Fourrier analysis demonstrate EEG slowing after circulatory arrest at 20 degrees C.

The electroencephalographic (EEG) monitoring in infants and children submitted to cardiac surgery under circulatory arrest (CA) and deep hypothermia (20 degrees C) (DH) is usually performed by display or record without analysis. These data disclose the reappearance of EEG activity but give no qualitative analysis of EEG recovery after CA. The electrical activity of the brain was monitored in these conditions by spectral analysis (fast Fourrier transformation with on-line processing). Spectral analysis of the EEG signal recorded during open heart surgery in nine infants and children operated under DH with, in five cases, CA is presented and discussed. The Fourrier analysis demonstrate in all patients with long CA (more than 30 min.) a spectral abnormality, namely the absence of fast activity (8-24 Hz) at least for the remainder of the operation. This abnormality was not present in operations without CA and was only transient after CA of shorter duration.

Haemodynamic effects of midazolam in the anaesthetized patient with coronary artery disease.

The haemodynamic effects of midazolam 0.25 mg/kg administered intravenously were studied in eight anaesthetized patients suffering from coronary artery disease. Heart rate, systemic and pulmonary pressures, right atrial pressure, capillary pressure and cardiac output were measured 2, 5, 8 and 12 min after injection of midazolam and were compared with reference values collected before the commencement of the haemodynamic test. The cardiovascular condition of all the patients followed the same course after the injection of midazolam. The greatest variations were seen at the twelfth minute, with the exception of capillary pressure where the largest decrease was noted at the eighth minute. These variations, expressed as a percentage of the initial values, were: mean arterial pressure -17% (P less than 0.01); capillary pressure -23.5% (eight minute, P less than 0.01); heart rate - 9% (P less than 0.01); cardiac index -9% (P less than 0.01); systemic vascular resistance -12% (eighth minute, P less than 0.01). The stroke volume was well maintained (+0.1% NS). These haemodynamic variations were accompanied by a favourable evolution of the endocardial viability ratio (EVR), +12% (P less than 0.01). The slight tachycardia occasionally seen on induction of anaesthesia with midazolam was not seen in this group of patients. We conclude that these haemodynamic variations leading to an increase in EVR support the use of midazolam as a supplement to fentanyl anaesthesia for patients with coronary artery disease.

Anesthesia with flunitrazepam and fentanyl supplemented with droperidol or chlorpromazine (Largactil) in coronary surgery.

Sixty coronary patients undergoing aortocoronary bypassgrafts, some with left ventricular resection and some with associated valvular surgery were anesthetised with flunitrazepam, pancuronium and fentanyl according to systolic blood pressure (SBP) and heart rate (HR). When 40 micrograms kg-1 fentanyl was amounted, a neuroleptic was added to the protocol either droperidol (D series, 30 cases), or chlorpromazine (L series, 30 cases), 0.005 mg kg-1 at random, if the SBP remained above 100 mm Hg or when the mean BP rose during the ECC at constant flow. Analgesia was maintained adding 0.05 mg fentanyl to each 2.5 mg neuroleptic dose. A stable cardiovascular state was achieved during the entire procedure in both series. Total doses were 53.25 +/- 10 mukg-1 (D) and 49.45 +/- 6.46 micrograms kg-1 (L) fentanyl, 0.5 +/- 0.25 microgram kg-1 droperidol and 0.38 +/0 0.032 mg kg-1 chlorpromazine. The large dispersion in the doses of neuroleptics was due to a few cases of resistance to their action during ECC. A low dose of neuroleptic (less than 0.4 mg kg-1) was sufficient in a statistically different number of patients in each series, 23 patients were given 0.25 +/- 0.1 mg kg-1 chlorpromazine and only 9 patients were given 0.23 +/- 0.11 mg kg-1 droperidol. This is thought to be due to the longer duration of action of chlorpromazine. All patients came off bypass easily. No low output state developed. During the postoperative period hypertension was not a problem when taking into account that hypertensive patients were not excluded. Thirteen patients in each series had a HR greater than or equal to 100 b.p. m. during more than 1 h, but longer after chlorpromazine (n.s.). There was no other difference in the course of the 2 series until discharge. These results prompt us to continue using droperidol because of its more satisfactory pharmacokinetic characteristics.

