A pharmacodynamic study of clopidogrel in chronic hemodialysis patients.

Combination antiplatelet agents, particularly aspirin and ticlopidine, have found increased use in the prevention of arterial thrombosis. Clopidogrel, a thienopyridine derivative, like ticlopidine was recently approved by the U.S. Food and Drug Administration (FDA) for the reduction of ischemic events in patients with myocardial infarction, stroke, or peripheral arterial disease and appears to have much less hematologic toxicity than ticlopidine has. Thrombosis of hemodialysis access grafts is a major cause of morbidity in this patient population. Combination antiplatelet agents may be particularly useful in the prevention of hemodialysis access graft thrombosis. In preparation for such a study, we have performed a pharmacodynamic study of the platelet inhibitory effects of clopidogrel in patients on maintenance hemodialysis. Nine chronic hemodialysis patients were studied. Baseline platelet aggregation studies were performed, after which the subjects were begun on clopidogrel 75 mg daily. Platelet aggregation studies were repeated after 14 days of therapy. Drug was stopped and a final set of platelet aggregation studies were performed 7 days later. Because clopidogrel acts by inhibiting adenosine diphosphate (ADP)-induced platelet aggregation, we used ADP as the agonist in the platelet aggregation studies. We also measured the time required to achieve hemostasis after removing the dialysis needles at the termination of a dialysis session. Patients were carefully monitored for any adverse reaction to clopidogrel. Fourteen days' treatment with clopidogrel inhibited ADP-induced platelet aggregation from 48 to 23% with ADP 2 microM (P=0.0113), from 59 to 38% with ADP 5 microM (P=0. 0166), and from 66 to 44% with ADP 10 microM (P=0. 0172). This inhibition of platelet aggregation was reversed 7 days after stopping clopidogrel. Clopidogrel administration did not affect the time required to achieve hemostasis after removal of the dialysis needles. No adverse reactions were noted. No patient had evidence of bleeding, rash or gastro-intestinal (GI) upset. Clopidogrel inhibits ADP-induced platelet aggregation in subjects receiving chronic maintenance hemodialysis. The magnitude of inhibition is similar to that reported in nonuremic subjects with atherosclerosis. This inhibition is reversible within 7 days of discontinuing the drug. No adverse reactions to the drug were noted in this short-term (14-day) trial.

Decreased digital flow persists after the abatement of cocaine-induced hemodynamic stimulation.

This study determined whether the development of delayed ischemic sequelae due to cocaine use--after the return of arterial blood pressure (BP) and heart rate to near-baseline values--may be attributable to regional vasoconstriction which persists beyond the acute systemic hemodynamic response. Five cocaine-using volunteers received intravenous infusions of saline placebo and cocaine 0.50 mg/kg several days apart in a double-blinded cross-over design. The intensity and duration of the cocaine-induced decrease in peripheral blood flow (as documented by laser Doppler flowmetry of the finger) were compared to the increases in BP (obtained with a Dinamap) and heart rate using paired t-test and repeated-measures analysis of variance. A significant increase in BP and a significant decrease in finger flow were noted by the first time point (5 min). Within 15 min, cocaine induced a 36% +/- 5% increase in BP and a 73% +/- 18% decline in finger flow (P < 0.05 for difference between percent change in BP and percent change in flow). Dinamap(systolic) and Dinamap(diastolic) returned to within 15% of baseline within 30 min, while finger flow remained more than 50% below baseline for the remainder of the 60-min study period (P < 0.05). Changes in heart rate paralleled those in BP. Except for isolated cases of documented coronary vasoconstriction in patients presenting with complications after cocaine use, this study is the first to document the persistence of cocaine-induced vasoconstriction of a sensitive vascular bed beyond the hypertensive response. It thus helps to explain the development of ischemic injury after cocaine use despite a stable rate-pressure product.

Preoperative anxiety in children. Predictors and outcomes.

