CT angiography for brain death diagnosis.

BACKGROUND AND PURPOSE: Lack of cerebral circulation is an important confirmatory test for brain death (BD). Conventional angiography remains the standard imaging method, but CT angiography (CTA) is emerging as an alternative. France accepts BD diagnoses relying on a score based on lack of opacification of 7 intracerebral vessels in CTA images. The purpose of this study was to validate the efficiency of this score and to evaluate the sensitivity of a novel 4-point CTA score in confirming BD. MATERIALS AND METHODS: A prospective multicentric study was conducted during 12 months with 105 patients referred for CTA to confirm a clinical diagnosis of BD. Clinical data were recorded. CTA images were interpreted first by local radiologists at the referent center, resulting in a 7-point score based on lack of opacification of the pericallosal and cortical segments of the middle cerebral arteries (MCAs), internal cerebral veins (ICVs), and 1 great cerebral vein per patient and, second, by a consensus panel of 3 expert radiologists, blinded to the initial scores, resulting in novel 4-point scores based on the lack of opacification of the cortical segments of the MCAs and ICVs. RESULTS: Injection of contrast medium did not alter renal function. With the initial 7-point score, sensitivity was 62.8%. With the simplified 4-point score, sensitivity was 85.7% and specificity was 100%. Opacification of ICVs was absent in 98.1% of patients. CONCLUSIONS: Lack of opacification in the cortical segments of the MCAs and internal veins in CTA is efficient and reliable for confirming BD.

Partial anomalous pulmonary venous connection: correction by intra-atrial baffle and cavo-atrial anastomosis.

The creation of intracaval conduits to repair partial anomalous pulmonary venous connection of the right lung into the superior vena cava can be complicated by arrhythmias and superior vena cava and pulmonary vein obstruction. An intra-atrial baffle, combined with cavo-atrial anastomosis, has been proposed to avoid these complications. The authors report their recent experience with this operative technique. From January 1997 to December 2000, 7 patients with a mean age of 13.5 +/- 9 (2-31) years were operated according to this technique. Only one child did not have an associated atrial septal defect. The mean number of pulmonary veins connected to the superior vena cava was 2.5 +/- 0.5. The immediate postoperative course was uneventful for the seven patients. The mean follow-up was 20 +/- 17 months. No patient developed arrhythmia or superior vena cava or pulmonary vein obstruction at echocardiography. This surgical technique appears to constitute an attractive alternative when pulmonary veins drain abnormally into the superior vena cava above the cavo-atrial junction.

[Pulmonary and cardiopulmonary transplantation in mucoviscidosis]. / Transplantation pulmonaire et cardiopulmonaire au cours de la mucoviscidose.

As early as 1987, several teams in France began lung transplantation for patients with cystic fibrosis. Most of these teams propose transplantation when the life expectancy is under 2 years. The major functional criteria are VEMS < 30%, PaC02 > 50 mmHg and PaO2 < 55 mmHg. This contribution focuses on psychologic, nutritional and infectious aspects required in preparing the patients for transplantation and on graft selection. Surgical techniques and patient care after transplantation are also reported. The overall probability of survival after transplantation for cystic fibrosis is 48, 35 and 29% at 1, 2 and 3 years respectively with wide intercentre variation. The lack of sufficient graft supply and the risk of post-transplantation degradation remain the two principal problems for transplantation in cystic fibrosis.

Dose-related effects of isoflurane associated with low plasma concentrations of verapamil on global and regional function in normal and compromised canine myocardium.

Global and regional myocardial functions were studied in seven open-chest dogs with constant low plasma concentrations of verapamil as increasing concentrations of isoflurane (0.75, 1, 1.5 MAC) were administered in the presence of normal myocardial perfusion and after application of critical constriction of the left anterior descending coronary artery. In the presence of verapamil, increases in isoflurane concentrations caused dose-dependent myocardial depression both before and after critical coronary constriction. The systemic and coronary vasodilatation associated with high concentrations of isoflurane did not occur in the presence of verapamil. The association of verapamil with isoflurane caused regional myocardial dysfunction that worsened at high isoflurane concentrations. This regional dysfunction could not be antagonized in two dogs. The effects of isoflurane on regional function were not modified by application of a critical coronary constriction.

