Effect of iron deficiency without anaemia on days alive and out of hospital in patients undergoing valvular heart surgery.

Comprehensive evidence regarding the treatment of non-anaemic iron deficiency in patients undergoing valvular heart surgery is lacking. This study aimed to investigate the association between non-anaemic iron deficiency and postoperative outcomes in these patients. We retrospectively analysed 321 patients of which 180 (56%) had iron deficiency (defined as serum ferritin < 100 ng.ml-1 or < 300 ng.ml-1 with transferrin saturation < 20%). While the iron-deficient group had lower pre-operative haemoglobin levels than the non-iron deficient group (median (IQR [range]) 134 (127-141 [120-172]) g.l-1 , 143 (133-150 [120-179]) g.l-1 , p = 0.001), there was no between-group difference in allogeneic red blood cell transfusion. Median (IQR [range]) days alive and out of hospital at postoperative day 90 was 1 day shorter in the iron-deficient group (80 (77-82 [9-85]) days vs. 81 (79-83 [0-85]) days, p = 0.026). In multivariable analysis, only cardiopulmonary bypass duration (p = 0.032) and intra-operative allogeneic red blood cell transfusion (p = 0.011) were significantly associated with reduced days alive and out of hospital at postoperative day 90. Iron deficiency did not exert any adverse influence on secondary outcomes except length of hospital stay. Our findings indicate that non-anaemic iron deficiency alone is not associated with adverse effects in patients undergoing valvular heart surgery when it does not translate into an increased risk of allogeneic transfusion.

Remote ischaemic conditioning for prevention of acute kidney injury after valvular heart surgery: a randomised controlled trial.

BACKGROUND: Repeated remote ischaemic conditioning (RIC) during weaning from cardiopulmonary bypass and in the early postoperative period may confer protection against acute kidney injury (AKI). We evaluated the effect of repeated RIC on the incidence of AKI in patients undergoing valvular heart surgery. METHODS: Patients were randomised into either the RIC (n=120) or control (n=124) group. A pneumatic tourniquet was placed on each patient's thigh. Upon removal of the aortic cross-clamp, three cycles of inflation for 5 min at 250 mm Hg (with 5 min intervals) were applied in the RIC group. Additionally, three cycles of RIC were repeated at postoperative 12 and 24 h. AKI was diagnosed based on the Kidney Disease: Improving Global Outcomes guideline. The incidences of renal replacement therapy, permanent stroke, sternal wound infection, newly developed atrial fibrillation, mechanical ventilation >24 h, and reoperation for bleeding during hospitalisation were recorded. RESULTS: The incidences of AKI were not significantly different between the control (19.4%) and RIC (15.8%) groups (a difference of 3.5 percentage points; 95% confidence interval: -6.8%-13.9%; P=0.470). Perioperative serum creatinine concentrations were similar in the control and RIC groups (P=0.494). Fluid balance, urine output, blood loss, transfusion, and vasopressor/inotropic requirements were not significantly different between the groups (all P>0.05). The occurrences of a composite of morbidity and mortality endpoints were not significantly different between the control (46.0%) and RIC (39.2%) groups (a difference of 6.8 percentage points; 95% confidence interval: -6.4%-20.0%; P=0.283). CONCLUSIONS: The results of our study do not support repeated RIC to decrease the incidence of AKI after valvular heart surgery. CLINICAL TRIAL REGISTRATION: NCT02720549.

Comparison of positive end-expiratory pressure-induced increase in central venous pressure and passive leg raising to predict fluid responsiveness in patients with atrial fibrillation.

BACKGROUND: Positive end-expiratory pressure (PEEP)-induced increase in central venous pressure (CVP) has been suggested to be a robust indicator of fluid responsiveness, with heart rhythm having minimal influence. We compared the ability of PEEP-induced changes in CVP with passive leg raising (PLR)-induced changes in stroke volume index (SVI) in patients with atrial fibrillation after valvular heart surgery. METHODS: In 43 patients with atrial fibrillation after cardiac surgery, PEEP was increased from 0 to 10 cm H2O for 5 min and changes in CVP were assessed. After returning the PEEP to 0 cm H2O, PLR was performed for 5 min and changes in SVI were recorded. Finally, 300 ml of colloid was infused and haemodynamic variables were assessed 5 min after completion of a fluid challenge. Fluid responsiveness was defined as an increase in SVI ≥10% measured by a pulmonary artery catheter. RESULTS: Fifteen (35%) patients were fluid responders. There was no correlation between PEEP-induced increases in CVP and changes in SVI after a fluid challenge (ß coefficient -0.052, P=0.740), whereas changes in SVI during PLR showed a significant correlation (ß coefficient 0.713, P<0.001). The area under the receiver operating characteristic curve of the PEEP-induced increase in CVP and changes in SVI during PLR for fluid responsiveness was 0.556 [95% confidence interval (CI) 0.358-0.753, P=0.549) and 0.771 (95% CI 0.619-0.924, P=0.004), respectively. CONCLUSIONS: A PEEP-induced increase in CVP did not predict fluid responsiveness in patients with atrial fibrillation after cardiac surgery, but increases in SVI during PLR seem to be a valid predictor of fluid responsiveness in this subset of patients.

Sodium bicarbonate does not prevent postoperative acute kidney injury after off-pump coronary revascularization: a double-blinded randomized controlled trial.

