The hemodynamic effects of anesthetic induction in vascular surgical patients chronically treated with angiotensin II receptor antagonists.

UNLABELLED: The use of angiotensin II receptor subtype-1 antagonists (ARA), recently introduced as antihypertensive drugs, is becoming more prevalent. We studied the prevalence and severity of hypotension after the induction of general anesthesia in 12 patients treated with ARA until the morning of surgery. The hemodynamic response to induction was compared with that of patients treated with beta-adrenergic blockers (BB) and/or calcium channel blockers (CB) (BB/CB group, n = 45) and angiotensin-converting enzyme inhibitors (ACEI) (ACEI group, n = 27). A standardized anesthesia induction protocol was followed for all patients. Hypotension occurred significantly (p < or = 0.05) more often in ARA-treated patients (12 of 12) compared with BB/CB-treated patients (27 of 45) or with ACEI-treated patients (18 of 27). There was a significantly (P < or = 0.001) increased ephedrine requirement in the ARA group (21+/-3 mg) compared with the BB/CB group (10+/-6 mg) or the ACEI group (7+/-4 mg). Hypotension refractory to repeated ephedrine or phenylephrine administration occurred significantly (P < or = 0.05) more in the ARA group (4 of 12) compared with the BB/CB group (0 of 45) or the ACEI group (1 of 27), but it was treated successfully by using a vasopressin system agonist. Treatment with angiotensin II antagonism until the day of surgery is associated with severe hypotension after the induction of anesthesia, which, in some cases, can only be treated with an agonist of the vasopressin system. IMPLICATIONS: Hypotensive episodes occur more frequently after anesthetic induction in patients receiving Angiotensin II receptor subtype-1 antagonists under anesthesia than with other hypotensive drugs. They are less responsive to the vasopressors ephedrine and phenylephrine. The use of a vasopressin system agonist was effective in restoring blood pressure when hypotension was refractory to conventional therapy.

Hemodynamic effects of epinephrine associated to an epidural clonidine-bupivacaïne mixture during combined lumbar epidural and general anesthesia.

Clonidine or epinephrine are frequently combined to epidural local anesthetics to strengthen sensory block and prolong analgesia. Both drugs impair the hemodynamic profile of central neural blockade but the effects of their combination on arterial pressure and heart rate are not known and were examined in this double-blind prospective randomised study. Forty four patients scheduled for lumbar disc surgery were allocated to two groups. Epidural anesthesia was obtained by administration of 150 micrograms clonidine in 15 ml bupivacaine 0.25% solution without (group C) or with (group C + E) 37.5 micrograms epinephrine. Systolic, mean, diastolic arterial pressure and heart rate were measured throughout the study. Combined epidural and general anesthesia induced a significant decrease in arterial pressure and heart rate in both groups. SAP and MAP decreased significantly less in the patients receiving epinephrine. Low dose epidural epinephrine decreases arterial pressure instability during combined epidural and general anesthesia.

Characterization of the specific response to serotonin of mouse tumour-feeding arterioles.

PURPOSE: To investigate the role of tumour versus non-tumour factors in the specific response to serotonin (5-HT) of tumour-feeding arterioles (TFA). MATERIALS AND METHODS: Using mouse models of intra-vital microscopy, the response to topical administration of 5-HT was studied in arterioles feeding tumours: fibrosarcoma (Meth A), murine mammary adenocarcinoma (EMT6) and human colo-rectal carcinoma (HRT18) intra-cutaneously implanted. RESULTS: For all types of tumour, 5-HT induced a far more pronounced constriction of TFA than of control arterioles. The presence of a tumour implanted in the connective tissue between the skin and the cremaster muscle also affected the reactivity of muscle arterioles. Conversely, the response to serotonin by neovessels grown after implantation of an exogenous element under the skin did not differ from that of control arterioles. CONCLUSIONS: Changes in reactivity to serotonin were not dependent on the type of tumour implanted in the skin and were not present for a non-tumour implant. The presence of the tumour can alter the reactivity of vessels from tissue in contact with the tumour even if these vessels did not feed the tumour. This phenomenon is local and was not found in the vessels at a distance from the tumour.

[Interviews with families of organ donors: analysis of motivation for acceptance or refusal of donation]. / Entretiens avec les familles de donneurs d'organes: analyse des motivations d'acceptation ou de refus du don.

OBJECTIVE: The reasons for organ donation acceptance or refusal are still unclear. This study analysed the influence of the circumstances of the conversations with the relatives of brain dead patients on their consent for organ donation. STUDY DESIGN: Prospective study. MATERIAL: The analysis included 41 questionnaires collected over nine months in one organ harvesting centre and focusing on the circumstances of death, the conditions of the conversations and the reasons for acceptance or refusal. METHODS: Questionnaire filled in by the physicians after the interviews of the relatives of brain dead patients. RESULTS: The refusal rate was higher (54 vs 21%) when only one physician participated in the conversation, when more than two relatives had to decide (42 vs 24%), when conversations took place during night or when the request for organ donation followed immediately the announcement of death (43 vs 20%). Most often the relatives gave their decision within minutes following the request. CONCLUSION: The circumstances of conversation with families play an essential role in their decision-making. A written guideline implementation for these conversations would probably be beneficial for the decisions of families in favour of organ donation.

