Volume guarantee ventilation during surgical closure of patent ductus arteriosus.

BACKGROUND: Surgical closure of patent ductus arteriosus (PDA) is associated with adverse outcomes. Surgical exposure requires retraction of the lung, resulting in decreased aeration and compliance. Optimal respiratory support for PDA surgery is unknown. Experience with volume guarantee (VG) ventilation at our institution led us to hypothesize that surgery would be better tolerated with automatic adjustment of pressure by VG to maintain tidal volume (VT) during retraction. OBJECTIVE: The objective of this study was to describe ventilator support, VT, and oxygenation of infants supported with VG during PDA surgery. DESIGN/METHODS: Ventilator variables, oxygen saturation, and heart rate were recorded during PDA surgery in a convenience sample of infants during PDA closure on VG. Pressure limit increased 11% and set VT was 26% lower during lung retraction. Fentanyl and pancuronium/vecuronium were used for anesthesia/muscle relaxation. Longitudinal data were analyzed by analysis of variance for repeated measures. RESULTS: Seven infants, 25.4 ± 1.5 weeks and 723 ± 141 g, underwent closure of PDA on VG at a mean age 29.9 days. No air leak, bradycardia, or death occurred. Target VT was maintained with a modest increase in inflation pressure. Oxygenation remained adequate. CONCLUSIONS: VG avoided hypoxemia and maintained adequate VT with only a modest increase in peak inflation pressure and thus may be a useful mode during PDA surgery.

Off-pump coronary artery bypass grafting: a case report.

It is easy to take for granted the seemingly effortless way cardiovascular surgeons are able to bypass atherosclerotic coronary arteries. The process used today was developed over many years of rigorous study, experimentation, success, and failure. Early cardiac surgery was performed blindly, through small incisions, on a beating heart. Advances in medicine allowed surgery to be performed on hearts stilled by cardioplegic arrest, while the circulation was continued through the use of a cardiopulmonary bypass (CPB) machine. The development of the CPB machine allowed surgeons to perform the delicate work of coronary artery bypass grafting (CABG), first attempted on dogs, and then humans. This article briefly outlines the historical evolution of cardiac surgery that led to the development of the technology necessary to perform off-pump coronary artery bypass grafting (OPCAB). A case report of a 72-year-old female who underwent OPCAB is outlined. Included is a discussion of some of the benefits and potential complications of CABG and OPCAB. Anesthetic considerations for OPCAB procedures also are presented.

Midlatency auditory-evoked potentials in the assessment of sedation in cardiac surgery patients.

OBJECTIVES: Midlatency auditory-evoked potentials (MLAEPs) may provide an objective measure of depth of sedation. The aim of this study was to evaluate MLAEPs for measuring sedation in cardiac surgery patients. DESIGN: Prospective study. SETTING: Intensive care unit of a university hospital. PARTICIPANTS: Twenty-two patients scheduled for elective coronary artery bypass grafting. INTERVENTIONS: MLAEPs were obtained at 5 time points: the day before surgery (baseline), 1 hour before surgery, after premedication, postoperatively during deep (Ramsay 6) and moderate (Ramsay 4) sedation, and the day after surgery. MEASUREMENTS AND MAIN RESULTS: The latency of the Nb MLAEP component increased from 44 ms (38-60 ms; median, range) at baseline to 49 ms (41-64 ms) after premedication (p = 0.03) and further to 63 ms (48-80 ms) during deep sedation after surgery (P < 0.01). Although a decreasing clinical level of sedation after rewarming was not associated with a significant change in Nb latency (61 ms [42-78 ms]), the MLAEP NaPa amplitude increased from 0.9 muV (0.4-1.6 microV) to 1.3 muV (0.8-3.9 microV; p = 0.01). Nb latency remained increased the day after surgery (49 ms [37-71 ms]) as compared with baseline (p < 0.01). CONCLUSIONS: MLAEP latencies can reflect subtle changes in auditory perception, while amplitudes seem to change with transition between deep levels of sedation.

Quantitative assessment of tracheal collapsibility in infants with tracheomalacia.

