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Biomedical subjects

J M Leung

Publications and source records attributed to J M Leung.

At least 19 recordsLinked to original sources
PubMed2006

Pilot clinical trial of gabapentin to decrease postoperative delirium in older patients.

In this randomized pilot clinical trial, the authors tested the hypothesis that using gabapentin as an add-on agent in the treatment of postoperative pain reduces the occurrence of postoperative delirium. Postoperative delirium occurred in 5/12 patients (42%) who received placebo vs 0/9 patients who received gabapentin, p = 0.045. The reduction in delirium appears to be secondary to the opioid-sparing effect of gabapentin.

Amines↗
PubMed2006

Nitrous oxide does not change the incidence of postoperative delirium or cognitive decline in elderly surgical patients.

BACKGROUND: Postoperative delirium and cognitive decline are common in elderly surgical patients after non-cardiac surgery. Despite this prevalence and clinical importance, no specific aetiological factor has been identified for postoperative delirium and cognitive decline. In experimental setting in a rat model, nitrous oxide (N(2)O) produces neurotoxic effect at high concentrations and in an age-dependent manner. Whether this neurotoxic response may be observed clinically has not been previously determined. We hypothesized that in the elderly patients undergoing non-cardiac surgery, exposure to N(2)O resulted in an increased incidence of postoperative delirium than would be expected for patients not receiving N(2)O. METHODS: Patients who were >or=65 yr of age, undergoing non-cardiac surgery and requiring general anaesthesia were randomized to receive an inhalational agent and either N(2)O with oxygen or oxygen alone. A structured interview was conducted before operation and for the first two postoperative days to determine the presence of delirium using the Confusion Assessment Method. RESULTS: A total of 228 patients were studied with a mean (range) age of 73.9 (65-95) yr. After operation, 43.8% of patients developed delirium. By multivariate logistic regression, age [odds ratio (OR) 1.07; 95% confidence interval (CI) 1.02-1.26], dependence on performing one or more independent activities of daily living (OR 1.54; 95% CI 1.01-2.35), use of patient-controlled analgesia for postoperative pain control (OR 3.75; 95% CI 1.27-11.01) and postoperative use of benzodiazepine (OR 2.29; 95% CI 1.21-4.36) were independently associated with an increased risk for postoperative delirium. In contrast, the use of N(2)O had no association with postoperative delirium. CONCLUSIONS: Exposure to N(2)O resulted in an equal incidence of postoperative delirium when compared with no exposure to N(2)O.

Activities of Daily Living↗
PubMed2001

Relative importance of preoperative health status versus intraoperative factors in predicting postoperative adverse outcomes in geriatric surgical patients.

OBJECTIVES: To determine the prevalence and predictors of adverse postoperative outcomes in older surgical patients undergoing noncardiac surgery. DESIGN: Prospective cohort study of consecutive patients undergoing noncardiac surgery in 1997. SETTING: A medical school-affiliated teaching community hospital. PARTICIPANTS: Patients age 70 and older undergoing noncardiac surgery. Patients presenting for surgery requiring only local anesthesia or monitored anesthesia care were excluded. MEASUREMENTS: Potential pre- and intra-operative risk factors were measured and evaluated for their association with the occurrence of predefined in-hospital postoperative adverse outcomes. Univariate predictors of postoperative outcomes were first measured using the chi-square or Fisher's exact tests followed by multivariate logistic regression. Odds ratios (OR) with 95% confidence interval (CI), and two-sided P-values were reported. RESULTS: Five hundred forty-four consecutive patients were studied. Overall, 21% of patients developed one or more postoperative adverse outcomes and 3.7% died during the in-hospital postoperative period. Of all the adverse outcomes, cardiovascular complications (10.3%) were the leading cause of morbidity, followed by neurological (7.7%) and pulmonary complications (5.5%). By multivariate logistic regression analysis, American Society of Anesthesiologists (ASA) classification (OR = 2.7, CI = 1.6-4.4), emergency surgery (OR = 2.0, CI = 1.1-3.4), and intraoperative tachycardia (OR = 3.8, CI = 1.9-7.6) were the most important predictors of postoperative adverse outcomes. Of all the preoperative physical symptoms and signs, decreased functional status (OR = 3.0, CI = 1.4-6.4) and clinical signs of congestive heart failure (OR = 2.1, CI = 1.1-5.1) were the two most important predictors of postoperative adverse neurological and cardiac outcomes, respectively. The median hospital stay was 4 days. The patients who developed postoperative adverse outcomes had significantly longer median hospital stays (9 days) than those without complications (3 days), (P < .0001). CONCLUSION: Our study demonstrates that the postoperative mortality rate in geriatric surgical patients undergoing noncardiac surgery is low. Despite the prevalence of preoperative chronic medical conditions, most patients do well postoperatively. The ASA classification (a reflection of the severity of preoperative comorbidities), emergency surgery, and intraoperative tachycardia increase the odds of developing any postoperative adverse events. Future studies aimed at modifying some of the potentially reversible risk factors, such as preoperative heart function and intraoperative heart rate are warranted.

