Hector J. Lacassie

The relative motor blocking potencies of epidural bupivacaine and ropivacaine in labor.

Minimal local analgesic concentrations (MLAC) have been used to determine the epidural analgesic potencies of bupivacaine and ropivacaine. There are no reports of the motor blocking potencies of these drugs. We sought to determine the motor block MLAC of both drugs and their relative potency ratio. Sixty ASA physical status I and II parturients were randomized to one of two groups, during the first stage of labor. Each received a 20-mL bolus of epidural bupivacaine or ropivacaine. The first woman in each group received 0.35%. Up-down sequential allocation was used to determine subsequent concentrations at a testing interval of 0.025%. Effective motor block was defined as a Bromage score <4 within 30 min. The up-down sequences were analyzed by using the Dixon and Massey method and probit regression to quantify the motor block minimal local analgesic concentration. Two-sided P < 0.05 defined significance. The motor block minimal local analgesic concentration for bupivacaine was 0.326% (95% confidence interval [CI], 0.285–0.367) and for ropivacaine was 0.497% (95% CI, 0.431–0.563) (P = 0.0008). The ropivacaine/bupivacaine potency ratio was 0.66 (95% CI, 0.52–0.82). This is the first MLAC study to estimate the motor blocking potencies of bupivacaine and ropivacaine. Ropivacaine was significantly less potent for motor block, at 66% that of bupivacaine.

The relationship between neuraxial anesthesia and advanced ovarian cancer-related outcomes in the Chilean population.

BACKGROUND:Mixed evidence has been published relating the use of regional anesthesia during oncologic surgery to a decrease in time to cancer recurrence and improvement in overall survival. We investigated whether the use of epidural anesthesia, in addition to general analgesia during and/or after surgical removal of advanced ovarian cancer, has an impact on time to recurrence and overall survival. METHODS:Patients were identified from a prospective clinical registry. Eighty patients with advanced ovarian cancer (International Federation of Gynecologists and Obstetricians, stage IIIC and IV) undergoing surgery between January 2000 and March 2011 were studied. Propensity scoring (PS) methods (matching and inverse weighting) were used to compare the time to recurrence and overall survival of patients who did and did not receive epidural anesthesia and/or analgesia (EA), after controlling for selection bias. RESULTS:The median time to recurrence was 1.6 and 0.9 years for the EA and no EA groups, respectively (P = 0.02). After PS matching, the median time to recurrence was 1.6 and 1.4 years for the EA and no EA groups, respectively (P = 0.30). Similarly, PS weighting did not demonstrate an improvement in time to recurrence with the use of EA. Using a Cox proportional hazards model in the PS-matched sample, the estimated hazard ratio for EA exposure (0.72; 95% confidence interval [CI], 0.40–1.33) did not change substantially after adjusting for chemotherapy (0.73; 95% CI, 0.40–1.31). Similar results were obtained using PS weighting. The median survival time was 3.3 and 1.9 years for the EA and no EA groups, respectively (P = 0.01). After PS matching, the median survival time was 3.3 and 2.7 years for the EA and no EA groups, respectively (P = 0.37). Similarly, PS weighting did not demonstrate an improved survival with the use of EA. The estimated hazard ratio (0.74; 95% CI, 0.36–1.49) in the PS matched sample did not change substantially after adjusting for chemotherapy, with similar results when PS weighting was applied. CONCLUSIONS:After PS matching and weighting, we found no benefit in overall survival or time to recurrence in patients with advanced stages (International Federation of Gynecologists and Obstetricians IIIC and IV) of ovarian cancer after the use of EA during and after tumor debulking surgery.

A randomized, prospective double-blind comparison of the efficacy of generic propofol (sulphite additive) with Diprivan ®

Background and objective: We compared the dose requirement and side effect profile of total intravenous anaesthesia using Diprivan® to generic propofol at a specific anaesthetic target level utilizing the bispectral index monitor to determine efficacy differences between the two products. Methods: Sixty women undergoing abdominal hysterectomy were induced with propofol 2 mg kg−1 and maintained with infusion (20–200 μg kg−1 min−1) adjusted to maintain a bispectral index of 50–65. Plasma propofol concentration was measured at 1 and 2 h post induction in 25 patients. Results: Mean (SD) drug doses adjusted for weight and time were similar in the Diprivan® and generic propofol groups: 90 (30) μg kg−1 min−1 vs. 90 (20) μg kg−1 min−1 respectively. Mean (SD) plasma propofol levels at 1 and 2 h were also similar (3.0 (1.0) μg mL−1 vs. 3.6 (1.4) μg mL−1, P = 0.2 and 3.0 (1.9) μg mL−1 vs. 3.4 (1.6) μg mL−1, P = 0.58). Conclusions: Diprivan® and generic propofol have similar efficacy at a specified, bispectral index‐defined, depth of anaesthesia.

