Effects of Modes, Obesity, and Body Position on Non- invasive Positive Pressure Ventilation Success in the Intensive Care Unit: A Randomized Controlled Study

Özet

OBJECTIVES: Different outcomes and success rates of non-invasive positive pressure ventilation (NPPV) in patients with acute hypercapnicrespiratory failure (AHRF) still pose a significant problem in intensive care units. Previous studies investigating different modes, body posi-tioning, and obesity-associated hypoventilation in patients with chronic respiratory failure showed that these factors may affect ventilatormechanics to achieve a better minute ventilation. This study tried to compare pressure support (BiPAP-S) and average volume targetedpressure support (AVAPS-S) modes in patients with acute or acute-on-chronic hypercapnic respiratory failure. In addition, short-term effectsof body position and obesity within both modes were analyzed.MATERIAL and METHODS: We conducted a randomized controlled study in a 7-bed intensive care unit. The course of blood gas analysisand differences in ventilation variables were compared between BiPAP-S (n=33) and AVAPS-S (n=29), and between semi-recumbent andlateral positions in both modes.RESULTS: No difference was found in the length of hospital stay and the course of PaCO2, pH, and HCO3 levels between the modes.There was a mean reduction of 5.7±4.1 mmHg in the PaCO2 levels in the AVAPS-S mode, and 2.7±2.3 mmHg in the BiPAP-S modeper session (p<0.05). Obesity didn't have any effect on the course of PaCO2 in both the modes. Body positioning had no notable effectin both modes.CONCLUSION: Although the decrease in the PaCO2 levels in the AVAPS-S mode per session was remarkably high, the course was similarin both modes. Furthermore, obesity and body positioning had no prominent effect on the PaCO2 response and ventilator mechanics. Posthoc power analysis showed that the sample size was not adequate to detect a significant difference between the modes.