Pendelluft diagnosed from ventilator weaning indexes obtained through bioelectrical impedance tomography: a case report

Abstract

CONTEXT: Today, through major technological advances in diagnostic resources within medicine, evaluation and monitoring of clinical parameters at the patient's bedside in intensive care units (ICUs) has become possible. CASE REPORT: This case report presents results and interpretations from predictive mechanical ventilation weaning indexes obtained through monitoring using chest electrical bioimpedance tomography. These indexes included maximum inspiratory pressure, maximum expiratory pressure, shallow breathing index and spontaneous breathing test. These were correlated with variations in tidal volume variables, respiratory rate, mean arterial pressure and peripheral oxygen saturation. Regarding the air distribution behavior in the pulmonary parenchyma, the patient showed the pendelluft phenomenon. Pendelluft occurs due to the time constant (product of the airways resistance and compliance) asymmetry between adjacent lung. CONCLUSION: Bioelectrical impedance tomography can help in weaning from mechanical ventilation, as in the case presented here. Pendelluft was defined as a limitation during the weaning tests. RESUMO CONTEXTO:Atualmente, com o grande avanço tecnológico em recursos para diagnósticos em medicina, a avaliação e a monitorização de parâmetros clínicos à beira leito de paciente em unidade de terapia intensiva (UTI) se tornou possível. RELATO DE CASO: Neste relato de caso, apresentam-se os resultados e a interpretação de índices preditivos de desmame da ventilação mecânica obtidos pela tomografia de bioimpedância elétrica torácica. Esses índices incluíram a pressão inspiratória máxima, pressão expiratória máxima, índice de respiração superficial e teste de respiração espontânea. Estes estavam correlacionados com as variações de volume corrente, frequência respiratória, pressão arterial média e saturação periférica de oxigênio. Quanto ao comportamento da distribuição de ar no parênquima pulmonar, o paciente apresentou o fenômeno pendelluft. O pendelluft ocorre dado pela constante de tempo (produto da resistência e complacência das vias aéreas) de forma assimétrica entre as unidades pulmonares adjacentes. CONCLUSÃO: A tomografia de bioimpedância pode auxiliar no desmame da ventilação mecânica, como no caso apresentado. Pendelluft foi definido como limitação durante a execução dos testes para desmame.

Prevalence and prognosis of respiratory pendelluft phenomenon in mechanically ventilated ICU patients with acute respiratory failure: a retrospective cohort study

“…Since the first report of “occult pendelluft” phenomenon in anesthetized pigs with acute lung injury and a patient with acute respiratory distress syndrome (ARDS) in 2013 [ 3 ], EIT has been increasingly used to detect the pendelluft in critically ill patients [ 14 – 17 ]. At least two studies tried to quantitatively assess the gas volume subjected to pendelluft and moving within the lungs through EIT-based algorithms.…”

“…Since the first report of "occult pendelluft" phenomenon in anesthetized pigs with acute lung injury and a patient with acute respiratory distress syndrome (ARDS) in 2013 [3], EIT has been increasingly used to detect the pendelluft in critically ill patients [14][15][16][17]. At least two studies tried to quantitatively assess the gas volume subjected to pendelluft and moving within the lungs through [9] introduced a method to detect the amplitude of pendelluft by comparing the sum of all pixel TIV with the global TIV, and expressed it as percent, where 1% of pendelluft amplitude was equal to 1 mL pendelluft volume per 100 mL tidal volume.…”