OBJECTIVE: To determine predictors and behavioral outcomes of preoperative anxiety in children undergoing surgery. DESIGN: A prospective, longitudinal study. SETTING: A university children's hospital. PARTICIPANTS: One hundred sixty-three children, 2 to 10 years of age (and their parents), who underwent general anesthesia and elective surgery. MAIN OUTCOME MEASURES: In the preoperative holding area, anxiety level of the child and parents was determined using self-reported and independent observational measures. At separation to the operating room, the anxiety level of the child and parents was rated again. Postoperative behavioral responses were evaluated 3 times (at 2 weeks, 6 months, and 1 year). RESULTS: A multiple regression model (R2 = 0.58, F = 6.4, P = .007) revealed that older children and children of anxious parents, who received low Emotionality, Activity, Sociability, and Impulsivity (EASI) ratings for activity, and with a history of poor-quality medical encounters demonstrated higher levels of anxiety in the preoperative holding area. A similar model (R2 = 0.42, F = 8.6, P = .001) revealed that children who received low EASI ratings for activity, with a previous hospitalization, who were not enrolled in day care, and who did not undergo premedication were more anxious at separation to the operating room. Overall, 54% of children exhibited some negative behavioral responses at the 2-week follow-up. Twenty percent of the children continued to demonstrate negative behavior changes at 6-month follow-up, and, in 7.3% of the children, these behaviors persisted at 1-year follow-up. Nightmares, separation anxiety, eating problems, and increased fear of physicians were the most common problems at 2-week follow-up. Multivariate analysis demonstrated that child's age, number of siblings, and immediate preoperative anxiety of the child and mother predicted later behavioral problems. CONCLUSIONS: Variables such as situational anxiety of the mother, temperament of the child, age of the child, and quality of previous medical encounters predict a child's preoperative anxiety. Although immediate negative behavioral responses develop in a relatively large number of young children following surgery, the magnitude of these changes is limited, and long-term maladaptive behavioral responses develop in only a small minority.

Correlates and consequences of diffuse atherosclerosis in men with coronary heart disease. Veterans Affairs High-Density Lipoprotein Intervention Trial Study Group.

BACKGROUND: Peripheral atherosclerosis is a strong and independent predictor of mortality even in patients with known coronary heart disease. However, the prevalence, correlates, and potential adverse effects on quality of life associated with combined coronary heart disease and clinically evident cerebrovascular or lower-extremity atherosclerosis are not known. Identification of patients with "diffuse atherosclerosis" may enhance treatment of modifiable risk factors and alter therapeutic strategies. METHODS: We conducted a cross-sectional analysis of 2531 men younger than 73 years with coronary heart disease, low-density lipoprotein cholesterol levels of 3.62 mmol/L (140 mg/dL) or less, and high-density lipoprotein cholesterol level of 1.03 mmol/L (40 mg/dL) or less who were participating in Department of Veterans Affairs Cooperative Study 363 (the Veterans Affairs High-Density Lipo-protein Intervention Trial. Baseline demographic, medication, comorbidity, and atherosclerotic risk factor data were assessed by means of a standardized questionnaire. All plasma lipid levels were determined after a 12-hour fast by a central standardized lipid laboratory. Health status was determined by baseline reported symptoms, medical comorbidities, and the Psychological General Well-being Index. Clinically evident diffuse atherosclerosis was defined as a documented history of lower-extremity atherosclerosis or cerebrovascular disease. RESULTS: The mean age of all participants was 63.5 years. The mean plasma lipid values were as follows: total cholesterol, 4,52 mmol/L (174.6 mg/dL); high-density lipo-protein cholesterol, 0.81 mmol/L (31.5 mg/dL); low-density lipoprotein cholesterol, 2.88 mmol/L (111.2 mg/dL); and triglycerides, 1.81 mmol/L (160.6 mg/dL). Diffuse atherosclerosis was present in 525 (21%). Lower-extremity atherosclerosis was reported in 10%, while cerebrovascular disease was present in 13%. After controlling for other variables, the following factors were associated with the presence of diffuse atherosclerosis: increased age, being unmarried, being retired, having less than a high school education, increased alcohol use, hypertension, cigarette smoking, and diabetes. There was no association between lipid levels and the presence of diffuse atherosclerosis. After adjustment for age, race, and comorbidities, men with diffuse disease still had a reduced quality of life compared with men without diffuse atherosclerosis, as defined by having a greater number of clinical symptoms, lower psychological well-being scores, and more advanced or complicated coronary heart disease. CONCLUSIONS: Clinically evident diffuse atherosclerosis is common in men with coronary heart disease and low levels of high-density lipoprotein cholesterol. Because diffuse atherosclerosis is associated with a reduced quality of life and several modifiable risk factors, early detection and aggressive risk factor intervention appear justified.

