The effect of intravenous ondansetron on maternal haemodynamics during elective caesarean delivery under spinal anaesthesia: a double-blind, randomised, placebo-controlled trial.

BACKGROUND: Spinal anaesthesia for caesarean delivery is frequently associated with adverse effects such as maternal hypotension and bradycardia. Prophylactic administration of ondansetron has been reported to provide a protective effect. We studied the effect of different doses of ondansetron in obstetric patients. METHODS: This prospective double-blind, randomised, placebo-controlled study included 128 healthy pregnant women scheduled for elective caesarean delivery under spinal anaesthesia. Women were randomly allocated into four groups (n=32) to receive either placebo or ondansetron 2, 4 or 8 mg intravenously before induction of spinal anaesthesia. Demographic, obstetric, intraoperative timing and anaesthetic variables were assessed at 16 time points. Anaesthetic variables assessed included blood pressure, heart rate, oxygen saturation, nausea, vomiting, electrocardiographic changes, skin flushing, discomfort or pruritus and vasopressor requirements. RESULTS: There were no differences in the number of patients with hypotension in the placebo (43.8%) and ondansetron 2mg (53.1%), 4 mg (56.3%) and 8 mg (53.1%) groups (P=0.77), nor the percentage of time points with systolic hypotension (7.3% in the placebo group and 11.1%, 15.7% and 12.6% in the ondansetron 2, 4 and 8 mg groups, respectively, P=0.32). There were no differences between groups in ephedrine (P=0.11) or phenylephrine (P=0.89) requirements and the number of patients with adverse effects. CONCLUSIONS: In our study, prophylactic ondansetron had little effect on the incidence of hypotension in healthy parturients undergoing spinal anaesthesia with bupivacaine and fentanyl for elective caesarean delivery.

[An update of the obstetrics hemorrhage treatment protocol]. / Actualización del protocolo de tratamiento de la hemorragia obstétrica.

Obstetric hemorrhage is still a major cause of maternal and fetal morbimortality in developed countries. This is an underestimated problem, which usually appears unpredictably. A high proportion of the morbidity of obstetric hemorrhage is considered to be preventable if adequately managed. The major international clinical guidelines recommend producing consensus management protocols, adapted to local characteristics and keep them updated in the light of experience and new scientific publications. We present a protocol updated, according to the latest recommendations, and our own experience, in order to be used as a basis for those anesthesiologists who wish to use and adapt it locally to their daily work. This last aspect is very important to be effective, and is a task to be performed at each center, according to the availability of resources, personnel and architectural features.

[Analgesic techniques for labour: alternatives in case of epidural failure]. / Técnicas analgésicas para el parto: alternativas en caso de fallo de la epidural.

Epidural analgesia is now the method of choice for the treatment of pain in labour and delivery. However, this technique may fail and provide inadequate or null alleviation to the mother. This paper reviews the risk factors, possible causes and possible therapeutic alternatives to inadequate analgesia, whether pharmacological therapies (neuroaxial, peripheral blocks or analgesic administration via intravenous or inhalational routes) or non-pharmacological ones (relaxation techniques, psychological or mechanical). In all possible cases the efficacy and indications of alternative therapies based on the published literature are reviewed, especially from the point of view of evidence-based medicine. The need is underscored of a multifactorial therapeutic approach to the pregnant woman, not just restricting ourselves to eliminating the pain of childbirth.

[Clinical and pharmacological study of the efficacy of carbetocin in elective caesareans compared to low and usual doses of oxytocin]. / Estudio clínico y farmacoeconómico de la eficacia de la carbetocina en cesáreas electivas respecto a la oxitocina a dosis bajas y a dosis habituales.

OBJECTIVES: To evaluate uterine contractility, bleeding, haemodynamic performance, and side effects of different doses of oxytocin after delivery under spinal anaesthesia in caesarean section without prior labour in childbirth. We also perform a pharmacoeconomic evaluation. MATERIAL AND METHODS: A randomised, descriptive, observational and multicentre prospective study was conducted, which included 104 ASA 1 patients divided into 3 groups. Group 1 (n=52) received after removal of the foetus and coinciding with foetal umbilical cord clamping, 1 IU of oxytocin followed by an infusion of 2.5 UI×h(-1); Group 2 (n=52) a continuous infusion of 20IU oxytocin at a rate of 700mUI×min(-1) followed later by 10UI×h(-1), and group 3, 100µg bolus dose of carbetocin only. RESULTS: There were no statistical differences between groups in anthropometric, obstetric or anaesthetic variables. Significant differences in uterine contraction in vaginal bleeding and the incidence of side effects, particularly headache and tremor, were more pronounced in the carbetocin group. CONCLUSIONS: With these results, we cannot recommend the routine use of carbetocin in caesarean sections, because it is accompanied by an increased incidence of side effects without any improvement in the prevention of obstetric haemorrhage. Finally, it is economically more expensive than the use of low doses of oxytocin, which may be the trend that should be considered in the future, due to the clinical outcomes, and its lower cost.

[Pharmacoeconomics: basic concepts and applications to clinical anesthesia]. / Fundamentos de farmacoeconomía y su aplicación en anestesia clínica.

