Pulmonary and caval flow dynamics after total cavopulmonary connection.

OBJECTIVE: To assess flow dynamics after total cavopulmonary connection (TCPC). DESIGN: Cross-sectional study. SETTING: Aarhus University Hospital. PATIENTS: Seven patients (mean age 9 (4-18) years) who had previously undergone a lateral tunnel TCPC mean 2 (0. 3-5) years earlier. INTERVENTIONS: Pressure recordings (cardiac catheterisation), flow volume, and temporal changes of flow in the lateral tunnel, superior vena cava, and right and left pulmonary arteries (magnetic resonance velocity mapping). RESULTS: Superior vena cava flow was similar to lateral tunnel flow (1.7 (0.6-1.9) v 1. 3 (0.9-2.4) l/min*m2) (NS), and right pulmonary artery flow was higher than left pulmonary artery flow (1.7 (0.6-4.3) v 1.1 (0.8-2. 5) l/min*m2, p < 0.05). The flow pulsatility index was highest in the lateral tunnel (2.0 (1.1-8.5)), lowest in the superior vena cava (0.8 (0.5-2.4)), and intermediate in the left and right pulmonary arteries (1.6 (0.9-2.0) and 1.2 (0.4-1.9), respectively). Flow and pressure waveforms were biphasic with maxima in atrial systole and late ventricular systole. CONCLUSIONS: Following a standard lateral tunnel TCPC, flow returning via the superior vena cava is not lower than flow returning via the inferior vena cava as otherwise seen in healthy subjects; flow distribution to the pulmonary arteries is optimal; and some pulsatility is preserved primarily in the lateral tunnel and the corresponding pulmonary artery. This study provides in vivo data for future in vitro and computer model studies.

Perioperative metoprolol reduces the frequency of atrial fibrillation after thoracotomy for lung resection.

OBJECTIVE: The association of atrial fibrillation with thoracic surgical procedures is well known, but nevertheless its cause is not well defined. Increased sympathetic activity may play a role in the development of atrial fibrillation, and reduced beta-receptor activity may be advantageous. The objective was to evaluate the effect of oral beta-blockade on the frequency of atrial fibrillation and to evaluate some possible causative factors. DESIGN AND SETTING: The study was prospective, randomized, and double-blind, and was conducted at Aarhus University Hospital. PARTICIPANTS: Thirty patients without previous or present cardiovascular history undergoing elective thoracotomy for lung resection. INTERVENTIONS: The patients received either 100 mg of metoprolol or placebo orally before surgery and once daily postoperatively. Anesthesia consisted of a thoracic epidural block combined with general intravenous anesthesia. Epidural morphine was continued postoperatively. MEASUREMENTS AND MAIN RESULTS: Patients were monitored with electrocardiograms (ECGs), capillary pulse oximetry, invasive hemodynamic monitoring, central venous oxygen saturation, arterial blood gases, serum electrolytes, and fluid balances. Atrial fibrillation developed in 23.3% of the patients, 6.7% after metoprolol compared with 40% in the placebo group. Atrial fibrillation developed a mean of 2.9 days postoperatively. The predominant hemodynamic findings were perioperative lower oxygen consumption and postoperative lower cardiac index after metoprolol. Patients developing atrial fibrillation had much higher oxygen consumption and postoperative cardiac index than other patients. CONCLUSION: Perioperative oral beta-blockade can reduce the frequency of atrial fibrillation without serious side effects. Increased sympathetic activity is one of the predominant factors in the cause of this complication.

Preoperative metoprolol improves cardiovascular stability and reduces oxygen consumption after thoracotomy.

BACKGROUND: Increased sympathetic activity perioperatively and associated cardiovascular effects play a central role in cardiovascular complications. High thoracic epidural blockade attenuates the sympathetic response, but even with complete pain relief, haemodynamic and endocrine responses are still present. Beta-adrenoceptor blockade is effective in situations with increased sympathetic activity. This study was designed to evaluate the perioperative haemodynamic effect of preoperative beta-blockade and its influence on the haemodynamic aspects of the surgical stress response. METHODS: Thirty-six otherwise healthy patients undergoing elective thoracotomy for lung resection were randomised double-blinded to receive either 100 mg metoprolol or placebo preoperatively. Anaesthesia was combined high thoracic epidural block and general anaesthesia. The epidural analgesia was continued during recovery. Patients were monitored with ECG, pulse oximetry, invasive haemodynamic monitoring, arterial blood gases and electrolytes. RESULTS: After induction of anaesthesia the mean arterial pressure (MAP) decreased in both groups, and decreased further in the placebo group after initiation of the epidural block. The heart rate (HR) was slightly less throughout the observation period after metoprolol. Peroperatively, the only difference in measured haemodynamics was a marginally higher MAP after metoprolol. Postoperative cardiac index (CI) was lower with a lower variability and cardiac filling pressures were slightly higher in the metoprolol group. The oxygen consumption index was higher after placebo throughout the observation period, with no difference in the oxygen delivery. CONCLUSION: We found that preoperative beta-blockade during combined general anaesthesia and high thoracic epidural blockade stabilised perioperative HR and CI and decreased total oxygen consumption.

