[Effect of positive end-expiratory pressure on cardiac function in patients with early left ventricular diastolic dysfunction: a prospective cohort study].

Objective: To evaluate the effect of positive end-expiratory pressure (PEEP) ventilation on cardiac function in patients with early left ventricular (LV) diastolic dysfunction undergoing laparoscopic radical gastrectomy.

Methods: Patients who underwent laparoscopic radical gastrectomy under elective general anesthesia from July 2021 to February 2022 at the Subei People's Hospital were enrolled [age 60-75 years old, American Society of Anesthesiologists (ASA) grade I-II, and left ventricular ejection fraction (LVEF) > 0.50]. Transthoracic echocardiography (TTE) was performed before operation, and the peak early diastolic velocity (E peak) and peak late diastolic velocity (A peak) at the mitral ostium were recorded and the E/A and E peak deceleration time (DT) were calculated. Then isovolumic relaxation time (IVRT) and early peak mitral annular diastolic velocity (e') were recorded and left ventricular E/e' (LVE/e') was calculated. According to the E/A, mitral e', LVE/e', DT, and IVRT, the patients were divided into early LV diastolic dysfunction group (E/A < 1, mitral e' < 7 cm/s, LVE/e' > 14, DT > 200 ms, and IVRT > 100 ms) and normal cardiac function group (1 < E/A < 2, 160 ms < DT < 240 ms, and 70 ms < IVRT < 90 ms), with 35 patients in each group. Both groups were received fixed 5 cmHO (1 cmHO ≈ 0.098 kPa) PEEP 5 minutes after the beginning of the pneumoperitoneum until the end of the procedure. A volume controlled ventilation was used with a tidal volume (VT) of 7 mL/kg, an inspired oxygen concentration of 0.60, and an inspiratory to expiratory ratio of 1:2. Left and right myocardial systolic and diastolic function related parameters, including LVEF, LV global longitudinal strain (LVGLS), tricuspid annulus plane systolic migration (TAPSE), the peak early diastolic velocity (E peak) at the mitral and tricuspid valve ostia and the peak early diastolic velocity (e') at the corresponding annulus were measured by transesophageal echocardiography (TEE) before tracheal intubation (T), 5 minutes after the pneumoperitoneum (T), 5 minutes after PEEP ventilation (T), 30 minutes after PEEP ventilation (T), and 5 minutes after the end of pneumoperitoneum (T), respectively. The left and right ventricular myocardial performance index (LVMPI/RVMPI) was calculated.

Results: Finally, 60 patients were included in the analysis, including 28 patients in the early LV diastolic dysfunction group and 32 patients in the normal cardiac function group. Compared with those at T, mean arterial pressure (MAP), LVEF, mitral e', LVGLS, tricuspid e' and TAPSE were significantly lower in the normal cardiac function group at T, and the early LV diastolic dysfunction group at T, T, and T, and LVMPI, LVE/e', RVE/e', and RVMPI were significantly higher. At T, the LVE/e' and the RVE/e' were significantly higher in the early LV diastolic dysfunction group than those at T (LVE/e': 16.52±1.26 vs. 14.32±1.09, and RVE/e': 18.71±1.74 vs. 16.51±1.93, respectively, both P < 0.05), Mitral e' and tricuspid e' were significantly lower than those at T [mitral e' (m/s): 0.07±0.01 vs. 0.09±0.01, tricuspid e' (m/s): 0.06±0.01 vs. 0.08±0.01, both P < 0.05]. Compared with the normal cardiac function group, MAP, LVEF, mitral e', LVGLS, tricuspid e', and TAPSE at T, T, and T were significantly lower in the early LV diastolic dysfunction group, while LVMPI, LVE/e', RVE/e', and RVMPI were significantly higher. At T, the LVE/e' and the RVE/e' were significantly higher in the early LV diastolic dysfunction group than those in the normal cardiac function group (LVE/e': 16.52±1.26 vs. 9.87±1.25, RVE/e': 18.71±1.74 vs. 10.97±1.70, both P < 0.05). Mitral e' and tricuspid e' were significantly lower in the normal cardiac function group [mitral e' (m/s): 0.07±0.01 vs. 0.11±0.02, tricuspid e' (m/s): 0.06±0.01 vs. 0.10±0.02, both P < 0.05].

Conclusions: In early LV diastolic dysfunction patients, compared with patients with normal cardiac function, 5 cmHO PEEP can further exacerbate left and right myocardial systolic and diastolic function in patients during pneumoperitoneum; when the pneumoperitoneum was ended, 5 cmHO PEEP only worsen left and right myocardial diastolic function in patients, and did not affect left and right myocardial systolic function.