Activities of Daily Living↗
PubMed2001

The prevalence and predictive value of abnormal preoperative laboratory tests in elderly surgical patients.

UNLABELLED: Because data to determine which preoperative laboratory tests are important in elderly surgical patients are limited, we performed a prospective cohort study to evaluate the prevalence and predictive value of abnormal preoperative laboratory tests in consecutive patients > or =70 yr old who were undergoing noncardiac surgery. Patients presenting for surgery requiring only local anesthesia or monitored anesthesia care were excluded. Preoperative risk factors and laboratory test results were measured and evaluated for their association with the occurrence of predefined in-hospital postoperative adverse outcomes. In 544 patients, the prevalence of preoperative electrolytes and platelet count abnormalities (<115 x10(9)/L) was small (0.5%-5%), and abnormal creatinine (>1.5 mg/dL), hemoglobin (<10 g/dL), and glucose (>200 mg/dL) values were 12%, 10%, and 7%, respectively. Univariate predictors for adverse outcome of abnormal sodium and creatinine were not as predictive as ASA classification and surgical risk. By multivariate logistic regression, only ASA classification (>II) (odds ratio [OR], 2.55; 95% confidence interval [CI], 1.56-4.19; P < 0.001) and surgical risk (OR, 3.48; 95% CI, 2.31-5.23; P < 0.001) were significant independent predictors of postoperative adverse outcomes. The prevalence of abnormal preoperative electrolyte values and thrombocytopenia was small and had low predictive values. Although more prevalent, abnormal hemoglobin, creatinine, and glucose values were also not predictive of postoperative adverse outcomes. Routine preoperative testing for hemoglobin, creatinine, glucose, and electrolytes on the basis of age alone may not be indicated in geriatric patients. Rather, selective laboratory testing, as indicated by history and physical examination, which will determine patient's comorbidities and surgical risk, seems to be indicated. IMPLICATIONS: The prevalence of abnormal preoperative electrolyte values and thrombocytopenia was small and had low predictive values. Although more prevalent, abnormal hemoglobin, creatinine, and glucose values were also not predictive of postoperative adverse outcomes. Routine preoperative testing for hemoglobin, creatinine, glucose, and electrolytes on the basis of age alone may not be indicated in geriatric patients. Rather, selective laboratory testing, as indicated by history and physical examination, which will determine patient's comorbidities and surgical risk, seems to be indicated.

Aged↗
PubMed2001

The prevalence and predictors of the use of alternative medicine in presurgical patients in five California hospitals.

UNLABELLED: We measured the prevalence and predictors of the use of alternative medicine supplements in surgical patients by way of a self-administered questionnaire in consecutive patients > or = 18 yr old awaiting elective noncardiac surgery at five San Francisco Bay Area Hospitals. A total of 2560 patients completed the study survey (60% response rate). Of these patients, 39.2% admitted to using some form of alternative medicine supplements, of which herbal medicine was the most common type (67.6%). Of those who admitted to taking alternative medicine supplements, 44.4% did not consult with their primary physicians, and 56.4% did not inform the anesthesiologists before surgery regarding their use of these products; 53% of the patients ceased the use of these products before surgery. Multivariate logistic regression analysis revealed the following variables to be associated with the preoperative use of herbal medicine: female sex (odds radio [OR] 1.42, confidence interval [CI] 1.17-1.72), age 35-49 yr (OR 1.25, CI 1.02-1.53), higher income levels (OR 1.85, CI 1.50-2.27), Caucasian race (OR 1.34, CI 1.07-1.67), higher level of education (OR 1.35, CI 1.10-1.65), problems with sleep (OR 1.32, CI 1.05-1.66), problems with joints or back (OR 1.27, CI 1.04-1.56), allergies (OR 1.48, CI 1.21-1.82), problems with addiction (OR 1.90, CI 1.25-2.89), and a history of general surgery (OR 1.25, CI 1.03-1.52). In contrast, diabetes mellitus (OR 0.55, CI 0.36-0.86) and the use of antithrombotic medications (OR 0.57, CI 0.38-0.87) were associated with decreased odds of the use of herbal medicines. We concluded that the use of alternative medicine supplements by surgical patients is prevalent. Documentation of the use of these products is critical to determine the potential of drug or anesthetic interactions in the perioperative period. IMPLICATIONS: The use of alternative medicine supplements by presurgical patients is prevalent. Documentation of the use of these products is critical to determine the potential of drug or anesthetic interactions in the perioperative period.

