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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[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.

La pulsioximetría reduce la administración innecesaria de oxígeno en el período de recuperación postanestésica / Pulse oximetry reduces unnecessary oxygen administration during recovery from anesthesia

Objetivos: Investigar si los pacientes ingresados en la Unidad de Recuperación Postanestésica (URPA) necesitan O2 suplementario de rutina en el postoperatorio inmediato, midiendo las variaciones saturación arterial de oxígeno (SpO2) mediante la pulsioximetría. Material y Métodos: Se incluyó a 299 pacientes intervenidos y que asistimos en la URPA una vez finalizada la cirugía. Todos los pacientes respiraban aire ambiente después de haber sido intervenidos. Durante el traslado y permanencia en la URPA se registró SpO2. Administramos O2 mediante mascarilla en los casos de SpO2 < 94 por ciento y en aquellos pacientes con valores de SpO2 inferiores a los basales, cuando éstos eran < 94 por ciento. Durante el estudio se registraron: datos demográficos, estado físico ASA, tipo de anestesia, duración de la intervención, puntuación de la aplicación del test de Aldrete en el momento del ingreso en la URPA y SpO2 pre y postoperatoria respirando aire ambiente. Resultados: La anestesia general se utilizó en el 82,3 por ciento de los pacientes, siendo la técnica lo corregional con sedación en el 17,7 por ciento. El tiempo de estancia en la URPA fue de 75,6 ñ 92,4 min. El 25 por ciento de los pacientes fueron tratados con O2 en el postoperatorio frente al 75 por ciento que no precisaron O2 suplementario. El intervalo de tiempo de la aparición de la desaturación fue de 3,3 ñ 2,8 min. El coeficiente de correlación múltiple entre la SpO2 postoperatoria respirando aire ambiente (variable dependiente) y las variables SpO2 preoperatoria, edad y duración de la intervención fue R = 0,522 (p < 0,001).Conclusiones: Nuestros resultados prueban suficientemente la validez de la pulsioximetría en los pacientes ingresados en la URPA toda vez que evita el uso indiscriminado de O2 en dicha unidad. (AU)

[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.

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)

Shock anafilático por hidatidosis en el postoperatorio inmediato / Anaphylactic shock of hydatidosis during recovery from surgery

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[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.

[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%.

Bupivacaína en infusión epidural continua mediante dispositivo mecánico portátil para analgesia postoperatoria de cirugía de la hernia de disco lumbar / Continuous epidural infusion of bupivacaine through a portable mechanical device for postoperative analgesia after lumbar laminectomy

OBJETIVOS. Determinar la concentración óptima de bupivacaína administrada mediante infusión epidural continua, utilizando un infusor elastómero modelo Baxter Single Day infusor 2 ml/h®, para el tratamiento del dolor en las primeras 24 h del postoperatorio tras la cirugía de la hernia de disco lumbar. PACIENTES Y MÉTODOS. Se estudian 60 pacientes sometidos a cirugía electiva por hernia de disco lumbar bajo anestesia general. Los pacientes fueron distribuidos aleatoriamente en tres grupos homogéneos de 20 individuos cada uno de ellos: grupo I, perfusión epidural de bupivacaína al 0,0625 por ciento; grupo II, bupivacaína al 0,125 por ciento, y grupo III, bupivacaína al 0,25 por ciento. Al finalizar la cirugía, a cada paciente se le administraron 4 ml de la solución anestésica local que se iba a estudiar, seguida de una infusión de la misma por medio de un infusor elastómero con una tasa de infusión de 2 ml/h durante las primeras 24 h del postoperatorio. Se pautó analgesia postoperatoria por medio de un sistema de analgesia intravenosa controlada por el paciente (PCA) de ketorolaco. Se analizó el grado de dolor mediante la escala analógica visual (EAV) en reposo y durante la movilización, y el alivio del dolor utilizando una escala descriptiva simple. RESULTADOS. Los requerimientos de ketorolaco fueron significativamente menores durante la perfusión epidural de bupivacaína al 0,125 por ciento y al 0,25 por ciento que cuando se administró bupivacaína al 0,0625 por ciento (29 ñ 16 y 28 ñ 13 mg frente a 110 ñ 35 mg; p < 0,001). Las puntuaciones del dolor fueron significativamente inferiores durante la perfusión de bupivacaína al 0,125 por ciento y al 0,25 por ciento frente a la perfusión de bupivacaína al 0,0625 por ciento. No se observó bloqueo motor en ninguno de los pacientes estudiados ni infección en el emplazamiento del catéter. CONCLUSIONES. La perfusión epidural continua por medio de un infusor elastómero de bupivacaína al 0,125 por ciento y bupivacaína al 0,25 por ciento proporcionaron una excelente analgesia durante las primeras 24 h del postoperatorio, asociándose a la administración de bupivacaína al 0,25 por ciento una mayor incidencia de retención urinaria, por lo que consideramos que la pauta más recomendable es la infusión de bupivacaína al 0,125 por ciento (AU)