Reduction of postburn hyperalgesia after local injection of ketorolac in healthy volunteers.

BACKGROUND: Nonsteroidal antiinflammatory drugs may be particularly effective against prostaglandin-mediated, post-injury hyperalgesia and related inflammatory pain. However, their usefulness may be limited by their systemic side effects. The current study determined if local effectiveness can be achieved by low-dose intradermal nonsteroidal antiinflamatory drug administration. METHODS: Ten healthy volunteers were asked to make magnitude estimations of the pain induced by a contact thermal stimulator at 1 degree C increments between 43 and 51 degrees C at three 1 x 1 cm study sites on each forearm during three study phases:(1) baseline; (2) after pretreatment with 10 microl 0.9% saline (n=1 site on each forearm), 0.3 mg ketorolac (n=1 on each forearm), or nothing (n=1 on each forearm); and (3) after "injury" by a mild burn at the ketorolac- and saline-treated sites on one arm or by injection of 10 nmol bradykinin at all three sites on the other arm. The effects of pretreatment on the pain induced by thermal testing were assessed using repeated-measures analysis of variance. RESULTS: Pretreatment with ketorolac had a selective effect on the postburn injury hyperalgesia, reducing the increase in pain intensity (P<0.05) but not the decline in pain threshold. It had no effect on the responses to thermal stimuli before injury or on the pain of burning, which were similar at ketorolac- and saline-treated sites. The effect of pretreatment with ketorolac on bradykinin-induced hyperalgesia was not achieved after bradykinin injection at sites pretreated with saline as well as ketorolac.

Measurement of exposure to environmental tobacco smoke in pregnant women.

The authors compared three methods used to measure exposure to environmental tobacco smoke in pregnant women: personal air monitor, urine cotinine, and questionnaire. Environmental tobacco smoke exposure assessment methods were compared for agreement using Cohen's Kappa and the Spearman rank order correlation coefficient. Women who reported exposure had significantly higher levels of air nicotine concentration compared with women who reported no exposure, but urine cotinine did not differ. Air nicotine was more highly correlated with home exposure (r = 0.34) than work exposure (r = 0.18). Urine cotinine correlated with work exposure (r = 0.14) but neither home nor social exposure. Agreement was "fair" (Kappa = 0.29) when self-reported exposure was compared with air monitor, but agreement was "poor" when urine cotinine was compared with self-report (Kappa = 0.08) and air monitor (Kappa = 0.10). In low environmental tobacco smoke exposure environments, all three methods for measuring exposure may have a role, although modification to monitoring protocols will be needed to improve monitoring sensitivity and exposure classification.

Automated echocardiographic analysis. Examination of serial intraoperative measurements.