Adolescent↗
PubMed2000

Electrocardiographic ST-segment changes during acute, severe isovolemic hemodilution in humans.

BACKGROUND: Controversy exists regarding the lowest blood hemoglobin concentration that can be safely tolerated. The authors studied healthy resting humans to test the hypothesis that acute isovolemic reduction of blood hemoglobin concentration to 5 g/dl would produce an imbalance in myocardial oxygen supply and demand, resulting in myocardial ischemia. METHODS: Fifty-five conscious healthy human volunteers were studied. Isovolemic removal of aliquots of blood reduced blood hemoglobin concentration from 12.8 +/- 1.2 to 5.2 +/- 0.5 g/dl (mean +/- SD). Removed blood was replaced simultaneously with intravenous fluids to maintain constant isovolemia. Hemodynamics and arterial oxygen content (Cao2) were measured before and after removal of each aliquot of blood. Electrocardiographic (ECG) changes were monitored continuously using a Holter ECG recorder for detection of myocardial ischemia. RESULTS: During hemodilution, transient, reversible ST-segment depression developed in three subjects as seen on the electrocardiogram during hemodilution. These changes occurred at hemoglobin concentrations of 5-7 g/dl while the subjects were asymptomatic. Two of three subjects with ECG changes had significantly higher heart rates than those without ECG changes at the same hemoglobin concentrations. When evaluating the entire study period, the subjects who had ECG ST-segment changes had significantly higher maximum heart rates than those without ECG changes, despite having similar baseline values. CONCLUSION: With acute reduction of hemoglobin concentration to 5 g/dl, ECG ST-segment changes developed in 3 of 55 healthy conscious adults and were suggestive of, but not conclusive for, myocardial ischemia. The higher heart rates that developed during hemodilution may have contributed to the development of an imbalance between myocardial supply and demand resulting in ECG evidence of myocardial ischemia. However, these ECG changes appear to be benign because they were reversible and not accompanied by symptoms.

Adult↗
PubMed2000

Predicting adverse postoperative outcomes in patients aged 80 years or older.

OBJECTIVE: The identification of reversible factors that are associated with postoperative morbidity in geriatric surgical patients is critical to improving perioperative outcomes in such patients. Our study aimed to compare the relative importance of intraoperative versus preoperative factors in predicting adverse postoperative outcomes in geriatric patients. DESIGN: Retrospective cohort study of consecutive patients undergoing noncardiac surgery in 1995. SETTING: Two University of California, San Francisco, teaching hospitals--Moffitt/Long and Mount Zion medical centers. PARTICIPANTS: All men and women 80 years of age or older undergoing noncardiac surgery. MEASUREMENTS: Medical records of all patients were reviewed to measure predefined pre- and intraoperative risk factors and postoperative outcomes. Predictors of postoperative outcomes were identified by multivariate logistic regression analyses. RESULTS: Three hundred sixty-seven patients were studied. The most prevalent preoperative risk factors were a history of hypertension and coronary artery, pulmonary, and neurologic diseases. Postoperative in-hospital mortality rate was 4.6%, and 25% of patients developed adverse postoperative outcomes, of which neurological and cardiovascular complications were the leading causes of morbidity (15% and 12%, respectively). By multivariate logistic regression, a history of neurological disease (odds ratio [OR] 4.0, 95% confidence interval [CI] 2.3 - 6.9, P = .0001), congestive heart failure (OR 2.7, 95% CI 1.4 - 5.3, P = .004), and a history of arrhythmia (OR 2.3, 95% CI 1.2 - 4.3, P = .01) increased the odds of adverse postoperative events. The only intraoperative event shown to be predictive of postoperative complications was the use of vasoactive agents (OR 8.0, 95% CI 1.6 - 40.5, P = .009). CONCLUSIONS: In this group of geriatric surgical patients, the overall postoperative in-hospital mortality rate was 4.6%, and 25% of the patients developed adverse postoperative outcomes involving either the neurological, cardiovascular, or pulmonary systems. Intraoperative events appeared to be less important than preoperative comorbidities in predicting adverse postoperative outcomes.

