Bilateral brachial paralysis from watershed infarction after coronary artery bypass. A report of two cases and review of the predisposing anatomic and physiological mechanisms.

Bilateral brachial paralysis and bilateral visual field defects developed after coronary artery bypass in two patients. These deficits, caused by cerebral watershed infarctions, probably resulted from global cerebral hypoperfusion during cardiopulmonary bypass, although bypass had been maintained with high perfusion flows (2.0 to 3.0 L/min/m2) and perfusion pressures from 50 to 90 mm Hg. No systemic hypoperfusion or hypotension occurred before or after cardiopulmonary bypass. Cerebral watershed infarctions occur predominantly in the boundary zones between the anterior, middle, and posterior cerebral arteries. In previous reports, watershed infarctions most often occurred as preterminal events in patients after sustained episodes of obvious hypoperfusion. The occurrence of such major neurological deficits in two patients without systemic hypoperfusion suggests that traditionally accepted flows and perfusion pressures do not assure adequate cerebral blood flow during cardiopulmonary bypass.

Regional cerebrovascular reactivity to carbon dioxide during cardiopulmonary bypass in patients with cerebrovascular disease.

In patients with cerebrovascular disease, hypercarbia may cause redistribution of regional cerebral blood flow from marginally perfused to well-perfused regions (intracerebral steal), as evidenced by regional cerebral blood flow studies during carotid endarterectomy. During hypothermic cardiopulmonary bypass, the pH-stat method of acid-base management produces relative hypercarbia. To determine whether pH-stat management produces relative hypercarbia. To determine whether pH-stat management induces intracerebral steals, we investigated nine patients with cerebrovascular disease undergoing coronary artery bypass grafting. During hypothermic cardiopulmonary bypass, arterial carbon dioxide tension was varied in random order between 40 mm Hg and 60 mm Hg (uncorrected for body temperature). Regional cerebral blood flow was measured by clearance of 133 xenon injected into the arterial inflow cannula. Nasopharyngeal temperature (26.8 degrees-28.0 degrees +/- 2.2 degrees-3.0 degrees C), perfusion flow rate (2.14-2.18 +/- 0.70-0.73 L/min/m2), mean arterial pressure (67-68 +/- 6-9 mm Hg), arterial carbon dioxide tension (302-308 +/- 109-113 mm Hg), and hematocrit (23% +/- 4%) were maintained within narrow limits in each patient during arterial carbon dioxide tension manipulation. Global mean cerebral blood flow values were similar to previously reported values in patients free of cerebrovascular disease; patients in this study averaged 15.2 +/- 2.5 ml/100 gm/min at an arterial carbon dioxide tension of 46.1 +/- 8.4 mm Hg and 25.3 +/- 6.1 ml/100 gm/min at an arterial carbon dioxide tension of 71.1 +/- 11.8 mm Hg. Carbon dioxide reactivity, defined as mean global cerebral blood flow (in ml/100 gm/min) divided by arterial carbon dioxide tension (in mm Hg), was similar in the region having the lowest regional cerebral blood flow and in the brain as a whole. No patient developed evidence of an intracerebral steal at the higher arterial carbon dioxide tension. During hypothermic cardiopulmonary bypass, higher levels of arterial carbon dioxide tension, such as those associated with the pH-stat management technique, are apparently not associated with potentially harmful redistribution of cerebral blood flow in patients with cerebrovascular disease.

Coronary revascularization in patients with bilateral internal carotid occlusions.

