Perioperative respiratory adverse events (PRAEs) are the major cause of morbidity and mortality in pediatric patients undergoing anesthesia.1,2 PRAEs range from mild transient desaturation to severe life-threatening events with long-term sequelae.1,2
In our clinical practice, it appeared that African American (AA) pediatric patients experienced PRAEs more frequently than other ethnic groups. A thorough literature search did not reveal any studies in the anesthesia literature that address race/ethnicity as an independent risk factor for PRAEs. The otolaryngology literature reports 1 study that established AA ethnicity as a risk factor for respiratory complications after adenotonsillectomy.3 This was a retrospective cohort study conducted at Montreal Children’s Hospital. The findings determined that children of AA ethnicity were twice as likely to experience major respiratory complications after tonsillectomy and adenoidectomy (T&A) surgery. These researchers concluded that ethnicity may be an additional independent risk factor to consider when planning for T&A. Moreover, Thongyam et al4 prospectively evaluated demographic variables as predictors of postoperative complications; these researchers concluded that age <3 years and AA race are high risk factors for postoperative respiratory complications in children with obstructive sleep apnea syndrome undergoing adenotonsillectomy.
In lieu of recent reports of death and permanent neurological injury after tonsillectomy in children, Coté et al2 conducted an electronic survey and reviewed data from the American Society of Anesthesiologists (ASA) Closed Claims Project. Death and permanent neurological damage occurred in 77% of cases, and they concluded that at least 16 children could have been rescued if respiratory monitoring was continued longer. The data also revealed that a large percentage of severe adverse outcomes was related to respiratory events, and that children of AA ethnicity were at higher risk of having sleep apnea.2
Recent literature and evidence confirm the higher prevalence of obstructive sleep apnea in AA children, and these children also show less improvement postoperatively when compared to other races.5–7 This has been attributed to differences in craniofacial structure, respiratory drive, exposure to allergens and environmental toxins, and the higher incidence of obesity. It has been suggested that demographics may be considered as one of the parameters for elective admission postoperatively.4,7,8
The above-mentioned studies imply that demographic factors may be implicated in higher risk of morbidity and mortality in the perioperative period. However, although race/ethnicity has been cited as an increased risk for adverse events for tonsillectomies, it has not been investigated as an independent risk factor for PRAEs for all surgical procedures.
The primary aim of the study was to compare the incidence of PRAEs in the AA pediatric population versus other ethnic groups. We also analyzed other factors that can contribute to adverse perioperative respiratory outcomes. Specific factors that were considered include age, birth history (preterm versus full term), preexisting respiratory disease (asthma, recent pneumonia, recent/current upper respiratory infection [URI]), exposure to second-hand smoke, surgical procedure, extubation technique, and use of endotracheal tube versus laryngeal mask airway.
Delineation of risks that predispose pediatric patients to respiratory complications can guide perioperative management, especially for elective procedures. Moreover, aggressive perianesthetic optimization of high-risk patients can significantly improve outcomes.
METHODS AND DESIGN
A retrospective chart review was conducted after Institutional Review Board approval. Because this is a retrospective chart review, the need for obtaining informed consent was waived by the Institutional Review Board. Chart review was conducted from August 2013 to December 2013. A total of 1148 patients who met the inclusion criteria were selected, and charts were analyzed. Specifically, we reviewed intraoperative and postanesthesia care unit records for any documentation of desaturation (oxygen saturation [Spo2] <92% for ≥2 minutes), laryngospasm (as documented by anesthesia providers and as indicated by need for positive pressure ventilation or other intervention as documented—propofol or succinylcholine), bronchospasm (documentation of wheezing or use of bronchodilators), persistent cough, stridor, and reintubation. Any such episode of desaturation (Spo2 <92%), laryngospasm, bronchospasm, persistent coughing, or stridor requiring intervention or reintubation was defined as a PRAE.
Inclusion criteria included healthy ASA category I and II patients between 2 and 9 years of age undergoing outpatient surgical procedure lasting <4 hours. Any child with a known difficult airway or a syndrome associated with a difficult airway was excluded. Also, any child requiring supplemental oxygen was excluded. We chose to include relatively healthy children undergoing simple, outpatient procedures to eliminate any confounding factors that can predispose to the occurrence of PRAE.
Families identified their child’s racial identity during registration and were limited to the following selection: AA, Caucasian, Hispanic, Asian, Native American, or other. Data analysis also included other patient, surgery, and anesthesia specifics. Other patient characteristics that were identified included gestational age at birth, respiratory disease history, and exposure to second-hand smoke. Any documentation of current URI (symptoms present at the time of surgery) and recent URI (symptoms within 4 weeks of surgery) was also recorded. Medical encounter data included type of procedure by surgical subspecialty, the type of airway (tracheal tube, laryngeal mask airway, mask, or none), and for those who had tracheal tubes, whether they were extubated while under deep anesthesia or after emergence.
PRAEs were identified by reviewing intraoperative and postanesthesia care records for documentation of desaturation, laryngospasm, bronchospasm, reintubation, and any other respiratory complication requiring intervention.
