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Biomedical subjects

R J McCarthy

Publications and source records attributed to R J McCarthy.

At least 19 recordsLinked to original sources
PubMed1992

Oxygen consumption and mixed venous oxygen saturation monitoring during orthotopic liver transplantation.

Mixed venous oxygen saturation (SvO2) monitoring has been advocated for some critically ill patients. Patients with end-stage hepatic failure have oxygen consumption rates that are lower than normal. Using the Fick equation, oxygen consumption may be calculated if mixed venous and arterial oxygen tensions (and saturations), hemoglobin, and cardiac output are determined simultaneously. This report describes a unique pattern of changes in SvO2 and oxygen consumption in 7 patients undergoing liver transplantation. A previous study correlated plasma carbohydrate (glucose) levels with early hepatic graft survival. After induction, the 7 patients reported here had low oxygen consumption and high SvO2 values. The oxygen consumption rates decreased to the lowest point during the anhepatic phase and rose above baseline by the end of the case. The SvO2 and oxygen consumption data reported here follow the presence of presumed hepatic metabolic activity (increased CO2 and ionized calcium). Further research must be completed to determine whether these measurements indicate early hepatic nonfunction.

Adult↗
PubMed1992

Autologous blood donation: hemodynamics in a high-risk patient population.

Transfusion practices have changed dramatically in recent years as a result of the acquired immune deficiency syndrome crisis. The use of preoperative donation of autologous blood units has gained popularity. Healthy individuals tolerate phlebotomy well, experiencing a 2- to 5-percent incidence of vasovagal reactions. However, no systematic study of hemodynamic function during phlebotomy exists for patients who have major cardiovascular or multiple organ disease (high-risk patients). The following protocol examines blood pressure, heart rate, cardiac output, lead II electrocardiogram, and pulse oximetry in 123 patients donating a total of 224 units of blood in a new high-risk autologous blood donation program that was conducted in a postanesthesia care unit over the past 18 months. Changes in hemodynamic variables during phlebotomy were consistent with mild volume depletion; the changes did not result in overall differences in the courses of the groups. Significant numbers of patients exhibited systolic or diastolic hypotension, dysrhythmias, syncope, and tachycardia. Because tolerance for hypotension (vasovagal reactions) is decreased in patients with coronary artery disease, appropriate monitoring may be warranted to maximize the safety of elective phlebotomy. Further study is required to stratify risks and to determine which hemodynamic variables are predictive of adverse events.

Adolescent↗
PubMed1992

The Hopkins Competency Assessment Test: a brief method for evaluating patients' capacity to give informed consent.

The Hopkins Competency Assessment Test (HCAT), a brief instrument for evaluating the competency of patients to give informed consent or write advance directives, consists of a short essay and a questionnaire for determining patients' understanding of the essay. In a study to validate the instrument, 41 medical and psychiatric inpatients answered the questionnaire after reading the essay while bearing it read aloud. A forensic psychiatrist who was blind to the HCAT scores later examined the patients for competency. A subject's number of correct answers to the HCAT questionnaire was an accurate indicator of clinical competency as assessed by the psychiatrist. The results suggest that the HCAT is a useful tool for rapidly screening patients for competency to make treatment decisions.

Adult↗
PubMed1992

Morbidity and duration of ICU stay after cardiac surgery. A model for preoperative risk assessment.

Although risk factors for mortality after cardiac surgery have been identified, there is no widely applicable method for readily determining risk of postoperative morbidity based on preoperative severity of illness. The goal of this study was to develop a model for stratifying the risk of serious morbidity after adult cardiac surgery using readily available and objective clinical data. After univariate analysis of risk factors in 3,156 operations, 11 variables were identified as important predictors by logistic regression (LR) analysis and used to construct an additive model to calculate the probability of serious morbidity. Reliable correlation was found between a simplified additive model for clinical use and the LR model. The clinical and logistic models were then tested prospectively in 394 patients and demonstrated a pattern of increasing morbidity with ascending scores similar to that predicted by the reference group. Increasing clinical risk score was also associated with a greater frequency of individual complications as well as prolongation of ICU stay. This study demonstrates that it is feasible to design a simple method to stratify the risk of serious morbidity after adult cardiac surgery. With further prospective multicenter refinement and testing, such a model is likely to be useful for adjusting severity of illness when reporting outcome statistics as well as planning resource utilization.

