18.8 ±2.7 < 0.001
Systolic pressure (mm Hg) 136.3 ±30.8 142.3 ±32.9 0.165
Diastolic pressure (mm Hg) 75.4 ±15.4 79.1 ±16.1 0.113
SD = standard deviation.
Fig. Changes in partial pressure of oxygen (PaO2; A) and partial
pressure of carbon dioxide (PaCO2; B) levels before and after
prolonged use of N95 masks during hemodialysis in end-stage
renal disease patients. NS = not significant. * p < 0.05.
A) B)
40 20
30
40
50
60
60
80
100
120
140
Before After
*
NS
Before After
PaO
2
level (mm Hg)
PaCO
2
level (mm Hg)
N95 Masks During Hemodialysis
J Formos Med Assoc 2004 Vol 103 No 8 627
one-fifth of all ESRD patients. It also increased the
occurrence or severity of respiratory adverse effects
as indicated by an increase in the respiratory rate, and
the frequency of chest discomfort and respiratory
distress.
The use of a control group was not feasible in this
study because all patients treated with HD at NTUH
during the SARS epidemic wore N95 masks. One may
argue that factors other than wearing N95 masks could
have caused similar changes in PaO2 levels and
respiratory symptoms/signs. However, this was less
likely due to several reasons. Firstly, all of our patients
used bicarbonate type dialysate and biocompatible
membranes in the HD treatment. We avoided using
acetate dialysate and bioincompatible membranes
which had been previously reported to be associated
with the development of intradialytic hypoxemia.9–12
Moreover, if HD-related hypoxemia does occur, it is
commonly observed during the first 2 hours of HD
only.13,14 Therefore, the reduction in PaO2 levels in
our study was unlikely to have been due to these 2
factors. In addition, our patients lay on a bed through-
out the dialysis session, thereby minimizing the
possibile confounding effects of physical activities or
environmental factors. On the other hand, ‘statistical
regression towards the mean’ could not explain the
finding that all indicators of respiratory adverse
effects underwent significant changes in a consistent
pattern while all other non-respiratory parameters
were unaffected. Due to the same reason, psycho-
logical effects such as anxiety could not explain the
study results because other indicators of psychological
distress such as pulse rate did not show a significant
change. All evidence from this study indicated that
there had been a genuine increase in respiratory
adverse effects (i.e., PaO2 reduction, increased
respiratory rate, and increased frequency of chest
discomfort and respiratory distress) and that wearing
an N95 mask was the responsible cause.
There have been few previous studies evaluating
the physiological stress imposed by the wearing of N95
masks and these focused mainly on healthy young men
doing exercise.5 In a study by Jones, both respiratory
rates at rest and during exercise increased significantly
under the use of N95 masks. An addition of dead air
space was thought to be the main cause. Heart rate
also increased as work intensity increased, but was
significant only at heavy levels of work and during the
recovery stage. Systolic blood pressure showed a
biphasic change due to the use of N95 masks, being
significantly lower at rest and higher at high levels of
work. Air temperatures immediately anterior to the
face were, on average, 7.5°C higher.5 Similar to Jones’
study, respiratory rates of our HD patients also
significantly increased after wearing the N95 mask
for 4 hours. However, the heart rates of our patients
did not change significantly, probably because they
were lying on a bed during HD with minimal physical
activity. The small number of cases might also have
contributed to this insignificant result (p = 0.078).
Also, blood pressure of our patients did not change
significantly after wearing an N95 mask for 4 hours.
Previous study found that blood pressure usually
decreased gradually during HD due to a continuous
ultrafiltration of excess body fluid.15 This suggests
that wearing a mask may have significantly increased
blood pressure even though control values could not
be assessed.
Workers who wear respirators may complain of
symptoms such as headache, facial pain,16 thermal
discomfort,17 anxiety,18 local skin reaction,16 and
decreased visual field.19 In comparison, the most com-
mon symptoms experienced by our patients after
wearing N95 masks for 4 hours were respiratory
distress and chest discomfort, followed by ear pain
and dizziness. Among the 7 patients who developed
hypoxemia, 3 developed both respiratory distress
and chest discomfort, while 2 developed respiratory
distress and dizziness. The appearance of various
symptoms in these patients showed compatibility with
the occurrence of hypoxemia.
Several limitations in our study should be
noted. The hypoxemia results might have been under-
estimated as slight adjustment of the N95 masks by
the patients themselves was permitted during HD,
especially when facial itchiness occurred. This might
have allowed a small amount of air exchange which
led to a higher post-HD PaO2 level and/or a lower
PaCO2 level. This implies that the adverse respiratory
effect of wearing N95 masks might have been more
prominent than observed. However, our results re-
flected the real-life situation that HD patients would
sometimes adjust their masks during HD, especially
after prolonged use. Another limitation in our study
was that the sample size was relatively small. Inadequ-
ate statistical power might have been a reason for
insignificant results in the risk factors analysis.
