Feng-Sheng Lin

Effect of combining dexmedetomidine and morphine for intravenous patient-controlled analgesia

BACKGROUND Perioperative use of dexmedetomidine is associated with reduction in postoperative analgesic requirements. This study examined whether dexmedetomidine added to i.v. patient-controlled analgesia (PCA) morphine could improve analgesia while reducing opioid-related side-effects. METHODS In this double-blinded, randomized, controlled study, 100 women undergoing abdominal total hysterectomy were allocated to receive either morphine 1 mg ml(-1) alone (Group M) or morphine 1 mg ml(-1) plus dexmedetomidine 5 microg ml(-1) (Group D) for postoperative i.v. PCA, which was programmed to deliver 1 ml per demand with a 5 min lockout interval and no background infusion. Cumulative PCA requirements, pain intensities, cardiovascular and respiratory variables, and PCA-related adverse events were recorded for 24 h after operation. RESULTS Compared with Group M, patients in Group D required 29% less morphine during the 0-24 h postoperative period and reported significantly lower pain levels from the second postoperative hour onwards and throughout the study. Whereas levels of sedation were similar between the groups at each observational time point, decreases in heart rate and mean blood pressure from presurgery baseline at 1, 2, and 4 h after operation were significantly greater in Group D (by a range of 5-7 beats min(-1) and 10-13%, respectively). The 4-24 h incidence of nausea was significantly lower in Group D (34% vs 56.3%, P<0.05). There was no bradycardia, hypotension, oversedation, or respiratory depression. CONCLUSIONS The addition of dexmedetomidine to i.v. PCA morphine resulted in superior analgesia, significant morphine sparing, less morphine-induced nausea, and was devoid of additional sedation and untoward haemodynamic changes.

Combination of opioid agonist and agonist–antagonist: patient-controlled analgesia requirement and adverse events among different-ratio morphine and nalbuphine admixtures for postoperative pain

BACKGROUND Nalbuphine, a mixed agonist-antagonist opioid, has a potential to attenuate the mu-opioid effects and to enhance the kappa-opioid effects. However, when morphine and nalbuphine are mixed together, the clinical interactions in different combining ratios on analgesic effect and adverse events are unknown. METHODS This randomized, double-blind controlled study investigated five different combining ratios of morphine and nalbuphine in 311 patients undergoing gynaecologic operations. The concentrations [morphine (mg ml(-1))]/[nalbuphine (mg ml(-1))] were 1/0 in Group 1, 0.75/0.25 (ratio 1:3) in Group 2, 0.5/0.5 (ratio 1:1) in Group 3, 0.25/0.75 (ratio 3:1) in Group 4, and 0/1 in Group 5. Patient-controlled analgesia (PCA) requirement, postoperative pain, and adverse events were evaluated throughout the postoperative 24 h period. RESULTS Twenty-four hour PCA requirements were similar among the five groups. Verbal rating scores for pain were statistically higher in Groups 2 and 4 than in Group 3. The incidences of pruritus were higher in Group 1 (15.6%) than in Group 2 (6.2%), Group 3 (3.4%), Group 4 (1.6%), and Group 5 (0%). The incidences and severity of dizziness, nausea, and vomiting were not significantly different. CONCLUSIONS The interaction between morphine and nalbuphine in PCA admixture on analgesia is additive. Combinations of morphine and nalbuphine in PCA can decrease the incidence of pruritus, and the antipruritus effect is ratio-dependent. This may provide a novel combination strategy of opioid agonist and agonist-antagonist for postoperative pain management after gynaecologic surgery.

Compatibility and stability of binary mixtures of ketorolac tromethamine and tramadol hydrochloride injection concentrate and diluted infusion solution.

