Early and late parameters describing the offset of neuromuscular blockade are highly intercorrelated.

BACKGROUND: Neuromuscular blocking agents have always shown wide inter-individual variability when it comes to their duration of action. This prevents clinicians from anticipating the evolution of the neuromuscular block for any given patient. With this study, we aimed to assess the nature of the relationships existing between different time course parameters used to describe paralysis onset and offset. METHODS: Sixty American Society of Anesthesiologists (ASA) score III-IV anaesthetised patients were randomised to receive a single equipotent dose (2ED95) of either rocuronium, mivacurium or atracurium. We used acceleromyography to monitor neuromuscular transmission. We described the relationships between the time-interval measurements of: onset, the first response (T1) reappearance, T1 25% of control, train-of-four ratio 0.25 and 0.75. Pearson correlation coefficients were calculated. RESULTS: We found no significant relationships between onset and any of the four parameters used to describe the offset. On the other hand, we showed strong and highly significant linear relationships between all the parameters describing the offset for each of the muscle relaxants studied (correlation coefficients ranging from 0.850 to 0.992). CONCLUSIONS: We evidenced strong linear correlations between the four offset time course parameters of spontaneous recovery after a single neuromuscular blocking agents (NMBAs) bolus. Such relationships open up new clinical perspectives concerning quantitative neuromuscular transmission monitoring: the scope of individual valuable anticipation of the patient's recovery.

Assessment of continuous cold blood cardioplegia in coronary artery bypass grafting.

BACKGROUND: A method of cold blood cardioplegia (CBCP) delivered continuously and in a retrograde manner was compared with methods differing only by their rate (intermittent) or way (antegrade) of administration. METHODS: This study comprises 298 consecutive patients undergoing isolated coronary artery bypass grafting procedures performed by the same surgeon from 1992 to 1995. Three-vessel disease characterized 58.8% of the cases, and the left ventricular ejection fraction was less than 0.40 in 22.8%. In group I (n = 100), CBCP was administered in an antegrade and intermittent fashion; in group II (n = 87), CBCP was given in a retrograde and intermittent manner; in group III (n = 111), CBCP delivery was retrograde and continuous. RESULTS: The incidence of major cardiac adverse outcome (death or need for intraaortic balloon counterpulsation) was 7.0% in group I, 8.0% in group II, and 0.9% in group III (p = 0.040). Repeated-measures analysis of hemodynamic indices showed a marked superiority of continuous retrograde compared with antegrade intermittent blood cardioplegia regarding left ventricular stroke work index (p < 10(-4)) and compared with both methods of intermittent CBCP regarding right ventricular stroke work index (p < 10(-5)). CONCLUSIONS: The use of continuous CBCP resulted in a significant reduction in major cardiac events, better left ventricular performance, and a marked improvement of right ventricular function in comparison with similar solutions of blood cardioplegia administered intermittently, independent of their way of delivery.

Effects of acute decrease in systemic afterload on accuracy of Doppler-derived left ventricular rate of pressure rise measurement in anesthetized patients.

OBJECTIVES: This study was designed to describe exactly the effects of acute decrease in systemic afterload on the accuracy of Doppler-derived left ventricular rate of pressure rise (LV DeltaP/Delta(t)) measurements compared with other routinely used indices of systolic function. METHODS: Twelve patients scheduled for coronary artery bypass grafting were studied. After induction of anesthesia (T0), afterload was modified by incremental administrations of nicardipine (T1-4). At each step of the procedure, thermodilution-derived cardiac index, left ventricular (LV) fractional area change, and LV DeltaP/Delta(t) were measured, and systemic vascular resistances were calculated. RESULTS: During the procedure, the systemic vascular resistances decrease averaged 13.4%. Systemic vascular resistances were correlated with LV DeltaP/Delta(t) (r = 0.843, P =.003) but inversely correlated with cardiac index (r = -0.782, P =.005) and LV fractional area change (r = -0.887, P =.003). CONCLUSION: In conclusion, and inversely to cardiac index or LV fractional area change, LV DeltaP/Delta(t) does not overestimate LV contractility in the presence of an acute decrease in systemic afterload.

