Canadian journal of anaesthesia = Journal canadien d'anesthésie
-
During the past decade, major advances have taken place with regard to intravenous infusion anaesthesia. New opioid analgesics, iv anaesthetics, and muscle relaxants have become available, which are characterized by a rapid onset of action, short duration of clinical effect, and favourable side effect profiles. Optimal administration of these drugs is often best achieved by continuous infusion, rather than a more traditional technique of intermittent bolus administration. ⋯ Pharmacokinetic principles guide rational selection of the iv anaesthetic drugs according to both procedure and patient-specific requirements. In addition, improvements in the new programmable syringe infusion pumps provide a degree of simplicity and accuracy in operation, which make iv infusion of one, two or three components of the anaesthetic state a simple and practical reality for most procedures. In this CME article, these issues will be reviewed according to the following outline: Historical considerations; Rationale for continuous infusion of iv anaesthetic drugs; Pharmacokinetic and pharmacodynamic considerations; Infusion schemes; New techniques, new indications; IV anaesthetic delivery systems; Pharmacoeconomic considerations; Conclusions.
-
A two-dimensional model of the factors relevant to difficult laryngoscopy was analysed mathematically to determine clinical implications and limitations. The model describes the space into which the "inevitable residual volume" of the tongue (that part remaining anterior to the blade at laryngoscopy) can be displaced to permit a view of the larynx. Four points are used: the tip of the upper incisors; a point on the anterior airway just above the larynx; the mid-point between the mandibular condyles and the internal mid-point of the symphysis. ⋯ An otherwise normal jaw with this configuration recedes markedly on opening. Further studies are required to validate the model. Accurate quantification of individual factors in difficult laryngoscopy may then be feasible.
-
In order to determine the prevalence of psychoactive substance use in three specialty groupings, 1,624 questionnaires were sent to physicians in medicine, surgery and anaesthesia; all had trained at the same academic institution. A response rate of 57.8% was achieved. Comparison of prevalence of impairment rates showed no differences between Surgery (14.4%), Medicine (19.9%) and Anaesthesia (16.8%). ⋯ Seventy-three used psychoactive drugs which were non-prescribed. Drug counselling programmes were judged inadequate by most. Use of alcohol and drugs by faculty members was reported by a number of respondents.
-
The cuff of the laryngeal mask airway (LMA) is highly permeable to nitrous oxide (N2O), and cuff pressure increases during N2O/O2 anaesthesia. The extent of these changes and their effect on LMA position have previously only been investigated for short procedures. The current study was designed to investigate the effects of nitrous oxide-oxygen (N2O/O2) anaesthesia lasting one to two hours on cuff pressure, LMA positioning and pharyngeal morbidity. ⋯ Three of 19 patients had a mild sore throat. This study demonstrates that the increase in LMA cuff pressure is self limiting over a one-to-two-hour period and does not cause displacement of the LMA. There is no evidence that cuff pressure monitoring and pressure limitation is necessary during LMA anaesthesia.
-
The authors evaluated the accuracy of an intrathecal test dose (TD) to rule out unintentional subarachnoid injection in a prospective and double-blind study. Twenty-nine unmedicated patients scheduled to receive continuous spinal analgesia for their surgical procedures entered the study. After placement of non-invasive monitoring (ECG, BP and SpO2), an intrathecal catheter was placed in the lumbar area. ⋯ At four minutes SN reached 100% (CI 78-100%) for R and H, while only R obtained a SP of 93% (CI 66-100%). Using R as detector of intrathecal injection the -PV was 100% and the +PV 25% (assuming a 2% prevalence of unintentional spinal). We conclude that, with our test dose; (a) four minutes are needed to recognize signs of intrathecal injection; (b) leg-raising is a reliable sign; and (c) inquiring about other signs may only decrease the diagnostic accuracy of this test.