Aged↗
PubMed1999

Effects of dobutamine on hemodynamics and left ventricular performance after cardiopulmonary bypass in cardiac surgical patients.

BACKGROUND: Dobutamine is commonly used to improve ventricular performance after cardiopulmonary bypass. The authors determined the effect of dobutamine on hemodynamics and left ventricular performance immediately after cardiopulmonary bypass in patients undergoing coronary artery bypass graft surgery. METHODS: One hundred patients received sequential 3-min infusions of dobutamine at 0-40 microg x kg(-1) x min(-1) immediately after cardiopulmonary bypass. Ten additional patients who received no dobutamine served as controls. Hemodynamics and left ventricular performance (fractional area change by transesophageal echocardiography, stroke volume index, and thermodilution cardiac index) were measured. Mixed-effects modeling accounted for repeated-measures data and interindividual differences and allowed for potential effects of covariates. RESULTS: Heart rate increased in a dose-dependent manner. The slope of HR versus dobutamine dose was steeper in individuals in whom peak dobutamine dose was not reached compared with that in the remaining individuals; slope decreased 2.71 +/- 0.68% per year of age. Dobutamine affected blood pressure minimally, but slightly decreased pulmonary capillary wedge pressure and central venous pressure. Systemic vascular resistance initially increased with dobutamine 10 microg x kg(-1) x min(-1) and remained constant with larger doses. Dobutamine produced a dose-dependent increase in left ventricular performance, primarily by increasing heart rate, because stroke volume index decreased with dobutamine dose. CONCLUSION: Our results suggest that the response to graded dobutamine infusion in the post-cardiopulmonary bypass period differs from that previously reported. After cardiopulmonary bypass, the dominant mechanism by which dobutamine improves left ventricular performance is by increasing heart rate. Dobutamine affects blood pressure minimally.

Aged↗
PubMed1998

Human cardiovascular and metabolic response to acute, severe isovolemic anemia.

CONTEXT: Although concern over the risks of red blood cell transfusion has resulted in several practice guidelines for transfusion, lack of data regarding the physiological effects of anemia in humans has caused uncertainty regarding the blood hemoglobin (Hb) concentration requiring treatment. OBJECTIVE: To test the hypothesis that acute isovolemic reduction of blood Hb concentration to 50 g/L in healthy resting humans would produce inadequate cardiovascular compensation and result in tissue hypoxia secondary to inadequate oxygen transport. DESIGN: Before and after interventional study. SETTING: Academic tertiary care medical center. PARTICIPANTS: Conscious healthy patients (n =11) prior to anesthesia and surgery and volunteers not undergoing surgery (n=21). INTERVENTIONS: Aliquots of blood (450-900 mL) were removed to reduce blood Hb concentration from 131 (2) g/L to 50 (1) g/L [mean (SE)]. Isovolemia was maintained with 5% human albumin and/or autologous plasma. Cardiovascular parameters, arterial and mixed venous oxygen content, oxyhemoglobin saturation, and arterial blood lactate were measured before and after removal of each aliquot of blood. Electrocardiogram and, in a subset, Holter monitor were monitored continuously. MAIN OUTCOME MEASURES: "Critical" oxygen delivery (TO2) as assessed by oxygen consumption (VO2), plasma lactate concentration, and ST changes on electrocardiogram. RESULTS: Acute, isovolemic reduction of Hb concentration decreased systemic vascular resistance and TO2 and increased heart rate, stroke volume, and cardiac index (each P<.001). We did not find evidence of inadequate oxygenation: VO2 increased slightly from a mean (SD) of 3.07 (0.44) mL of oxygen per kilogram per minute (mL O2 x kg(-1) x min[-1]) to 3.42 (0.54) mL O2 x kg(-1) x min(-1) (P<.001) and plasma lactate concentration did not change (0.81 [0.11] mmol/L to 0.62 [0.19] mmol/L; P=.09). Two subjects developed significant ST changes on Holter monitor: one apparently related to body position or activity, the other to an increase in heart rate (at an Hb concentration of 46-53 g/L); both occurred in young women and resolved without sequelae. CONCLUSIONS: Acute isovolemic reduction of blood Hb concentration to 50 g/L in conscious healthy resting humans does not produce evidence of inadequate systemic TO2, as assessed by lack of change of VO2 and plasma lactate concentration. Analysis of Holter readings suggests that at this Hb concentration in this resting healthy population, myocardial ischemia would occur infrequently.

