Wen-Kuei Chang

Effect of Oral Clonidine Premedication on Perioperative Hemodynamic Response and Postoperative Analgesic Requirement for Patients Undergoing Laparoscopic Cholecystectomy

BACKGROUND To investigate the clinical efficacy of oral clonidine premedication in anesthesia and analgesia in patients undergoing laparoscopic cholecystectomy (LC). METHODS One hundred and ten patients, scheduled for elective laparoscopic cholecystectomy, were recruited for the prospective, randomized, single-blind, comparative study. They were randomly allotted to either of the placebo or clonidine group. Patients of the placebo group (n = 65) were premedicated with oral antacid (alugel hydroxide 300 mg), while those in the clonidine group (n = 45) were premedicated with oral clonidine 150 micrograms prior to anesthesia. The premedication was given 60 to 90 min before the anticipated time of induction of anesthesia. Normocapnia was maintained throughout the perioperative period. Mass spectrometer was used to assess the inspired and expiratory concentrations of isoflurane, the anesthetic used for maintenance of anesthesia. Postoperative pain intensity, sedation scores, adverse events, time to the first dose of postoperative analgesic and cumulative analgesic requirement in 24 hours were recorded. Data were expressed as mean +/- SD. RESULTS Patients in the clonidine group displayed greater hemodynamic stability perioperatively and the isoflurane requirement was also reduced (30% less). The postoperative analgesic requirement was less (1.5 +/- 1.3 vs. 2.2 +/- 1.3 dose, P < 0.05) and the time for the first dose of analgesic was prolonged (411 +/- 565 vs. 264 +/- 441 min) in comparison with the placebo group but no statistic difference was found. CONCLUSIONS Oral clonidine premedication helped to provide perioperative hemodynamic stability, spared the use of isoflurane and reduced the requirement of postoperative analgesia so as to smoother the way to recovery in patients undergoing LC.

Factors Affecting Patient-controlled Analgesia Requirements

BACKGROUND/PURPOSE Intravenous patient-controlled analgesia (IVPCA) is one of the most widely used postoperative analgesic methods. Many factors could affect the total analgesic consumption of IVPCA. This retrospective study investigated the relationship between patient characteristics and total morphine consumption during a 3-day course of postoperative IVPCA. METHODS Patients receiving surgery under general anesthesia with postoperative IVPCA for 3 days during the period between January 2002 and December 2003 were included. Patient data including age, sex, weight, height, body mass index (BMI), operation type and site were collected. Total morphine consumption was recorded at the end of the 3-day IVPCA course. Stepwise regression analyses were conducted to select factors significantly associated with morphine consumption. Stratified analyses were also conducted among different surgical, BMI and age subgroups. RESULTS A total of 1308 patients (646 men, 662 women) were included in the analysis. For all operations, weight, age, procedures involving malignant disease, and surgical sites were significantly associated with total morphine consumption. The R and adjusted R2 values of the selected model were 0.509 and 0.256, respectively. Weight was the only common factor among all stratified analyses (all p < 0.001). Age was negatively correlated with morphine consumption. Gender was not a significant factor except in lower abdominal operations. Height was not associated with total morphine consumption. BMI status was not significantly associated with components of the selected factors. CONCLUSION This study demonstrated that weight and surgical sites significantly influence total IVPCA requirements. The effect of surgical sites should be considered when evaluating the influence of demographic characteristics on IVPCA demand.

Minocycline and fluorocitrate suppress spinal nociceptive signaling in intrathecal IL‐1β–induced thermal hyperalgesic rats

We previously demonstrated that intrathecal IL‐1β caused thermal hyperalgesia in rats. This study was conducted to examine the effects and cellular mechanisms of glial inhibitors on IL‐1β–induced nociception in rats. The effects of minocycline (20 μg), fluorocitrate (1 nmol), and SB203580 (5 μg) on IL‐1β (100 ng) treatment in rats were measured by nociceptive behaviors, western blotting of p38 mitogen‐activated protein kinase (MAPK) and inducible nitric oxide synthase (iNOS) expression, cerebrospinal fluid nitric oxide (NO) levels, and immunohistochemical analyses. The results demonstrated that intrathecal IL‐1β activated microglia and astrocytes, but not neurons, in the dorsal horn of the lumbar spinal cord, as evidenced by morphological changes and increased immunoreactivity, phosphorylated p38 (P‐p38) MAPK, and iNOS expression; the activation of microglia and astrocytes peaked at 30 min and lasted for 6 h. The immunoreactivities of microglia and astrocytes were significantly increased at 30 min (6.6‐ and 2.7‐fold, respectively) and 6 h (3.3‐ and 4.0‐fold, respectively) following IL‐1β injection, as compared with saline controls at 30 min (all P < 0.01). IL‐1β induced P‐p38 MAPK and iNOS expression predominantly in microglia and less in astrocytes. Minocycline, fluorocitrate, or SB203580 pretreatment suppressed this IL‐1β–upregulated P‐p38 MAPK mainly in microglia and iNOS mainly in astrocytes; minocycline exhibited the most potent effect. Minocycline and fluorocitrate pretreatment abrogated IL‐1β–induced NO release and thermal hyperalgesia in rats. In conclusion, minocycline, fluorocitrate, and SB203580 effectively suppressed the IL‐1β–induced central sensitization and hyperalgesia in rats.

