Search PubMed⌕ Search

Biomedical subjects

D L Reich

Publications and source records attributed to D L Reich.

At least 37 records · Page 2Linked to original sources
PubMed1998

Comparison of the cardiovascular effects of cisatracurium and vecuronium in patients with coronary artery disease.

PURPOSE: Cisatracurium besylate (Nimbex Injection, Glaxo Wellcome Inc., Research Triangle Park, NC) is an intermediate-acting bis-benzylisoquinolinium neuromuscular blocking drug that is one of the stereoisomers of atracurium. At doses < or = 8 x ED95, it caused no clinically important cardiovascular side effects or histamine release in healthy patients. The purpose of the present study was to investigate the haemodynamic effects of high doses of cisatracurium in patients with coronary artery disease. METHODS: One hundred patients undergoing myocardial revascularization participated in a pilot study (seven patients) and a double-blinded, randomized, controlled trial comparing the haemodynamic effects of cisatracurium with vecuronium at three centres. The patients were anaesthetized using oxygen 100%, with etomidate, fentanyl and a benzodiazepine, and tracheal intubation was facilitated using succinylcholine. After baseline haemodynamic measurements, the study drug was administered over 5-10 sec according to group assignment: Group A (pilot) cisatracurium, 0.20 mg.kg-1 (4 x ED95), (n = 7); Group B-cisatracurium, 0.30 mg.kg-1 (6 x ED95), (n x ED95), (n = 31); Group C-vecuronium, 0.30 mg.kg-1 (6 x ED95), (n = 31); Group D cisatracurium, 0.40 mg.kg-1 (8 x ED95), (n = 21); Group E-vecuronium, 0.30 mg.kg-1 (6 x ED95), (n = 10). The haemodynamic measurements were repeated at 2, 5, and 10 min after cisatracurium or vecuronium. RESULTS: Two patients in Group D had > 20% decreases in MAP, but only one required therapy for hypotension. The haemodynamic changes from pre- to post-injection in the cisatracurium patients were minimal and similar to patients receiving vecuronium. CONCLUSIONS: In patients with coronary artery disease, rapid cisatracurium (4-8 x ED95) boluses and vecuronium (6 x ED95) result in minor, clinically insignificant haemodynamic side effects.

Atracurium↗
PubMed1998

Expert systems in anesthesiology.

There are only a limited number of computer-based systems designed to support anesthesiologists in the operating room. This is evident from the very small number of publications on this topic. These systems may be classified by the functions they perform and include: intelligent anesthesia workstations (with current data acquisition, conditioning and analysis subsystems), systems to detect critical conditions in patients (including expert systems in smart alarm capacity), anesthesia management systems (for planning and management) and drug administration systems. Drug administration systems may be subdivided into open-loop and closed-loop systems. The techniques applied for design of such systems vary extensively. There are traditional rule-based expert systems and probability-based systems, and more recently developed artificial intelligence methods, such as neural networks and fuzzy logic. Computers are valuable tools that have the potential to assist anesthesiologists in carrying out cumbersome and monotonous processes. Future efforts may result in the development of sophisticated systems capable of assuming more responsibilities and of reducing human workload and stress.

Journal Article↗
PubMed1997

An algorithm for assessing intraoperative mean arterial pressure lability.

BACKGROUND: Intraoperative blood pressure lability may be related to risk factors, hypovolemia, light anesthesia, and morbid outcomes, but the measurements of lability in previous studies have been limited by imprecise and infrequent data collection methods. Computerized intraoperative data acquisition systems have provided an opportunity to readdress the issue of intraoperative blood pressure lability with more abundant and precise data. This study sought to derive and validate an algorithm (expert system) to measure mean arterial pressure (MAP) lability. METHODS: Two hundred thirty-nine computerized anesthesis records were reviewed retrospectively. Three anesthesiologists separately rated MAP as very stable, average, or very labile. The parameters of a computer algorithm that measured the change of median MAP between consecutive 2-min epochs were optimized to achieve the best possible agreement among the anesthesiologists. The algorithm was then validated on 229 additional anesthesia records. RESULTS: The proportion of consecutive 2-min epochs in which the absolute value of the fractional change of median MAP exceeded 0.06 (i.e., 6%) correlated strongly with the anesthesiologists' ratings (r = 0.78; P < 0.0001). The optimal sensitivity and specificity of the algorithm for detecting MAP lability were 98% and 59%, respectively. CONCLUSIONS: One potential application of expert systems to anesthesia practice is a "smart alarm" to detect blood pressure lability. It may also provide a better tool to assess the relation between lability and outcome than has been available previously.

Algorithms↗
PubMed1996

Validation of a test of competence in transesophageal echocardiography.

