Abstract No.: ABS0586: Is pressure control ventilation better than volume control in patients undergoing spine surgery in prone position?

BACKGROUND & AIMS: Optimisation of intraoperative ventilation is feasible nowadays due to availability of several new modes in anaesthesia workstations. Spine surgery in prone position leads to pulmonary and haemodynamic alterations. The present study aimed to compare PCV and VCV modes of ventilation in patients undergoing spine surgeries. METHODS: After obtaining approval from institutional ethics committee the present, prospective, randomised study was conducted in 50 adult patient of either sex, ASA I or II undergoing thoracic or lumbar spine surgery in prone position. Standard anaesthesia protocols using Thiopentone, Fentanyl and Vecuroniun was followed. Patients in VCV group (n=25) were ventilated with volume control mode with TV = 7 ml/kg, PEEP=5cm H2O, I: E=1:2 and respiratory rate adjusted to keep Et CO2 between 35-40 mmHg and FiO2 =0.4. While in PCV mode (n=25) patients were ventilated with similar settings except PIP was adjusted to determine TV=7ml/kg. Draeger Primus workstation was used. RESULTS: Demographic profile, duration of surgery, intraoperative dry and fluid consumption were comparable in two groups. Peak inspiratory pressure was higher in VCV (20 vs 18) and dynamics compliance was low in VCV (31.3 vs 35.93). Minute ventilation, EtCO2, dead space, O2 saturation was comparable in two groups though alveolar oxygenation was better in PCV. Diastolicblood pressure was low in VCV. Postoperative PFT decreased in both groups but were comparable. CONCLUSION: PCV is better than VCV in maintaining intraoperative respiratory mechanisms but whether they offer long term benefit require more studies comprising of larger sample sizes.