The Influence of Body Mass Index on Sensorimotor Block and Vasopressor Requirement During Spinal Anesthesia for Elective Cesarean Delivery.

BACKGROUND: It has been suggested that the dose requirement for spinal anesthesia (SA) is lower in obese patients for cesarean delivery (CD). In this prospective, observational, noninferiority study, we tested the hypothesis that obesity would not have a clinically important effect on vasopressor requirements or block height. METHODS: Two groups of 25 parturients, group O (body mass index [BMI] >40 kg/m) and group N (BMI <32 kg/m) requiring elective CD were recruited. All patients received 10 mg intrathecal hyperbaric bupivacaine coadministered with 10 µg fentanyl. Dermatomal levels were assessed at 5 and 25 minutes after SA, and at completion of surgery, using light touch and cold sensation in response to ethyl chloride. The primary outcomes were phenylephrine requirement in the first 30 minutes after SA, and maximum block height, measured by the sensation of touch and cold. Secondary outcomes were total phenylephrine dose required, changes in hand grip strength, and peak flow rate. RESULTS: There were no significant between-group differences in median block height as assessed by touch at 5 or 25 minutes or by temperature at 5 minutes. At 25 minutes, there was a 2-dermatome difference in median block height for loss of temperature sensation between group O and group N (T2 vs T4, 95% confidence interval [CI] of the difference in medians 0-2 dermatomes). No blocks extended to cervical dermatomes. The median (range) phenylephrine dose for the first 30 minutes was 150 µg (0-900 µg), and 100 µg (0-1250 µg) in group N and group O, respectively. The 95% CI for the difference between the 2 median doses was -150 µg to 100 µg. There were no differences in median percentage reductions in peak flow rate or median hand grip strength after SA. Mean surgical time was longer in group O than in group N (49.1 vs 39.4 min, 95% CI difference 1.7-17.7 min). The mean time for recovery of touch sensation to T10 was longer in group O (152 vs 132 min, 95% CI difference 3.8-36.2 min). No analgesic supplementation was required. CONCLUSION: Only a minor increase in block height as assessed by temperature occurred in group O at 25 minutes. Vasopressor requirements during the first 30 minutes of SA were equivalent. Time for regression of SA block level was longer in the group O, which may be beneficial considering the longer surgical time. A dose of spinal bupivacaine 10 mg for single-shot SA should not be reduced in morbidly obese parturients.

Impact of oral meloxicam on circulating physiological biomarkers of stress and inflammation in beef steers after long-distance transportation.

Transportation stress can result in significant economic losses to producers due to decreased animal productivity and increased medication costs associated with sickness such as bovine respiratory disease (BRD). Meloxicam (MEL) provides pain relief and anti-inflammatory effects in cattle for several days after a single oral treatment. Our hypothesis was that MEL administration before shipping would reduce the impact of long-distance transportation on circulating physiological biomarkers of stress and inflammation in beef steers. Ninety-seven beef steers were blood sampled for baseline biomarker determination and then randomly assigned to receive either 1 mg/kg MEL (n = 49) or a placebo (CONT; n = 48) per os before a 1,316-km transportation event lasting approximately 16 h. Calves were then blood sampled on arrival and 5 d later. Changes in the hemogram, circulating plasma proteins, total carbon dioxide (TCO2), fibrinogen, substance P (SP), cortisol, haptoglobin (Hp)-matrix metalloproteinase-9 (MMP-9) complexes, and tumor necrosis factor α (TNFα) between treatments over time were compared using a mixed effects model with statistical significance designated as P < 0.05. Analysis of covariance was conducted to assess the relationship between circulating MEL concentrations and biomarker changes over time. An increase in neutrophil, platelet, monocyte, white blood cell, and red blood cell counts occurred after transportation (P < 0.0001) and a decrease in lymphocyte count were observed (P < 0.0001). Meloxicam treatment reduced the stress-induced neutrophilia (P = 0.0072) and circulating monocyte count (P = 0.013) on arrival. Mean corpuscle hemoglobin (P = 0.05), mean corpuscle volume (P = 0.05), and lymphocyte count (P = 0.05) were also greater in the CONT calves compared with MEL calves after transportation. Furthermore, Hp-MMP-9 complexes, TCO2, TNFα, plasma proteins, and SP increased and cortisol decreased after shipping (P < 0.01). Meloxicam treatment tended to reduce serum cortisol concentrations (P = 0.08) and there was evidence of a time × treatment interaction (P = 0.04). An inverse relationship between plasma MEL concentrations and circulation cortisol concentrations (P = 0.002) and neutrophil (P = 0.04) and basophil counts (P = 0.03) was also observed. The results suggest that MEL administration may reduce the impact of long-distance transportation on circulating physiological biomarkers of stress and inflammation in beef calves.

