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Biomedical subjects

R F Brooker

Publications and source records attributed to R F Brooker.

At least 19 recordsLinked to original sources
PubMed2001

Do pulmonary artery catheters cause or increase tricuspid or pulmonic valvular regurgitation?

UNLABELLED: There are few quantitative data on the extent or mechanism of pulmonary artery catheter (PAC)-induced valvular dysfunction. We hypothesized that PACs cause or worsen tricuspid and pulmonic valvular regurgitation, and tested this hypothesis by using transesophageal echocardiography. In 54 anesthetized adult patients, we measured color Doppler jet areas of tricuspid regurgitation (TR) in two planes (midesophageal [ME] 4-chamber and right ventricular inflow-outflow views) and pulmonic insufficiency (PI) in one plane (ME aortic valve long-axis view), both before and after we advanced a PAC into the pulmonary artery. Regurgitant jet areas and hemodynamic measurements were compared by using paired t-test. There were no significant changes in blood pressure or heart rate after passage of the PAC. After PAC placement, the mean PI jet area was not significantly increased. The mean TR jet area increased significantly in the right ventricular inflow-outflow view (+0.37 +/- 0.11 cm(2)) (P = 0.0014), but did not increase at the ME 4-chamber view. Seventeen percent of patients had an increase in TR jet area > or =1 cm(2); 8% of patients had an increase in PI jet area >/=1 cm(2). IMPLICATIONS: In patients without pulmonic or tricuspid valvular pathology, placement of a pulmonary artery catheter (PAC) worsened tricuspid regurgitation, which is consistently visualized in the right ventricular inflow-outflow view, and often not seen in the midesophageal 4-chamber view. This is consistent with malcoaptation of the anterior and posterior leaflets. PAC-induced pulmonic insufficiency was rarely detected in the midesophageal aortic valve long-axis view. We conclude that a PAC is very unlikely to be the sole cause of severe tricuspid regurgitation or pulmonic insufficiency.

Aged↗
PubMed1998

Three-dimensional surface area of the aortic valve orifice by three-dimensional echocardiography: clinical validation of a novel index for assessment of aortic stenosis.

BACKGROUND: A direct and accurate method of assessing aortic valve area (AVA) in patients with aortic stenosis (AS) is desirable because of the well-known theoretical and practical limitations of the currently available methods. We assessed the clinical feasibility and accuracy of a novel index, the 3-dimensional surface area (3-DSA) of the aortic valve orifice by 3-dimensional transesophageal echocardiography (3-DTEE) in patients with AS. METHODS: Intraoperative 3-DTEE was performed in 23 consecutive patients (mean age 58 +/- 15 years) with valvular AS using a Toshiba SSA-380A system with a multiplane TEE probe and a TomTec EchoScan system. The 3-DTEE acquisition, processing and reconstruction were conducted and the aortic valve orifice presented using a "surgeon's aortotomy view" (aortic valve orifice as if viewed through an open aortic root). The 3-D images were videotaped and calibrated and the 3-DSA measured by planimetry of the inner surface of the aortic valve leaflets at the maximal systolic opening using the dynamic 3-D images. For comparison, the 2-D cross sectional area (2-DCSA) of the aortic valve was also determined by 2-DTEE. The 3-DSA and 2-DCSA were compared with the AVA by the invasive Gorlin formula and the Doppler continuity equation method by transthoracic echocardiography. RESULTS: The 3-DSA and 2-DCSA measurements were feasible in all but one patient. Both 3-DSA and 2-DCSA correlated moderately well with the AVA by the Gorlin formula (n = 17, r = 0.66, standard error of the estimate [SEE] = 0.3 cm2, P <.05 for 3-DSA and r = 0.61, SEE = 0. 5 cm2 P <.05 for 2-DCSA, respectively). They also correlated well with the AVA by Doppler continuity equation method (n = 22, r = 0.90, SEE = 0.1 cm2, P <.05 for 3-DSA and r = 0.83, SEE = 0.3 cm2, P <.05 for 2-DCSA, respectively). There was no statistically significant difference between the 3-DSA and AVA by both the Gorlin formula (Delta = 0.1 +/- 0.3 cm2, P =.3) and the Doppler continuity equation (Delta = -0.0 +/- 0.3 cm2, P =.7). In contrast, the 2-DCSA significantly overestimated AVA by the Gorlin formula (Delta = 0.5 +/- 0.5 cm2, P <.005) and by the Doppler continuity equation (Delta = 0.5 +/- 0.6 cm2, P <.0001). CONCLUSIONS: Planimetry of 3-DSA of the aortic valve orifice by 3-DTEE is a clinically feasible and relatively accurate technique for assessment of AVA and is superior to 2-DCSA by 2-DTEE.