Compared with other respirators, N95 masks are
relatively comfortable, light, and flexible and can
accommodate a variety of facial contours.20 They
interfere less with speech and visual acuity, and need
not be maintained or cleaned. These advantages make
the N95 mask a suitable candidate as a protective
device against respiratory-transmitted infections.
However, the benefits gained by reducing the mor-
bidity or mortality of a target infectious disease must
be weighed against the potential for immediate and
severe adverse effects on respiratory functions. Our
study showed that wearing an N95 mask for 4 hours
during HD in patients with ESRD caused a significant
T.W. Kao, K.C. Huang, Y.L. Huang, et al
628 J Formos Med Assoc 2004 Vol 103 No 8
increase in respiratory adverse effects, with nearly
one-fifth of patients developing hypoxemia. Our
results suggest that a significant number of patients
would develop clinically significant respiratory distress
if there was large-scale implementation of prolonged
use of N95 masks. Patients who are elderly and/or
have compromised cardiopulmonary functions are
expected to be at particularly high risk for develop-
ing respiratory distress, and they should be closely
monitored when using N95 masks.
In conclusion, our study showed that wearing N95
masks for 4 hours during HD in patients with ESRD
caused a drop in PaO2 level in 70% of patients. The
baseline PaO2 level was a significant predictor of the
amount of PaO2 reduction. Hypoxemia developed in
nearly one-fifth of patients. Respiratory rate and the
occurrence of chest discomfort and respiratory dis-
tress also significantly increased. As wearing an N95
mask in patients with ESRD during HD resulted in a
significant increase in respiratory adverse effects,
policy-making regarding a prolonged use of N95
masks in this patient group should take these potential
negative impacts into consideration.
ACKNOWLEDGMENTS: We would like to thank the
Ta-Tung Kidney Foundation and Mrs. Hsiu-Chin
Lee Kidney Research Fund for supporting this
investigation.
References
1. CDC. Severe acute respiratory syndrome—Singapore, 2003.
MMWR 2003;52:405-11.
2. CDC. Severe acute respiratory syndrome—Taiwan, 2003. MMWR
2003;52:461-6.
3. Booth CM, Matukas LM, Tomlinson GA, et al: Clinical features
and short-term outcomes of 144 patients with SARS in the
greater Toronto area. JAMA 2003;289:2801-9.
4. Seto WH, Tsang D, Yung RWH, et al: Effectiveness of precautions
against droplets and contact in prevention of nosocomial trans-
mission of severe acute respiratory syndrome (SARS). Lancet
2003;361:1519-20.
5. Jones JG: The physiological cost of wearing a disposable
respirator. Am Ind Hyg Assoc J 1991;52:219-25.
6. Martyny J, Glazer CS, Newman LS: Respiratory protection. N
Engl J Med 2002;347:824-30.
7. Nicholls AJ: Heart and Circulation. In: Daugirdas JT, Blake PG,
Ing TS, eds. Handbook of dialysis. 3rd ed. USA: Little, Brown
and Company; 2001:583-600.
8. Pierce LNB: Guide to mechanical ventilation and intensive
respiratory care. USA: W.B. Saunders Company; 1995:259-62.
9. Smit JC, Jones JG: Oxygen saturation during hemodialysis. Ren
Fail 1993;15:239-45.
10. Thews O: Computer analysis of hypoxemia during hemodialysis.
Artif Organs 1991;15:454-61.
11. Francos GC, Besarab A, Burke JF, et al: Dialysis-induced
hypoxemia: membrane dependent and membrane independent
causes. Am J Kidney Dis 1985;5:191-8.
12. Davidson WD, Dolan MJ, Whipp BJ, et al: Pathogenesis of dialysis-
induced hypoxemia. Artif Organs 1982;6:406-9.
13. Munger MA, Ateshkadi A, Cheung AK, et al: Cardiopulmonary
events during hemodialysis: effects of dialysis membranes and
dialysate buffers. Am J Kidney Dis 2000;36:130-9.
14. Ozdemir O, Arik N, Ozcebe O, et al: Evidence for the role of
dialysis hypoxemia in the pathogenesis of hemodialysis-induced
rise in tissue-type plasminogen activator. Thromb Res 1992;67:
697-704.
15. Zoccali C, Dunea G: Hypertension. In: Daugirdas JT, Blake PG,
Ing TS, eds. Handbook of dialysis. 3rd ed. USA: Little, Brown
and Company; 2001:466-76.
16. Szeinuk J, Beckett WS, Clark N, et al: Medical evaluation for
respirator use. Am J Ind Med 2000;37:142-57.
17. DuBois AB, Harb ZF, Fox SG: Thermal discomfort of respiratory
protective device. Am Ind Hyg Assoc J 1990;51:550-4.
18. Morgan WP: Psychological problems associated with the wearing
of industrial respirators: a review. Am Ind Hyg Assoc J 1983;44:
671-7.
19. Kraut A: Industrial respirators: certifying the worker. Am Fam
Phys 1988;37:117-26.
