Apnea-Hypopnea Index in Chronic Obstructive Pulmonary Disease Exacerbation Requiring Noninvasive Mechanical Ventilation with Average Volume-Assured Pressure Support.

INTRODUCTION: This study intends to determine the Apnea-Hypopnea Index in patients hospitalized with acute hypercapnic respiratory failure from chronic obstructive pulmonary disease exacerbation, who require noninvasive ventilation with average volume-assured pressure support (AVAPS), as well as describes the clinical characteristics of these patients. MATERIALS AND METHODS: We designed a single-center prospective study. The coexistence of Apnea-Hypopnea Index and clinical, gasometric, spirometric, respiratory polygraphy, and ventilatory characteristics were determined. The clinical characteristics found were categorized and compared according to the Apnea-Hypopnea Index (AHI) < 5, AHI 5-15, and AHI >15. A p value <0.05 was considered statistically significant. RESULTS: During the study period, a total of 100 patients were admitted to the ICU with a diagnosis of acute hypercapnic respiratory failure due to COPD exacerbation. 72 patients presented with acute respiratory failure and fulfilled criteria for ventilatory support. Within them, 24 received invasive mechanical ventilation and 48 NIV. After applying the inclusion criteria for this study, 30 patients were eligible. An AHI >5 was present in 24 of the 30 patients recruited (80%). Neck circumference (cm), Epworth scale, and Mallampati score evidenced significant differences when compared to the patient's AHI <5, AHI 5-15, and AHI >15 (p < 0.05). Furthermore, patients with an AHI >5 had longer hospital admissions, prolonged periods on mechanical ventilation, and a higher percentage of intubation rates. CONCLUSION: Apnea-Hypopnea Index and chronic obstructive pulmonary disease exacerbation are a frequent association found in patients with acute hypercapnic respiratory failure and COPD exacerbations that require NIV. This association could be a determining factor in the response to NIV, especially when AVAPS is used as a ventilatory strategy.

Non-invasive mechanical ventilation with average volume-assured pressure support. Results according to the aetiology of acute respiratory failure.

INTRODUCTION: Until now, the ventilatory strategy with BiPAP S/T plus average volume-assured pressure support (AVAPS) has not been evaluated for its use in the different types of acute respiratory failure (ARF). Consequently we report the results of the use of this ventilatory strategy in these clinical scenarios. MATERIAL AND METHODS: This is a single-centre prospective study. The subjects were categorised according to the type of ARF: (1) hypercapnic ARF: chronic obstructive pulmonary disease and bronchial asthma; and (2) hypoxaemic ARF: pneumonia, acute respiratory distress syndrome, congestive heart failure, and interstitial lung disease. Multiple logistic regression was used to determine predictors of non-invasive mechanical ventilation (NIV) failure (intubation). Further, in a subgroup of patients with de novo hypoxaemic ARF, analysis of variances with repeated measures was used to determine factors associated with NIV outcome. RESULTS: Sixty-eight subjects were included in this study. The NIV success rate was 69.1% and the mortality rate was 20.6%. A multivariate analysis showed that the number of affected lung quadrants on chest X-ray (OR: 4.23, 95% CI: 4.17-4.31; P < 0.001) and ARF precipitating disease (OR: 4.46, 95% CI: 4.43-4.51; P < 0.001) were determinants of NIV failure. In the hypoxaemic ARF subgroup (n = 58), significant differences in several parameters were found between patients with positive and negative outcomes. CONCLUSIONS: The use of BiPAP S/T - AVAPS in subjects with hypercapnic ARF is associated with a better outcome than in those with de novo hypoxaemic ARF.

Use of noninvasive mechanical ventilation with pressure support guaranteed with average volume in de novo hypoxaemic respiratory failure. A pilot study.

BACKGROUND: This study was designed to determine the results associated with the use of noninvasive mechanical ventilation (NIV) using the BiPAP S/T-AVAPS ventilation strategy in subjects with mild to moderate de novohypoxaemicrespiratory failure. METHODS: This is a prospective study that includes subjects with de novohypoxaemic respiratory failure (not produced by acute exacerbations of COPD, chronic lung disease, or congestive heart failure) with mild to moderate PaO2/FiO2, who were admitted to the Intensive Care Unit (ICU) of Santa Maria Clinic in Guayaquil, Ecuador. Subjects were divided into two groups and compared according to their PaO2/FiO2: higher than 100 and up to 200 mm Hg (moderate ARDS) or between 200 and 300 mm Hg (mild ARDS) (both groups were ventilated with the BiPAP S/T-AVAPS strategy). A value of P < 0.05 was considered significant. RESULTS: A total of 38 subjects were analysed in this study. The total rate of intubation was 34.2% while the mortality rate was 28.9%. Significant differences were observed when comparing success versus failure in exhaled tidal volumes (P = 0.04), peak inspired pressure (P < 0.001), PaO2 (P < 0.001), SaO2 (P < 0.002), PaO2/FiO2 (P < 0.002), RR (P < 0.001), HR (P < 0.001), and inspiratory time (P = 0.029) measured at baseline and at 12-hour, 24-hour and 48-hour intervals. CONCLUSION: The BiPAP S/T-AVAPS ventilatory mode can be used in subjects with de novo hypoxaemic respiratory failure with special vigilance concerning exhaled tidal volumes and inspired pressure.