Is ultrafiltration volume a predictor of postoperative acute kidney injury in patients undergoing cardiopulmonary bypass?

INTRODUCTION

Intraoperative ultrafiltration (UF) is a procedure used during cardiopulmonary bypass (CPB) to reduce haemodilution and prevent excessive blood transfusion. However, the effect of UF volume on acute kidney injury (AKI) is not well established, and the results are conflicting. Additionally, there are no set indications for applying UF during CPB.

METHODS

This retrospective study analysed 641 patients who underwent coronary artery bypass graft (CABG) surgery with CPB. Perioperative parameters were extracted from the patients' records, and the UF volume was recorded. Acute Kidney Injury Network classification was used to define AKI. Univariable and multivariable logistic regression models were used to predict AKI while controlling for confounding factors.

RESULTS

The study enrolled patients with a mean age of 58.8 ± 11.1 years, 39.2% of whom were female. AKI occurred in 22.5% of patients, with 16.1% (103) experiencing stage I and 6.4% (41) experiencing stage II. The results showed a significant association between UF volume and the risk of developing AKI, with higher UF volumes associated with a higher risk of AKI. In the multivariable analysis, the other predictors of AKI included age, lowest mean arterial pressure (MAP), and red blood cell (RBC) transfusion during CPB.

CONCLUSION

The predictors of postoperative AKI in coronary CABG patients were the volume of UF, age, MAP, and blood transfusion during CPB.

Surgical repair of tetralogy of Fallot using autologous right atrial appendages: short- to mid-term results

OBJECTIVES

The prevention of pulmonary insufficiency (PI) is a crucial part of the tetralogy of Fallot repair. Many techniques have been introduced to construct valves from different materials for the right ventricular outflow tract, including the most commonly constructed monocusp valves. We are introducing a new bicuspid valve made intraoperatively using the autologous right atrial appendage (RAA) to prevent PI in these patients.

METHODS

The RAA valve was constructed and used in 21 patients with tetralogy of Fallot. The effective preservation of the native valve was impossible in all patients because of either a severe valve deformity or a small annulus. The RAA valve was created after ventricular septal defect closure and right ventricular outflow tract myectomy and was covered with a bovine transannular pericardial patch. The perioperative data were evaluated, and the echocardiography results were assessed immediately after operations and in follow-up with a median of 10.5 months. The data were retrospectively compared with 10 other patients with similar demographic data but with only transannular patches.

RESULTS

The mean age of the patients was 13.3 months. No mortality or related morbidity occurred after repair using the RAA valve. The PI severity early after the operation was trivial or no PI in 18 patients, and mild PI was observed in 3 patients, which progressed to moderate PI in one of them in the mean 12-month follow-up period. Fifteen patients had mild or no pulmonary stenosis, while moderate pulmonary stenosis was observed in 6 others. Compared with the other 10 patients with only transannular patches, the RAA valve patients had prolonged operative and clamping times, but no difference in postoperative course and shorter hospital stays. The degree of PI was, of course, significantly less in the RAA valve patients, but pulmonary stenosis was the same.

CONCLUSIONS

The RAA valve construction is a safe and effective technique to prevent PI after the tetralogy of Fallot repair, at least in terms of short- and mid-term results. A longer follow-up period is needed to confirm if this new valve can eliminate or significantly delay the need for pulmonary valve replacement in these patients.

Hidden pulmonary arteries in tetralogy of Fallot and pulmonary artery pressure in patients operated with a pulmonary artery

Introduction

The absence of a pulmonary artery is a rare congenital anomaly that occurs isolated or with other congenital cardiac disorders, particularly tetralogy of Fallot (TOF); meanwhile, a hidden pulmonary artery might exist and originate from a closed ductus arteriosus (DA), which can be stented to reach the artery.

Material and methods

This prospective study describes cardiac catheterization of nine TOF patients diagnosed with the absence of the left pulmonary artery before the operation. The patients were stratified into three groups: group one, whose closed DA was found and connected to the hidden pulmonary artery with a stent; group two, whose hidden pulmonary arteries were found via the pulmonary vein angiography; and group three, for whom we could not find the remnant of the DA, or our attempt to stent the DA to the hidden pulmonary artery was not successful. We also evaluated outcomes of six other surgically-corrected TOF patients who were operated with the absent left pulmonary artery.

Results

The first group included the patients aged 1, 24, and 30 months, whose CT angiography 6–9 months after stenting showed acceptable left pulmonary artery diameter for surgical correction, and the pulmonary vein angiography of the second group showed a hidden left pulmonary artery with a suitable diameter for surgical correction. However, we were unable to find or stent the DA of group three patients, aged 12, 38, 60, and 63 months. Earlier Angiography might have increased the chance of access to the hidden vessel. Apart from these three groups, follow-ups of six other patients previously corrected with only the right pulmonary artery revealed pulmonary artery hypertension in all patients.

Conclusion

The concealed pulmonary artery might be found, and stenting of the closed DA to it might be performed to improve the diameter of the diminutive pulmonary artery. This procedure may allow TOF total surgical correction with two pulmonary arteries. Besides, pulmonary vein angiography can reveal the hidden pulmonary artery.