20. 3M Occupational health and safety products division: 3M
occupational health and safety products. St. Paul, Minn: 3M, 1986.
... Most of the conducted studies were performed on healthy or patient volunteers during normal working days, domestic life, regular outpatient control, and routine treatment applications. Although the symptoms caused by various mask applications appear to be similar, the reflections of this similarity on vital signs or blood parameters show conflicting results [13][14][15]. ...
... Studies conducted so far have mostly included healthy volunteers, outpatients who come to the clinic for control, or stable patients under routine treatment [14][15][16]. In the study they conducted on 39 patients during hemodialysis, Kao et al. observed that the partial oxygen pressure of patients wearing N95 masks decreased, their respiratory rate increased, and they had chest discomfort [14]. ...
... Studies conducted so far have mostly included healthy volunteers, outpatients who come to the clinic for control, or stable patients under routine treatment [14][15][16]. In the study they conducted on 39 patients during hemodialysis, Kao et al. observed that the partial oxygen pressure of patients wearing N95 masks decreased, their respiratory rate increased, and they had chest discomfort [14]. In 97 COPD patients who applied to the regular outpatient clinic, it has been observed that if the N95 mask is used, the SpO 2 of the patients during the effort decreased, the PEtCO 2 increased, and the feeling of discomfort worsened proportional to the severity of the disease [15]. ...
Article
Background: There are conflicting data on the effects of masks on vital signs and end-tidal CO2 (EtCO2) values in the literature. Aims: This study aims to evaluate the changes in the vital parameters and EtCO2 values of the patients who were administered oxygen through nasal cannula (NC) and simple oxygen mask (SOM) and wore surgical masks (SM) on top during their treatment. Methods: The prospective, observational study was conducted from January 2021, over consecutive 30 days, in the emergency department of a tertiary-care university hospital. The vital signs and EtCO2 values of the subjects administered O2 were noted at the time of arrival and at the 30th and 120th minutes of treatment. Changes in vital signs and EtCO2 values were compared with regard to NC-SM and SOM-SM applications over a 120-min study period. Results: Sixty-eight subjects were included in two groups (NC-SM [n = 49] and SOM-SM [n = 19]). At the 120th minute, a decrease in systolic and diastolic blood pressure, heart rate, and respiratory rate and an increase in oxygen saturation were observed in the group including all subjects. After decreasing slightly in the first 30 min, the EtCO2 value remained stable. Conclusions: NC-SM and SOM-SM applications do not affect adversely, and even seem to lead to recovery of, the vital signs and EtCO2 values during 120 min in subjects with acute complaints.
... It is a well-known fact that masks worn for longer hours at a stretch can cause hypoxemia and can affect our health [39]. A study on surgeons has shown that even an hour of wearing surgical masks elevate the pulse rates and lower the arterial pulsation oxygen saturation (SpO 2 ), indicating a possibility of a large decrease of PaO 2 (partial oxygen pressure of arterial blood) [38]. is effect is exacerbated at ages above 35 years in both men and women. ...
... A study on surgeons has shown that even an hour of wearing surgical masks elevate the pulse rates and lower the arterial pulsation oxygen saturation (SpO 2 ), indicating a possibility of a large decrease of PaO 2 (partial oxygen pressure of arterial blood) [38]. is effect is exacerbated at ages above 35 years in both men and women. Another study on end-stage renal disease patients showed that wearing N95 mask during haemodialysis to prevent SARS infection reduced PaO 2 and resulted in hypoxemia in majority of the patients [39]. PaO 2 < 50 mm Hg leads to hypoxemia. ...
Article
Full-text available
Background. Mask wearing can restrict the spread of respiratory viral transmission during the third wave of the COVID-19 pandemic. Globally, governments have emphasized its use in workplaces and public areas to prevent the transmission routes of corona virus. In spite of the current awareness in the general population, the stringency of wearing the mask lies as an individual’s choices. Subject and Methods. This research work discusses available studies on the types and comparison of masks in the market for use. It includes a short survey conducted with 1,173 anonymized healthy participants primarily devoid of comorbidities. The survey includes the effects of mask wearing, while outdoor with minimal activities like walking and with mild activities like jogging and stretching. Our research further discusses various health effects of wearing a mask, including cardiac output, hypoxemia, hypoxia, and dyspnoea, and how such situations that pose a threat can be consciously avoided. Results. It was found that the majority of people use cloth/fabric reusable mask. There remains scope for better-designed masks and improving health in the mass population by inculcating healthy breathing habits and other relevant exercises that can help people cope up better in this fight against the deadly virus at a larger scale. Conclusion. For most of the survey questions, there was significant correlation between gender and the related responses as there was no significantly observable difference in the nonparametric, unpaired analyses of responses. The main objective of this research work is to initiate more discussions and enhance awareness in natural ways of staying healthy during the pandemic emphasizing mask use. Further progress in this aspect remains a whole new area for future exploration.
