Pain
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Processing of nociceptive information can be modulated at various levels in spinal cord that may range from changes of neurotransmitter release from primary afferent Adelta- or C-fibres to excitability changes of spinal interneurones or motoneurones. The site and mechanism of action of spinal analgesics has been assessed with a number of in vivo and in vitro methods with sometimes conflicting results. ⋯ Polysynaptic responses were dose-dependently inhibited while the monosynaptic response remained unaffected. These results suggest that spinal analgesics may preferentially affect polysynaptic but not monosynaptic Adelta-fibre-evoked responses in superficial spinal dorsal horn.
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Studies have shown that the steroid anaesthetic alphaxalone positively modulates gamma-aminobutyric acid (GABA) receptors in vitro. It has also been reported that positive modulation of GABA(A) receptors in the rat spinal cord can produce antinociception in vivo. This present study looks at the interaction of an intraperitoneal injection (i.p.) of the steroid anaesthetic combination Saffan (alphaxalone 9 mg/ml, alphadolone acetate 3 mg/ml) with GABA(A) receptors in the spinal cord. ⋯ Alphadolone caused no sedation but it did cause antinociceptive effects equal in magnitude to those produced by Saffan. We conclude that Saffan produces antinociception in rats when given i.p. by an interaction with spinal GABA(A) receptors. Furthermore, this antinociception is due to the alphadolone content of the neurosteroid anaesthetic and not the alphaxalone.
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Ovariohysterectomy in the rat led to the induction of abdominal postures and referred mechanical allodynia in the hind paws. The latter was differentiated into static and dynamic subtypes. The abdominal postures were present up to 4-5 h, whilst the two types of allodynia lasted for at least 2 days. ⋯ In contrast, administration of three doses of morphine (3 mg/kg) in a similar dosing regime but starting 24 h after surgery, only blocked the two types of allodynia for 4 h. These data indicate the importance of blocking the induction phase of surgical pain and support the concept of pre-emptive analgesia. It is suggested that the ovariohysterectomy model should prove to be useful for studying mechanisms and designing novel therapeutic strategies for the treatment of post-operative pain.
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Randomized Controlled Trial Clinical Trial
Intravenous morphine in postoperative infants: intermittent bolus dosing versus targeted continuous infusions.
Eighty-three infants received i.v. morphine following surgery as a continuous infusion to a targeted morphine concentration of 20 ng ml(-1) (n = 56) or as intermittent bolus doses as needed (n = 27). Ventilation was compared in the two groups by continuous pulse oximetry, by venous blood gases on postoperative day 1 (POD 1) and by CO2 response curves. Infant pain scores were done to assess analgesia every 4 h. ⋯ Morphine clearance increased with age. Infants with detectable morphine also had measurable morphine-6-glucuronide in both groups. Oral intake began at 16 h in both groups and other side effects were infrequent.
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Comparative Study
Barriers to the analgesic management of cancer pain: a comparison of attitudes of Taiwanese patients and their family caregivers.
The purposes of this study were as follows: (1) to compare the attitudes which were considered to be barriers to cancer pain management held by Taiwanese cancer patients and their family caregivers; (2) to determine if these barriers were related to patient hesitancy to take analgesics and/or family caregiver hesitancy to administer analgesics: and (3) to determine if attitudinal barriers by patients and/or family caregivers predicted the adequacy of analgesics that patients used. A total of 159 dyads of oncology outpatients and their primary family caregivers (n = 318) participated in this study. The instruments completed by patients consisted of the Barriers Questionnaire-Taiwan form, the Brief Pain Inventory-Chinese version, the ECOG performance status scale, and a demographic and medication questionnaire. ⋯ Patient concerns were related to their hesitancy to take analgesics and, similarly, caregiver concerns were related to their hesitancy to administer analgesics. Most importantly, patient and caregiver concerns had an impact on how the patients' pain was managed: (1) patients and their family caregivers with higher levels of concerns used inadequate analgesics as compared to patients using adequate analgesics; (2) family caregiver barriers (concerns) were a significant predictor of inadequate management of cancer pain (after controlling for demographic and disease variables). Therefore, educational interventions for overcoming these barriers for both patients and their family caregivers may have potential for improving the management of cancer pain in Taiwan.