Coronary revascularization that is neurologically uneventful in patients with bilateral totally occluded internal carotid arteries has not been previously reported. We performed saphenous vein coronary artery bypass grafting on three such patients and observed them for 6 to 23 months. Preoperatively two of our patients had chronic stable symptoms of cerebrovascular insufficiency, and one had received cerebral revascularization via a superficial temporal-to-middle cerebral artery bypass. Controversy exists regarding proper cerebral protective maneuvers during coronary revascularization for patients with advanced cerebrovascular disease. Cerebral protection for our patients during cardiopulmonary bypass included hypothermia and high perfusion flows and pressures. Two patients also received prophylactic sodium thiopental. None of these three patients had a stroke perioperatively or during the follow-up period. We believe that these case histories strongly suggest that the functional state of the cerebral collateral circulation, as judged by preoperative neurological symptoms, predicts neurological outcome after coronary revascularization better than the specific occlusive anatomy of the extracranial carotid arteries.

Cerebrovascular and cerebral metabolic effects of alterations in perfusion flow rate during hypothermic cardiopulmonary bypass in man.

Recent experimental and clinical investigations provide conflicting evidence regarding the effects of changes in the systemic flow rate from the pump oxygenator on cerebral blood flow and the cerebral metabolic rate of oxygen consumption. However, the results of existing clinical studies are difficult to interpret because of the confounding effects of differences in management of arterial carbon dioxide tension and use of anesthetic and vasoactive agents during cardiopulmonary bypass. To clarify the relationship among perfusion flow rate, cerebral blood flow, and cerebral metabolic rate of oxygen consumption in man during hypothermic cardiopulmonary bypass, we varied perfusion flow rate in random order to either 1.75 or 2.25 L.min-1.m-2 and studied cerebral blood flow (measured by clearance of xenon 133) and cerebral metabolic rate of oxygen consumption (estimated as the product of cerebral blood flow and the cerebral arteriovenous oxygen content difference) in patients managed with both the alpha-stat (group 1) and the pH-stat (group 2) methods of pH and arterial carbon dioxide tension adjustment. We measured the cerebral arteriovenous oxygen content difference using radial arterial and jugular venous bulb blood samples. In each patient other variables known to exert effects on cerebral blood flow and cerebral metabolic rate of oxygen consumption, including temperature, arterial carbon dioxide tension, arterial oxygen tension, mean arterial pressure, and hematocrit, were maintained constant between measurements. In both groups, mean arterial pressure at both pump flow rates was similar because of spontaneous reciprocal alterations in systemic vascular resistance, that is, as perfusion flow rate declined, systemic vascular resistance increased; as perfusion flow rate increased, systemic vascular resistance declined. Under these tightly controlled conditions, pump flow variation per se exerted no effect on cerebral blood flow or cerebral metabolic rate of oxygen consumption in either group.

Heparin dosing and monitoring for cardiopulmonary bypass. A comparison of techniques with measurement of subclinical plasma coagulation.

Subclinical plasma coagulation during cardiopulmonary bypass has been associated with marked platelet and clotting factor consumption in monkeys. To better define subclinical coagulation in man, we measured plasma fibrinopeptide A concentrations before, during, and after cardiopulmonary bypass. Patients were assigned to one of three groups of heparin management: group 1 (n = 10)--initial heparin dose 300 IU/kg, with supplemental heparin if the activated coagulation time fell below 400 seconds; group 2 (n = 6)--initial heparin dose 250 IU/kg, with supplemental heparin if activated coagulation time was less than 400 seconds; and group 3 (n = 5)--initial heparin dose 350 to 400 IU/kg, with supplemental heparin if whole blood heparin concentration was less than or equal to 4.1 IU/ml. Activated coagulation time and heparin concentration were measured every 30 minutes during cardiopulmonary bypass, and fibrinopeptide A was measured at hypothermia, normothermia, and whenever activated coagulation time was less than 400 seconds. Quantitative and qualitative blood clotting competence was assessed after cardiopulmonary bypass, including mediastinal drainage for the first 24 hours. Fibrinopeptide A values were markedly elevated during cardiopulmonary bypass but were well below the levels present before and after cardiopulmonary bypass. Fibrinopeptide A correlated inversely with heparin concentration during cardiopulmonary bypass (r = -0.46, p = 0.03), but higher fibrinopeptide A levels during cardiopulmonary bypass did not correlate with post-cardiopulmonary bypass coagulopathy. Group 3 patients received the highest heparin doses (p less than 0.05) and had the greatest postoperative blood loss (p less than 0.05). Protamine dose and heparin concentration during cardiopulmonary bypass correlated best with postoperative mediastinal drainage. Our findings support the following conclusions: (1) compensated subclinical plasma coagulation activity occurs during cardiopulmonary bypass despite activated coagulation time greater than 400 seconds or heparin concentration greater than or equal to 4.1 IU/ml; (2) post-cardiopulmonary bypass mediastinal drainage correlates strongly with increased heparin concentration during cardiopulmonary bypass (p less than 0.05) and protamine dose (p less than 0.05); and (3) during cardiopulmonary bypass at both normothermia and hypothermia, activated coagulation times greater than 350 seconds result in acceptable fibrinopeptide A levels and post-cardiopulmonary bypass blood clotting.

