Evaluating Risk Factors for Pediatric Post-extubation Upper Airway Obstruction Using a Physiology-based Tool

Abstract

Rationale: Subglottic edema is the most common cause of pediatric extubation failure, but few studies have confirmed risk factors or prevention strategies. This may be due to subjective assessment of stridor or inability to differentiate supraglottic from subglottic disease.

Objectives: Objective 1 was to assess the utility of calibrated respiratory inductance plethysmography (RIP) and esophageal manometry to identify clinically significant post-extubation upper airway obstruction (UAO) and differentiate subglottic from supraglottic UAO. Objective 2 was to identify risk factors for subglottic UAO, stratified by cuffed versus uncuffed endotracheal tubes (ETTs).

Methods: We conducted a single-center prospective study of children receiving mechanical ventilation. UAO was defined by inspiratory flow limitation (measured by RIP and esophageal manometry) and classified as subglottic or supraglottic based on airway maneuver response. Clinicians performed simultaneous blinded clinical UAO assessment at the bedside.

Measurements and main results: A total of 409 children were included, 98 of whom had post-extubation UAO and 49 (12%) of whom were subglottic. The reintubation rate was 34 (8.3%) of 409, with 14 (41%) of these 34 attributable to subglottic UAO. Five minutes after extubation, RIP and esophageal manometry better identified patients who subsequently received UAO treatment than clinical UAO assessment (P < 0.006). Risk factors independently associated with subglottic UAO included low cuff leak volume or high preextubation leak pressure, poor sedation, and preexisting UAO (P < 0.04) for cuffed ETTs; and age (range, 1 mo to 5 yr) for uncuffed ETTs (P < 0.04). For uncuffed ETTs, the presence or absence of preextubation leak was not associated with subglottic UAO.

Conclusions: RIP and esophageal manometry can objectively identify subglottic UAO after extubation. Using this technique, preextubation leak pressures or cuff leak volumes predict subglottic UAO in children, but only if the ETT is cuffed.

Keywords: airway obstruction; artificial respiration; endotracheal; intubation; pediatrics.

Figure 1.

Details of the study protocol from the time of consent until study completion. Measurements required for the upper airway obstruction (UAO) tool are presented in light gray along the left side of the study protocol section. CPAP = continuous positive end-expiratory pressure; NIF = negative inspiratory force; RIP = respiratory inductance plethysmography.

Figure 2.

An example of supraglottic upper airway obstruction data of a 10-year-old patient after tonsillectomy and adenoidectomy. Data show improvement of flow limitation, less change in esophageal pressure, and increased flow during an airway maneuver. Esophageal pressure is measured in centimeters of water. RIP = respiratory inductance plethysmography.

Figure 3.

An example of subglottic upper airway obstruction data of a 4 month old after extubation. The data indicate severe inspiratory flow limitation (left) and no rise in flow despite continual decrease in esophageal pressure. There was no improvement with an airway maneuver (not shown), but significant improvement occurred 20 minutes after racemic epinephrine administration (right). Esophageal pressure is measured in centimeters of water. RIP = respiratory inductance plethysmography.

Figure 4.

Consolidated Standards of Reporting Trials diagram showing eligible, consented, and included patients. The overall consent rate was 77%. The most common reason for refusal of consent was related to parental discomfort regarding placement of the esophageal catheter. A total of 409 patients were included, with more patients having uncuffed than cuffed endotracheal tubes (ETTs). Available data derived from the upper airway obstruction (UAO) tool within the first 60 minutes after extubation were used to classify patients as having supraglottic UAO, subglottic UAO with UAO treatment, and no UAO (including nine patients with tool-gauged subglottic UAO who did not receive UAO treatment). There was an equal number of patients with subglottic UAO versus supraglottic UAO. Patients with subglottic UAO had the highest rates of reintubation and UAO treatment, although close to 50% of patients with supraglottic UAO received a UAO treatment.

Figure 5.

Post-extubation upper airway obstruction (UAO) rate (in distance-weighted least-squares analysis) as a function of age, stratified by subglottic and supraglottic UAO. Age was modeled as a continuous variable for this analysis, with 49 of 409 patients having subglottic UAO and 49 of 409 patients having supraglottic UAO. Subglottic UAO appears to peak near 18 months of age and is very uncommon after 8 years of age. Supraglottic UAO appears relatively constant throughout the pediatric age spectrum.