... Based on a study that examined the physiological impact of wearing an N95 mask during hemodialysis, 8 with a sample size of 41 pairs (of observations), we have 85% power and a level of significance of 5% (two-sided) for detecting a mean of differences of 9.0 mmHg in PaO 2 between pairs, assuming a standard deviation of the differences to be 18.5. ...
... 9 In 2004, during the severe acute respiratory syndrome (SARS) outbreak in Taiwan, Kao et al investigated the physiological impact of wearing an N95 respirator during hemodialysis on 39 patients with end-stage renal disease.70% of participants had a reduction in the partial pressure of oxygen in arterial blood (PaO 2 ), and 19% developed various degrees of hypoxemia. 8 The physiological effect of N95 respirators among healthcare professionals was investigated by Rebmann et al, who demonstrated a small but significant increase in CO 2 levels among ten intensive care unit nurses who used N95 respirators for 12-hour shifts. 10 Although CO 2 concentration differences were not statistically significant in our study, there was an upward trend after a 4-hour shift. ...
Article
Objective: The objective of the current study was to determine gas exchange abnormalities and physiological changes among healthcare workers during a 4-hour emergency department (ED) shift while wearing the N95 respirator. Methods: Single-center prospective observational study. Comparisons of paired measurements were performed using a non-parametric Wilcoxon matched-pairs signed-rank test. Results: 41 subjects were included. Prolonged N95 respirator use was associated with a significant decline in plasma pH [7.35mmHg vs. 7.34mmHg, P=0.02], PvO2 [23.2 mmHg vs. 18.6 mmHg, P<0.001] and a concurrent increase in EtCO2 [32.5mmHg vs. 38.5mmHg, p<0.0001]. PvCO2 and bicarbonate levels did not differ. No significant change was observed for heart rate or oxygen saturation. Conclusion: Using an N95 respirator for prolonged periods by healthcare professionals may provoke changes in gas exchange. The clinical significance of these changes remains to be determined.
... Another recent report showed that the use of FFP2 respirators by healthcare professionals significantly increased EtCO 2 and FiCO 2 pressure values [6]. There are also reports indicating no significant physiological change after 1 h of mild-to-moderate effort with FFRs [4,6,8,19,21,22]. However, in these studies, participants were only tested for 1 h of exercise at a low-to-moderate workout rate under laboratory conditions. ...
Article
Introduction: The purpose of the present study was to assess nasal mucociliary clearance (NMC) and sinonasal symptoms of healthcare professionals wearing filtering facepiece-3 (FFP3) respirators. Methods: This prospective cross-sectional study was conducted at a large tertiary care academic center. Thirty-four healthcare professionals working at a coronavirus disease-19 patient care unit were included in the study. Visual analog scale (VAS) scores of sinonasal symptoms (nasal discharge, postnasal discharge, nasal blockage, hyposmia, facial pain/pressure, facial fullness, headache, fatigue, halitosis, cough) and the NMC times of the participants were assessed immediately before wearing FFP3 respirators and after 4 h of work with FFP3 respirators. Results: The mean age of the participants was 28.82 ± 4.95 (range, 26-31) years. Twenty participants were female and 14 were male. After wearing the FFP3 respirators for 4 h, a statistically significant increase was observed in total VAS scores for all sinonasal symptoms and NMC times (p < 0.001). When the VAS score of each sinonasal symptom was evaluated separately, a statistically significant increase was found for VAS scores of nasal discharge, postnasal discharge, nasal blockage, hyposmia, facial pain/pressure, and facial fullness (p < 0.05). Conclusion: The present study shows that nasal mucosal functions might be affected significantly after 4 h of using FFP3 respirators. The long-term effects and clinical significance of these short-term changes should be investigated on healthcare professionals in further studies.
... Yapılan bazı çalışmalarda N95 maske ve koruyucu ekipman kullanımıyla ilişkilendirilen kalp atım hızındaki artışın sebepleri arasında maskenin oluşturduğu solu-num direnci, çalışma temposu, kişinin fiziksel durumu ve formu, kişinin kaygı durumu ve CO 2 seviyesine bağlı olabileceği bildirilmiştir. 1,21,22 Çalışmaya katılan diş hekimlerinin meslek itibariyle uzun süreli maske kullanımına alışkın olmaları, yaş ortalamasının yüksek olmaması ve beden kitle indekslerinin riskli seviyelere yakın olmaması gibi sebeplerden dolayı kalp atım hızları ve satürasyon değerlerinde anlamlı değişimlerin olmadığını düşünmekteyiz. ...
