Significant Differences In Hemodynamic Responses Research Articles

Timing of vasopressin initiation and mortality in patients with septic shock: analysis of the MIMIC-III and MIMIC-IV databases

Backgroundvasopressin is commonly used as a second-line vasopressor for patients with septic shock, but the optimal timing of initiation is uncertain. This study was designed to investigate when vasopressin initiation may be beneficial for 28-day mortality in septic shock patients.MethodsThis was a retrospective observational cohort study from the MIMIC-III v1.4 and MIMIC-IV v2.0 databases. All adults diagnosed with septic shock according to Sepsis-3 criteria were included. Patients were stratified into two groups based on norepinephrine (NE) dose at the time of vasopressin initiation, defined as the low doses of NE group (NE<0.25 µg/kg/min) and the high doses of NE group (NE ≥ 0.25 µg/kg/min). The primary end‐point was 28‐day mortality after diagnosis of septic shock. The analysis involved propensity score matching (PSM), multivariable logistic regression, doubly robust estimation, the gradient boosted model, and an inverse probability‐weighting model.ResultsA total of 1817 eligible patients were included in our original cohort (613 in the low doses of NE group and 1204 in the high doses of NE group). After 1:1 PSM, 535 patients from each group with no difference in disease severity were included in the analysis. The results showed that vasopressin initiation at low doses of NE was associated with reduced 28-day mortality (odds ratio [OR] 0.660, 95% confidence interval [CI] 0.518–0.840, p < 0.001). Compared with patients in the high doses of NE group, patients in the low doses of NE group received significantly shorter duration of NE, with less intravenous fluid volume on the first day after initiation of vasopressin, more urine on the second day, and longer mechanical ventilation-free days and CRRT-free days. Nevertheless, there were no significant differences in hemodynamic response to vasopressin, duration of vasopressin, and ICU or hospital length of stay.ConclusionsAmong adults with septic shock, vasopressin initiation when low-dose NE was used was associated with an improvement in 28-day mortality.

Light Up the Brain: An Exploratory Study of Applying Functional Near‐Infrared Spectroscopy in an Authentic Video Task

ABSTRACTDigital video (DV) is widely used in education settings; however, few researchers have explored the neurocognitive underpinnings of DV tasks. Functional near‐infrared spectroscopy (fNIRS) records neurological activity in real time, is robust to movement, and provides information about cognitive load and engagement levels during authentic learning tasks. This study used fNIRS to measure hemodynamic responses while eight participants completed a DV task. Statistically significant differences in hemodynamic responses during the editing and evaluation stages of the DV task were found. fNIRS can help researchers understand cognitive load and engagement levels during DV tasks, which can help inform learning and instruction.

Effect of Resistance Exercise with Blood Flow Restriction on Peripheral Oxygen Saturation and Cardiovascular Stress in Untrained Diabetic Women: A Cross and Randomized Study

This study aimed to analyze the effects of high-load (HL) resistance exercise (RE), low-load (LL) RE, and LL RE with blood flow restriction (LL + BFR) in peripheral oxygen saturation level (SpO2), heart rate (HR), and double product (DP: HR × systolic blood pressure [SBP]) in untrained women with type 2 diabetes (T2DM). Ten untrained women with T2DM (Age = 56.9 ± 7.4 years; BMI = 27.2 ± 4.2 kg/m2; and Diagnostic time = 10.6 ± 4.1 years) participated in this study. Participants attended a local gym for four non-consecutive days. During the first visit, arterial occlusion pressure (AOP) and predictive values of one maximum repetition (1RM) for knee extension exercise (KE) were assessed. The second, third, and fourth visits were randomly assigned to the following: HL RE (~65% of predicted 1RM in 3 sets of 10 repetitions), LL RE (~20% of predicted 1RM in 3 sets of 15 repetitions), and LL + BFR RE (~20% of predicted 1RM in 3 sets of 15 repetitions; 50% of AOP). HR, SBP e SpO2 were assessed before and immediately after each protocol. All protocols significantly increased the analyzed variables (p ≤ 0.05). There were no significant differences in hemodynamic responses between the protocols (p > 0.05). Therefore, resistance exercise with BFR seems to promote cardiovascular responses similar to traditional low and high load resistance exercise protocols in untrained diabetic women. Keywords: Double Product, Heart Rate, Ischemia, Hemodynamics, Kaatsu training, Resistance Training, Therapeutic Occlusion. Read more →