Aged↗
PubMed1992

Differential effects of advanced age on neurologic and cardiac risks of coronary artery operations.

Two thousand patients undergoing coronary artery bypass grafting with cardiopulmonary bypass were prospectively studied to compare the influence of age on the incidence of neurologic, cardiac, and other complications. Postoperative neurologic events were found in 56 (2.8%) patients, with an incidence in patients > or = 75 years (8.9%) more than twice that of patients 65 to 74 (3.6%) and nine times larger than in patients < 65 (0.9%). Cardiac complications did not differ between age groups except for low cardiac output state, which occurred 1.7 times more frequently in patients > or = 75 years compared with those < 65. Patients with postoperative neurologic events had a ninefold increase in mortality--35.7% versus 4.0%. Logistic regression analysis demonstrate the most important predictors of a postoperative neurologic event to be age, preoperative neurologic abnormality, recent myocardial infarction, and duration of cardiopulmonary bypass. The risk of neurologic complications increases disproportionately to the risk of cardiac complications in the elderly undergoing coronary artery bypass grafting with cardiopulmonary bypass. Despite neurologic improvement (32 of 56 patients), a postoperative neurologic event was second only to low cardiac output state as the postoperative complication most highly associated with in-hospital death. These results are important for decisions regarding selection of candidates for coronary artery bypass grafting and for prediction of surgical outcome.

Age Factors↗
PubMed1991

Efficacy of ephedrine in the prevention of postoperative nausea and vomiting.

Although reported in the aerospace literature and anecdotally by anesthesiologists, the putative antiemetic effect of ephedrine remains unquantitated. We therefore prospectively studied ephedrine as an antiemetic agent in the perioperative setting in 97 patients undergoing general anesthesia for outpatient gynecologic laparoscopy. Patients were assigned in a double-blind randomized fashion to receive a standardized general anesthetic followed by an intramuscular dose of either ephedrine (0.5 mg/kg), droperidol (0.04 mg/kg), or saline before the conclusion of surgery. Nausea, retching, or vomiting, as well as the degree of sedation and discharge times, were assessed in the recovery room and for 24 h postoperatively. Ephedrine was found to have a significantly antiemetic effect (P less than 0.05) when compared with placebo and an antiemetic effect similar to that of droperidol. Sedation scores were also significantly less in the ephedrine group than in both placebo and droperidol groups. Finally, variations in mean arterial blood pressure among the three groups were not statistically significant. We conclude that ephedrine is an effective antiemetic agent with minimal sedative side effects in patients undergoing outpatient laparoscopy.

Adult↗
PubMed1991

Effects of epidural anesthesia and analgesia on coagulation and outcome after major vascular surgery.

To examine the interaction of epidural anesthesia, coagulation status, and outcome after lower extremity revascularization, 80 patients with atherosclerotic vascular disease were prospectively randomized to receive general anesthesia combined with postoperative epidural analgesia (GEN-EPI) or general anesthesia with on-demand narcotic analgesia (GEN). Demographics did not differ between groups except that the GEN-EPI group had a higher incidence of diabetes mellitus and of previous myocardial infarction. Coagulation status was monitored using thromboelastography. An additional 40 randomly selected patients without atherosclerotic vascular disease undergoing noncardiovascular procedures served as controls for coagulation status. Vascular surgical patients were hypercoagulable compared with control patients before operation and on the first postoperative day. Postoperatively, this hypercoagulability was attenuated in the GEN-EPI group and was associated with a lower incidence of thrombotic events (peripheral arterial graft coronary artery or deep vein thromboses). The rates of cardiovascular, infectious, and overall postoperative complications, as well as duration of intensive care unit stay, were significantly reduced in the GEN-EPI group. Stepwise logistic regression demonstrated that the only significant predictors of postoperative cardiovascular complications were preoperative congestive heart failure and general anesthesia without epidural analgesia. We conclude that in patients with atherosclerotic vascular disease undergoing arterial reconstructive surgery (a) thromboelastographic evidence of increased platelet-fibrinogen interaction is associated with early postoperative thrombotic events, and (b) epidural anesthesia and analgesia is associated with beneficial effects on coagulation status and postoperative outcome compared with intermittent on-demand opioid analgesia.

Aged↗
PubMed1990

Sufentanil-midazolam anesthesia for coronary artery surgery.