Infantile tracheomalacia is a potentially life-threatening disease requiring prolonged artificial respiratory support. Diagnosis and management of this disease may be further improved by establishing a suitable objective and quantitative assessment protocol for tracheal collapsibility. It is our hypothesis that tracheal collapsibility can be represented by the relationship between intraluminal pressure and the cross-sectional area of the trachea. To test this hypothesis, static pressure/area relationships of the trachea were obtained from anesthetized and paralyzed infants, who were diagnosed as having tracheomalacia by endoscopic observation. These relationships were fitted on a linear regression model, followed by calculation of the estimated closing pressure. The tracheal closing pressure ranged from -8 to -27 cm H(2)O, suggesting easy collapsibility of the trachea during crying or coughing and noncollapsibility during the spontaneous respiratory cycle, which coincided with the infants' symptoms. It is our conclusion that tracheal collapsibility of infants with tracheomalacia can be quantitatively assessed by the static pressure/area relationship of the trachea obtained under general anesthesia and paralysis.

Effect of pipecuronium and pancuronium on intracranial pressure and cardiovascular parameters in patients with supratentorial tumours.

A prospective, randomised, single blind study was conducted to evaluate and compare the intracranial pressure (ICP) and cardiovascular effects of pipecuronium (PPC) and pancuronium (PNC) in 20 patients undergoing supratentorial surgery. Patients were randomly divided into two groups. Patients in Group I (n = 10) received pancuronium (0.1 mg kg(-1)) and in Group II (n = 10) pipecuronium (0.07 mg kg(-1)) for intubation. Intracranial pressure (ICP), heart rate (HR), systolic, diastolic and mean arterial pressures (SAP, DAP, MAP), central venous pressure (CVP), nasopharyngeal temperature and arterial blood gases (ABG) were monitored at the following time periods: before induction (0 minutes); 3 minutes after thiopentone and muscle relaxant; immediately after intubation; and 4, 6, 8, 10, 20 and 30 minutes following intubation. The rise in intracranial pressure at intubation was significantly greater in group I (21.10+/-3.97 torr, 122.59%) when compared to group II patients (1.80+/-0.70 torr, 10.04%) (p<0.0 1). Cardiovascular parameters also showed a significantly greater degree of rise in group I when compared to group II patients. Heart rate increased by 29+/-6.32 beats min(-1) (33.52%) and systolic arterial pressure by 11.60+/-7.37 torr (9.47%) in group I. These parameters did not change significantly in group II. No significant alterations were observed in the other measured parameters in either of the two groups.

Eficacia clínica de la relación neuromuscular del vecuronio: una comparación con pancuronio

Con el objetivo de comparar la eficacia clínica del vecuronio respecto al pancuronio, se realizó un estudio de tipo descriptivo, prospectivo y longitudinal, en una serie de 40 pacientes sometidos a cirugía bajo anestesia general y que fueron dividos al azar en 4 grupos de 10 pacientes cada uno, según recibieron relajación con: pancuronio a 0.08 mg/kg, pancuronio a 0.1 mg/kg,vecuronio a 0.1 mg/kg. Se monitorizó la relajación muscular con vigilancia de larazón del tren de cuatro (T4/T1). Resultados: las condiciones de intubación conambos relajantes se relacionó directamente con las dósis empleadas, siendo mejorcon vecuronio a 0.1 mg/kg, donde el 90 por ciento de pacientes tuvo excelentes condiciones, lo cual fue del 70 por ciento con pancuronio a 0.08 mg/kg. La intubación existosa se logró en menor tiempo con ambos relajantes a la dosis de 0.1 mg/kg con 90 por ciento de pacientes entubados antes de 2 minutos. La duración de la relajación fue menor con elvecuronio a ambas dosis respecto al pancuronio, donde el 100 por ciento y 90 por ciento de pacientescon vecuronio 0.08 mg/kg y 0.1 mg/kg respecativamente tuvieron tiempo de relajación menor de 40 minutos. El grupo que necesitó menos reversión farmacológica fue el de vecuronio a 0.08 mg/kg con 40 por ciento de pacientes. Se presentó taquicardia en 70 por ciento y 80 por ciento de pacientes con pancuronio, en tanto que vecuronio la frecuencia cardíaca fue normal en 60 por ciento y 80 por ciento . El 90 por ciento de pacientes con vecuronio mostró presión arterial normal durante la intubación. Las reaciones adversas se dieron en 30 por ciento decasos con las dósis más bajas hasta el 70 por ciento con las dósis más altas. Conclusiones: el vecuronio a 0.1 mg/kg demostró lograr adecuadas condiciones de intubación, con tiempo de intubación intermedio y mejor predictibilidad del tiempo de relajación, así como mejores condiciones hemodinámicas. La bradicardia transquirúrgicafue la principal reacción adversa encontrada con dicha dósis. Las necesidades dereversión fueron similares a las del pancuronio. No se encontró mayores ventajascon el uso de vecuronio a 0.08 mg/kg, excepto por una menor necesidad de reversión farmacológica

