medwireNews: The need for endotracheal intubation in patients with chronic obstructive pulmonary disease (COPD) and persistent hypercapnia can be significantly reduced using high- rather than low-intensity noninvasive positive pressure ventilation (NPPV), Chinese research suggests.
The HAPPEN randomized controlled trial involved 300 patients with an acute exacerbation of COPD who had a partial pressure of carbon dioxide (PaC02) level greater than 45 mmHg (mean 79 mmHg) after receiving 6 hours of low-intensity NPPV.
The participants (mean age 73 years; 68% men) were selected from the respiratory, nonintensive care wards of 30 Chinese hospitals between January 2019 and January 2022.
They were assigned to receive high-intensity NPPV, with inspiratory positive airway pressure adjusted to give a tidal volume of 10–15 mL/kg of predicted bodyweight, or to continue with low-intensity NPPV, with inspiratory positive airway pressure adjusted to obtain a tidal volume of 6–10 mL/kg of predicted bodyweight. In both groups, the target respiratory rate was 25 breaths/minute.
Endotracheal intubation during hospitalization was considered necessary if a patient had an arterial pH level below 7.25 with a PaC02 increase from baseline of more than 20% or a ratio of PaC02 to fraction of inspired oxygen of less than 100 mmHg, and at least one critical clinical sign, such as coma, severe hemodynamic instability, or excessive respiratory secretions, aspirations, or vomiting.
The need for endotracheal intubation during hospitalization was more than halved for patients in the high-intensity NPPV group, compared with the low-intensity NPPV group, at seven (4.8%) of 147 patients versus 21 (13.7%) of 153 patients, giving a significant 8.9 percentage point difference.
But researcher Zhixin Cao (Beijing Chao-Yang Hospital, China) and colleagues note in JAMA that there was no significant difference in the actual rates of endotracheal intubation between the high- and low-intensity NPPV groups, at a respective 3.4% and 3.9%. This was primarily due to patients given low-intensity NPPV being able to crossover to high-intensity NPPV if they met the criteria for endotracheal intubation, which was the case for 13 (61.9%) of the 21 affected individuals.
Of these 13 individuals, 15.4% were intubated and 84.6% were not, and therefore the composite outcome of endotracheal intubation or avoiding endotracheal intubation by crossing over to high-intensity NPPV was significantly lower in the high-intensity than the low-intensity NPPV arm, at 3.4% versus 11.1%.
In a related editorial, Wolfram Windisch (Witten/Herdecke University, Cologne, Germany) and associates say that a “critique” of the trial might be that the “predefined criteria for the need for intubation did not translate to actual intubation rates, because not all patients who met these prespecified criteria were eventually intubated.“
They therefore state that the “true clinical effect of high-intensity NPPV may be less than that reflected by the between-group difference for the primary outcome of need for intubation.”
Windisch et al say that the results “cannot be assumed to apply to patients with more severe respiratory distress, particularly those who are likely to develop dynamic hyperinflation. Nevertheless, this study clearly broadens the view of potential treatment strategies in patients with an exacerbation of COPD and respiratory acidosis.”
In terms of safety outcomes, rates of abdominal distension were higher in the high-intensity than the low-intensity NPPV group (37.4 vs 25.5%), but no patients requested removal of NPPV due to abdominal distension, the investigators report.
Severe alkalosis rates were “mildly” higher with high-intensity than low-intensity NPPV (4.1 vs 0.0%), otherwise “severe adverse events were rare and similar between groups,” says the team, occurring in 5.4% and 5.9%, respectively.
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JAMA 2024; doi:10.1001/jama.2024.15815
JAMA 2024; doi:10.1001/jama.2024.0811
