Anesthesiology
-
Comparative Study
Intrathecal midazolam and fentanyl in the rat: evidence for different spinal antinociceptive effects.
The effects of intrathecal midazolam and fentanyl on electrical current threshold for pain were measured using stimulating electrodes in the neck and tail of rats with chronically implanted lumbar subarachnoid catheters. This involved the measurement of the minimum current (50 Hz 2 ms pulses 0-5 mA), which made the rat squeak when applied alternately to electrodes at each skin site. The responses measured in milliamperes were expressed as a number of times control readings. ⋯ Tail withdrawal in response to non-noxious stimulation was preserved in all animals with spinal analgesia, indicating that myelinated afferent and efferent pathways were still functioning. Righting reflex, coordination, motor power, and alertness were also preserved in the presence of both drugs. Both drugs caused spinally mediated antinociceptive effects that were qualitatively different.
-
Cerebral blood flow (CBF) responsiveness to alterations in arterial CO2 tensions (PaCO2) during 1.4% and 2.8% isoflurane anesthesia was assessed. Dogs were initially anesthetized with thiopental (12 mg/kg, iv bolus), their tracheae intubated, after which anesthesia was maintained with 1.4% isoflurane. In eight animals three levels of PaCO2 (25, 40, and 60 mmHg) were studied during 1.4% and 2.8% isoflurane. ⋯ In a second group of animals (n = 8), the effects of changes in CPP during hypercapnia with 1.4% and 2.8% isoflurane were assessed. Increasing CPP approximately 25 mmHg with both 1.4% and 2.8% isoflurane increased CBF but did not change CVR from control. With 1.4% isoflurane, the cerebral vasculature constricts with hypocapnia and dilates with hypercapnia, whereas with 2.8% isoflurane, vasoconstriction to hypocapnia is retained but vasodilation to hypercapnia is absent.(ABSTRACT TRUNCATED AT 250 WORDS)
-
Randomized Controlled Trial Comparative Study Clinical Trial
A comparison of morphine, meperidine, and oxymorphone as utilized in patient-controlled analgesia following cesarean delivery.
Seventy-five patients (n = 75) undergoing elective cesarean delivery during epidural anesthesia were randomly assigned to receive one of three opioid analgesics via patient-controlled analgesia (PCA) when they first complained of pain in the recovery room. Following administration of an analgesic loading dose, patients were allowed to self-administer morphine 1.8 mg, meperidine 18 mg, or oxymorphone 0.3 mg iv every 8 min as required. Data collected during the 24-h observation period included visual analog scale (VAS) pain scores at rest and during movement, VAS patient satisfaction scores, total drug administered, the ratio of attempts/injections, and the incidence of nausea/vomiting, sedation, and pruritus. ⋯ Oxymorphone was associated with the highest incidence of nausea and vomiting (P less than 0.05), whereas increased sedation and pruritus were noted with morphine. Patient satisfaction with drug effect demonstrated significant negative correlations with resting pain scores and degree of sedation. Whereas morphine is a more commonly utilized PCA analgesic, the excellent analgesia, low incidence of sedation, and high patient satisfaction provided by meperidine and oxymorphone suggested useful alternatives.