Peter R. Lichtenthal

A clinical evaluation of a blood conservation device in medical intensive care unit patients

ObjectivesThis study was designed to a) document the efficacy of a device intended to conserve blood in critically ill patients; b) determine the effect of this blood conservation on hemoglobin concentration and the need for blood transfusions; c) determine if the blood conservation device resulted in interference with arterial pressure waveforms; d) determine if use of the blood conservation device resulted in a difference in the number of accidental needle punctures suffered by healthcare workers. DesignProspective, randomized, controlled trial. A clinical trial using prospective, random allocation of consecutive eligible patients. SettingThe medical intensive care unit (ICU) of a university hospital located in a large metropolitan area. PatientsA total of 100 patients who were admitted to the medical ICU, required arterial line monitoring for clinical purposes, and were managed by the ICU medical service. Exclusion criteria included active bleeding or chronic renal failure at the time of ICU admission. InterventionsPatients in the experimental group had a blood conservation device incorporated into the arterial pressure monitoring system, while patients in the control group received a conventional arterial pressure monitoring system. Measurements and Main ResultsData gathered included: age; gender; ICU discharge status; the duration of ICU stay; time in the study; volume of all blood drawn, discarded, or lost due to leakage; hemoglobin concentrations; blood transfusions; and accidental needle injuries. Arterial pressure waveforms were recorded and inspected for dampening or other deformation. Mean hemoglobin concentrations were compared on ICU admission and at 12-hr intervals. Demographic and clinical characteristics of the two groups were not significantly different. The volume of blood drawn and discarded from arterial catheters was significantly lower in the blood conservation group (blood conservation device: 5.7 ± 7.5 mL; control: 96.4 ± 88.5 mL; p < .0001), as was the total volume of blood discarded (blood conservation device: 19.4 ± 47.4 mL; control: 103.5 ± 99.9 mL; p < .0001). Mean hemoglobin concentration on admission was similar in the two groups (blood conservation device group: 11.8 ± 2.5 g/dL; control group: 12.6 ± 2.3 g/dL). In both groups, the mean hemoglobin concentration declined most rapidly in the first 24 hrs of ICU care and, thereafter, declined more slowly. Although the mean hemoglobin concentration was higher in the blood conservation group after 6 days, statistical significance was not reached until 9.5 days of ICU care. The mean change in hemoglobin concentration (overall: 1.2 ± 2.2 g/dL) during the study represents a statistically significant (p < .0001) decrease of 9.7%. Hemoglobin concentration during the study decreased by 1.4 ± 2.2 g/dL in the control group and 1.0 ± 2.3 g/dL in the blood conservation group (p = nonsignificant). Univariate and multiple regression analysis demonstrated discarded blood volume to be a significant and independent predictor of the decline in hemoglobin concentration. Transfusion requirements were similar in both groups. The blood conservation system did not alter or interfere with pressure waveforms. There were no accidental needle injuries noted.

Respiratory management after cardiac surgery with inhalation anesthesia.

Improvements in cardiac surgery techniques and anesthetic management have given us cause to re-evaluate the necessity for postoperative mechanical ventilation and delayed extubation after open-heart surgery with inhalational anesthesia. One hundred consecutive patients undergoing various types of cardiac surgery were entered into this study; 94 patients met the requirements for spontaneous ventilation in the immediate postoperative time period and mechanical ventilation was not utilized. Of these 94 patients, 40 (45%) met extubation requirements within 90 min and were subsequently extubated. No patient required reintubation. Six (6%) patients failed to meet the requirements for spontaneous ventilation and, therefore, required mechanical ventilatory assistance postoperatively. In the majority of cardiac patients, the anesthetic technique determines postoperative ventilatory needs. Very poor preoperative physical status and unusually long procedures, however, will probably preclude early extubation or spontaneous ventilation and dictate the need for mechanical ventilation regardless of the anesthetic technique.

Clinical Evaluation of the Relative Effectiveness of Multidose Crystalloid and Cold Blood Potassium Cardioplegia in Coronary Artery Bypass Graft Surgery: A Nonrandomized Matched-Pair Analysis

Controversy exists concerning the most effective method of myocardial protection during coronary artery bypass graft operations. Accordingly, we performed a matched-pair analysis between 25 patients receiving multidose hypothermic potassium crystalloid cardioplegia and 25 other patients receiving cold blood potassium cardioplegia. Patients were matched on the basis of preoperative ejection fraction (EF) and the number of anatomically similar stenotic coronary arteries. The adequacy of myocardial protection was assessed by serial perioperative determinations of radionuclide ventriculography, hemodynamic measurements, analyses of electrocardiograms and serum levels of MB-CK. We found that the level of myocardial protection was similar between unstratified groups. However, when subgroups were selected on the basis of prolonged aortic cross-clamp time (greater than ninety minutes) or impaired preoperative left ventricular function (EF less than 40%), there was a suggestion that cold blood cardioplegia may be advantageous.

