Obesity and risk of peri-operative complications in
children presenting for adenotonsillectomy
Olubukola O. Nafiua,*, Glenn E. Greenb, Sarah Waltona, Michelle Morrisa,
Sudheera Reddya, Kevin K. Trempera
aDepartment of Anesthesiology, University of Michigan, Ann Arbor, MI, USA
bPediatric Otorhinolaryngology, University of Michigan, Ann Arbor, MI, USA
Received 27 July 2008; received in revised form 21 September 2008; accepted 28 September 2008
Available online 8 November 2008
International Journal of Pediatric Otorhinolaryngology (2009) 73, 89—95
Background: Adenotonsillectomy (T&A) is a very common surgical procedure in
children. With the rising prevalence of childhood overweight and obesity, our goal
was to describe the prevalence of overweight/obesity in children presenting for T&A
in our institution. We also sought to compare the frequency of peri-operative
complications and the likelihood of being admitted following T&A between over-
weight/obese and normal weight children.
Methods: We examined our peri-operative database and extracted clinical, demo-
January 2005 and February 2008. Children were classified into normal weight, over-
factors contributing to the likelihood of admission following T&A.
Results: The overall prevalence of overweight and obese was 20.7%. Overweight/
obese children were more likely to have intra-operative desaturation (p = 0.004),
multiple attempts at laryngoscopy (p < 0.001), difficult mask ventilation (p = 0.001),
and post-induction and post-anesthesia care unit (PACU) upper airway obstruction
(p < 0.001). Additionally, overweight and obese children were more likely to be
admitted following T&A. BMI showed a moderate positive correlation with post-
operative length of stay (LOS). Multiple logistic regression analysis showed that BMI
and presence of medical co-morbidities were independent predictors of LOS.
of peri-operative complications and are more likely to be admitted and stay for longer
than their healthy weight peers.
Published by Elsevier Ireland Ltd.
* Corresponding author. Department of Anesthesiology, University of Michigan, Room UH 1H247, Ann Arbor, MI 48109-0048, USA.
Tel.: +1 734 936 4280; fax: +1 734 936 9091.
E-mail address: email@example.com (O.O. Nafiu).
0165-5876/$ — see front matter. Published by Elsevier Ireland Ltd.
During the last three decades, the United States
(US) has witnessed a tripling of the prevalence of
childhood obesity making this an ongoing clinical
and public health crisis . This secular trend in the
prevalence of obesity means that an increasing
number of children presenting for anesthesia and
surgery will be either overweight or obese. We
recently showed that 31% of the pediatric surgical
population at our institution was either overweight
or obese .
Adenotonsillectomy (T&A) is one of the most
common major surgical procedures performed in
children . Conservative estimates are that about
300,000 T&A are performed annually in the US .
Additionally, T&A is often performed for sympto-
matic relief of obstructive sleep apnea (OSA), a
condition that is more prevalent in overweight
and obese children . Only a few studies have
examined the subject of obesity in children present-
ing for T&A [6,7]. However these studies had small
sample sizes and only focused on the ‘‘morbidly
obese child’’. There are currently no data specifi-
cally describing the prevalence of overweight and
obesity or the likelihood of peri-operative compli-
cations in this group of patients. Therefore, our
study had two objectives: (1) to describe the pre-
valence of overweight and obesity in children pre-
senting for T&A, and (2) to examine the association
between BMI and peri-operative complications in
the same group of patients.
The University of Michigan Institutional Review
Board (Ann Arbor, MI) approved this retrospective
review of our clinical information system (Centri-
city1General Electric Healthcare, Waukesha, WI).
This system was designed to serve not only clinical
purposes, but also to collect data for observational
research studies and it includes a structured, elec-
tronic pre-operative history and physical on every
patient. Data are entered by residents, attending
anesthesiologists, and certified registered nurse
anesthetists (CRNA) as part of routine clinical
duties. We reviewed data for the period between
January 1 2005 and February 1 2008. We extracted
the following data on all children who underwent
T&A during the study period: age, gender, ethnicity,
American Society of Anesthesiology (ASA) classifica-
tion, height and weight. We routinely measure
height and weight of all children prior to anesthesia
and elective surgery at our institution. Body mass
index (BMI) wascalculated asweightinkgdividedby
the square of the height in meters (BMI = kg/m2).
(BMI < 85th percentile), overweight (BMI > 85th
and < 95th percentile), or obese (BMI ? 95th per-
centile) using age and gender-specific reference
growth charts from the National Center for Health
Statistics (NCHS)/Centers for Disease Control and
Prevention (CDC) .