Doppler-derived left ventricular rate of pressure rise determination in presence of severe acute mitral regurgitation in pigs.

Doppler-derived left ventricular (LV) rate of pressure rise (Dop LV DeltaP/Deltat) is described as an index of LV performance in the presence of mitral regurgitation (MR). This study was designed to define more accurately the accuracy of the method in the presence of severe MR. Ten pigs were anesthetized and monitored. MR was gradually created. At each grade of MR, preload was manipulated with the intent of modifying LV end-diastolic area value within a range of +/-20%. Concurrently, the mean left atrial pressure (LAP) was recorded, MR was quantified by the mitral to aortic velocity-time integral ratio (mitroaortic VTI ratio), Dop LV DeltaP/Deltat was calculated, and peak LV dP/dt was derived from LV catheterism data. During the procedure Dop LV DeltaP/Deltat gradually underestimated peak LV dP/dt. This difference was correlated to the mean LAP (P < 10(-5)) and mitroaortic VTI ratio (P < 10(-5)) and became clinically significant when the mean LAP was superior to 21 mm Hg.

TOF-tube, a new protection for acceleromyography, compared with the TOF-Guard/TOF-Watch arm board.

Neuromuscular blockade monitoring at the adductor pollicis has become easier using acceleromyography. In order to guarantee a reliable analysis of its acceleration, the thumb movement has to be free and protected from external influences. To this end, we describe here-in two hand fixation- and protection-devices for use with acceleromyography. After a bolus of 0.3 mg/kg rocuronium, we compared acceleromyography data obtained simultaneously on both hands with, on one side, the cumbersome TOF-Guard/TOF-Watch arm board, and the smaller and handier TOF-tube on the other. Results showed little differences between the two devices. Yet, a short and clinically irrelevant delay was observed for TOF-tube data during recovery. This was probably caused by a difference in thumb position and repositioning technique. In conclusion, the more convenient TOF-tube can be used as well as the TOF-Guard/TOF-Watch arm board in daily clinical practice.

Scheduling of elective surgical cases within allocated block-times: can the future be drawn from the experience of the past?

UNLABELLED: We determined a strategy to regulate the elective occupation of operating rooms; it was based on the determination of a median operating room occupation time, per procedure and per operator. METHODS: Median occupation times were determined from a retrospective analysis of 12 consecutive months of operating activity (966 patients). These data were prospectively used in surgical planning, with a daily occupation limit set at 10 hours. After four months collecting data, daily recorded (ROT) and predicted (POT) occupation times were compared. The surgical activity during that test period (group A) was compared to the activity of the same period in the previous year (group B) and the evolution of the waiting lists for surgery were analysed for each of the operators. RESULTS: At the end of the four-month observation period, 317 surgical cases spread over 105 operating days were recorded. The correlation between ROT and POT was strong (r = 0.911, p < 0.001). The relative error in this prediction was 13 +/- 11 min. In comparison with group B, group A was characterized by a significant reduction in occurrence (p = 0.015) and duration (p = 0.007) of time limit overruns and in variability of daily occupation time (p < 0.001). The waiting list was reduced for all operators at the end of the test period. CONCLUSION: Determination of individualized median occupation times, associated with definition of a daily limit, resulted in reduction of time overruns and delays before surgery.

Beating heart surgery using the Octopus tissue stabilizers: initial experience including triple vessel disease and high-risk patients.

OBJECTIVE: The aim of this study was to evaluate initial results in beating heart coronary artery bypass grafting performed on patients with multivessel disease, using suction-based tissue stabilizers. METHODS: Forty patients (mean age 65.5 years, range 39-83) underwent beating heart coronary bypass by median sternotomy, with the use of the Octopus 1 (n = 27) and Octopus 2 (n = 13) devices. Twenty patients had unstable angina, four had pulmonary oedema, and four required preoperative intra-aortic balloon counterpulsation. Five interventions were repeat procedures. Mean ejection fraction was 54.4%(range 20-82%). Eighteen patients had triple-vessel disease, 18 patients had double-vessel disease and > 50% left main stem stenosis was present in six patients (isolated or in association). The average number of distal anastomoses was 2.5 (range 1-5, total 101). A mean of 1.5 (range 1-3) anastomoses was achieved with arterial grafts (45 mammary and 12 gastroepiploic arteries). RESULTS: Immediate graft patency was evaluated by Doppler flowmeter and five anastomoses were successfully corrected, based on an occlusion pattern. The perioperative myocardial infarction rate was zero. Transient episodes of supraventricular arrhythmias were detected in 19 patients. The administration of dobutamine at an inotropic concentration > 5 gamma-1 kg-1 min-1 was required in one patient. There were two in-hospital deaths (one non-cardiac-related). Overall survival and cardiac event-free rate at 20 months were 92.4% +/- 4.2% and 81.8% +/- 11.6%, respectively. CONCLUSIONS: Satisfactory results can be achieved in multivessel disease high-risk patients with beating heart coronary bypass surgery.

