Low‐frequency ventilation during cardiopulmonary bypass for lung protection: A randomized controlled trial

Abstract

Objective: Pulmonary dysfunction is a common complication in patients undergoing heart surgery. Current clinical practice does not include any specific strategy for lung protection. To compare the anti-inflammatory effects of low-frequency ventilation (LFV), as measured by nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) p65 pathway activation, for the entire cardiopulmonary bypass (CPB) vs both lungs left collapsed in patients undergoing coronary artery bypass grafting (CABG).Methods: Two groups parallel randomized controlled trial. The primary outcome was inflammation measured by NF-κB p65 activation in pre-and post-CPB lung biopsies.Secondary outcomes were additional inflammatory markers in both biopsy tissue and blood.Results: Thirty-seven patients were randomly allocated to LFV (18) and to both lungs left collapsed (19). The mean concentration of NF-κB p65 in the biopsies before chest closure (adjusted for pre-CPB concentration) was higher in the LFV group compared to both lungs left collapsed group but this was not significant (0.102, 95% confidence interval, −0.022 to 0.226, P = 0.104). There were no significant differences between groups in the other inflammatory markers measured in tissue and blood. Conclusions:In patients undergoing elective CABG, the use of LFV during CPB when compared to both lungs left collapsed does not seem to reduce inflammation in lung biopsies and blood.

The Effect of Low Tidal Volume Ventilation on Inflammatory Cytokines During Cardiopulmonary Bypass

“…Although studies have demonstrated that atelectasis and infection are reduced with low tidal volume ventilation [ 10 , 11 ] , we did not find such a difference in our ventilation and non-ventilation groups. Similar to our study, Fiorentino et al [ 12 ] did not find any difference between the TNF-α, IL-1β, IL-18, IL-6, IP-10, CXCL-8 and IL-10 levels of patients that did and did not receive ventilation support. An animal study supported these findings by reporting that IL-6, IL-8 and IL-10 levels were similar in all subject groups [ 7 ] .…”

Pulmonary protective ventilation during cardiopulmonary bypass revisited

“…In conclusion, we applaud Fiorentino et al for their important contribution. Far from being a denouement, these reported results raise very important questions.…”

“…Fiorentino et al present the readers with the results of their randomized controlled trial relating the effects of low frequency ventilation (LFV) on the pulmonary inflammatory pathways and indices of gas exchange. To their surprise, they observed no significant differences in outcomes between the cohort of interest (patients ventilated with air during CPB at 6 to 8 mL/kg, 5 breaths/minute, and zero end‐expiratory pressure) and the controls (patients whose lungs were disconnected from the breathing circuit and remained collapsed for the duration of CPB).…”

Multi-omic analysis of the effects of low frequency ventilation during cardiopulmonary bypass surgery

“…Furthermore, bronchial blood flow is reduced due 15 to haemodynamic and pulsatility changes during bypass and changes in vascular 16 resistances. These atelectatic and ischemic changes may promote tissue hypoxia, 17 oxidative stress and lung cellular damage [3][4][5][6]. Towards the end of CPB, full 18 ventilation is recommenced and pulmonary blood flow is restored with potential 19 injury by reperfusion including oxidative stress [7,8], and inflammatory cell 20 infiltration [9].…”