Early mobilization during mechanical ventilation reduces risk for cognitive impairment
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Early mobilization of mechanically ventilated adults lowered the risk for cognitive impairment 1 year following hospital discharge by 19%, according to a study published in The Lancet Respiratory Medicine.
“The study finding on the impact of physical activity on cognition expands our knowledge of this important relationship,” John P. Kress, MD, director of the medical ICU at University of Chicago Medicine, told Healio.
In a single-center, parallel, randomized controlled trial, Kress and colleagues analyzed 198 functionally independent adults on mechanical ventilation in the ICU for less than 96 hours, with at least 24 more hours planned, to assess whether early mobilization could lower the incidence of cognitive impairment 1 year after hospital discharge.
Researchers randomly assigned patients 1:1 to receive either early mobilization, which included physical and occupational therapy within the first 96 hours of mechanical ventilation (n = 99; mean age, 57.9 years; 59% men), or usual care (n = 99; mean age, 54.5 years; 56% men).
At both hospital discharge and 1 year following discharge researchers evaluated neuromuscular weakness, institution-free days, functional independence, quality of life and cognitive impairment, defined as a Montreal Cognitive Assessment score of less than 26. Cognitive impairment at 1 year — for which 89% of the early mobilization group and 88% of the usual care group had data — served as the study’s primary endpoint.
Median time from intubation to the first therapy session was shorter for those receiving early mobilization (1.1 days; interquartile range [IQR], 0.8-2) than for those receiving usual care (4.7 days; IQR, 3.3-6.8; P < .0001).
At hospital discharge, cognitive impairment occurred among more patients in the usual care group than in the early mobilization group (69% vs. 54%; difference = –15.2%; 95% CI, –28.6% to –1.7%; P = .029).
Similarly, at 1 year, researchers found fewer patients with cognitive impairment in the early mobilization group than the usual care group (24% vs. 43%; absolute difference = –19.2%; 95% CI, –32.1 to –6.3%; P = .0043).
With early mobilization, researchers found a 19% (RR = 0.81; 95% CI, 0.68-0.96) reduced risk for cognitive impairment.
“Early mobilization in the ICU is extremely difficult and takes a dedicated team,” Kress told Healio. “Time is of the essence since waiting several days before starting will lead to failure, which is what happened in the usual care team study — the intervention was delayed.”
Compared with patients receiving usual care, fewer patients receiving early mobilization had ICU-acquired weaknesses at 1 year (0% vs. 14%; difference = –14.1%; 95% CI, –21 to –7.3; P = .0001).
Quality-of-life tests also demonstrated that the early mobilization group had better physical component scores compared with patients in the usual care group (median, 52.4; IQR, 45.3-56.8 vs. 41.1; IQR, 31.8-49.4; P < .0001), although researchers found no significant differences in rate of functional independence (65% vs. 62%; difference = 3%, 95% CI, –10.4 to 16.5%) and quality-of-life mental component scores (median 55.9; IQR, 50.2-58.9 vs. 55.2; IQR, 49.5-59.7).
Six patients receiving early mobilization experienced adverse events compared with no patients in the usual care group (P = .029). These included tachycardia in two patients, and hypotension, tachypnoea, oxygen desaturation, arterial catheter removal and rectal tube removal in one patient each.
“In future studies, we need to determine which patients are most likely to benefit from an intervention that comes from scarce resources (ie, we don’t have unlimited physical and occupational therapists for the ICU),” Kress told Healio.
This study by Kress and colleagues adds new evidence to the literature on the benefits of early mobilization, according to an accompanying editorial by Timothy D. Girard, MD, MSCI, assistant professor of medicine at University of Pittsburgh School of Medicine, and Pratik P. Pandharipande, MD, MSCI, professor of anesthesiology and surgery at Vanderbilt University Medical Center.
“These results add to a growing body of evidence showing that mobilization as early as possible, when coupled with light sedation, avoidance of benzodiazepines and other delirium risk factors, improves outcomes for patients treated in the ICU,” Girard and Pandharipande wrote. “Specifically, these findings are the first from a randomized controlled trial linking early mobilization to improvement in long-term cognitive and physical outcomes, which are patient-centered and which many patients prioritize over survival.”
For more information:
John P. Kress, MD, can be reached at jkress@bsd.uchicago.edu.
Reference:
Perspective
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Carol L. Hodgson, PhD, FACP, FAHMS
There is an urgent need for additional data about the long-term functional outcomes of survivors of critical illness and early interventions that may reduce long-term deficits. This study aimed to address these knowledge gaps.
Overall, the authors found that early mobilization was associated with improved cognitive function at 12 months. These findings are surprising as previous systematic reviews have been unable to demonstrate an effect of early mobilization on cognitive function due to heterogeneity of interventions and small sample sizes.
The authors acknowledge that the single-center design, with large effect sizes and small sample size, restricts the generalizability of their findings. Indeed, these findings are not consistent with previous studies or a recent international, multicenter trial that included 750 patients randomly assigned to early mobilization vs. standard care and found no difference in cognitive function at 6 months (the TEAM trial).
The difference in findings between the study by Patel and colleagues and other trials may be due to the difference in the usual care arm. This study delivered very limited mobilization to patients allocated to usual care, which is not consistent with international guidelines or current clinical practice worldwide. Only 6% of patients in the usual care arm were mobilized in the ICU, whereas in the TEAM trial, 77% of patients in the usual care arm stood and 41% of patients walked. The differences in usual care may be because the study by Patel and colleagues took 8 years to complete; therefore, it began over a decade ago and before most of the current guidelines were developed.
Another important limitation of the study includes that there was only a fraction of the cohort available for evaluation of cognition function at 12 months (n = 127 of 198; 64%), which may have resulted in responder bias.
This interesting study provided much needed long-term follow-up data for cognitive function after early mobilization in the ICU. Although the results are promising, the lack of early mobilization in the usual care arm and the small sample size with a large amount of missing data for the primary outcome mean that the results need to be replicated in a larger study prior to implementation.
Reference:
Hodgson CL, et al. N Engl J Med. 2022;doi:10.1056/NEJMoa2209083.
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