Adult↗
PubMed1998

Cardiotomy suction: a major source of brain lipid emboli during cardiopulmonary bypass.

BACKGROUND: Brain injury remains a significant problem in patients undergoing cardiac surgery assisted by cardiopulmonary bypass (CPB). Autopsy brain specimens of patients after cardiac operations with CPB reveal numerous acellular lipid deposits (10 to 70 microm) in the microvasculature. We hypothesize that these small capillary and arterial dilatations result from a diffuse inflammatory response to CPB or from emboli delivered by the bypass circuit. This study was undertaken to determine which aspect of CPB is most clearly associated with these dilatations. METHODS: Thirteen dogs were studied in four groups: group I (n = 3), right-heart CPB; group II (n = 2), lower-extremity CPB; group III (n = 3), hypothermic CPB; and group IV (n = 5), hypothermic CPB with cardiotomy suction. All dogs in all groups were maintained on CPB for 60 minutes and then euthanized. Brain specimens were harvested, fixed in ethanol, embedded in celloidin, and stained with the alkaline phosphate histochemical technique so that dilatations could be counted. RESULTS: All dogs completed the protocol. The mean density of dilatations per square centimeter for each group was as follows: group I, 1.77 +/- 0.77; group II, 4.17 +/- 1.65; group III, 4.54 +/- 1.69; and group IV, 46.5 +/- 14.5. In group IV (cardiotomy suction), dilatation density was significantly higher than in group III (hypothermic cardiopulmonary bypass) (p = 0.04) and all other groups (p = 0.04). CONCLUSIONS: Blood aspirated from the surgical field and subsequently reinfused into dogs undergoing CPB produces a greater density of small capillary and arterial dilatations than CPB without cardiotomy suction, presumably because of lipid microembolization.

Alkaline Phosphatase↗
PubMed1997

Feasibility, accuracy, and incremental value of intraoperative three-dimensional transesophageal echocardiography in valve surgery.

In this prospective trial, intraoperative 2-dimensional (2-D) and 3-dimensional (3-D) transesophageal echocardiography (TEE) examinations were performed on 60 consecutive patients undergoing cardiac valve surgery. Both 2-D (including color flow and Doppler data) and 3-D images were reviewed by blinded observers, and major valvular morphologic findings recorded. In vivo morphologic findings were noted by the surgeon and all explanted valves underwent detailed pathologic examination. To test reproducibility, 6 patients also underwent 3-D TEE 1 day before surgery. A total of 132 of 145 attempted acquisitions (91%) were completed with a mean acquisition time of 2.8 +/- 0.2 minutes. Acquisition time was significantly shorter in patients with regular rhythms. Reconstructions were completed in 121 of 132 scans (92%) and there was at least 1 good reconstruction in 56 of 60 patients (93%). Mean reconstruction time was 8.6 +/- 0.7 minutes. Mean effective 3-D time, which was the time taken to complete an acquisition and a clinically interpretable reconstruction, was 12.2 +/- 0.8 minutes. Intraoperative 3-D echocardiography was clinically feasible in 52 patients (87%). Three-D echocardiography detected most of the major valvular morphologic abnormalities, particularly leaflet perforations, fenestrations, and masses, confirmed on pathologic examination. Three-D echocardiography predicted all salient pathologic findings in 47 patients (84%) with good quality images. In addition, in 15 patients (25%), 3-D echocardiography provided new additional information not provided by 2-D echocardiography, and in 1 case, 3-D echocardiographic findings resulted in a surgeon's decision to perform valve repair rather than replacement. In several instances, 3-D echocardiography provided complementary morphologic information that explained the mechanism of abnormalities seen on 2-D and color flow imaging. In the reproducibility subset, preoperative and intraoperative 3-D imaging detected a similar number of findings when compared with pathology. Thus, in routine clinical intraoperative settings, 3-dimensional TEE is feasible, accurately predicts valve morphology, and provides additional and complementary valvular morphologic information compared with conventional 2-D TEE, and is probably reproducible.