Dose-Related Prolongation of the Bleeding Time by Intravenous Nitroglycerin

The effects of intravenous nitroglycerin (NTG) upon the bleeding time, platelet aggregation response, and plasma 6-keto-PGF1α concentration were measured in 17 patients about to undergo coronary bypass grafting. NTG produced a dose-related prolongation of the bleeding time that correlated with the accompanying decrease in systolic blood pressure. Platelet aggregation was not affected and measurements of 6-keto-PGF1α Failed to reveal detectable levels (< 10 pg/ml) either before or after NTG infusion. This suggests that the prolonged bleeding time associated with NTG infusion may be due to vasodilation and increased venous capacitance, rather than altered vascular-platelet interaction.

Noninvasive Cardiac Output Measurement in Heart Failure Subjects on Circulatory Support

BACKGROUND: Pulmonary artery catheter (PAC) thermodilution is commonly used in the perioperative cardiac surgical intensive care unit for measurement and management of central hemodynamics despite questions about effectiveness, difficulty of use, and safety. USCOM is a noninvasive continuous wave Doppler device for direct measurement of cardiac output (CO) and is an alternative to PAC. USCOM validation has predominantly been in the cardiac surgical intensive care unit against PAC, despite the recognized limitations in reliability of the method. We compared USCOM CO measurements with the CardioWest, an orthotopic total artificial heart (TAH), in heart failure (HF) subjects during controlled interventions. METHOD: CO, stroke volume (SV), and heart rate (HR) were measured in a blinded fashion using the CardioWest and the USCOM device in TAH HF patients. Five-hundred eight paired measures from 18 examinations of seven subjects were acquired as flow was varied by the CardioWest controller. Bland-Altman analysis was used to compare agreement. RESULTS: Mean values and standard deviations (±sd) for CO, SV, and HR by CardioWest and USCOM were 7.33 ± 0.46 and 7.34 ± 0.51 L/min, 56.2 ± 3.8 and 56.6 ± 3.8 mL, and 131 ± 3 and 130 ± 4 bpm, respectively. CO ranged from 5.2 to 9.3 L/min. The mean differences between methods for CO, SV, and HR were −0.01 ± 0.23 L/min, −0.34 ± 1.97 mL, and 0.9 ± 2.3 bpm, respectively, with mean percentage differences of −0.3%, −0.6%, and 0.7%. The percentage limits of agreement for CO, SV, and HR were 6.4%, 7.1%, and 3.6%. DISCUSSION: USCOM is a feasible and accurate method for noninvasive measurement and monitoring of CO in TAH HF patients and may have a wider application in diagnosis and management of cardiovascular disease.

Continuous cardiac output measurements

C ONTINUOUS cardiac output (CCO) measurement first became clinically available in 1991.’ Now known as the VigilanceiIntellicath Continuous Cardiac Output System (Baxter Edwards Critical Care, Irvine, CA), it uses a specialized pulmonary artery catheter that is capable of safely measuring a continuous time-averaged cardiac output.2 This system has overcome the problems associated with earlier designs and its performance has been summarized in several publications.3-h Whereas the most recent information confirms the accuracy of CC0,‘m9 these authors have often been asked if this technology was really useful, and could its use in light of its higher cost be justified. A case is described here where the use of the CC0 system had a direct impact on the postoperative care of a cardiac surgery patient.

Changes in Left Ventricular Performance Related to Perioperative Myocardial Infarction in Coronary Artery Bypass Graft Surgery

Strict electrocardiographic, enzymatic, scintigraphic, and hemodynamic criteria for perioperative myocardial infarction (MI) were defined and related to serial assessments of left ventricular performance during rest and exercise in patients seen early and late after coronary artery bypass graft operation. Global left ventricular performance was determined by radionuclide ventriculography from which changes in the pattern of serial postoperative ejection fractions (EF) were obtained. Patients were divided into two groups based on the presence or absence of perioperative MI, and were matched in pairs on the basis of preoperative EF and extent as well as location of coronary artery obstructions. The results indicate that neither short- nor long-term depression in resting EF occurred subsequent to perioperative MI. However, an exercise-related increase in EF eight months postoperatively was depressed in patients who had perioperative MI compared with those who did not. Patients with new Q waves and abnormal postoperative elevation in serum levels of the myocardial isoenzyme of creatine kinase (CK-MB) had a greater early decrease in EF compared with patients without evidence of perioperative MI. However, seven days after operation, the EF in both groups returned to preoperative levels. Patients with abnormal technetium 99m-pyrophosphate scintigrams had changes in perioperative EF similar to those in patients without MI. The presence of low cardiac output syndrome immediately after operation was associated with immediate and short-term decreases in EF, which were not seen in any of the other patient subgroups.