The indications for T&A such as recurrent tonsil-
litis, sleep disordered breathing (SDB) were noted.
SDB was defined by history of habitual loud snoring
with or without observed cessation of breathing by
the parents or caregivers. The proportion of over-
weight and obese patients between male and
female patients was compared. We also noted the
presence of medical co-morbidities such as hyper-
tension, bronchial asthma and diabetes. These diag-
noses were based on the parents or caregivers’
report at the time of surgery or from the patient’s
described under several broad headings. Airway
complications included difficult mask ventilation
(measured using a four-point scale previously
described by Han et al. ), difficult laryngoscopy
(defined by Cormack and Lehane  grade >2),
more than one attempt at laryngoscopy (multiple
laryngoscopy), significant desaturation (defined by
any recorded intra-operative SPO2 value < 90%),
and dental injury. All desaturation events were
recorded by continuous pulse oximetry. Anesthesia
care in our facility is 100% supervised by attending
pediatric anesthesiologists. The method and choice
of induction of anesthesia is at the discretion of the
attending staff. Typically the first attempt at mask
ventilation and laryngoscopy are performed by an
anesthesiology resident, a pediatric anesthesia fel-
low, or a nurse anesthetist. In all cases mask venti-
lation was accomplished with a disposable, clear
plastic mask (King Systems Corporation Noblesville,
IN), while laryngoscopy was performed with a fiber-
optic laryngoscope handle and blade (Heine Inc.,
requirement of oral or nasal airway adjuvant to
maintain airway patency. Hypertension was defined
as history of or use of anti-hypertensive medica-
tions. Diabetes was defined based on the use of oral
hypoglycemic agents or insulin. The length of stay
(LOS) following surgery was noted. LOS was mea-
sured in days; and a value of zero meant the child
was discharged on the day of surgery. Additionally
because majority (76%) of patients were same-day
discharge (after a few hours PACU stay), we dichot-
omized LOS into admitted or not for ease of inter-
group comparison. Correlation coefficients between
LOS and BMI, age, SDB diagnosis (yes or no) and
90O.O. Nafiu et al.
presence or absence of co-morbidities were also
because these are routinely admitted following T&A
in our institution. We also excluded children with
secondary causes of obesity such as Prader-Willi
syndrome, Cushing’s syndrome or the nephrotic syn-
drome from the study. Children with chronic lung
disease and those with concurrent surgical proce-
dures that could prolong the duration of anesthesia
and surgery were also excluded.
3. Statistical analysis
Data analysis was carried out with SPSS V.15.0 (SPSS
ing means, standard deviations and percentages
were calculated for the demographic and anthropo-
metric data. Pearson’s Chi-square for categorical
variables and one-way ANOVA were used to examine
age and gender differences in the distribution of the
descriptive variables. Correlation coefficients were
calculated using LOS as a dependent variable and
BMI, age, gender, SDB, and presence or absence of
medical co-morbidity as independent variables. Mul-
tiple logistic regression models were constructed for
the dependent variable and the independent vari-
alpha level of 0.05 (two-tailed) was selected to
indicate statistical significance.
After excluding 18 records due to incomplete BMI
data, we analyzed the data on 2170 children who
had T&A. There were 1210 (55.8%) males and 960
(44.2%) females. The mean age of the population
was6.5 ? 4.1
19.1 ? 5.2 kg/m2. The prevalence of overweight
was 13.1% and obesity was 7.5%. As expected, BMI
showed a moderate positive correlation with age
(r = 0.53,p < 0.001)intheentirecohortofpatients.
There was no significant difference in the preva-
lence of overweight or obesity between male and
female patients (14.1% vs. 12.6% for overweight and
7.2% vs. 6.2% for obesity; , p > 0.05). The majority
Obesity and risk of peri-operative complications in children 91
Demographic and clinical characteristics of healthy weight and overweight/obese adenotonsillectomy
Healthy weight (n = 1714) Overweight/obese (n = 456)
Race/ethnic categories (N)
Indication for surgery (%)
Medical co-morbidities (%)
Post-op disposition (%)
Values are means (S.D.) unless otherwise stated.
*p < 0.05 (comparisons done with one-way ANOVA for continuous variables or Pearson’s Chi-square test for categorical variables).
**p-Values < 0.001 (comparisons done with one-way ANOVA for continuous variables or Pearson’s Chi-square test for categorical
yHispanic, Asian, Native American, or unspecified. SDB, sleep disordered breathing.
