[Effects of precurarization on oxygen arterial saturation measure with pulse oximetry and neuromuscular function]. / Efectos de la precurarización sobre la saturación arterial de oxígeno medida por pulsioximetría y la función neuromuscular.

OBJECTIVE: To study changes in arterial oxygen saturation (SpO2) measured by pulse oximetry, and the effect of neuromuscular function after precurarization with different nondepolarizing muscle relaxants. PATIENTS AND METHOD: One hundred twenty-four patients scheduled for elective surgery were randomly assigned to four groups according to the NDPMR received: d-tubocurarine 0.05 mg/kg, atracurium 0.05 mg/kg, vecuronium 0.01 mg/kg or pancuronium 0.015 mg/kg. We recorded SpO2 before precurarization and 4 minutes after administering the dose. We also recorded signs and symptoms of muscle weakness after the 4-minute period of precurarization. RESULTS: We observed a statistically significant decrease in SpO2 4 minutes after starting precurarization in the groups receiving pancuronium, vecuronium and atracurium. These three groups were also significantly different from the d-tubocurarine group with regard to signs and symptoms of muscle weakness; the incidences of such symptoms were similar among the three groups, the only exception being the greater difficulty patients in the pancuronium group had in maintaining the Valsalva maneuver for 10 seconds. The lowest incidence of clinical signs of muscle weakness were in the d-tubocurarine group. We found a significant relation between decreased SpO2 caused by precurarization and the variables of inability to maintain the Valsalva maneuver for 10 seconds and to raise the head for more than 4 seconds. CONCLUSIONS: SpO2 measured by pulse oximetry is an effective method for monitoring breathing function in the precurarized patient, as it detects early changes in arterial oxygen saturation related to respiratory muscle weakness. The agent d-tubocurarine is recommended for precurarization, because of its scarce effect on neuromuscular function at the dose used in this study.

[Bibliometric analysis of the original articles published in the Revista Española de Anesthesiología y Renimación in 10 years (1987-1996)]. / Análisis bibliométrico de los artículos originales publicados en la Revista Española de Anestesiología y Reanimación durante 10 años (1987-1996).

OBJECTIVE: To describe the original research articles published in Revista Española De Anestesiología y Reanimación (REAR) from 1987 through 1996, as well as to characterize the citations included in those articles. MATERIAL AND METHODS: The 299 articles published as original research in REAR over the past 10 years (1987 through 1996) were analyzed. The bibliographic aspects examined were coauthorship (authors/paper index), citations per article, isolation in function of language of publication of references, degree of obsolescence of articles based on year of references cited ("half-life"), self-citation and degree of dispersion of citations. RESULTS: The authors/paper index was 5.16 +/- 1.62. No statistically significant difference was found in number of authors over the 10-year study period. Mean number of references cited per article was 24.05 +/- 12.02. We found statistically significant differences for 1993 and the period 1987 to 1988, and 1994 and the year 1987 (p < 0.001). The "half-life" of articles was 6 when analyzing on a year-by-year basis; this index ranged from 5.5 to 7, with no significant annual differences. REAR articles accounted for 4.02% of all citations. English was the most frequent language of cited publications, with 6,240 references (86.8%), followed by Spanish with 621 (8.64%), French with 223 (3.1%) and German with 74 (1.03%). Of the 7,191 references analyzed, 6,447 (89.65%) were of scientific journals. Books are the second most commonly cited type of document, with 623 (8.66%) citations. Analyzing journals cited 25 or more times, we found that 74.19% of the articles (4,783/6,447) had been published in 5.3% of the journals (36/678). Seven journals of anesthesia, which represented 1.03% of all journals (7/678) appeared in 52.81% of references of this type (3,405/6,447). CONCLUSIONS: The number of authors of original research articles published in REAR in the last 10 years was high. Spanish authors in anesthesiology cite mainly literature in English; use up-to-date sources of information, mainly journals; and take a large proportion of information from a small number of journals, which are those of greatest international impact in our specialty.

[Bupivacaine in continuous epidural infusion using a portable mechanical devise for postoperative analgesia after surgery for hernia of the lumbar disk]. / Bupivacaína en infusión epidural continua mediante dispositivo mecánico portátil para analgesia postoperatoria de cirugía de la hernia de disco lumbar.