Comparison between radionuclide ejection fraction and fractional area changes derived from transesophageal echocardiography using automated border detection.

BACKGROUND: Left ventricular fractional area changes (FAC) can be derived from transesophageal echocardiography using an automated border detection system. However, FAC has not yet been compared to left ventricular ejection fraction (EF) evaluated by a reference technique. The aim of this study was to correlate transesophageal echocardiography automated FAC to EF derived from radionuclide angiography to obtain a quantifying method of global left ventricular systolic function at the bedside. METHODS: Ten critically ill patients, whose lungs were mechanically ventilated, were included in this prospective study. Patients were scheduled for radionuclide EF evaluation when at least 75% of the endocardium was clearly visualized on transesophageal echocardiography. Patients with esophageal pathology or cardiac dysrhythmia were excluded. Ejection fraction derived from radionuclide angiography was measured using technetium 99m. Echocardiographic data were obtained using an ultrasound system with automated border capabilities. Simultaneous measurements of left ventricular EF and FAC were obtained for each patient, both before and after starting a dobutamine intravenous infusion to modify left ventricular contractility. RESULTS: Mean values for radionuclide EF and transesophageal echocardiography FAC were, respectively: 55% +/- 19% (range 19-89%) and 46% +/- 18% (range 17-80%). Left ventricular EF and FAC were significantly correlated (r = 0.85, SEE = 9.6%). Variations of EF and FAC, induced by dobutamine, were also correlated (r = 0.70, SEE = 4.9%). CONCLUSIONS: Fractional area changes determined by transesophageal echocardiography using automated border detection correlate well with radionuclide EF and may be used at the bedside to quantify left ventricular function in selected intensive care unit patients.

A study of the human aortic valve orifice by transesophageal echocardiography.

The transverse short-axis plane of the aortic valve was imaged by transesophageal echocardiography at a relatively high frame rate in 25 anesthetized patients undergoing heart surgery. The effective, time-averaged aortic valve area (a-AVA) was compared with areas obtained with triangular and circular valve orifice models (t-AVA and c-AVA, respectively). The aortic valve orifice was circular during 33.6% +/- 17.5% of systole. The relations between the triangular or circular aortic valve areas and a-AVA were as follows: t-AVA = 1.04 x a-AVA - 0.14 (r = 0.90; standard error of the estimate = 0.24 cm2) and c-AVA = 1.37 x a-AVA + 0.00 (r = 0.90; SEE = 0.30 cm2). Bias analysis showed no significant difference between a-AVA and t-AVA (bias = -0.04 +/- 0.23 cm2; difference not significant) but a significant overestimation of the average valve area by c-AVA (bias = +0.88 +/- 0.30 cm2; p < 0.001). Thus the aortic valve orifice was not circular for the entire duration of systole and valve area calculations based on a triangular model approximated a-AVA more closely than did those based on a circular model. These findings suggest that, for echocardiographic measurements that incorporate the aortic valve orifice area (e.g., stroke volume determinations), the use of a triangular valve area model, rather than a circular model, may produce more accurate results in anesthetized patients with heart disease.

Cardiac output by transesophageal echocardiography using continuous-wave Doppler across the aortic valve.

BACKGROUND: The use of transesophageal echocardiography for the determination of cardiac output (CO) has been limited to date. We assessed the capability of aortic continuous-wave Doppler transesophageal echocardiography to determine CO (DCO) in a transgastric long-axis imaging plane of the heart by comparing DCO to thermodilution CO (TCO). METHODS: DCO was determined in 63 consecutive patients undergoing cardiac surgery. Aortic valve area was obtained from the transverse short-axis view of the valve assuming a triangular shape for the valve orifice. Stroke volume was calculated as the product of velocity-time integral and aortic valve area: stroke volume = velocity-time integral x aortic valve area. DCO was calculated off-line, by multiplying stroke volume with heart rate: DCO = stroke volume x heart rate. RESULTS: The aortic valve orifice was easily imaged in all patients. Excellent-quality continuous-wave Doppler flow profiles were obtained in nearly all (62 of 63). A total of 109 DCO determinations were performed. Mean DCO was 4.35 +/- 1.18 l.min-1 (range 2.02-7.42 l.min-1), and mean TCO was 4.41 +/- 1.17 l.min-1 (range 2.24-8.94 l.min-1). Very high correlation and agreement were found between the two methods: DCO = 0.94 x TCO + 0.19, r = 0.94, SEE (standard error of the estimate) = 0.41 l.min-1; 95% confidence interval = 0.06 +/- 0.83 l.min-1. Relative changes from pre- to postbypass CO (delta) also showed a strong correlation (delta DCO = 0.93 x delta TCO + 5.4%, r = 0.82, SEE = 17.8%). For CO changes greater than 10%, Doppler was in accordance with thermodilution in 43 of 45 measurements. DCO repeatability coefficient was 0.51 l.min-1. CONCLUSIONS: Compared to thermodilution, continuous-wave Doppler measurements of blood flow velocity across the aortic valve in the transesophageal echocardiographic transgastric view allow accurate CO determination.