Adolescent↗
PubMed1997

Risk factors and solutions for the development of neurobehavioral changes after coronary artery bypass grafting.

BACKGROUND: As operative mortality for coronary artery bypass grafting has decreased, greater attention has focused on neurobehavioral complications of coronary artery bypass grafting and cardiopulmonary bypass. METHODS: To assess risk factors and to evaluate changes in surgical technique, between 1991 and 1994 we evaluated 395 patients undergoing coronary artery bypass grafting with an 11-part neurobehavioral battery administered preoperatively and at 1 and 6 weeks postoperatively. Patients were instrumented with 5-MHz focused continuous-wave carotid Doppler transducers intraoperatively to estimate cerebral microembolism as an instantaneous perturbation of the velocity signal. Microembolism data were quantitated and compared with surgical technical maneuvers during operation and with neurobehavioral deficit (> or = 20% decline from preoperative performance on two or more neurobehavioral tests) postoperatively. These data and patient demographics were statistically analyzed (chi2, t test) and the results at 2 years (1991 and 1992; group A) were used to influence surgical technique in 1993 and 1994 (group B). RESULTS: Significantly associated with new neurobehavioral deficits were increasing patient age (p < 0.05), more than 100 emboli per case (p < 0.04), and palpable aortic plaque (p < 0.02). Group B patients had a significant decline in the neurobehavioral event rate (group A, 69%, 140/203; versus group B, 60%, 115/192; p < 0.05) of postoperative neurobehavioral deficits at 1 week and at 1 month (group A, 29%, 52/180; versus group B, 18%, 35/198; p < 0.01). The stroke rate was less than 2% in both groups (p = not significant). Modifications of surgical technique used in group B patients included increased use of single cross-clamp technique, increased venting of the left ventricle, and application of transesophageal and epiaortic ultrasound scanning to locate and avoid trauma to aortic atherosclerotic plaques. CONCLUSIONS: Neurobehavioral changes after coronary artery bypass grafting are common and associated with cerebral microembolization. Surgical technical maneuvers designed to reduce emboli production may improve neurobehavioral outcome.

Aged↗
PubMed1997

Morphology and dynamic change of discrete subaortic stenosis can be imaged and quantified with three-dimensional transesophageal echocardiography.

This report describes three-dimensional transesophageal echocardiographic findings in three consecutive patients with discrete subaortic stenosis. The discrete subaortic stenosis lesions included a circumferential, a remnant crescent, and a broken fibrotic subaortic membrane. The lesions were best imaged by using a three-dimensional transesophageal echocardiography-generated "aortotomy view" of the left ventricular outflow tract immediately below the plane of the aortic valve. The three-dimensional images correlated well with surgical and pathologic findings. The three-dimensional surface areas of the left ventricular outflow tract at the level of discrete subaortic stenosis during systole (0.8 +/- 0.5 cm2) and diastole (1.7 +/- 0.7 cm2) were measured by planimetry of the three-dimensional transesophageal echocardiographic images. The novel "aortotomy view" offered by three-dimensional transesophageal echocardiography provided direct visualization and quantification of discrete subaortic stenosis in a dynamic fashion. In summary, three-dimensional transesophageal echocardiography can accurately display and quantify discrete subaortic stenosis and could be a new clinically useful tool for assessing discrete subaortic stenosis and guiding surgical and transcatheter interventions.

Adult↗
PubMed1997

Topical ice slurry prevents brain rewarming during deep hypothermic circulatory arrest in newborn sheep.

