We studied respirophasic variation in carotid artery blood flow peak velocity (ΔVpeak-CA) measured by pulsed wave Doppler ultrasound as a predictor of fluid responsiveness in mechanically ventilated patients with coronary artery disease. Forty patients undergoing elective coronary artery bypass surgery were enrolled. Subjects were classified as responders if stroke volume index (SVI) increased ≥15% after volume expansion (6 ml kg⁻¹). The ΔVpeak-CA was calculated as the difference between the maximum and minimum values of peak velocity over a single respiratory cycle, divided by the average. Central venous pressure, pulmonary artery occlusion pressure, pulse pressure variation (PPV), and ΔVpeak-CA were recorded before and after volume expansion. PPV and ΔVpeak-CA correlated significantly with an increase in SVI after volume expansion. Area under the receiver-operator characteristic curve (AUROC) of PPV and ΔVpeak-CA were 0.75 [95% confidence interval (CI) 0.59–0.90] and 0.85 (95% CI 0.72–0.97). The optimal cut-off values for fluid responsiveness of PPV and ΔVpeak-CA were 13% (sensitivity and specificity of 0.74 and 0.71) and 11% (sensitivity and specificity of 0.85 and 0.82), respectively. In a subgroup analysis of 17 subjects having pulse pressure hypertension (≥ 60 mm Hg), PPV failed to predict fluid responsiveness (AUROC 0.70, P=0.163), whereas the predictability of ΔVpeak-CA remained unchanged (AUROC 0.90, P=0.006). Doppler assessment of respirophasic ΔVpeak-CA seems to be a highly feasible and reliable method to predict fluid responsiveness in mechanically ventilated patients undergoing coronary revascularization. NCT 01836081.

Dexmedetomidine, an α2 adrenergic receptor agonist, has analgesic, sedative and sympatholytic properties, with a lack of respiratory depression. It is licensed only for intensive care sedation. The objective of this study is to investigate whether intravenous (i.v.) patient-controlled analgesia (PCA) with dexmedetomidine added to a fentanyl-based drug mixture could reduce postoperative nausea and vomiting (PONV) in highly susceptible patients undergoing lumbar spinal surgery. A randomised, double-blinded study. At a tertiary university hospital between September 2012 and September 2013. One hundred and eight patients undergoing level 1 or 2 posterior lumbar spinal fusion who had at least three risk factors for PONV (female, nonsmoker, use of postoperative opioids) were randomised into two groups. Three patients were excluded from analysis and 105 patients completed the study. Patients received either dexmedetomidine 0.5 μg kg⁻¹ i.v. (dexmedetomidine group) or 0.9% normal saline (control group) 30 min before the completion of surgery followed by fentanyl 0.5 μg kg⁻¹ and 4 mg ondansetron. Postoperatively, the PCA (fentanyl 10 μg kg⁻¹ with 120 mg ketorolac, with or without dexmedetomidine 10 μg kg⁻¹ made up to a total volume of 100 ml) was programmed to deliver 1 ml bolus (lockout 15 min) with a continuous background infusion of 2 ml h⁻¹. The PCA was used for the first 48 h postoperatively. The incidence and severity of PONV, cumulative dose of PCA fentanyl consumed and pain scores were assessed for 48 h. The dexmedetomidine group experienced less nausea during the time interval 1 to 3 h postoperatively compared with the control group [odds ratio (OR) 0.32; 95% confidence interval (CI) 0.13 to 0.77; P = 0.019]. The intensity of nausea between the groups during the first 48 h was comparable, but the dexmedetomidine group had a lower incidence of moderate to severe nausea (OR 0.28; 95% CI 0.12 to 0.67; P < 0.003). Pain scores were not significantly different between the groups, but patients in the dexmedetomidine group required less fentanyl and less rescue analgesia in the first 12 h. Compared with the control group, patients in the dexmedetomidine group experienced almost twice as many episodes of hypotension and bradycardia, but this failed to reach statistical significance. Adding dexmedetomidine to a fentanyl-based PCA drug mixture reduces the frequency and severity of acute postoperative nausea in highly susceptible patients. Clinicaltrials.gov identifier: NCT01840254.

The aim of this prospective trial was to investigate the ability of pulse pressure variation (PPV) and corrected flow time (FTc) to predict fluid responsiveness in the prone position. Forty-four patients undergoing lumbar spine surgery in the prone position on a Wilson frame were prospectively studied. PPV and FTc were measured before and after a colloid bolus (6 ml kg⁻¹) both in the supine and in the prone positions. Fluid responsiveness was defined as an increase in the stroke volume index of ≥10% as measured by oesophageal Doppler. In the supine position, 26 patients were responders and the areas under the curve (AUC) of the receiver-operator characteristic (ROC) curves of PPV and FTc were 0.935 [95% confidence interval (CI): 0.870–0.999, P<0.001] and 0.822 (95% CI: 0.682–0.961, P<0.001), respectively. The optimal cut-off PPV and FTc values were 15% (sensitivity 73%, specificity 94%) and 358 ms (sensitivity 88%, specificity 78%), respectively. In the prone position, 34 patients were responders and the AUCs of PPV and FTc were 0.969 (95% CI: 0.912–1.000, P<0.001) and 0.846 (95% CI: 0.706–0.985, P=0.001), respectively. The optimal cut-off PPV and FTc values were 14% (sensitivity 97%, specificity 90%) and 331 ms (sensitivity 77%, specificity 90%), respectively. While the predictability of PPV was significantly higher than that of FTc in the prone position, both variables showed high predictability and remained as useful indices for guiding fluid therapy in prone patients with minimal alterations in their optimal cut-off values to predict fluid responsiveness. URL: http://www.clinicaltrials.gov/ct2/show/NCT01646359?term=NCT01646359&rank=1 and unique identification number NCT01646359.

We evaluated the effect of ketamine as an adjunct to a fentanyl-based i.v. patient-controlled analgesia (IV-PCA) on postoperative nausea and vomiting (PONV) in patients at high risk of PONV undergoing lumbar spinal surgery. Fifty non-smoking female patients were evenly randomized to either the control or ketamine group. According to randomization, patients received either ketamine 0.3 mg kg⁻¹ i.v. or normal saline after anaesthetic induction with fentanyl-based IV-PCA either with or without ketamine mixture (3 mg kg⁻¹ in 180 ml). The incidence and severity of PONV, volume of IV-PCA consumed, and pain intensity were assessed in the postanaesthesia care unit, and at postoperative 6, 12, 24, 36, and 48 h. The overall incidence of PONV during the first 48 h after surgery was similar between the two groups (68 vs 56%, ketamine and control group, P=0.382). The total dose of fentanyl used during the first 48 h after operation was lower in the ketamine group than in the control group [mean (sd), 773 (202) μg vs 957 (308) μg, P=0.035]. The intensity of nausea (11-point verbal numerical rating scale) was higher in the ketamine group during the first 6 h after operation [median (interquartile range), 6 (3–7) vs 2 (1.5–3.5), P=0.039], postoperative 12–24 h [5 (4–7) vs 2 (1–3), P=0.014], and postoperative 36–48 h [5 (4–7) vs 2 (1–3), P=0.036]. Pain intensities were similar between the groups. Ketamine did not reduce the incidence of PONV and exerted a negative influence on the severity of nausea. It was, however, able to reduce postoperative fentanyl consumption in patients at high-risk of PONV.