OBJECTIVES: To determine the optimum concentration of bupivacaine administered by continuous epidural infusion, using a Baxter Single Day elastomeric infusor at a rate of 2 ml/h, to treat pain during the first 24 h after lumbar laminectomy. PATIENTS AND METHODS: Sixty patients undergoing elective repair of a herniated lumbar disk were randomly assigned to three homogeneous groups of 20 each. Group I received epidural infusion of 0.0625% bupivacaine, group II received 0.125% bupivacaine and group III received 0.25% bupivacaine. After surgery each patient was given a 4 mL solution of the local anesthetic being studied, followed by an infusion of the same through an elastomeric infusor at a rate of 2 ml/h throughout the first 24 h after surgery. Ketorolac was delivered through a device for patient controlled analgesia after surgery. Pain was assessed on a visual analog scale (VAS) at rest and during movement. Pain relief was assessed on a simple descriptive scale. RESULTS: Significantly less ketorolac was required during epidural infusion of 0.125% and 0.25% bupivacaine than when the 0.0625% concentration was being infused (29 +/- 16 and 28 +/- 13 mg, respectively, versus 110 +/- 35 mg; p < 0.001). VAS scores were significantly lower during infusion of 0.125% and 0.25% bupivacaine than with 0.0625% bupivacaine. No instances of motor blockade or infection related to catheter insertion were observed in any of the patients. CONCLUSIONS: Continuous epidural infusion of 0.125% and 0.25% bupivacaine through an elastomeric infusor gives excellent analgesia during the first 24 h after surgery. Administration of 0.25% bupivacaine is associated with a higher incidence of urinary retention. We therefore think that the most recommendable concentration of bupivacaine for infusion is 0.125%.

[Infiltration of the surgical wound with local anesthetic for postoperative analgesia in patients operated on for lumbar disc herniation. Comparative study of ropivacaine and bupivacaine]. / Infiltración de la herida quirúrgica con anestésico local para analgesia postoperatoria en pacientes intervenidos de hernia de disco lumbar. Estudio comparativo entre ropivacaína y bupivacaína.

OBJECTIVE: To assess and compare the analgesic efficacy of infiltrating the wound with ropivacaine or bupivacaine for postoperative pain after lumbar disk repair. PATIENTS AND METHODS: A prospective, randomized double blind study of 45 patients undergoing elective surgery for herniated lumbar disk repair under general anesthesia. Before the surgical wound was closed, the paraspinal musculature and subcutaneous tissue were infused with 30 ml of 0.25% ropivacaine in group I (n = 15), 30 ml of 0.25% bupivacaine in group II (n = 15) or 30 ml of saline solution in group III (n = 15). Ketorolac for supplementary postoperative analgesia was made available through a patient-controlled intravenous system. We analyzed the degree of pain on a visual analog scale and level of pain relief on a simple descriptive scale. RESULTS: No significant differences in demographic data, duration of surgery or amount of intraoperative fentanyl administered were observed among the groups. Mean time until the first request for analgesia was significantly longer in group II than in either groups I or III (164 +/- 53 min versus 68 +/- 31 and 38 +/- 14 min, respectively). Significantly less ketorolac was used in groups I and II than in group III (58 +/- 20 and 59 +/- 21 mg versus 118 +/- 32 mg). The mean scores on the visual analog scale were similar in all three groups. CONCLUSIONS: In this study, infiltration of the surgical wound with 0.25% bupivacaine or 0.25% ropivacaine was similarly effective for treatment of pain after lumbar disk laminectomy.

[Puerperal cardiomyopathy and pulmonary edema after cesarean section]. / Miocardiopatía periparto y edema pulmonar tras cesárea.