The data were analyzed using statistical software R v3.1.2 (R Foundation for Statistical Computing, Vienna, Austria). Summary statistics were expressed as count and percentage for categorical variables. Fisher exact tests were performed to test the difference in respiratory adverse event rate between racial groups. To assess the impact of potential risk factors on respiratory adverse event, a univariate logistic regression model was fitted for the respiratory adverse event (yes/no) as a function of each risk factor. Multivariable analysis was conducted by building a logistic regression model that retained the race factor. All reported patient and procedural risk factors were considered in the model building process. A backward stepwise procedure was implemented to select variables using the 5% significance criteria. Effect of age was tested to be nonlinear, and it was categorized into 4 subgroups of about equal size. Interactions between race and other selected variables were tested to be insignificant and were not included in the model. P values ≤.05 were considered to indicate statistical significance.
The study was sized to detect the difference in incidence of respiratory adverse events between AA and Caucasian groups. A difference of 5% in incidence was considered of clinical importance. The clinical investigators who conducted this study provided the following estimates: the ratio between these 2 ethnicity groups in the database was about 1:4 and the incidence was about 9% and 4%, respectively. At the 5% significant level, a total number of 1075 patients provide the power of 80% for detecting a significant and clinically important difference in the incidence of adverse events between 2 groups using a z test for comparing 2 proportions.
We identified 1148 patients who met the inclusion criteria. Table 1 demonstrates the demographic distribution and other perioperative characteristics of the cohort. Of the 1148 patients, no patient had >1 anesthetic encounter. For the entire group, 62 (5.4%) children had ≥1 PRAEs (Table 2). Table 2 summarizes the overall incidence of PRAEs in AA and Caucasian children. Out of a total of 231 AA children, 26 had an adverse respiratory event, and out of a total of 777 children, 27 children experienced an adverse respiratory event. According to our results, the overall incidence of PRAE was 5.4% and the incidence of PRAE in the AA and Caucasian groups was 11.3% and 3.5%, respectively. There were 87 Hispanic children and 53 children of other race in the study cohort. There were 6 PRAEs reported in the Hispanic group and 3 PRAEs in the other race group, leading to incidences of 7% and 6%, respectively. The most common PRAEs included laryngospasm, desaturation, and bronchospasm (Table 2). PRAEs for AA and Caucasian children differ chiefly by the higher overall incidence of PRAEs and specifically a higher incidence of bronchospasm in the AA group.
We first performed exploratory univariate analysis on different variables to determine any association with a higher incidence of PRAEs. According to univariate analysis, variables associated with a higher frequency of PRAE were younger age, recent URI, and current URI. Among the surgical procedures, otolaryngology and orthodontic procedures had a higher than average rate of PRAE. The use of endotracheal tube and deep extubation technique were also associated with higher incidence of PRAE (Tables 3 and 4).
The adjusted effect of race was evaluated in a logistic regression model, controlling for significant confounding variables. Results of the logistic regression model were depicted in Table 5. The multivariable analysis provided strong evidence that AA children had a much higher chance of adverse events compared to Caucasian children (P < .001). The odds of having adverse events for AA children were 3.33 times the odds for Caucasian children (95% confidence interval, 1.74–6.37). Hispanic children did not have a significant difference in odds of adverse events compared to Caucasian children (P = .73). There was evidence that children 5 years of age or older had reduced risk of adverse events than children younger than 5 years of age. Compared to children younger than 5 years of age, the odds of adverse events for children 5–7 years of age and for children 7 years of age or older were 0.46 (P = .034) and 0.15 (P = .001), respectively. Children with a recent or current URI had a much higher chance of adverse events than children who did not have a URI (odds ratio [OR] = 10.79, P < .001 for recent URI; OR = 3.73, P = .003 for current URI). Regarding surgical procedures, otolaryngology and orthodontic procedures were associated with significantly higher odds of adverse events compared to other surgical procedures (OR = 4.80, P < .001 for otolaryngology; OR = 4.30, P = .005 for orthodontic). Extubation technique was another factor that was significantly associated with higher incidence of adverse events. The odds of adverse events for deep extubation were 2.45 times that for extubation in awake state (P = .007).
In the present study, the overall incidence of PRAEs was 5.4%. Our data revealed a significantly higher incidence of PRAEs in the AA pediatric population when compared to Caucasian patients. To our knowledge, this is the first study that addresses ethnicity as an independent risk factor for perioperative respiratory complications for all surgical procedures in the anesthesia literature.
We designed our study to include relatively healthy children (ASA categories I and II) undergoing outpatient surgical procedures. All patients with extensive medical history including extreme prematurity were excluded from the study. Also, patients undergoing complex or long duration surgical procedures were excluded. We included children between 2 and 9 years of age as it has been established that respiratory complications are more likely to occur in younger children.9 The inclusion criteria were developed to limit any confounding factors that could potentially contribute to an adverse outcome.
