Effects of individualized ventilation on the respiratory mechanics and oxygenation in elderly patients during the recovery period after lobectomy

Abstract

Objective To discuss the effects of individualized setting of positive end-expiratory pressure (PEEP) based on electrical impedance tomography (EIT) on the respiratory mechanics and oxygenation in elderly patients during the recovery period after lobectomy. Methods Eighty-two elderly patients who were scheduled for thoracoscopic lobectomy were divided into two groups (n=41), according to the random number table method: a control group and an individualized PEEP group. After surgery, synchronized intermittent mandatory ventilation was adopted in the postanesthesia care unit (PACU), with a tidal volume of 8 ml/kg. The PEEP value of the control group was set at 5 cmH2O (1 cmH2O=0.098 kPa). The PEEP value of the individualized PEEP group was determined based on EIT; the optimal PEEP value was considered as the crossing of the curves representing lung hyperinflation and collapse in the EIT monitoring chart. The oxygenation index (OI) at the time points of entering into PACU (T1), mechanical ventilation over 0.5 h (T2), and going out of PACU (T3), as well as dynamic respiratory system compliance (Cdyn) and driving pressure (ΔP) at T1 and T2 were recorded for analysis. The primary outcome measures included OI, Cdyn and ΔP. The secondary outcome measures were the peak airway pressure (Ppeak), mean airway pressure (Pmean), mean arterial pressure (MAP), the use of vasoactive agents, pH, PaCO2, the incidence of hypoxia, extubation time and the length of stay in PACU. Results The EIT-titrated PEEP (with a median of 9 cmH2O) was significantly higher than that of the control group. Compared with the control group, the individualized PEEP group had increased OI and Cdyn and decreased ΔP at T2 (P 0.05). Conclusions Individualized PEEP setting in elderly patients after lobectomy can effectively improve OI, reduce ΔP and improve Cdyn in the recovery period, without significant effects on extubation time, the incidence of hypoxia and the length of stay in PACU. Key words: Pulmonary lobectomy; Lung protective ventilation; Positive end-expiratory pressure; Electrical impedance tomography