Anesthesia and analgesia
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Anesthesia and analgesia · Dec 2005
A single dose of intrathecal morphine in rats induces long-lasting hyperalgesia: the protective effect of prior administration of ketamine.
An active pronociceptive process involving N-methyl-D-aspartate (NMDA) receptor activation is initiated by opioid administration, leading to opioid-induced pain sensitivity. Experimental observations in rats have reported reduction of baseline nociceptive threshold after prolonged spinal opioid administration. In this study we sought to determine whether a single dose of intrathecal morphine can induce hyperalgesia in uninjured rats and to assess the effects of pretreatment with the NMDA-antagonist ketamine on nociceptive thresholds. ⋯ A single intrathecal injection of morphine led to a biphasic effect on nociception; early analgesia associated with an increase in the nociceptive threshold lasting 3-5 h was followed by delayed hyperalgesia associated with a decrease in the nociceptive threshold lasting 1-2 days. Subcutaneous ketamine did not significantly modify the early analgesic component but almost completely prevented the delayed decrease in nociceptive threshold after intrathecal administration of morphine. A single intrathecal injection of morphine in rats produces a delayed and sustained hyperalgesia linked to the development of opioid-induced pain sensitivity.
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Anesthesia and analgesia · Dec 2005
Randomized Controlled Trial Comparative StudyA prospective comparative study of two indirect methods for confirming the localization of an epidural catheter for postoperative analgesia.
We prospectively evaluated, in randomized order, 2 indirect methods of confirming the localization of an epidural catheter for postoperative analgesia in 218 surgical patients: epidural stimulation test (EST) and epidural pressure waveform analysis (EPWA). The epidural space was localized by using a loss of resistance technique. All catheters were inserted 5 cm into the epidural space and primed with 5 mL of 0.9% normal saline. ⋯ We suggest the inclusion of sensory response in the appropriate dermatome at a current <10 mA as a criterion for adequate epidural catheter localization for EST testing. EPWA sensitivity was significantly better with older patients: 94% for patients older than 80 yr compared with 63% for patients younger than 40, 73% for patients 40 to 60, and 85% for patients aged 60 to 80 yr (P = 0.03). We conclude that the two tests are comparable for confirming catheter placement.
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Anesthesia and analgesia · Dec 2005
The safety of patient-controlled analgesia by proxy in pediatric oncology patients.
Between February 1999 and December 2003, we studied the use of patient-controlled analgesia (PCA) to control pain in 1011 children and young adults with cancer, by evaluating 4972 24-h periods of PCA usage, 576 of which involved PCA by proxy. Selection of patients for PCA by proxy was based on younger age group, neuromuscular limitation, expectation of repeated painful procedures, and terminal disease. ⋯ In the PCA by proxy group two respiratory complications, two neurological complications and one mixed respiratory and neurological complication were observed [corrected] Reversal of opioid-related respiratory or neurological effects with naloxone was required in three instances, two in the standard PCA group and one in the PCA by proxy group. Recommendations to ensure continuing safety include careful patient selection, education of proxy users, appropriate documentation, and institutional guidelines.
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Anesthesia and analgesia · Dec 2005
An evaluation of a vibro-tactile display prototype for physiological monitoring.
Visual displays and auditory alarms are used to convey information on physiological variables in an operating room. However, the exponential growth in the number of physiological variables and the high probability of false alarms has amplified demands on the clinician's attention. We have extended existing tactile technology to improve situational awareness and produce a practical clinical advisory device. ⋯ Most users preferred the vibro-tactile alarm although the prototype caused some discomfort. Furthermore, a combined vibro-tactile and auditory alarm had reduced accuracy when compared with the vibro-tactile alarm alone. The vibro-tactile modality shows considerable promise for clinical practice but will require further clinical testing and refinement, especially with regard to user comfort.