A 26-year-old woman in the thirty-second week of her fifth pregnancy was admitted with diffuse sudden-onset abdominal pain. Examination revealed cervical dilation to 8 cm, a ruptured uterine cerclage and transverse presentation of the fetus, indicating a need for emergency cesarean section, which was performed under uneventful spinal anesthesia. Three days after surgery the patient presented signs consistent with acute pulmonary edema coinciding with blood transfusion. Echocardiography demonstrated left ventricular systolic dysfunction with an ejection fraction of 35%. The diagnosis was peripartum myocardiopathy with acute respiratory insufficiency due to heart failure. Furosemide and captopril were prescribed and the outcome was satisfactory. The discharge echocardiogram showed a left ventricle of normal size and thickness, and the ejection fraction was 55%. Peripartum myocardiopathy is a type of heart failure that develops during the third trimester or during the first six months after delivery, in the absence of signs of ventricular dysfunction or previous heart disease. Based on clinical presentation and echocardiographic findings, we believe that peripartum myocardiopathy was the cause of acute pulmonary edema in this patient.

[Pulse oximetry reduces the unnecessary administration of oxygen in the postanesthesia recovery period]. / La pulsioximetría reduce la administración innecesaria de oxígeno en el período de recuperación postanestésica.

OBJECTIVES: To investigate whether patients admitted to the postanesthesia recovery unit (PRU) need routine oxygen supplementation in the immediate postoperative period, by measuring changes in arterial oxygen saturation (SpO2) with a pulse oximeter. MATERIAL AND METHODS: Two hundred ninety-nine patients were admitted to the PRU after surgery. All breathed room air after their operations. During transfer to and time in the PRU, SpO2 was recorded. We administered oxygen through a face mask to patients whose SpO2 fell below 94% and to patients whose SpO2 levels fell below baseline, when baseline values were less than 94%. We recorded patient data, physical status (ASA), type of anesthesia, duration of surgery, Aldrete score upon admission to the PRU and SpO2 before and after surgery while the patient breathed room air. RESULTS: General anesthesia was used in 82.3% of the patients and local-regional anesthesia with sedation in 17.7%. PRU stay was 75.6 +/- 92.4 min. Twenty-five percent of the patients were treated with oxygen after surgery and 75% did not require supplemental oxygen. Time until the appearance of desaturation was 3.3 +/- 2.8 min. The coefficient of multiple correlation between postoperative SpO2 while breathing room air (dependent variable) and preoperative SpO2, age and duration of surgery was R = 0.522 (p < 0.001). CONCLUSIONS: Our results are sufficient to demonstrate the validity of pulse oximetry for avoiding indiscriminate oxygen supplementation in patients admitted to the PRU.

[Postoperative analgesia with epidural methadone in patients operated for hernia of the lumbar disc]. / Analgesia postoperatoria con metadona epidural en pacientes intervenidos de hernia de disco lumbar.

OBJECTIVES: To determine whether the direct application of a single dose of methadone on the dura mater at the end of surgery to repair a lumbar disk hernia provides effective analgesia over the next 24 hours. PATIENTS AND METHODS: We conducted a randomized double blind study in 40 ASA I patients undergoing elective herniated disk repair under general anesthesia. The sample was divided into two groups (A and B). Group A patients received a solution of methadone in saline solution (5 mg methadone/5 ml saline) applied to the dura before the end of surgery. Group B patients (controls) received only 5 ml of saline. Pain intensity was assessed on a visual analog scale (VAS) during the postoperative period. Also recorded were the observer's impression and the amount of analgesia (ketorolac) consumed through a system providing patient controlled analgesia. RESULTS: Each group contained 20 patients. Group A patients needed significantly less postoperative analgesia (64.2 +/- 14.3 mg) than group B patients (109.6 +/- 16.5 mg). The VAS scores were significantly lower in group A during the first two hours after surgery and were correlated with the observer's impression. No patients suffered serious complications during the study. CONCLUSIONS: Topical administration of 5 mg of methadone on the dura mater at the end of herniated lumbar disk repair is an easy, safe and effective technique for providing postoperative analgesia.

[Intravenous anesthesia with propofol in intracranial surgery]. / Anestesia intravenosa con propofol en la cirugía intracraneal.