Nonrandomized Matched Pair Analysis of Intermittent Ischemic Arrest versus Potassium Crystalloid Cardioplegia during Myocardial Revascularization

The quest for the ideal method of myocardial preservation during coronary artery bypass graft (CABG) surgery continues at a rapid pace. Nevertheless, in the present clinical practice of cardiac surgery, the choice is chiefly between hypothermic intermittent ischemic arrest and hypothermic potassium cardioplegia. This study applies newer technics in radionuclear cardiology, as well as more conventional enzymatic, electrocardiographic, and hemodynamic determinations, to the evaluation of the effectiveness of the previously mentioned modes of myocardial protection. Serial assessments are made preoperatively as well as during the first ten days postoperatively. We find that the perioperative incidence of myocardial damage and changes in left ventricular performance are almost identical using either method in patients with relatively normal preoperative left ventricular performance who do not have severe preoperative refractory ischemia or necrosis.

Microbial contamination of blood conservation devices during routine use in the critical care setting : Results of a prospective, randomized trial

OBJECTIVES To compare microbial contamination of two different blood conservation devices; to determine if there was an association between contamination of the blood conservation devices and clinical infections; to determine if there was a significant user preference for either of the two devices. DESIGN Prospective, randomized trial. SETTING Medical, neurosurgical, and spinal cord intensive care units of an urban, university hospital. PATIENTS Forty patients who required clinically indicated intrafierial catheters placed at new sites. INTERVENTIONS The two most widely available blood conservation devices at the time of the study (Venous Arterial blood Management Protection system [VAMP], Baxter Edwards Critical-Care, Irvine, CA; and Safe Draw, Ohmeda, Madison, WI) were chosen for comparison. After the normal 48 to 72 hrs of device use, the blood conservation systems were removed and semi-quantitative and quantitative cultures were taken from comparable sites of the two devices. Positive cultures from the patients were recorded and correlated with cultures obtained from the devices. In order to assess preference for either device, a survey tool was administered to the nursing staff who participated in the study. MEASUREMENTS AND MAIN RESULTS Quantitative cultures from all sites cultured in both groups demonstrated mean colony counts of < 10(3) colony-forming units (cfu)/mL. There were no statistically significant differences in the colony counts at any of the sites compared between the two groups. There were no statistically significant relationships between positive cultures and patient age, gender, duration of device utilization, frequency of device entry, or the intensive care unit in which the study was conducted. In no circumstance did positive cultures from any of the blood conservation devices correlate with positive culture results from any sites of clinical infection. The clinical survey demonstrated a statistically significant preference for the VAMP system, which persisted despite increased experience with the Safe Draw system. CONCLUSIONS The levels of microbial contamination noted in these devices were not consistent with clinical infection (defined as 10(3) cfu/mL on quantitative cultures). There was no significant difference in degree or pattern of contamination between the two devices. When utilized and changed according to the Centers for Disease Control guidelines, blood conservation devices are not harbors of infection in the critical care setting. Blood conservation devices can be used as part of a comprehensive blood conservation program in the critical care setting without undue concern for exacerbating infectious processes.

Anesthetic management of a patient with a single ventricle and modified Fontan procedure

ECENT ADVANCES in surgical techniques and anesR thetic management have made possible the partial or complete correction of many congenital cardiac anomalies. During the past decade, procedures based on the concepts described by Fontan’ and by Kruetzer2 have been developed for the physiologic correction of tricuspid atresia and these have been modified and applied to other complex congenital anomalies. In the Fontan procedure systemic venous blood is directed from the right atrium into the lungs via the pulmonary arteries and pulmonary venous blood into the arterial circulation, thereby resulting in a physiologic correction of the congenital defect. Closure of the atria1 septal defect prevents mixing of oxygenated with deoxygenated blood. Patients treated with the Fontan procedure may attain adulthood and become candidates for noncardiac operations that necessitate anesthesia. The anesthetic management and rationale for this approach in a patient with a univentricular heart who had a modified Fontan procedure and who was scheduled for reduction mammoplasties are reported.