Effect of nutritive and non-nutritive sweeteners on hemodynamic responses to acute stress: a randomized crossover trial in healthy women

BackgroundThe mechanisms by which chronic stress increases the risk of non-communicable diseases remain poorly understood. On one hand, chronic stress may increase systemic vascular resistance (SVR) and blood pressure, which may lead to blood vessels injury and altered myocardial perfusion. On the other hand, chronic stress may promote the overconsumption of sugar-containing foods and favor obesity. There is indeed evidence that sweet foods are preferentially consumed to alleviate stress responses. The effects of nutritive and non-nutritive sweeteners (NNS) on hemodynamic stress responses remain however largely unknown.Objective/designThis study aimed at comparing the effects of sucrose-containing and NNS-containing drinks, as compared to unsweetened water, on hemodynamic responses to acute stress in twelve healthy female subjects. Acute stress responses were elicited by a 30-min mental stress (5-min Stroop’s test alternated with 5-min mental arithmetic) and a 3-min cold pressure test (CPT), each preceded by a resting baseline period. Hemodynamic stress responses were investigated by the repeated measurement of mean arterial pressure and the continuous monitoring of cardiac output by thoracic electrical bioimpedance measurement. SVR was selected as a primary outcome because it is a sensitive measure of hemodynamic responses to acute stress procedures.ResultsWith all three drinks, SVR were not changed with mental stress (P = 0.437), but were increased with CPT (P = 0.045). Both mental stress and CPT increased mean arterial pressure and heart rate (all P < 0.001). Cardiac output increased with mental stress (P < 0.001) and remained unchanged with CPT (P = 0.252). No significant differences in hemodynamic responses were observed between water, sucrose and NNS (stress × condition, all P > 0.05).ConclusionsThese results demonstrate that sucrose and NNS do not alter hemodynamic responses to two different standardized acute stress protocols.

Comparison of the effects of Truview PCD™ video laryngoscopy and Macintosh blade direct laryngoscopy in geriatric patients

Study ObjectiveTo compare the effects of Truview PCD™ video laryngoscopy (TVL) and Macintosh blade direct laryngoscopy (MDL) on hemodynamic responses observed during laryngoscopy and orotracheal intubation conditions in geriatric patients. DesignRandomized prospective study. SettingOperating room. PatientsOne hundred patients in the risk group American Society of Anesthesiologists I to III aged 65 years and older underwent elective surgery under general anesthesia. InterventionsThis prospective study was performed between January 2014 and February 2015 after institutional ethics committee approval. Patients were randomly allocated to 2 groups, namely, TVL and MDL. MeasurementsHemodynamic parameters, modified Cormack-Lehane grade, intubation period, and preoperative examination (age, sex, American Society of Anesthesiologists, modified Mallampati test score, and thyromental and sternomental distances) of patients were evaluated. Main ResultsThere were no statistically significant differences in hemodynamic responses (heart rates and mean arterial pressure) between the 2 groups (P>.05). The median intubation period in the TVL group was significantly higher than observed in the MDL group (t=4.594; P<.05). The laryngoscopy views in TVL group were better than the views in MDL group. The Cormack-Lehane grade in the TVL group was lower when compared to the MDL group. ConclusionThe TVL system does not provide significant hemodynamic response sparing or shorten orotracheal intubation times when compared to MDL in geriatric patients.

A Proof of Concept Study of Function-Based Statistical Analysis of fNIRS Data: Syntax Comprehension in Children with Specific Language Impairment Compared to Typically-Developing Controls.

Functional near infrared spectroscopy (fNIRS) is a neuroimaging technology that enables investigators to indirectly monitor brain activity in vivo through relative changes in the concentration of oxygenated and deoxygenated hemoglobin. One of the key features of fNIRS is its superior temporal resolution, with dense measurements over very short periods of time (100 ms increments). Unfortunately, most statistical analysis approaches in the existing literature have not fully utilized the high temporal resolution of fNIRS. For example, many analysis procedures are based on linearity assumptions that only extract partial information, thereby neglecting the overall dynamic trends in fNIRS trajectories. The main goal of this article is to assess the ability of a functional data analysis (FDA) approach for detecting significant differences in hemodynamic responses recorded by fNIRS. Children with and without SLI wore two, 3 × 5 fNIRS caps situated over the bilateral parasylvian areas as they completed a language comprehension task. FDA was used to decompose the high dimensional hemodynamic curves into the mean function and a few eigenfunctions to represent the overall trend and variation structures over time. Compared to the most popular GLM, we did not assume any parametric structure and let the data speak for itself. This analysis identified significant differences between the case and control groups in the oxygenated hemodynamic mean trends in the bilateral inferior frontal and left inferior posterior parietal brain regions. We also detected significant group differences in the deoxygenated hemodynamic mean trends in the right inferior posterior parietal cortex and left temporal parietal junction. These findings, using dramatically different approaches, experimental designs, data sets, and foci, were consistent with several other reports, confirming group differences in the importance of these two areas for syntax comprehension. The proposed FDA was consistent with the temporal characteristics of fNIRS, thus providing an alternative methodology for fNIRS analyses.

