The Evaluation of Factors Affecting Hemodynamic Variability in Mechanically-Ventilated Patients After Cardiac Surgery

Comparison of the Effect of Heparinized Normal Saline Solution Versus Saline Solutions in Arterial and Central Venous Catheters on Complete Blood Count After Cardiac Surgery

Background

Heparinized and saline solutions can prevent clot formation in arterial and central venous catheters. However, heparin can decrease the platelet count and induce thrombocytopenia. Patients undergoing cardiac surgeries are more likely to develop heparin-induced thrombocytopenia.

Objectives

This study aimed to investigate the effect of heparinized and saline solutions of arterial and central venous catheters on complete blood count (CBC) after cardiac surgery.

Methods

This randomized controlled trial was conducted on 100 participants. All subjects underwent cardiac surgery at Rajaie Cardiovascular, Medical, and Research Center, Tehran, Iran. Patients were randomly divided into two groups intervention (A) for whom heparinized normal saline solution was used to maintain central arterial and venous catheters, and control (B) for whom normal saline solution was used. The CBC of subjects was monitored for three days (before surgery and the first and second days after surgery).

Results

In the present study, there were no significant differences between CBC, white blood cell differential count, prothrombin time, partial thromboplastin time (PTT), and international normalized ratio in groups A and B. However, we found significant differences in platelet count (P = 0.049), red blood cell count (P = 0.0001), hemoglobin (P = 0.0001), and hematocrit (P = 0.0001) between before surgery and the second day after surgery in group A. Platelet count (P = 0.027) and PTT (P = 0.0001) before and after surgery were significantly different in group B.

Conclusions

According to the results of this study, normal saline solution catheters have fewer side effects and can be a suitable replacement for heparinized catheters.

Evaluation of the Relationship Between Changes in Potassium Concentration and Arrhythmia During Coronary Artery Bypass Grafting Surgery

Background

Coronary artery bypass grafting (CABG) surgery is a treatment option for coronary artery diseases. Cardiac arrhythmias during CABG surgery can lead to serious complications. Potassium ion concentration is a factor involved in such arrhythmias.

Objectives

This study aimed to investigate the relationship between potassium concentration and cardiac arrhythmias in CABG surgery.

Methods

This descriptive cross-sectional study was performed on 60 patients with the American Society of Anesthesiologists class I, II, and III undergoing CABG surgery at Golestan Hospital, Ahvaz, Iran. All patients underwent general anesthesia, and ventilator control was achieved by mechanical ventilation. The on-pump method was used for CABG. Potassium levels were measured at several time points during surgery. All cardiac arrhythmias were recorded. Mean arterial pressure (MAP), serum level of potassium, blood sugar, blood urea nitrogen (BUN), creatinine, calcium, magnesium, hemoglobin (Hb), and sodium were also recorded.

Results

The mean age of the patients was 60.87 ± 7.35 years, and 45% of the subjects were female. Moreover, there was no statistically significant difference between the patients. There was a significant relationship between the changes in MAP, potassium, blood sugar, BUN, creatinine, calcium, and magnesium with the incidence of cardiac arrhythmias (P < 0.05). However, no significant relationship was noted between Hb and sodium levels with the incidence of cardiac arrhythmias (P < 0.05).

Conclusions

The changes in potassium levels increase the risk of cardiac arrhythmias and their complications.

Glycemic Control in Coronary Artery Bypass Graft Surgery: A Different Perspective

Background

Hyperglycemia during coronary artery bypass graft surgery (CABG) strongly predicts intra- and post-operative adverse consequences.

Objectives

This study aimed to evaluate the quality of glycemic management during CABG in an academic center regarding peripheral blood and coronary sinus values.

Methods

This prospective descriptive study encompassed 55 eligible patients undergoing on-pump CABG surgery in 2020. Peripheral blood glucose (BG) was measured four times, before anesthesia induction (T0), before cardiopulmonary bypass pump (CPB) (T1), during CPB (T2), at the end of CPB (T3), and at the end of surgery (T4). The surgeon also took a sample of the coronary sinus BG.

Results

The BG variations from T0 to T4 were statistically significant (P < 0.0001). The higher values detected in the ASA class III compared to ASA classes II were statistically significant at T1 (P = 0.01) and T2 (P = 0.025): patients with the higher BMI showed the higher levels of BG. In this regard, the differences were significant at T0 (P = 0.0001), T2 (P = 0.004), and T3 (P = 0.015). Regarding coronary sinus, the mean BG was 222.18 ± 75.74 mg/dL. It was also observed that the ASA class III (P = 0.001), longer duration of CPB (P = 0.021), higher IV fluid volume administrated during surgery (P = 0.023), higher BMI (P = 0.0001), and less urine volume at the end of surgery (P = 0.049) were significantly associated with the higher BG of the coronary sinus.