Adult↗
PubMed1998

Dissociation between haemodynamics and sympathetic activation during anaesthetic induction with desfluranes.

PURPOSE: To compare the simultaneous haemodynamic effects, sympathetic activation and cardiac risks associated with desflurane used in a balanced technique, with those of isoflurane anaesthesia. METHODS: A prospective, randomized, open label study was conducted at a University medical centre. Forty patients undergoing major non-cardiac surgery were randomized to receive either desflurane or isoflurane as the primary anaesthetic agent. After premedication, fentanyl and thiopentone were administered i.v.. Anaesthesia was increased up to 1.0 MACET in O2 via controlled mask ventilation and maintained at 1.0 MAC before tracheal intubation. Maintenance consisted of N2O, O2 and desflurane or isoflurane for 10 min. During the study, HR and arterial BP were continuously measured, as were ECG ST-segments and ventricular dysrhythmias using a 3-channel Holter ECG recorder. Left ventricular global and regional function were measured using precordial echocardiography. Serial plasma catecholamine concentrations were measured. RESULTS: For both groups, HR was maintained without increases over baseline values while systolic BP showed a progressive decrease during induction. Use of beta blockade during induction was higher in the desflurane (7/20 = 35%) than in the isoflurane group (1/20 = 5%), P = 0.04. The plasma norepinephrine concentrations progressively increased in the desflurane group but not in the isoflurane group. Four patients in the desflurane and three in the isoflurane group developed transient worsening of regional function but no change in mean left ventricular ejection fraction area and no ECG ischaemia occurred during anaesthetic induction. CONCLUSIONS: Desflurane differs from isoflurane in that sympathetic stimulation persisted despite blunting of potential hyperdynamic haemodynamic responses by narcotic and beta blockade. However, this sympathetic activation did not appear to increase cardiac risks.

Adrenergic beta-Antagonists↗
PubMed1998

Automated electrocardiograph ST segment trending monitors: accuracy in detecting myocardial ischemia.

UNLABELLED: Continuous automated ST segment trending devices (ST trending monitors) are included in most new operating room electrocardiography (ECG) monitors to facilitate ischemia detection, but their efficacy is not well validated. Therefore, we compared their accuracy with that of Holter ECG recorders in detecting ST segment changes (both analyzed offline) in 94 patients undergoing coronary artery bypass graft surgery. Holter ECG tapes were analyzed using standard criteria for determining ECG ischemic episodes, which were compared with those measured by the ST trending monitors. Overall, 42 ischemic episodes were detected by using the Holter monitor in 30 patients. Of the 42 episodes, 38 (90%) were also detected by the ST trending monitors. Sixteen episodes of ST segment deviation were detected by the ST trending monitors, but not by the Holter. The sensitivity of the three ST trending monitors in detecting ischemia was 75%, 78%, and 60% for the Marquette (Milwaukee, WI), Hewlett Packard (Andover, MA), and Datex (Helsinki, Finland) monitors, respectively, with a specificity of 89%, 71%, and 69% relative to the Holter. Compared with the HP and Datex monitors, the Marquette monitor has the best agreement with the Holter (K 0.64). Conditions in which ST trending monitors may be inaccurate were identified and included the appearance of small R-wave amplitude, drifting baseline, and during periods of conduction abnormalities and pacing. We conclude that ST trending monitors have only moderate sensitivity and specificity (< 75% overall) in accurately detecting ECG ST segment changes compared with Holter ECG recordings. Therefore, sole reliance on ST trending monitors for the detection of myocardial ischemia may be insufficient. IMPLICATIONS: Using Holter recordings as the reference standard for detection of intraoperative ischemia, ST trending monitors were found to have overall sensitivity and specificity of 74% and 73%, respectively. Several conditions contribute to the inaccuracy of ST trend monitoring, and additional modification of their performance is necessary to achieve better agreement with the Holter analysis.