OBJECTIVES: To analyze the repercussions of intravenous anesthesia with propofol as the single hypnotic drug on intracranial pressure (ICP) and cerebral perfusion pressure (CPP), and also to study the time until recovery from anesthesia and to tracheal extubation as well as intraoperative hemodynamic changes in patients undergoing surgery to remove a supratentorial brain tumor. PATIENTS AND METHODS: Twenty-three ASA I/II patients scheduled for exeresis of a supratentorial brain tumor were studied. A fiberoptic sensor placed in direct contact with the dura mater was used to measure ICP. Anesthetic induction was achieved with propofol (2 mg/kg). Propofol (12 and 9 mg/kg/h for 10 min and 6 mg/kg/h throughout the rest of the operation) was used for maintenance. Mean arterial pressure (MAP), heart rate (HR), ICP and CPP were recorded at baseline and 1, 2, 3 and 4 min after induction, during laryngoscopy and tracheal intubation; 1, 3, 5, 10, 15 and 20 min after tracheal intubation (L + 1, L + 3, L + 5, L + 10, L + 15, L + 20), upon placement of a craniostat; upon skin incision; upon withdrawal of propofol perfusion; and during extubation. The following variables were recorded after awakening: time until eye opening after receiving a verbal command, time until extubation and time until orientation. Analysis of variance for repeated measures (ANOVA) was performed on the results. RESULTS: MAP decreased significantly from baseline at the following times: during the post-induction period, upon placement of the craniostat, upon skin incision and when the propofol infusion was switched off. HR increased significantly during laryngoscopy and at the following moments: intubation, post intubation (L + 1, L + 3, L + 5), craniostat placement, and extubation. ICP was lower throughout the surgical period except during laryngoscopy, when this variable increased significantly. CPP decreased significantly after induction and returned to baseline after intubation. CPP was significantly higher after surgery. Recovery times after weaning from propofol infusion until eye opening in response to an order and until orientation were 13 +/- 3 and 22 +/- 4 min, respectively. The mean interval between withdrawal of propofol until extubation was 18 min. CONCLUSIONS: Intravenous anesthesia with propofol in intracranial surgery (supratentorial tumors) affords hemodynamic stability and lowers ICP except during laryngoscopy. Early recovery from anesthesia allows for neurological assessment and vigilance during the immediate postoperative period.

[Environmental and biological control in a population exposed to isoflurane in the operating room]. / Control ambiental y biológico de una población expuesta a isoflurano en el quirófano.

OBJECTIVE: To measure the level of occupational exposure to isoflurane in the operating room, and to determine the relation between isoflurane concentration in atmospheric and exhaled air. PATIENTS AND METHODS: One hundred seventy-eight samples were obtained from 60 male and female subjects who work in the operating room of our hospital. To monitor workplace exposure we used passive diffusion samplers. Biological monitoring (isoflurane in exhaled air) was accomplished with standard adsorption tubes to collect exhaled air samples. Gases were thermically separated and analyzed by gas chromatography. RESULTS: Atmospheric isoflurane concentrations ranged between 1.14 and 157.23 mg/m3 (geometric mean 16.23 mg/m3). Exhaled isoflurane concentrations ranged from 0.15 to 26.09 mg/m3 (geometric mean 2.85 mg/m3). Atmospheric and exhaled isoflurane concentrations were strongly related (r = 0.82; p < 0.0001). Linearity was determined by the following equation: log of exhaled isoflurane concentration = -0.69 + 0.95 log of atmospheric isoflurane concentration. CONCLUSIONS: The concentrations of isoflurane in atmospheric and exhaled air found in our study exceed the maximum levels for halogenated gases recommended by the National Institute for Occupational Safety and Health, although they do not exceed the levels stipulated by Swiss authorities. In order to adequately assess operating room antipollution measures, atmospheric and biologic monitoring of isoflurane and other inhaled anesthetic gas concentrations is necessary.

[Cardiovascular response to tracheal intubation in patients with intracranial tumor. Comparative study between urapidil and lidocaine]. / Respuesta cardiovascular a la intubación traqueal en pacientes con tumor intracraneal. Estudio comparativo entre el urapidilo y la lidocaína.

