The effect of tidal volumes on the time to wean persons with high tetraplegia from ventilators

Study design: Retrospective review of patient medical records comparing the outcomes of two groups of individuals with high-level (C3-4) tetraplegia-t hose with high-volume and those with low-volume mechanical ventilation. Objectives: To determine if higher volume mechanical ventilation contribute s to faster weaning from the ventilator with fewer complications in individ uals with ventilator dependent high-level tetraplegia. Setting: A Model Spinal Injury Center, located in Colorado, USA, which trea ts patients referred from throughout the Rocky Mountain region as well as o ther states. Methods: The medical records of 42 individuals with ventilator dependent C3 -4 tetraplegia, admitted consecutively to the Rocky Mountain Regional Spina l Injury System between 1983 and 1993, were reviewed. All had required full -time mechanical ventilation upon admission, but had successfully weaned by discharge. They were divided into two groups that differed with respect to the ventilator tidal volumes used during their treatment and weaning: a la rge volume group (>20 mls/kg of body weight) and a smaller volume group (<2 0 mls/kg of body weight). Results: Though the two groups were equivalent in neurological level and co mpleteness, muscular function, initial spontaneous vital capacity, the wean ing method used (T-piece), and final spontaneous vital capacity, those in t he large tidal volume group successfully weaned an average of 21 days faste r than the lower tidal volume group (37.6 days vs 58.7 days, P=0.02). They also had significantly less atelectasis (P=0.01) than the lower tidal volum e group. Conclusion: This research suggests that the use of higher ventilator tidal volumes may speed up the weaning process and lessen respiratory complicatio ns. Because of the potential for this to decrease the length and cost of th e rehabilitation programs for persons with high-level tetraplegia, further large-scale research is needed to verify these single-center findings.