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P G Barash

Publications and source records attributed to P G Barash.

At least 19 recordsLinked to original sources
PubMed1992

Automated St-segment trending: what does it mean?

This article is the first segment of what we hope will become a regular feature in the Journal of Clinical Monitoring. The Monitoring Dilemmas series is designed for clinicians who are struggling with the information presented by new monitoring. The past decade has seen an explosion in the number and type of clinical monitors in daily use. Health-care providers are increasingly faced with a plethora of monitoring data, often without guidance on how to interpret it. Each Monitoring Dilemma consists of a case report that describes a clinical dilemma brought on by information from a monitor--a dilemma that would not even have been considered had the monitor not been in place or existence. The case reports are sent to experts in the particular fields concerned. To prevent "Monday morning quarterbacking," each reviewer is sent several envelopes, each containing information that progressively reveals more and more about the case. The case is presented as it actually evolved, and the experts comment as the case unfolds. Thus, the reader can share the dilemma with the reviewers, as well as with the original clinicians. We welcome your comments on this new section. We also welcome your own Monitoring Dilemmas. Please contact the Section Editor, Dr Partridge, for more details.

Aged↗
PubMed1992

Complications occurring in the postanesthesia care unit: a survey.

To identify and quantitate complications occurring in the postanesthesia care unit (PACU), a prospective study evaluated 18,473 consecutive patients entering a PACU at a university teaching hospital. Using a standardized collection form, the incidence of intraoperative and PACU complications was determined. The combined PACU and intraoperative complication rate was 26.7%. Data showed a PACU complication rate of 23.7%, with an overall intraoperative complication rate of 5.1%. Nausea and vomiting (9.8%), the need for upper airway support (6.9%), and hypotension requiring treatment (2.7%) were the most frequently encountered PACU complications. Patients in whom PACU complications developed were analyzed by ASA physical status. Of all patients experiencing nausea and vomiting (n = 1571), the highest percentage were ASA physical status II patients (n = 831). Likewise, in the group of 1450 patients who demonstrated a need for upper airway support, 792 were ASA physical status II. In patients experiencing a major cardiovascular complication, for example, variables associated with a greater risk of developing any PACU complications were ASA physical status (status II), duration of anesthesia (2-4 h), anesthetic technique, emergency procedures, and certain types of surgical procedures (orthopedic or abdominal). For patients admitted with a temperature of less than 35 degrees C the duration of the PACU stay was 152 +/- 46 min compared with 116 +/- 65 min for patients with a temperature greater than or equal to 36 degrees C (P less than 0.01). In conclusion, events occurring during the PACU period continue to be a source of patient morbidity.

Adolescent↗
PubMed1992

Preoperative cardiac evaluation for noncardiac surgery: a functional approach.

The preoperative assessment of the high risk patient undergoing noncardiac surgery has traditionally been based on history, physical examination, and preoperative testing. We propose a method of assessing preoperative risk based on the presentation of coronary artery disease, exercise tolerance, and extent of the surgical procedure. Since this is an evolving field, as new information and perioperative management techniques become available, the preoperative evaluation of the high risk patient will change. We have presented one approach based on our interpretation of data from the current anesthesiology and cardiology literature. In the patient with a recent MI, the predischarge symptom-limited stress test and the electrocardiographic classification can be used to better stratify risk. In the patient with angina, testing should be reserved for those patients who are candidates for coronary revascularization or alternative surgical procedures. In the patient at risk of but without overt symptoms of coronary artery disease, the number of clinical risk factors can determine the probability of coronary artery disease in the individual patient. The decision to perform preoperative revascularization should be based on its anticipated improvement of both the short- and long-term prognosis of the patient considering the risk of such procedures. The objective assessment of LVEF should be performed in patients with a poor exercise tolerance with either a high risk of perioperative ischemia or a suspicion of cardiomyopathy.

Anesthesiology↗
PubMed1991

Preoperative evaluation of the cardiac patient for noncardiac surgery.

In summary, obtaining a comprehensive patient history is a critical part of the diagnostic and risk stratification process of the patient with cardiac disease undergoing non-cardiac surgery. Many of the factors associated with perioperative cardiac morbidity are treatable and early and aggressive management appears to have beneficial effects on morbidity and mortality rates.