OBJECTIVES: To compare the effects of urapidil and lidocaine on cardiovascular response to laryngoscopy and tracheal intubation in patients with brain tumors. PATIENTS AND METHODS: Prospective, randomized double-blind study of 40 ASA II-III patients undergoing elective surgery for supratentorial tumor resection. The patients were assigned to two groups of 20 to receive an intravenous bolus of 1.5 mg/kg of lidocaine or 0.4 mg/kg urapidil before laryngoscopy and intubation. Anesthetic induction was performed with 0.03 mg/kg midazolam, 3 micrograms/kg of fentanyl, 5 mg/kg of thiopental and 0.2 mg/kg of vecuronium. Anesthesia was maintained with N2O/O2 (60%/40%) and isoflurane (0.5% expired). The following variables were recorded: mean blood pressure, heart rate and arterial oxygen saturation (SpO2) at baseline and 1, 2 and 3 min after induction and at 1, 2, 3, 4, 5 and 10 min after laryngoscopy and tracheal intubation. RESULTS: The two groups were comparable with respect to age, sex, weight, height and baseline hemodynamics. No statistically significant differences in hemodynamic variables were found between the two groups. Mean blood pressure in the postintubation period stayed near baseline and heart rate increased significantly after laryngoscopy and tracheal intubation in both groups. SpO2 decreased 7 min after administration of urapidil and stayed lower throughout the study period and was statistically different from SpO2 in the lidocaine group. All changes described were within clinically normal ranges. CONCLUSIONS: In patients undergoing neurosurgery to remove a supratentorial tumor, both lidocaine and urapidil reduce the pressor response to laryngoscopy and tracheal intubation at the doses given in this study. However, neither was able to prevent the increase in heart rate.

[Pressure pneumocephalus after posterior fossa surgery in the sitting position]. / Neumoencéfalo a tensión tras cirugía de la fosa posterior en sedestación.

Pneumocephalus occurs commonly soon after intracranial surgery. When it presents as a significant increase in intracranial pressure it is called pressure pneumocephalus, a severe, life-threatening complication of neurosurgery that requires immediate treatment. Tension pneumocephalus must be suspected in patients unexpectedly fail to awaken at the end of surgery or who present progressive neurological deterioration after posterior fossa surgery. Diagnosis is by computerized axial thomography of the brain. Treatment is simple, consisting of promptly releasing the pressurized gas by trephination to save the patient's life or prevent severe neurological sequelae. We report two cases of pressure pneumocephalus that illustrate several risk factors: sitting position during surgery, preoperative hydrocephaly, surgical opening of the fourth ventricular and the presence of cerebrospinal shunt during surgery.

Miocardiopatía periparto y edema pulmonar tras cesárea / Peripartum cardiomyopathy and pulmonary edema after cesarean delivery

Una mujer de 26 años, en la semana 32 de su quinta gestación, ingresó por dolor abdominal difuso de instauración brusca. En la exploración se objetivó una dilatación de 8 cm del cuello uterino, rotura del cerclaje uterino y presentación transversa del feto, por lo que se indicó cesárea urgente, que se realizó bajo anestesia subaracnoidea sin incidencias. Al tercer día del postoperatorio la paciente inició un cuadro compatible con edema agudo de pulmón coincidiendo con la administración de sangre. Se le realizó una ecocardiografía que mostró una disfunción sistólica global del ventrículo izquierdo con fracción de eyección del 35 por ciento, y se diagnosticó de miocardiopatía periparto, con insuficiencia respiratoria aguda por insuficiencia cardíaca. Se trató con furosemida y captopril y la evolución fue favorable. Al alta hospitalaria, la ecocardiografía mostró un ventrículo izquierdo de tamaño y espesor normal y fracción de eyección del 55 por ciento. La miocardiopatía periparto es un modo de insuficiencia cardíaca que se produce en el último trimestre de embarazo o durante los seis primeros meses del puerperio, en ausencia de una causa demostrable de disfunción ventricular y de enfermedad cardíaca previa. De acuerdo con la presentación clínica y con los hallazgos ecocardiográficos encontrados en esta paciente, consideramos que la miocardiopatía periparto fue la causa del edema agudo de pulmón (AU)

Edema pulmonar unilateral porreexpansión tras exéresis de una masamediastínica de gran tamaño / Unilateral pulmonary edema due to reexpansion after exeresis of a large mediastinal

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