Electroejaculation increased vocalization and plasma concentrations of cortisol and progesterone, but not substance P, in beef bulls.

Electroejaculation is a reliable method of obtaining a semen sample for a bull breeding soundness examination, but is sometimes regarded as painful. Substance P is a neuropeptide involved in the integration of pain, stress, and anxiety. We hypothesized that substance P is a measure of pain in bulls following electroejaculation. The specific objective was to compare vocalization and plasma concentrations of cortisol, progesterone, and substance P immunoreactivity in bulls following electroejaculation. Nine Angus bulls (501.9 ± 14.3 kg) were used. Blood samples were collected at -60, -30, 0, 2, 10, 20, 30, 45, 60, 75, 90, 120 min relative to treatment. At Time 0, bulls were subject to electroejaculation, rectal probe insertion without electroejaculation, or no manipulation. Treatments were administered contemporaneously to three bulls. Treatments were repeated weekly until each bull had received each treatment in a 3 × 3 Latin square design. More bulls (P = 0.0147) in the electroejaculation group vocalized (5 of 9 bulls; 55.6%) when compared to controls (0 of 9 bulls; 0%). Mean plasma cortisol and progesterone concentration following electroejaculation in bulls were higher (P < 0.05) than concentrations in probed and control bulls through the 45 min sample. However, mean plasma substance P concentration following electroejaculation in bulls (77.2 ± 17.2 pg/mL) was not different (P = 0.6264) from probed (79.1 ± 17.2 pg/mL) or control bulls (93.4 ± 17.2 pg/mL). A significant increase in vocalization and plasma cortisol and progesterone concentrations in bulls following electroejaculation was likely owing to acute stress. However, the lack of a difference in plasma concentrations of substance P after electroejaculation was interpreted as a lack of pain associated with nociception.

Fresh gas flow is not the only determinant of volatile agent consumption: a multi-centre study of low-flow anaesthesia.

METHODS: Seven academic centres studied 302 patients, using desflurane, enflurane, halothane, or isoflurane using circle-systems and Dräger Julian anaesthetic machines, with fresh gas flows (V(F)) of 3, 1, and 0.5 litre min(-1). Volatile agent partial pressures in the breathing system were recorded and agent consumptions measured by weighing. RESULTS: At these flows, desflurane consumption depended on V(F). In contrast, halothane consumption was not influenced by V(F). Isoflurane and enflurane showed differences in consumption between flows of 0.5 and 3 litre min(-1). Stepwise linear regression suggested that besides V(F), other factors influenced consumption of the more soluble agents (sex, age, weight, height, altitude, and temperature). The partial pressure ratios were independent of V(F) for desflurane (end-tidal to fresh gas=0.8), but the ratios of the more soluble agents varied with V(F) (end-tidal to fresh gas=0.3-0.7). CONCLUSIONS: At V(F) that involves significant re-breathing, consumption of soluble agents depends only partially on V(F). These results can be explained using Mapleson's hydraulic analogue model.

Reduction of postischemic contractile dysfunction of the isolated rat heart by sevoflurane: comparison with halothane.

Our aims were to evaluate the effect of sevoflurane on postcardioplegic functional recovery of the isolated rat heart including the role of the adenosine triphosphate regulated potassium (K(ATP)) channels and to compare the cardioprotective effects of equipotent concentrations of halothane and sevoflurane. Isolated perfused rat hearts were subjected to 45 or 60 min normothermic cardioplegic arrest and 30 min reperfusion. Sevoflurane (0.9% and 1. 7%), halothane (0.4% and 0.8%), or sevoflurane (0.9%) plus glibenclamide (10 microM) (a K(ATP) channel blocker) were administered at different time intervals. Measurements of mechanical activity were made before and after arrest. Function during reperfusion after cardioplegic arrest was significantly depressed in both untreated and treated hearts. However, sevoflurane administered both before and after arrest, or before only, significantly improved functional recovery after 45 min of cardioplegia. This protective effect was abolished by simultaneous administration of glibenclamide, suggesting a role of the K(ATP) channel. Sevoflurane was as effective as halothane in improving postcardioplegic functional performance. After 45 min of arrest, hearts exposed to either anesthetic at both concentrations had a significantly higher work performance on discontinuation of their administration than untreated controls. After 60 min of arrest, neither anesthetic elicited protection.

