Muscle atrophy in mechanically-ventilated critically ill children

Abstract

ImportanceICU-acquired muscle atrophy occurs commonly and worsens outcomes in adults. The incidence and severity of muscle atrophy in critically ill children are poorly characterized.ObjectiveTo determine incidence, severity and risk factors for muscle atrophy in critically ill children.Design, setting and participantsA single-center, prospective cohort study of 34 children receiving invasive mechanical ventilation for ≥48 hours. Patients 1 week– 18 years old with respiratory failure and without preexisting neuromuscular disease or skeletal trauma were recruited from a tertiary Pediatric Intensive Care Unit (PICU) between June 2015 and May 2016. We used serial bedside ultrasound to assess thickness of the diaphragm, biceps brachii/brachialis, quadriceps femoris and tibialis anterior. Serial electrical impedance myography (EIM) was assessed in children >1 year old. Medical records were abstracted from an electronic database.ExposuresRespiratory failure requiring endotracheal intubation for ≥48 hours.Main outcome and measuresThe primary outcome was percent change in muscle thickness. Secondary outcomes were changes in EIM-derived fat percentage and “quality”.ResultsOf 34 enrolled patients, 30 completed ≥2 ultrasound assessments with a median interval of 6 (IQR 6–7) days. Mean age was 5.42 years, with 12 infants <1 year (40%) and 18 children >1 year old (60%). In the entire cohort, diaphragm thickness decreased 11.1% (95%CI, -19.7% to -2.52%) between the first two assessments or 2.2%/day. Quadriceps thickness decreased 8.62% (95%CI, -15.7% to -1.54%) or 1.5%/day. Biceps (-1.71%; 95%CI, -8.15% to 4.73%) and tibialis (0.52%; 95%CI, -5.81% to 3.40%) thicknesses did not change. Among the entire cohort, 47% (14/30) experienced diaphragm atrophy (defined a priori as ≥10% decrease in thickness). Eighty three percent of patients (25/30) experienced atrophy in ≥1 muscle group, and 47% (14/30)—in ≥2 muscle groups. On multivariate linear regression, increasing age and traumatic brain injury (TBI) were associated with greater muscle loss. EIM revealed increased fat percentage and decreased muscle “quality”.Conclusions and relevanceIn children receiving invasive mechanical ventilation, diaphragm and other skeletal muscle atrophy is common and rapid. Increasing age and TBI may increase severity of limb muscle atrophy. Prospective studies are required to link muscle atrophy to functional outcomes in critically ill children.

Diaphragmatic atrophy and dysfunction in critically ill mechanically ventilated children

“…In our cohort, median diaphragmatic atrophy and atrophy rate over the first week of ventilation were 9.91% and 2.01% per day, respectively. These results are similar to studies by Glau et al 1 ( n = 51) and Johnson et al 8 ( n = 34) in children with acute respiratory failure. Though our cohort has lesser diaphragmatic atrophy rate than seen in the study by Glau et al's 1 (3.4% per day) but was similar to Johnson et al's 8 cohort (2.2% per day).…”

“…These results are similar to studies by Glau et al 1 ( n = 51) and Johnson et al 8 ( n = 34) in children with acute respiratory failure. Though our cohort has lesser diaphragmatic atrophy rate than seen in the study by Glau et al's 1 (3.4% per day) but was similar to Johnson et al's 8 cohort (2.2% per day). More than half of second DTe values in Johnson et al's 8 study were done after extubation.…”

“…Though our cohort has lesser diaphragmatic atrophy rate than seen in the study by Glau et al's 1 (3.4% per day) but was similar to Johnson et al's 8 cohort (2.2% per day). More than half of second DTe values in Johnson et al's 8 study were done after extubation. After extubation, the diaphragm moves cranially due to loss of positive end‐expiratory pressure (PEEP) which leads to lengthening and thinning of diaphragm muscle fibers, hence smaller DTe 17 .…”

“…Two pediatric studies showed significant diaphragmatic atrophy, while one showed only minor changes in DTe over the first week 1,6,8 . All of these studies represented children from developed economies 1,6,8 . Prevalent malnutrition in developing countries is associated with prolonged mechanical ventilation and hospital stay 9 .…”

A prospective observational study on critically ill children with diaphragmatic dysfunction: clinical outcomes and risk factors

“…There are several reports on the causes of DD and associated clinical outcomes in adult patients with a critical illness. However, there are not many studies on DD in pediatric patients with a critical illness, the associated risk factors, with limited information on its impact on clinical outcomes in children [12][13][14] . Therefore, there is little experience in clinical identification, proper intervention and prognostic improvement of children in such cases.…”