The Effects of Dexmedetomidine Prescription in Paediatric Patients With Pulmonary Hypertension Under Congenital Heart Surgery

Anesthetized patient management for pediatric patients with pulmonary arterial hypertension (PAH) is a major challenge. The aim of this study was to evaluate the ability of dexmedetomidine to reduce pulmonary arterial hypertension in patients with pulmonary arterial hypertension undergoing cardiac surgery. Sixty-six patients with pulmonary arterial hypertension underwent the study. Patients were randomly divided into two groups: group D received a dexmedetomidine injection in a dose of 1 μg/kg in the first hour and then decreased to 0.5 μg/kg/hr, injection continued after surgery until extubation in the post-anesthetic care unit (PACU). Group C received normal saline 0.9% in a similar volume. Pulmonary artery systolic pressure (PASP) and systemic systolic blood pressure (SSBP) were recorded during and after the surgery in the postanesthetic care unit. Needing vasodilators, sedatives, extubation time, and the length of ICU stay were recorded for all patients. Patients in the dexmedetomidine group showed a significant reduction in Pulmonary artery systolic pressure and Pulmonary artery systolic pressure/systemic systolic blood pressure rates during surgery and during the first 24 hours in the post-anesthetic care unit (P<0.001). The dexmedetomidine group, in comparison with the control group, needed a significantly lower dose of a vasodilator (P<0.001) and a lower dose of sedation (P<0.001). It is concluded that the use of dexmedetomidine during the surgery in children with pulmonary hypertension reduces pulmonary artery systolic pressure during and after the surgery.

Comparison of Short-Term Results between Patients Undergoing Coronary Artery Bypass Graft with a Stent-Placement History and Patients Undergoing Primary Coronary Artery Surgery

Background: Percutaneous coronary intervention (PCI) has become the first-choice treatment strategy the world over for patients with chronic coronary artery disorders. This study compared the effects of previous PCI procedures on the short-term postoperative results of coronary artery bypass graft surgery (CABG). Methodsː This cross-sectional analytical study recruited 220 patients who underwent CABG in Afshar Hospital in the Iranian city of Yazd between March 2009 and February 2013. The mean postoperative morbidity and mortality rates, the mean postoperative left ventricular ejection fraction (LVEF), the mean hemorrhage volume, the mean serum urea level, and the mean length of stay in the intensive care unit (ICU) were compared between the PCI and non-PCI groups. Results: Among the 220 participants, 147(66.8%) were male and 73(33.2%) were female. The mean age of the study population was 59.41±10.52 years. There was no significant difference in the risk of mortality between the 2 groups (P=0.369). The mean serum urea level was 21.14±6.52 mg/dL in the PCI group and 14.45±1.08 mg/dL in the non-PCI group (P=0.016). The mean postoperative LVEF was 43.19±8.81% in the PCI group and 45.51±8.15% in the non-PCI group (P=0.044). The mean length of stay in the ICU was 3.34±1.23 days in the PCI group and 2.22±0.56 days in the non-PCI group (P<0.001). The mean hemorrhage volume was 1113.01±428.13 mL in the PCI group and 961.42±228.31 mL in the non-PCI group (P=0.027). Conclusion: Previous PCI procedures did not affect the post-CABG mortality rate; however, some postoperative results were worse in the PCI group than in the non-PCI group, which should be considered before the selection of the revascularization method.

Electrochemical monitoring of brain ascorbic acid changes associated with hypoxia, spreading depression, and seizure activity

In vivo electrochemistry has been a valuable tool in detecting real time neurochemical changes in extracellular fluid. Absolute selectivity has been difficult to achieve previously, but we report here a carbon fiber electrode and measurement technique which is specific for one oxidizable species: ascorbic acid. Ascorbic acid is highly concentrated in extra- as well as intracellular brain spaces, and appears to undergo dynamic changes in response to a variety of physiological and pathophysiological circumstances. Recent studies have implicated glutamatergic mechanisms which give rise to extracellular changes in brain ascorbate, and we confirm and extend these observations. Preliminary studies, directed towards examining ascorbic acid as an index and/or result of hypoxia, spreading depression, and seizure activity, have been undertaken and the results are reported herein.

The pharmacological profile of glutamate-evoked ascorbic acid efflux measured by in vivo electrochemistry

A recently described in vivo voltammetric electrode selectively records rapid changes in extracellular fluid (ECF) levels of ascorbic acid. Using this detector, the nature of glutamate-induced efflux of ascorbate into ECF was investigated using pharmacological tools. Ascorbate signals were shown to be directly related to amounts of microinjected glutamate. Blockers of glutamate reuptake, homocysteic acid and D,L-threo-beta-hydroxy-aspartic acid, virtually eliminate the ascorbate signal. A more specific reuptake blocker (the stilbene isothiocyano derivative (SITS) does not completely inhibit ascorbate efflux, suggesting that the glutamate uptake which is coupled to ascorbic acid exchange is both neuronal and glial in nature. Other pharmacological experiments indicate that excitatory amino acid receptors are not involved in the glutamate-elicited ascorbate efflux; it is primarily a function of the glutamate/ascorbate heteroexchange process as described earlier. The possible role(s) of brain ascorbate in the general functioning of the pervasive glutamate neurotransmitter systems are discussed.

Dynamic changes in extracellular fluid ascorbic acid monitored by in vivo electrochemistry

Voltammetric carbon fiber electrodes and a measuring protocol were designed to monitor extracellular changes in rat brain ascorbic acid (AA). Very fast variations of AA (less than 60 s in duration) as well as much slower changes can be followed. Basal and stimulated levels of AA, determined with the enzyme ascorbate oxidase (AAO), confirm the detection is selective for AA. Microinjections of glutamate (Glu) into various brain regions gave rise to rapid electrochemical signals ascribed to the efflux of AA into the extracellular fluid.