OBJECTIVE: A test was developed that is based on intraoperative findings to evaluate knowledge of intraoperative echocardiography. This study examines the performance of attending anesthesiologists and residents at various levels of training in order to validate the test's ability to measure physician competence in intraoperative echocardiographic diagnosis. DESIGN: This study was a prospective evaluation of a test of competence in transesophageal echocardiography. SETTING: Two university medical centers. PARTICIPANTS: Volunteer anesthesia faculty and residents. INTERVENTIONS: The participants took an echocardiographic examination that consisted of 34 "K"-type multiple-choice questions and a 45-second video-loop sequence for each question. The video sequences were chosen for their high quality and unambiguous representation of both normal and pathologic images obtained by transverse transesophageal echocardiographic imaging. The questions were written by experienced echocardiographers. The test was administered to 25 individuals at two academic institutions: 11 residents with minimal transesophageal echocardiography exposure and 14 faculty who were relatively experienced with transesophageal echocardiography. All of the residents repeated the examination at the end of their third clinical anesthesia year, which included transesophageal echocardiography training. The differences between the groups' scores were analyzed using the Kruskal-Wallis test and Wilcoxon's rank-sum test. To correct for the multiple comparisons, p < 0.025 was deemed significant. MEASUREMENTS AND MAIN RESULTS. Before their transesophageal echocardiography training, the residents scored significantly lower than the faculty (p < 0.002). After 1 year of training, their scores significantly increased (p = 0.021), and their scores were not significantly different from the faculty level (p = 0.052). CONCLUSIONS: Test performance differed according to level of experience. This suggests that the test is a valid measure of intraoperative transesophageal echocardiography competence.

Anesthesiology↗
PubMed1996

Tranexamic acid reduces transfusions and mediastinal drainage in repeat cardiac surgery.

The administration of tranexamic acid (TA) prior to cardiopulmonary bypass (CPB) has been associated with reduced bleeding during and after cardiac surgery. In a prospective, randomized, controlled, double-blind clinical trial, adult patients undergoing repeat open heart surgery received TA (n = 17) or an equal volume of saline placebo (n = 13). In the TA group, a 20-mg/kg intravenous (IV) initial dose of TA at akin incision was followed by an infusion of 2 mg.kg-1.h-1, which continued for the duration of the surgical procedure. Identical transfusion guidelines were followed in both groups. Routine coagulation tests, D-dimer levels, mediastinal tube drainage, and transfusion requirements were compared. Cumulative postoperative mediastinal tube drainage measured at 24 h was 649 +/- 391 mliter (mean +/- SD) in the TA group compared with 923 +/- 496 mliter in the placebo group (P < 0.01). Forty-eight-and 72-h mediastinal tube drainage were also significantly less in the TA group (P < 0.01). Seven of 17 TA patients received to transfusion of allogeneic blood products compared with 1 of 13 placebo patients (P = 0.047). The incidence and volumes of platelet and fresh frozen plasma transfusion in the TA group were not significantly different in comparison with the placebo group. The perioperative increase in D-dimer levels (post-CPB minus pre-CPB) in the placebo group (median difference = 675 ng/mliter, range 125-1648) was significantly more than in the TA group (median difference = 182 ng/mliter, range -426-1950; P = 0.003). Sternal closure occurred in 41 +/- 21 min in the TA group and 61 +/- 49 min in the placebo group (P = 0.14), and the subjective bleeding score was less in the TA group than in the placebo group (2.38 +/- 0.78 vs 3.08 +/- 1.04; P = 0.045). The data from the current study support the prophylactic use of TA in patients undergoing repeat cardiac surgery. TA administered prior to CPB reduced the incidence of allogeneic transfusions and postoperative mediastinal tube drainage, and improved the subjective assessment of post-CPB hemostasis in a group of patients at moderately high risk for perioperative bleeding.

Adult↗
PubMed1996

Predictors of pulse oximetry data failure.

BACKGROUND: Pulse oximeters have been reported to fail to record data in 1.12-2.50% of cases in which anesthesia records were handwritten. There is reason to believe that these may be underestimates. Computerized anesthesia records may provide insight into the true incidence of pulse oximetry data failures and factors that are associated with such failures. METHODS: The current study reviewed case files of 9,203 computerized anesthesia records. Pulse oximetry data failure was defined as the presence of at least one continuous gap in data > or = 10 min in duration in a case. A multivariate logistic regression model was used to identify predictors of pulse oximetry data failure, and a modified case-control method was used to determine whether extremes of blood pressure and hypothermia during the procedure were associated with pulse oximetry data failure. RESULTS: The overall incidence of cases that had at least one continuous gap of > or = 10 min in pulse oximetry data was 9.18%. The independent preoperative predictors of pulse oximetry data failure were ASA physical status 3,4, or 5 and orthopedic, vascular, and cardiac surgery. Intraoperative hypothermia, hypotension, hypertension, and duration of procedure were also independent risk factors for pulse oximetry data failure. CONCLUSIONS: Pulse oximetry data failure rates based on review of computerized records were markedly greater than those previously reported. Physical status, type of surgery, and intraoperative variables were risk factors for pulse oximetry data failure. Regulations and expectations regarding pulse oximetry monitoring should reflect the limitations of the technology.

