Noninvasive mechanical ventilation with BiPAP therapy for comatose exacerbation of chronic obstructive pulmonary disease through an endotracheal tube: is it justified?

We read with interest the paper by Rawat et al1 related to the role of bilevel positive airway pressure (BiPAP) delivered via endotracheal tube in unconscious patients suffering from acute exacerbations of chronic obstructive pulmonary disease in a real-world situation. Although the authors provide some justification for the use of BiPAP through an endotracheal tube, we believe that this technique is fraught with complications and should not be routinely employed. In fact, three patients failed BiPAP therapy, two patients received conventional invasive ventilation, and one patient failed to respond to BiPAP. Thus, almost 30% of patients either failed or showed no evidence for benefit of BiPAP. Further, the authors provide no data on the amount of leakage that was present while administering BiPAP therapy. The authors also do not provide details on whether the nurses/chest therapist administered intermittent manual bag ventilation. Ideally, the authors should have referred the patients on manual bag ventilation to another public health center where facilities for invasive ventilation are available free of cost. From a physiological standpoint, assist-control mode is preferred in patients with severe acidosis and exacerbation of chronic obstructive pulmonary disease. The BiPAP mode has advantages only with an intact drive (not apnea). Thus, in patients with a decreased level of consciousness or apnea, we may suppose that the assist-control mode is more effective for achieving effective muscular rest and ventilation, as shown by Nava et al.2 Application of high positive pressures alone does not guarantee an adequate tidal volume.3 Moreover, there is no definite relationship between high pressure levels and adequate washout of pCO2. Finally, the authors provide no explanation regarding the failure of therapy in nonresponders, but believe that the device delivered an adequate amount of positive pressure. In summary, although this study provides evidence for a new treatment strategy in patients with a low level of consciousness, we believe that this should only be considered after appropriate assessment of the risks and benefits of this practice and further evidence from animal/experimental models that such equipment is safe and efficacious.