Tetanic fade induced by d-Tubocurarine, Hexamethonium and Neostigmine in phrenic nerve diaphragm rats

A acetilcolina liberada do terminal nervoso motor (TNM) pode modular sua pr6pria liberagdo (automodulação do TNM), interagindo com receptores nicotinicos (autoestimulação do TNM) ou muscarinicos (autoinibição do TNM) pré-juncionais. Por outro lado, tem-se demonstrado que a neuropatia induzida pelo estado diabético determine vários danos estruturais no interior do TNM, sem, contudo, interferir na velocidade e na integridade da transmissão neuromuscular. Estudos farmacológicos demonstram que animais diabéticos, quando comparados aos normais, são menos sensíveis a alguns bloqueadores neuromusculares (d-tubocurarina, galamina, pancurônio e decametônio). Esses resultados sugerem que alguma modificação no sistema de automodulação do TNM pode contrabalançar as deficiências neuronais induzidas pelo estado diabético. Dessa forma, o presente estudo foi conduzido com preparações nervo frênico-diafragma isolado de ratos (obtidas de animais normais e diabéticos) na tentativa de verificar se existiriam diferenças na fadiga neuromuscular induzida por drogas (d-tubocurarina, neostigmina, hexametônio). Nossos resultados mostraram que, embora não existissem diferenças na indução da fadiga neuromuscular induzida por d-tubocurarina, neostigmina ou hexametônio, o recobro da fadiga neuromuscular induzida por d-tubocurarina foi mais rápido em preparações neuromusculares obtidas de animais diabéticos. Essa diferença pode estar relacionada a alguma modificação induzida pelo estado diabético que determinou redugio da afinidade da d-tubocurarina para os receptores nicotínicos pré-juncionais

Neuroleptic malignant syndrome in a patient with head injury.

Neuroleptic malignant syndrome is an idiosyncratic reaction associated with the use of neuroleptic drugs. We report a case of this rare syndrome in a head injury patient associated with some unusual features: rhabdomyolysis with a high level of creatine kinase, the development of acute renal failure, the early use of continuous venovenous haemofiltration in treatment and rigidity that was refractory to conventional treatment with dantrolene and bromocriptine. The diagnosis in patients with multiple injuries must be based on a high index of suspicion.

Oxigenación tisular durante la crisis de disautonomía en el tétano severo / Tissular oxygenation during the crisis of dysautonomia in to severe tetanus

El síndrome de hiperactividad simpática en el marco del tétanos severo, es un cuadro de gravedad extrema por ya ser una de las principales causas de muerte. Fisiopatológicamente continúa siendo un "misterio", tratáse de explicar todo lo que ocurre debido a la elevada concentración de catecolaminas circulantes. Sin embargo, poco se sabe sobre el comportamiento de la oxigenación de los tejidos durante las crisis disautonómicas, dada las dificultades que existen para su diagnóstico, detección precoz y ausencia de literatura al respecto. Por tal motivo nos propusimos evaluar en forma prospectiva los pacientes con tétanos severo sometidos a monitoreo hemodinámico invasivo y de la perfusión del territorio esplácnico, particularmente durante los episodios de sobreactividad del sistema nervioso autónomo. Así, durante 20 crisis disautonómicas desarrolladas en 12 pacientes consecutivos se evidenció una profunda depresión miocárdica e hipoxia tisular, los que pueden constituir factores de riesgo clave que ayuden a explicar la elevada morbimortalidad cuando el síndrome hace su aparición en el marco del tétanos severo

Eficacia de la precuración con bromuro de pancuronio para evitar el aumento de la presión intraocular

Los relajantes musculares despolarizados como la succinilcolina, elevan la presion intraocular, este efecto puede ser prevenido mediante la administracion de un microdosis de otro tipo de relajante, el despolarizante bromuro de pancuronio, antes de la adminstración de succinilcolina. El presente es un ensayo clínico, en el cual existieron dos grupos de pacientes, en el primer grupo se administró succinilcolina sola como relajante para anestesia general, y en el segundo se realizo precurización. Se efectuó medición de la presion intraocular mediante tenometría, antes y despues de la inducción anestésica. Los resultados confirman que se puede prevenir el aumento de la presión intraocular utilizando una dosis pequeña de relajante no despolarizante, siendo esta medida de utildad aún en pacientes con trauma ocular abierto.

