Anaesthesia
-
Randomized Controlled Trial Clinical Trial
Evaluation of a needle-free injection system for local anaesthesia prior to venous cannulation.
We evaluated a single-use, disposable, carbon-dioxide-powered, needleless injector (J-Tip, National Medical Products Inc., CA, USA), which is claimed to deliver a virtually painless, subcutaneous injection. Seventy-two patients undergoing various types of surgery had a large-bore intravenous cannula inserted prior to induction of general anaesthesia. Three minutes beforehand, a subcutaneous injection of 0.3 ml of 1% plain lidocaine was administered. ⋯ Pain scores were recorded on injection of the lidocaine and on insertion of the cannula. There was significantly less pain on injection with the needleless injector than with the 25 G needle (p < 0.001) but, surprisingly, there was more pain on cannulation (p < 0. 001). We conclude that the device certainly delivers a less painful subcutaneous injection than a 25 G needle, but perhaps provides less effective skin anaesthesia for venous cannulation at sites where the subcutaneous space is small; its use might be better suited to areas where the subcutaneous space is deeper.
-
Randomized Controlled Trial Clinical Trial
Airway obstruction with cricoid pressure.
Cricoid pressure may cause airway obstruction. We investigated whether this is related to the force applied and to the technique of application. We recorded expired tidal volumes and inflation pressures during ventilation via a face-mask and oral airway in 52 female patients who were anaesthetised and about to undergo elective surgery. ⋯ An expired tidal volume of < 200 ml was taken to indicate airway obstruction. Airway obstruction did not occur without cricoid pressure, but did occur in one patient (2%) with cricoid pressure at 30 N, in 29 patients (56%) with 30 N applied in an upward and backward direction and in 18 (35%) patients with cricoid pressure at 44 N. Cricoid pressure applied with a force of 44 N can cause airway obstruction but if cricoid pressure is applied with a force of 30 N, airway obstruction occurs less frequently (p = 0.0001) unless the force is applied in an upward and backward direction.
-
Randomized Controlled Trial Comparative Study Clinical Trial
Bispectral index monitoring: comparison of two types of electrode.
Bis-monitoring is a new method of monitoring anaesthetic depth. Bis-monitoring is easy to perform, but the Bis-monitor and the original, disposable electrodes are expensive. The aim of this study was to determine whether the original Zipprep electrodes could be replaced by the much cheaper electrocardiogram electrodes. ⋯ The impedance in the electrocardiogram electrodes was higher than in the Zipprep electrodes, but this did not affect the bispectral index. No other problems with either type of electrode were detected. It is concluded that Zipprep electrodes can be replaced by electrocardiogram electrodes in normal clinical practice.
-
Cricoid pressure is used to protect the lungs from contamination with gastric contents during tracheal intubation. We studied the effect of cricoid pressure applied with a yoke on 30 anaesthetised patients examined fibreoptically through a laryngeal mask airway. We assessed the effect of 20, 30 and 44 N on the internal appearance of the cricoid and vocal cords. ⋯ Associated difficulty in ventilation was present in 15 patients (50%) and 18/30 (60%) had vocal cord closure with associated difficult ventilation, at forces up to 44 N. Cricoid occlusion was unrelated to age and body mass index but females were at greater risk. Orthodox values of cricoid pressure, applied with a yoke, may produce obstruction at the level of the cricoid cartilage or vocal cords, with implications for tracheal intubation and ventilation by mask.
-
We performed an in vitro study to determine the thermal safety of a domestic microwave to warm intravenous crystalloid solutions. Five-hundred-millilitre bags of crystalloid, randomly allocated to groups which differed in power setting, timer setting and whether or not agitation was performed after warming, were heated in a microwave oven to a calculated temperature of 39 degrees C. Timer accuracy was checked by stopwatch. ⋯ There were significant differences between the in-line temperatures of shaken and unshaken bags at each power setting, but not when groups were added together. There was no change in colour or odour of bags or fluid. One bag developed a pinhole leak when the packaging was removed.