Tramadol today.

Tramadol is a unique analgesic offering moderate, dose-related pain relief through its action at multiple sites. In contrast to pure opioid agonists, it has a low risk of respiratory depression, tolerance and dependence. Troublesome side-effects have been reported, but tramadol has been established as an adjunct to non-steroidal anti-inflammatory drugs in the treatment of moderate postoperative pain and to abolish shivering. It may have advantages in paediatric and day-case surgery and as an adjunct in local anaesthetic techniques. This review provides an evidence-based account of the role of tramadol in modern practice.

Tramadol or morphine administered during operation: a study of immediate postoperative effects after abdominal hysterectomy.

Tramadol may cause awareness and EEG activation during anaesthesia. We compared tramadol with morphine, administered during wound-closure, surmising that tramadol may cause earlier awakening, more rapid recovery, less respiratory depression and equivalent pain relief. Forty patients received nitrous oxide-enflurane for abdominal surgery. At wound closure, patients received tramadol 3 mg kg-1 or morphine 0.2 mg kg-1 and end-tidal enflurane concentrations were maintained at 0.5 kPa until skin closure, whereupon anaesthesia was discontinued. Times to spontaneous respiration, awakening and orientation were similar in the two groups, as were blood-gas tensions, ventilatory frequency, pain scores and incidence of nausea. Half of each group required supplementary analgesia during their 90-min stay in the recovery room. P-deletion counts improved more rapidly in the tramadol group. This study confirms previous reports that tramadol did not antagonize the hypnotic effects of volatile anaesthetics. Tramadol, administered during operation, was as effective as morphine in providing postoperative analgesia while permitting more rapid psychomotor recovery.

Pharmacokinetic behaviour and cardiovascular effects of intravenously administered hypoxoside and rooperol.

This study concerns the pharmacokinetic behaviour and cardiovascular effects of rapid infusions of hypoxoside (CAS 83643-94-1) and rooperol (CAS 83644-00-2) in anaesthetised Chacma baboons. Institutional approval was obtained and animal care conformed to international guidelines. Hypoxoside (500 mg) and rooperol (240 mg) dissolved in isotonic saline were infused during 15 min. Concentration-time data from high performance liquid chromatography of arterial blood samples were subjected to non-linear curve-fitting to obtain two-compartment mammillary pharmacokinetic models. Mean values were: [Table: see text] Hypoxoside was eliminated without significant metabolite formation and it revealed no cardiovascular effects. Rooperol was metabolized rapidly with formation of nine metabolites of which the major three were the diglucuronide, disulphate and mixed glucuronide sulphate. Rooperol caused moderate, transient increased cardiac output, stroke volume and vascular pressures without increased heart rate or filling pressures, suggestive of increased myocardial contractility probably allied to its catechol structure.

Intra-ocular concentration-time relationships of subconjunctivally administered gentamicin.

Eighty-nine patients scheduled for cataract removal or lens implantation were divided randomly into three groups. Each received 5, 10 or 20 mg gentamicin subconjunctivally at times varying between 0.2 and 19 hours pre-operatively. At surgery a sample of aqueous humour was obtained and analysed for gentamicin concentration. The data for each group were subjected to non-linear regression analysis to fit an open one-compartment pharmacokinetic model with first-order kinetics. A statistically acceptable fit was obtained. The average values of the pharmacokinetic parameters obtained from the single doses were used to simulate multiple-dose kinetics. The average target intra-ocular gentamicin concentrations and dosage interval were specified in the computer program, which subsequently allowed calculation of the dose required. This allowed the construction of a simple linear nomogram that can be used to read off the dose needed for handling specific clinical situations.