[Sciatic nerve block with 1% mepivacaine for foot surgery: posterior versus lateral approach to the popliteal fossa]. / Estudio comparativo del bloqueo del nervio ciático en el hueco poplíteo por abordaje posterior frente al abordaje lateral con mepivacaína al 1% para cirugía del pie.

AIMS: To compare the efficacy and feasibility of the sciatic nerve block performed using either a posterior or a lateral approach to the popliteal fossa, taking into consideration patient comfort during puncture and postoperative analgesia. PATIENTS AND METHODS: Sixty patients scheduled for foot surgery were randomly assigned to 2 groups: a posterior approach was used in performing the sciatic nerve block in 1 group (n = 30) and a lateral approach was in the other group (n = 30). The local anesthetic employed was mepivacaine 1%. RESULTS: Duration of sensory block was used significantly longer with the lateral approach (5.4 hours, range 3.3-8 hours) than with the posterior approach (4.4 hours, range 1.5-7 hours) (P < 0.001). Time to onset of the block was significantly shorter with the lateral approach (10 minutes, range 5-25 minutes) than with the posterior approach (17 minutes, range 4-45 minutes) (P < 0.01). Quality of the blockade was similar with both approaches. CONCLUSIONS: The lateral approach to the block of the sciatic nerve in the popliteal fossa provides analgesia comparable to that obtained with the posterior approach, with a faster onset and longer postoperative duration.

[Respiratory and hemodynamic effects of thoracic or lumbar epidural alfentanyl after thoracic surgery]. / Efectos respiratorios y hemodinámicos del alfentanilo epidural torácico o lumbar tras la cirugía torácica.

OBJECTIVES: The aim of this study was to evaluate the effects on pulmonary function and hemodynamics of three different types of analgesia after thoracotomy. MATERIAL AND METHODS: Forty-five ASA II-IV patients undergoing thoracotomy (for lobectomy or pneumonectomy) were randomized to three groups (n = 15 each) for double-blind study. After a test dose into the epidural space at T5-7 (groups T-A and T-AL) or L2-3 (group L-A) interspace, 10 micrograms/Kg of alfentanil was administered in all groups, followed by epidural infusion of 400 micrograms/h of alfentanil (group T-A and L-A) or 400 micrograms/h of alfentanil with 50 mg/h of lidocaine (group T-AL) during surgery and 24 hours postoperatively. The patients also used a patient-controlled analgesia device to administer intravenous morphine postoperatively. During the study period the following variables were recorded: hemodynamic parameters, lung function, quality of analgesia and respiratory complications. ANOVA was performed and Scheffé and Chi-square tests were applied with 0.05 as the level of statistical significance. RESULTS: No differences were found between groups with respect to patient characteristics or type of surgery. Rescue analgesia requirements were higher in group L-A than in the other groups. PaO2 (6 and 18 hours) and spirometric parameters (12 and 18 hours) were significantly higher in group T-AL than in the other groups (p < or = 0.05). No other statistically significant differences were found. CONCLUSIONS: Respiratory parameters were better after thoracic epidural analgesia with alfentanil and lidocaine than after the other analgesic techniques studied. Group L-A patients had greater need for rescue analgesia than did patients in the other groups.

[Fastrach laryngeal mask, sevoflurane and remifentanil: an anesthetic alternative for the myasthenic patient]. / Mascarilla laríngea Fastrach, sevoflurano y remifentanilo: una alternativa anestésica del paciente miasténico.

A 46-year-old myasthenic man diagnosed two months earlier and experiencing nocturnal dyspnea was scheduled for transsternal thymectomy. The patient was premedicated with midazolam in the operating room. Anesthetic induction and maintenance were with inhaled sevoflurane and an intravenous infusion of remifentanil, with no need for neuromuscular relaxants. Airway management was achieved by inserting a Fastrach laryngeal mask (LM-Fastrach), through which an endotracheal tube could be inserted easily. The tube was withdrawn through the mask at the end of surgery and the mask was removed in the operating room 6 minutes later. Anesthesia in patients with myasthenia gravis is one of the greatest challenges in clinical anesthesiology. The interest of this case lies mainly in that the anesthetic technique chosen allows neuromuscular relaxants to be avoided. Moreover, airway access through the Fastrach laryngeal mask is highly useful for transsternal thymectomy of the patient with myasthenia gravis, providing immobility and adequate hemodynamic stability during sternotomy as well as facilitating safe and rapid postanesthetic recovery.

[Lung function and quality of analgesia after lung resection with epidural alfentanyl]. / Función pulmonar y calidad de la analgesia tras cirugía resectiva pulmonar con alfentanilo epidural.

