Structural differences in the diaphragm of patients following controlled vs. assisted and spontaneous Mechanical Ventilation
Mechanical Ventilation (MV) is associated with adverse effects on respiratory muscle, including atrophy. Ventilatory Induced Diaphragm Dysfunction (VIDD), due to continuous MV, is one of the causes of difficult ventilatory weaning.
The authors conducted a prospective study on 35 patients, using immune-histochemical analysis on quadriceps and diaphragm samples from Maastricht III patients (MSIII, 16 cases) and Brain Dead patients (BD, 14 cases). 5 Controls (CTL) undergoing thoracic surgery were also included.
The author tested whether MSIII donors, who are able to stimulate their diaphragm, may present less VIDD than BD donors. Data on patient characteristics, comorbidities and Mechanical Ventilation was collected with biopsies from the anterior costal diaphragm and from the vastus medialis.
The size of type I and type II fibres was significantly reduced in the diaphragm and quadriceps of both MSIII and BD patients compared to CTL.
Myosin chains were similar in diaphragm between BD and MSIII, while they were reduced in quadriceps of MSIII compared to BD.
Cross-sectional area of diaphragmatic fibres was reduced in both MSIII and BD patients compared to CTL, and it was lower in quadriceps fibres of MSIII compared to BD.
MSIII patients who stimulate the diaphragm for longer time have a larger cross-sectional area and a lower proportion of lipofuscin in diaphragm fibres than BD patients.
The authors conclude that this study provides the first evidence that preserving diaphragm stimulation reduces VIDD.
STUDY STRENGTHS & LIMITATIONS
- This is the first study to analyse the histological characteristics of diaphragm and peripheral muscle in human samples
- A study limitation is the comparison of different types of patients, undergoing non-homogeneous modes of ventilation. However, the new model based on the MSIII population is also one of the strengths of the study.
TAKE HOME MESSAGE
- Patients able to stimulate the diaphragm have less Ventilator Induced Diaphragm Dysfunction than brain death patients
- This is demonstrated by the accumulation of more lipofuscin deposit – a proxy for oxidative stress and cell protein degradation – in BD patients compared to MSIII patients, and by lower cross-section area in fibres of unstimulated patients.
- The results suggest that deleterious effect of MV may be attenuated by maintaining a certain level of respiratory muscle stimulation
This article review was prepared and submitted by Massimiliano Greco on behalf of the NEXT Committee and ESICM Journal Review Club.
1) Marin-Corral J, Dot I, Boguña M, Cecchini L, Zapatero A, Gracia MP, Pascual-Guardia S, Vilà C, Castellví A, Pérez-Terán P, Gea J, Masclans JR. Structural differences in the diaphragm of patients following controlled vs assisted and spontaneous mechanical ventilation. Intensive Care Med. 2019 Apr;45(4)