Effect on Pain Relief and Inflammatory Response Following Addition of Tenoxicam to Intravenous Patient-Controlled Morphine Analgesia: A Double-Blind, Randomized, Controlled Study in Patients Undergoing Spine Fusion Surgery

OBJECTIVE This study tested the hypothesis that adding tenoxicam (T) to intravenous patient-controlled analgesia (IV-PCA) with morphine (M) would improve postoperative pain relief and wound inflammatory responses compared with M alone after spine surgery. DESIGN Randomized, prospective, double-blind, controlled study. SUBJECTS Ninety-four patients eligible for elective spine surgery. SETTING Teaching hospital. METHODS Patients were randomized to one of three groups: the M group (PCA regimen with M), the TM group (PCA regimen with T and M), or the T+TM group (20 mg T administered 30 minutes before wound closure in addition to the TM regimen). The primary end point was the numeric rating scale score for pain intensity, and secondary end points pertaining to postoperative pain management included M consumption, PCA demand/delivery, use of rescue analgesics, adverse events, and levels of inflammatory mediators in wound drainages. RESULTS PCA demand was reduced in both the TM and T+TM groups compared with the M group (both P ≤ 0.001). The incidence of skin itching was significantly reduced in the T+TM group compared with the other groups (both P ≤ 0.05). PGE2 and interleukin-6 levels in wound drainages were reduced in the TM and T+TM groups compared with the M group (both P ≤ 0.001). CONCLUSIONS The combination of T and M for IV-PCA was not more efficacious than IV-PCA with M alone in reducing postoperative pain after spine surgery but reduced PCA demand and suppressed local inflammation at the surgical site. Administration of T before wound closure may ameliorate IV-PCA M-induced skin itching.

Instructor-based Real-time Multimedia Medical Simulation to Update Concepts of Difficult Airway Management for Experienced Airway Practitioners

Background: We integrated lecture, real‐time multimedia display and medical simulation into a new renewal airway management training protocol for experienced nurse anesthetists. Methods: Trainees of the Taiwan Association of Nurse Anesthetists from northern Taiwan and junior residents from our department were enrolled into the training program. A 4‐hour renewal curriculum in the management of airway emergen‐cies was developed, which consisted of a 2‐hour general lecture (including 4 divided sections) and a 2‐hour instructor‐based real‐time multimedia medical simulation of 4 specific techniques. After detailed explanation of each specific instrument at the beginning of each simulation, the instructors demonstrated accurate and successful management of 4 airway crises from clinical experience by using a standardized human patient simulator situated on the stage of the conference room. Meanwhile, real‐time display of instructors’ performance, responsive physical parameters and images from specific instruments were conducted by video camera and video processor, and projected on a 3‐frame screen. Brief summary and feedback were performed after each simulation. Trainees completed a questionnaire 6 months after they participated in the training program. Results: Two hundred and forty‐two nurse anesthetists and 13 young residents were trained with this protocol. The questionnaire revealed that the renewal training program was useful. Participants updated their knowledge of difficult airway management, gained more confidence, improved performance, and provided effective assistance in handling airway crises. Conclusion: Renewing practice guidelines and teaching airway management skills, especially for difficult airway crises and protection of personnel, continues to be an important issue. Instructor‐based real‐time multimedia simulation is a fast, useful and systematic renewal educational method for many participants with extensive experience of airway management to update their knowledge about difficult airway management, and acquire improved decision‐making and communication capabilities, skills of specific airway management. [J Chin Med Assoc 2008;71(4):174–179]

Carbon dioxide embolism diagnosed by transesophageal echocardiography during endoscopic vein harvesting for coronary artery bypass grafting.

IMPLICATIONS We describe a case of massive carbon dioxide embolism with an abrupt decrease in arterial blood pressure and continuous mixed venous oxygen saturation during endoscopic vein harvesting that was immediately diagnosed by intraoperative transesophageal echocardiography.