OBJECTIVES: To evaluate the effects on postoperative pulmonary function and quality of analgesia of two protocols for epidural infusion of alfentanil after lung resection. PATIENTS AND METHODS: After informed consent, 30 ASA I-IV patients undergoing chest surgery (lobectomy or pneumonectomy) were randomly assigned to two groups of 15. A catheter was inserted into the epidural space at T5-7 (group T) or L2-3 (group L). After a test dose, an initial bolus of alfentanil (10 micrograms/kg) was administered. After anesthetic induction, epidural analgesia was performed with an infusion of 400 micrograms/h of alfentanil (group L) during and after surgery. Endovenous patent-controlled anesthesia (PCA) was provided with morphine. During the first 24 h after surgery, the following variables were recorded: arterial blood gas concentrations, spirometric parameters, pain on a visual analog scale (VAS) and side effects. ANOVA and Scheffé and chi-square tests were used to analyze the results (p < or = 0.05). RESULTS: In group T, PaO2 was significantly higher at 6 and 18 h (p < or = 0.05), while FEV1 and FVC were significantly higher at 12 and 18 h. Pain assessed by VAS and PCA need for morphine was significantly less in group T. CONCLUSIONS: Thoracic epidural analgesia with alfentanil and lidocaine improves postoperative lung function and reduces the need for top-up analgesia in comparison with lumbar epidural infusion of alfentanil.

[Comparative study of preemptive and postincisional lumbar epidural morphine in pulmonary resection. Preliminary report]. / Estudio comparativo entre morfina epidural lumbar preventiva o postincisional en cirugía resectiva pulmonar. Informe preliminar.

OBJECTIVES: To evaluate the efficacy and incidence of side effects of two types of lumbar epidural analgesia with morphine, preemptive or postincisional, combined with total intravenous anesthesia in chest surgery. PATIENTS AND METHODS: This double-blind prospective study enrolled 20 patients (ASA I-IV) undergoing lobectomy or pneumonectomy. Anesthetic induction and maintenance was provided with propofol, atracurium and alfentanil. Lumbar epidural analgesia (L2-L3) with morphine was provided for group A patients with 2 to 4 mg upon excision of tissue and for group B with 2 to 4 mg during anesthetic induction. The following variables were recorded: arterial blood gas concentrations, heart rate, SpO2, EtCO2, postanesthetic recovery, arterial gases, side effects and pain on a visual analogue scale. Top-up analgesia was provided by intravenous metamizole and/or epidural morphine. For statistical analysis we used ANOVA, chi-square tests and Student-Newman-Keuls tests. RESULTS: The need for propofol and alfentanil during anesthesia, and for morphine and metamizole after surgery were statistically greater in group A. Pain 18 hours after surgery was also greater in group A. No significant differences between groups for other variables was observed. CONCLUSIONS: Preemptive analgesia with lumbar epidural morphine in addition to the general anesthesia described here seems to provide higher-quality analgesia with few side effects, reducing the need for propofol and alfentanil during surgery and for postoperative morphine and metamizole.

[Effect of the inhalation ++ anesthetic isoflurane on heart electrophysiology]. / Efecto del anestésico inhalatorio isoflurano sobre la electrofisiología cardíaca.

In two groups, A and B, both composed of 10 mongrel dogs, we studied the cardiac electrophysiologic effects of 1 and 1.5 MAC isoflurane administered by liquid injection in a closed circuit. In group B the study was done under pharmacological autonomic blockade (AB). With electrode catheters for programmed pacing and endocavitary potential recordings, we determined during the anesthesia with 1 and 1.5 MAC isoflurane: RR, spontaneous and paced AH, and HV intervals, corrected sinus recovery time (CSRT), Wenckebach point (WP), functional and effective refractory periods of atria (AFRP, AERP) and AV node (AVNFRP, AVNERP), and ventricular effective refractory period (VERP), these were compared to the ones obtained with a previous thiopental control. In group A, 1 MAC isoflurane increased over control: AERP and AH interval (p < 0.05), AFRP (p < 0.005), RR and AH paced intervals, WP, AVNFRP and VERP (p < 0.001), adding to these CSRT (p < 0.01) in 1.5 CAM. This level did not show differences with 1 MAC. In group B, 1 MAC isoflurane increased over control: AH (p < 0.05), RR, paced AH intervals, WP and AVNFRP (p < 0.001), adding to these AFRP and AERP (p < 0.05) in 1.5 MAC. This level increased with regard to 1 MAC: AFRP, AERP, AH paced interval and AVNERP (p < 0.05), and AVNFRP (p < 0.005). Isoflurane alone or with AB increased parameters of sinusal automaticity, atrial refractoriness, AV nodal conduction and refractoriness, increasing only without AB ventricular refractoriness and CSRT. With AB atrial and AV nodal refractoriness increased in an anesthetic depth dependent way.