Physiologic responses to exercise in survivors of critical illness: an exploratory pilot study
Abstract Background ICU survivors suffer from impaired physical function and reduced exercise capacity, yet the underlying mechanisms are poorly understood. The goal of this exploratory pilot study was to investigate potential mechanisms of exercise limitation using cardiopulmonary exercise testing...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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SpringerOpen
2022-08-01
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| Series: | Intensive Care Medicine Experimental |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s40635-022-00461-8 |
| _version_ | 1811281841788813312 |
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| author | Matthew F. Mart E. Wesley Ely James J. Tolle Mayur B. Patel Nathan E. Brummel |
| author_facet | Matthew F. Mart E. Wesley Ely James J. Tolle Mayur B. Patel Nathan E. Brummel |
| author_sort | Matthew F. Mart |
| collection | DOAJ |
| description | Abstract Background ICU survivors suffer from impaired physical function and reduced exercise capacity, yet the underlying mechanisms are poorly understood. The goal of this exploratory pilot study was to investigate potential mechanisms of exercise limitation using cardiopulmonary exercise testing (CPET) and 6-min walk testing (6MWT). Methods We enrolled adults aged 18 years or older who were treated for respiratory failure or shock in medical, surgical, or trauma ICUs at Vanderbilt University Medical Center (Nashville, TN, United States). We excluded patients with pre-existing cardiac dysfunction, a contraindication to CPET, or the need for supplemental oxygen at rest. We performed CPET and 6MWT 6 months after ICU discharge. We measured standard CPET parameters in addition to two measures of oxygen utilization during exercise (VO2-work rate slope and VO2 recovery half-time). Results We recruited 14 participants. Low exercise capacity (i.e., VO2Peak < 80% predicted) was present in 11 out of 14 (79%) with a median VO2Peak of 12.6 ml/kg/min [9.6–15.1] and 6MWT distance of 294 m [240–433]. In addition to low VO2Peak, CPET findings in survivors included low oxygen uptake efficiency slope, low oxygen pulse, elevated chronotropic index, low VO2-work rate slope, and prolonged VO2 recovery half-time, indicating impaired oxygen utilization with a hyperdynamic heart rate and ventilatory response, a pattern seen in non-critically ill patients with mitochondrial myopathies. Worse VO2-work rate slope and VO2 recovery half-time were strongly correlated with worse VO2Peak and 6MWT distance, suggesting that exercise capacity was potentially limited by impaired muscle oxygen utilization. Conclusions These exploratory data suggest ICU survivors may suffer from impaired muscular oxygen metabolism due to mitochondrial dysfunction that impairs exercise capacity long-term. These findings should be further characterized in future studies that include direct assessments of muscle mitochondrial function in ICU survivors. |
| first_indexed | 2024-04-13T01:40:47Z |
| format | Article |
| id | doaj.art-70e12b6c695f40edbf57691953913bd9 |
| institution | Directory Open Access Journal |
| issn | 2197-425X |
| language | English |
| last_indexed | 2024-04-13T01:40:47Z |
| publishDate | 2022-08-01 |
| publisher | SpringerOpen |
| record_format | Article |
| series | Intensive Care Medicine Experimental |
| spelling | doaj.art-70e12b6c695f40edbf57691953913bd92022-12-22T03:08:10ZengSpringerOpenIntensive Care Medicine Experimental2197-425X2022-08-0110111010.1186/s40635-022-00461-8Physiologic responses to exercise in survivors of critical illness: an exploratory pilot studyMatthew F. Mart0E. Wesley Ely1James J. Tolle2Mayur B. Patel3Nathan E. Brummel4Division of Allergy, Pulmonary, and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical CenterDivision of Allergy, Pulmonary, and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical CenterDivision of Allergy, Pulmonary, and Critical Care Medicine, Department of Medicine, Vanderbilt University Medical CenterCritical Illness, Brain Dysfunction, and Survivorship (CIBS) Center, Vanderbilt University Medical CenterCritical Illness, Brain Dysfunction, and Survivorship (CIBS) Center, Vanderbilt University Medical CenterAbstract Background ICU survivors suffer from impaired physical function and reduced exercise capacity, yet the underlying mechanisms are poorly understood. The goal of this exploratory pilot study was to investigate potential mechanisms of exercise limitation using cardiopulmonary exercise testing (CPET) and 6-min walk testing (6MWT). Methods We enrolled adults aged 18 years or older who were treated for respiratory failure or shock in medical, surgical, or trauma ICUs at Vanderbilt University Medical Center (Nashville, TN, United States). We excluded patients with pre-existing cardiac dysfunction, a contraindication to CPET, or the need for supplemental oxygen at rest. We performed CPET and 6MWT 6 months after ICU discharge. We measured standard CPET parameters in addition to two measures of oxygen utilization during exercise (VO2-work rate slope and VO2 recovery half-time). Results We recruited 14 participants. Low exercise capacity (i.e., VO2Peak < 80% predicted) was present in 11 out of 14 (79%) with a median VO2Peak of 12.6 ml/kg/min [9.6–15.1] and 6MWT distance of 294 m [240–433]. In addition to low VO2Peak, CPET findings in survivors included low oxygen uptake efficiency slope, low oxygen pulse, elevated chronotropic index, low VO2-work rate slope, and prolonged VO2 recovery half-time, indicating impaired oxygen utilization with a hyperdynamic heart rate and ventilatory response, a pattern seen in non-critically ill patients with mitochondrial myopathies. Worse VO2-work rate slope and VO2 recovery half-time were strongly correlated with worse VO2Peak and 6MWT distance, suggesting that exercise capacity was potentially limited by impaired muscle oxygen utilization. Conclusions These exploratory data suggest ICU survivors may suffer from impaired muscular oxygen metabolism due to mitochondrial dysfunction that impairs exercise capacity long-term. These findings should be further characterized in future studies that include direct assessments of muscle mitochondrial function in ICU survivors.https://doi.org/10.1186/s40635-022-00461-8Critical illnessCardiopulmonary exercise testPost intensive care syndrome |
| spellingShingle | Matthew F. Mart E. Wesley Ely James J. Tolle Mayur B. Patel Nathan E. Brummel Physiologic responses to exercise in survivors of critical illness: an exploratory pilot study Intensive Care Medicine Experimental Critical illness Cardiopulmonary exercise test Post intensive care syndrome |
| title | Physiologic responses to exercise in survivors of critical illness: an exploratory pilot study |
| title_full | Physiologic responses to exercise in survivors of critical illness: an exploratory pilot study |
| title_fullStr | Physiologic responses to exercise in survivors of critical illness: an exploratory pilot study |
| title_full_unstemmed | Physiologic responses to exercise in survivors of critical illness: an exploratory pilot study |
| title_short | Physiologic responses to exercise in survivors of critical illness: an exploratory pilot study |
| title_sort | physiologic responses to exercise in survivors of critical illness an exploratory pilot study |
| topic | Critical illness Cardiopulmonary exercise test Post intensive care syndrome |
| url | https://doi.org/10.1186/s40635-022-00461-8 |
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