Short-term effects of positive expiratory airway pressure in patients being weaned from mechanical ventilation

OBJECTIVE: To investigate the feasibility and the cardiorespiratory effects of using positive expiratory airway pressure, a physiotherapeutic tool, in comparison with a T-tube, to wean patients from mechanical ventilation. METHODS/DESIGN: A prospective, randomized, cross-over study. SETTING: Two intensive care units. PATIENTS AND INTERVENTIONS: We evaluated forty patients who met weaning criteria and had been mechanically-ventilated for more than 48 hours, mean age 59 years, including 23 males. All patients were submitted to the T-tube and Expiratory Positive Airway Pressure devices, at 7 cm H2O, during a 30-minute period. Cardiorespiratory variables including work of breathing, respiratory rate (rr), peripheral oxygen saturation (SpO2), heart rate (hr), systolic, diastolic and mean arterial pressures (SAP, DAP, MAP) were measured in the first and thirtieth minutes. The condition was analyzed as an entire sample set (n=40) and was also divided into subconditions: chronic obstructive pulmonary disease (n=14) and non-chronic obstructive pulmonary disease (non- chronic obstructive pulmonary disease) (n=26) categories. Comparisons were made using a t-test and Analysis of Variance. The level of significance was p < 0.05. RESULTS: Our data showed an increase in work of breathing in the first and thirtieth minutes in the EPAP condition (0.86+ 0.43 and 1.02+1.3) as compared with the T-tube condition (0.25+0.26 and 0.26+0.35) (p<0.05), verified by the flow-sensor monitor (values in J/L). No statistical differences were observed when comparing the Expiratory Positive Airway Pressure and T-tube conditions with regard to cardiorespiratory measurements. The same result was observed for both chronic obstructive pulmonary disease and non- chronic obstructive pulmonary disease subconditions. CONCLUSIONS: Our study demonstrated that, in weaning patients from mechanical ventilation, the use of a fixed level of Expiratory Positive Airway Pressure caused ...

Desmame da ventilacão mecânica utilizando pressão de suporte ou tubo T: comparacão entre pacientes cardiopatas e não cardiopatas / Weaning from mechanical ventilation by using pressure support or T-tube ventilation: comparison between patients with and without heart disease

OBJETIVO: Analisar variáveis cardiorrespiratórias durante o desmame com as técnicas tubo T e pressão de suporte e compará-las em grupos de cardiopatas e não cardiopatas. MÉTODOS: Avaliados 20 pacientes (57n15 anos) quanto à: oxigenacão, eliminacão de CO2, freqüência respiratória e cardíaca, volume corrente e volume minuto, freqüência cardíaca, pressão arterial e alteracões eletrocardiográficas. Os dados foram registrados, em ambas as técnicas, aos zero, 15 e 30 min, com intervalo de 30 min. Os pacientes foram divididos em cardiopatas (n=11) e não cardiopatas (n=9) e comparados. RESULTADOS: Comparando-se pressão de suporte com tubo T demonstraram-se: valores de oxigenacão e eliminacão de CO2 significativamente mais elevados e freqüência respiratória reduzidos. Não houve diferenca quanto à pressão arterial e freqüência cardíaca. Comparando-se cardiopatas versus não cardiopatas, foram verificadas, respectivamente, alteracões de segmento ST em 7 (64 por cento) versus 2 (22 por cento), arritmias em 3 (27 por cento) versus 1 (11 por cento) e menor ocorrência de taquicardia. CONCLUSAO: Na comparacão de pressão de suporte com tubo T uma melhor resposta foi observada nas medidas de parâmetros respiratórios e de oxigenacão com o uso de pressão de suporte, não havendo diferencas significativas nas medidas de parâmetros cardiovasculares. Houve menor ocorrência de taquicardia, maior ocorrência de alteracões de segmento ST e tendência à maior ocorrência de arritmias nos cardiopatas, em ambos os modos de desmame.