Our analysis revealed that AA pediatric patients had significantly higher incidence of PRAEs when compared with Caucasian patients. Furthermore, it showed that perioperative risk is also increased with younger age, recent or current URI, use of endotracheal tube, and deep extubation technique. As compared to other surgical procedures, otolaryngology and dental procedures were more likely to be associated with a higher incidence of PRAE. Previously identified risk factors for PRAE include age, presence of URI, use of endotracheal tubes, surgeries involving the airway, and history of asthma and obstructive sleep apnea.1,9,10 Most of these are in concordance with our results. Younger age, otolaryngology procedures, and the use of endotracheal tubes have been consistently reported to be associated with a higher risk of respiratory complications. Surprisingly, in the present study, recent URI was associated with a higher risk of respiratory problems as compared to acute URI. This has also been previously reported by Tait and Knight.11 We also evaluated the effect of body mass index (BMI) and asthma, as well as their interaction with race (Table 3). None of these achieved statistical significance. Therefore, the final logistic regression model did not include BMI, asthma, and their interaction with race (Table 5).
Our results indicate that deep extubation was associated with a higher incidence of respiratory adverse events. This is contradictory to previous studies that showed no difference in complication rates between awake and deep extubation.12–14 The present study was conducted at a tertiary-care pediatric teaching hospital with a very high case load. Our data do not differentiate between anesthesia provider roles, that is, anesthesia faculty versus resident physician versus certified registered nurse anesthetist. Another important factor is the skill of the registered nurse managing the patient in the postanesthesia care unit. Moreover, the technique of deep extubation was not standardized. A few of the previous studies that showed no difference in the rates of respiratory adverse events between deep and awake extubation groups were underpowered.12,13 Baijal et al14 reported no difference in the incidence of PRAEs in children undergoing a T&A after an awake versus deep extubation. However, because this was not a randomized study, there may have been selection bias where the more complex patients were extubated awake. The success of extubating a patient deep depends on patient factors, the experience of the anesthesia provider, and the infrastructure of the facility.
Limitations of the study are its retrospective design and dependence on accurate documentation. The retrospective nature of the study poses the potential for reporting bias. Another limitation of the study is that our data are from a single institution. However, despite these limitations, our data reveal a strong association between AA ethnicity and a higher risk of PRAEs even after adjusting for confounding factors.
Further research and prospective studies are needed to determine the cause for this increased risk of perioperative breathing complications in the AA population. Most likely, the causation is multifactorial, involving a complex interplay among genetic, morphological, physiological, and environmental factors.
Several previous studies have identified differences between Caucasians and AAs, both adults and children, regarding morphology and pathological processes that may contribute to this higher risk. AA ethnicity, as compared to Caucasians, has been found to be a significant independent risk factor for sleep apnea and sleep disordered breathing even after controlling for age, sex, and BMI.7,15 Evidence also reveals that the prevalence of asthma is higher in children of AA ethnicity even after adjusting for confounding variables such as socioeconomic status and environmental factors.16–18 AA children also tend to have more severe or poorly controlled asthma as reflected by their significantly higher rates of hospitalization for wheezing.13,19 Hence, not only is asthma more common in the AA pediatric population, these children are also afflicted with more severe disease. This is consistent with our finding of higher incidence perioperative bronchospasm observed in the AA pediatric group. Increased bronchial hyperreactivity in this group can account for this result. AA children are more likely to be overweight and/or obese as compared to Caucasian children.20 Actual differences in airway dimensions and lung function may also contribute to the increased risk of PRAE in AA children. Patel et al21 found that AA children tended to have narrower airways compared to Caucasian children, and that heritability patterns were similar in the 2 groups. Furthermore, other studies have identified that AA children have lower lung volumes when compared to Caucasian children.22,23 The basis for this difference is complex and involves many factors such as birth weight, anthropometric, socioeconomic, and nutritional factors.24
In conclusion, results of the present study suggest that race/ethnicity is an independent risk factor for PRAEs. However, prospective studies are needed to further investigate this correlation. It is imperative to identify patients at high risk for perioperative complications and recognize factors that further exacerbate this risk. Preoperative optimization and risk stratification are mandatory to improve outcomes. Timing of surgery (patient free of recent or acute sickness), avoidance of endotracheal tube when possible, and vigilant intraoperative and postoperative monitoring and escalation of care and hospital admission when required may minimize complications. A multidisciplinary approach should be adopted when caring for high-risk patients, and communication among the pediatrician, surgeon, and anesthesiologist is recommended to ensure safe patient outcomes.
Name: Sarah Tariq, MD.
Contribution: This author helped design and conduct the study, analyze the data, and write the manuscript.
Name: Madiha Syed, MD.
Contribution: This author helped conduct the study, analyze the data, and write the manuscript.
Name: Timothy Martin, MD.
Contribution: This author helped conduct the study and review the manuscript.
Name: Xu Zhang, PhD.
Contribution: This author helped conduct power analysis and multivariable analysis, and revise the manuscript.
Name: Michael Schmitz, MD.
Contribution: This author helped conduct the study, review the manuscript, and approve the final manuscript.
This manuscript was handled by: James A. DiNardo, MD, FAAP.
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