Hypothermia and etomidate. Electroencephalographic aspects.

Etomidate 0.3 mg/kg was injected in 30 seconds to patients submitted to coronary surgery under ECC (output = 2.4 l/min/m2) and moderate hypothermia (29 degrees). The effect of this injection on the EEG was investigated in 3 patients by the traditional EEG monitoring (bipolar fronto-parietal derivation) as well as in 12 patients by the Berg-Fourier spectral analysis. At 29 degrees C etomidate induces an EEG depression in the form of burst suppression periods of 3 to 10 seconds lasting for about 4 minutes. After etomidate injection, the electric activity measured between 0.5 Hz and 32 Hz in 7 patients remained for 4.5 minutes (+/- 1.5 min.) lower than 20% of the value noted prior to the injection. The significance of this important EEG decrease as well as the possible protective effect of etomidate against cerebral anoxia are discussed.

Analgesic anesthesia with fentanyl (F) and sufentanil (SF) in coronary surgery. A double blind study.

The study includes 54 unselected coronary patients. Fifty underwent one or several aortocoronary bypass associated with left ventricular resection (3 times), mitral valve replacement (twice), aortic valve replacement (twice). Four patients underwent left ventricular resection alone. The operations were performed under analgesic anesthesia with sufentanil (SF) or fentanyl (F) with a double blind protocol. The ratio of concentrations of the two analgesics was SF/F = 1/10. Flunitrazepam induced and maintained sleep. After having reached by increments the total dose of 1.5 mg F/M2 or 0.15 mg SF/M2, droperidol was then added in small amounts of 3.75 mg/M2, alternating with the analgesic both being given as needed to maintain blood pressure between 100 and 120 mm Hg, in order to potentiate the level of analgesia reached and prevent vasoconstriction. Under this setting tachycardia (heart rate greater than 100 beats/min. and less than 120 beaths/min.) was observed before ECC in only 7.4% of cases with both analgesics and brief episodes of hypertension (mean maximum systolic blood pressure 140.7 +/- 20.3 mm Hg seen with SF exclusively). There was neither postoperative hypertension (except with 6 out of the 7 known hypertensive patients) nor low cardiac output, nor arbythmia. No patients remained in intensive care unit more than 24 hour. No difference attribuable to the used analgesic was detectable in the early and late follow-up in both series. On an average, the patients were discharged on postoperative day 10 in a valid condition.

A comparative study of etomidate and methohexital as induction agents for analgesic anesthesia.

Two hundred current surgical procedures were done in adult patients using neuroleptanalgesia with either methohexital (1 mg/kg) or etomidate induction (0.3 mg/kg) in half of the cases. The cardiovascular function was less altered with etomidate (less occurrence of tachycardia, blood pressure drops or systolo-diastolic pinching). The etomidate dosage chosen more often gave an immediate satisfactory sleep. However, with methohexital induction, less signs of awakening were observed during the surgical procedure. The frequent postoperative somnolence also points, although indirectly, to a longer residual effect of the barbiturate. Both drugs sometimes gave erythema. The injection of etomidate was more frequently painful in the arm. On the other hand, hiccups occurred with methohexital induction only. Etomidate induced myoclonia in one-third of the cases premedicated with diazepam and after preliminary injection of a minimal amount of fentanyl. Without these precautions, myoclonia can occur in two-thirds of the patients. However, these myoclonia are bothersome and of prolonged duration in rare instances and would be of real annoyance only when this drug would be used alone for surgical procedures of short duration where perfect patient immobility is required. We therefore conclude and confirm that etomidate is a good induction agent for neuroleptanalgesia anesthesia procedures.

Comparison between fentanyl and morphine for use in analgesic anesthesia during open heart surgery.

One hundred unselected adult cardiac patients operated on with extracorporeal circulation (ECC) underwent analgesic anesthesia. In half of the cases, the analgesic used was morphine and for the others fentanyl. Anesthesia was completed with flunitrazepam, pancuronium, nitrous oxyde and a neuroleptic if necessary. Operative, postoperative and recuperation periods were very satisfactory and very the same in both series. Due to its small administrated dosage (average 1.22 mg/kg) the secondary effects of morphine remained discrete. Although its long action suits well the concerned type of surgery there seems to be no reason to prefer it to fentanyl.