Is the minimum local analgesic concentration method robust enough

To the Editor:—We read with interest the articles by Polley et al. and Benhamou et al. in which they simultaneously published the same study in terms of objective and design performed on different continents. Minimum local analgesic concentration results, including the potency ratios, were surprisingly different from expectations. In a similar study comparing bupivacaine and ropivacaine minimum local analgesic concentrations, Polley et al. in the United States and Capogna et al. in Italy found different results although the exact same potency ratios. This makes us wonder if the current inconsistencies in results were just intercontinental differences or something else? The possible explanations we propose that were not commented in either study are as follows: 1) No real difference between the drugs. There were no statistical differences in either study, so we should accept the fact as it is. Why did this happen, having in mind all the evidence gathered so far that there is a potency rank? No clue, except for: 2) Chance, which is always a possibility. Here is our greatest concern about the method: When we study subtle differences (i.e., 15 or 20 percent), is the minimum local analgesic concentration method powerful enough to detect these differences without changing the number of subjects to be studied? As this issue is one of the strengths of the up and down sequential allocation method (to detect this clinically small difference), we might need more patients to be included in the design. We encourage the authors to deepen in the interpretation of the “negative” results. We are sure they are as surprised as we are. 3) End point: Is ED50 for pain relief in first-stage labor in the vicinity of the lower part of the dose-response curve for both drugs? Can this be the same kind of effect, but on the opposite part of the curve, when we use supramaximal doses and the potency relationship is lost? Maybe if we analyze another end point, namely motor block, a higher dosage requirement and potency differences will become more apparent. Finally, we agree with Benhamou et al. that further studies are required to verify this hypothesis.

Perioperative anesthetic management for Cesarean section of a parturient with gestational diabetes insipidus.

PurposeGestational diabetes insipidus (GDI) is a rare endocrinopathy complicating about 4:100,000 deliveries. We present the case of a preterm parturient with GDI and severe hypernatremia (serum sodium concentration = 174 mmol·L-1) presenting for an urgent Cesarean section.Clinical featuresFluid resuscitation and desmopressin supplementation partially corrected the patient’s homeostasis, allowing us to carefully titrate epidural anesthesia for an urgent Cesarean section. After delivery, the patient was transferred to the intensive care unit. The serum sodium concentration of the mother and the neonate was normalized over 48 hr and three days respectively.ConclusionThe careful perioperative management of GDI led to a favourable outcome of the mother and fetus.RésuméObjectifLe diabète insipide gestionnel (DIG) est une endocrinopathie rare dans environ 4:100 000 accouchements. Nous présentons le cas ďune parturiente avant terme, atteinte de DIG et ďhypernatrémie sévère (sodium sérique à 174 mmol·L-1 ), admise pour une césarienne ďurgence.Éléments cliniquesUne thérapie liquidienne et un ajout de desmopressine ont permis de corriger partiellement éhoméostasie et ďajuster soigneusement ľanesthésie péridurale pour la césarienne ďurgence. Après ľaccouchement, la patiente a été transférée à ľunité des soins intensifs. La concentration sérique de sodium de la mère et du nouveau-né a été normalisée, respectivement après 48 h et trois jours.ConclusionLa prise en charge périopératoire minutieuse du DIG a été favorable à la mère et à ľenfant.

World Health Organization (WHO) surgical safety checklist implementation and its impact on perioperative morbidity and mortality in an academic medical center in Chile.

AbstractHealth care organizations are unsafe. Numerous centers have incorporated the WHO Surgical Safety Checklist in their processes with good results; however, only limited information is available about its effectiveness in Latin America. We aimed to evaluate the impact of the checklist implementation on the in-hospital morbidity and mortality rate in a tertiary health care center. After Institutional review board approval, and using data from our hospital administrative records, we conducted a retrospective analysis of all surgical encounters (n = 70,639) over the period from January 2005 to December 2012. Propensity scoring (PS) methods (matching and inverse weighting) were used to compare the pre and postintervention period, after controlling for selection bias. After PS matching (n = 29,250 matched pairs), the in-hospital mortality rate was 0.82% [95% confidence interval (CI), 0.73–0.92] before and 0.65% (95% CI, 0.57–0.74) after checklist implementation [odds ratio (OR) 0.73; 95% CI, 0.61–0.89]. The median length of stay was 3 days [interquartile range (IQR), 1–5] and 2 days (IQR, 1–4) for the pre and postchecklist period, respectively (P < 0.01).This is the first Latin American study reporting a decrease in mortality after the implementation of the WHO Surgical Checklist in adult surgical patients. This is a strong and simple tool to make health care safer, especially in developing countries.

Motor Blocking Minimum Local Anesthetic Concentrations of Bupivacaine, Levobupivacaine, and Ropivacaine in Labor

Background and Objectives: Adequate comparison of blocking capabilities of local anesthetics should be done with some knowledge of their relative potencies. The objective of this clinical trial was to simultaneously determine the motor blocking minimum local anesthetic concentrations (MMLAC) and the relative potency ratios for racemic bupivacaine, levobupivacaine, and ropivacaine during labor. Methods: We studied parturients with singleton term pregnancies in vertex presentation. Each patient received a 20 mL epidural bolus of bupivacaine, levobupivacaine, or ropivacaine determined by the MMLAC model. Baseline and 30 min after injection, measurements of pain and muscle strength were performed, with assessment of motor strength in the legs at 30 min being the primary outcome measure. Results: There were no differences in demographic, hemodynamic, or obstetric characteristics between the patients receiving the three local anesthetics. The estimated MMLAC with the 95% confidence intervals (CI) were: Bupivacaine: 0.26% wt/vol (0.22‐0.30); Levobupivacaine: 0.30% wt/vol (0.25‐0.36); Ropivacaine: 0.34% wt/vol (0.29‐0.38). ANOVA of MMLAC estimates was significant (F = 3.32, P = .046), and when ranked by analgesic potencies, a significant linear trend (P = .014) to increasing motor blocking potencies from ropivacaine to levobupivacaine to bupivacaine was also found. Conclusions: This study confirms a motor blocking hierarchy for the three pipecoloxylidines.