BACKGROUND: Although transesophageal echocardiography allows continuous intraoperative cardiac monitoring, the technique has been limited by the lack of a method for realtime, quantitative assessment of cardiac chamber size and systolic function. Automated border detection (ABD), based on an analysis of integrated backscatter, is a new technique that is purported to provide real-time, quantitative assessment of left ventricular (LV) areas and fractional area change (FAC). A prospective investigation was designed to assess the accuracy and trending capability of ABD during continuous intraoperative monitoring. METHODS: In 16 patients monitored throughout noncardiac surgical procedures, serial real-time estimates of LV end-diastolic area (EDA), end-systolic area (ESA), and FAC by ABD were compared with paired off-line manual measurements made by two experiences echocardiographers. RESULTS: There was a high correlation between real-time ABD estimates of LV ESA (r = 0.93), EDA (r = 0.89), and FAC (r = 0.90) to those of the off-line technique. The automated technique systematically underestimated both EDA and ESA, resulting in a small underestimation of FAC. The automated technique demonstrated an accuracy rate of 96% in tracking serial changes in LV area. The technique performed with an 83% sensitivity and 85% specificity for detecting acute changes in LV area. CONCLUSIONS: This analysis of serial intraoperative echocardiograms demonstrates the accuracy of ABD to estimate LV area in real time and to track serial changes in cardiac area during surgery. Although ABD is an automated technique, application by personnel experienced in its operation and an echocardiographic system that includes lateral-gain adjustment controls are recommended for its optimal performance.

Infant apnea detection after herniorrhaphy.

STUDY OBJECTIVE: To elucidate risk factors for apnea in preterm infants discharged from the hospital and in full-term healthy infants. To determine the efficacy of real-time cardiopulmonary monitoring versus computerized storage and retrieval for infants at risk. STUDY DESIGN: Prospective study. SETTING: Operating rooms and pediatric patient care units of university medical center. PATIENTS: 27 preterm infants and 20 full-term infants no more than 60 weeks' post-conceptional age, who were admitted for elective herniorrhaphy. INTERVENTIONS: Infants were monitored before and after herniorrhaphy with general anesthesia using an infant apnea impedance monitor, pulse oximetry, and nursing observation. MEASUREMENTS AND MAIN RESULTS: Demographic information and medical history were correlated with postoperative apnea. The sensitivity and specificity of nursing observation and oximetry were compared with computerized apnea monitors. Five patients (11%, four preterm, one full-term) were apneic postoperatively as recorded by computerized pneumocardiography. Previous apnea history, gestational age at birth, and postconceptional age at operation positively correlated with postoperative apnea. Nursing observation failed to detect 4 of 5 patients with documented apnea (sensitivity 20%, positive predictive value 50%). Pulse oximetry failed to detect 3 of 5 patients with apnea (sensitivity 40%, positive predictive value 66%). CONCLUSIONS: Although it is easier to predict postoperative respiratory dysfunction in previously sick or very young infants, absolute predictability for all neonates remains elusive. Clinical monitors with both storage and retrieval capabilities and real-time monitoring increase our ability to detect significant events in children at risk for apnea after herniorrhaphy.

Peripheral assessment of phenylephrine-induced vasoconstriction by laser Doppler flowmetry and its potential relevance to homeostatic mechanisms.

