Intermittent Negative Pressure Ventilation (INPV) during anaesthesia for Laser Therapy (LT) of endo-bronchial lesions

Purpose: The aim of this study was to evaluate changes in breathing pattern and blood gases during anaesthesia with and without INPV for LT. Methods: 27 consecutive patients (mean age 60±4 years) underwent LT under general anesthesia (opioides and propofol infusion) still maintaining a residual respiratory activity at a FIO2 able to obtain a SatO2> 95%. 13 out of 27 patients performed INPV by a poncho-wrap with the following setting (negative pressure 25-30 cmH2O; respiratory rate RR 10-15 acts/min). 14 matched patients (Controls) performed the procedure without INPV. Arterial blood gases were evaluated baseline and after 30 minutes since anaesthetic induction. RR, tidal volume (VT), apnoea-hyponea index (AHI) and apnoea/hyponea duration (AHD), SatO2 and heart rate (HR) were continuously recorded. Number of manual ventilation necessity (Noventil) was also recorded. Results: The table shows differences between groups under anesthesia for LT. INPV p< Controls No 13 14 pH 7.35±0.08 .001 7.25±0.04 PaCO2 mmHg 47±10 .001 66±10 PaO2 mmHg 94±27 ns 126±93 O2 supply L/m 2.5±3 .005 15±4 SatO2 95±3 ns 97±3 RR act/m 13±3 ns 11±5 VTmean (% baseline) 243±125 .0005 80±28 AH Index (event/h) 16±7 .005 62±37 AH Duration (% time) 14±12 .05 50±21 HR b/m 86±14 .05 101±13 No Ventil. 0.5±0.7 .05 3±3 Conclusions: The use of INFV during anaesthesia for LT is associated to less severe levels of acidosis, to a reduction in anaesthesia induced apnoeas. Clinical implications: INVP may be proposed as an useful aid in this procedure. Further studies would demonstrate its utility in pharmacologically paralized patients.