Gastric intramucosal pH and intraluminal PCO2 during weaning from mechanical ventilation.

OBJECTIVE: To study the value of gastric intramucosal pH and gastric intraluminal PCO2 measurements to predict weaning outcome from mechanical ventilation. DESIGN: Prospective clinical study. SETTING: Intensive care medicine department of a university hospital. PATIENTS: Nineteen adult critically ill patients who were mechanically ventilated because of acute respiratory failure and were considered ready to be weaned. INTERVENTIONS: The patients were weaned with: synchronized intermittent mandatory ventilation plus positive end-expiratory pressure (SIMV+PEEP) or continuous positive airway pressure with pressure support ventilation (CPAP+PSV). A gastric tonometer was placed in all the patients. Tonometric, respiratory, and hemodynamic variables were measured during the weaning process. MEASUREMENTS: Hemodynamic variables, respiratory mechanics, pulmonary gas exchange, respiratory muscle force, spontaneous pattern of breathing, and the central control of breathing were recorded. Simultaneously, the intramucosal pH and gastric intraluminal PCO2 were measured. MAIN RESULTS: Eleven patients were successfully extubated and eight failed. The patients who failed showed higher values of mouth occlusion pressure, respiratory rate, and effective inspiratory impedance (mouth occlusion pressure/mean inspiratory flow). The intramucosal pH was initially 7.19 +/- 0.22 and decreased to 7.10 +/- 0.16 during the weaning process in patients who failed (p < .05). At the same time, the intramucosal pH showed a nonsignificant change from 7.36 +/- 0.07 to 7.32 +/- 0.07 in the patients who were successfully extubated. The intramucosal pH was statistically different when both groups were compared during the initial and the final evaluations (p < .05). For the initial evaluation, the sensitivity and specificity to predict weaning failure when the intramucosal pH was < or =7.30 were 0.88 (95% confidence interval [CI], 0.66-1) and 0.82 (95% CI, 0.59-1), respectively. The gastric intraluminal PCO2 was higher in patients who failed (p < .05). When gastric intraluminal PCO2 was . or =40 torr during the initial evaluation, weaning failure occurred with a sensitivity of 1 (95% CI, 0.31-1) and a specificity of 0.55 (95% CI, 0.26-0.84). CONCLUSIONS: Weaning failure was associated with gastric intramucosal acidosis. The intramucosal pH and gastric intraluminal PCO2 may be helpful to predict weaning outcome. Further controlled clinical trials in a larger group of patients are needed.

Ecocardiografía de estrés con dobutamina para la detección de isquemia y viabilidad miocardica / Echocardiography of stree with dobutamina for the ischemia detection and viability myocardic

El presente trabajo describe nuestra experiencia en el uso de la ecocardiografía de estrés con dobutamina para la detección de isquemia y viabilidad miocárdica. Entre enero de 1995 y abril de 1999 se realizaron 78 ecocardiogramas de estrés con dobutamina en el Servicio de Cardiología del HNERM. Los resultados de la movilidad parietal del ventrículo izquierdo fueron reportados según una escala arbitraria y dividiendo al ventrículo izquierdo en 16 segmentos según las recomendaciones de la Sociedad Americana de Ecocardiografia. Se encontró viabilidad miocárdica en 36 pacientes de los cuales 13 fueron revascularizados, encontrándose mejoría post-operatoria en 9 casos (valor predictivo positivo: 69,2 por ciento), en 13 pacientes no se encontró viabilidad miocárdica, dos de ellos fueron revascularizados, no evidenciándose mejoría en ninguno (valor predictivo negativo: 100 por ciento). Se encontró respuesta isquémica en 13 casos, de los cuales 9 fueron sometidos a coronariografía, encontrándose enfermedad multivaso en 8 pacientes (sensibilidad: 100 por ciento) y no encontrándose lesiones significativas en un caso (especificidad: 88 por ciento). No se presentó ningún caso de muerte, síndrome coronario agudo o arritmia maligna. Nuestros resultados son similares a los descritos en la literatura para la detección de isquemia y viabilidad miocárdica y confirman el bajo nivel de complicaciones del examen. Debido a su bajo costo y a la información que provee condiseramos que su uso para el manejo de los pacientes con enfermedad coronaria debería ser extensivamente difundido.