BACKGROUND: Cutaneous laser Doppler flowmetry enables monitoring of changes in skin perfusion by quantifying the phase shift of laser light induced by moving red blood cells under a fiberoptic probe. It thus can identify the presence of and response to a vasoconstrictive stimulus. However, aspects of the technique must be defined before it can be used with maximum effectiveness. We evaluated the responses of two different laser Doppler outputs, the concentration of moving blood cells (CMBC) and red cell flux (CMBC times cell velocity), and the responses at two sites of probe application, the finger and forearm, during systemic infusions of phenylephrine. METHODS AND RESULTS: Eight healthy volunteers were monitored with a brachial blood pressure cuff, ECG, and laser Doppler flowmeter probes applied to the palmar surface of the fourth finger and volar forearm of the arm opposite the pressure cuff. After baseline readings were obtained, the subjects received three 10-minute intravenous infusions of phenylephrine at rates of 0.4, 0.8, and 1.6 micrograms.kg-1.min-1. The two parameters, flux and CMBC, trended similarly. Flux and CMBC at the finger declined significantly in response to each infusion (P < .05 using repeated-measures ANOVA with Duncan's multiple range test). In contrast, flux and CMBC of the forearm had highly variable responses, with an overall increase during each infusion (P < .05 for % delta of forearm versus % delta of finger readings during the 0.4 microgram.kg-1.min-1 infusion). Heart rate declined significantly during each infusion, consistent with a baroreceptor-mediated response, even though systolic and diastolic blood pressures each increased by less than 2 mm Hg during the 0.4 microgram.kg-1.min-1 infusion. CONCLUSIONS: As expected, laser Doppler readings at the finger decreased during infusion of an alpha 1-agonist. Although, like the digital vessels, forearm vessels have the potential to constrict, the increases in forearm readings suggest that these vessels are highly susceptible to homeostatic responses. The increase in CMBC (a parameter that is sensitive primarily to local changes in vascular caliber) suggested vasodilation of the underlying vessels. The forearm vasodilation and the concomitant decline in heart rate most likely represented vagally mediated baroreceptor activity, which was altered even though blood pressure changed minimally during the 0.4 microgram.kg-1.min-1 infusion. Thus, integrated assessment of skin perfusion at the finger and forearm may provide valuable information about the direct and indirect effects of a vasoactive stimulus. The present application of laser Doppler flowmetry suggests activation of vasodilatory reflexes despite minimal changes in blood pressure.

Intraoperative cardiac output monitoring: comparison of impedance cardiography and thermodilution.

Impedance cardiography (IC) is a noninvasive, simple to use method of cardiac output (CO) determination. A prospective evaluation of IC monitoring was performed in 50 patients undergoing noncardiac surgery. IC CO measurements (NC-COM3-Revision 7, BoMed Manufacturing) were compared to simultaneous measurements of thermodilution (TD) CO to assess the validity of this technique for intraoperative cardiac monitoring. Adequate impedance signals could not be obtained in 7 of the 50 patients. IC CO measurements were highly correlated to TD CO (P < .005), with a correlation coefficient r = 0.84. Bias analysis, however, indicated clinically significant disagreement between the two techniques. IC CO tended to underestimate TD CO (mean bias = -0.41 L/min) and the SD of the bias was 1.0 L/min (95% level of agreement 1.6 to -2.4 L/min). Trending data showed IC to accurately track the direction of TD CO changes but to underestimate their magnitude (r = 0.60, intercept -0.7 L/min, slope 0.47). Factors that may have impaired the performance of IC in this study include the high prevalence of cardiac disease in the study population and electrical noise in the operative setting. Further development of IC appears warranted if it is to prove useful as an intraoperative cardiac monitor.

Management of tracheobronchial and esophageal foreign bodies in children: a survey study.

STUDY OBJECTIVE: To assess the current anesthetic management for aspiration of a foreign body into the airway and esophagus of a young child. DESIGN: Questionnaire study. MEASUREMENTS AND MAIN RESULTS: A questionnaire regarding choice of induction technique in a variety of foreign body clinical scenarios was sent to 1,342 anesthesiologists, all members of the Society for Pediatric Anesthesia. The foreign body, either a coin (penny) or a safety pin (open), was positioned on radiography in a variety of anatomic locations. Depending on the foreign body location, the patient was either asymptomatic or exhibited symptoms. Participants indicated their choice of induction for each situation. Of the 1,342 questionnaires mailed, there were 838 respondents (62.4%). Coins and pins in the gastroesophageal tract were managed mostly by a rapid-sequence induction (p < 0.001). Coins and pins at all levels in the tracheobronchial tree were managed most often by a mask induction with no cricoid pressure (p < 0.001). Although 14.5% of respondents chose awake and sedated technique for a foreign body in the supraglottic area, few chose this technique for a foreign body in other locations. The type of object did not affect the choice of drugs for induction of anesthesia in most anatomic locations. Respondents with limited pediatric anesthesia experience used inhalation induction much less often than did those with more experience. Multiple-logistic regression analysis showed that both number of years in practice and type of practice (university, private, hybrid) were predictors for the induction. CONCLUSIONS: These data indicate that inhalation induction is favored most often for removal of foreign bodies in the airway, while intravenous induction is preferred for removal of foreign bodies in the gastroesophageal tract. In addition, practice type, greater percentage of time spent in pediatric anesthesia, and greater experience are related to a higher likelihood of inhalation induction.