The combination of benzodiazepines and high-dose narcotics has been reported to produce hypotension in patients undergoing coronary artery surgery. This study was performed to evaluate the cardiovascular effects of lower doses of the narcotic sufentanil administered with the benzodiazepine midazolam. Thirty adult patients with good ventricular function undergoing elective coronary revascularization received sufentanil, 2.5 micrograms/kg, and midazolam, 0.1 mg/kg, followed by infusions of sufentanil, 0.7 to 1.5 micrograms/kg/h, and midazolam, 0.07 to 0.15 mg/kg/h. Overall, stable hemodynamics were achieved before and after cardiopulmonary bypass (CPB). Patients who were not receiving preoperative beta-adrenergic blockade (n = 15) had increases from baseline heart rate and rate-pressure product after sternotomy, during aortic dissection, and after CPB that were not clinically significant. Five patients developed hypertension (increases greater than 20% over the baseline value), which was controlled with additional sufentanil or a vasodilator. Hypertension requiring vasodilator therapy did not occur in patients taking beta-adrenergic blockers. Blood pressure decreases exceeding 20% of the baseline value did not occur. Two of 15 patients receiving beta-blockers, versus 3 of 15 not receiving beta-blockers, developed ischemic electrocardiographic changes before CPB (NS); one of these patients without beta-blockade had a postoperative myocardial infarction. The results of this study show that the infusion of low doses of sufentanil with midazolam provides a hemodynamically safe and stable anesthetic for coronary artery surgery and avoids the hypotension seen when a high-dose narcotic is combined with a benzodiazepine.

Adrenergic beta-Antagonists↗
PubMed1990

Comparison of anesthetic techniques in patients undergoing heart valve replacement.

A prospective study of 324 adult patients undergoing operations requiring cardiopulmonary bypass for heart valve replacement was undertaken to determine the effect of anesthetic technique on outcome. Patients received one of three primary techniques: fentanyl (40-100 micrograms/kg), sufentanil (4-8 micrograms/kg), or diazepam (0.4-1 mg/kg) with ketamine (3-6 mg/kg). Supplemental inhalation anesthesia with enflurane, halothane, or isoflurane was used in 43.8% of cases. Patients in these anesthetic groupings had similar perioperative demographic and risk classifications. Although there were differences in the requirements for vasopressors postoperatively among the intravenous anesthetic agents, neither mortality rates, length of ICU stay, nor incidence of postoperative heart failure showed the advantage of any intravenous or inhalational agent. There were also no significant differences in the incidences of serious pulmonary, renal, or neurologic morbidity among primary anesthetic techniques nor among supplemental inhalation agents. Multivariate discriminant analysis of these data suggests that many factors are significantly more important than anesthetic technique as determinants of outcome after heart valve replacement.

Analysis of Variance↗
PubMed1990

Comparative effects of esmolol and verapamil in a model of a supraventricular tachydysrhythmia.

Supraventricular tachydysrhythmias are a commonly encountered clinical problem after cardiothoracic surgery. Current choices for acute drug therapy of these dysrhythmias include intravenous verapamil as well as esmolol, but no data yet exist comparing the relative negative dromotropic (atrioventricular [A-V] nodal blocking) and negative inotropic effects of these agents. The purpose of this study was to compare the effects of esmolol with those of verapamil on systemic hemodynamics, coronary blood flow, and cardiac contractility at doses that produce a similar ventricular response rate in an animal model of a supraventricular tachydysrhythmia. Rapid electrical stimulation (800 impulses/min) of the left atrium in 14 dogs resulted in a rapid and irregularly irregular ventricular rhythm. Esmolol or verapamil were administered by bolus and then infusion to incrementally slow the average ventricular rate. Regional myocardial contractility was measured using the end-systolic pressure-length relationship (Ees). At drug doses that produced similar decreases in ventricular rate, esmolol produced a greater decrease in contractility (Ees: 284 +/- 46 to 40 +/- 22 mmHg/mm, LV dp/dt: 2,400 +/- 450 to 1,360 +/- 450 mmHg/sec) compared with that following verapamil (Ees: 297 +/- 57 to 116 +/- 25 mmHg/mm, LV dp/dt: 2,040 +/- 580 to 1,950 +/- 520 mmHg/sec). This was accompanied by a modest decrease in cardiac output in the esmolol group (2,800 +/- 940 to 2,290 +/- 730 ml/min) compared with an unchanged cardiac output as ventricular rate slowed in verapamil-treated animals. Stroke volume increased significantly in the verapamil-treated animals (10.9 +/- 4.0 to 18.5 +/- 4.6 ml), but remained unchanged following esmolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1989

Effect of helium-neon and infrared laser irradiation on wound healing in rabbits.

