Comparison of the venous-arterial CO2 to arterial-venous O2 content difference ratio with the venous-arterial CO2 gradient for the predictability of adverse outcomes after cardiac surgery.

This study aimed to compare the prognostic performance of the ratio of mixed and central venous-arterial CO2 tension difference to arterial-venous O2 content difference (Pv-aCO2/Ca-vO2 and Pcv-aCO2/Ca-cvO2, respectively) with that of the mixed and central venous-to-arterial carbon dioxide gradient (Pv-aCO2 and Pcv-aCO2, respectively) for adverse events after cardiac surgery. One hundred and ten patients undergoing cardiac surgery with cardiopulmonary bypass were enrolled. After catheter insertion, three blood samples were withdrawn simultaneously through arterial pressure, central venous, and pulmonary artery catheters, before and at the end of the operation, and preoperative and postoperative values were determined. The primary end-point was set as the incidence of postoperative major organ morbidity and mortality (MOMM). Receiver operating characteristic (ROC) curve and multivariate logistic regression analyses were performed to evaluate the prognostic reliability of Pv-aCO2, Pcv-aCO2, Pv-aCO2/Ca-vO2, and Pcv-aCO2/Ca-cvO2 for MOMM. MOMM events occurred in 25 patients (22.7%). ROC curve analysis revealed that both postoperative Pv-aCO2/Ca-vO2 and Pcv-aCO2/Ca-cvO2 were significant predictors of MOMM. However, postoperative Pv-aCO2 was the best predictor of MOMM (area under the curve [AUC]: 0.804; 95% confidence interval [CI] 0.688-0.921), at a 5.1-mmHg cut-off, sensitivity was 76.0%, and specificity was 74.1%. Multivariate analysis revealed that postoperative Pv-aCO2 was an independent predictor of MOMM (odds ratio [OR]: 1.42, 95% CI 1.01-2.00, p = 0.046) and prolonged ICU stay (OR: 1.45, 95% CI 1.05-2.01, p = 0.024). Pv-aCO2 at the end of cardiac surgery was a better predictor of postoperative complications than Pv-aCO2/Ca-vO2 and Pcv-aCO2/Ca-cvO2.

General Anesthesia Management for Adult Mucopolysaccharidosis Patients Undergoing Major Spine Surgery.

OBJECTIVE: Mucopolysaccharidosis (MPS) are a group of rare systemic lysosomal storage diseases associated with severe airway obstruction and cardiac disease, making anesthesia management difficult. Contemporary treatment extends the lifespan of affected individuals, increasing the need for major surgery in adulthood. CLINICAL PRESENTATION AND INTERVENTION: We provided general anesthesia for 6 adult MPS patients undergoing spine surgery. The airway was assessed as difficult in all, with 2 receiving awake fiberoptic intubation and 1 successfully undergoing video-laryngoscopy, while 3 video-laryngoscopy procedures failed and required conversion to fiberoptic intubation. One patient developed ventricular fibrillation. CONCLUSION: Adult MPS patients have substantial anesthesia risk.

In-line positioning of ultrasound images using wireless remote display system with tablet computer facilitates ultrasound-guided radial artery catheterization.

Ultrasound-guided procedures may be easier to perform when the operator's eye axis, needle puncture site, and ultrasound image display form a straight line in the puncture direction. However, such methods have not been well tested in clinical settings because that arrangement is often impossible due to limited space in the operating room. We developed a wireless remote display system for ultrasound devices using a tablet computer (iPad Mini), which allows easy display of images at nearly any location chosen by the operator. We hypothesized that the in-line layout of ultrasound images provided by this system would allow for secure and quick catheterization of the radial artery. We enrolled first-year medical interns (n = 20) who had no prior experience with ultrasound-guided radial artery catheterization to perform that using a short-axis out-of-plane approach with two different methods. With the conventional method, only the ultrasound machine placed at the side of the head of the patient across the targeted forearm was utilized. With the tablet method, the ultrasound images were displayed on an iPad Mini positioned on the arm in alignment with the operator's eye axis and needle puncture direction. The success rate and time required for catheterization were compared between the two methods. Success rate was significantly higher (100 vs. 70 %, P = 0.02) and catheterization time significantly shorter (28.5 ± 7.5 vs. 68.2 ± 14.3 s, P < 0.001) with the tablet method as compared to the conventional method. An ergonomic straight arrangement of the image display is crucial for successful and quick completion of ultrasound-guided arterial catheterization. The present remote display system is a practical method for providing such an arrangement.

