Is the reduced risk of post-operative nausea and vomiting in low flow anesthesia applications associated with pre-operative neutrophil/lymphocyte ratio values?

PONV risk in low flow anesthesia applications

Abstract

Background/Aim: Post-operative nausea and vomiting (PONV) are defined as nausea and/or vomiting occurring within the first 24 h after surgery and are often observed in the first 2 h after surgery. Only a few previous studies on the use of low fresh gas flow that reduces inhaler agent consumption in laparoscopic cholecystectomy patients at high risk of PONV have been published. Our study aimed to determine the incidence of PONV in the first 30 min and again at 24 h in cases of laparoscopic cholecystectomy in which we applied low fresh gas flow (1 L/min). In addition, we wanted to predict whether the pre-operative neutrophil/lymphocyte ratio (NLR) ≥2 is a risk factor for PONV in our patients to whom we applied low fresh gas flow.

Methods: For our prospective cohort study, 80 cases between the ages of 18 and 65, had American Society of Anesthesiologists (ASA) scores of I and II, and who had been scheduled to undergo elective laparoscopic cholecystectomy were included in the study. The NLR limit (calculated by dividing the neutrophil count obtained from the complete blood count before surgery by the lymphocyte count) calculated in the pre-operative period after a patient’s informed consent was obtained was accepted as 2 [5]. Patients were classified into two groups: (1) NLR-I with NLR <2 and (2) NLR-II with NLR ≥2. Premedication was not used in either group.

Results: A total of 80 patients were included in the study. They were divided into two groups for classification purposes: (1) NLR-I (n=40) and (2) NLR-II (n=40). The characteristics of the patients in both groups, such as gender distribution, ASA scores, smoking status, mean age, and body mass index (BMI) values, were not different. Sevoflurane consumption in the groups was similar (P=0.169). The time required to complete surgery was longer in the NLR-II group (P=0.025). Nausea/vomiting and antiemetic use were similar in the NLR-I and NLR-II groups in which low fresh gas flow was applied in the first 30 min and 24 h (P=0.500). Although nausea/vomiting was more common in the female and non-smoking group in the first 30 min and 24 h, it was not statistically significantly different from males and smoking groups (P=0.325). However, nausea/vomiting was more common and significantly different in the ASA II versus the ASA I group (P=0.046). The time required to complete surgery was longer, and sevoflurane consumption was higher in patients with nausea and vomiting (P=0.001).

Conclusions: Pre-operative NLR as classified by the two groups was not associated with an increase in the risk of PONV in patients to whom we applied low fresh gas flow. A decrease in sevoflurane consumption due to low fresh gas flow may lead to a reduction in the risk of PONV in at-risk patients.