We examined the biostimulating effects of helium-neon laser radiation (HeNe; 632.8 nm), pulsed infrared laser radiation (IR; 904 nm), and the two combined on skin wound healing in New Zealand white rabbits. Seventy-two rabbits received either 1) no exposure, 2) 1.65 J/cm2 HeNe, 3) 8.25 J/cm2 pulsed IR, or 4) both HeNe and IR together to one of two dorsal full-thickness skin wounds, daily, for 21 days. Wound areas were measured photographically at periodic intervals. Tissue samples were analyzed for tensile strength, and histology was done to measure epidermal thickness and cross-sectional collagen area. Significant differences were found in the tensile strength of all laser-treated groups (both the irradiated and nonirradiated lesion) compared to group 1. No differences were found in the rate of wound healing or collagen area. Epidermal growth was greater in the HeNe-lased area compared to unexposed tissue, but the difference was not significant. Thus, laser irradiation at 632.8 nm and 904 nm alone or in combination increased tensile strength during wound healing and may have released tissue factors into the systemic circulation that increased tensile strength on the opposite side as well.

Animals↗
PubMed1989

The impact of liver transplant programs on anesthesia personnel and services.

Liver transplantation procedures are being performed at an increasing number of hospitals throughout the United States. These procedures are challenging because of hemodynamic, metabolic, renal, and coagulation dysfunctions and may require prolonged periods of time for completion. Anesthesia departments are developing or managing teams of personnel to perform liver transplants. A survey was sent to directors of liver transplant anesthesia teams to investigate how teams were structured, compensated, and the impact of participation upon personnel involved. Thirty-nine centers were surveyed and 31 responded. The results showed an arithmetic doubling of cases for each of the last six years, most being performed at large medical centers (more than 759 beds) with populations served of 2 million or more. Cases were reported to average 13 hours in length and required a mean of five anesthesia personnel to complete. Compensation methods for work on a liver transplant team were variable; however, CRNAs and technicians received monetary reimbursement more frequently than physicians. Emotional responses of personnel were equally divided between favorable and unfavorable responses. Discriminate analysis showed that positive personnel attitudes were most closely tied to the presence of a protocol for breaks, call schedules, compensation, and the frequency of performing these cases. However, most protocols for personnel management were instituted in response to dissatisfaction. As the number of transplants per year increases, departments will need effective plans for personnel management to maximize departmental resources, increase research interest, and maintain personnel enthusiasm.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Does choice of anesthetic agent significantly affect outcome after coronary artery surgery?

A prospective study of 1094 consecutive adult patients undergoing coronary revascularization was undertaken to determine the effect of anesthetic technique on outcome. Patients received one of five primary techniques: high-dose fentanyl (greater than 50 micrograms/kg), moderate-dose fentanyl (less than 50 micrograms/kg), sufentanil (3-8 micrograms/kg), diazepam (0.4-1 mg/kg) with ketamine (3-6 mg/kg) or halothane (0.5-2.5% inspired concentration after thiopental induction). Supplemental inhalation anesthesia (enflurane, halothane, or isoflurane) was used in 60% of cases where the primary technique was intravenous based. Patients in the above anesthetic groupings had similar perioperative demographic and risk classifications. The overall incidence of postoperative myocardial infarction, postoperative low cardiac output state, and in-hospital death were 4.1, 5.6, and 3.1%, respectively. There were no significant differences in the incidence of these occurrences or in the incidence of serious pulmonary, renal, or neurologic morbidity or length of ICU stay among primary anesthetic techniques nor among supplemental inhalation agent groups. Multivariate discriminant analysis of this data suggests that a multitude of factors are significantly more important than anesthetic technique as determinants of outcome after coronary artery surgery.

Adult↗
PubMed1989

Effect of pulmonary artery catheterization on outcome in patients undergoing coronary artery surgery.