Effects of tramadol on substantia gelatinosa neurons in the rat spinal cord: an in vivo patch-clamp analysis.

Tramadol is thought to modulate synaptic transmissions in the spinal dorsal horn mainly by activating µ-opioid receptors and by inhibiting the reuptake of monoamines in the CNS. However, the precise mode of modulation remains unclear. We used an in vivo patch clamp technique in urethane-anesthetized rats to determine the antinociceptive mechanism of tramadol. In vivo whole-cell recordings of spontaneous inhibitory postsynaptic currents (sIPSCs) and spontaneous excitatory postsynaptic currents (sEPSCs) were made from substantia gelatinosa (SG) neurons (lamina II) at holding potentials of 0 mV and -70 mV, respectively. The effects of intravenous administration (0.5, 5, 15 mg/kg) of tramadol were evaluated. The effects of superfusion of tramadol on the surface of the spinal cord and of a tramadol metabolite (M1) were further analyzed. Intravenous administration of tramadol at doses >5 mg/kg decreased the sEPSCs and increased the sIPSCs in SG neurons. These effects were not observed following naloxone pretreatment. Tramadol superfusion at a clinically relevant concentration (10 µM) had no effect, but when administered at a very high concentration (100 µM), tramadol decreased sEPSCs, produced outward currents, and enhanced sIPSCs. The effects of M1 (1, 5 mg/kg intravenously) on sEPSCs and sIPSCs were similar to those of tramadol at a corresponding dose (5, 15 mg/kg). The present study demonstrated that systemically administered tramadol indirectly inhibited glutamatergic transmission, and enhanced GABAergic and glycinergic transmissions in SG neurons. These effects were mediated primarily by the activation of µ-opioid receptors. M1 may play a key role in the antinociceptive mechanisms of tramadol.

Use of tricyclic antidepressants as analgesic adjuvants results in nonhazardous prolongation of the QTc interval.

BACKGROUND: Tricyclic antidepressants (TCAs) are known to prolong QTc interval. However, little is known about the QTc lengthening effect of TCAs at analgesic dosages and the predictive factors for abnormal QTc prolongation. METHODS: We conducted a single-center, retrospective observational study, and evaluated 87 patients (65 amitriptyline, 22 nortriptyline) who underwent 12-lead electrocardiogram (ECG) examinations both before and after receiving TCAs for herpes zoster pain or postherpetic neuralgia from May 2007 to January 2012. Data on QTc interval, age, gender, the type and daily dosage of TCAs, the medication period until the second ECG examination, and ECG findings were obtained from electronic medical charts. RESULTS: The median daily dosages were 25 mg/day for amitriptyline and 10 mg/day for nortriptyline. The median medication period for all participants was 62 days. TCAs significantly prolonged the QTc interval (before, 413.2 +/-17.0 ms; after, 419.9 +/- 18.9 ms, p < 0.01). Three patients showed marked QTc prolongation, but it did not exceed 500 ms, or deltaQTc of 60 ms, and none had an episode of fatal arrhythmia. Univariate logistic regression analysis revealed left ventricular hypertrophy (LVH) to be the sole risk factor for abnormal QTc prolongation. The adjusted odds ratio was 4.09 (95% CI, 1.01-16.55, p < 0.05) by multivariate logistic regression analysis. CONCLUSIONS: TCAs as analgesic adjuvant significantly prolonged the QTc interval, but within an acceptable range. LVH was a significant predictor of abnormal QTc prolongation.

The impact of intraoperative hypothermia on early postoperative adverse events after radical esophagectomy for cancer: a retrospective cohort study.

OBJECTIVE: To investigate the correlation between intraoperative body temperature and postoperative adverse effects in patients who underwent esophagectomy procedures. DESIGN: Retrospective cohort study. SETTING: University Hospital. PARTICIPANTS: One hundred twenty-one patients undergoing esophagectomy were enrolled. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Various perioperative and intraoperative variables were recorded. Hypothermia was defined as a urinary bladder temperature<35°C. Multiple logistic regression analysis was conducted to identify independent significant predictors of postoperative complications. In addition, the authors also determined a cutoff point for intraoperative minimum urinary bladder temperature by analyzing receiver operating characteristic (ROC) curves for occurrence of adverse events at 1 month after surgery. No patients died within 1 month after the surgery. There were 53 patients with early postoperative complications, and 51 had experienced intraoperative hypothermia. Factors that were correlated significantly with complications included age (p=0.02); hypothermia (p<0.01); and doses of ephedrine (p<0.01), phenylephrine (p<0.01), and fentanyl (p<0.01). Multiple logistic regression analysis identified intraoperative hypothermia as a significant independent predictor for the development of early perioperative complications (odds ratio 2.57; 95% confidence interval 1.09-6.08). The area under the ROC curve for body temperature was 0.71, and the cutoff point was 35°C (sensitivity=0.65, specificity=0.72). CONCLUSIONS: Intraoperative hypothermia was identified as an independent risk factor for early postoperative adverse events following esophagectomy.