(75.3%) of patients were discharged within 24 h of
days and had a mean (S.D.) of 1.6 days (0.8 day).
admitted than normal weight children (F = 14.04,
df = 2, p < 0.001). Among those admitted, BMI
showed a slight positive correlation with LOS
(r = 0.20,p < 0.001).Forthesampleof2170patients,
61.9% had a pre-operative diagnosis of SDB. Pre-
operative diagnosis of SDB and overweight/obesity
p < 0.001). Patients with a pre-operative diagnosis
without a history of SDB (21.2% vs. 30.0%, X2
p = 0.003).Atthesametime,pre-operativediagnosis
of hypertension and diabetes were more frequent in
overweight/obese than in normal weight children
(Table 1). The distribution of other demographic
and clinical parameters is shown in Table 1. The
overall incidence of difficult laryngoscopy (Cormack
and Lehane grades 3 or 4) was 12.3%. There was
however no significant difference in the proportion
of children with difficult laryngoscopy between the
healthy weight and overweight/obese children
(Table 2). A higher proportion of overweight/obese
children required multiple attempts at laryngoscopy
than their healthy weight peers (27.4% vs. 11.9%;
p < 0.001). There was a highly significant difference
in the incidence of post-induction desaturation
between overweight/obese and healthy weight
ing the association between LOS and age, BMI, pre-
sence or absence of SDB and presence or absence of
medical co-morbidities is shown in Table 3. Interest-
ingly LOS was not significantly correlated with age;
although the other parameters showed mild to mod-
erate correlation with LOS.
We constructed a logistic regression model to
predict the likelihood of admission (LOS), based
on age, BMI, presence of medical co-morbidity,
and presence of SDB (Table 4). The results showed
that BMI (p < 0.001) and presence of medical co-
morbidities (p < 0.05) were the only independent
predictors of LOS.
Our data shows that certain peri-operative compli-
cations (predominantly airway-related) are more
92 O.O. Nafiu et al.
senting for adenotonsillectomy.
Frequency of peri-operative complications between healthy weight and overweight/obese children pre-
ComplicationsHealthy weight (n = 1714)Overweight/obese (n = 456)p-Value
Grade 1 mask ventilation
Grade 2 mask ventilation
Upper airway obstruction
All values generated with Pearson’s Chi-square test. PACU, post-anesthesia care unit; RSI, rapid sequence induction.
Pearson correlation coefficients for factors associated with LOS (n).
Parameter LOS BMI
LOS, Length of stay; BMI, body mass index; SDB, sleep disordered breathing.
*p < 0.05.
**p < 0.001.
frequent in overweight/obese children presenting
for T&A than their healthy weight counterparts. We
have also shown that the prevalence of overweight
and obesity is high in this group of children and that
whereas majority of children were discharged on
the same day following T&A, overweight/obese
children were more likely to be admitted and to
have longer post-operative LOS than their lean
peers. As the prevalence of overweight and obesity
continues to increase in American children , it is
reasonable to expect that an increasing number of
children presenting for a surgical procedure like
T&A will be either overweight or obese. The pre-
valence of overweight/obese observed in the pre-
sent study is about 10% lower than estimates in the
general pediatric population  and in our pre-
viously published data  of the general pediatric
surgical population. This observation could be a
reflection of the known association of ATH and
SDB with growth failure [11,12]. Some of the
patho-physiologic explanations for growth failure
in children with ATH and SDB include, increased
sleep energy expenditure, nocturnal hypoxemia,
alkalosis and impaired growth hormone secretion
[13,14]. Our finding of overweight/obesity preva-
lence of 20% in this study may however reflect a
changing trend in the growth dysfunction in children
with ATH:where growthfailure usedtobeafeature,
overweight/obesity is becoming increasingly com-
Very few studies have looked at the incidence of
peri-operative complications in obese children pre-
senting for T&A [15,16]. These studies either did not
primarily study overweight and obese children or
only focused on obese children with OSA. Most also
had comparatively smaller sample size. Our findings
however concurred with these studies that airway
complications are common in the peri-operative
period in children presenting for T&A. To date the
most clearly defined risk factors for post-T&A com-
plications have been OSA and presence of medical
co-morbidity . Our study shows that overweight
and obesity are important pre-operative risk factors
in these children. Children with higher BMI are also
likely to require oro-pharyngeal airway to maintain
airway patency following induction of general
anesthesia, they are more likely to require multiple
attempts at laryngoscopy and have a higher inci-
dence of significant desaturation. While it may be
argued that the skill of the laryngoscopist could
affect the documented incidence of difficult airway,
we have no reason to suspect that the effect of
operator skill will only operate on the overweight or
obese children. In all likelihood and in routine clin-
ical practice, the more experienced laryngoscopist
is often responsible for managing the airway in
patients with potentially difficult airway. Unfortu-
nately we do not have a record of the years of
experience of the residents and nurse anesthetists
involved in the care of the patients in this study.
