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Effects of assisted and variable mechanical ventilation on cardiorespiratory interactions in anesthetized pigs

Effects of assisted and variable mechanical ventilation on cardiorespiratory interactions in anesthetized pigs
Effects of assisted and variable mechanical ventilation on cardiorespiratory interactions in anesthetized pigs
The physiological importance of respiratory sinus arrhythmia (RSA) and cardioventilatory coupling (CVC) has not yet been fully elucidated, but these phenomena might contribute to improve ventilation/perfusion matching, with beneficial effects on gas exchange. Furthermore, decreased RSA amplitude has been suggested as an indicator of impaired autonomic control and poor clinical outcome, also during positive-pressure mechanical ventilation (MV). However, it is currently unknown how different modes of MV, including variable tidal volumes (VT), affect RSA and CVC during anesthesia. We compared the effects of pressure controlled (PCV) versus pressure assisted (PSV) ventilation, and of random variable versus constant VT, on RSA and CVC in eight anesthetized pigs. At comparable depth of anesthesia, global hemodynamics, and ventilation, RSA amplitude increased from 20 ms in PCV to 50 ms in PSV (p < 0.05). CVC was detected (using proportional Shannon entropy of the interval between each inspiration onset and the previous R-peak in ECG) in two animals in PCV and seven animals in PSV. Variable VT did not significantly influence these phenomena. Furthermore, heart period and systolic arterial pressure oscillations were in phase during PCV but in counter-phase during PSV. At the same depth of anesthesia in pigs, PSV increases RSA amplitude and CVC compared to PCV. Our data suggest that the central respiratory drive, but not the baroreflex or the mechano-electric feedback in the heart, is the main mechanism behind the RSA increase. Hence, differences in RSA and CVC between mechanically ventilated patients might reflect the difference in ventilation mode rather than autonomic impairment. Also, since gas exchange did not increase from PCV to PSV, it is questionable whether RSA has any significance in improving ventilation/perfusion matching during MV
medical physics, biological physics
0967-3334
503-519
Beda, Alessandro
de2e8a78-d293-4c1a-bf9f-fcd384693690
Güldner, Andreas
ca8a8636-26d1-4562-a2c1-029098b40bd0
Simpson, David M.
53674880-f381-4cc9-8505-6a97eeac3c2a
Carvalho, Nadja C
a038373d-193d-4dca-b6ed-e6f6c97b9d34
Franke, Susanne
ce092d1b-681e-4689-9df2-0f3cc04955df
Uhlig, Christopher
ed29e0cf-dd4b-42e8-bfed-07ca37ee6f71
Koch, Thea
f246857d-0b5f-4453-a1f6-642c911a7c16
Pelosi, Paolo
cc5b6583-8e4d-402c-93c6-e565ba85653c
de Abreu, Marcelo Gama
6b4f5a0b-2d7b-45e0-ac68-56caca264892
Beda, Alessandro
de2e8a78-d293-4c1a-bf9f-fcd384693690
Güldner, Andreas
ca8a8636-26d1-4562-a2c1-029098b40bd0
Simpson, David M.
53674880-f381-4cc9-8505-6a97eeac3c2a
Carvalho, Nadja C
a038373d-193d-4dca-b6ed-e6f6c97b9d34
Franke, Susanne
ce092d1b-681e-4689-9df2-0f3cc04955df
Uhlig, Christopher
ed29e0cf-dd4b-42e8-bfed-07ca37ee6f71
Koch, Thea
f246857d-0b5f-4453-a1f6-642c911a7c16
Pelosi, Paolo
cc5b6583-8e4d-402c-93c6-e565ba85653c
de Abreu, Marcelo Gama
6b4f5a0b-2d7b-45e0-ac68-56caca264892

Beda, Alessandro, Güldner, Andreas, Simpson, David M., Carvalho, Nadja C, Franke, Susanne, Uhlig, Christopher, Koch, Thea, Pelosi, Paolo and de Abreu, Marcelo Gama (2012) Effects of assisted and variable mechanical ventilation on cardiorespiratory interactions in anesthetized pigs. Physiological Measurement, 33 (3), 503-519. (doi:10.1088/0967-3334/33/3/503).

Record type: Article

Abstract

The physiological importance of respiratory sinus arrhythmia (RSA) and cardioventilatory coupling (CVC) has not yet been fully elucidated, but these phenomena might contribute to improve ventilation/perfusion matching, with beneficial effects on gas exchange. Furthermore, decreased RSA amplitude has been suggested as an indicator of impaired autonomic control and poor clinical outcome, also during positive-pressure mechanical ventilation (MV). However, it is currently unknown how different modes of MV, including variable tidal volumes (VT), affect RSA and CVC during anesthesia. We compared the effects of pressure controlled (PCV) versus pressure assisted (PSV) ventilation, and of random variable versus constant VT, on RSA and CVC in eight anesthetized pigs. At comparable depth of anesthesia, global hemodynamics, and ventilation, RSA amplitude increased from 20 ms in PCV to 50 ms in PSV (p < 0.05). CVC was detected (using proportional Shannon entropy of the interval between each inspiration onset and the previous R-peak in ECG) in two animals in PCV and seven animals in PSV. Variable VT did not significantly influence these phenomena. Furthermore, heart period and systolic arterial pressure oscillations were in phase during PCV but in counter-phase during PSV. At the same depth of anesthesia in pigs, PSV increases RSA amplitude and CVC compared to PCV. Our data suggest that the central respiratory drive, but not the baroreflex or the mechano-electric feedback in the heart, is the main mechanism behind the RSA increase. Hence, differences in RSA and CVC between mechanically ventilated patients might reflect the difference in ventilation mode rather than autonomic impairment. Also, since gas exchange did not increase from PCV to PSV, it is questionable whether RSA has any significance in improving ventilation/perfusion matching during MV

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More information

Published date: 29 February 2012
Keywords: medical physics, biological physics
Organisations: Signal Processing & Control Grp

Identifiers

Local EPrints ID: 334948
URI: https://eprints.soton.ac.uk/id/eprint/334948
ISSN: 0967-3334
PURE UUID: 5678d8a0-bcd9-42a1-9510-4fbdccffb3d1

Catalogue record

Date deposited: 08 Mar 2012 11:39
Last modified: 18 Jul 2017 06:11

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