[Cardiovascular effects of a combination of vecuronium and low-dose fentanyl in atropinized and non-atropinized subjects]. / Effetti cardiovascolari dell'associazione tra vecuronio e basse dosi di fentanyl in soggetti atropinizzati e non-atropinizzati.

The cardiovascular effects of the pharmacologic association of low-dose fentanyl (2 micrograms/kg) and vecuronium (120 micrograms/kg) have been studied in 38 ASA I and II atropinized and non-atropinized patients scheduled for abdominal surgery during induction of anaesthesia with thiopentone or propofol. Whatever the induction agent used, heart rate was consistently reduced in patients not receiving an anticholinergic drug, while it was unchanged in patients treated with atropine intravenously. In non-atropinized patients impressively lower minimum heart rates were observed during induction of anaesthesia with thiopentone. In this last group one patient suffered from a cardiac arrest resolved without sequelae. In patients treated with the association between vecuronium and low doses of fentanyl a pretreatment with atropine is always indicated. Propofol seems to be a better induction agent than thiopentone.

[Comparison of 2 exchangers of heat and humidity in anesthesia (Hygrobac vs Ultipor BB50)]. / Confronto tra due scambiatori di calore ed umidità in anestesia (Hygrobac vs Ultipor BB50).

Comparison between Hygrobac and Ultipor BB50, two commercially available heat and moisture exchangers, shows that the former is more efficient: temperature (T degrees C) and water content (absolute humidity, AH) of the inspired gas is greater with Hygrobac than Ultipor BB50. However, both HMEs work at the low limit of the normally accepted range of T degrees C and AH for intubated patients.

[Cuff pressure in intratracheal tubes. Evaluation of the new Mallinckrodt-Brandt model]. / Pressione di cuffia nei tubi endotracheali. Valutazione del nuovo modello Mallinckrodt-Brandt.

Cuff pressure of endotracheal tubes increases to dangerous levels during anesthesia with nitrous oxide. In a small clinical study the Authors conclude that Mallinckrodt-Brandt endotracheal tubes are the only "low pressure" tubes available at the moment.

The induction phase of neuromuscular block after suxamethonium and pancuronium: analysis of the time constant of single-twitch decay (tau T1).

The T1% (first unconditioned stimulus of train-of-four) decay was analysed in 55 patients paralysed with different doses of suxamethonium and pancuronium during minor elective ear and nose surgery. In patients given pancuronium, T1% decay is well described by a mono-exponential function: a semi-log plot of ln(T1%) versus time is in fact a straight line. Predicted values are quite comparable with mean and individual values recorded in patients. From these equations the time-constant of single-twitch decay, or tau T1, may be calculated easily: it is a good dynamic descriptor of the speed of onset of neuromuscular block. In patients paralysed with suxamethonium, the rapidly developing block makes it difficult to acquire a sufficient number of data for computation of regression lines: while T1% seems to decrease exponentially, as in the pancuronium groups, no definite conclusions are possible at present. The authors conclude that tau T1 may be a useful dynamic descriptor of neuromuscular block induced by non-depolarizing muscular blocking drugs. Two new concepts are introduced: (i) the time spent to overcome the 'margin of safety' of neuromuscular transmission, or T MOS; and (ii) the speed index, as a measure of the relative speed of the onset of block.

Time constant of single-twitch decay during the induction phase of neuromuscular block: a clinical study with atracurium besylate.

Visual inspection of several records of the onset of neuromuscular block due to atracurium suggested that the temporal decay in the response to the first stimulus (T1) of train-of-four could be regarded as an exponential process, analogous to the distribution (alpha) phase of the drug. Retrospective analysis of 69 train-of-four tracings recorded in patients of both sexes scheduled for minor elective surgery confirmed that T1% decay is best described by an exponential function, theoretical values correlating well with the recorded values (r greater than 0.9, P less than 0.01).