Lack of effect of sphenopalatine ganglion block with intranasal lidocaine on submaximal effort tourniquet test pain.

BACKGROUND AND OBJECTIVES: The present study examined whether sphenopalatine ganglion block (SPGB) causes a reduction in the response to acute nociceptive input that may account for the SPGB-induced relief reported by many patients with chronic pain. METHODS: In a double-blind, crossover design, 16 healthy volunteers underwent separate 15-minute submaximal effort tourniquet tests before and after SPGB with 20% lidocaine plus 1:100,000 epinephrine (SPGBlidocaine) or placebo (SPGBsaline). Responses during each minute of tourniquet inflation were converted to a 1 to 16 scale and classified as nothing (1), mild sensation (2-4), strong sensation (5-7), slightly painful (8-10), definitely painful (11-13), and severely painful (14-16). RESULTS: Maximum pain scores reached 12.6 +/- 2.5 (mean +/- SD) pre-SPGB, 10.9 +/- 3.5 after SPGBsaline, and 11.1 +/- 2.5 after SPGBlidocaine. No significant differences were noted between SPGBlidocaine and SPGBsaline at any of the 15 time points (p = NS by repeated measures ANOVA and paired t-test). However, retrospective grouping of time points noted that scores after SPGBlidocaine were lower in the "strong sensation" range. CONCLUSION: SPGB does not lessen acute extremity pain to a significant degree and is not in and of itself an effective means of analgesia for acute pain. Its potential impact on nociceptive stimuli that elicit a "strong sensation" (i.e., a score of 5-7 in the present study) should be evaluated in hyperpathic pain states and in states with exaggerated aversive responses.

The patient care evaluation system: patients' perception of anesthetic care.

Our department's Patient Care Evaluation Survey was developed to measure the patients' perception of the care they received by our anesthesia caregivers (attending physicians, residents, and certified registered nurse anesthetists [CRNAs]), and identify those areas of patient contact which might require improvement in the delivery of anesthesia. The survey instrument (a personal letter sent by the chairman), is mailed to randomly selected patients two weeks following discharge from the hospital or ambulatory surgery center. Patients rated the anesthesia care they received from one (poor) to 10 (excellent) in three areas: the preoperative visit, the postoperative visit, and overall satisfaction. From October 1986 to October 1991, a total of 2,374 (n = 2,374) questionnaires representing a random sample of 99,964 anesthetics, were sent to patients. Fifty-four percent or 1,291/2,374 patients returned the survey. A high degree of patient satisfaction is seen for all categories: the preoperative visit, (mean score of 9.17 +/- 1.6); the postoperative visit (8.33 +/- 2.7); and overall satisfaction (9.15 +/- 1.7). Of the responses returned, 0.9% of the patients surveyed rated their interaction with the department as unsatisfactory in all three areas; 2.6% in two areas; 10.8% in at least one area. The Patient Care Evaluation system has served as an important means of feedback for medical, educational, and administrative goals of the department.

Liquid crystal skin thermometry: an accurate reflection of core temperature?