Humans↗
PubMed1995

Cardiopulmonary bypass for adult patients: a survey of equipment and techniques.

OBJECTIVES: The techniques and equipment used for cardiopulmonary bypass for adult cardiac surgery vary among institutions and may change over time. This study sought to document the changing patterns of practice. DESIGN: Voluntary survey of meeting participants. SETTING: 13th Annual San Diego Cardiothoracic Surgery Symposium (February 1993). PARTICIPANTS: There were 331 responses from perfusionists (79.5%), cardiac surgeons (11.2%), and anesthesiologists (6.3%). The majority of these participants were from institutions where more than 1,000 cardiac operations were performed annually. MEASUREMENTS AND MAIN RESULTS: It was found that 91.5% of the respondents used membrane oxygenators currently, compared with 5% in 1982 (as reported in a previous survey). Over 80% of the institutions surveyed used some type of perioperative cell-salvaging technique. Arterial line filters were used by 92% of the respondents compared with 64% in 1982. Also, 80% of the respondents were aware of the availability of leukocyte-depleting filters. CONCLUSIONS: The probable reasons for the increased utilization of membrane oxygenators and arterial line filters include less damage to the formed elements of blood, fewer gaseous microemboli, and better control of carbon dioxide elimination and oxygenation. The authors anticipate that future surveys will document increased use of leukocyte-depleting filters because of the literature implicating neutrophils as mediators of tissue destruction in various disease processes, including myocardial reperfusion injury.

Adult↗
PubMed1995

Nitric oxide modulates dopamine release during global temporary cerebral ischemia.

Dopamine (DA) is released in large quantities from the striatum during cerebral ischemia. Along with excitatory neurotransmitters, DA plays a role in cellular neuronal ischemic injury. In this study we examined the role of nitric oxide (NO) in the ischemia-induced release of DA. A microdialysis probe was stereotactically placed into the corpus striatum of 16 Sprague-Dawley rats for DA, 3,4-dihydroxyphenylacetic acid (DOPAC), and homovanillic acid (HVA) level determinations. After probe stabilization, the animals received either NG-nitro-L-arginine-methyl ester (L-NAME), a NO synthase inhibitor, or vehicle through the microdialysis probe. Temporary global forebrain ischemia was induced using bilateral carotid artery ligature tightening and controlled hemorrhagic hypotension for 15 min. L-NAME administration caused a reduction in ischemic estimated extraneuronal DA concentration by 60% (P < 0.005) compared with control. There was an increase in both DOPAC and HVA concentrations during the recovery period compared to baseline values in the control group (P < 0.05). L-NAME also caused a reduction in HVA concentration compared to vehicle administration during the latter part of recovery (P < 0.05). These data support the concept that ischemic dopamine release may be mediated by NO. This NO-modulated DA release may contribute to the previously reported deleterious neurotoxic effects of NO during ischemia.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1995

Transesophageal echocardiography can be used to screen for ascending aortic atherosclerosis.

Atherosclerosis of the ascending aorta may be associated with a higher perioperative stroke risk in cardiac surgery. This study investigated the use of biplane transesophageal echocardiography (TEE) scanning of the entire thoracic aorta to predict the presence of plaque in the ascending aorta. Eighty-one patients (57 male, 24 female; aged 32-88 yr, mean age 64 yr) scheduled for elective cardiac surgery participated in an institutional review board-approved protocol. A comprehensive examination of the entire thoracic aorta in both the longitudinal and transverse planes was performed. After pericardiotomy, a sterilely draped 7-MHz probe was used to scan the entire ascending aorta in both long and short axis views. In both echocardiographic examinations, the presence and location of protruding plaques and intimal thickening > 3 mm were recorded. Using epiaortic (EPI) scanning as the "gold standard," the sensitivity, specificity, positive predictive value, and negative predictive value of TEE for detecting ascending aortic atherosclerosis were calculated. Fourteen (17%) of the 81 patients had significant atherosclerotic disease of the ascending aorta as diagnosed by EPI echocardiography. The sensitivity of TEE was 100%, the specificity was 60%, the positive predictive value was 34%, and the negative predictive value was 100%. These data show that, if the complete biplane TEE examination is negative for plaque, it is highly unlikely that there is significant plaque in the ascending aorta. If the TEE examination is positive for plaque, there is a 34% chance that there is significant disease of the ascending aorta, and EPI scanning should be considered. Thus, TEE is a very sensitive but only mildly specific method of determining whether ascending aortic atherosclerosis is present.