Coronary Disease↗
PubMed1991

The predictive value of preoperative silent ischemia for postoperative ischemic cardiac events in vascular and nonvascular surgery patients.

Silent ischemia has been shown to be predictive of postoperative cardiac events in vascular surgery patients. However, no controlled data regarding its predictive value in nonvascular surgery patients are available. We studied 67 vascular surgery and 79 nonvascular surgery patients, all of whom had increased risk for cardiac disease, to determine whether the occurrence of preoperative silent myocardial ischemia is predictive of morbid postoperative cardiac events in a diverse surgical group. The presence of preoperative silent ischemia in both nonvascular and vascular surgical patients had similar predictive value (0.38 and 0.38, respectively) for postoperative morbid cardiac events. The absence of preoperative silent ischemia predicted an excellent outcome in patients undergoing nonvascular surgery (0.99), but was a less robust predictor in our vascular patients (0.86). These data suggest that the functional status of the coronary circulation is one of the most important determinants of outcome.

Aged↗
PubMed1991

Is the pressure rate quotient a predictor or indicator of myocardial ischemia as measured by ST-segment changes in patients undergoing coronary artery bypass surgery?

Perioperative myocardial ischemia is associated with an increased risk of perioperative myocardial infarction (PMI). Several attempts have been made to define intraoperative hemodynamic predictors of myocardial ischemia. In a canine preparation with coronary stenosis, a pressure rate quotient (PRQ = mean arterial pressure/heart rate) less than one (PRQ less than 1) indicated subendocardial myocardial ischemia. The authors tested this hypothesis in patients undergoing elective coronary artery bypass graft operation (CABG), using electrocardiogram (ECG) ST-segment changes (leads II/V5) to diagnose myocardial ischemia. Sixty (n = 60) patients having CABG surgery were prospectively studied before initiation of cardiopulmonary bypass. Calibrated ECG leads II and V5 (diagnostic mode) were monitored continuously and recorded with the use of a Hewlett-Packard computer ST-segment analyzer. In addition, arterial and pulmonary artery pressures were monitored. Ischemia was defined as new-onset ST deviation (greater than or equal to 1 mm from the baseline ECG). ECG and hemodynamic data were stored at 2-min intervals for subsequent computer analysis. Serial creatinine phosphokinase (CPK) X MB (%) determinations and 12-lead ECGs were collected for the initial 3 postoperative days. Of the 3,463 intervals (2 min) available for study, 3,322 (96%) were satisfactorily recorded for 60 patients. Ischemia occurred during 65 intervals in 9 patients (9 of 60), of which only 34% (22 of 65) were associated with a PRQ less than 1 (P less than 0.01). In contrast, there were 466 intervals during which PRQ was less than 1, but without ECG evidence of ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Onset of altered interventricular septal motion during cardiac surgery. Assessment by continuous intraoperative transesophageal echocardiography.

Abnormal motion of the interventricular septum is frequently observed after uncomplicated cardiac surgery. We sought to elucidate the mechanism underlying this phenomenon by using continuous echocardiographic imaging of the heart from a constant transesophageal location in 21 patients undergoing their first cardiac operation. Quantitative global and regional functional analyses were performed in each patient at baseline (stage 1), after median sternotomy (stage 2), after sternal retraction (stage 3), after pericardiotomy (stage 4), after completion of cardiopulmonary bypass (stage 5), and after chest closure (stage 6). During the first four surgical stages, mean left ventricular fractional shortening varied little among regions with a fixed reference system (maximum range, 31.6-39.2%; p = NS) but changed dramatically after the discontinuation of cardiopulmonary bypass (stage 5). The apparent medial hypokinesis that was observed (4.9 +/- 4.7% [SD]) was accompanied by lateral hyperkinesis (65.2 +/- 4.1%, p less than 0.0001). These regional differences were completely eliminated with a floating reference system (33.6 +/- 2.7% for medial, and 34.8 +/- 1.7% for lateral; p = NS), suggesting cardiac translation. Quantitative curvature analysis supported this conclusion, with preservation of baseline regional curvature seen throughout the procedure. The mean length of individual translational vectors (reflecting systolic movement of the endocardial centroid) remained minimal (less than or equal to 1.0 mm) through stage 4 but increased more than fourfold at stage 5, continuing in a medial direction after chest closure (5.2 +/- 3.0 mm and 271 +/- 6 degrees from anterior). Thus, abnormal postoperative septal motion is not caused by removal of restraining forces of the pericardium or anterior mediastinum but rather appears to be directly related to events occurring during cardiopulmonary bypass.

