[First experience of using adaptive support ventilation (ASV) mode in patients with severe traumatic brain injury]

Capabilities and limitations of ASV mode in TBI patients are studied. 12 patients with severe TBI were enrolled in the study. ICP, MAP, CPP were monitored in all the patients. Cerebral regional blood flow was monitored by thermal diffusion in four patients. Hamilton G5 ventilator was used for mechanical ventilation and respiratory monitoring in all cases. Starting mode of mechanical ventilation was ASV with 100% mechanical substitution. The patient was regarded as ASV-nonresponder and switched to another mode when normoventilation was not possible with any percent of respiratory substitution. ASV mode provided normoventilation during all period of mechanical ventilation in 88 ou of 12 patients. In 4 out of 12 patients ASV mode led to hyperventilation with EtC02 decrease, cerebral regional blood flow slowing and P0,1 index increase. In three patients hyperventilation was induced by high rate of spontaneous breaths caused by brainstem irritation. Switching these patients to SIMV-VC led to normoventilation, normalization of etC02 and cerebral regional blood flow, and P0,1 index decrease. In one patient hyperventilation was caused by lung mechanics disorder when ventilator tried to achieve target minute volume by low tidal volume and high respiratory rate. ASV mode provides adequate lung ventilation during respiratory support period in most patients with severe TBI. It can prove ineffective for some patients with brainstem irritation or lung mechanics disorders.