Article
Amaç: Bu çalışmanın amacı, COVID-19 pandemisi boyunca yapılan dental işlemlerde uzun süre N95 maske kullanımının, diş hekimlerinin oksijen satürasyon değerleri ve nabız atım hızları üzerindeki etkisini değerlendirmek ve kullanım boyunca oluşan subjektif şikayetleri belirlemekti. Gereç ve Yöntem: Çalışmaya N95 maskesi kullanan 21-65 yaş (ortalama 31.43±9.44) arası toplam 60 (24 erkek ve 36 kadın) gönüllü diş hekimi dahil edildi. Satürasyon ve nabız kayıtları, N95 maskesi kullanılmadan önce ve 6 saat sürekli kullanımdan sonra parmak tipi puls oksimetre kullanılarak kaydedildi. Katılımcılara mide bulantısı, baş ağrısı, baş dönmesi, görme bozukluğu, nefes darlığı, çarpıntı, bilinç bulanıklığı, iletişim zorluğu, yorgunluk, nefes kokusu, maske-nem, sıcaklık ve kaşıntı ile ilgili soruları içeren subjektif semptomları 1-10 arasında puanlandırdıkları ölçme testi yapıldı. Bulgular: Kullanım öncesi ve 6 saat boyunca N95 takılması sonrasında, başlangıç ve sonuç oksijen satürasyon değerleri arasında istatistiksel olarak anlamlı bir değişiklik görüldü (1. gün: p=0.012 ve 3. gün: p=0.02). Ancak bu farklılık klinik olarak anlamlı değildi. Katılımcıların N95 kullanımı sonrasında nabız değerlerine bakıldı ve istatistiksel olarak anlamlı farklılık görülmedi (p=0.455, p=0.479, p=0.053). Erkeklerde maske içinde oluşan nem, sıcaklık ve karşılıklı iletişim zorluğu şikayetleri, kadınlarda ise nem, sıcaklık ve kaşıntı şikayetleri nispeten yüksek skorlar aldı. Kadın grubunun mide bulantısı, görme bozukluğu, sıcaklık ve kaşıntı skorları erkeklere göre istatistiksel olarak anlamlı şekilde yüksekti (p=0.001). Sonuç: N95 maskesinin 6 saat sürekli kullanımı diş hekimlerinin oksijen satürasyon ve nabız atım değerlerinde klinik olarak anlamlı bir etki göstermedi. Kadınlarda mide bulantısı, görme bozukluğu, sıcaklık ve kaşıntı şikayeti değerleri erkeklere göre daha yüksek görüldü.
... Some recent clinical reports have addressed the adverse effects induced by N95 mask use both in various patient populations and in frontline healthcare providers. While N95 face masks reportedly impair cardiopulmonary exercise capacity in medical staff, they might also impose physiological stress on some parameters during dialysis, such as hypoxemia, reduced PaO 2 , increased respiratory distress, and rate as well as chest discomfort [15,16]. Among the most frequent complaints by healthcare providers concerning respiratory protection equipment are headache, facial sensitivity, persistent erythema, and acne [17]. ...
Article
Full-text available
Background: Wearing face shields and masks, which used to have very limited public use before the COVID-19 outbreak, has been highly recommended by organizations, such as CDC and WHO, during this pandemic period. Aims: The aim of this prospective study is to scrutinize the dynamic changes in vital parameters, change in end tidal CO2 (PETCO2) levels, the relationship of these changes with taking a break, and the subjective complaints caused by respiratory protection, while healthcare providers are performing their duties with the N95 mask. Methods: The prospective cohort included 54 healthcare workers (doctors, nurses, paramedics) who worked in the respiratory unit of the emergency department (ED) and performed their duties by wearing valved N95 masks and face shields. The vital parameters and PETCO2 levels were measured at 0-4th-5th and 9th hours of the work-shift. Results: Only the decrease in diastolic BP between 0 and 9 h was statistically significant (p = 0.038). Besides, mean arterial pressure (MAP) values indicated a significant decrease between 0-9 h and 5-9 h (p = 0.024 and p = 0.049, respectively). In terms of the vital parameters of the subjects working with and without breaks, only PETCO2 levels of those working uninterruptedly increased significantly at the 4th hour in comparison to the beginning-of-shift baseline levels (p = 0.003). Conclusion: Although the decrease in systolic blood pressure (SBP) and MAP values is assumed to be caused by increased fatigue due to workload and work pace as well as increase in muscle activity, the increase in PETCO2 levels in the ED healthcare staff working with no breaks between 0 and 4 h should be noted in terms of PPE-induced hypoventilation.
... A significant impact of the N 95 respirator mask on cognitive impairment leading to severe errors while performing tasks was evident from previous studies [22]. Moreover, the use of N-95 mask was associated with health problems like headache, nausea, vomiting, and giddiness due to hypoxemia, hypercapnia, and mechanical factors or the stress associated with its use [19,23]. Routine cleaning and moisturization of skin with emollients at least one hour before using facial PPE, wearing of facial PPE correctly, and selection of correct size are recommended as some strategies to prevent adverse events related to facial PPE [24]. ...
