Young-Lan Kwak

The effect of phenylephrine and norepinephrine in patients with chronic pulmonary hypertension

In this study the effect of phenylephrine and norepinephrine for the treatment of systemic hypotension were evaluated in patients with chronic pulmonary hypertension. When systemic hypotension (systolic arterial pressure < 100 mmHg) occurred following induction of anaesthesia, either phenylephrine or norepinephrine were infused in a random manner to raise the systolic blood pressure by 30% and 50% above baseline values. Norepinephrine decreased the ratio of pulmonary arterial pressure to systemic blood pressure without a change in cardiac index. However, phenylephrine did not increase arterial blood pressure by more than 30% from baseline in one‐third of patients and decreased cardiac index without a significant decrease in ratio of pulmonary arterial pressure to systemic blood pressure. These vasoconstrictors showed different systemic and pulmonary haemodynamic effects in patients with chronic pulmonary hypertension as compared to acute pulmonary hypertension. Norepinephrine was considered to be preferable to phenylephrine for the treatment of hypotension in patients with chronic pulmonary hypertension.

Anesthetics influence the incidence of acute kidney injury following valvular heart surgery

Propofol has been shown to provide protection against renal ischemia/reperfusion injury experimentally, but clinical evidence is lacking. Here we studied the effect of propofol anesthesia on the occurrence of acute kidney injury following heart surgery with cardiopulmonary bypass. One hundred and twelve patients who underwent valvular heart surgery were randomized to receive either propofol or sevoflurane anesthesia, both with sufentanil. Using Acute Kidney Injury Network criteria, significantly fewer patients developed acute kidney injury postoperatively in the propofol group compared with the sevoflurane group (6 compared with 21 patients). The incidence of severe renal dysfunction was significantly higher in the sevoflurane group compared with the propofol group (5 compared with none). The postoperative cystatin C was significantly lower in the propofol group at 24 and 48 h. Serum interleukin-6 at 6 h after aorta cross-clamp removal, C-reactive protein at postoperative day 1, and segmented neutrophil counts at postoperative day 3 were also significantly lower in the propofol group. Thus, propofol anesthesia significantly reduced the incidence and severity of acute kidney injury in patients undergoing valvular heart surgery with cardiopulmonary bypass compared with sevoflurane. This beneficial effect of propofol may be related to its ability to attenuate the perioperative increase in proinflammatory mediators.

Validation of pulse pressure variation and corrected flow time as predictors of fluid responsiveness in patients in the prone position

BACKGROUND 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. METHODS 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. RESULTS 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. CONCLUSIONS 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. Clinical trial registration URL: http://www.clinicaltrials.gov/ct2/show/NCT01646359?term=NCT01646359&rank=1 and unique identification number NCT01646359.

Effect of combined remote ischemic preconditioning and postconditioning on pulmonary function in valvular heart surgery.

BACKGROUND The aim of this study was to evaluate the lung-protective effect of combined remote ischemic preconditioning (RIPCpre) and postconditioning (RIPCpost) in patients undergoing complex valvular heart surgery. METHODS In this randomized, placebo-controlled, double-blind trial, 54 patients were assigned to an RIPCpre plus RIPCpost group or a control group (1:1). Patients in the RIPCpre plus RIPCpost group received three 10-min cycles of right-side lower-limb ischemia of 250 mm Hg at both 10 min after anesthetic induction and weaning from cardiopulmonary bypass. The primary end point was to compare postoperative Pao(2)/Fio(2). Secondary end points were to compare pulmonary variables, incidence of acute lung injury, and inflammatory cytokines. RESULTS In both groups, Pao(2)/Fio(2) at 24 h postoperation was significantly decreased compared with each corresponding baseline value. However, intergroup comparisons of pulmonary variables, including Pao(2)/Fio(2) and incidence of acute lung injury, revealed no significant differences. Serum levels of IL-6, IL-8, IL-10, and tumor necrosis factor-α were all significantly increased in both groups compared with each corresponding baseline value, without any significant intergroup differences. There were also no significant differences in transpulmonary gradient of IL-6, IL-10, and tumor necrosis factor-α between the groups. CONCLUSIONS RIPCpre plus RIPCpost as tested in this randomized controlled trial did not provide significant pulmonary benefit following complex valvular cardiac surgery.

Effect of low-dose ketamine on inflammatory response in off-pump coronary artery bypass graft surgery.

