Weaning from mechanical ventilation: a cross-sectional study of reference values and the discriminative validity of aging.

[Purpose] To evaluate pre-extubation variables and check the discriminative validity of age as well as its correlation with weaning failure in elderly patients. [Subjects and Methods] Two hundred thirty-nine consecutive patients (48% female) who were on mechanical ventilation and had undergone orotracheal intubation were divided into four subgroups according to their age: <59 years, 60-69 years, 70-79 years, and >80 years old. The expiratory volume (VE), respiratory frequency (f), tidal volume (VT), and respiratory frequency/tidal volume ratio (f/VT) were used to examine differences in weaning parameters between the four subgroups, and age was correlated with weaning failure. [Results] The rate of weaning failure was 27.8% in patients aged >80 years and 22.1% in patients aged <60 years old. Elderly patients presented higher f/VT and f values and lower VT values. The areas under the receiver operating characteristic curves for f/VT ratio were smaller than those published previously. [Conclusion] Our results indicate that aging influences weaning criteria without causing an increase in weaning failure.

Weaning predictors do not predict extubation failure in simple-to-wean patients.

BACKGROUND: Predictor indexes are often included in weaning protocols and may help the intensive care unit (ICU) staff to reach expected weaning outcome in patients on mechanical ventilation. OBJECTIVE: The objective of this study is to evaluate the potential of weaning predictors during extubation. DESIGN: This is a prospective clinical study. SETTINGS: The study was conducted in 3 medical-surgical ICUs. PATIENTS: Five hundred consecutive unselected patients ventilated for more than 48 hours were included. METHODS AND MEASUREMENTS: All patients were extubated after 30 minutes of successful spontaneous breathing trial and followed up for 48 hours. The protocol evaluated hemodynamics, ventilation parameters, arterial blood gases, and the weaning indexes frequency to tidal volume ratio; compliance, respiratory rate, oxygenation, and pressure; maximal inspiratory pressure; maximal expiratory pressure; Pao(2)/fraction of inspired oxygen; respiratory frequency; and tidal volume during mechanical ventilation and in the 1st and 30th minute of spontaneous breathing trial. RESULTS: Reintubation rate was 22.8%, and intensive care mortality was higher in the reintubation group (10% vs 31%; P < .0001). The areas under the receiver operating characteristic curve showed that tests did not discriminate which patients could tolerate extubation. CONCLUSION: Usual weaning indexes are poor predictors for extubation outcome in the overall ICU population.

Noninvasive mechanical ventilation may be useful in treating patients who fail weaning from invasive mechanical ventilation: a randomized clinical trial.

INTRODUCTION: The use of noninvasive positive-pressure mechanical ventilation (NPPV) has been investigated in several acute respiratory failure situations. Questions remain about its benefits when used in weaning patients from invasive mechanical ventilation (IMV). The objective of this study was to evaluate the use of bi-level NPPV for patients who fail weaning from IMV. METHODS: This experimental randomized clinical trial followed up patients undergoing IMV weaning, under ventilation for more than 48 hours, and who failed a spontaneous breathing T-piece trial. Patients with contraindications to NPPV were excluded. Before T-piece placement, arterial gases, maximal inspiratory pressure, and other parameters of IMV support were measured. During the trial, respiratory rate, tidal volume, minute volume, rapid shallow breathing index, heart rate, arterial blood pressure, and peripheral oxygen saturation were measured at 1 and 30 minutes. After failing a T-piece trial, patients were randomly divided in two groups: (a) those who were extubated and placed on NPPV and (b) those who were returned to IMV. Group results were compared using the Student t test and the chi-square test. RESULTS: Of 65 patients who failed T-piece trials, 28 were placed on NPPV and 37 were placed on IMV. The ages of patients in the NPPV and IMV groups were 67.6 +/- 15.5 and 59.7 +/- 17.6 years, respectively. Heart disease, post-surgery respiratory failure, and chronic pulmonary disease aggravation were the most frequent causes of IMV use. In both groups, ventilation time before T-piece trial was 7.3 +/- 4.1 days. Heart and respiratory parameters were similar for the two groups at 1 and 30 minutes of T-piece trial. The percentage of complications in the NPPV group was lower (28.6% versus 75.7%), with lower incidences of pneumonia and tracheotomy. Length of stay in the intensive care unit and mortality were not statistically different when comparing the groups. CONCLUSION: The results suggest that NPPV is a good alternative for ventilation of patients who fail initial weaning attempts. NPPV reduces the incidence of pneumonia associated with mechanical ventilation and the need for tracheotomy. TRIAL REGISTRATION: CEP HCPA (02-114).

Variáveis de risco pré-operatório e a evolução de complicações pulmonares no pós-operatório de cirurgia torácica / Risks preoperative variables and the posoperative pulmonary complication development in thoraci surgery

O presente estudo teve como objetivo identificar variáveis no pré operatório de pacientes submetidos a cirurgias torácicas que favorecem o apareciemtno de complicações pulmonares no pós-operatório. Foram estudados 29 pacientes, no Pavilhão Pereira Filho da Santa Casa de Misericórdia/POA, no período de agosto a outubro de 2002, avaliados e estratificados em baixo, moderado e alto risco para desenvolvimento de complicações pulmonares pós-operatórias(CPP), através da Escala de PORT. Todos os pacientes foram acompanhados nas 24/48h no pós-operatório imediato a fim de dectar o desenvolvimento de CPP. A incidência de CPP foi 37,9%, considerando as variáveis como independentes; não houve associação entre a ocorrência de CPP e as variáveis: idade, tempo de tabagismo, diagnóstico, diagnóstico médico, tipo de cirurgia, presença de outras doenças respiratórias associadas, dispnéia, tosse expectoração, tiragem, alteração espirométrica, IMC, tratamento fisioterapêutico pós-operatório e a escala de PORT. Em relação às independentes "Escala de PORT" não houve associação entre os graus(notas) obtidos no pré-operatório com o estado pós-operatório(presença ou não de compilações). A variável dor torácica foi a que apresentou diferença significativa, demonstrando que pacientes com dor torácica tendem a compilar mais no pós-operatório. Concluiu-se que, embra nesse estudo os resultados não tenha sido significativos estatisticamente, imprescindível que fatores de risco sejam detectados precocemente, a fim de previnir complicações pós-cirúrgicas. A fisioterapia não teve relação significativacom os pacientes que compilaram ou não; no entanto, novas pesquisas devem buscar comprovação da eficácia da abordagem fisioterapêutica em situação cirurgica.