Article
Introduction Accurate use of personal protective equipment (PPE) is an essential part of infection prevention and control measures to protect health care workers and patients from various hazardous conditions. Health care workers caring for patients with potentially infectious health conditions are using PPE for long periods of time. However, long-term use of PPE can cause many physiological health hazards among health care workers. So, the current study was carried out to assess the general health problems and dermatological problems experienced by health care workers with PPE use. Materials and methods A descriptive cross-sectional survey has been carried out in two selected tertiary care hospitals in central India by recruiting 301 health care workers. Non-probability convenient sampling technique was used to select participants for the study. Sociodemographic Performa and structured questionnaires were used to collect data on demographic characteristics of the participants and various health problems experienced by health care workers with PPE use. Collected data were analyzed using appropriate descriptive and inferential statistics. Results The current study reported excessive sweating (86.4%), difficulty in reading (85%), dry mouth (80.7%), and breathing difficulty (74.1%) as the most common problem associated with PPE use. In addition to this, adverse reactions like headache, restlessness, and dizziness were reported by 70.1%, 64.5%, and 50.8%. Indentation and pain on the back of the ears (76.1%), skin soaking (67.1%), and excessive sweating (76.1%) were identified as the most common problems related to N-95 masks, gloves, and coverall use. Conclusion The current study revealed a higher incidence of various health problems with PPE use among health care workers. The findings of the study highlight the importance of developing various guidelines to reduce the negative impact of PPE use and implementing preventive measures to decrease health problems associated with PPE use.
... Many researchers have reported that health care providers wearing a mask may experience headaches and nasal pressure, 12,13 and N95 respirators can reduce PaO 2 in patients with end-stage renal disease. 14 In healthy subjects, wearing masks during short-term moderate-intensity aerobic exercise is associated with an increase in end-tidal carbon dioxide (EtCO 2 ). 15 The perianesthesia nursing areas have been impacted by COVID-19. ...
Article
Objective: This study assessed oxygen saturation variation and comfort in adult surgical patients wearing masks in PACU during the COVID-19 epidemic. Design: Retrospective observation was applied in this study. Methods: One hundred thirty-seven patients wearing no medical masks (Group A, aged from 20 to 87) and 136 patients wearing medical masks (Group B, aged from 18 to 91) were selected in this retrospective study after extubation in PACU. After extubation their pulse oxygen saturation, noninvasive mean blood pressure and heart rate were recorded at two different time points (treated with 40% O2 oxygen therapy for 10 minutes and breathing room air for 10 minutes). The comfort, arterial blood gas data, complications and duration of patients were also reviewed in PACU. Findings: There were no significant differences in the pulse oxygen saturation between the two groups after inhaling 40% O2 or air. Compared with Group A, patients in Group B have lower comfort (6 [4-7] vs 7 [6-8]; P < .001), with shortened duration after extubation in PACU (50 [45-55] vs 56 [48-60]; P < .001). No significant differences were found in heart rate, noninvasive mean blood pressure, arterial blood gas data and complications. And no hypoxemia and respiratory adverse events happened in two groups. Conclusions: Wearing medical masks does not reduce oxygen saturation in adult surgical patients during recovery from general anesthesia. The discomfort caused by masks is the concern in PACU.
Article
In the past, the use of face masks in western countries was essentially limited to occupational health. Now, because of the COVID-19 pandemic, mask-wearing has been recommended as a public health intervention. As potential side effects and some contraindications are emerging, we reviewed the literature to assess the impact of them in daily life on patient safety and to provide appropriate guidelines and recommendations. We performed a systematic review of studies investigating physiological impact, safety, and risk of masks in predefined categories of patients, which have been published in peer-reviewed journals with no time and language restrictions. Given the heterogeneity of studies, results were analyzed thematically. We used PRISMA guidelines to report our findings. Wearing a N95 respirator is more associated with worse side effects than wearing a surgical mask with the following complications: breathing difficulties (reduced FiO2, SpO2, PaO2 increased ETCO2, PaCO2), psychiatric symptoms (panic attacks, anxiety) and skin reactions. These complications are related to the duration of use and/or disease severity. Difficulties in communication is another issue to be considered especially with young children, older person and people with hearing impairments. Even if benefits of wearing face masks exceed the discomfort, it is recommended to take an “air break” after 1–2 h consecutively of mask-wearing. However, well-designed prospective studies are needed. The COVID-19 pandemic could represent a unique opportunity for collecting large amount of real-world data.
Article
Introduction The use of personal protective equipment increased rapidly during the COVID-19 pandemic that began in 2019. The purpose of this study was to examine the effects of uninterrupted 4-hour use of internationally certified nonvalved filtering facepiece respirators on venous blood gas in health care workers during the COVID-19 pandemic. Methods A before-after design included venous blood gas analyses collected at the beginning of shifts before nonvalved filtering facepiece respirator had been put on and after 4-hour uninterrupted use of nonvalved filtering facepiece respirator. Results In this study, 33 volunteer health care workers took part. In terms of blood gas values, mean pCO2 values were 47.63 (SD = 5.16) before and 47.01 (SD = 5.07) after nonvalved filtering facepiece respirator use, mean HCO3 values were 23.68 (SD = 1.10) in first blood gas analysis and 24.06 (SD = 1.31) in second blood gas analysis, and no significant difference was observed between before and after the use of nonvalved filtering facepiece respirator (t = 0.67, P = .50, t = −2.0, P = .054, respectively). The only significant difference in parameters investigated between the groups was in pH levels, at pH = 7.35 (SD = 0.29) before and pH = 7.36 (SD = 0.20) after nonvalved filtering facepiece respirator use (t = −2.26, P = .03). Conclusion Continuous nonvalved filtering facepiece respirator use for 4 hours was not associated with clinician impairment in blood gas and peripheral SpO2 levels during nonexertional clinical ED work.