Aged↗
PubMed1996

Transesophageal echocardiography in myocardial revascularization: I. Accuracy of intraoperative real-time interpretation.

Transesophageal echocardiography (TEE) is increasingly used intraoperatively as a monitor of ventricular function and volume. Despite its increasing use, whether data from TEE monitoring can be interpreted accurately on-line in real-time is unknown. We studied the performance of five community-based, full-time cardiac anesthesiologists during 75 surgical procedures in which biplane TEE monitoring was used. Every 10 min intraoperatively, each anesthesiologist evaluated the video cine loop display of echocardiographic images to provide a real-time visual estimate of left ventricular ejection fraction area (EFA) and left ventricular filling at the level of the short axis and to assess regional wall-motion of the short axis and transgastric longitudinal views using a predefined scoring system. The same video images were analyzed quantitatively off-line by two blinded investigators. Intraoperative real-time estimates of EFA correlated moderately with off-line quantification (r = 0.8, P = 0.0001). Of the 662 cine loops analyzed by both off-line and real-time techniques, 386 (55%) were within +/-5% of each other, 495 (75%) were within +/-10% of each other, 561 (85%) were within +/-15% of each other, and 617 (93%) were within +/-20% of each other. The overall sensitivity and specificity of real-time echocardiographic ischemia detection were both 76%. However, there was individual variation among the five anesthesiologists. Recognition of normal and severe regional wall-motion abnormality, such as akinesis, had more concordance between real-time and off-line analysis, 93% and 79%, respectively, than recognition of mild regional wall-motion abnormalities. Anesthesiologists can estimate EFA in real-time to within +/-10% of off-line values in 75% of all cases. Real-time identification of normal regional function is more accurate than identification of abnormal function, i.e., there is variability in quantifying the severity of regional dysfunction.

Data Interpretation, Statistical↗
PubMed1996

Transesophageal echocardiography in myocardial revascularization: II. Influence on intraoperative decision making.

This study was conducted to determine how transesophageal echocardiography (TEE) guides intraoperative decision making during myocardial revascularization. Although its usefulness in influencing clinical decision making during cardiac valvular surgery is well documented, the clinical utility of TEE in patients undergoing myocardial revascularization is less clear. We studied the performance of five community-based, full-time cardiac anesthesiologists during 75 surgical procedures. All patients were monitored with radial artery and pulmonary artery catheters as well as biplane TEE. Immediately after each clinical intervention, the anesthesiologist was asked to determine how real-time TEE influenced the therapy, which single monitor was most influential, and why each therapy was initiated. Of the 584 interventions, TEE was the single most important guiding factor in 98 instances (17%). Interventions involving fluid administration contributed to 277 of 584 (47%) of the total clinical decisions. TEE was the most important monitor influencing fluid administration in 82 of 277 instances (30%), versus the pulmonary artery catheter in 20 of 277 instances (7%). TEE was the single most important monitor in guiding other therapies as follows: antiischemic therapy, 8 of 38 = 21%; vasopressor or inotrope administration, 4 of 115 = 3%; vasodilator therapy, 1 of 38 = 3%; antiarrhythmic medications, 0 of 16 = 0%; and depth of anesthesia, 1 of 72 = 1%. In 2 of 75 patients (3%), critical surgical interventions were made solely on the basis of TEE. Also, TEE was found to act in concert with other monitors in 254 of 584 interventions (43%). TEE is often influential in guiding decision making in myocardial revascularization when incorporated as a routine monitor in the intraoperative setting. Information from TEE has been most commonly used to guide the management of fluid administration and institution of antiischemic therapy. In a small subset of patients, TEE appears to be useful in guiding critical surgical interventions.

Adult↗
PubMed1994

Left ventricular end-systolic cavity obliteration as an estimate of intraoperative hypovolemia.