Predictive value of blood clotting tests in cardiac surgical patients.

This study prospectively evaluated numerous tests of clotting function in 897 consecutive adult cardiac surgical patients over 18 months. This included coronary operation, valve replacement, and reoperative patients. The tests included activated clotting time, activated partial thromboplastin time, prothrombin time, thrombin time, fibrinogen, fibrin/fibrinogen degradation products, platelet count, and Duke's earlobe bleeding time. Other variables such as age, sex, and cardiopulmonary bypass duration were included in the multivariate analysis. Statistically significant correlations were found between 16-hour mediastinal drainage and activated partial thromboplastin time, fibrinogen, activated clotting time, fibrin/fibrinogen degradation products, platelet count, and prothrombin time. Scatter plots indicate that these relationships, although statistically significant, had little predictive value and were largely significant as a result of the large number of patients in each group, which permitted weak correlations to reach statistical significance. The best multivariate model constructed could explain only 12% of the observed variation in postoperative blood loss. Because the predictive values of the tests are so low, it does not appear sensible to screen patients routinely using these clotting tests shortly after cardiopulmonary bypass.

The perils of esophageal prosthesis placement in malignant tracheoesophageal fistula.

Endoesophageal prostheses are sometimes used in palliative therapy of esophageal carcinoma. Placement or subsequent manipulation of these devices may require general anesthesia, and these anesthetics are fraught with potential complications, both from the patient's illness and from the prosthesis itself. The two patients in our report presented anesthetic challenges, including acute upper airway obstruction occurring outside the operating theater and management of malignant tracheoesophageal fistula.

Effectiveness of intraoperative autologous whole blood and platelet-rich plasma in cardiac surgery.

Autologous whole blood and platelet-rich plasma harvested intraoperatively before cardiopulmonary bypass have been used by many in an effort to reduce the use of allogeneic blood transfusions during cardiac surgery. This brief review analyses the literature published concerning those two techniques. Although theoretically appealing, neither technique appears at present to withstand close scrutiny because of limitations in the design of many clinical studies. Efforts at blood transfusion avoidance during cardiac surgery may be best directed toward the salvage of intraoperative blood (including the residual oxygenator circuit contents), selective acceptance of low haemoglobin concentrations, and prophylactic administration of antifibrinolytic drugs.

Update on cardiopulmonary bypass.

Investigations into cardiopulmonary bypass continue to refine knowledge and clinical practice. Recent investigations have emphasized neurological complications, introducing the possibility of genetic predisposition as a risk factor. Appropriate flows, pressures, and hematocrit levels during cardiopulmonary bypass continue to create controversy. Whereas previous debate has centered around appropriate temperature management, recent discussions consider the possibility that mild hypothermia after cardiopulmonary bypass might be neuroprotective. Meta-analyses and prospective investigations continue to suggest the virtual equivalence of aprotinin and lysine analogues in reducing bleeding and transfusion after cardiopulmonary bypass. Several recent studies identified the mechanisms and severity of the inflammatory response to cardiopulmonary bypass, as well as possible techniques for attenuating inflammation.