[Inotropic and vasopressive drugs during anesthesia and critical care. Current data]. / Inotropes et vasopresseurs en anesthésie-réanimation. Actualités.

Recent therapeutic advances in inotropic drugs and vasipressors uses allow a reappraisal of their indications during the perioperative period. Non-catecholamines vasopressors, ephedrine and phenylephrine, are particularly suitable for treatment of abrupt peroperative arterial hypotensions as observed during induction of general and medullar anesthesias. Cardiac arrest, peroperative anaphylactoid and toxic accidents are treated with epinephrine. In non-cardiac surgery, circulatory insufficiency is usually due to a peripherical origin. Cardiogenic failure occurs in rare cases mainly in vascular surgery. Therefore dopamine remains the first amine to be used in non-cardiac surgery in conjunction with volume expansion. A cardiogenic factor is responsible for most of low-cardiac output syndromes observed after cardiopulmonary bypass for cardiac surgery. However, hypovolemia may be involved and could be undiagnosed. For these reasons, dobutamine is used because of its rapid half-life of elimination and its potent effects. Inodilators (enoximone, amrinone and milrinone) ans nex dopaminergic compound (dopexamine) are powerful vasodilators agents to be introduced with care when association of amines and current vasodilators have failed. Finally, arterial pressure has to be maintained with norepinephrine after dopamine failure. Epinephrine remains last chance.

[Dose-dependent vasodilator effect of dobutamine in calves with a constant cardiac output artificial heart]. / Effet vasodilatateur dose-dépendant de la dobutamine chez le veau sous coeur artificiel à débit cardiaque constant.

The haemodynamic effect of any drug being the resultant of its myocardial and vascular actions, it is often difficult to separate what is due to each of these components. Dobutamine is regarded as having an almost exclusive effect on the myocardium in therapeutic doses (1); its administration after implantation of an artificial heart would enable its peripheral vascular effects to be determined by exclusion of the native ventricles. Experiments were conducted on three calves weighing about 90 kg each. The artificial heart, two central venous catheters and a femoral arterial catheter were implanted under general anaesthesia. The study began on the first post-implantation day, the animals being awake, in stable haemodynamic status and with normal temperature. Dobutamine was infused through one of the venous catheter placed in the native atrium, in 6 stepwise doses of 5, 10, 15, 20, 25 and 30 mcg/kg/min, each dose being given over 10 min and separated from the other dose by a 10 min interval. The order in which these doses were administered was determined at random. By adjusting the propulsion pressure of the two ventricles and the heart rate, the cardiac output was set at a fixed value of 7.85 L/min throughout the study, this value being controlled by a computer-assisted unit. Right atrial pressure and femoral arterial were recorded during each step of the infusion. Total peripheral resistance was calculated over a stable period of the last 5 min of each dosing and before administration of dobutamine. This procedure was repeated 4 times in each calf, at intervals of 24 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

[What is the role of monitoring of mixed venous blood saturation in cardiac surgery?]. / Quelle est la place du monitorage de la saturation du sang veineux mêlé en chirurgie cardiaque?

The equipment available for mixed venous blood saturation (Svo2) monitoring is now accurate. SvO2 is not a direct measure of cardiac output, because it depends on the balance between oxygen delivery (TaO2) and consumption (VO2). As haemoglobin affinity for oxygen increases during cardio-pulmonary bypass (CPB), the optimal level of SvO2 after CPB should be above 65-70%. There is a critical level of TaO2 below which VO2 is dependent on TaO2. Below this level, SvO2 has no clinical value as it no longer depends on TaO2. Similarly, SvO2 has no clinical value during lactic acidosis. When these limitations are taken into account, SvO2 monitoring is useful for the interpretation of intra- and post-operative haemodynamic alterations occurring during cardiac surgery. It is particularly indicated in patients with preoperative NYHA class III or IV congestive heart failure.

[Difficult catheterization of the radial artery. Comparison of a new arterial catheter and Seldinger's technic]. / Cathétérisme difficile de l'artère radiale. Comparaison d'un nouveau cathéter artériel avec la technique de Seldinger.

