Breathing Pattern andArterial Blood GasesDuring Nd-YAGLaser Photoresection ofEndobronchial Lesions UnderGeneral Anesthesia* UseofNegative Pressure Ventilation: APreliminary Study

Study objective: Toevaluate theefficacy ofnegative pressure ventilation (NPV) inavoiding or reducing apneas andrelated hypoxemia andrespiratory acidosis during lasertherapy (LT) of endobronchial lesions. Design: Aprospective, controlled, randomized study. Setting: Anoperating theater ofarespiratory endoscopy andlaser therapy unit. Population andintervention: Twenty-seven consecutive patients referred toLTwere entered intothe study. Fourteen patients were randomly assigned toLTundergeneral anesthesia andspontaneous assisted ventilation (control group) whereas in13cases, NPVby a poncho-wrap ventilator (NPV group) was added totheprocedure. Measurements andresults: Theprevalence andtheduration ofapnea/hypopnea periods assessed by respiratory inductive plethysmography during LT were significantly reduced underNPV,compared tothecontrol group. Ascompared tobaseline, during LT,allcontrol patients developed mild to severehypercapnia (PaC02 ranging from55to76mm Hg) andrespiratory acidosis (pH from7.33 to 7.19), whereas only three patients undergoing NPV(23%) developed hypercapnia (PaC02 from52to 68mm Hg) andrelated acidosis (pH from7.29 to7.21). Optimal oxygenation was achieved inall ofthe patients; nevertheless, patients under NPVneeded a lower mean oxygen supply; five ofthem(38%) could betreated ata fraction ofinspired oxygen of0.21forthewholeprocedure. Conclusion: NPVmaybeuseful inreducing apneasduring laser therapy undergeneral anesthesia, thusreducing hypercapnia, related acidosis, andneedofoxygen supplementation. (CHEST 1997; 112:1466-73)