Factors influencing preoperative stress response in coronary artery bypass graft patients

BACKGROUND: In many studies investigating measures to attenuate the hemodynamic and humoral stress response during induction of anaesthesia, primary attention was paid to the period of endotracheal intubation since it has been shown that even short-lasting sympathetic cardiovascular stimulation may have detrimental effects on patients with coronary artery disease. The aim of this analysis was, however, to identify the influencing factors on high catecholamine levels before induction of anaesthesia. METHODS: Various potential risk factors that could impact the humoral stress response before induction of anaesthesia were recorded in 84 males undergoing coronary aortic bypass surgery, and were entered into a stepwise linear regression analysis. The plasma level of norepinephrine measured immediately after radial artery canulation was chosen as a surrogate marker for the humoral stress response, and it was used as the dependent variable in the regression model. Accordingly, the mean arterial blood pressure, heart rate and the calculated pressure-rate product were taken as parameters of the hemodynamic situation. RESULTS: Stepwise regression analysis revealed that the oral administration of low-dose clonidine (mean dose 1.75 μg·kg(-1)) on the morning of surgery was the only significant predictor (p = 0.004) of the high variation in preoperative norepinephrine plasma levels. This intervention decreased norepinephrine levels by more than 40% compared to no clonidine administration, from 1.26 to 0.75 nmol·l(-1). There was no evidence for dose-responsiveness of clonidine. All other potential predictors were removed from the model as insignificant (p > 0.05). The use of beta-blocker, ace-inhibitors, ejection fraction, and body mass index were significant determinants for the hemodynamic situation (heart rate, mean arterial pressure, pressure rate product) of the patient during the pre-induction period. CONCLUSION: The oral administration of clonidine is the only significant predictor for the observed variation of norepinephrine levels during the preoperative period. Lack of significant dose responsiveness suggests that even a low dose of the drug can attenuate the preoperative stress response and thus is recommended in cardiovascular high risk patients

Comparison of the effects of clonidine and hydroxyzine on haemodynamic and catecholamine reactions to microlaryngoscopy

BACKGROUND AND OBJECTIVE: This study compares the effect of oral clonidine vs. hydroxyzine on the haemodynamic and catecholamine responses to microlaryngoscopy. METHODS: Thirty-five ASA II-III patients were included in this double-blind randomized trial. The patients received either hydroxyzine 1 mg kg-1 (n = 18) or clonidine 3 micrograms kg-1 (n = 17) for their oral premedication 100 min before an intravenous induction of anaesthesia using propofol (2-3 mg kg-1) and fentanyl (2 micrograms kg-1). Arterial pressure and heart rate were measured before premedication, and throughout the procedure and recovery. Plasma catecholamine levels were determined before premedication, after induction, and 1.5, 30 and 120 min after laryngoscopy. RESULTS: Mean arterial pressure was significantly lower after clonidine, whereas there was no difference in heart rate and plasma catecholamine levels between the two groups. CONCLUSIONS: Clonidine for premedication significantly decreased mean arterial pressure during microlaryngoscopy and the following recovery phase but did not modify the overall haemodynamic response to the suspension microlaryngoscopic nociceptive stimulus

Comparaison de trois protocoles dans le controle de la reponse cardiovasculaire a laryngoscopie suspendue dans la chirurgie ORL. [Comparison of three protocols in the control of cardiovascular response to suspended laryngoscopy in ENT surgery]

The objective was to compare the effect of three pharmacological agents on the hemodynamic response to suspended laryngoscopy in micro ENT Surgery. Double blind randomised prospective study having included: groupe A (n = 16) having benefited before laryngoscopy of 150 mcg/kg esmolol, groupe B (n = 16) 15 mcg/kg of nicardipine, groupe C (n = 15) 1 mg/kg of lidocaine and groupe D (n = 16), placebo group. All groups were comparable for demographic and anesthetic data. A significant reduction of the heart rate and pressure rate product were noted in esmolol group during the endoscopic act and maintained until arousal. Whereas there was no difference in the blood pressure during the procedure whatever the pharmacological agent for prevention of cardiovascular complications for patients to risk in micro ENT surgery

Place de l'hémodilution normovolémique dans la chirurgie oncologique cervico-faciale et ORL [Place of normovolemic hemodilution in oncologic cervicofacial and ENT surgery]

OBJECTIVE: Evaluate the use of normovolaemic haemodilution in cervico-facial oncologic surgery. STUDY DESIGN: Prospective, randomised, simple blinded study. PATIENTS AND METHODS: 38 ASA I and II patients were studied: a control group (n = 21) and a haemodilution group (n = 17) in whom 5.5-8 mL.kg-1 blood were withdrawn before induction, replaced by an equivalent amount of colloids. In both groups, the transfusional strategy was to keep the haemoglobin level above 100 g.L-1 throughout the procedure and the recovery phase, using in priority the autologous blood in the haemodilution group. Blood losses during surgery were evaluated by weighing the sponges and by measuring the aspirated blood. RESULTS: Demographic and anaesthetic data, and blood losses were similar. The haemoglobin levels dropped significantly in the haemodilution group (138 +/- 10 g.L-1 to 107 +/- 11 g.L-1) as well as in the control group (131 +/- 11 g.L-1 to 110 +/- 10 g.L-1). Infectious complications were slightly higher in the haemodilution group, although this difference did not reach the level of significance. CONCLUSION: Normovalaemic haemodilution does not seem to be indicated in cervico-facial and ENT oncologic surgery