Hemodynamic profile and heart rate variability in hyperadrenergic versus non-hyperadrenergic postural orthostatic tachycardia syndrome

ObjectivesTo investigate differences in hemodynamic profile between hyperadrenergic and non-hyperadrenergic postural orthostatic tachycardia syndrome (POTS) in response to head-up tilt test (HUTT). MethodsTen patients with hyperadrenergic and 33 patients with non-hyperadrenergic POTS underwent HUTT consisting of a 10-min supine phase and 30-min 70° tilted phase. Heart rate (HR), systolic and diastolic blood pressure (dBP), and heart rate variability (HRV) parameters of the two groups were compared. ResultsHyperadrenergic patients had higher supine HR (82.6±16.3bpm vs. 73.8±10.4bpm, p=0.048). Supine HRV analysis showed significantly lower cardiac vagal activity and possible predominance of cardiac sympathetic activity in the hyperadrenergic group. Non-hyperadrenergic patients had lower dBP during the first four minutes of tilt. Furthermore, 60% of non-hyperadrenergic patients had lower average dBP in the 1st minute of tilted phase when compared to supine values, whereas only 2 of 10 hyperadrenergic patients exhibited the same response. Syncope or intolerable symptoms, causing early ending of HUTT, developed earlier in the non-hyperadrenergic group (8.9±6.8min vs. 21.2±3.5min, p=0.001). ConclusionHyperadrenergic and non-hyperadrenergic type of POTS seem to have distinctly different response to HUTT. SignificanceThis study has shown significant differences in hemodynamic response to HUTT between hyperadrenergic and non-hyperadrenergic type of POTS indicating possible differences in their pathophysiology.

Exploring diazepam's effect on hemodynamic responses of mouse brain tissue by optical spectroscopic imaging.

In this study, a simple duel-optical spectroscopic imaging apparatus capable of simultaneously determining relative changes in brain oxy-and deoxy-hemoglobin concentrations was used following administration of the anxiolytic compound diazepam in mice with strong dominant (Dom) and submissive (Sub) behavioral traits. Three month old mice (n = 30) were anesthetized and after 10 min of baseline imaging, diazepam (1.5 mg/kg) was administered and measurements were taken for 80 min. The mouse head was illuminated by white light based LED's and diffused reflected light passing through different channels, consisting of a bandpass filter and a CCD camera, respectively, was collected and analyzed to measure the hemodynamic response. This work's major findings are threefold: first, Dom and Sub animals showed statistically significant differences in hemodynamic response to diazepam administration. Secondly, diazepam was found to more strongly affect the Sub group. Thirdly, different time-series profiles were observed post-injection, which can serve as a possible marker for the groups' differentiation. To the best of our knowledge, this is the first report on the effects of an anxiolytic drug on brain hemodynamic responses in mice using diffused light optical imaging.

Safety of Atomoxetine in Combination With Intravenous Cocaine in Cocaine-Experienced Participants