Persistent left superior vena cava: transoesophageal echocardiographic findings and surgical strategies.

Two cases of casual discovery of persistent left superior vena cava during cardiac surgery are reported. Diagnoses were suspected at the time of peroperative transoesophageal echocardiography in the first case, and of preoperative fluoroscopy during a Swan-Ganz catheter insertion procedure in the second case. For both patients, a peroperative echo contrast study permitted to confirm the anomaly before initialization of cardiopulmonary bypass. Embryology, echocardiographic findings and surgical management, including cardioplegia delivering and left upper venous system drainage, are reviewed.

Patent foramen ovale and implantable cardioverter defibrillator.

A case of patent foramen ovale opening was observed concomitantly to a defibrillation threshold determination in the setting of an internal cardioverter defibrillator implantation. The subsequent transient right-to-left shunt was confirmed by a peroperative transoesophageal echocontrast study. The underlying mechanism of this incident may be related to a transient reversal of the interatrial gradient, due to the pre-existence of pulmonary hypertension and tricuspid regurgitation, associated with ongoing mechanical ventilation and modifications of intracardiac pressures regimen secondary to the succeeding ventricular tachyarrhythmia and defibrillation. Paradoxical embolism can be an aetiology for neurologic injury during internal cardioverter defibrillator implantation.

[Anaesthesiologic implications of the radial approach in interventional cardiology]. / Implications anesthésiologiques de l'abord radial en cardiologie interventionnelle.

The development of the radial approach in interventional cardiology is one of the reasons for the increase in demands for anaesthesia services in the cardiac catheterization room. The technique in which sedation is carried out in this particular environment has gradually changed, in parallel with the development of new technologies in anaesthesia, particularly suited to achieving short sedation in spontaneous ventilation. This article evaluates this issue and suggests an updated therapeutic approach.

Propofol-alfentanil versus fentanyl-midazolam in coronary artery surgery.

OBJECTIVE: To compare intraoperative hemodynamics profiles and recovery characteristics of propofol-alfentanil with fentanyl-midazolam anesthesia in elective coronary artery surgery. DESIGN: Prospective, randomized study. SETTING: University hospital. PARTICIPANTS: Fifty patients with impaired or good left ventricular function. INTERVENTIONS: In group 1, (n = 25) anesthesia was induced with an infusion of propofol, 3 to 4 mg/kg/h, alfentanil, 500 micrograms, and pancuronium 0.1 mg/kg, and maintained with propofol, 3 to 6 mg/kg/h (variable rate), and alfentanil infusions, 30 micrograms/kg/h (fixed rate). Additional boluses of alfentanil, 1 mg, were administered before noxious stimuli; group 2 (n = 25) received a loading dose of fentanyl, 25 micrograms/kg, midazolam, 1.5 to 3 mg, and pancuronium, 0.1 mg/kg for induction, followed by an infusion of fentanyl, 7 micrograms/kg/h, for maintenance. Additional boluses of midazolam (1.5 to 3 mg) and fentanyl (250 micrograms) were administered before noxious stimuli. MEASUREMENTS AND MAIN RESULTS. Cardiovascular parameters at eight intraoperative time points as well as time to extubation, morphine consumption, and pain scores were recorded. Induction of anesthesia was associated in both groups with a small but significant decrease in mean arterial pressure (1: 15 mmHg (15%); 2: 8 mmHg (8%) with significant decreases in cardiac index (1: 8%; 2: 8%) and left ventricular stroke work index (1: 24%; 2: 21%). Throughout surgery, hemodynamic profiles were comparable between groups except after intubation when the MAP was significantly lower in group 1 (75 +/- 12 mmHg) than in group 2 (89 +/- 17 mmHg). Group 1 required less inotropic support. Extubation was performed faster in group 1 (7.6 h) than in group 2 (18.0 h). Morphine requirements and pain scores were comparable between groups. CONCLUSIONS: Propofol-alfentanil anesthesia provides good intraoperative hemodynamics and allows early extubation after coronary artery surgery.

