Effects of different ventilation strategies on exhaled nitric oxide in geriatric abdominal surgery

Exhaled nitric oxide (eNO) has been suggested to be a marker of small airway injury. We investigated the effects of different ventilation strategies on eNO. Sixty-nine patients who received elective open abdominal surgery under general anesthesia with more than 2 h of surgery duration were randomly divided into three groups: high tidal volume of 10-12 ml kg(-1) predicted body weight (PBW) with zero end-expiratory pressure (ZEEP) (high VT + ZEEP group); low tidal volume of 6-8 ml kg(-1) PBW with 8 cm H2O positive end-expiratory pressure (PEEP) (low VT + PEEP group); and low tidal volume of 6-8 ml kg(-1) PBW with 8 cm H2O PEEP and recruitment maneuvers (low VT + PEEP + RMs group). eNO, respiratory system compliance (Crs), oxygenation index, inflammatory mediators tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-1β), IL-8, prostaglandin E2 (PGE2) and PGF2a as well as pulmonary function were measured during the perioperative period. The postoperative eNO decreased in 78.3% of patients in the high VT + ZEEP group and low VT + PEEP group, and increased in 56.5% of patients in the low VT + PEEP + RMs group (P = 0.016). The Crs level in the high VT + ZEEP group significantly decreased with time but significantly increased in the low VT + PEEP + RMs group (P < 0.05). The oxygenation index, inflammatory mediators and pulmonary function did not statistically differ among the three groups. Compared with the low VT + PEEP + RMs group, the decreasing rate of postoperative eNO in the high VT + ZEEP and low VT + PEEP groups was higher, which may imply small airway injury during geriatric abdominal surgery.