Effects of different positions of the patients mechanically ventilated under general anesthesia on respiratory mechanics during one or both lung ventilation before thoracotomy / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effects of different positions of the patients mechanically ventilated under general anesthesia on respiratory mechanics during one or both lung ventilation before thoracotomy.Methods Twelve ASA Ⅰ or Ⅱ patients of both sexes (8 males, 4 females) aged 33-63 years weighing 62-85 kg scheduled for general thoracic surgery were studied. The preoperative lung function of the patients was normal. The patients were premedicated with intramuscular pethidine, promethazine and atropine. Anesthesia was induced with fentanyl, droperidol, midazolam, propofol and vecuronium. Left-sided double-lumen tube was inserted and correct placement was confirmed using a fiberoptic bronchoscope inserted through the bronchial lumen. Anesthesia was maintained with propofol and vecuronium infusion. The magnitude of neuro-muscular blockade was monitored by stimulation of radial nerve with TOF pulses. T4/T1 was maintained at 0 during study. The patients were placed in supine, left and right lateral position. In each position both lungs, left and right lung were ventilated for 10 min respectively. The non-ventilated bronchial lumen was open to the air during one-lung ventilation. The ventilatory parameters were kept unchanged during the study (VT = 8-10 ml?kg-1 , RR = 12 bpm, IE = 12). Pressure-volume loop (P-V loop), peak airway pressure (Ppeak), airway resistance (Raw), total compliance (CT) (lung and thorax) and PETCO2 were measured and recorded at the end of each 10 min ventilation using S/5 monitor ( Datex-Ohmeda Finland) . Results During both lung ventilation Ppeak was significantly increased and CT was significantly decreased in left and right lateral position as compared with supine position ( P