Noninvasive mechanical ventilation with average volume assured pressure support (AVAPS) in patients with chronic obstructive pulmonary disease and hypercapnic encephalopathy.

BACKGROUND: Non-invasive mechanical ventilation (NIV) in patients with acute respiratory failure has been traditionally determined based on clinical assessment and changes in blood gases, with NIV support pressures manually adjusted by an operator. Bilevel positive airway pressure-spontaneous/timed (BiPAP S/T) with average volume assured pressure support (AVAPS) uses a fixed tidal volume that automatically adjusts to a patient's needs. Our study assessed the use of BiPAP S/T with AVAPS in patients with chronic obstructive pulmonary disease (COPD) and hypercapnic encephalopathy as compared to BiPAP S/T alone, upon immediate arrival in the Emergency-ICU. METHODS: We carried out a prospective interventional match-controlled study in Guayaquil, Ecuador. A total of 22 patients were analyzed. Eleven with COPD exacerbations and hypercapnic encephalopathy with a Glasgow Coma Scale (GCS) <10 and a pH of 7.25-7.35 were assigned to receive NIV via BiPAP S/T with AVAPS. Eleven patients were selected as paired controls for the initial group by physicians who were unfamiliar with our study, and these patients were administered BiPAP S/T. Arterial blood gases, GCS, vital signs, and ventilatory parameters were then measured and compared between the two groups. RESULTS: We observed statistically significant differences in favor of the BiPAP S/T + AVAPS group in GCS (P = .00001), pCO(2) (P = .03) and maximum inspiratory positive airway pressure (IPAP) (P = .005), among others. However, no significant differences in terms of length of stay or days on NIV were observed. CONCLUSIONS: BiPAP S/T with AVAPS facilitates rapid recovery of consciousness when compared to traditional BiPAP S/T in patients with chronic obstructive pulmonary disease and hypercapnic encephalopathy. TRIAL REGISTRATION: Current Controlled Trials application ref is ISRCTN05135218.

Noninvasive mechanical ventilation in patients with chronic obstructive pulmonary disease and severe hypercapnic neurological deterioration in the emergency room.

OBJECTIVES: The objective of this study was to assess the effectiveness of noninvasive motion ventilation (NIMV) in patients with chronic obstructive pulmonary disease (COPD), having infectious exacerbation and severe hypercapnic neurological dysfunction in the emergency room. DESIGN: This is a prospective interventional study. SETTING: The study setting was the emergency room at the Military Hospital in Guayaquil, Ecuador. PATIENTS: A total of 24 patients were studied. Twelve patients had acute exacerbation of their chronic obstructive pulmonary disease: they presented at the emergency room with severe neurological dysfunction, with a Glasgow Coma Scale (GCS) score of less than 8 and a pH of less than 7.25. These patients were compared with 12 controls who were being treated with invasive mechanical ventilation (IMV), who were then matched according to their GCS scores, pH status, Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, and age. INTERVENTIONS: We evaluated the effectiveness and safety of applying a ventilatory strategy based on a biphasic positive airway pressure protocol in the emergency room. MEASUREMENTS AND RESULTS: The pH, PCO2, and GCS scores, measured during the first 3 h, were predictors of success for the application of NIMV treatment (P<0.05). Mortality was 33.3 and 16.7% for the IMV and the NIMV groups, respectively (P=0.01). Days of IMV were 5.60+/-1.2 versus 3.6+/-1.1 for NIMV (P=0.006). Days of hospitalization were 11.1+/-4.7 for the IMV group and 6.5+/-1.9 for the NIMV group (P=0.001). The cumulative survival rates at 6 months were 71.4 and 80% for the IMV and NIMV groups, respectively (P=0.80). CONCLUSION: We consider that severe neurological dysfunction and pH of less than 7.25 do not constitute absolute contraindications to the use of NIMV. This kind of management can be implemented in the emergency room with favorable results.