Cardiac Surgical Procedures↗
PubMed1990

Emergency tracheal intubation in the postanesthesia care unit: physician error or patient disease?

Inadequate airway maintenance has been a major factor in perioperative morbidity. To determine the incidence and etiology of emergency tracheal intubations in the postanesthesia care unit (PACU), we retrospectively reviewed 13,593 consecutive admissions to our PACU from October 1986 through October 1988. Twenty-six patients (26/13,593 = 0.19%) required the insertion of an endotracheal tube while in the PACU. Seventy-seven percent (20/26) of the intubations occurred within 1 h of extubation and/or admission to the PACU. Intubation was more common at the extremes of age; 54% of those intubated were more than 60 yr old (P = 0.003); 19% were less than 3 yr old (P less than 0.05). Twenty-three percent of the intubated patients had undergone otolaryngologic procedures (P = 0.008). Interestingly, 73% of the intubations occurred during the months of January through June (P = 0.016). Median PACU admission scores were lower for the intubated group (P less than 0.001). There was no association between intubation and gender (P = 0.74), anesthetic technique (P = 0.41), or anesthetic agent (P = 0.49). Of the 26 intubations, 18 (69%) were considered to be directly related to anesthetic management. Despite the extremely low incidence of emergency tracheal intubation in a heterogeneous group of patients admitted to our PACU, preventable anesthesia-related etiologic factors including excessive sedative or anesthetic effect, inappropriate fluid management, persistent muscle relaxant effect, and upper airway obstruction contributed to the majority of these intubations.

Adolescent↗
PubMed1989

Infusion of sodium nitroprusside induces platelet dysfunction in vitro.

The effect of sodium nitroprusside (SNP) infusion on platelet function was prospectively evaluated in 29 patients undergoing cardiac surgical procedures requiring cardiopulmonary bypass. Any patient receiving preoperative medication known to interfere with platelet function was excluded from this study. Platelet function was evaluated by measurement of platelet aggregation with both adenosine diphosphate (ADP) and epinephrine-induced aggregation tests. Ten patients served as a control population receiving fentanyl anesthesia and no SNP. Nineteen patients received SNP, as clinically indicated, following the induction of anesthesia (and prior to cardiopulmonary bypass) to maintain a mean blood pressure of 80 mmHg. The infusion rate and total dose of SNP delivered was recorded for each patient. Infusion rates of SNP greater than or equal to 3 micrograms.kg.-1 min-1 resulted in a dose-related decrease in platelet aggregation (P less than 0.05). This reduction in platelet function was accompanied by a concomitant increase in bleeding time from 5.8 +/- 0.6 to 9.3 +/- 0.4 min in the patients receiving SNP (P less than 0.05). In addition, with the administration of a total dose of SNP greater than or equal to 16 mg, a significant reduction in platelet aggregation (P less than 0.05) was observed. Platelet aggregation studies and bleeding time performed in the control group (following the administration of fentanyl (30 micrograms/kg) did not reveal any deviation from baseline values. The results from this in vivo study support previous in vitro data demonstrating a detrimental effect upon platelet function following SNP infusion.

Aged↗
PubMed1988

Effect of positive end-expiratory pressure on right ventricular performance. Importance of baseline right ventricular function.

