Predictors of Noninvasive Ventilation Failure in Critically Ill Obese Patients: A Brief Narrative Review

Abstract

Non-invasive ventilation ( NIV ) has been used successfully for the management of acute respiratory failure (ARF) more often in the last two decades than previously. Unfortunately, NIV can have failure rates ranging from 5% to 50% and patient selection is the key to success. There are particular groups of patients that are more likely to benefit from NIV. For patients with hypoventilation syndrome (OHS) this treatment can be beneficial. This review seeks to evaluate the effectiveness of NIV in acute ARF and determine predictors of NIV failure in morbidly obese patients. Only a few studies have investigated NIV success or failure in these patients. NIV was most often effective when patients were carefully selected. Obese patients who exhibited early NIV failure had a high severity score at admission. In contrast, more than half of hypercapnic patients with decompensated OHS exhibited a delayed but successful response to NIV. Patients with decompensation of OHS had better prognosis and response to NIV than other hypercapnic patients. They required more aggressive NIV settings, a longer time to reduce paCO 2 levels, and more frequently a delayed but successful response to NIV which should encourage the use of NIV rather than early intubation. Since clear predictors of NIV failure have not been identified, a strict and prolonged monitoring is mandatory.

Pathophysiology and Management of Acute Respiratory Distress Syndrome in Obese Patients

“…89 The factors associated with treatment failure were pneumonia, sepsis, and higher severity scores at admissions, common features of patients with ARDS. In summary, it has been suggested how noninvasive ventilation may be safely used in patients with hypercapnic acute respiratory decompensation of obesityhypoventilation syndrome, 90 whereas much more caution should be used in the case of acute hypoxemic respiratory failure and ARDS.…”

Acute Respiratory Failure in Obesity-Hypoventilation Syndrome Managed in the ICU

“…36 Higher NIV success rates were found in subjects with acute idiopathic decompensation of OHS and with high P aCO 2 levels. 33,36 Interestingly, subjects with acute-on-chronic respiratory failure had a delayed but successful response to prolonged NIV, which prevented intubation. 33,36 In our study, the median time to correct respiratory acidosis with NIV was 2.9 d, which should encourage the prolonged use of NIV when this is possible, instead of early intubation.…”

“…Studies that evaluated NIV in subjects who were obese and critically ill found NIV failure rates that ranged from 2 to 60%. 23,[32][33][34][35][36] The higher failure rates in these studies than in the current study may be explained by higher severity scores, more severe hypoxemia, and infectious pneumonia as the main reason for acute hypercapnic respiratory failure. 36 Higher NIV success rates were found in subjects with acute idiopathic decompensation of OHS and with high P aCO 2 levels.…”

“…23,[32][33][34][35][36] The higher failure rates in these studies than in the current study may be explained by higher severity scores, more severe hypoxemia, and infectious pneumonia as the main reason for acute hypercapnic respiratory failure. 36 Higher NIV success rates were found in subjects with acute idiopathic decompensation of OHS and with high P aCO 2 levels. 33,36 Interestingly, subjects with acute-on-chronic respiratory failure had a delayed but successful response to prolonged NIV, which prevented intubation.…”

“…33,36 Interestingly, subjects with acute-on-chronic respiratory failure had a delayed but successful response to prolonged NIV, which prevented intubation. 33,36 In our study, the median time to correct respiratory acidosis with NIV was 2.9 d, which should encourage the prolonged use of NIV when this is possible, instead of early intubation. This delay may be explained by the high initial P aCO 2 in our subjects and the reduced neural respiratory drive found in patients with OHS.…”