BACKGROUND: Transesophageal echocardiography is increasingly used intraoperatively as a monitor of ventricular function and volume. Although obliteration of the left ventricular (LV) cavity at end-systole is interpreted as indicative of intraoperative hypovolemia, this relation has not been demonstrated directly. METHODS: We continuously monitored the LV short axis by using transesophageal echocardiography and determined the relation between acute changes in LV area and hemodynamic variables in 139 patients undergoing elective coronary artery bypass graft surgery. The end-diastolic areas (EDA) and end-systolic areas were calculated during the control state (after anesthetic induction) and during LV end-systolic cavity obliteration. RESULTS: Thirty-nine of 139 patients had episodes of LV cavity obliteration. Mean LV end-systolic area decreased significantly from the control to obliterated state (7.29 +/- 2.56 to 4.00 +/- 1.46 cm2, P = 0.0001). The corresponding mean LV EDA also significantly decreased from the control to obliterated state (18.18 +/- 4.36 to 12.92 +/- 3.74 cm2, P = 0.0001). Mean ejection fraction area increased from 0.609 +/- 0.095 (control) to 0.692 +/- 0.083 (obliteration) (P < 0.0001). Of these 39 episodes, 31 (80%) were associated with a greater than 10% decrease in EDA relative to the initial value after induction of anesthesia and tracheal intubation; 4 (10%) with increases in ejection fraction area only; and an additional 4 (10%) with no substantial change in either the EDA or ejection fraction area. Overall, LV cavity obliteration was not associated with hemodynamic changes. CONCLUSIONS: Our study demonstrates that LV cavity obliteration is rarely preceded by any acute alteration in hemodynamic parameters. Although end-systolic cavity obliteration detected by intraoperative transesophageal echocardiography is frequently associated with decreases in EDA, not every instance of end-systolic cavity obliteration is indicative of decreased left ventricular filling.

Coronary Artery Bypass↗
PubMed1994

An initial multicenter, randomized controlled trial on the safety and efficacy of acadesine in patients undergoing coronary artery bypass graft surgery. SPI Research Group.

Acadesine (5-amino-4-imidazole carboxamide riboside) is a purine nucleoside analog that has been shown in animals to reduce myocardial ischemic injury by selectively increasing the availability of adenosine in ischemic tissues. Because patients undergoing coronary artery bypass graft (CABG) surgery are especially vulnerable to developing myocardial ischemia, we investigated whether perioperative use of this adenosine-regulating drug with potential anti-ischemic properties could modify the incidence and severity of perioperative myocardial ischemia. The goals of this study were to evaluate safety and the effects of acadesine on myocardial ischemia, left ventricular function, and, secondarily, on adverse clinical outcomes (myocardial infarction, heart failure, life-threatening dysrhythmias, and death) in patients undergoing CABG surgery. One hundred sixteen patients were randomized to receive one of three continuous intravenous dosing regimens (placebo [control] or one of two doses of acadesine [high- and low-dose infusion]) in double-blind fashion intraoperatively and in the early postoperative period (total infusion time was 7 h). Multidose cold crystalloid cardioplegia (each containing either acadesine or placebo) was used for myocardial protection. All were monitored for potentially drug-related adverse events and the presence of myocardial ischemia was assessed by continuous Holter electrocardiography (ECG) and transesophageal echocardiography (TEE). All patients received standardized anesthetic, surgical, and hemodynamic management during the intraoperative period. All research data (ECG, TEE, outcome data) were evaluated at the coordinating center (San Francisco) in blinded fashion to ensure that uniform data analysis criteria were employed. The administration of acadesine was safe: mild increases in plasma uric acid (a metabolite of acadesine) occurred only in patients receiving high doses (mean increase 1.6 +/- 0.2 mg/dL) and were without clinical sequelae. Before drug administration in the preoperative period (baseline), the incidence and severity of ECG ischemia did not differ among the three groups (placebo = 18%; low-dose = 14%; high-dose = 14%). During prebypass, the incidence of ECG ischemia was similar in all three groups (0%, 3%, 3%, respectively). The incidence of TEE ischemia was numerically lower in the two acadesine groups (high-dose = 6%, low-dose = 15%) than in the control group (19%), but this was not statistically significant (P = 0.22). During postbypass, the incidence of ECG ischemia was 11% in the high-dose group, 22% in the low-dose group, and 18% in the control group (P = 0.42), and TEE ischemia was similar in incidence in all groups (placebo = 29%; low dose = 27%; high-dose = 24%) (P = 0.86).(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