Previous studies have suggested that low-risk cardiac surgical patients may be safely managed without pulmonary artery catheterization (PAC). However, no prospective studies have determined whether PAC improves outcome in higher risk patients compared with that following central venous pressure (CVP) monitoring alone. The authors prospectively examined the incidence of and factors related to perioperative morbidity and mortality in 1094 consecutive patients undergoing coronary artery surgery managed with elective PAC (n = 537) or with CVP (n = 557). Perioperative risk factors and demographics that predict morbidity and mortality after cardiac surgery were used to quantify risk classification. Outcome was judged by length of ICU stay, occurrence of postoperative myocardial infarction, in-hospital death, major hemodynamic aberrations, and significant noncardiac systemic complications. No significant differences in any outcome variables were noted in any group of patients with similar quantitative risk classification managed with or without PAC, including those in the highest risk class. In addition, there were no significant differences in outcome among the 39 patients who would have been managed with CVP monitoring only, but who subsequently developed a clinical need for PAC based on the occurrence of serious hemodynamic events compared to patients who had PAC performed electively. This study suggests that PAC does not play a major role in influencing outcome after cardiac surgery, that even high-risk cardiac surgical patients may be safely managed without routine PAC, and that delaying PAC until a clinical need develops does not significantly alter outcome, but may have an important impact on cost savings.

Aged↗
PubMed1989

Comparison of viscoelastic measures of coagulation after cardiopulmonary bypass.

Postoperative hemorrhage remains a major cause of morbidity after cardiopulmonary bypass (CPB). Treatment remains empiric because of the need for immediate correction and the lack of availability of rapid intraoperative coagulation monitoring (except for ACT) at most institutions. Thrombelastography (TEG) and Sonoclot analysis (SCT) are measures of viscoelastic properties of blood which allow rapid intraoperative evaluation of coagulation factor and platelet activity as well as overall clot integrity from a single blood sample. Routine coagulation tests (RCT) including activated clotting time (ACT), prothrombin time (PT), partial thromboplastin time (PTT), fibrinogen level (FIB), and platelet count (PLT) were determined and compared to TEG and SCT to assess which best predicted clinical hemostasis after CPB. Forty-two patients prospectively felt to be at high risk for excessive post-CPB bleeding had blood obtained for RCT, TEG, and SCT analysis before systemic heparinization and 30 min after protamine administration. Nine of 42 patients had excessive chest tube drainage, but no reoperations were required. After CPB, mean values for RCT were normal, but there were abnormalities in TEG and SCT parameters that reflect platelet-fibrin interaction. Both TEG and SCT were 100% accurate in predicting bleeding in these nine patients and, overall, both tests were significantly better predictors of postoperative hemorrhage than RCT. We conclude that viscoelastic determinants of clot strength may be abnormal after CPB and that SCT and TEG are, therefore, more useful than RCT for the detection and management of coagulation defects associated with CPB.

Adult↗
PubMed1988

The incidence of venous air embolism during total hip arthroplasty.

Venous air embolism has been reported to occur during total hip arthroplasty. The incidence of venous air embolism, however, has not been previously studied in a large series using Doppler ultrasound and mass spectrometry. Seventy patients undergoing total hip arthroplasty were monitored for venous air embolism with precordial Doppler ultrasound, central venous catheter, end-tidal N2 and CO2 (mass spectrometry), and arterial blood gases (ABG). Changes in the monitored variables consistent with venous air embolism were noted in 57% by Doppler ultrasound, 9% by mass spectrometry, 4% by central venous catheter and 3% of the cases by ABG. A total of 77 Doppler ultrasound events were detected in 40 of the 70 patients studied. Hemodynamic changes consisting of either hypotension, defined as a greater than or equal to 20% decrease in mean arterial pressure (MAP), or cardiac dysrhythmia occurred during 43% of these events. The Doppler ultrasound was the only monitor that detected all cases of venous air embolism with concomitant hemodynamic changes. Air was aspirated from the central venous catheter during 10% of the detections of venous air embolism by Doppler ultrasound. Venous air embolism in total hip arthroplasty is a common event and may be responsible for hemodynamic changes previously ascribed to the use of methylmethacrylate cement. Routine monitoring with Doppler ultrasound appears warranted. The routine use of central venous catheterization may also be warranted.

Blood Gas Monitoring, Transcutaneous↗