Adult↗
PubMed1995

Autologous platelet-rich plasmapheresis: risk versus benefit in repeat cardiac operations.

Preoperative platelet-rich plasmapheresis has been suggested as a means of reducing homologous blood transfusions in cardiac surgical patients. The current study evaluated this technique in patients undergoing repeat cardiac operations. Fifty-two patients undergoing repeat myocardial revascularization and/or valve replacement were evaluated in a prospective randomized controlled study design. Autologous platelet-rich plasma (PRP) was harvested after the induction of anesthesia in the experimental group. After reversal of heparin, each patient received his or her autologous plasma. Patients in the control group did not have plasmapheresis and received standard transfusion therapy if coagulation variables were abnormal and a coagulopathy was clinically evident. Routine coagulation tests, thromboelastography (TEG), perioperative bleeding, and transfusion requirements were compared in the two groups. Forty-four patients completed the study. A significantly larger volume of packed red blood cells (PRBCs) was transfused in the PRP group than in the control group (P = 0.03). Platelet and fresh frozen plasma (FFP) transfusions did not differ between the two groups. Mediastinal tube drainage did not differ between the two groups. During PRP infusion, 60% of the patients required treatment for moderate hypotension (mean arterial pressure [MAP] < 60 mm Hg). Only 16% of control patients required treatment for hypotension during the comparable time period (P < 0.05). No patient who completed the study returned to the operating room for postoperative bleeding. These data suggest that PRP did not reduce postbypass bleeding or transfusion requirements in repeat cardiac surgical patients. Moreover, the incidence of hypotension during PRP reinfusion introduces a potential risk to the procedure in the absence of any obvious benefit.

Blood Coagulation Tests↗
PubMed1995

A two-center comparison of the cardiovascular effects of cisatracurium (Nimbex) and vecuronium in patients with coronary artery disease.

Cisatracurium (Nimbex) is an intermediate-acting benzylisoquinolinium neuromuscular blocker that is one of the stereoisomers of atracurium. It causes no clinically significant cardiovascular side effects or histamine release in doses up to 8 x ED95 in healthy patients. Seventy patients undergoing elective myocardial revascularization consented to participate in an Institutional Review Board approved pilot study (10 patients) and an open-label, randomized, controlled trial comparing the hemodynamic effects of cisatracurium with vecuronium (60 patients) at two centers. The patients were anesthetized using 100% oxygen, fentanyl, and midazolam, and tracheal intubation was facilitated with succinylcholine. At least 5 min after tracheal intubation, baseline hemodynamic measurements were obtained. The patients received 0.10 mg/kg of cisatracurium (2 x ED95) or 0.10 mg/kg of vercuronium (2 x ED90) as follows: cisatracurium over 60 s (Pilot Group A, n = 5); cisatracurium over 30 s (Pilot Group B, n = 5); cisatracurium over 5-10 s (Group C, n = 30); or vecuronium over 5-10 s (Group D, n = 30). The hemodynamic measurements were repeated at 2, 5, and 10 min after cisatracurium or vecuronium injection. There were no episodes of cutaneous flushing. One patient was hypotensive before and after cisatracurium administration, and was excluded from analysis. Otherwise, there were no episodes of hypotension requiring therapy in any patient after cisatracurium. Fifteen patients overall were excluded from the analysis for one or more of the following: light anesthesia, treatment for hypotension < 10 min prior to baseline, or equipment difficulties.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Estimation of pharmacokinetic model parameters.

This paper addresses the problem of estimating the depth of anesthesia in clinical practice where many drugs are used in combination. The aim of the project is to use pharmacokinetically-derived data to predict episodes of light anesthesia. The weighted linear combination of anesthetic drug concentrations was computed using a stochastic pharmacokinetic model. The clinical definition of light anesthesia was based on the hemodynamic consequences of autonomic nervous system responses to surgical stimuli. A rule-based expert system was used to review anesthesia records to determine instances of light anesthesia using hemodynamic criteria. It was assumed that light anesthesia was a direct consequence of the weighted linear combination of drug concentrations in the patient's body that decreased below a certain threshold. We augmented traditional two-compartment models with a stochastic component of anesthetics' concentrations to compensate for interpatient pharmacokinetic and pharmacodynamic variability. A cohort of 532 clinical anesthesia cases was examined and parameters of two compartment pharmacokinetic models for 6 intravenously administered anesthetic drugs (fentanyl, thiopenthal, morphine, propofol, midazolam, ketamine) were estimated, as well as the parameters for 2 inhalational anesthetics (N2O and isoflurane). These parameters were then prospectively applied to 22 cases that were not used for parameter estimation, and the predictive ability of the pharmacokinetic model was determined. The goal of the study is the development of a pharmacokinetic model that will be useful in predicting light anesthesia in the clinically relevant circumstance where many drugs are used concurrently.

Anesthetics, Inhalation↗