Heparin-coated cardiopulmonary bypass circuits.

The indications for heparin-coated extracorporeal circuits cannot be defined or limited at present. Clinical investigation remains at an early stage of development. In situations where the risk of systemic anticoagulation is high, this technology would seem to hold great promise. Examples include extracorporeal lung assist and resuscitation from accidental hypothermia. Some have also suggested the use of heparin-coated circuits for percutaneous bypass in cardiopulmonary resuscitation. A significant advantage might also accrue in noncardiac surgical procedures requiring cardiopulmonary bypass, such as complex cerebral aneurysm or arteriovenous malformation resections, resections of the tracheal carina, or bilateral lung transplantations. Its role in routine cardiac surgical procedures remains uncertain, but the work of von Segesser et al suggests a need for continued investigation in that setting using reduced levels of systemic anticoagulation. That endeavor will be greatly assisted by the recent development of heparin-coated cardiotomy reservoirs. Although heparin-coated circuits have been safely used for extracorporeal lung assist with little or no systemic anticoagulation, prospective studies are clearly needed to determine if this approach is advantageous, and it would seem appropriate to develop heparin coating for silicone-based membrane oxygenators.

Accuracy of four indirect methods of blood pressure measurement, with hemodynamic correlations.

In 38 adults undergoing cardiac surgery, 4 indirect blood pressure techniques were compared with brachial arterial blood pressure at predetermined intervals before and after cardiopulmonary bypass. Indirect blood pressure measurement techniques included automated oscillometry, manual auscultation, visual onset of oscillation (flicker) and return-to-flow methods. Hemodynamic measurements or calculations included heart rate, cardiac index, stroke volume index, and systemic vascular resistance index. Indirect and intraarterial blood pressure values were compared by simple linear regression by patient and measurement period. Measurement errors (arterial minus indirect blood pressure) were calculated, and stepwise regression assessed the relationship between measurement error and heart rate, cardiac index, stroke volume index, and systemic vascular resistance index. Indirect to intraarterial blood pressure correlation coefficients varied over time, with the strongest correlations often occurring at the first and last measurement periods (preinduction and 60 minutes after cardiopulmonary bypass), particularly for systolic blood pressure. Within-patient correlations between indirect and arterial blood pressure varied widely--they were consistently high or low in some patients. In other patients, correlations were especially weak with a particular indirect blood pressure method for systolic, mean, or diastolic blood pressure; in some cases indirect blood pressure was inadequate for clinical diagnosis of acute blood pressure changes or trends. The mean correlations between indirect and direct blood pressure values were, for systolic blood pressure: 0.69 for oscillometry, 0.77 for auscultation, 0.73 for flicker, and 0.74 for return-to-flow; for mean blood pressure: 0.70 for oscillometry and 0.73 for auscultation; and for diastolic blood pressure: 0.73 for oscillometry and 0.69 for auscultation. The mean measurement errors (arterial minus indirect values) for the individual indirect blood pressure methods were, for systolic: 0 mm Hg for oscillometry, 9 mm Hg for auscultation, -5 mm Hg for flicker, 7 mm Hg for return-to-flow; for mean: -6 mm Hg for oscillometry, and -3 mm Hg for auscultation; and for diastolic: -9 mm Hg for oscillometry and -8 mm Hg for auscultation. Mean measurement error for systolic blood pressure was thus least with automated oscillometry and greatest with manual auscultation, while standard deviations ranging from 9 to 15 mm Hg confirmed the highly variable nature of single indirect blood pressure measurements. Except for oscillometric diastolic blood pressure, a combination of systemic hemodynamics (heart rate, stroke volume index, systemic vascular resistance index, and cardiac index) correlated with each indirect blood pressure measurement error, which suggests that particular numeric ranges of these variables minimize measurement error.(ABSTRACT TRUNCATED AT 400 WORDS)

Adverse reactions to protamine sulfate during cardiac surgery in diabetic and non-diabetic patients.

