Diagnosis by intraoperative transesophageal echocardiography of acute thrombosis of mechanical aortic valve prosthesis associated with the use of biological glue.

Mechanical aortic valve thrombosis is an uncommon complication of valve replacement. Inadequate anticoagulation is observed in 45% of patients presenting with this complication and it occurs as close as 15 days postoperation (1). Failure to wean from cardiopulmonary bypass (CPB) after aortic valve replacement may be because of a multitude of pathologies. We present a case where easy access to transesophageal echocardiography (TEE) allowed a rapid diagnosis of acute mechanical aortic valve occlusion with subsequent successful surgical management.

The use of transesophageal echocardiography for preload assessment in critically ill patients.

UNLABELLED: IV volume is often administered to patients in an intensive care unit (ICU) to improve cardiovascular function. We investigated the relationship between stroke volume (SV) and left ventricular (LV) size by using transesophageal echocardiography (TEE) in a population of 20 ICU patients and 21 postoperative cardiac surgical patients. We also examined whether LV end diastolic area (EDA), by TEE, could identify patients who increased SV by 20% or more (responders) after 500 mL of pentastarch administration. There was only a modest relationship (r = 0.60) between the EDA and the SV in all patients. No relationship could be found between the pulmonary capillary wedge pressure (PCWP) and the EDA in all patients. Both responder and nonresponder PCWP increased significantly after volume administration. Only responder EDA increased significantly after volume administration. Responders had significantly lower EDA (15.3 +/- 5.4 cm(2)) and PCWP (12.2 +/- 2.2 mm Hg) when compared with nonresponders (20.2 +/- 4.8 cm(2)) and 15.9 +/- 3.1 mm Hg, respectively). Few ICU patients and only those with a small EDA responded to volume administration. It was not possible to identify an overall optimal LV EDA below which most patients demonstrate volume-recruitable increases in SV. IMPLICATIONS: In a ventilated intensive care unit and cardiac surgical population, transesophageal echocardiography and pulmonary artery catheter are sensitive in detecting changes in preload after volume administration. Few patients demonstrate volume-recruitable increases in stroke volume when compared to cardiac surgical patients. It is not possible to establish an overall end diastolic threshold below which a large proportion of ventilated patients respond to volume administration.

Acute quadriparesis in an asthmatic treated with atracurium.

An 18-yr-old male asthmatic was paralyzed with atracurium for a period of seven days to facilitate mechanical pulmonary ventilation. After withdrawal of the muscle relaxant, train-of-four neuromuscular monitoring demonstrated rapid recovery of normal function. Three days later he developed acute quadriparesis without respiratory compromise. Electrophysiological studies showed normal conduction velocities, low compound muscle action potential amplitudes and evidence of denervation. Most cases of post-ventilatory weakness in the ICU involve the use of vecuronium and pancuronium. It has been suggested that the steroid nucleus in these muscle relaxants may be responsible. Our patient developed generalised weakness after treatment with atracurium, a benzylisoquinolinium muscle relaxant. Thus, it appears that the steroid nucleus of vecuronium and pancuronium is not essential in causing post-ventilatory weakness.

Alfentanil controls the haemodynamic response during rapid-sequence induction of anaesthesia.

Laryngoscopy and tracheal intubation often cause hypertension and tachycardia, which may be exaggerated during rapid-sequence induction of anaesthesia. A placebo-controlled, double-blind study was conducted in 60 patients to determine dose-response and effects on myocardial performance of alfentanil when used to attenuate this cardiovascular response. Patients were divided into four groups to receive a pre-induction bolus from a coded syringe, which contained either normal saline (PLAC), alfentanil 30 micrograms.kg-1 (ALF 30), alfentanil 45 micrograms.kg-1 (ALF 45) or alfentanil 60 micrograms.kg-1 (ALF 60). Anaesthesia was induced in rapid sequence with thiopentone 4.0 mg.kg-1 and succinylcholine 1.5 mg.kg-1, and the trachea was intubated 60 sec later. Increases in heart rate (21 +/- 10 bpm), mean arterial pressure (28 +/- 13 mmHg), and systemic vascular resistance index (1420 +/- 780 dynes.sec-1.cm-5) were observed in response to intubation with PLAC but in none of the 3 ALF groups (P less than 0.05). However, heart rate and mean arterial pressure decreased significantly in both the ALF 45 and ALF 60 groups (P less than 0.05), whereas ALF 30 resulted in no change in these variables over time. Cardiac index, stroke volume index, and ejection fraction tended to decrease in all four groups, but none of these variables was different at corresponding time when comparing the ALF groups with PLAC.(ABSTRACT TRUNCATED AT 250 WORDS)