A nasal cannula can be used to treat obstructive sleep apnea

Abstract

Rationale: Obstructive sleep apnea syndrome is due to upper airway obstruction and is associated with increased morbidity. Although continuous positive airway pressure efficaciously treats obstructive apneas and hypopneas, treatment is impeded by low adherence rates.

Objectives: To assess the efficacy on obstructive sleep apnea of a minimally intrusive method for delivering warm and humidified air through an open nasal cannula.

Methods: Eleven subjects (age, 49.7+/-5.0 yr; body mass index, 30.5+/-4.3 kg/m2), with obstructive apnea-hypopnea syndrome ranging from mild to severe (5 to 60 events/h), were administered warm and humidified air at 20 L/minute through an open nasal cannula.

Measurements and main results: Measurements were based on standard sleep-disordered breathing and arousal indices. In a subset of patients pharyngeal pressure and ventilation were assessed to determine the mechanism of action of treatment with nasal insufflation. Treatment with nasal insufflation reduced the mean apnea-hypopnea index from 28+/-5 to 10+/-3 events per hour (p<0.01), and reduced the respiratory arousal index from 18+/-2 to 8+/-2 events per hour (p<0.01). Treatment with nasal insufflation reduced the apnea-hypopnea index to fewer than 10 events per hour in 8 of 11 subjects, and to fewer than 5 events per hour in 4 subjects. The mechanism of action appears to be through an increase in end-expiratory pharyngeal pressure, which alleviated upper airway obstruction and improved ventilation.

Conclusions: Our findings demonstrate clinical proof of concept that a nasal cannula for insufflating high airflows can be used to treat a diverse group of patients with obstructive sleep apnea.

Figure 1.

Nasal cannula for delivery of warm humidified air to a patient (treatment with nasal insufflation). As can be seen, the cannula is designed to leave the nose open, and thus a patient can expire freely through the nose. Dimensions of the cannula are as follows: length, 1,800 mm; outer diameter, 5 mm. Dimensions of the tube after the Y piece: length, 440 mm each; inner diameter, 3.4 mm; dimension of the prongs, 5 mm (outer diameter, each nostril). The cannula has been designed to decrease any potential noise caused by the high flow of air, minimizing noise-induced sleep disruption.

Figure 2.

Airflow and supraglottic pressure (Psg) response to treatment with nasal insufflation (TNI) in one subject (subject 1). During baseline, with TNI off (left), large swings in supraglottic pressure and flattening of the inspiratory airflow contour occurred as supraglottic pressure continued to fall, indicating upper airway obstruction (left). Whereas TNI at 10 L/minute had no significant effect on airflow and supraglottic pressure swings (middle), TNI at 20 L/minute increased end-expiratory Psg from 0 to 2.2 cm H₂O, which was associated with an increase in peak inspiratory airflow from 290 to 360 ml/second, and respiratory effort markedly declined as indicated by reductions of the supraglottic pressure swings from −15 to −3 cm H₂O.

Figure 3.

Effect of treatment with nasal insufflation (TNI) on obstructive hypopneas in one subject during non–rapid eye movement (NREM) sleep. Left: TNI off. Right: TNI 20 L/minute. Horizontal lines below the flow signal demarcate individual hypopnea events with oxyhemoglobin desaturations of 4 and 3%, respectively. Note the marked decline in the snoring signal on TNI compared with TNI off. Microphone = digitally displayed snoring auditory signal; Psg = supraglottic catheter pressure (cm H₂O); Sa_O2 = oxygen saturation.

Figure 4.

Sleep-disordered breathing indices. Shown are apnea and hypopnea indices during the baseline (Bsl) diagnostic night and the clinical treatment night for individual subjects. Individual subject symbols are consistent between panels. TNI = treatment with nasal insufflation.

Figure 5.

Mechanism of action. Airflow and supraglottic pressure are shown during the transition from flow-limited breathing with TNI off, to non–flow-limited breathing with TNI at 20 L/minute. Psg = supraglottic catheter pressure (cm H₂O). Numbers in circles: 1, increase in end-expiratory Psg; 2, increase in mean inspiratory airflow; 3, decrease in supraglottic pressure swings on a breath-by-breath basis; 4, Psg threshold for inspiratory flow limitation; and 5, a round, non–flow-limited inspiratory pattern.