BACKGROUND: Acute kidney injury (AKI) is a common morbidity after off-pump coronary revascularization. We investigated whether perioperative administration of sodium bicarbonate, which might reduce renal injury by alleviating oxidative stress in renal tubules, prevents postoperative AKI in off-pump coronary revascularization patients having renal risk factors. METHODS: Patients (n=162) having at least one of the following AKI risk factors were enrolled: (i) age >70 yr; (ii) diabetes mellitus; (iii) chronic renal disease; (iv) congestive heart failure or left ventricular ejection fraction <35%; and (v) reoperation or emergency. Patients were evenly randomized to receive either sodium bicarbonate (0.5 mmol kg-1 for 1 h upon induction of anaesthesia followed by 0.15 mmol kg-1 h-1 for 23 h) or 0.9% saline. Acute kidney injury within 48 h after surgery was assessed using the Acute Kidney Injury Network criteria. RESULTS: The incidences of AKI were 21 and 26% in the bicarbonate and control groups, respectively (P=0.458). Serially measured serum creatinine concentrations and perioperative fluid balance were also comparable between the groups. The length of postoperative hospitalization and incidence of morbidity end points were similar between the groups, whereas significantly more patients in the bicarbonate group required prolonged mechanical ventilation (>24 h) relative to the control group (20 vs 6, P=0.003). CONCLUSIONS: Perioperative sodium bicarbonate administration did not decrease the incidence of AKI after off-pump coronary revascularization in high-risk patients and might even be associated with a need for prolonged ventilatory care. CLINICAL TRIAL REGISTRATION: NCT01840241.

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.

Myocardial protection by glucose-insulin-potassium in acute coronary syndrome patients undergoing urgent multivessel off-pump coronary artery bypass surgery.

BACKGROUND: The aim of this randomized and controlled trial was to investigate the effect of a glucose-insulin-potassium (GIK) solution on myocardial protection in acute coronary syndrome (ACS) patients undergoing urgent multivessel off-pump coronary artery bypass (OPCAB) surgery. METHODS: Sixty-six patients were randomly allocated either to receive 0.3 ml kg(-1) h(-2) GIK solution (potassium 80 mEq and regular insulin 325 IU in 500 ml of 50% glucose) or equivalent volume of normal saline (control) upon anaesthetic induction until 6 h after reperfusion. The primary endpoints were to compare the concentrations of creatine kinase-MB (CK-MB) and troponin-T between the groups after reperfusion. The secondary endpoints were to compare the incidences of postoperative troponin-T >0.8 ng ml(-1) and myocardial infarction (MI) between the groups. RESULTS: Highest CK-MB [8.7 (4.4) vs 13.1 (7.9) ng ml(-1), P=0.006] and troponin-T [0.20 (0.13-0.49) vs 0.48 (0.18-0.91) ng ml(-1), P<0.0001] values after reperfusion were significantly lower in the GIK group compared with the control group. The area under the curve of serially measured troponin-T was also significantly smaller in the GIK group compared with the control group [0.83 (0.43-1.81) vs 0.46 (0.31-1.00), P=0.036]. Significantly fewer patients in the GIK group showed troponin-T >0.8 ng ml(-1) after reperfusion compared with the control group (3 vs 11, P=0.033). The incidence of postoperative MI was similar between the groups. CONCLUSIONS: GIK administration in ACS patients undergoing urgent multivessel OPCAB significantly attenuated the degree of ensuing myocardial injury without complications related to glycaemic control. Clinical Trial Registry. URL: http://clinicaltrials.gov/ct2/show/NCT01384656?term=GIK+AND+OPCAB&rank=1. Unique identification number NCT01384656.

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.

Intraoperative epiaortic scanning for preventing early stroke after off-pump coronary artery bypass.

BACKGROUND: Numerous studies have demonstrated the accuracy of epiaortic ultrasound scanning (EAS) for assessing ascending aortic disease. It remains unclear whether EAS changes the incidence of perioperative stroke after off-pump coronary artery bypass (OPCAB). METHODS: We studied a retrospective cohort of 2292 patients who underwent isolated OPCAB from January 2001 to December 2011. Patients were retrospectively subdivided into two groups: the non-EAS group (n=1019) who underwent OPCAB under only intraoperative transoesophageal echocardiography and the EAS group (n=1273) who underwent OPCAB under EAS. RESULTS: In the non-EAS group, 317 (31.1%) patients underwent OPCAB with partial aortic clamping and 702 (68.9%) underwent OPCAB without partial aorta clamping. In the EAS group, 301 (23.7%) patients underwent OPCAB with partial aortic clamping and 972 (76.3%) underwent OPCAB without partial aortic clamping. The incidence of early stroke was not different statistically between the EAS and non-EAS groups [non-EAS 1.7% (17/1019) vs EAS 0.8% (10/1273); P=0.052]. However, in the subgroups of patients with partial aorta clamping, the incidence of the early stroke was significantly lower in the EAS group [2.8% (9/317) vs 0.7% (2/301) P=0.041]. CONCLUSIONS: EAS has a significant clinical benefit in reducing the incidence of early stroke in cases of partial aortic clamping in OPCAB. Therefore, EAS should be considered in patients who need partial aortic clamping in OPCAB.

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.