Sixty difficult radial artery cannulations were carried out using either the Seldinger technique (Seldicath Plastimed, FG 3, 80 mm long; group S; n = 30) or a new arterial catheter (Arrow, Critikon, gauge 20, 44 mm long; group A; n = 30) in patients scheduled for coronary arterial surgery or cardiac valve replacement (age: 54.8 +/- 11.8 yr). The technique was chosen at random after failure of radial artery catheterization with a short intravenous catheter (Quick-Cath Travenol, gauge 20, 31 or 51 mm long, or Insite W Beckton-Dickinson, gauge, 20, 30 mm long). The second attempt was carried out on the same artery, a few centimeters higher up than the first one. Heparinized normal saline was infused through this arterial line. All the catheters were removed after extubation. There was no arterial thrombosis, nor any displacement of the catheter with loss of the arterial pressure curve. No difference was found between the two techniques regarding the number of catheterization failures, the duration of cannulation, and the quality of the blood pressure curve. For difficult radial artery cannulations, the arterial catheter Arrow associated the advantages of the Seldinger technique with those of short intravenous catheters.

[Hemodynamic effects of fentanyl and sufentanil combined with flunitrazepam in coronary artery surgery]. / Effets hémodynamiques du fentanyl et du sufentanil associés au flunitrazépam lors de la chirurgie coronarienne.

Because sufentanil has been reported as being able to prevent or treat peroperative hypertensive crises during aorto-coronary artery graft surgery, a study was carried out to compare the haemodynamic effects of sufentanil with those of fentanyl. 20 patients who were to undergo aortocoronary bypass grafting (CABG) were randomly allocated to two equal groups, sufentanil (Sf) and fentanyl (F) groups. A 1 to 5 dose ratio was used so as to have equipotent doses of sufentanil and fentanyl. Induction doses were 10 micrograms.kg-1 sufentanil and 50 micrograms.kg-1 fentanyl. Up to 20 micrograms.kg-1 sufentanil and 100 micrograms.kg-1 fentanyl were then used between intubation and the setting-up of cardiopulmonary bypass (CPB). A bolus of 10 micrograms.kg-1 flunitrazepam was given if necessary, so as to lower the mean arterial pressure (Pa) to below 100 mmHg after intubation, and under 80 mmHg during CPB. Heart rate, Pa, mean pulmonary arterial pressure, pulmonary wedge pressure (Ppw), central venous pressure and cardiac output were measured before anaesthesia, 2 min after intubation, before incision, 2 min after sternotomy, 10 min after the end of CPB, after chest closure, 30 min and 2h after arrival of the patient in the intensive care unit. The only difference found between the two groups was a more rapid drop in left ventricular preload after induction with sufentanil; 2 min after intubation, there was a 26% fall in Ppw with sufentanil (p less than 0.01) and 8% with fentanyl. Before skin incision, this drop was of 32% (p less than 0.01) and 24% (p less than 0.01) respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The association isoflurane-verapamil causes regional left-ventricular dyssynchrony in the dog.

In ten dogs anesthetized with 1% inspired isoflurane, the effect of low-dose verapamil on global and regional myocardial function was studied. The administration of verapamil resulted in no change in heart rate or blood pressure, but left ventricular stroke work, peak power, LV dP/dt max, and aortic blood acceleration were significantly reduced, while coronary blood flow remained unchanged. End-diastolic length increased in territory supplied by both left anterior descending (LAD) and left circumflex (LC) artery, but a significant decrease in systolic shortening occurred in the LAD segment only. Dyssynchrony of wall motion, characterized by post-systolic shortening, accompanied in three animals by a small amount of systolic lengthening, appeared with the administration of verapamil and was more pronounced in the LAD segment. Such patterns of wall motion have usually been attributed to myocardial ischemia. In the absence of significant reduction in coronary blood flow, and in the presence of a delay in onset of shortening and lengthening, these patterns of wall motion are more likely to reflect dyssynchrony of regional function than ischemia.

Effects of droperidol on peripheral vasculature: use of cardiopulmonary bypass as a study model.

