Background and Goal of Study：Fluid management was thought to have influence on postoperative nausea and vomiting (PONV). Pulse pressure variation (PPV) is a precise predictor of fluid responsiveness and a simple method on guiding fluid management. However, there is no study yet to examine the association between PPV and PONV.
Material s and Methods ：After reviewing medical records from September 1, 2014 to March 31, 2015, 229 adult patients (aged 20-79) who underwent schedule general abdominal surgery with arterial line setting were enrolled into this retrospective study. Patients with existing arrhythmic cardiac disease, the New York Heart Association functional classification III-IV, ASA physical status classiﬁcation IV-V, morbid obesity (BMI>35 kg m−2), marked anemia (Hb<9 g/dl), intraoperative desaturation (SpO2<92%), gastroesophageal reflux disease, preoperative use of opioids or antiemetics, pregnancy, and postoperative intensive care unit admission were excluded.
All patients fasted overnight and received no premedication. Standardized induction of general anesthesia was performed and maintained with Sevoflurane or Desflurane in an air-oxygen mixture. The modal value of PPV during operation was recorded every 15 minutes by trained nurse anesthetists and fluid management would initiate according to each anesthesiologist’s practice if PPV above 10-13%. In the end of the surgery, all patients applied Morphine I.V. patient-controlled analgesia and Ondansetron 4mg I.V. for PONV prophylaxis. Another group of trained nurse anesthetists assessed the incidence and severity of PONV 24 h after the surgery. Patients experiencing any degree of nausea or vomiting within the first 24h after surgery were classiﬁed as having PONV.
   In this analysis, patient-related variables were age, BMI (height and weight), ASA class, fasting duration, and postoperative 24h Morphine consumption. The anesthesia-related variable was the duration of anesthesia. Patient data were analyzed with Student’s unpaired t-test for continuous variables. Pulse pressure variations > 13% during intraoperative period and other variables, including intraoperative average PPV value, Apfel score, and laparoscopic or non-laparoscopic surgery method were subjected to multiple logistic regression to determine the association between pulse pressure variations and PONV. 
Results：Of 229 patients enrolled in the study, 59 (25.8%) developed PONV and were defined as PONV positive group. 138 among them (60.3%) were encountered at least one event of pulse pressure variations > 13% during intraoperative period and were defined as the PPV>13% group. The incidence of PONV in the PPV>13% group was significantly higher than in the PPV≦13% group (34.8% vs 12.1%; P<0.001). 
    The Apfel score, average PPV value, the proportion of patients who received laparoscopic surgery and encountered the events of PPV>13% were higher in the PONV positive group [Table 1]. Multivariate logistic regression analysis found PPV value >13% to be a predictive risk factor for PONV (P=0.009, adjusted odds ratio 3.198, 95% confidence interval 1.332-7.681) as well as the Apfel score (P= 0.010, adjusted odds ratio 1.606, 95% CI 1.118-2.307). The influence of intraoperative average PPV value was not significant (P= 0.85) [Table 2].
Discussion：Previous researches indicate intraoperative fluid administration may reduce the incidence of PONV. However, results are conflicting under some similar fluid administration protocol. How much fluid should be administrated intraoperatively to prevent PONV still remains controversial. The key point may be not how much fluid we give but how much fluid the patients actually need. PPV is a precise predictor of fluid responsiveness. Fluid deficit may exist perioperatively and we can use PPV to guide fluid management and to optimize fluid status. Our study indicates that transient PPV value exceeds 13% may have profound effect on PONV development. The anesthesiologists in our hospital are used to enhance fluid management if PPV above 10% during their daily practice to prevent episodes of PPV>13%. This may explain why the average PPV value does not exceed 13% in both groups and the influence of intraoperative average PPV value is not significant in this study. Our study also supports the idea that Apfel score is a predictive risk factor on PONV.

Conclusion：Our results demonstrate pulse pressure variation > 13% is a predictive risk factor of PONV even under routine PONV prophylaxis of Ondansetron 4mg I.V..

Intraoperative pulse pressure variation &gt; 13% is an independent risk factor for early postoperative nausea and vomiting in patients undergoing major abdominal surgery: a retrospective observational study

Intraoperative pulse pressure variation &gt; 13% is an independent risk factor for early postoperative nausea and vomiting in patients undergoing major abdominal surgery: a retrospective observational study

Intraoperative pulse pressure variation > 13% is an independent risk factor for early postoperative nausea and vomiting in patients undergoing major abdominal surgery: a retrospective observational study