Oesophageal, rectal, bladder, tympanic and pulmonary artery sites are used intraoperatively to measure body temperature. However, the temperatures measured at each site have different physiological and practical importance. The present two-part study sought to compare liquid crystal (CR) skin temperature with other temperature monitors which are used routinely during surgery. The first part compared CR with oesophageal (OS) temperature during general inhalational anaesthesia. The second part compared CR with OS, pulmonary artery (PA), and bladder (BL) temperatures during the periods of rapid temperature change associated with cardiopulmonary bypass (CPB). During the first part, the mean difference between OS and CR was -0.14 +/- 0.85 degrees C; this difference remained consistent over time (P < 0.05 by repeated measures analysis of variance). During the second part, the difference in temperature readings between CR and each of the other monitors remained consistent except for CR vs PA and CR vs OS during the cooling period of CPB, when the iced cardioplegia slush directly affected the PA and OS temperatures. This study suggests that CR, an inexpensive and noninvasive means of temperature monitoring, reflects trends in temperature changes in the clinical setting.

The relationship between "normal" transesophageal color-flow Doppler-defined tricuspid regurgitation and thermodilution right ventricular ejection fraction measurements.

Twenty coronary artery revascularization patients, aged 58 +/- 15 years, were studied intraoperatively to define the impact of Doppler-defined tricuspid regurgitation on measurement of thermodilution right ventricular ejection fraction (50 msec response pulmonary artery catheter). Right ventricular function was also estimated using a measurement technique independent of flow patterns across the tricuspid valve (transesophageal two-dimensional echocardiographic 5.0 MHz phased-array transducer). Measurements included transverse plane long- and short-axis planimetered area ratio, respectively, and tricuspid annular plane systolic excursion ratio (ratio = end-diastolic minus end-systolic value divided by end-diastolic value). Data were expressed as thermodilution-echocardiographic gradients, ie, thermodilution ejection fraction minus long-axis planimetered area ratio, short-axis planimetered area ratio, and tricuspid annular plane systolic excursion ratio, respectively. Tricuspid regurgitation was quantified by color-flow Doppler perimetry of maximal regurgitation jet area and analysis of transduced right atrial pressure waveform. Doppler estimates were expressed as absolute values and as a function of corresponding atrial area (tricuspid regurgitation index = planimetered jet area divided by right atrial area). Data were obtained following endotracheal intubation, sternotomy, pericardiotomy, cardiopulmonary bypass, and chest closure. Data were evaluated by regression analysis, with separate analyses performed for each time period. Profiles were unassociated with right atrial pressure waveform abnormalities. There was no significant relationship between thermodilution ejection fraction variance values and tricuspid regurgitation jet area or regurgitation index, respectively. In each measurement period, thermodilution-echocardiographic gradients were also unrelated to the tricuspid regurgitation estimates.(ABSTRACT TRUNCATED AT 250 WORDS)

The pressure rate quotient is not an indicator of myocardial ischemia in humans. An echocardiographic evaluation.

BACKGROUND: The pressure rate quotient (PRQ; mean arterial pressure/heart rate [MAP/HR]) less than one (PRQ < 1) has been proposed as a simple, clinically available hemodynamic index of myocardial ischemia. Recent investigations using electrocardiography (ECG) detection of myocardial ischemia have not found this index reliable. We prospectively compared PRQ < 1 to detection of myocardial ischemia via transesophageal echocardiography (TEE) and ECG in patients undergoing elective coronary artery bypass graft. METHODS: Forty-six of 50 patients admitted into the study had acceptable data acquisition. Calibrated ECG leads II and V5 were recorded with a computerized ST-segment analyzer. Hemodynamic data were stored at 2-min intervals. After tracheal intubation, a 5.0-MHz TEE probe was inserted. Electrocardiography-detected ischemia was defined as new onset ST-segment deviation (> or = 1 mm) lasting for > 1 min. Transesophageal echocardiography determination of ischemia was worsening of wall motion > or = 1 grade and lasting > 1 min. PRQ < 1 was compared to ECG and/or TEE as a predictor or indicator of myocardial ischemia. RESULTS: Electrocardiography ischemia occurred during 230 intervals in 10 patients, and in only 41 of 230 (18%) was PRQ < 1. Transesophageal echocardiography-defined ischemia occurred during 592 intervals in 9 patients, and in 119 of 592 (20%) PRQ < 1. Compared to ECG and TEE, PRQ < 1 had a low sensitivity (21%) and poor positive predictive value (25%). CONCLUSIONS: Pressure rate quotient < 1 is an unreliable indicator and predictor of myocardial ischemia when evaluated by ECG, TEE, and the combination of these modalities in patients undergoing coronary artery bypass graft surgery.