OBJECTIVES: To measure the effect of ice slurry topical cooling on brain surface temperature during deep hypothermic circulatory arrest. DESIGN: This was a prospective, controlled experiment. SETTING: Animal laboratory at a university hospital. PARTICIPANTS: Five control lambs, five treatment (ice slurry) lambs. INTERVENTIONS: Animals were studied in two groups: the study group had topical cooling of the head with ice slurry started immediately before circulatory arrest and continued throughout the period of circulatory arrest; control group lambs received no supplemental topical cooling. MEASUREMENTS AND MAIN RESULTS: Brain surface temperature, scalp, nasopharyngeal, and rectal temperatures were measured at 5-minute intervals during 45 minutes of circulatory arrest. Lambs receiving topical cooling of the head with ice slurry had a statistically significant decrease in brain surface temperature of 2.2 +/- 1.2 degrees C during circulatory arrest, whereas brain surface temperature increased 1.2 +/- 0.3 degrees C, in control lambs. Equilibration of temperature between the scalp and brain in control lambs produced rewarming of the brain surface. CONCLUSIONS: Topical cooling of the head with ice slurry in newborn lambs lowers brain surface temperature during deep hypothermic circulatory arrest. Surrogate temperature monitoring locations such as nasopharyngeal and rectal temperatures varied significantly and do not accurately reflect changes in brain surface temperature.

Animals↗
PubMed1997

Treatment of hypotension after hyperbaric tetracaine spinal anesthesia. A randomized, double-blind, cross-over comparison of phenylephrine and epinephrine.

BACKGROUND: Despite many advantages, spinal anesthesia often is followed by undesirable decreases in blood pressure, for which the ideal treatment remains controversial. Because spinal anesthesia-induced sympathectomy and management with a pure alpha-adrenergic agonist can separately lead to bradycardia, the authors hypothesized that epinephrine, a mixed alpha- and beta-adrenergic agonist, would more effectively restore arterial blood pressure and cardiac output after spinal anesthesia than phenylephrine, a pure alpha-adrenergic agonist. METHODS: Using a prospective, double-blind, randomized, cross-over study design, 13 patients received sequential infusions of epinephrine and phenylephrine to manage hypotension after hyperbaric tetracaine (10 mg) spinal anesthesia. Blood pressure, heart rate, and stroke volume (measured by Doppler echocardiography using the transmitral time-velocity integral) were recorded at baseline, 5 min after injection of tetracaine, and before and after management of hypotension with epinephrine and phenylephrine. Cardiac output was calculated by multiplying stroke volume x heart rate. RESULTS: Five min after placement of a hyperbaric tetracaine spinal anesthesia, significant decrease in systolic (from 143 +/- 6 mmHg to 125 +/- 5 mmHg; P < 0.001), diastolic (from 81 +/- 3 to 71 +/- 3; P < 0.001), and mean (from 102 +/- 4 to 89 +/- 3; P < 0.001) arterial pressures occurred. Heart rate (75 +/- 4 beats/min to 76 +/- 4 beat/min; P = 0.9), stroke volume (115 +/- 17 to 113 +/- 13; P = 0.9), and cardiac output (8.0 +/- 1 l/m to 8.0 +/- 1l/m; P = 0.8) did not change significantly after spinal anesthesia. Phenylephrine was effective at restoring systolic blood pressure after spinal anesthesia (120 +/- 6 mmHg to 144 +/- 5 mmHg; P < 0.001) but was associated with a decrease in heart rate from 80 +/- 5 beats/min to 60 +/- 4 beats/min (P < 0.001) and in cardiac output from 8.6 +/- 0.7 l/m to 6.2 +/- 0.7 l/m (P < 0.003). Epinephrine was effective at restoring systolic blood pressure after spinal anesthesia (119 +/- 5 mmHg to 139 +/- 6 mmHg; P < 0.001) and was associated with an increase in stroke volume from 114 +/- 12 ml to 142 +/- 17 (P < 0.001) and cardiac output from 7.8 +/- 0.6 l/m to 10.8 +/- 1.1 l/m (P < 0.001). CONCLUSIONS: Epinephrine management of tetracaine spinal-induced hypotension increases heart rate and cardiac output and restores systolic arterial pressure but does not restore mean and diastolic blood pressure. Phenylephrine management of tetracaine spinal-induced hypotension decreases heart rate and cardiac output while restoring systolic, mean, and diastolic blood pressure.

Adrenergic Agonists↗
PubMed1997

The effect of esmolol on ST-segment depression and arrhythmias after electroconvulsive therapy.

