Ultrasound evaluation of diaphragm function in mechanically ventilated patients: comparison to phrenic stimulation and prognostic implications

Background: Intensive care unit (ICU)-acquired weakness and diaphragm dysfunction are frequent conditions, both associated with poor prognosis in critically ill patients. While it is well established that ICU-acquired weakness severely impairs long-term prognosis, the association of diaphragm dysfunction with this outcome has never been reported. This study investigated whether diaphragm dysfunction is associated with negative long-term outcomes and whether the coexistence of diaphragm dysfunction and ICU-acquired weakness has a particular association with 2-year survival and health-related quality of life (HRQOL). Methods:This study is an ancillary study derived from an observational cohort study. Patients under mechanical ventilation were enrolled at the time of their first spontaneous breathing trial. Diaphragm dysfunction was defined by tracheal pressure generated by phrenic nerve stimulation < 11 cmH 2 O and ICU-acquired weakness was defined by Medical Research Council (MRC) score < 48. HRQOL was evaluated with the SF-36 questionnaire.Results: Sixty-nine of the 76 patients enrolled in the original study were included in the survival analysis and 40 were interviewed. Overall 2-year survival was 67% (46/69): 64% (29/45) in patients with diaphragm dysfunction, 71% (17/24) in patients without diaphragm dysfunction, 46% (11/24) in patients with ICU-acquired weakness and 76% (34/45) in patients without ICU-acquired weakness. Patients with concomitant diaphragm dysfunction and ICU-acquired weakness had a poorer outcome with a 2-year survival rate of 36% (5/14) compared to patients without diaphragm function and ICU-acquired weakness [79% (11/14) (p < 0.01)]. Health-related quality of life was not influenced by the presence of ICU-acquired weakness, diaphragm dysfunction or their coexistence.Conclusions: ICU-acquired weakness but not diaphragm dysfunction was associated with a poor 2-year survival of critically ill patients.

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“…Informed consent was obtained from all patients or their relatives. Some data from this cohort have already been published elsewhere [13,18,19].…”

Section: Methodsmentioning

confidence: 99%

ICU-acquired weakness, diaphragm dysfunction and long-term outcomes of critically ill patients

Saccheri

Morawiec

Delemazure

et al. 2020

Ann. Intensive Care

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“…The full detailed method for diaphragm ultrasound has been reported elsewhere. 12 Phrenic Nerve Stimulation. Diaphragm pressure generating capacity was assessed in terms of changes in endotracheal tube pressure induced by bilateral phrenic nerve stimulation during airway occlusion in substudy C. Phrenic nerve stimulation was performed by bilateral anterior magnetic stimulation as reported elsewhere 4,13 (see the Supplemental Digital Content 1 that displays a detailed description of the technique,http://links.lww.com/ALN/C264).…”

Section: Measurementsmentioning

confidence: 99%

Usefulness of Parasternal Intercostal Muscle Ultrasound during Weaning from Mechanical Ventilation

et al. 2020

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Background The assessment of diaphragm function with diaphragm ultrasound seems to bring important clinical information to describe diaphragm work and weakness. When the diaphragm is weak, extradiaphragmatic muscles may play an important role, but whether ultrasound can also assess their activity and function is unknown. This study aimed to (1) evaluate the feasibility of measuring the thickening of the parasternal intercostal and investigate the responsiveness of this muscle to assisted ventilation; and (2) evaluate whether a combined evaluation of the parasternal and the diaphragm could predict failure of a spontaneous breathing trial. Methods First, an exploratory evaluation of the parasternal in 23 healthy subjects. Second, the responsiveness of parasternal to several pressure support levels were studied in 16 patients. Last, parasternal activity was compared in presence or absence of diaphragm dysfunction (assessed by magnetic stimulation of the phrenic nerves and ultrasound) and in case of success/failure of a spontaneous breathing trial in 54 patients. Results The parasternal was easily accessible in all patients. The interobserver reproducibility was good (intraclass correlation coefficient, 0.77 (95% CI, 0.53 to 0.89). There was a progressive decrease in parasternal muscle thickening fraction with increasing levels of pressure support (Spearman ρ = −0.61 [95% CI, −0.74 to −0.44]; P < 0.0001) and an inverse correlation between parasternal muscle thickening fraction and the pressure generating capacity of the diaphragm (Spearman ρ = −0.79 [95% CI, −0.87 to −0.66]; P < 0.0001). The parasternal muscle thickening fraction was higher in patients with diaphragm dysfunction: 17% (10 to 25) versus 5% (3 to 8), P < 0.0001. The pressure generating capacity of the diaphragm, the diaphragm thickening fraction and the parasternal thickening fraction similarly predicted failure or the spontaneous breathing trial. Conclusions Ultrasound assessment of the parasternal intercostal muscle is feasible in the intensive care unit and provides novel information regarding the respiratory capacity load balance. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