Prevention of Dental Damage and Improvement of Difficult Intubation Using a Paraglossal Technique With a Straight Miller Blade

Patients with diseased teeth, or those who are difficult to intubate, have a higher risk of dental injury during laryngoscopy. We report 3 cases of smooth endotracheal intubation using a paraglossal technique with a straight Miller blade in patients with poor dentition. Three patients with poor dentition were scheduled to undergo surgery under general anesthesia. All patients presented with extremely loose upper central incisors and had lost the other right upper teeth, while micrognathia and prominent, loose upper incisors were noted in 1 case. We elected to use a straight Miller blade using a paraglossal approach. A nasopharyngeal airway was inserted after induction of general anesthesia to facilitate mask ventilation and prevent air leakage from the mask. The Miller blade was then inserted from the right corner of the mouth, avoiding contact with the vulnerable incisors, and advanced along the groove between the tongue and tonsil. The endotracheal tube was subsequently smoothly inserted after obtaining a grade 1 Cormack and Lehane view without dental trauma in all 3 cases. Direct laryngoscopy using the paraglossal straight blade technique avoids dental damage in patients with mobile upper incisors and no right maxillary molars. It is a practical alternative method that differs from the traditional Macintosh laryngoscope in patients with a high risk of dental injury during the procedure. This technique, which provides an improved view of the larynx, might also be helpful with patients in whom intubation is difficult.

Detection of Right to Left Shunt by Transesophageal Echocardiography in a Patient with Postoperative Hypoxemia

Intracardiac right to left shunt through a patent foramen ovale (PFO) may result in the development of hypoxemia after cardiac surgery. Cardiac tamponade and mechanical ventilation with high positive endexpiratory pressure are the most common factors responsible for enhancing intracardiac right to left shunt through a PFO. We report an 83-year-old woman with Stanford type A dissecting aneurysm who developed hypoxemia and paradoxical air embolism after reconstruction of ascending aorta and Bentals procedure. Transesophageal echocardiography (TEE) revealed right to left shunting via a PFO. Surgical closure of the PFO was done without delay. This case illustrates the role of TEE in prompt diagnosis of intracardiac right to left shunting through a PFO causing postoperative hypoxemia after cardiac surgery.

Acute effect of methylprednisolone on the brain in a rat model of allergic asthma

Asthma affects not only the airways but also the central nervous system (CNS). Corticosteroids are an effective therapeutic agents for asthma. In our study, we investigated the acute effect of ovalbumin (OVA) on the brain and the effectiveness of methylprednisolone (MP) in both the periphery and CNS in a rat model of allergic asthma. Rats sensitized to OVA and exposed to OVA aerosol challenge to induce allergic asthma were compared with control rats and rats sensitized to OVA and pretreated with MP before OVA exposure. In response to OVA stimulation, the amount of c-Fos and glial fibrillary acidic protein (GFAP) increased, while that of neuronal nitric oxide synthase (nNOS) decreased in the nucleus tractus solitarius (NTS). In addition, the c-Fos, GFAP, and nNOS levels in the hippocampus and the nNOS levels in the olfactory bulb increased. However, the expression of these proteins in the frontal and cerebellar cortices was not affected by OVA stimulation. In contrast, pretreatment with MP before OVA exposure decreased the protein expression of c-Fos in the CA1 area, GFAP in NTS, and nNOS in CA1 and olfactory bulb, and while it increased the nNOS content in the NTS. These findings suggest that the brain responds to OVA stimulation in a rat model of allergic asthma and that MP treatment cannot only ameliorate airway inflammation but also OVA-induced effects.

Practical preprocedure measurement to estimate the required insertion depth and select the optimal size of tunneled dialysis catheter in uremic patients.

We evaluated two methods for preprocedure predicting the insertion depth of tunneled dialysis catheter (TDC) on chest radiograph (CXR). Patients undergoing TDC insertion via right internal jugular vein were enrolled. By Method 1, the insertion depth was calculated on preprocedure CXR as the distance from the anticipated venous tip (3.5 cm below the cavoatrial junction) to the prearranged skin puncture site (1.5 cm above the right clavicle). By Method 2, the insertion depth was derived by adding the length between the skin puncture site and the upper edge of the clavicle and the length of clavicle‐to‐tip. The TDC was placed at the estimated insertion depth. The distance of cavoatrial junction‐to‐arterial tip was then measured from postoperative supine CXR. One hundred and seventy and 121 TDCs were inserted by Method 1 and Method 2, respectively, while 127 and 92 preoperative supine CXR were used for preprocedure measurement. The mean distance of cavoatrial junction‐to‐arterial tip was 12.055 (8.5684) [mean (SD)], 11.27 (3.3261), 9.524 (5.1590), and 10.538 (2.6956) mm. Methods of determining the insertion depth by preprocedure measurement enable successful TDC tip placement. Method 2 and using preoperative supine CXR enabled more precise and flexible insertion.