Reply to Letter to Editor Concerning “Nocturnal Pressure Controlled Ventilation Improves Sleep Efficiency in Patients Receiving Mechanical Ventilation”

Dear Editor,

Thank you for forwarding the reader’s letter regarding our recent publication in Respiratory Care. We appreciate the opportunity to address the concerns raised.

First, we acknowledge the reader’s insightful critique regarding the complexities of managing nocturnal ventilatory support and the challenges faced by health care professionals in optimizing patient care. Achieving a balance between ventilatory support and minimizing sleep disruption is indeed crucial. However, there are several points we would like to clarify.

Regarding the comment on pressure controlled ventilation (PCV) and its purported benefits for ventilatory muscle rest and successful weaning, we respectfully maintain our conclusion based on the reviewed literature.^1,2 Whereas we acknowledge the lack of unanimous consensus on this topic, several studies referenced in our meta-analysis suggest potential advantages of PCV in specific patient populations.^1-5 We emphasize that our analysis aims to consolidate existing evidence rather than propose definitive conclusions for all clinical scenarios.

Regarding the methodological concerns raised, particularly regarding heterogeneity issues, we performed a subgroup analysis to manage these challenges. Initially, Fajardo-Campoverdi expressed concern regarding the heterogeneity index (I²) of 70.5% (P = .07) for the primary outcome. However, following the subgroup analysis, the I² was reduced accordingly. This reduction suggests that factors such as different ventilator-dependent statuses or levels of pressure support may have contributed significantly to the observed heterogeneity. Regarding the suggested consideration of the 30% difference in pressure support levels between groups, we maintain that the primary goal of PCV is to optimize patient rest. Therefore, the absolute level of pressure control may not necessarily correlate directly with outcomes if patient comfort and respiratory effort reduction are achieved. Additionally, we accounted for varying pressure support levels across studies and presented detailed subgroup analysis in figures of our manuscript, as discussed in the fourth paragraph of our Discussion section.

Addressing the critique of nonsignificant outcomes in specific trials (eg, Toublanc’s and Cabello’s studies),^5,6 we attribute these findings partly to the sample sizes of the included trials.^3-6 Despite our rigorous screening process to include studies meeting predefined eligibility criteria, our analysis was limited to 4 small crossover trials. Nevertheless, all data were transparently reported, and full results are accessible in our manuscript figures. Our meta-analysis adhered to conventional methods appropriate for pooling available data, and our methodology, including data synthesis techniques, is also registered and available on PROSPERO under registration number CRD42023410731.

Whereas Bayesian approaches offer valuable insights, data derived from proportional assist ventilation (PAV)^7,8 or neutrally adjusted ventilatory assist (NAVA)⁹ should be excluded at this time because the feature among NAVA, PAV and PCV is quite different. Furthermore, although Fajardo-Campoverdi claimed that they found the association between PEEP, total sleep time, and sleep efficiency, however, total sleep time was confounded by the recording time selected by the neurophysiologist. Take Cabello’s trial as an example, half the total sleep time occurred during daytime, but the recording time was arranged in the nighttime with three 6-h periods.⁶ Nonetheless, we agree that PEEP may play a role in improving sleep efficiency in patients with chronic lung disease or chronic heart failure because it may alleviate air trapping or reduce the cardiac afterload. We also agree that careful consideration of ventilatory support levels is essential to avoid excessive pressure.

In conclusion, we appreciate the reader’s engagement with our work and the opportunity to clarify our methodology and findings. We remain committed to advancing understanding in this challenging area of respiratory care and look forward to future studies that may build upon our findings.

Thank you once again for facilitating this discussion.