OBJECTIVE Ketorolac added to tramadol as an injection mixture convenient for clinical use has been shown to be an effective balanced analgesic regimen in alleviating moderate-to-severe pain. However, analytical confirmation of the compatibility and stability of this combination is not available. This study examined the compatibility and stability of this combination. METHODS Two different mixtures containing ketorolac tromethamine and tramadol hydrochloride were examined: ketorolac (10 mg/mL) and tramadol (33.3 mg/mL) prepared as injection concentrate in ampoule mingled together in the ratio of one ampoule to one ampoule; diluted ketorolac (2 mg/mL) and tramadol (20 mg/mL) prepared in saline infusion solution, with or without pH adjustment. The mixtures were visually inspected for precipitation and color change. Quantitative chemical analysis was performed on days 0, 1, 3 and 7 by high-performance liquid chromatography. RESULTS When stored at room temperature under ambient light, the ketorolac (10 mg/mL)-tramadol (33.3 mg/mL) injection concentrate and ketorolac (2 mg/mL)-tramadol (20 mg/mL) solution, without pH adjustment and adjusted to pH 5-8, were physico-chemically stable, and neither visible precipitation nor loss of concentration was found. With the ketorolac (2 mg/mL)-tramadol (20 mg/mL) solution adjusted to pH 9, however, precipitation occurred immediately, resulting in a significant loss of tramadol. CONCLUSION This study suggests that a ready-to-use ketorolac-tramadol mixture, either undiluted or diluted in physiological saline solution, can be prepared, with a shelf life of at least 7 days when stored at room temperature under ambient light.

Nitrous oxide suppresses tonic and phasic nociceptive behaviors but not formalin-induced c-Fos expression in the rat spinal cord dorsal horn.

BACKGROUND The aim of this study was to investigate the anesthetic and analgesic effects of subanesthetic concentration of nitrous oxide and to compare these effects with halothane and fentanyl. METHODS The antinociceptive effects were assessed in male Sprague-Dawley rats by behavioral responses to phasic and tonic nociceptive stimulations and biochemical index of pain, formalin-induced Fos-like immunoreactivity (Fos-LI), in spinal cord dorsal horn. Neurological functions (proprioception, mental status and motor function) were monitored to determine whether or not behavioral responses were impaired by anesthetic action of the treatment. Four groups of rats treated with: (1) saline, (2) 75% nitrous oxide (0.5 MAC), (3) 0.5% halothane (0.5 MAC) and (4) fentanyl 100 micrograms/kg were subject either to graded intensity of CO2 laser stimulation (phasic pain) or s.c. injection of 50 microliters 2.5% formalin (tonic pain) in two separate studies. All rats in the tonic pain study were killed for immunohistochemistry at 60 min after formalin injection. Maximal counts of Fos-LI labelled neurons in rat spinal cord dorsal horn were compared according to the laminar distribution. RESULTS We found that all rats exhibited normal righting reflexes regardless of whatever treatment. Nitrous oxide and halothane greatly impaired mental status and motor function, indicating that both agents could induce a modest degree of sedation and paresis at subanesthetic concentrations. Fentanyl increased the threshold level to noxious thermal stimulation, and reduced the formalin-induced licking/biting behaviors and the number of Fos-LI labelled neurons which are predominantly found in the neck of the dorsal horn. Nitrous oxide and halothane increased the thermal nociceptive threshold, suppressed licking/biting behavior in both early and late phases of the formalin test. Unlike fentanyl, nitrous oxide and halothane failed to suppress c-fos expression. The extent and pattern of nitrous oxide-induced antinociception was identical to halothane, which is known to have little or no analgesic effect. The lack of attenuated biochemical response to tonic pain stimulation may suggest that nitrous oxide fails to suppress spinal sensitization despite its potent inhibition on behavioral hyperalgesia. CONCLUSIONS These findings suggest that, at the spinal level, subanesthetic concentration of nitrous oxide greatly attenuates nociceptive behaviors mainly due to a non-selective suppression of behavioral responses that are commonly associated with inhalation anesthetic drugs.