Atomoxetine has been considered as an agonist replacement therapy for cocaine. We investigated the safety of the interaction of atomoxetine with cocaine and also whether cognitive function was affected by atomoxetine during short-term administration. In a double-blind placebo-controlled inpatient study of 20 cocaine-dependent volunteers, participants received atomoxetine 80 mg daily followed by 100 mg daily for 5 days each. On the fourth and fifth day at each dose, cocaine (20 and 40 mg) was infused intravenously in sequential daily sessions. Preinfusion mean systolic pressures showed a small but statistically significant difference between placebo and both doses of atomoxetine. Preinfusion mean diastolic pressures were significant between placebo and atomoxetine 80 mg only. The diastolic pressure response to 40 mg cocaine was statistically significant only between the 80- and 100-mg atomoxetine doses. All electrocardiogram parameters were unchanged. Visual Analog Scale (VAS) scores for "bad effect" in the atomoxetine group were significantly higher at baseline, then declined, and for "likely to use" declined with atomoxetine treatment. On the Addiction Research Center Inventory, the atomoxetine group scored significantly lower on amphetamine, euphoria, and energy subscales (P < 0.0001). Other VAS descriptors, Brief Substance Craving Scale, Profile of Moods State, and Brief Psychiatric Rating Scale showed no differences. Atomoxetine did not affect cocaine pharmacokinetics. In tests of working memory, sustained attention, cognitive flexibility, and decision-making, atomoxetine improved performance on the visual n-back task. There were no differences in any pharmacokinetic parameters for cocaine with atomoxetine. Atomoxetine was tolerated safely by all participants. Certain cognitive improvements and a dampening effect on VAS scores after cocaine were observed, but should be weighed against small but significant differences in hemodynamic responses after atomoxetine.

The effect of endogenous estrogen on Doppler-estimated right ventricular systolic pressure during exercise

We evaluated the effect of endogenous estrogen levels on exercise-related changes in right ventricular systolic pressure (RVSP) of healthy, eumenorrheic, sedentary women. Volunteers were studied at two separates phases of the menstrual cycle (LO and HI estrogen phases), exercised on a semi-supine ergometer with escalating workload and monitored continuously by 12-lead ECG and automated blood pressure cuff. At each exercise stage, Doppler echocardiography measurements were obtained and analyzed to determine RVSP. Fourteen subjects (age 24 ± 5) were studied. Exercise duration was significantly higher on the HI estrogen day, but no significant differences in hemodynamic response to exercise were found between the two study days. There were also no significant differences with respect to heart rate (HR) acceleration during early exercise, as well as resting and peak RVSP, HR, blood pressure, and rate pressure product. Doppler-estimated RVSP demonstrated a linear relationship to HR at a ratio of 1 mm Hg (1 mm Hg = 133.3224 Pa) for every 5 bpm (beats per minute) increase in HR. There were no differences in the slope of this relationship between HI and LO estrogen phases of the menstrual cycle. Our findings did not demonstrate any effect of endogenous estrogen levels on the modulation of the pulmonary vascular response to exercise in healthy women.

Cortical Hemodynamic Responses to Intravenous Thiamine Propyldisulphide Administration Detected by Multichannel Near Infrared Spectroscopy (NIRS) System

Intravenous injection of thiamine propyldisulphide (TPD), which induces sensation of a garlic-like odor, has been used as a representative subjective olfactory test in Japan. However, cortical loci activated by TPD still remain unclear. We recorded cerebral hemodynamic responses (changes in Oxy-Hb concentrations) induced by TPD administration using whole-head multi-channel near infrared spectroscopy (NIRS) system based on 3D-MRIs. TPD as an odorant and saline as a control were injected from the cephalic vein in the left forearm in ten male normosmic (five young and five elderly) subjects and five dysosmic elderly patients. The all normosmic, but not dysosmic, subjects felt the garlic-like odor in the all TPD trials. There was no significant difference in hemodynamic responses between the young and elderly normosmic subjects. However, TPD injection induced significantly larger hemodynamic responses in the bilateral operculums, bilateral dorsolateral prefrontal cortices (PFC) and anteromedial PFC in the normosmic subjects, compared with saline injection. Onset latencies of these hemodynamic responses were significantly correlated with onset latencies of subjective odor sensation in the normosmic subjects. Comparison of hemodynamic responses between the normosmic and dysosmic subjects indicated a significant difference in the bilateral operculums. The results demonstrated that Oxy-Hb increases in the bilateral operculums reflected olfactory sensation induced by TPD injection. Consideration of a route for intravenous TPD to reach the olfactory mucosa suggests that these hemodynamic responses might be attributed to food-related retronasal olfactory responses to TPD.