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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 / Infiltration of the surgical wound with local anesthetic for postoperative analgesia after herniated lumbar disk repair. Comparison of ropivacaine and bupivacaine

OBJETIVOS. Valorar y comparar la efectividad analgésica de la infiltración de la herida quirúrgica al final de la cirugía de la hernia de disco lumbar con ropivacaína y bupivacaína en el tratamiento del dolor postoperatorio.PACIENTES Y MÉTODOS. Estudio prospectivo, aleatorio y doble ciego de 45 pacientes sometidos a cirugía electiva por hernia de disco lumbar bajo anestesia general. Antes del cierre quirúrgico, se realizó la infiltración de la musculatura paraespinal y del tejido subcutáneo con 30 ml de ropivacaína al 0,25 por ciento a los pacientes del grupo I (n = 15), con 30 ml de bupivacaína al 0,25 por ciento a los pacientes del grupo II (n = 15), y con 30 ml de suero salino a los pacientes del grupo III (n = 15). Se pautó analgesia suplementaria en el postoperatorio por medio de un sistema de analgesia intravenosa controlada por el paciente con ketorolaco. Analizamos el grado de dolor por medio de la escala analógica visual y el alivio del dolor utilizando una escala descriptiva simple.RESULTADOS. No hubo diferencias en los datos demográficos, la duración de la intervención y la cantidad de fentanilo intraoperatoria administrado. El tiempo medio del primer requerimiento de analgesia fue significativamente mayor en el grupo II respecto a los grupos I y III (164 ñ 53 min frente a 68 ñ 31 y 38 ñ 14 min). El consumo de ketorolaco fue significativamente menor en los grupos I y II durante el estudio que en el grupo III (58 ñ 20 y 59 ñ 21 mg frente a 118 ñ 32 mg). La puntuación de la escala analógica visual fue similar en los tres grupos estudiados.CONCLUSIONES. En nuestro trabajo las infiltraciones de la incisión quirúrgica con bupivacaína al 0,25 por ciento y con ropivacaína al 0,25 por ciento tuvieron una eficacia semejante para el tratamiento del dolor tras discectomía lumbar (AU)

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[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.

Respuesta cardiovascular a la intubación traqueal en pacientes con tumor intracraneal. Estudio comparativo entre el urapidilo y la lidocaína / Cardiovascular response to tracheal intubation in patients with an intracranial tumor. Comparison of urapil and lidocaine

Objetivos. Comparar los efectos del urapidilo y la lidocaína sobre la respuesta cardiovascular a la laringoscopia e intubación traqueal en pacientes con tumores cerebrales. Pacientes y métodos. Estudio prospectivo, aleatorio y doble ciego sobre 40 pacientes ASA II/III, intervenidos electivamente para resección de tumor supratentorial. Los pacientes fueron distribuidos en dos grupos de 20 pacientes cada uno para recibir un bolo intravenoso de 1,5 mg/kg de lidocaína o de 0,4 mg/kg de urapidilo antes de la laringoscopia e intubación. La inducción de la anestesia se realizó con 0,03 mg/kg de midazolam, 3 µg/ kg de fentanilo, 5 mg/kg de tiopental y 0,2 mg/kg de vecuronio. El mantenimiento anestésico se consiguió con N2O/O2 (60/40 por ciento) e isoflurano (0,5 por ciento espirado). Se registraron los siguientes parámetros: presión arterial media, frecuencia cardíaca y saturación arterial de oxígeno basales, 1, 2, y 3 min postinducción, y 1, 2, 3, 4, 5 y 10 min después de la laringoscopia e intubación traqueal. Resultados. Los dos grupos fueron homogéneos en cuanto a edad, sexo, peso, talla, y datos hemodinámicos basales. No se observaron diferencias estadísticamente significativas en los valores hemodinámicos registrados durante el estudio entre los dos grupos. La presión arterial media en el período postintubación estuvo próxima al valor basal y la frecuencia cardíaca aumentó significativamente tras la laringoscopia e intubación traqueal, en ambos grupos. La SpO2 disminuyó a los 7 min de la administración del urapidilo y durante todo el período de estudio, con diferencias estadísticamente significativas frente al grupo lidocaína. Todos los cambios descritos fueron dentro de valores clínicamente normales. Conclusiones. A las dosis administradas, tanto la lidocaína como el urapidilo, atenuaron la respuesta presora a la laringoscopia e intubación traqueal en pacientes neuroquirúrgicos con tumor supratentorial, pero no pudieron evitar el aumento de la frecuencia cardíaca (AU)

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[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.

[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.

[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.

[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.