BACKGROUND Off-pump coronary artery bypass graft surgery (OPCAB) is still associated with a marked systemic inflammatory response. The aim of this study was to investigate whether pre-emptive, low dose of ketamine, which has been reported to have anti-inflammatory activity in on-pump coronary artery bypass surgery, could reduce inflammatory response in low-risk patients undergoing OPCAB. METHODS In this prospective randomized-controlled trial, 50 patients with stable angina and preserved myocardial function undergoing OPCAB were randomly assigned to receive either 0.5 mg kg(-1) of ketamine (Ketamine group, n=25) or normal saline (Control group, n=25) during induction of anaesthesia. Inflammatory markers including C-reactive protein (CRP), interleukin (IL)-6, tumour necrosis factor-alpha (TNF-alpha), and cardiac enzymes were measured previous to induction (T1), 4 h after surgery (T2), and the first and second days after the surgery (T3 and T4). RESULTS There were no significant intergroup differences in the serum concentrations of the CRP, IL-6, and TNF-alpha and cardiac enzymes. Pro-inflammatory markers and cardiac enzymes, except TNF-alpha, were all increased after the surgery compared with baseline values in both groups. CONCLUSIONS Low-dose ketamine administered during anaesthesia induction did not exert any evident anti-inflammatory effect in terms of reducing the serum concentrations of pro-inflammatory markers in low-risk patients undergoing OPCAB.

Comparison of the Effects of Nicardipine and Sodium Nitroprusside for Control of Increased Blood Pressure after Coronary Artery Bypass Graft Surgery

We compared the haemodynamic effects of nicardipine and sodium nitroprusside after coronary artery bypass graft surgery. When post-surgery systolic blood pressure reached > 150 mmHg, patients were randomly given nicardipine (N group, n = 26) or sodium nitroprusside (S group, n = 21). The drugs were infused at a rate of 2 μg/kg per min for 10 min. If the target blood pressure (120-140 mmHg) was not achieved, the infusion rate was increased by 1 üg/kg per min every 10 min. Cardiac and stroke volume indices had increased significantly in the N group after 10 min and in both groups after 60 min. The infusion duration and total dose of drug were significantly lower in the N group compared with the S group. Nicardipine infusion controlled post-operative hypertension more rapidly and was superior to sodium nitroprusside in maintaining left ventricular performance immediately after drug infusion.

Effect of ketamine as an adjunct to intravenous patient-controlled analgesia, in patients at high risk of postoperative nausea and vomiting undergoing lumbar spinal surgery

BACKGROUND 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. METHODS 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. RESULTS 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. CONCLUSIONS 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.

Haemodynamic effects of a milrinone infusion without a bolus in patients undergoing off-pump coronary artery bypass graft surgery

The haemodynamic effects of a continuous infusion of milrinone without an initial bolus dose were evaluated in patients undergoing off‐pump coronary artery bypass graft surgery. After internal mammary artery harvest, milrinone 0.5 μg.min−1.kg−1 (29 patients) or a normal saline infusion (33 patients) was started and continued until all graft anastomoses were completed. Haemodynamic variables were recorded before application of the tissue stabiliser, at 1, 3, 5 and 10 min after the application of the stabiliser, and after its removal. The administration of a milrinone infusion was associated with a smaller decrease in cardiac output and mixed venous oxygen saturation during all the coronary artery anastomoses, with no severe complications and a decreased dose of norepinephrine infused to maintain systemic arterial pressure.

Peri‐operative oral triiodothyronine replacement therapy to prevent postoperative low triiodothyronine state following valvular heart surgery

This study evaluated the effect of oral triiodothyronine (T3) replacement therapy, starting on the day of the surgery, on thyroid hormone concentrations and clinical outcome in high‐risk patients undergoing valvular heart surgery. Fifty patients were randomly allocated to either T3 or placebo. In the treatment (T3) group patients received 20 μg of oral or nasogastric T3 every 12 h starting just before induction of anaesthesia and until the first day after surgery. T3 concentrations were significantly higher in the T3 group than the placebo group from 1 to 36 h after removal of the aortic cross clamp. The number of patients requiring vasopressin after discontinuing cardiopulmonary bypass was significantly greater in the placebo group than the T3 group. Significantly fewer patients required vasopressors in the T3 group on the first day after surgery.

Respirophasic carotid artery peak velocity variation as a predictor of fluid responsiveness in mechanically ventilated patients with coronary artery disease

BACKGROUND 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. METHODS 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. RESULTS 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). CONCLUSIONS 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. CLINICAL TRIAL REGISTRATION NCT 01836081.