Can We Extubate Seemingly Unweanable Patients with Neuromuscular Disease?
Abstract & Commentary
By Andrew M. Luks, MD, Pulmonary and Critical Care Medicine, University of Washington, Seattle, is Associate Editor for Critical Care Alert.
Dr. Luks reports no financial relationship to this field of study.
Synopsis: This observational study demonstrated that use of an extubation protocol incorporating non-invasive positive pressure ventilation and mechanically assisted coughing facilitated extubation in neuromuscular disease patients who were unable to pass spontaneous breathing trials.
Source: Bach JR, et al. Extubation of patients with neuromuscular weakness: A new management paradigm. Chest 2010;137:1033-1039.
Patients with neuromuscular disease who are intubated and subsequently fail multiple spontaneous breathing trials are often relegated to placement of a tracheo-stomy and continuous mechanical ventilation. Drawing on success they have had in decannulating unweanable patients with traumatic tetraplegia, Bach and colleagues sought to determine whether a similar protocol involving continuous mechanically assisted coughing (MAC) and non-invasive ventilation (NIV) could be used to extubate neuromuscular disease patients who could not pass spontaneous breathing trials.
The investigators studied the effects of their protocol on a total of 157 patients at two centers. Patients were eligible for participation if they had neuromuscular disease or critical care myopathy, failed spontaneous breathing trials with inspiratory pressure support < 7 cm H2O, had PaCO2 < 40 mm Hg with peak inspiratory pressure < 35 cm H2O on volume assist-control mode, had vital capacity < 20% normal, and maintained SpO2 > 95% for > 12 hours on ambient air. Patients with advanced bulbar amyotrophic lateral sclerosis were excluded due to their high risk of extubation failure.
Patients who met these criteria were extubated directly to NIV on assist-control with a tidal volume of 800-1500 mL delivered via nasal, oral, or mouthpiece interfaces. Assisted cough peak flow (CPF) was measured within 3 hours of extubation. Patients were provided mouthpieces and weaned themselves from NIV by taking intermittent positive pressure ventilation (IPPV) on demand. Patients were also taught to breath-stack with the aid of the ventilator, and when maximally inflated, received abdominal thrusts to help with the cough. Respiratory therapists, nurses, family, and personal attendants also provided MAC via oro-nasal interfaces up to every 20 minutes to maintain SpO2 > 95% and keep the patient free of secretions. Extubation was subsequently considered successful if the patient was discharged without reintubation. If patients required reintubation on multiple occasions, tracheostomy was performed.
Of the 157 patients who participated in the study, 96 had no prior experience with NIV, 20 had been continuously dependent on NIV for 12.2 years prior to intubation, and 41 required part-time ventilation. All extubations performed on patients with assisted CPF > 160 L/min were successful, while 80% of extubations were successful in patients with CPF below this threshold. Six of 8 patients who failed initial extubation attempts succeeded on later attempts and only 2 patients required tracheostomy. Those patients with experience with NIV and MAC prior to intubation were more likely to be successful with extubation. Weaning from full-time to part-time NIV required between 3 and 21 days and often occurred at home. Staff involved in the study reported that treatment with NIV required more time than invasive respiratory care.
Bach and colleagues demonstrate that an intensive program of NIV and MAC can be used to extubate neuromuscular disease patients who are unable to pass traditional spontaneous breathing trials. One would expect significant benefits to accrue from such results, including fewer days of intubation, decreased need for tracheostomy, the ability to return home, and better quality of life. Despite these positive results, this study should not change our extubation practices with neuromuscular disease patients in the ICU. It is important to remember that the protocol used in this study was not implemented in the ICU but, instead, was executed at dedicated ventilator weaning facilities. The time-intensive nature of the protocol (e.g., assisted coughing up to every 20 minutes and extensive family involvement) would likely make such a protocol extremely difficult to execute in the acute care setting. Whether this protocol can be replicated at other centers with less experience in its use is also an open question. As a result, we should not look at this study as a reason to be more aggressive in our extubation of patients with neuromuscular disease in the ICU and should reserve this approach for long-term acute care facilities where the resources demanded by the approach may be more available.
What we may be able to do, however, is change our approach when we are seeing neuromuscular disease patients in acute respiratory failure prior to intubation. Too often such patients are counseled to avoid intubation out of concern that they may never be liberated from the ventilator. Bach and colleagues, however, were able to extubate patients as long as they had a measurable CPF, suggesting that such routine counseling against intubation may not be warranted. Particularly in those patients with prior experience with NIV and MAC and adequate family and caregiver support, intubation may still be a reasonable option, as aggressive post-ICU care in a long-term acute care facility may allow them to be subsequently liberated from the ventilator.