Effect of Continuous Infusion of Ketamine on the Cortisol and Hyperglycemic Response to Abdominal Surgery during General Anesthesia

Background: The effect of a continuous infusion of ketamine on the cortisol and hyperglycemic response induced by surgery was studied in patients undergoing an abdominal hysterectomy under enflurane anesthesia. Methods: Twenty adult female patients were randomly allocated to two groups receiving intravenous ketamine (0.3 mg/kg initially, followed by a continuous infusion at a rate of 0.15 mg/kg/h) (ketamine group, n = 10) or normal saline (control group, n = 10) 2 min after intubation. Hemodynamic responses, serum cortisol and glucose concentrations were measured before induction, 2 min after intubation, 2 min after incision, at closure of peritoneum and 5 min after extubation. Inspired and expired concentrations of enflurane were also evaluated. Results: There were no significant differences in hemodynamic responses, inspired and expired concentrations of enflurane, serum cortisol and glucose concentrations between the two groups. As compared with the values before induction, significant increases were seen in serum cortisol (control: 2.3-2.6 times, ketamine: 2-2.2 times) and glucose concentrations (control: 1.2-1.3 times, ketamine: 1.3 times) at closure of peritoneum and 5 min after extubation in both groups (P

AMRINONE ALONE AND COMBINED USE OF AMRINONE WITH DOBUTAMINE IMMEDIATELY AFTER CARDIOVASCULAR SURGERY

Each six patients undergoing cardiovascular surgery at the department from November 1993 to June 1994 were assigned to a group received dobutamine alone or another group received dobutamine and amrinone combinedly in an early postoperative period for the purpose of circulatory support. In this study the both groups were compared for hemodynamic response. There was no significant difference in hemodynamic responses between two groups. Amrinone, known as phosphodiesterase III inhibitor, augment the cardiac function without inclement of O2 consumption of the myocardium. The combined use of amrinone and dobutamine which have different mechanisms of action each other can be one of choices for treatment immediately after cardiovascular surgery that exerts a synergistic effect to increase the cardiac function and to decrease the dose of catecholamine.

Acute hemodynamic effects of nitroprusside in children with isolated mitral regurgitation

The acute hemodynamic responses to nitroprusside during cardiac catheterization were evaluated in 12 children with isolated mitral regurgitation (MR) of congenital origin. The patients were classified into 2 groups. Group 1 consisted of 5 patients who received digitalis or diuretic drugs and group II consisted of 7 patients who received no medication. Hemodynamic measurements were performed using a multisensor catheter system during infusion of nitroprusside at a dose of 2.0 μg/kg/min. With nitroprusside, the mean right atrial pressure decreased an average of 50% in group I (from 6 ± 1 to 3 ± 1 mm Hg) and 75% in group II (from 4 ± 1 to 1 ± 1 mm Hg), and the mean decrease of pulmonary artery wedge pressure was 50% in group I (from 14 ± 3 to 7 ± 3 mm Hg) and 56% in group II (from 9 ± 2 to 4 ± 1 mm Hg). Administration of nitroprusside also caused a significant reduction in systemic vascular resistance by 40% in both groups (from 25 ± 6 to 15 ± U/m 2 in group I and from 25 ± 2 to 15 ± 3 U/m 2 in group II), whereas forward cardiac output increased markedly, by an average of 48% in group I (from 3.3 ± 0.5 to 4.9 ± 0.9 liters/min/m 2) and 58% in group II (from 3.3 ± 0.3 to 5.2 ± o.8 liters/min/m 2). No significant differences in hemodynamic response between groups I and II were noted. These data indicate that nitroprusside augments forward ejection associated with decrease in regurgitant flow as a results of reductions in preload and afterload regardless of the severity of MR. It is concluded that vasodilator therapy may be beneficial for selected infants and children with MR.

Comparison of hemodynamic responses to nifedipine and nitroprusside in severe chronic congestive heart failure

The hemodynamic effects of 20 to 40 mg of oral nifedipine were compared with those of intravenous nitroprusside in 11 patients with severe chronic congestive heart failure (CHF). In each patient, both drugs were administered to produce similar reduction of systemic vascular resistance (SVR) (29 ± 13% with nifedipine and 29 ± 12% with nitroprusside, difference not significant [NS]). At this comparable decrease in systemic vascular resistance, significant differences in hemodynamic responses to both drugs were noted: Nifedipine caused a smaller increase in cardiac index (20 ± 20% vs 40 ± 24%, p < 0.02) and a larger decrease in mean blood pressure than nitroprusside (16 ± 9% vs 8 ± 10%, p < 0.05). In addition, nifedipine produced a smaller decrease in mean pulmonary artery wedge pressure (13 ± 24% vs 36 ± 21%, p < 0.001) and pulmonary vascular resistance than nitroprusside (6 ± 42% vs 26 ± 46%, NS. Mean right atrial pressure decreased with nitroprusside, from 10 ± 7 to 5 ± 3 mm Hg (p < 0.05), but not with nifedipine (10 ± 7 mm Hg before and after nifedipine administration, NS). Left ventricular stroke work index increased with nitroprusside (20 ± 8 to 27 ± 9 g- m/ m 2, p < 0.05), but did not change with nifedipine (21 ± 9 vs 21 ± 10 g- m/ m 2, NS). These data show that nifedipine has an arteriolar dilatatory action in patients with CHF. However, compared with nitroprusside, nifedipine had a significantly larger hypotensive effect and had a lesser effect on right and left ventricular filling pressure, cardiac output and left ventricular function.