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“…These include patients with neuromuscular disorders [2] and, more recently, patients with heart failure [8]. In addition, diaphragm ultrasound has been applied in chronic pulmonary disease [9][10][11], and ultrasound measures of diaphragmatic dysfunction have been shown to correlate with morbidity and poor prognosis in mechanically ventilated patients and in patients with chronic obstructive pulmonary disease (COPD) [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Respiratory Muscle Strength and Diaphragm Ultrasound: Normative Values, Theoretical Considerations, and Practical Recommendations

et al. 2020

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Background: Reference values derived from existing diaphragm ultrasound protocols are inconsistent, and the association between sonographic measures of diaphragm function and volitional tests of respiratory muscle strength is still ambiguous. Objective: To propose a standardized and comprehensive protocol for diaphragm ultrasound in order to determine lower limits of normal (LLN) for both diaphragm excursion and thickness in healthy subjects and to explore the association between volitional tests of respiratory muscle strength and diaphragm ultrasound parameters. Methods: Seventy healthy adult subjects (25 men, 45 women; age 34 ± 13 years) underwent spirometric lung function testing, determination of maximal inspiratory and expiratory pressure along with ultrasound evaluation of diaphragm excursion and thickness during tidal breathing, deep breathing, and maximum voluntary sniff. Excursion data were collected for amplitude and velocity of diaphragm displacement. Diaphragm thickness was measured in the zone of apposition at total lung capacity (TLC) and functional residual capacity (FRC). All participants underwent invasive measurement of transdiaphragmatic pressure (Pdi) during different voluntary breathing maneuvers. Results: Ultrasound data were successfully obtained in all participants (procedure duration 12 ± 3 min). LLNs (defined as the 5th percentile) for diaphragm excursion were as follows: (a) during tidal breathing: 1.2 cm (males; M) and 1.2 cm (females; F) for amplitude, and 0.8 cm/s (M) and 0.8 cm/s (F) for velocity, (b) during maximum voluntary sniff: 2.0 cm (M) and 1.5 cm (F) for amplitude, and 6.7 (M) cm/s and 5.2 cm/s (F) for velocity, and (c) at TLC: 7.9 cm (M) and 6.4 cm (F) for amplitude. LLN for diaphragm thickness was 0.17 cm (M) and 0.15 cm (F) at FRC, and 0.46 Spiesshoefer et al. cm (M) and 0.35 cm (F) at TLC. Values for males were consistently higher than for females, independent of age. LLN for diaphragmatic thickening ratio was 2.2 with no difference between genders. LLN for invasively measured Pdi during different breathing maneuvers are presented. Voluntary Pdi showed only weak correlation with both diaphragm excursion velocity and amplitude during forced inspiration. Conclusions: Diaphragm ultrasound is an easy-to-perform and reproducible diagnostic tool for noninvasive assessment of diaphragm excursion and thickness. It supplements but does not replace respiratory muscle strength testing.

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Ultrasound evaluation of diaphragm function in mechanically ventilated patients: comparison to phrenic stimulation and prognostic implications

Abstract: Under ACV, diaphragm thickness, EXdi and TFdi were uncorrelated to Ptr,stim. Under PSV, TFdi was strongly correlated to diaphragm strength and both were predictors of remaining length of MV and ICU and hospital death.

Cited by 135 publications

References 39 publications

ICU-acquired weakness, diaphragm dysfunction and long-term outcomes of critically ill patients

ICU-acquired weakness, diaphragm dysfunction and long-term outcomes of critically ill patients

Usefulness of Parasternal Intercostal Muscle Ultrasound during Weaning from Mechanical Ventilation

Evaluation of Respiratory Muscle Strength and Diaphragm Ultrasound: Normative Values, Theoretical Considerations, and Practical Recommendations

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