Thermodilution right ventricular ejection fraction measurement reproducibility--a study in patients undergoing coronary artery bypass graft surgery.

OBJECTIVE: To assess the effects of heart rate, right ventricular systolic performance (ejection fraction), chamber dimensions, and flow rate (cardiac index) on the reproducibility of algorithm-derived triplicate thermodilution right ventricular ejection fraction measurements. DESIGN: Prospective study; combined hemodynamic and echocardiographic clinical evaluation. SETTING: Operating room in a university hospital. PATIENTS: Twenty-one coronary artery bypass graft patients. MEASUREMENTS AND MAIN RESULTS: The right atrial delivery site was positioned by analysis of transduced pressure waveform and echocardiographic imaging of tracer agitated saline cavitations. Measurement reproducibility was quantified by determining the variation (standard deviation) within 101 triplicate thermodilution measurement sets. There was no significant relationship between measurement reproducibility and estimates of right atrial area (21.6 +/- 6.9 cm2), diameter (5.1 +/- 0.8 cm) and supero-inferior length (5.1 +/- 0.9 cm) and right ventricular maximal minor axis diastolic diameter (4.21 +/- 1.05 cm). Reproducibility was also unrelated to right ventricular end-diastolic volume index (97.9 +/- 32.7 mL/m2) and cardiac index (2.9 +/- 0.9 L/min/m2). Measurement reproducibility was directly related to mean right ventricular ejection fraction (0.39 +/- 0.14) and inversely related to heart rate (80.8 +/- 18.6 beats/min) (p < .01 and < .001, respectively). CONCLUSIONS: Thermodilution-derived right ventricular ejection fraction measurement reproducibility was unrelated to estimates of right atrial and ventricular dimensions and cardiac index. Measurement reproducibility was a direct function of right ventricular systolic performance and an indirect function of heart rate. Measurement should be interpreted with these constraints in mind.

Transesophageal echocardiographic evaluation of aortic valve integrity with antegrade crystalloid cardioplegic solution used as an imaging agent.

Forceful intravascular injection of crystalloid causes microbubble (cavitation) formation. The resulting ultrasound-opaque medium is widely used in echocardiography as a source of contrast. The following study was performed to determine the feasibility of using antegrade crystalloid cardioplegic solution as a transesophageal two-dimensional echocardiographic imaging agent to evaluate aortic valve integrity. In patients with preexisting aortic regurgitation (n = 12), cardioplegic solution administration (driving pressure 150 to 200 mm Hg) was associated with the appearance of intracardiac cavitations in 12 of 12 patients. Among patients without preexisting valve dysfunction (n = 22), intracardiac cavitations were manifested in 20 of 22, with extension of the cavitations to the left atrium in 17. Associated cardiac dimensions (left ventricular outflow tract area and left ventricular diameter) did not exceed preceding cardiopulmonary bypass values in these patients (2.0 +/- 1.6 cm2 versus 2.6 +/- 1.2 cm2 and 1.4 +/- 0.7 cm versus 1.5 +/- 0.8 cm, respectively). It was concluded that antegrade crystalloid cardioplegic solution can be used as an echocardiographic contrast agent in this context. The inability to establish a relationship between the extent of cardioplegic intracardiac penetration and left ventricular dimensional changes limits the technique, as presently employed, to qualitative analysis of valve dysfunction.