The incidence of adverse reactions to protamine sulfate range from 0.06% to 27% and vary from mild urticaria to anaphylactic shock and death. In a retrospective analysis of 2996 patients, only four subjects experienced an adverse reaction due to protamine. Two individuals were NPH-insulin-dependent diabetics and two patients had exposure to protamine only during cardiac catheterization. Skin test titrations to protamine were done in three of four patients. One patient had a positive reaction at a 100-micrograms/mL dilution whereas the other two patients had positive reactions at 1000 micrograms/mL. In a comparable number of normal subjects, the threshold for a positive immediate skin response was 1000 micrograms/mL. Since the observed incidence of adverse reactions was 2.9% in NPH-insulin-dependent diabetics and 0.07% in non-diabetics, this represents a nearly 40-fold increased risk for diabetic patients (P less than .005). Skin testing appears to have limited applicability in the assessment of protamine sensitivity.

Heparin content of washed red blood cells from the cardiopulmonary bypass circuit.

Reinfusion of red blood cells (RBC) from the extracorporeal circuit following cardiopulmonary bypass (CPB) reduces patient exposure to homologous blood. Because infusing unneutralized heparin might exacerbate postoperative bleeding, this study examines the heparin content of the washed packed RBC produced by a commonly used autotransfusion device. This RBC product was derived from the residual whole blood in the oxygenator circuit after CPB. A wash volume of 750 mL of normal saline produced heparin concentrations below 0.04 USP U/mL. A 500 mL wash volume yielded heparin concentrations ranging from 0.08 to 0.22 USP U/mL, and could be used if time did not permit an additional wash. RBCs produced by the usual complete wash cycle do not contain clinically significant amounts of heparin; thus, they would not require a supplemental protamine dose.

A comparison of brachial, femoral, and aortic intra-arterial pressures before and after cardiopulmonary bypass.

Following recent evidence that brachial and femoral artery pressures are more reliable than radial artery pressures after cardiopulmonary bypass, thirty-one adults had simultaneous pre- and post-bypass measurements of brachial, femoral, and ascending aortic pressures. Two minutes after cardiopulmonary bypass, brachial artery systolic pressure and mean arterial pressure fell significantly below corresponding pressures in the femoral artery and aorta. Five minutes after cardiopulmonary bypass, only brachial artery systolic pressure was still less than femoral and aortic systolic pressures. By ten minutes after bypass, all significant pressure differences had resolved except between brachial and femoral artery systolic pressures. Clinically significant (greater than or equal to 5 mmHg) aortic-to-brachial reductions in mean arterial pressures occurred in six (19%) patients at two minutes and in three (10%) patients at five and ten minutes after bypass. Equivalent aortic-to-femoral mean pressure diminution occurred in two (6%) patients at two minutes and one (3%) patient at five and ten minutes after bypass. Neither systemic vascular resistance nor body temperatures contributed significantly to post-bypass central-to-peripheral pressure reductions. Immediately following bypass, femoral artery pressures reproduce central aortic pressures more reliably than do radial or brachial artery pressures.

The clinical onset of heparin is rapid.

This study used the activated clotting time (ACT) to determine the clinical onset of four different doses of heparin after bolus injection into the central circulation. Ten consenting adults (Group A) undergoing coronary artery bypass grafting were given 350 U/kg of bovine lung heparin and had simultaneous duplicate arterial and venous ACT determinations at baseline and at 30, 60, 90, 120, 180, and 600 s after heparin injection. Twenty additional coronary artery bypass grafting patients were alternately assigned to one of two 10-patient groups (B and C), which were given 200 and 300 U/kg of bovine lung heparin, respectively. Group D consisted of 10 abdominal aortic aneurysmectomy patients who received 70 U/kg of bovine lung heparin. In Groups B, C, and D, duplicate ACT measurements were taken from an indwelling arterial catheter at baseline and at 30, 60, 90, 120, 180, and 300 s after completion of a bolus injection of heparin into the central circulation. After a 70 U/kg heparin dose, all patients had significant ACT prolongation within 30 s, and 8 of 10 had effectively achieved their peak anticoagulation response by that time. In all patients receiving 200, 300, and 350 U/kg of heparin, arterial anticoagulation (ACT > 300 s) occurred and in most patients peaked within 30 s after heparin administration (P < 0.05). Arterial and venous ACTs did not differ significantly from each other at any measurement period, but venous ACTs peaked slightly later than arterial ACTs (within 60 s in 9 of 10 patients). When 200 U/kg or more of heparin is administered into the central venous circulation in hemodynamically stable anesthetized patients, peak arterial ACT prolongation occurs within 30 s and peak venous ACT prolongation within 60 s.