Pancuronium or vecuronium for treatment of shivering after cardiac surgery.

This randomized double-blind study compared the hemodynamic and metabolic effects of pancuronium and vecuronium during treatment of shivering after cardiac surgery with hypothermic cardiopulmonary bypass. Thirty sedated and pain-free patients who shivered after cardiac surgery were treated with pancuronium (n = 15) or vecuronium (n = 15) 0.08 mg/kg. Baseline values of heart rate (HR), mean arterial pressure, arterial and venous blood gases, total body oxygen consumption indexed to body surface area (VO2-I), and pressure work index (PWI, an estimate of myocardial oxygen consumption) were measured on arrival in the intensive care unit, at onset of shivering, and repeatedly for 2 h after treatment. Continuous ST segment analysis of leads II and V5 were used for detection of myocardial ischemia. Treatment of shivering with pancuronium decreased VO2-I by 32% (P = 0.0001). This was accompanied by a 14% increase in HR (P = 0.001) and a 10% increase in PWI (P = 0.03). Vecuronium decreased VO2-I by 36% (P = 0.003) with a 4% decrease in HR (P = 0.04) and a 6% decrease in PWI (P = 0.06). Myocardial ischemia (n = 3) and ventricular arrhythmias (n = 3) occurred in five patients treated with pancuronium. Only one patient treated with vecuronium had ventricular arrhythmia (P = 0.08). Seven patients treated with pancuronium and eight treated with vecuronium were taking beta-adrenergic blockers preoperatively which was associated with lower HR (96 +/- 16 vs 109 +/- 15 bpm; P = 0.025) and lower PWI (8.8 +/- 1.2 vs 10.7 +/- 1.92 mL.min-1 x 100 g-1; P = 0.003) at onset of shivering. However, beta-adrenergic blockers did not attenuate the relative HR increase induced by pancuronium. No relationship was found between hypercapnia and tachycardia or hypertension. These results suggest that, when compared to pancuronium for treatment of postoperative shivering, vecuronium may be advantageous because it does not increase myocardial work. The disproportionate relationship between VO2-I and PWI after treatment with muscle relaxants indicates that increased VO2-I does not contribute significantly to the hemodynamic disturbances associated with shivering. These disturbances are more likely the results of increased adrenergic activity related to pain and recovery from anesthesia. Shivering and its associated hemodynamic disturbances appear to be concomitant but independent signs of awakening.

[Rhabdomyolysis in severe acute asthma]. / Rhabdomyolyse au cours d'un asthme aigu grave.

A case is reported of a 74-year-old man who developed rhabdomyolysis during treatment for status asthmaticus. This patient had a history of asthma. He was admitted after a cardiac arrest during a severe asthma attack. Continuous muscle relaxation (4 mg.h-1 of pancuronium for 10 days; total dose 960 mg) was required to carry out mechanical ventilation. Bronchodilators and high doses of steroids (300 mg.day-1 of methylprednisolone for 10 days) were also given. After the administration of muscle relaxant had been discontinued, the patient displayed a severe, predominantly proximal, quadriplegia as well as a raised blood creatinine kinase concentration. The urine was brown coloured over a 24 h period. Rhabdomyolysis was confirmed by muscle biopsy. The patient recovered over a period of one month. This case is discussed in the light of some other similar reports in the literature. It seems that the combination of muscle relaxant with high doses of steroids is to be incriminated.

[Status asthmaticus. Acute myopathy induced by cortisone and neuropathy during resuscitation]. / Etat de mal asthmatique. Myopathie aiguë cortisonique et neuropathie de réanimation.