Doppler-derived left ventricular rate of pressure rise and inotropic requirements during mitral valve surgery.

BACKGROUND: The estimation of left ventricular (LV) contractility is difficult in the presence of significant mitral regurgitation (MR). Prediction of LV performance after MR repair is even more problematic. The intraoperative Doppler-derived LV rate of pressure rise (LV delta P/delta t) analyzed before cardiopulmonary bypass (CPB) was presumed to be a useful predictive parameter for LV performance. Therefore, its relation to perioperative inotropic requirements (PIR) necessary for separation from CPB after surgical MR repair was investigated. METHODS: Twenty-eight patients scheduled for surgical MR repair fulfilled the selection criteria. Pre-CPB LV delta P/delta t, pre-CPB echocardiographic LV fractional area change (LV FAC), and pre-CPB thermodilution-derived cardiac index (CI) were recorded. After MR repair, separation from CPB was performed with regard to standardized guidelines. PIR during the first 60 minutes following separation were recorded. RESULTS: Pre-CPB LV delta P/delta t could be assessed in 22 patients. Pre-CPB LV delta P/delta t was 882 +/- 450 mmHg/sec, pre-CPB LV FAC was 49% +/- 9%, and pre-CPB CI was 2.0 +/- 0.2 L/kg/min. Pre-CPB LV delta P/delta t was significantly correlated with pre-CPB LV FAC (r = 0.56), and with pre-CPB CI (r = 0.72). Inotropic support was necessary in 16 patients (73%), and was best predicted by the pre-CPB LV delta P/delta t, by means of logistic regression (p = 0.026). CONCLUSIONS: Doppler-derived LV delta P/delta t was assessable in most patients with severe chronic MR, and was the best intraoperative predictive parameter of post-CPB inotropic requirements after surgical MR repair.

Hemodynamic benefit of optimizing atrioventricular delay after cardiopulmonary bypass.

BACKGROUND: Shortening of atrioventricular delay (AVD) by sequential cardiac pacing has been proposed to improve hemodynamics in patients with end-stage heart failure. In addition, optimization of prolonged AVD may be associated with a decrease of presystolic mitral insufficiency. The aim of this study was to explore the incidence of prolonged AVD during the early postcardiopulmonary bypass (CPB) period and to evaluate the hemodynamic benefit of its shortening by using sequential cardiac pacing. METHODS: Fifty consecutive patients scheduled for coronary artery bypass grafting were prospectively screened. AVD was measured immediately after separation from CPB. Patients presenting with AVD greater than or equal to 200 ms entered the study. Sequential cardiac pacing was introduced with programmed AVD starting at 80 ms and randomly increased by steps of 20 ms until resumption of native anterograde atrioventricular node conduction. Cardiac index (CI) was derived from transesophageal echocardiographic data during each step of this procedure. RESULTS: Nineteen patients were included. Median native AVD was 220 ms. Median optimal AVD was 140 ms. Mean native CI (CI-nat) was 2.59 +/- 0.42 L/min/m2. Mean optimal CI (CI-opt) was 3.12 +/- 0.45 L/min/m2. CI-opt/CI-nat was 1.20 +/- 0.07. CI-opt/CI-nat was significantly inversely correlated with preoperative left ventricular ejection fraction (r = -0.83). CONCLUSIONS: Prolonged AVD is a common occurrence after CPB. Its artificial shortening by sequential cardiac pacing is always associated with a significant increase of CI. The magnitude of this hemodynamic improvement is inversely correlated with preoperative left ventricular ejection fraction.