Minimally invasive direct coronary artery bypass: anesthetic, monitoring, and pain control considerations.

OBJECTIVE: Minimally invasive direct coronary artery bypass (MIDCAB) provides many anesthetic challenges including monitoring, managing myocardial ischemia, and pain control. The objective was to evaluate the monitoring requirements and the potential benefits of preischemic conditioning and intrathecal morphine sulfate in MIDCAB patients. DESIGN AND SETTING: This review was retrospective and unrandomized and was conducted at Allegheny University Hospitals, Allegheny General, Pittsburgh, PA. PARTICIPANTS: Sixty-four patients with single coronary artery lesions (> 70% obstruction) underwent attempted MIDCAB during a 1-year period between November 1995 and November 1996. Seven patients required conversion to conventional coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) and two patients required extended thoracotomy incisions. This report describes the remaining 55 patients who underwent MIDCAB. INTERVENTIONS: Some of the MIDCAB patients received intrathecal morphine before anesthetic induction. Ischemic preconditioning was assessed in a subset of patients. RESULTS: MIDCAB was performed in 55 of 64 patients. Transesophageal echocardiography (TEE) was used in all patients and a pulmonary artery catheter was used in 43% of patients. Esmolol was used in 25% of patients to reduce motion of the left ventricle (LV) during the left internal mammary artery (LIMA)-LAD anastomosis, but was used less often as the surgeons adapted to the use of a retractor that stabilized the ventricular wall adjacent to the site of the LIMA-LAD anastomosis. LAD occlusion caused reversible, regional systolic dysfunction by TEE in the anterior and apical LV segments. During LAD occlusion, nitroglycerin was used in 61% of patients and phenylephrine in 24%. Ischemic preconditioning did not prevent increases in systemic or pulmonary artery pressures during LAD occlusion. Most (85%) patients were extubated in the operating room. Intrathecal morphine decreased postoperative analgesic requirements. The mean hospital length of stay (LOS) was 4.0 +/- 1.7 days (range, 1 to 10 days). CONCLUSIONS: MIDCAB may reduce hospital LOS for patients with single vessel coronary artery lesions when compared with median sternotomy with a LIMA-LAD graft performed on cardiopulmonary bypass. Pharmacologic heart rate control during the LIMA-LAD anastomosis is not critical with the use of a surgical retractor which diminishes ventricular motion. A single 5-minute test LAD occlusion did not protect against subsequent regional ischemic dysfunction in our subset of patients with normal baseline function.

Baseline activated coagulation time should be measured after surgical incision.

The activated coagulation time (ACT) is widely used to guide heparin and protamine dosing during cardiac surgery. A common protocol involves establishing a baseline ACT before administering heparin, then using this ACT as a target value for assessing the adequacy of heparin neutralization after cardiopulmonary bypass. Results vary in previous comparisons of baseline ACT to postprotamine ACT, with some showing postprotamine ACT significantly below baseline values. The present study examined ACTs at three possible baseline intervals in 68 patients at two institutions: (a) before anesthetic induction; (b) after anesthetic induction; and (c) after sternotomy. Baseline ACT decreased significantly with anesthesia and surgery. The poststernotomy baseline ACT best matched the postprotamine ACT. It appears likely that surgery induces a thromboplastic response that decreases ACT. Establishing baseline ACT before anesthetic induction would predispose to false diagnoses of adequate protamine neutralization after cardiopulmonary bypass, because ACT is relatively insensitive to low concentrations of unneutralized heparin. Baseline ACTs should therefore be measured after surgical incision.

