Articles: anesthetics.
-
Randomized Controlled Trial Clinical Trial
Propofol: clinical strategies for preventing the pain of injection.
Eight modes of administration of propofol were assessed in order to minimise the pain of injection. An intravenous bolus injection in the antecubital fossa was the only approach that caused no pain. ⋯ Slowing the speed of injection caused the greatest discomfort. An indirect biochemical mechanism for the pain is proposed.
-
Alfentanil was administered, together with midazolam, as part of a total i.v. anaesthetic technique. The pharmacokinetics of alfentanil were determined in 10 female patients undergoing lower abdominal surgery. The dose regimen of alfentanil, based on simulation studies, consisted of a two-stage infusion following an initial bolus dose. ⋯ Neither lower abdominal surgery nor the simultaneous administration of midazolam seemed to affect the kinetics of alfentanil as compared with results from studies in healthy volunteers. The short half-life of alfentanil, resulting from a small volume of distribution, makes it suitable as part of a total i.v. technique. Consideration must be paid, however, to interindividual differences in the pharmacodynamic response and in plasma clearance.
-
Conventional clinical dosages of local anesthetics may not be sufficient to block conduction of all afferent impulses, which is important for an effective epidural sensory blockade. Further depression of the transmission of information can be accomplished by central modulating mechanisms, preventing sensory perception. Since there are interindividual differences in the quality of modulating mechanisms, standardized depression of impulse propagation by the local anesthetic is associated with a wide variation in the total depression of afferent impulses. ⋯ Patients with a low pain threshold require a more highly concentrated local anesthetic. The addition of opioids to the local anesthetic will permit the use of lower concentrations of the local anesthetic itself. Optimal use of diagnostic, prognostic, and therapeutic epidural blockades is possible only if the influence of modulating mechanisms is taken into account.
-
The postoperative analgesic effect of opiate premedication and local anaesthetic blocks was studied in 929 patients having orthopaedic surgery. The median time to first request for postoperative analgesia was less than 2 h when neither opiate premedication nor block was used; opiate premedication increased the time significantly to more than 5 h; local anaesthetic block produced a further significant increase to 8 h and opiate premedication used with local anaesthetic block extended the median time further to more than 9 h. ⋯ Age had no significant effect. Prolonging the time before more pain relief is required may be worthwhile for both patients and staff.