The role of transesophageal echocardiography in transplantation of an adult-sized kidney to a small child

Transplantation of adult-sized kidneys to pediatric patients weighing less than 10 kg is a challenge to both surgical and anesthetic management. For survival of the graft, a large-size kidney graft transferred to a pediatric patient needs extraphysiological cardiac output to compensate for adequate renal blood flow. We report here a boy weighing 8.4 kg who received transplantation of a kidney donated by his 56.4-kg mother. Since monitoring of the central venous pressure was not accurate enough and Swan-Ganz catheterization was not feasible in this patient for monitoring the fluid status and cardiac function, we used transesophageal echocardiography to guide intravascular volume expansion and to titrate inotropic support during the surgery. It was demonstrated to be a useful tool for optimization of renal perfusion in this scenario. The transplanted graft served its function well.

Compatibility and stability of ketorolac tromethamine and morphine hydrochloride in 0.9% sodium chloride injection

Abstract Introduction: Ketorolac added to morphine solution as a convenient regimen for pain management is common in clinical practice in many centers. However, the analytical confirmation of the compatibility and stability of this combination has rarely been performed. This study examined the compatibility and stability of ketorolac tromethamine and morphine hydrochloride combined in 0.9% sodium chloride injection. Materials and methods: Ketorolac tromethamine and morphine hydrochloride were mixed together in 0.9% sodium chloride injection at pH 5–9 at a final concentration of 2 mg/ml for ketorolac and 1 mg/ml for morphine. In addition, 20 different ketorolac–morphine mixture solutions were prepared by combing various concentrations of each individual drug. The compatibility and stability of these solutions were studied using high performance liquid chromatography. Results: There was no significant loss of drug, neither ketorolac tromethamine nor morphine hydrochloride, with the ketorolac (2 mg/ml) + mor...

Evident cognitive impairments in seemingly recovered patients after midazolam-based light sedation during diagnostic endoscopy

BACKGROUND/PURPOSE Midazolam is a widely used sedative agent during colonoscopy, with cognitive toxicity. However, the potential cognitive hazard of midazolam-based light sedation has not been sufficiently examined. We aimed to examine the cognitive safety and vulnerability profile under midazolam light sedation, with a particular focus on individual variations. METHODS We conducted a prospective case-controlled study in an academic hospital. In total, 30 patients undergoing sedative colonoscopy as part of a health check-up were recruited. Neuropsychological testing on the full cognitive spectrum was evaluated at 15 minutes and 120 minutes after low-dose midazolam administration. The modified reliable change index (RCI) was used for intrapersonal comparisons and controlling for practice effects. RESULTS Midazolam affected psychomotor speed (48%), memory (40%), learning (32%), working memory (17%), and sustained attention (11%), while sparing orientation and the fluency aspect of executive function at the acute stage. Residual memory (10%) and learning (10%) impairments at 2 hours after administration were evidenced in some patients. The three object recall and digit symbol coding tests can serve as useful screening tools. CONCLUSION Midazolam-based light sedation induced selective cognitive impairments and prolonged cognitive impairments occurred in patients with advanced age. A longer observation time and further screening were recommended for patients due to their at risk state.

Modified lightwand intubation in a child with spondyloepiphyseal dysplasia congenita.

This is the case report on a 1-year 9-month-old boy suffering from spondyloepiphyseal dysplasia congenita who was successfully intubated with our modified lightwand intubation procedure for general anesthesia to undergo bilateral herniorrhaphy despite the great likelihood of facing a difficult airway because of unstable cervical spine. We bent the pediatric wand after it was encased in an endotracheal (ET) tube of appropriate diameter. The light tip of the wand was let to protrude just out of the bevel of the ET tube. Once the light bulb properly transilluminated the trachea, the ET tube was threaded gently into the trachea. The patient recovered from anesthesia smoothly and was discharged on the next day. This maneuver can facilitate both visual and tactile confirmations of the position and proper tube size. The effectiveness and safety of our modified lightwand intubation procedure is well demonstrated.

Intravenous electrocardiography helps inexperienced operators to place totally implantable venous access device more accurately

Proper tip position is a major determinant of totally implantable venous access device (TIVAD) outcome. The aim of this study is to analyze the potential utilization of intravenous electrocardiography (IV‐ECG) to help inexperienced operators for TIVAD placement.