Rapid administration of a narcotic and neuromuscular blocker: a hemodynamic comparison of fentanyl, sufentanil, pancuronium, and vecuronium.

High-dose narcotic anesthetic inductions usually avoid circulatory depression better than do other techniques; however, the selection of a narcotic and neuromuscular blocker influences subsequent hemodynamic responses. One hundred-one patients having aortocoronary bypass graft (CABG) surgery were investigated using four combinations of a narcotic and neuromuscular blocker: group FP (fentanyl 50 micrograms/kg, pancuronium 100 micrograms/kg); group FV (fentanyl 50 micrograms/kg, vecuronium 80 micrograms/kg); group SP (sufentanil 10 micrograms/kg, pancuronium 100 micrograms/kg); and group SV (sufentanil 10 micrograms/kg, vecuronium 80 micrograms/kg), each combination being administered over 2 minutes. Hemodynamic functions were then monitored for 10 minutes before tracheal intubation. Significant changes included increases in heart rate in the groups receiving pancuronium and decreases in those receiving vecuronium. In all groups mean arterial pressure initially decreased; systemic vascular resistance index decreased significantly in all groups except SV. Cardiac index decreased significantly only in group SV. Circulatory depression requiring treatment with vasopressor or anticholinergic drugs was more common in patients given vecuronium. Cardiac arrhythmia occurred most often in group SP; only in group FP were there no arrhythmias, ischemic changes, or hemodynamic disturbances requiring intervention. Time to onset of neuromuscular blockade did not differ among the four groups, but transient chest wall rigidity occurred significantly more often with sufentanil than with fentanyl. Overall, the fentanyl/pancuronium combination afforded the greatest hemodynamic stability, whereas the sufentanil/vecuronium combination proved least satisfactory because of bradycardia and hypotension, requiring treatment in 35% of group SV patients.(ABSTRACT TRUNCATED AT 250 WORDS)

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)

A comparison of radial, brachial, and aortic pressures after cardiopulmonary bypass.

Previous investigations have identified falsely low radial artery pressures after cardiopulmonary bypass (CPB). The present study investigates the relationship among radial, brachial, and aortic arterial pressures in 33 cardiac surgical patients following CPB. Two minutes after separation from CPB, clinically important (greater than or equal to 10 mmHg) underestimation of systolic aortic pressures occurred in 17 of 33 (52%) radial artery catheters, while occurring in seven of 33 (21%) brachial artery catheters. Radial artery mean pressure underestimated aortic mean pressure by greater than or equal to 5 mmHg in 21 of 33 (61%) patients two minutes after CPB, while an equivalent aortic-to-brachial artery mean arterial pressure difference occurred in nine of 33 (27%) patients. The incidence of aortic-to-radial mean arterial pressure differences greater than or equal to 5 mmHg decreased to 40% (four of ten patients) by ten minutes after CPB, although interpretation is complicated by decreased availability of aortic pressure measurements. Multivariate analysis failed to identify factors predisposed to central-to-peripheral pressure gradients. Radial and brachial arterial pressures were compared both before and after CPB in all 33 patients. Brachial artery systolic and mean pressures were higher than corresponding radial artery measurements two minutes after CPB (P less than 0.05), followed by gradual resumption of a normal brachial-to-radial pressure relationship over 60 minutes. Either vasospasm in the brachial and radial arteries or profound arteriolar vasodilation in the upper extremity might cause the observed central-to-peripheral arterial pressure differences. The progressive central-to-peripheral decrease in mean arterial pressure favors the latter mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)