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

Killen Harold Briones Claudett123*, Monica Briones Claudett4, Miguel Chung Sang Wong5, Alberto Nuques Martinez6, Ricardo Soto Espinoza6, Mayra Montalvo7, Antonio Esquinas Rodriguez8, Gumersindo Gonzalez Diaz8 and Michelle Grunauer Andrade7

Author Affiliations

1 Pulmonology Department, Military Hospital, Guayaquil, Ecuador

2 Department of Respiratory Medicine, Panamericana Clinic, Guayaquil, Ecuador

3 Department of Respiratory Medicine – Intensive Care, Santa Maria Clinic, Guayaquil, Ecuador

4 Department of Pneumology – Intensive Care, Regional Hospital of Guayaquil, Guayaquil, Ecuador

5 Intensive Care Medicine, Santa Maria Clinic, Military Hospital, Guayaquil, Ecuador

6 Intensive Care Medicine Panamericana Clinic and Ecuadorian Institute Social Security (IESS), Guayaquil, Ecuador

7 Universidad San Francisco de Quito, Quito, Ecuador

8 Intensive Care Unit and Pneumology Services of the Hospital JM Morales Meseguer, Murcia, Spain

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BMC Pulmonary Medicine 2013, 13:12  doi:10.1186/1471-2466-13-12

Published: 12 March 2013



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.


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.


We observed statistically significant differences in favor of the BiPAP S/T + AVAPS group in GCS (P = .00001), pCO2 (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.


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

BiPAP S/T with AVAPS; BiPAP S/T (spontaneous/time); Hypercapnic encephalopathy; Chronic obstructive pulmonary disease