Thirty-six patients with diverse baseline right ventricular function were evaluated during incremental positive end-expiratory pressure (PEEP) application. Right heart pressures, cardiac output, right ventricular ejection fractions, and ventricular volumes were obtained at each PEEP level. Right ventricular peak systolic pressure-end-systolic volume relations were analyzed as an index of contractile function. Patients with severely depressed baseline right ventricular ejection fractions (30 percent or less) had an increase in end-diastolic (270 +/- 74 to 391 +/- 76 ml, 0 to 20 cm water (H2O) PEEP, p less than 0.05) and end-systolic volumes (210 +/- 70 to 321 +/- 70 ml, 0 to 20 cm H2O PEEP, p less than 0.05). These patients also had a decline in estimated right ventricular contractile function at 20 cm H2O PEEP as estimated by the slope of systolic pressure-volume relations (0.12 to 0.04 mm Hg/ml, 0 to 15 and 15 to 20 cm H2O PEEP, respectively, p less than 0.05). Patients with normal (40 percent or more) or moderately depressed (31 to 40 percent) baseline right ventricular ejection fractions had no change in right ventricular volumes or estimated contractile function. Therefore, the effect of PEEP on right ventricular function differs depending on the baseline right ventricular ejection fraction.

Adult↗
PubMed1988

Control of perioperative hypertension during coronary artery surgery. A randomised double-blind study comparing isosorbide dinitrate and nitroglycerin.

A reduction in the causes of myocardial ischaemia remains of prime importance during coronary artery surgery. Hypertension with the ensuing increase in myocardial oxygen demand is a major factor in the aetiology of perioperative myocardial ischaemia. Nitroglycerin (NTG) has long been used beneficially to reduce myocardial oxygen demand by its effects on the systemic and peripheral vascular resistances. An alternative nitrate, isosorbide dinitrate (ISDN) is now available as an intravenous preparation, and may offer technical advantages, both due to its stability in solution and also its longer in vivo half-life. We designed and carried out a multi-centre study to compare and evaluate the efficacy of ISDN and NTG in the management of perioperative hypertension in 85 patients undergoing elective coronary artery surgery. A total of 288 events in which the systolic blood pressure (SBP) exceeded a predetermined trigger value were observed. ISDN was successful in treating hypertension in 63% of the events, whereas NTG had an 83% success. The SBP was significantly lowered after treatment with either ISDN, 155 mmHg to 138 mmHg, or NTG, 160 mmHg to 130 mmHg. The mean successful dose rate for ISDN was 6.5 micrograms kg-1 min-1, whereas for NTG this was 3.8 micrograms kg-1 min-1. In the ISDN group less events took place possibly due to the longer duration of this drug. In many previous studies NTG has been found to be effective in controlling hypertension; ISDN offers and alternative approach in reducing hypertension.

Coronary Artery Bypass↗
PubMed1988

The effect of incremental positive end-expiratory pressure on right ventricular hemodynamics and ejection fraction.

The effects of incremental positive end-expiratory pressure (PEEP) on right ventricular (RV) function were evaluated in 36 (n = 36) ventilated patients. Positive end-expiratory pressure was increased from 0 (baseline) to 20 cm H2O in 5-cm H2O increments and RV hemodynamics and thermally derived right ventricular ejection fraction (RVEF), right ventricular end-diastolic volume index (RVEDVI), and right ventricular end-systolic volume index (RVESVI) were computed. Right ventricular contractility was determined from the analysis of RV systolic pressure-volume relations. Right ventricular ejection fraction declined from 42 +/- 8% at baseline to 30 +/- 9% at 20 cm H2O PEEP. Right ventricular end-diastolic volume index declined between 0 and 5 cm H2O PEEP (103 +/- 42 to 92 +/- 34 ml.m-2) and then increased to 113 +/- 40 at 20 cm H2O PEEP. Right ventricular end-systolic volume index increased from 60 +/- 31 ml.m-2 at baseline to 79 +/- 34 ml.m-2 at 20 cm H2O PEEP. The slope (E) of the relation of RV peak systolic pressure to RV end-systolic volume index decreased from 0.26 mm Hg.m2.ml-1 between PEEP of 0-15 cm H2O to 0.05 mm Hg.m2.m-1 at PEEP greater than 15 cm H2O. It is concluded that low levels of PEEP have a predominant preload reducing effect on the RV. Above 15 cm H2O PEEP, RV volumes increase and E decreases, consistent with increased RV afterload and a decline in RV contractility.

Adult↗