[Ketamine. A controversial anesthetic agent]. / Ketamin. Et kontroversielt anaestesimiddel.

On the basis of a review of the literature, a survey is presented concerning the controversial anaesthetic agent ketamine, its pharmacology, mechanism of action and employment. Particular emphasis is placed on the cerebral, cardiovascular and pulmonary effects and the clinical employment. Similarly, the side effects and their prophylaxis are described. It is concluded that ketamine is considered to be a valuable preparation which can be employed both in and outside hospital.

Respiratory depression following postoperative analgesia with epidural morphine.

Eighteen healthy patients subjected to operation for duodenal ulcer were allocated randomly to one of two regimes of analgesic treatment with epidural morphine. The analgesic regime was started either per- or postoperatively. Epidural morphine in doses of 4 mg was given until satisfactory pain relief was achieved. PaCO2 and respiratory rate were measured hourly for 10 h and a nearly identical respiratory depression was found in the two groups. Peak PaCO2-values were seen in the 5th and 6th postoperative hour. The respiratory rate was initially high and declined during the first postoperative hours. Only one patient in each group had a pathologically low respiratory rate (8 min-1), but this was transient and seen in the 10th postoperative hour. The needs for epidural morphine on the first postoperative day were highest in the peroperative group. It is concluded that a peroperative start of pain treatment with epidural morphine does not affect the degree of respiratory depression or reduce the postoperative analgesic requirements.

Gastric volume and pH in children for emergency surgery.

The volume and pH of gastric contents aspirated prior to anaesthesia were measured in 101 children admitted for emergency surgery. The children were aged between 3 months and 15 years. If we define potential patients at risk by means of the volume and pH of the gastric contents, then 50.0% of the children were at risk of aspiration into the lungs. The number of patients at risk was higher in children aged between 6 and 10 years. There was almost the same risk in the groups with abdominal-, urogenital-, and orthopaedic diseases, while the number of patients at risk was less in the group with superficial lesions. The length of fasting time in the child considerably influenced the volume of gastric contents in emergency surgical cases. It is concluded that in children admitted for emergency surgery there is a risk of aspiration of gastric contents into the lungs. The risk is reduced by preanaesthetic fasting. All children admitted for emergency surgery must be carefully evaluated prior to anaesthesia with special reference to gastric aspiration.

Profound accidental hypothermia treated with peritoneal dialysis.

In five women and two men, profound accidental hypothermia--core temperature on admission 24-28 degrees C--was treated with peritoneal dialysis. In two cases 16 gauge intravenous catheters were used, without difficulty, for the dialysis. Six of the seven patients were intoxicated by hypnotics, and four also by alcohol. Two patients died--one 38 hours after admission due to acute myoglobinuric renal failure arising from gangrene of an arm, and the other after 71 hours, due to cerebral herniation. The remaining five patients recovered without cerebral sequelae. Peritoneal dialysis is a useful procedure for rewarming patients with profound accidental hypothermia.

Urinary retention during i.m. and extradural morphine analgesia.

In the postoperative period fifty-six healthy patients undergoing cholecystectomy or operations for duodenal ulcer, received, in a randomized order, i.m., "high-level" or "low-level" extradural morphine. Thirty-five per cent in the i.m. group, 33% in the high-level group and 50% in the low-level group suffered urinary retention, in all cases within the first 24 h. The mean cumulative dose of morphine necessary for pain relief was in the same range (13.4-16.5 mg) during the first 2 h of therapy for all groups, while the amounts after 24 and 48 h were twice to four times with the i.m. route compared with the extradural route. A peripheral effect of morphine on the urinary bladder is possible and the mechanism of action is discussed.

Postoperative analgesia and lung function: a comparison of intramuscular with epidural morphine.

Thirty healthy patients subjected to cholecystectomy or operation for duodenal ulcer were allocated randomly for postoperative analgesic treatment with morphine i.m. or epidurally. Morphine was given only at the request of the patients and only as much was given as was needed to obtain satisfactory pain relief. Patients in the epidural group were given morphine exclusively by epidural injection. In the epidural group a lower incidence of radiological changes in the lungs was found postoperatively - 21% as against 67%. Compared with the i.m. group, there was a higher arterial oxygen tension and a slower increase in alveolar-arterial oxygen difference. It is concluded that epidural morphine analgesia reduces the degree of postoperative lung dysfunction compared with conventional i.m. morphine treatment.