Overweight and obese children presenting for T&A
therefore deserve extra vigilance in the peri-opera-
tive period including use of airway adjuvant, having
optimal airway management equipments on hand
and supplemental oxygen administration in the
Our finding of a higher prevalence of pre-existing
medical co-morbidities such as hypertension and
diabetes in overweight/obese children agrees with
published observations by others [17,18] and our-
selves in the general pediatric surgical population
. There is still no data on how these medical co-
morbidities contribute to peri-operative outcome in
children. There is clearly a need to prospectively
study the impact of these diseases on the peri-
operative outcome in children with the ultimate
goal of identifying risk factors for complications.
Consistent with published data, majority of
patients in this study were discharged within a
few hours of surgery [20—22]. Ambulatory T&A is
now established to be a safe procedure in most
patients. The duration of hospital stay following
T&A varies from a few hours to several days .
Previously published factors associated with admis-
sion after T&A include age less than 3 years, OSA
with significant polysomnographic desaturation,
post-operative pain, dehydration, bleeding and pre-
sence of craniofacial disorders [3,20]. To our knowl-
on the likelihood of admission and the post-opera-
tive LOS following T&A in children. Our findings
suggest that BMI is an independent predictor of
likelihood of admission following T&A. This may
be related to the higher prevalence of OSA in obese
children and the fact that this group has a higher
incidence of peri-operative complications .
Despite the well-documented benefits of day case
AT: reduced hospital cost, reduced waiting time and
may be prudent to advise parents of overweight and
Obesity and risk of peri-operative complications in children 93
whether patients are admitted or not (LOS) after
Regression coefficients for model predicting
S.E. Wald X2
SDB, sleep disordered breathing, BMI, body mass index.
obese children about an increased possibility of
their child being admitted following T&A.
Some limitations of the present study deserve
consideration. Since this was a retrospective study,
mechanisms used to explain outcome differences
between overweight, obese and normal weight chil-
dren can only be speculative. It should also be noted
that we used a clinical diagnosis for SDB. While we
realize that overnight polysomnography (PSG) is the
gold standard for OSA diagnosis [23,24]; this is an
expensive tool that is often not readily available. To
this end our institution and others  do not
routinely require pre-operative PSG in children
before T&A. Our clinical SDB diagnosis was based
on a history of habitual loud snoring which has been
shown to be a very useful screening tool: nearly all
habitual snorers have a positive sleep study . We
therefore applied a clinically relevant and useful
pre-anesthetic tool to identify the children with
SDB. Future prospective studies should consider
pre-operative PSG for proper diagnosis of OSA in
One of the most vexing issues for the anesthe-
siologist is whether children with OSA should be
routinely admitted after general anesthesia and
surgery and if they are, how long the patient should
be monitored. Unfortunately,there are inconclusive
data in the literature to predict which patients can
be safely managed as an outpatient as opposed to
which requires mandatory admission and close mon-
itoring . It is commonly reported that early and
late respiratory complications occur frequently in
children with severe OSA following general anesthe-
sia and surgery . However, since many children
with SDB may not have had PSG prior to being
reviewed by the anesthesiologist, it may be neces-
sary to advise parents or caregivers about the pos-
sibility of prolonged PACU stay or even admission. It
is certainly prudent to suggest that children with
habitual snoring, who are obese or have other med-
ical co-morbidities should (when feasible) be
referred for overnight PSG to quantify the severity
of their OSA. Where PSG is impossible (for logistic or
fiscal reasons), obese children who are habitual
snorers deserves close monitoring after anesthesia
and surgery. Whether these children should all be
admitted overnight or longer remains to be seen.
In conclusion, we have shown in a large popula-
tion of children undergoing T&A, that overweight/
obese children were more likely to have airway-
related peri-operative complications than their lean
peers. Additionally, multiple regression analysis
confirmed the importance of BMI and presence of
medical co-morbidities in predicting the likelihood
of being admitted following T&A in children. With
the growing epidemic of childhood obesity, it is
prudent to assume that more children presenting
for T&A may be either overweight or obese and have
medical co-morbidities like diabetes, hypertension
and asthma and may therefore require in-patient
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