A female patient treated by mechanical ventilation with high doses of pancuronium and methylprednisolone for status asthmaticus presented with acute total areflexic and severe amyotrophic tetraplegia; she died after multiple organ failure. Muscle biopsy confirmed the clinical diagnosis of "acute corticosteroid myopathy", precipitated by a corticosteroid "disuse hypersensitivity" after pancuronium. The electromyogram showed a critical illness polyneuropathy, secondary to multiple organ failure. Nerve biopsy was normal. The respective parts played by corticosteroids, curare-like derivatives and intensive care in the genesis of unexplained difficulty in weaning from the ventilator are discussed.

Comparison of meperidine and pancuronium for the treatment of shivering after cardiac surgery.

Shivering after cardiac surgery can produce adverse haemodynamic and metabolic sequelae. In this study, the metabolic effects of shivering and the efficacy of treatment with meperidine or pancuronium were studied, using a metabolic cart, in 61 patients who had undergone cardiac surgery. The patients received premedication with morphine, perphenazine and diazepam or lorazepam, and were anaesthetised with fentanyl or sufentanil and diazepam. Muscle relaxation was achieved with pancuronium. Patients were monitored with a radial arterial line, pulmonary artery catheter and oesophageal and urinary bladder temperature probes. Rewarming to an oesophageal temperature of 38 degrees C was achieved before the termination of CPB and was maintained for a minimum of 15 min reperfusion time. Every 15 min after surgery, the patients' temperature at three sites (pulmonary artery, oesophagus, bladder) and shivering scores were monitored. Hourly measurements were made of haemodynamic variables (MAP, PAOP, CVP, SVR, PVR, CI), carbon dioxide production, oxygen consumption and respiratory quotient. If the patient shivered, the measurements were recorded prior to drug treatment and repeated 30 min later following randomization to either: meperidine 0.25 mg.kg-1 (Group 1), meperidine 0.5 mg.kg-1 (Group 2) or pancuronium 0.06 mg.kg-1 intravenously (Group 3). Thirty-two patients shivered and mean VO2 and VCO2 values were greater in the shivering group than in the nonshivering patients (VO2 334.8 +/- 17.6 vs. 240.5 +/- 8.8 ml.min-1; VCO2 238.8 +/- 17.2 vs 199.2 +/- 8.4 ml.min-1, P = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

National survey of diagnosis and management of persistent pulmonary hypertension of the newborn.

The diagnosis and management of persistent pulmonary hypertension of the newborn remains controversial. A national survey was performed to analyze recent trends in the incidence, diagnosis, management, and survival of patients with persistent pulmonary hypertension of the neonate. Sixty-six institutions from all geographical regions responded. The overall admission incidence was 3.9% +/- 2.6%. Secondary persistent pulmonary hypertension of the neonate was more common than primary. Unexplained hypoxemia, ductal level right-to-left shunting, echocardiography, and a positive response to hyperventilation were all used frequently (in at least 79% of institutions) to diagnose persistent pulmonary hypertension of the neonate. The majority of institutions considered a positive response to hyperventilation to be determined by an increase of PaO2 by 30 mm Hg with a concomitant decrease in PaCO2 to 25 mm Hg. Approximately 70% of institutions use varying ventilator techniques (ie, with or without hyperventilation), but the majority use hyperventilation predominantly. Almost all (greater than 90%) institutions used muscle paralytic agents and pulmonary vasodilators. Tolazoline was the first choice of pulmonary vasodilator therapy. The overall survival rate of persistent pulmonary hypertension of the newborn was 77.4% +/- 13.4%. Survival rate did not differ between different geographic areas of the country. There was a trend noted for improved survival with less use of muscle paralyzing agents. Yet despite varying treatment protocols, survival rates are improving.

Comparative clinical evaluation of chandonium iodide and pancuronium bromide as muscle relaxant.

Chandonium iodide, a synthetic non-depolarising neuromuscular blocking agent and pancuronium bromide were clinically compared as muscle relaxants in 62 patients undergoing elective surgery. Anaesthesia was induced by thiopentone sodium and maintained by oxygen and nitrous oxide. Assessment of efficacy of both the muscle relaxants was graded taking into consideration intubating condition and muscular relaxation during surgery. Tolerability was assessed by noting the changes in heart rate, blood pressure and biochemical estimations. Efficacy of chandonium iodide in the dose of 0.15 to 0.18 mg/kg was comparable to that of 0.08 to 0.1 mg/kg of pancuronium bromide. Both the drugs were well tolerated.