Article
The purpose of a respirator is to prevent the inhalation of harmful airborne substances or to provide a source of respirable air when breathing in oxygen-deficient atmospheres. For a physician to recommend the use of respirator, general background information on respiratory-protective devices is required. The first part of this clinical practice review describes the general aspects of industrial hygiene, respirators and a respirator-certification program. The second part addresses matters related to medical certification for respirator use.Medical certification for respirators is an important part of the activities of the occupational physician. To determine whether a worker is able to tolerate the added strain of a respiratory protective device is a complex process in which factors such as fitness for work, health of the individual, characteristics of the work itself, and the properties, type, and requirements of the respiratory protective device, have to be considered. Medical certification is of utmost importance for respirator use, and it should be viewed as an element in a comprehensive respiratory protection program. A comprehensive program is the key element in affording the workers' effective respiratory protection once the initial steps of the hierarchy of methods of hazard control have proved insufficient or infeasible. As a result, the need for the industrial hygiene/safety officer, the worker, the employer and the medical professional to work as a team is much more than in any other field of occupational medicine—a necessary requirement for making the right decision. Am. J. Ind. Med. 37:142–157, 2000. © 2000 Wiley-Liss, Inc.
Article
Sumario: The use of a disposable respirator is associated with significant physiological costs, especially at moderate and heavy work loads. This paper quantifies some of the physiological costs of using a single-use disposable respirator. Specifically, published information is lacking with regard to resistance to breathing, cardiopulmonary effects, and heat stress imposed by disposable respirators
Article
It is well known that hemodialysis (HD) causes a rise in plasma tissue-type plasminogen activator (t-PA). Although there have been several suggested mechanisms responsible for this effect of HD, the precise cause has not been well understood yet. Another complication of HD, when performed with acetate-containing dialysate, is hypoxemia, which is commonly observed during the first hour of the session. The purpose of this study was to investigate the relationship between dialysis hypoxemia and HD-induced t-PA changes during the first two hours of HD. HD caused significant increase in plasma t-PA antigen levels. When individual t-PA profiles versus time were examined, two patterns were observed. Whilst ten subjects (%56) experienced minimal or no increase, t-PA antigen level of the remaining eight subjects began to rise at 30 minutes and continued at that level up to 90 minutes, when the last samples were drawn. The courses of pO2 were also different; whilst the former group had "early-onset and short-term" hypoxemia, the latter had "late-onset and prolonged" hypoxemia. The amount of increase in t-PA antigen and the amount of decrease in pO2 were correlated at 60 and 90 minutes of the HD session. Thus, it is concluded that dialysis hypoxemia may contribute to HD-induced rise in plasma t-PA levels. Further studies comparing different dialysates and dialyser membranes are required to confirm this hypothesis.
Article
Arterial oxygen partial pressure decreases during hemodialysis if acetate as buffer is used or if certain types of bioincompatible dialyzer membranes are used. Several hypotheses considering the main cause of this hypoxemia have been proposed. To gain more insight into the mechanisms leading to this hypoxemia, a mathematical model for the computerized simulation of exchange processes during hemodialysis has been used. To simulate the ventilation-perfusion ratio (VA/Q), a simplified two-compartment model of the lung has been applied. The simulation results reveal that hypoxemia during hemodialysis has two reasons. In acetate hemodialysis, the main cause is a shift of the CO2-bicarbonate equilibrium caused by "consumption" of hydrogen ions during acetate metabolization resulting in hypoventilation due to a decrease in CO2 partial pressure. During hemodialysis with bioincompatible dialyzer membranes, the hypoxemia may be explained by an increase in inhomogeneity of the VA/Q ratio in the lung. The loss of CO2 and bicarbonate into the dialysate during acetate hemodialysis has only a minor effect on arterial PO2 and cannot explain the observed hypoxemia. The decrease of O2 diffusing capacity during hemodialysis with bioincompatible membranes has only a negligible effect on the arterial PO2. The simulation results show also that the venous PO2 in the brain may fall below a critical level of less than 25 mm Hg, thereby possibly causing oxygen deficiency in the cortex.