The economic evaluation of medications and health care technology has gained importance in recent years. Health care resources are limited and their use must be optimized so that we can take the greatest possible advantage. Pharmacoeconomics seeks to analyze the best therapeutic drug choices to obtain the desired outcome in specific cases or in populations. The 4 approaches used in pharmacoeconomics are cost-minimization analysis, cost-benefit analysis, cost-effectiveness analysis, and cost-utility analysis. This review examines the characteristics of each type of study using examples from anesthesiology, a field in which pharmacoeconomics is beginning to play a role.

[Neuromuscular blockade monitoring. Part 1]. / Monitorización del bloqueo neuromuscular. 1a parte.

Many recent studies have underlined the importance of quantitative neuromuscular monitoring and the high incidence of residual block in clinical practice in spite of the use of nondepolarizing neuromuscular blockers of intermediate duration. Neuromuscular monitoring facilitates the tailoring of the muscular paralysis and appropriate patient recovery at the end of surgery. Monitoring also controls or prevents residual block and serves to guide the use of reversing agents. This review describes the physiology of neuromuscular junctions as well as the principles and patterns of nerve stimulation and clinical monitoring. In addition to drawing on their own experience, the authors have reviewed the literature available through evidence-based indexes and other databases up to December 2008. Most references found were case series and reviews. Quantitative monitoring is an evidence-based practice that should be applied in all situations in which a neuromuscular block is established.

[Effects of changes in ion concentrations, osmolarity, and pH on recovery from atracurium- or vecuronium-induced neuromuscular blockade]. / Efecto de las variaciones iónicas, la osmolaridad y el pH sobre la recuperación del bloqueo neuromuscular no despolarizante por atracurio y vecuronio.

OBJECTIVES: To determine changes in sodium, potassium, calcium, magnesium and chloride ion concentrations in blood, osmolarity, and pH during surgery, and to assess the influence of such changes on atracurium- or vecuronium-induced neuromuscular blockade under inhaled or intravenous anesthesia. MATERIAL AND METHODS: Prospective study randomizing 119 ASA 1-2 patients; 52.1% of the patients received atracurium (26.8%, with isoflurane; 25.2%, with propofol) and 47.9% received vecuronium (23.5%, with isoflurane; 24.3%, with propofol). The neuromuscular blockade was confirmed by electromyography of the adductor pollicis muscle (stimuli delivered to the cubital nerve). Two venous blood samples were extracted to measure ureic nitrogen, creatinine, glucose, ion concentrations (sodium, chloride, potassium, calcium, and magnesium), and osmolarity. Arterial blood gases and pH were also assessed. The first blood sample was extracted on inserting the venous catheter and the second on recovery of 25% of the first train-of-four twitch. RESULTS: The onset and duration of action for equipotent doses of atracurium and vecuronium were similar. Likewise, recovery was also similar. Plasma chloride ion and glucose levels tended to rise during surgery, while sodium, potassium and magnesium ion concentrations fell. Both total and effective plasma osmolarities also decreased. Fluid replacement therapy during surgery was at least partly responsible for these changes. Low calcium and magnesium concentrations and alkalosis prolonged some phases of atracurium recovery, while low sodium levels shortened the duration of some atracurium-induced blockade recovery phases. The effect of changes in chloride ion concentrations on recovery was variable. High chloride, low calcium, and especially low sodium ion concentrations shortened some phases of the vecuronium-induced blockade, while alkalosis prolonged its duration. CONCLUSIONS: Changes in electrolyte concentrations and pH as a result of standard fluid replacement therapy are moderate, well tolerated, and do not exercise a strong effect on the behavior of the neuromuscular blockade.

[Paresthesia and spinal anesthesia for cesarean section: comparison of patient positioning]. / Parestesias y anestesia subaracnoidea en cesáreas: estudio comparativo según la posición de la paciente.

OBJECTIVE: To determine the incidence of paresthesia during lumbar puncture performed with the patient in different positions. MATERIAL AND METHODS: A single-blind prospective study of patients scheduled for elective cesarean section, randomized to 3 groups. In group 1 patients were seated in the direction of the long axis of the table, with heels resting on the table. In group 2 they were seated perpendicular to the long axis of the table, with legs hanging from the table. In group 3 they were in left lateral decubitus position. Lumbar punctures were performed with a 27-gauge Whitacre needle. RESULTS: One hundred sixty-eight patients (56 per group) were enrolled. Paresthesia occurred most often in group 3 (P = .009). We observed no differences in blood pressure after patients moved from decubitus position to the assigned position. Nor did we observe between-group differences in blood pressure according to position taken during puncture. CONCLUSION: Puncture undertaken with the patient seated, heels on the table and knees slightly bent, is associated with a lower incidence of paresthesia than puncture performed with the patient seated, legs hanging from the table. Placing the patient's heels on the table requires hip flexion and leads to anterior displacement of nerve roots in the dural sac. Such displacement would increase the nerve-free zone on the posterior side of the sac, thereby decreasing the likelihood of paresthesia during lumbar puncture. A left lateral decubitus position would increase the likelihood of paresthesia, possibly because the anesthetist may inadvertently not follow the medial line when inserting the needle.