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Biomedical subjects

D B Carr

Publications and source records attributed to D B Carr.

At least 73 records · Page 4Linked to original sources

Cost considerations in patient-controlled analgesia.

Patient-controlled analgesia (PCA) is the use of a portable infusion pump activated by the patient to inject an analgesic drug intravenously, subcutaneously or epidurally. PCA permits a patient to deliver a small bolus of opioid to achieve prompt relief without over sedation. Use of PCA for pain management is increasing in hospitals and home settings, largely because it can provide equivalent or better analgesia than conventional methods, and patients are more satisfied with its use. This article reports on studies published between January 1984 and December 1995 which considered cost aspects of PCA. Most studies compared the direct costs of administering PCA with the cost of other forms of drug delivery, usually intramuscular injections. A few studies have included indirect costs such as length of stay and adverse effects associated with the use of PCA. The research on cost considerations of PCA is dominated by case reports, descriptive studies and poorly designed quasi-experimental studies. The most complete and well conducted studies usually have included only drug, equipment and labour costs. Only 6 randomised controlled trials were reported, all of which were conducted on postoperative patients. The cost effectiveness of PCA for pain management is an unresolved question because of the variability in methods used to determine costs and expenses, the different settings and patient populations in which PCA is applied, the different means to organise its management and the fact that it is a rapidly evolving technology during an era of changing reimbursement practices. There is substantial variation in the cost of drugs used in PCA and in the devices themselves, which influences the comparison of costs across studies. Also, researchers do not include the full scope of costs associated with the use of PCA in comparison with conventional drug delivery methods and some do not measure the level of pain relief achieved. Of the few complete and well designed published studies found, PCA was reported to produce superior analgesia at a higher cost than conventional intramuscular therapy in 3 studies, but to be more costly and produce less pain relief than intramuscular therapy in 1 study. There is a pressing need for cost-effectiveness, cost-utility and cost-benefit analyses to determine the appropriate clinical and cost circumstances for the use of PCA.

Analgesia, Patient-Controlled↗

Hippocampal afferents to the rat prefrontal cortex: synaptic targets and relation to dopamine terminals.

Afferents to the prefrontal cortex (PFC) from the hippocampal formation and from midbrain dopamine (DA) neurons have been implicated in the cognitive and adaptive functions of this cortical region. In the present study, we investigated the ultrastructure and synaptic targets of hippocampal terminals, as well as their relation to DA terminals within the PFC of adult rats. Hippocampal afferents were labeled either by anterograde transport of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) from the ventral hippocampal formation or by anterograde degeneration following fimbria lesion. Hippocampal terminals in the PFC, identified by either method, formed primarily asymmetric axospinous synapses, with a small percentage forming asymmetric axodendritic synapses. Dopamine terminals in the PFC were identified by peroxidase immunocytochemistry for either tyrosine hydroxylase or DA and formed primarily symmetric synapses onto dendritic spines and small caliber dendritic shafts. Spines that received symmetric synaptic contact from DA terminals invariably also received an asymmetric synapse from an unlabeled terminal, forming a triadic complex. Hippocampal and DA terminals in the PFC were not often observed in the same area of the neuropil, and no examples of convergence of hippocampal and DA terminals onto common postsynaptic targets were observed. Further analysis revealed that spines receiving synaptic contact from hippocampal terminals did not receive additional synaptic contact from any other source. However, when localized to the same area of the neuropil, hippocampal and DA terminals were often in direct apposition to one another, without forming axo-axonic synapses. These results suggest that 1) hippocampal terminals primarily form excitatory synapses onto spiny pyramidal neurons, 2) hippocampal afferents are unlikely to be synaptically modulated by DA or non-DA terminals at the level of the dendritic spine, and 3) appositions between hippocampal and DA terminals may facilitate presynaptic interactions between these afferents to the PFC.

Afferent Pathways↗

Incidence of nausea and vomiting in outpatients undergoing general anesthesia in relation to selection of intraoperative opioid.

STUDY OBJECTIVE: To measure the incidence of nausea and vomiting in outpatients in relation to selection of, or withholding of, intraoperative opioid. DESIGN: Prospective, randomized, double-blind control trial. SETTING: University general hospital. PATIENTS: 200 unpremedicated ASA status 1 and 11 patients, 8 to 80 years old, undergoing general anesthesia for ambulatory surgery. INTERVENTION: Patients were randomized to four groups, three of which received equipotent doses of different opioids intravenously (i.v.) during induction of anesthesia. Group 1 received nalbuphine 0.25 mg/kg, Group 2, alfentanil 20 ug/kg; Group 3, fentanyl 2 ug/kg; and Group 4, normal saline. MEASUREMENTS AND MAIN RESULTS: We evaluated (1) incidence and severity of nausea and vomiting in the postanesthesia care unit (PACU) and over the next 24 hours; (2) time to PACU discharge; (3) need for antiemetic therapy; and (4) need for analgesic rescue in the PACU. The incidences of nausea and vomiting were similar in all groups, as were time to discharge, antiemetic, and nonsteroidal antiinflammatory drug requirements. The highest incidences of nausea and vomiting occurred at 6 hours in all groups (23% and 9.5%, respectively). Group 1 required lower rescue doses of morphine in the PACU but this result may have been an artifact due to employing the mixed agonist-antagonist opioid, nalbuphine, in this group. CONCLUSIONS: Opioid administration at the doses employed during induction of anesthesia does not promote postoperative nausea or vomiting, nor increase length of stay in the PACU.