Conclusions

The existing glycemic management protocols on the CABG patients were acceptable in our hospital. However, the BG level of the coronary sinus was higher than the peripheral one.

Investigating the Effect of Expiratory Time Constant on Outcome in Intubated Patients with Acute Respiratory Failure Caused by COVID-19 in Critical Care Unit: A Research Study

Background

The coronavirus disease 2019 (COVID-19) has a high prevalence and mortality worldwide. Thousands of patients with acute respiratory failure caused by COVID-19 are daily hospitalized in intensive care units (ICUs) around the world. Many of these patients require full mechanical respiratory support and long-term ventilator use. Using different ventilators and calculating important variables can be helpful in meeting therapeutic needs of patients.

Objectives

The aim of present study was to investigate the effect of expiratory time constant (RCEXP) on the course of treatment and duration of mechanical ventilation in patients with acute respiratory failure hospitalized in ICU.

Methods

The present cross-sectional study was conducted on 60 patients with acute respiratory failure who were hospitalized in the ICU and underwent mechanical ventilation due to COVID-19 in the first six months of 2020. The variables of RCEXP, lung compliance and lung resistance in all patients were recorded daily and analyzed. Then, based on clinical outcome, the patients were divided into two groups: the patients with wean outcome (N = 40) and those with death outcome (N = 20).

Results

The mean ± SD of lung compliance in patients who were separated from ventilator and patients with death outcome were 74.73 (18.58) mL/cm H₂O and 36.92 (10.56) mL/cm H₂O, respectively, which was statistically significant (P = 0.001). The mean ± SD of lung resistance in patients who were separated from ventilator and patients with death outcome were calculated at 9.25 (4.62) and 14 (6.5), respectively, which was statistically significant (P = 0.015). Also, there was a statistically significant difference between the two groups in terms of mean ± SD of RCEXP (0.67 (0.23) vs. 0.49 (0.19), P = 0.010).

Conclusions

According to the results of this study, there was a significant difference between high resistance, low compliance, RCEXP, and weaning success of intubation in patients hospitalized in the ICU.

Comparison of Bioimpedance Versus Pulse Contour Analysis for Intraoperative Cardiac Index Monitoring in Patients Undergoing Kidney Transplantation

Background

Cardiac index (CI; cardiac output indexed to body surface area) is routinely measured during kidney transplant surgery. Bioimpedance cardiometry is a transthoracic impedance as the non-invasive alternative for hemodynamic monitoring, using semi-invasive uncalibrated pulse wave or contour (UPC) analysis.

Objectives

We performed a cross-sectional observational study on 50 kidney transplant patients to compare the CI measurement agreement, concordance rate, and trending ability between bioimpedance and UPC analysis.

Methods

For each patient, CI was measured by bioimpedance analysis (ICON^TM) and UPC analysis (EV1000^TM) devices at three time points: after induction, during incision, and at reperfusion. The device measurement accuracy was assessed by the bias value, limit of agreement (LoA), and percentage error (PE) using Bland-Altman analyses. Trending ability was assessed by angular bias and polar concordance through four-quadrant and polar plot analyses.

Results

From each time point and pooled measurement, the correlation coefficients were 0.267, 0.327, 0.321, and 0.348. Bland-Altman analyses showed mean bias values of 1.18, 1.06, 1.48, and 1.30, LoA of -1.35 to 3.72, -1.39 to 3.51, -1.07 to 4.04, and -1.17 to 3.78, and PE of 82.21, 78.50, 68.74, and 74.58%, respectively. Polar plot analyses revealed angular bias values of -10.37º, -15.01º, -18.68º, and -12.62º, with radial LoA of 89.79º, 85.86º, 83.38º, and 87.82º, respectively. The four-quadrant plot concordance rates were 70.77, 67.35, 65.90, and 69.79%. These analyses showed poor agreement, weak concordance, and low trending ability of bioimpedance cardiometry to UPC analysis.

Conclusions

Bioimpedance and UPC analysis for CI measurements were not interchangeable in patients undergoing kidney transplant surgery. Cardiac index monitoring using bioimpedance cardiometry during kidney transplantation should be interpreted cautiously because it showed poor reliability due to low accuracy, precision, and trending ability for CI measurement.