Although maintenance of the airway is an important aspect of the safe administration of anesthesia to children, upper airway obstruction and difficulty with intubation can occur in anesthetized, spontaneously breathing children, especially with obstructive sleep apnea syndrome (1,2).
In anesthetized, spontaneously breathing children, as well as adults, maneuvers such as chin lift and jaw thrust improve airway patency and ventilation (3). Sleep posture influences upper airway stability in patients with obstructive sleep apnea (4–6). Also, lateral position decreases collapsibility of the passive pharyngeal airway in anesthetized adult patients with obstructive sleep apnea (7). Moreover, the lateral decubitus position provides easy airway management and intubation for morbidly obese patients (8). We speculated that the lateral position combined with these maneuvers may improve airway patency and ventilation. We therefore studied the effects of these maneuvers and body position on airway patency in anesthetized children with obstructive sleep apnea syndrome, using clinical signs.
After obtaining the approval of our hospital review board and parents’ informed consent, we studied 30 children (aged 1–10 yr), with obstructive sleep apnea syndrome, scheduled for elective adenotonsillectomy. Children with craniofacial abnormalities, deformities of the chest or spine, and myopathies were excluded.
Each patient was premedicated with diazepam 0.5 mg/kg orally 1 h before anesthesia. Anesthesia was induced with 7% sevoflurane via a face mask with 100% oxygen from a circle system. After the induction, the patient was breathing spontaneously on inspired sevoflurane concentration of 5%. The patients had standard monitoring in place (noninvasive arterial blood pressure, electrocardiogram, pulse oximetry, end-tidal CO2, and anesthetic concentrations).
After 5 min of maintenance, the patient was placed into the neutral neck position (7). A baseline measurement was made with the face mask with the patient’s chin unsupported. Then chin lift was done with one hand without making the mandible protrude. The upper and lower molars contacted lightly, and the lip remained open under the neutral neck position and chin lift maneuver. Jaw thrust was applied with both hands, displacing the jaw upwards and anteriorly with the mouth open (Esmarch maneuver). Then, the patient was placed into the left lateral decubitus position (right side up). The head was supported by additional pillows so that the trunk and head were aligned. A baseline measurement under the lateral position was made in the neutral neck position with the patient’s chin unsupported. Chin lift and jaw thrust, described above, were done in the lateral position, respectively. The measurements of airway patency were performed consecutively twice in the same order (Fig. 1).
Two milliliters 4% lidocaine was sprayed onto the oropharynx, epiglottis, and trachea, and then the trachea was intubated without a neuromuscular blocking drug in the lateral position. After the patient was immediately placed to the supine position and tracheally extubated, the trachea was reintubated with the patient in the supine position.
Airway patency was assessed clinically as follows: stridor score 1 = normal breathing sounds detected by auscultation over the trachea, 2 = stridor over the trachea detected by stethoscope, 3 = stridor detected without auscultation (audible), 4 = no airway sound detectable over the trachea (2,3). Also, the degree of difficulty with intubation (intubation difficulty score) was rated in the lateral and supine positions as: Grade 1 = intubation easy, Grade 2 = intubation requiring an increased anterior lifting force and assistance to pull the right corner of the mouth upward to augment space, Grade 3 = intubation requiring multiple attempts and a curved stylet, Grade 4 = failure to intubate with the assigned laryngoscope (9).
Data were expressed as median (range). Stridor scores were analyzed by means of the nonparametric Friedman’s test for repeated-measure analysis. Post hoc multiple comparison tests were performed with Student-Newman-Keuls method. Intubation difficulty scores were analyzed with Wilcoxon’s signed rank test. P < 0.05 was considered statistically significant.
Twenty-two boys and 8 girls were included in this study: age, 4 (1–10) yr; weight, 16.5 (9–60) kg; height, 105.5 (75–146) cm. Table 1 shows the demographic characteristics of each child and the individual changes of stridor score using these manipulations.