Systemic dexmedetomidine augments inhibitory synaptic transmission in the superficial dorsal horn through activation of descending noradrenergic control: an in vivo patch-clamp analysis of analgesic mechanisms.

α2-Adrenoceptors are widely distributed throughout the central nervous system (CNS) and the systemic administration of α2-agonists such as dexmedetomidine produces clinically useful, centrally mediated sedation and analgesia; however, these same actions also limit the utility of these agents (ie, unwanted sedative actions). Despite a wealth of data on cellular and synaptic actions of α2-agonists in vitro, it is not known which neuronal circuits are modulated in vivo to produce the analgesic effect. To address this issue, we made in vivo recordings of membrane currents and synaptic activities in superficial spinal dorsal horn neurons and examined their responses to systemic dexmedetomidine. We found that dexmedetomidine at doses that produce analgesia (<10 µg/kg) enhanced inhibitory postsynaptic transmission within the superficial dorsal horn without altering excitatory synaptic transmission or evoking direct postsynaptic membrane currents. In contrast, higher doses of dexmedetomidine (>10 µg/kg) induced outward currents by a direct postsynaptic action. The dexmedetomidine-mediated inhibitory postsynaptic current facilitation was not mimicked by spinal application of dexmedetomidine and was absent in spinalized rats, suggesting that it acts at a supraspinal site. Furthermore, it was inhibited by spinal application of the α1-antagonist prazosin. In the brainstem, low doses of systemic dexmedetomidine produced an excitation of locus coeruleus neurons. These results suggest that systemic α2-adrenoceptor stimulation may facilitate inhibitory synaptic responses in the superficial dorsal horn to produce analgesia mediated by activation of the pontospinal noradrenergic inhibitory system. This novel mechanism may provide new targets for intervention, perhaps allowing analgesic actions to be dissociated from excessive sedation.

Remifentanil increases the incidence of mesenteric traction syndrome: preliminary randomized controlled trial.

PURPOSE: The use of remifentanil is often associated with the observation of mesenteric traction syndrome (MTS) soon after manipulation of the intestine during abdominal surgery. MTS symptoms include facial flushing, hypotension, and tachycardia. In the study reported here, we prospectively investigated the effects of remifentanil on the incidence of MTS in abdominal surgery. METHODS: One hundred patients scheduled for abdominal surgery were randomly assigned to two groups. In one group (n = 50), fentanyl alone was used as intravenous analgesic (control, group C); in the second group (n = 50), both fentanyl and remifentanil were used (remifentanil group, group R). In all patients, anesthesia was induced with propofol and rocuronium and then maintained with sevoflurane inhalation. Remifentanil was continuously infused for patients in group R as an analgesic. Plasma concentration of 6-keto-PGF(1α) was measured before surgery and 20 min after the skin incision was made in six patients of group R and seven patients of group C. RESULTS: MTS occurred in 20 cases in group R (40.0%), but in only five cases in group C (10.0%). In both groups, the incidence of MTS was higher in laparotomy than in laparoscopic surgery. The plasma concentration of 6-keto-PGF(1α) was low in both groups before surgery and was elevated 20 min after skin incision in both groups in patients in whom MTS appeared. CONCLUSIONS: The results of this study suggest that the use of remifentanil in laparotomy facilitates MTS.

[Prolonged apnea from rocuronium in a patient with hypermagnesemia after cesarean section: a case report].

A patient developed prolonged apnea after emergency cesarean section. The patient was a 38-year-old primiparous woman with myoma uteri and her body weight was 44.8 kg. She received intravenous magnesium sulfate 1 g x hr(-1) as tocolytic agent for threatened premature delivery. We performed rapid sequence induction of anesthesia with thiopental 250 mg and rocuronium 50 mg because she was suspected of full stomach. After the intubation, we did not administer any muscle relaxants during the operation. After the operation which was finished in 65 minutes, the effect of rocuronium remained for more than 100 minutes after its administration probably due to hypermagnesemia. Rocuronium shows rapid onset, and several studies indicate that it can be used for rapid sequence induction instead of suxamethonium. But rocuronium should be used carefully and its effect should be monitored in a patient with hypermagnesemia.