Electroconvulsive therapy (ECT) induces sympathetically mediated hemodynamic alterations that can be associated with myocardial ischemia and arrhythmia generation. Esmolol, a short-acting beta-blocker, blunts the hypertension and tachycardia seen with ECT. The purpose of this study is to determine whether esmolol use during ECT reduces the incidence of myocardial ischemia or arrhythmias after ECT. In a randomized, double-blind, placebo-controlled protocol, with each patient acting as his/her own control, the effects of esmolol on the incidence of myocardial ischemia and arrhythmias were studied using two-lead Holter monitoring for at least 2 h post-ECT. Nineteen patients underwent 71 ECT treatments (34 placebo, 37 esmolol), recording 746 h of Holter data. The esmolol group had significantly reduced heart rate and mean arterial pressure immediately after ECT. There was no difference in the incidence of ECG defined ischemia post-ECT between groups, with 7 of 19 (36.8%) patients in the esmolol group showing ST-segment depression compared with 5 of 19 (26.3%) in the placebo group. There was no difference between groups in arrhythmia detection. This experiment demonstrates that (a) ECT is associated with a significant incidence of ST-segment depression, (b) esmolol blunts the sympathetic discharge during ECT, and (c) esmolol does not reduce the incidence of post-ECT ischemia or arrhythmia.

Adrenergic beta-Antagonists↗
PubMed1996

The importance of the postoperative anesthetic visit: do repeated visits improve patient satisfaction or physician recognition?

This study evaluates whether repeated postoperative visits by the anesthesiologist improve patient ability to recall the anesthesiologist's name and the patient's perception of and satisfaction with anesthesia services. In a randomized, prospective trial, 144 patients with an anticipated postoperative length of stay of at least three days were enrolled in three groups: Group A patients (n = 48) had one postoperative visit, Group B (n = 48) had two postoperative visits, and Group C (n = 48) had three postoperative visits. All postoperative visits were performed by the attending anesthesiologist on consecutive postoperative days. Patients were contacted two days after their last postoperative visit to complete a study questionnaire. Patients were able to recall the anesthesiologist's name significantly less frequently than the surgeon's name, and there was no difference in name recall among groups. Recall was not affected by patient age, sex, or ASA physical status; the mode of contact (telephone versus personal visit); the anesthesiologist's gender; the presence of preoperative medication; or the identity of the preoperative evaluator. Patients could identify the anesthesiologist's gender approximately 85% of the time, regardless of group, and were more likely to identify female anesthesiologists (P = 0.026, odds ratio 3.3). Patient evaluation of hospital, surgical, and anesthesia care was favorable in all groups and did not vary with group. Increasing the number of postoperative visits does not improve patient name recognition of the anesthesiologist or increase patient satisfaction with or perception of anesthesia services.

Age Factors↗
PubMed1993

Hemodynamic and pharmacodynamic comparison of doxacurium and pipecuronium with pancuronium during induction of cardiac anesthesia: does the benefit justify the cost?

We compared the pharmacodynamic effects and hospital costs of three long-acting neuromuscular blocking drugs in a prospective, randomized, double-blind manner. Each neuromuscular blocking drug was administered with fentanyl (50 micrograms/kg) for intravenous induction of anesthesia for coronary artery bypass surgery. Each patient received twice the 95% effective dose (ED95) of either pancuronium (0.14 mg/kg, n = 10), pipecuronium (0.10 mg/kg, n = 10), or doxacurium (0.05 mg/kg, n = 10). Hemodynamic measurements were recorded at baseline, 5 min after completion of anesthetic induction, immediately after endotracheal intubation, and 5 min after intubation. Only small hemodynamic differences between neuromuscular blocking drugs were observed. Doxacurium (but not pancuronium or pipecuronium) significantly decreased mean arterial blood pressure (from 94 +/- 4 mm Hg before induction to 83 +/- 3 mm Hg 5 min after intubation); nevertheless, there were no significant between-group differences at any time. Pancuronium increased heart rate (from 68 +/- 4 beats/min before induction to 76 +/- 5 beats/min 5 min after intubation); however, pancuronium differed significantly from doxacurium and pipecuronium only 5 min after induction and 5 min after intubation. Central venous pressure, pulmonary artery occlusion pressure, cardiac index, and systemic and pulmonary vascular resistance indices did not change. Electrocardiographic abnormalities were observed in two pipecuronium patients: ST segment depression in one and premature ventricular contractions in another. No other electrocardiographic changes were observed. There were no significant between-group differences in the need for hemodynamic interventions.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Intravenous↗