Adolescent↗

Equivalent outcomes during postoperative patient-controlled intravenous analgesia with lidocaine plus morphine versus morphine alone.

To evaluate a possible opioid-sparing effect of intravenous lidocaine we conducted a randomized, double-blind clinical trial. Patients undergoing intraabdominal surgery under general anesthesia were treated with patient-controlled analgesia (PCA) in three groups: Group 1 (n = 100; morphine 1 mg/mL), Group 2 (n = 44; morphine 1 mg/mL plus lidocaine 10 mg/mL), and Group 3 (n = 51; morphine 1 mg/mL plus lidocaine 20 mg/mL). Pain was evaluated using a 0-10 visual analog scale in the postanesthesia care unit (PACU) during deep inhalation at 15 and 30 min, and at 1, 2, and 4 h after arrival in the PACU, and continued after PACU discharge every 4 h for 36 h. Patients whose pain was more than 4/10 in the PACU received 2.5 mliters of the respective solutions every 7 min until pain was less than 4/10; then PCA was started. The number of bolus and cumulative drug doses during the study were recorded. Along with pain intensity, we assessed vital signs and side effects. Time to acceptance of oral liquids was also determined. Adding lidocaine 10 or 20 mg/mL to PCA morphine 1 mg/mL for acute pain treatment after abdominal surgery yielded no differences in opioid use, pain levels, or side effects.

Adolescent↗

Neurolytic celiac plexus block for treatment of cancer pain: a meta-analysis.

We performed a meta-analysis of the efficacy and safety of neurolytic celiac plexus block (NCPB) for cancer pain. A literature search yielded 59 papers, but data on NCPB in two or more patients was available in only 24 papers. Twenty-one studies were retrospective, one was prospective, and two were randomized and controlled. Cancer type was stated in 1117 of 1145 patients reported (63% pancreatic, 37% nonpancreatic). A bilateral posterior approach with 15-50 mL [corrected] of 50%-100% alcohol was the most common technique. Nonradiologically guided NCPB was performed in 246 patients (32%); guidance was by computed tomography (CT) in 214 (28%), radiograph in 271 (34%), fluoroscopy in 36 (5%), or ultrasound in 7 (< 1%). Good to excellent pain relief was reported in 878/989 patients (89%) during the first 2 wk after NCPB. Long-term followup beyond 3 mo revealed persistent benefit. Partial to complete pain relief continued in approximately 90% of patients alive at 3 mo post-NCPB and in 70%-90% until death even if beyond 3 mo post-NCPB. Patients with pancreatic cancer responded similarly to those with other intraabdominal malignancies. Common adverse effects were transient, including local pain (96%), diarrhea (44%), and hypotension (38%); complications occurred in 2%. This analysis suggests that: 1) NCPB has long-lasting benefit for 70%-90% of patients with pancreatic and other intraabdominal cancers, regardless of the technique used; 2) adverse effects are common but transient and mild; and 3) severe adverse effects are uncommon.

Celiac Plexus↗

Comparative analgesic efficacy of patient-controlled analgesia with ketorolac versus morphine after elective intraabdominal operations.

We conducted a randomized, double-blind trial to compare analgesia and side effects produced by ketorolac and morphine during postoperative patient-controlled analgesia (PCA). Fifty-one patients (ASA classes I and II) undergoing elective intraabdominal procedures were assigned to one of two groups. When postoperative pain first increased to 4/10 (by visual analog scale [VAS]), patients were randomly assigned to one of two groups. Group 1 (n = 25) received up to two intravenous (IV) boluses of 5 mg of morphine followed by IV morphine PCA, whereas those in Group 2 (n = 26) received up to two IV boluses of 30 mg ketorolac, then IV ketorolac PCA. Up to two rescue doses of morphine (5 mg per dose, subcutaneously) were given in either group when pain during deep inhalation exceeded 5/10 on VAS. Ten patients from Group 1 required rescue doses of morphine compared to 22 patients from Group 2 (P < 0.0011). Two and 16 patients from Groups 1 and 2, respectively, were withdrawn because of inadequate analgesia (P < 0.01). Mean pain scores were less in Group 1 than in Group 2 at each time, but only significantly so at 15 min (P < 0.0021), 30 min (P < 0.0336), and 24 h (P < 0.0358) after starting PCA. Time to acceptance of oral liquids was equivalent in Groups 1 and 2 (22 h and 21 h, respectively). IV ketorolac PCA, although well tolerated, has limited effectiveness as the sole postoperative analgesic after intraabdominal operations.

