Observational study on passive leg raising and the autonomic nervous system
Abstract In the intensive care and perioperative setting, circulation is often supported by intravenous fluid preceded by prediction of fluid responsiveness during a passive leg raising (PLR) maneuver. An increase in stroke volume (SV) or cardiac output (CO) of 10%–15% indicates that the subject may...
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| Format: | Article |
| Language: | English |
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Wiley
2022-12-01
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| Series: | Physiological Reports |
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| Online Access: | https://doi.org/10.14814/phy2.15537 |
| _version_ | 1797397051210727424 |
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| author | Søren Søndergaard |
| author_facet | Søren Søndergaard |
| author_sort | Søren Søndergaard |
| collection | DOAJ |
| description | Abstract In the intensive care and perioperative setting, circulation is often supported by intravenous fluid preceded by prediction of fluid responsiveness during a passive leg raising (PLR) maneuver. An increase in stroke volume (SV) or cardiac output (CO) of 10%–15% indicates that the subject may increase the flow upon volume expansion. However, the semi‐recumbent position as an initial position in PLR likely reduces SV by gravitational displacement of central blood volume (CBV) to lower extremities, thereby accentuating volume responsiveness during leg raising in healthy people. Coincident with gravitational perturbations in hemodynamics, remedial changes occur in the autonomic nervous system (ANS), as expressed in spectral power in heart rate variability (HRV). This study aims to clarify these concomitant changes during PLR. A convenience number of healthy volunteers (N = 11) were recruited by advertisement in university departments. The subjects were exposed to the established PLR sequence and the heart rate (HR), mean arterial pressure (MAP), SV, and CO were sampled at 1 Hz, while electrocardiogram was recorded at 1000 Hz. Relative powers reflecting autonomic nervous system activity were assessed from spectral analysis of HRV. In response to PLR, SV increased (12.4% ± 8.7%, p < 0.0026), while HR (−7.6% ± 4.7%, p < 0.0009) and MAP (−7.6% ± 6.9%, p < 0.01) decreased, with no change in CO (4.1% ± 12.8%, ns). The HRV low‐frequency component was reduced (−34%; p < 0.0095), while the high‐frequency activity increased (78.5%; p < 0.0013), with a 63% decrease in the low/high frequency ratio (p < 0.0078). Thus, HRV indicated a reduced sympathetic index (semi‐recumbent 0.808 vs. PLR −0.177 a.u., p < 0.001) and an increased parasympathetic index (−0.141 to 0.996 a.u., p < 0.0001). Gravitational depletion and expansion of CBV during PLR were associated with a counterregulatory autonomic response. Healthy volunteers appeared volume responsive in terms of SV, but not CO. Responses to PLR are influenced by the ANS, and HRV analysis should be included in the assessment of the PLR test. |
| first_indexed | 2024-03-09T01:04:23Z |
| format | Article |
| id | doaj.art-1a78bc15bfc34bb191ff2294bd173f09 |
| institution | Directory Open Access Journal |
| issn | 2051-817X |
| language | English |
| last_indexed | 2024-03-09T01:04:23Z |
| publishDate | 2022-12-01 |
| publisher | Wiley |
| record_format | Article |
| series | Physiological Reports |
| spelling | doaj.art-1a78bc15bfc34bb191ff2294bd173f092023-12-11T10:30:37ZengWileyPhysiological Reports2051-817X2022-12-011024n/an/a10.14814/phy2.15537Observational study on passive leg raising and the autonomic nervous systemSøren Søndergaard0Department of Intensive Care and Neurointensive Stepdown Unit, Elective Surgery Centre Silkeborg Regional Hospital Silkeborg DenmarkAbstract In the intensive care and perioperative setting, circulation is often supported by intravenous fluid preceded by prediction of fluid responsiveness during a passive leg raising (PLR) maneuver. An increase in stroke volume (SV) or cardiac output (CO) of 10%–15% indicates that the subject may increase the flow upon volume expansion. However, the semi‐recumbent position as an initial position in PLR likely reduces SV by gravitational displacement of central blood volume (CBV) to lower extremities, thereby accentuating volume responsiveness during leg raising in healthy people. Coincident with gravitational perturbations in hemodynamics, remedial changes occur in the autonomic nervous system (ANS), as expressed in spectral power in heart rate variability (HRV). This study aims to clarify these concomitant changes during PLR. A convenience number of healthy volunteers (N = 11) were recruited by advertisement in university departments. The subjects were exposed to the established PLR sequence and the heart rate (HR), mean arterial pressure (MAP), SV, and CO were sampled at 1 Hz, while electrocardiogram was recorded at 1000 Hz. Relative powers reflecting autonomic nervous system activity were assessed from spectral analysis of HRV. In response to PLR, SV increased (12.4% ± 8.7%, p < 0.0026), while HR (−7.6% ± 4.7%, p < 0.0009) and MAP (−7.6% ± 6.9%, p < 0.01) decreased, with no change in CO (4.1% ± 12.8%, ns). The HRV low‐frequency component was reduced (−34%; p < 0.0095), while the high‐frequency activity increased (78.5%; p < 0.0013), with a 63% decrease in the low/high frequency ratio (p < 0.0078). Thus, HRV indicated a reduced sympathetic index (semi‐recumbent 0.808 vs. PLR −0.177 a.u., p < 0.001) and an increased parasympathetic index (−0.141 to 0.996 a.u., p < 0.0001). Gravitational depletion and expansion of CBV during PLR were associated with a counterregulatory autonomic response. Healthy volunteers appeared volume responsive in terms of SV, but not CO. Responses to PLR are influenced by the ANS, and HRV analysis should be included in the assessment of the PLR test.https://doi.org/10.14814/phy2.15537autonomic nervous systemcardiac outputheart rate variabilitypassive leg raisingpreload responsivenessstroke volume |
| spellingShingle | Søren Søndergaard Observational study on passive leg raising and the autonomic nervous system Physiological Reports autonomic nervous system cardiac output heart rate variability passive leg raising preload responsiveness stroke volume |
| title | Observational study on passive leg raising and the autonomic nervous system |
| title_full | Observational study on passive leg raising and the autonomic nervous system |
| title_fullStr | Observational study on passive leg raising and the autonomic nervous system |
| title_full_unstemmed | Observational study on passive leg raising and the autonomic nervous system |
| title_short | Observational study on passive leg raising and the autonomic nervous system |
| title_sort | observational study on passive leg raising and the autonomic nervous system |
| topic | autonomic nervous system cardiac output heart rate variability passive leg raising preload responsiveness stroke volume |
| url | https://doi.org/10.14814/phy2.15537 |
| work_keys_str_mv | AT sørensøndergaard observationalstudyonpassivelegraisingandtheautonomicnervoussystem |