Longitudinal analysis of inspiratory support requirements in obesity hypoventilation syndrome: is NIV de-escalation...

Optimal long-term management and inspiratory support requirements remain debated in obesity hypoventilation syndrome (OHS).

This prospective, observational study assessed inspiratory support requirements in OHS patients initiating noninvasive ventilation (NIV) after acute hypercapnic respiratory failure, using a volume-assured mode targeting normocapnia.

Ventilator data and clinical parameters were collected at baseline, 1 month, 3 months, 6 months and 12 months after initiation of NIV. Inspiratory support requirements were assessed using driving pressure and apparent respiratory system compliance and compared over time using the Wilcoxon test and Friedman analysis of variance. Groups with persistent and minimal inspiratory support needs at 1 year were compared using Mann-Whitney, χ² and Cochran Q tests.

Of 40 enrolled patients, 39 completed the study. Therapeutic adherence (37 (94.9%)) and efficacy (35 (89.7%)) were high. Inspiratory support requirements decreased over the study period (12.1 (9.6-14.9) to 9.9 (6.3-12.2) cmH₂O, p<0.001), though 84.6% of patients still required >5 cmH₂O driving pressure. Initial driving pressure, higher minute ventilation and higher apparent respiratory system compliance were associated with reduced support requirements after 1 year, but no baseline parameter reliably predicted minimal support need. Reduced ventilatory support at 6 months demonstrated the strongest correlation with maintaining lower driving pressure at 12 months.

Inspiratory support needs reduce over 12 months in OHS patients acutely initiated on long-term NIV, but few patients showed only minimal inspiratory support requirements to maintain normocapnia. Reliable reduction was apparent after 6 months of treatment, suggesting that respiratory muscle recovery is slower than previously assumed. Further studies are needed to verify whether an initial 'hit hard' approach with sequential de-escalation of ventilatory support results in optimal outcome.