We performed the measurements of airway patency twice in the same order as shown in Figure 1. The obtained scores in each manipulation on 19 children were the same; therefore, in the remaining 11 children we made these measurements once because of ethical reasons. The changes of stridor score are presented in Figure 2. Median stridor score was 4 (25%–75% interquartile range 3–4) at a baseline measurement. We also observed apparent thoracoabdominal asynchronous movement during the baseline measurement, but chin lift and/or jaw thrust improved the movement with stridor loud enough for everyone around the patients to notice in almost all cases (median score 3 [3–4] and 3 [2–3], respectively). Also, the lateral position per se improved airway patency from 4 (3–4) to 3 (2–3) like these airway maneuvers did. Moreover, the lateral positioning dramatically enhanced the effects of these maneuvers on airway patency from 3 (3–4) to 2 (2–3) in chin lift and from 3 (2–3) to 1 (1–1) in jaw thrust. Intubation difficulty scores were not different in these two positions (1 [1–2] and 1 [1–2] in the lateral position and the supine position, respectively).
Adenotonsillar hypertrophy is the most common cause of obstructive sleep apnea syndrome in children. Upper airway obstruction is a major challenge for anesthesiologists administering general anesthesia in patients with obstructive sleep apnea syndrome (1). When we anesthetize children with adenotonsillar hypertrophy in daily practice, we often encounter upper airway obstruction. Maneuvers such as chin lift and jaw thrust improve airway patency and ventilation in anesthetized, spontaneously breathing children as well as in adults (3). As shown in this study, however, these airway maneuvers alone may not be effective enough to provide a sufficient airway condition for children with adenotonsillar hypertrophy under deeper volatile anesthesia. Thus, some investigators have combined other manipulations, such as continuous positive airway pressure, with these airway maneuvers (2,3,10).
Traditionally, body position has influenced respiratory mechanics and breathing patterns. In fact, several studies investigated the effects of sleep posture on upper airway stability and showed that the lateral position increases stability to some extent (4,6). A study showed that the lateral position decreases collapsibility of the upper airway in patients with obstructive sleep apnea under general anesthesia (7). Also, the lateral decubitus position provides smooth induction and intubation for morbidly obese patients (8).
In the present study, we showed that lateral positioning increased the effects of common airway maneuvers and provided a sufficient airway patency for children with adenotonsillar hypertrophy. Because we did not observe the upper airway using a laryngoscopy or pharyngeal radiographs, we are not sure how these manipulations affected the upper airway. Based on the research of Isono et al. (7), the position shifting from the supine to the lateral might have enlarged both retropalatal and retroglossal airways, thereby improving stridor scores. We also investigated intubation conditions between the supine and lateral positions, and the intubation difficulty score in the lateral position was the same as that in the supine position. Taking these results into consideration, the lateral position can ease the airway management of children with sleep apnea syndrome as Aono et al. (8) showed in morbidly obese patients.
Generally, anesthesiologists who are confronted with a child with upper airway obstruction secondary to hypertrophied tonsils and/or adenoids will alleviate the obstruction by inserting an oral airway. However, inserting an airway could lead to airway complications such as laryngospasm, coughing, and breath-holding (11). Moreover, upper airway obstruction prevents anesthesia from becoming deeper and increases the risk of inserting the airway under light anesthesia, thereby causing airway complications. Therefore, lateral positioning could deepen anesthesia without an airway, thereby preventing such airway complications. Also, airway management in sedated children undergoing diagnostic procedures remains controversial (12). Maintenance of a patent airway is of critical importance in these cases. Thus, the present results are meaningful not only to anesthesiologists but also non-anesthesiologists, who often sedate children and are not accustomed to oral airway insertions.
A limitation of the methodology in this study is the failure to randomize between the chronological order of the positions by always testing the lateral position last. We investigated airway patency of the 19 patients using these maneuvers combined with the position changing consecutively twice in the same order, whereas the investigation was performed once in the remaining 11 patients because of the reproducibility of the results.
In conclusion, lateral positioning combined with common airway maneuvers significantly improved airway patency.
We thank Dr. Wasa Ueda, professor of Departments of Anesthesiology, Clinical Physiology and Pharmacology, School of Nursing, Kochi Medical School, for editorial support and Tatsuo Uchida of Office of Biostatistics, University of Texas Medical Branch for statistical suggestions.
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