Prolonged feeding of ethanol to the young growing guinea pig. II. A model to study the effects of severe ischemia on cardiac protein synthesis.

Although acute perfusion of guinea pig hearts with ethanol does not affect cardiac protein synthesis, the latter is inhibited after prolonged ingestion of ethanol when tested in an in vitro system with the working right ventricle. This study reports on the added stress of ischemia on such hearts. Hearts were removed from maturing guinea pigs after 13-16 weeks of ingesting 10% ethanol and were perfused in vitro under conditions of relative ischemia (one-sixth of normal coronary flow) with maintenance of right ventricular load and outflow resistance identical to normal pre-ischemic levels. With this degree of ischemia, there was a 4-6 fold increase in lactate production, an 80% drop in ATP, and a 90% decrease in creatine phosphate after 150 min of the ischemia. Incorporation of both labeled lysine and phenylalanine into cardiac protein was also diminished to 35% of control in the left ventricle and 55% of control in the right. This diminution of protein synthesis was the same in hearts from ethanol-drinking and matched control animals. Thus, prior prolonged ingestion of ethanol did not worsen the inhibition of protein synthesis by oxygen deprivation. There were, however, two significant differences in hemodynamic response to the ischemia by the right ventricles of hearts from ethanol-drinking guinea pigs compared to their matched controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocardial Metabolism and Hemodynamic Responses to Halothane or Morphine Anesthesia for Coronary Artery Surgery

Eighteen patients having coronary artery bypass grafts were randomly anesthetized with morphine (1 mg/kg) or halothane and oxygen. Central and peripheral pressures were measured serially, plus cardiac output and total coronary sinus blood flow, both by thermodilution catheters, starting before induction of anesthesia and continuing until completion of sternotomy. No significant differences in hemodynamic responses were seen between the two anesthetic techniques during induction: blood pressure and peripheral vascular resistance decreased significantly, but not cardiac output or coronary flow. Myocardial oxygen consumption decreased significantly with induction as oxygen content of coronary sinus blood increased, indicating preservation of oxygen balance. Heart rate and blood pressure increased after sternotomy in the patients given morphine, with the myocardium producing lactate in two of six patients and with nitroprusside being required in four patients to decrease arterial pressure. Halothane-oxygen anesthesia effectively controlled autonomic responses to sternotomy, although one of 12 patients had myocardial lactate production at that time. Neither rate-pressure product or ST segment changes were useful predictors of the ratio between myocardial oxygen consumption and supply. Myocardial oxygen balance can be maintained in coronary patients before cardiopulmonary bypass if pulse rate and blood pressure are kept at less than awake levels.

Myocardial Metabolism and Hemodynamic Responses to Halothane or Morphine Anesthesia for Coronary Artery Surgery

Eighteen patients having coronary artery bypass grafts were randomly anesthetized with morphine (1 mg/kg) or halothane and oxygen. Central and peripheral pressures were measured serially, plus cardiac output and total coronary sinus blood flow, both by thermodilution catheters, starting before induction of anesthesia and continuing until completion of sternotomy. No significant differences in hemodynamic responses were seen between the two anesthetic techniques during induction: blood pressure and peripheral vascular resistance decreased significantly, but not cardiac output or coronary flow. Myocardial oxygen consumption decreased significantly with induction as oxygen content of coronary sinus blood increased, indicating preservation of oxygen balance. Heart rate and blood pressure increased after sternotomy in the patients given morphine, with the myocardium producing lactate in two of six patients and with nitroprusside being required in four patients to decrease arterial pressure. Halothane-oxygen anesthesia effectively controlled autonomic responses to sternotomy, although one of 12 patients had myocardial lactate production at that time. Neither rate-pressure product or ST segment changes were useful predictors of the ratio between myocardial oxygen consumption and supply. Myocardial oxygen balance can be maintained in coronary patients before cardiopulmonary bypass if pulse rate and blood pressure are kept at less than awake levels.