Abdomen↗

Spinal co-administration of peptide substance P antagonist increases antinociceptive effect of the opioid peptide biphalin.

Intrathecal injection of 0.25 micrograms of undecapeptide substance P antagonist (SPA) produced transient antinociception with a peak effect at 5 min. Increasing the SPA dose resulted in neurotoxicity. Intrathecal injection of the opioid peptide biphalin (BIP) produced antinociception for over 3 hrs without neurotoxicity. Co-administration of SPA (at subtoxic doses) increased BIP's antinociceptive effect. Naltrexone reversed analgesia due to BIP alone as well as after BIP+SPA.

Analgesics↗

Enhanced potency of intravenous, but not intrathecal, morphine and morphine-6-glucuronide after burn trauma.

We examined the analgesic effect of morphine (M) and its metabolite morphine-6-glucuronide (M6G) in a rat model of acute thermal trauma. M or M6G were given by intrathecal (IT) or intravenous (i.v.) routes after brief burn or sham burn delivered during inhalational anesthesia. In the sham group, M6G was significantly less potent than M when given i.v., yet tended to be more potent than M when given IT. For both drugs, thermal injury increased i.v. potency, yet decreased (for M) or displayed a trend to decrease (for M6G) It potency. The increased potency seen with i.v. but not IT opioid administration may reflect pharmacokinetic (e.g., diminished clearance) and/or pharmacodynamic responses (e.g., activation of peripheral opioid receptors) after thermal injury.

Analgesia↗

Morphine-3-glucuronide: silent regulator of morphine actions.

To assess whether stoichiometric manipulation of morphine (M) metabolism can enhance analgesia or slow the development of M tolerance we co-administered M-3- glucuronide (M3G) during single or repeated doses of morphine in rats. Although M3G itself lacked analgesic activity, co-injection of M3G with M increased and prolonged analgesia beyond that seen with M. In addition, diminution of the acute analgesic effect of M after 3 once-daily doses of M did not occur after daily co-injection of M3G and M. Thus the traditional view that tolerance to the effects of M is due solely to effects mediated through opioid receptors must be broadened to include the contributions of enzyme induction or stoichiometric equilibration of M3G in this process.

Analgesia↗

Infectious complications associated with temporary epidural catheters.

To identify cases of deep-tissue or local infection associated with temporary epidural catheters, we reviewed medical records from 1980 through 1992 and prospectively followed up patients with temporary epidural catheters from January 1993 through June 1993 who were hospitalized at a large, tertiary referral hospital. We identified seven cases of temporary epidural catheter-associated infection, including three cases of deep-tissue infection (paraspinal muscle abscess, epidural abscess, and meningitis) and four cases of local infection. The infections were diagnosed 2 days to 22 days following insertion of the epidural catheter. Staphylococcus aureus was isolated in four (57%) of the cases. All seven patients were treated with removal of the catheter and antimicrobial therapy; three patients also required surgical drainage for management of deep-tissue infection. Our findings emphasize the importance of daily inspection and prompt removal of temporary epidural catheters if infection is suspected.

Adult↗

Effects of ephedrine and phenylephrine on maternal and fetal atrial natriuretic peptide levels during elective cesarean section.

The effects of ephedrine and phenylephrine on fetal and maternal plasma atrial natriuretic peptide (ANP) concentrations were studied during 30 elective cesarean sections. After induction of spinal anesthesia, reductions from baseline maternal blood pressure were corrected with one of these pressor agents administered in a double-blinded, randomized manner. Immediately following delivery, umbilical artery (UA) ANP concentrations were significantly higher than umbilical vein (UV) concentrations (pg/ml) for both groups (ephedrine, 120.8 +/- 64.0 vs. 86.8 +/- 40.8, phenylephrine, 125.0 +/- 54.2 vs. 72.4 +/- 31.7), but there were no differences between groups for UA and UV ANP levels. Postpartum maternal ANP concentrations were significantly higher than baseline values in both groups, but again there were no differences between groups. Correlations between total doses of ephedrine or phenylephrine and UA or UV ANP levels did not reach significance. Postpartum maternal (MV2), UA, and UV blood gas variables (pH, PCO2, and PO2) were also not different between groups. These data suggest that effects of pressor doses of ephedrine (beta and alpha agonist) and phenylephrine (alpha agonist) on maternal and fetal ANP levels are not different. Therefore, 1) assuming these pressor drugs stimulate ANP release, this stimulation is not solely mediated by beta receptors and 2) to the extent that fetal ANP influences feto-placental circulatory homeostasis, the effects of ephedrine and phenylephrine on this regulatory mechanism do not appear to be different.

Adult↗