The effects of droperidol on the systemic vascular resistance (SVR) and the venous capacitance were studied during cardiopulmonary bypass (CPB) in 24 patients. CPB was performed with either pulsatile or non-pulsatile flow. During non-pulsatile flow, droperidol (0.15 mg X kg-1 and 0.30 mg X kg-1) decreased SVR and increased venous capacitance. These values were significantly different after the 2nd and the 7th min, respectively. During pulsatile flow, the initial SVR was lower. The decremental effect of 0.30 mg X kg-1 droperidol on SVR was proportional to the preinjection level of SVR (r = 0.64). The increase in venous capacitance related to droperidol was independent of the dose and of the type of flow in all patients. It can be concluded that the vasodilating action of droperidol during CPB on the arterial bed is transient, independent of dose, and related to the preinjection level of SVR. The effect of droperidol on venous capacitance is not as rapid but has a longer duration.

Oral intubation v. nasal intubation in adult cardiac surgery.

Time for intubation, incidence of mechanical complications, occurrence of bacteraemia caused by intubation, and postoperative discomfort were assessed in relation to nasal and oral tracheal intubation in adult cardiac surgery. The time for placement of the tube was 2.5 times longer for nasal intubation. Nasal bleeding was observed in 45.3% of patients intubated through the nose. In patients in whom a naso-tracheal tube was passed, 9.4% (v. 2.3% of patients intubated via the mouth), exhibited positive blood cultures just after intubation; however, the difference was not significant. Postoperative discomfort was similar in both groups. It can be concluded that nasal tracheal intubation offers no advantage over oral tracheal intubation in adult cardiac surgery.

[Enflurane and extracorporeal circulation. Peripheral vascular effects and consequences of hypothermia on its biotransformation]. / Enflurane et circulation extracorporelle. Effets vasculaires périphériques et conséquences de l'hypothermie sur sa biotransformation.

The effects of enflurane on systemic vascular resistance and venous capacitance, and its biotransformation during hypothermia, were studied in patients undergoing cardiovascular surgery with enflurane anaesthesia. When administered during cardiopulmonary bypass (CPB), cardiac regulatory mechanisms being therefore excluded, enflurane induced an arteriolar vasodilation related to the concentration inhaled. An inspired concentration of 2.5% in hypothermia (28 degrees C) produced a drop in systemic vascular resistance of 30% from control level. In the same conditions, venous capacitance was not altered. The rise in the blood gas solubility coefficient during hypothermia was only partly balanced by haemodilution. Therefore, inspired enflurane concentration should be higher during hypothermic CPB than during normothermic anaesthesia to obtain the same effects. For the same amount of enflurane inhaled, the fraction of enflurane metabolized was higher in hypothermia than in normothermia, but the inorganic fluoride plasma concentration at its highest never reached the level of 50 mumol X 1(-1) regarded as the nephrotoxic threshold.

[Preoperative measurement of blood volume in patients before undergoing an aortocoronary bypass]. / Mesure préopératoire de la volémie chez les patients devant subir un pontage aorto-coronarien.

Preoperative measurement of blood volume was performed in 35 patients undergoing coronary arterial bypass grafts. The patients were divided in two groups according to the preoperative blood volume measurement : normal (group I) and decreased (group II) blood volume. Cardiac filling pressures were measured with a Swan-Ganz catheter prior to induction of anaesthesia in all patients. Pulmonary capillary wedge pressure was significantly decreased in patients with diminished blood volume. Clinical data was compared between the two groups. No differences were found regarding preoperative cardiovascular drugs and severity of coronary arterial disease. The only differences between the two groups were : 1) the length of preoperative hospitalization was significantly longer for hypovolaemic patients (21 +/- 10 days) than for normovolaemic patients (3 +/- 6 days); 2) more group II patients (13 of 15) received a salt-restricted diet than group I patients (2 of 20). Diet induced hypovolaemia may increase the rate of large haemodynamic variations produced by induction of anaesthesia in patients with coronary arterial disease. Seeing the frequency of preoperative hypovolaemia in patients undergoing coronary arterial surgery, we recommend the preoperative measurement of blood volume in these patients and preanaesthetic fluid replacement when hypovolaemia is present.