Article
Respiratory protective devices which would protect the wearer against noxious material and gases are not worn in many of the appropriate circumstances. They have been said to feel uncomfortable and hot. In the present study, six men and six women in a 25 degrees C room reported on facial discomfort, thermal sensation, and sweating while wearing three different types of half-facepiece respirators requiring tidal airflow. Skin temperature of the face was measured using a thermocouple taped to the nasolabial fold. The subjects reported that the face felt comfortable when the skin temperature was 34 degrees C or below. However, at skin temperatures above 34.5 degrees C, the face felt increasingly warm, uncomfortable, and sweaty. This finding is similar to that reported previously when subjects wore a half-facepiece respirator supplied continuously with warm, humid air. The conclusion is that thermal conditions of the face contributed to, and may possibly dominate, the discomfort of wearing respiratory protective devices.
Article
The Occupational Safety and Health Act requires medical evaluation of workers prior to certification for industrial respirator wear. For proper evaluation, the physician must understand the physiologic effects of respirators, the stresses of the work and the health of the worker. Most of the information needed to make certification decisions can be obtained from the history, the physical examination and observation of the worker exercising while wearing a respirator. Pulmonary function testing or cardiac stress testing may be helpful in difficult cases.
Article
Hypoxemia during hemodialysis may result from several differing processes. We initially studied patients undergoing standard acetate hemodialysis. At 15 minutes of dialysis, leukopenia (primarily neutropenia), a decline of platelet count, and hypoxemia occurred, but without a significant change in mean minute ventilation. Complement activation (V/A ratios of C5a greater than 1.0) persisted throughout dialysis. Leukocyte count returned to baseline by one hour. To separate the effects of solute and/or gas fluxes from those of blood-membrane interaction we studied changes in Po2, WBC, C5a, TxB2, and PGI2 during a period of blood membrane interaction without dialysis, and during subsequent acetate dialysis. Patients were studied with both polyacrylonitrile (PAN) and cuprophan membranes containing different priming solutions during membrane contact alone. Despite leukopenia and complement activation, hypoxemia failed to occur during membrane contact alone. At 15 minutes of subsequent acetate dialysis, significant hypoxemia occurred with both membranes. However, the degree of hypoxemia was twice as great with a cuprophan membrane primed with acetate (18.6 +/- 3.3 mm Hg) compared with air or bicarbonate (9.1 +/- 1.4 and 7.0 +/- 2.0 mm Hg, respectively), or compared with PAN (8 +/- 2.8 mm Hg). Changes in thromboxane B2, PGI2, and C5a did not correlate with changes in Po2. We conclude that there are two major components to dialysis related hypoxemia. One is membrane independent, and may relate to the metabolic effects of acetate or to dialyzer CO2 loss. The remaining portion is membrane dependent, occurring with cuprophan, but not with PAN, and is conditioned by an acetate dependent interaction between blood and membrane.
Article
This review has dealt with the psychological problems associated with the use of industrial respirators. The need for men and women to wear various self contained breathing apparatus (SCBA) while working in hostile environments such as toxic and oxygen deficient atmospheres is well documented. Extensive research has been carried out in an attempt to improve the design of respirators, and major advances have resulted in the manufacture of SCBA that insure health, safety, and performance. Indeed, recent research reveals that performance decrements associated with the wearing of respirators are due entirely to pak weight; that is, breathing resistance no longer appears to be a significant problem in most cases. Despite the fact that major advances have taken place in the design of respirators, it is still widely recognized that "psychological" problems continue to exist. Unfortunately, very little research has been directed toward an understanding of the "person" component of the respirator-person interface; that is, research has focused on respirator variables with little attention paid to person variables. While it has been proposed that certain "types" of individuals be eliminated from work tasks requiring the wearing of SCBA, there has not been a concise diagnostic statement presented to enable such a screening approach to be adopted.
Article
Patients undergoing hemodialysis with acetate-containing dialysis solutions develop hypoxemia. To determine the cause of the hypoxemia, we studied and compared the ventilatory, gas-exchange and blood-gas responses in chronic renal failure patients undergoing hemodialysis with acetate and bicarbonate dialysis solutions. Seven stable chronic dialysis patients were dialyzed against acetate and bicarbonate solutions in a random order. Dialysis was carried out using a 1.5 m2 hollow fiber dialyzer at a blood flow rate of 200 ml/min and a dialysate flow rate of 500 ml/min. During acetate dialysis, PaO2 fell within 15 minutes from a mean control predialysis concentration of 84 = 6 (SEM) mmHg to a mean of 70 +/- 7.5 mmHg (P less than 0.05), and remained low throughout the study. PaO2 did not change significantly during bicarbonate dialysis. Total ventilation fell from a predialysis level of 7.2 +/- 0.7 L/min to 5.7 +/- 0.6 L/min within 15 minutes (P less than 0.05). PaCO2 was not significantly changed from predialysis levels with either acetate or bicarbonate dialysis. Measurement of blood concentration of CO2 and bicarbonate across the dialyzer indicated that the total CO2 loss (as CO2 and bicarbonate) through the dialyzer was 3 millimoles per minute or the equivalent of approximately 60 ml of CO2 per minute, i.e., about one third of the patient's metabolic production of CO2.