Key result
Controlled intermittent positive pressure mechanical ventilation under anaesthesia generates respiratory sinus arrhythmia via non-neural mechano-electric feedback rather than central vagal modulation.
Why the study?
How does intermittent positive pressure mechanical ventilation affect respiration-related cardiovascular oscillations compared to spontaneous breathing?
How does intermittent positive pressure mechanical ventilation affect respiration-related cardiovascular oscillations compared to spontaneous breathing?
Interpretative paradigms of respiration-related cardiovascular oscillations derived from spontaneously breathing subjects should not be applied to patients undergoing mechanical ventilation.
Answers are grounded in this paper and cite their sources.
Interpretative paradigms from spontaneous breathing should not apply to mechanical ventilation; challenges central vagal assumptions in respiration-cardiovascular research.
The vast majority of the available literature regarding cardiovascular oscillations refers to spontaneously breathing subjects. Only a few studies investigated cardiovascular oscillations, and especially respiration-related ones (RCVO), during intermittent positive pressure mechanical ventilation (IPPV) under anaesthesia. Only a handful considered assisted IPPV, in which spontaneous breathing activity is supported, rather than replaced as in controlled IPPV. In this paper, we review the current understanding of RCVO physiology during IPPV, from literature retrieved through PubMed website. In particular, we describe how during controlled IPPV under anaesthesia respiratory sinus arrhythmia appears to be generated by non-neural mechano-electric feedback in the heart (indirectly influenced by tonic sympathetic regulation of vascular tone and heart contractility) and not by phasic vagal modulation of central origin and/or baroreflex mechanisms. Furthermore, assisted IPPV differs from controlled IPPV in terms of RCVO, reintroducing significant central respiratory vagal modulation of respiratory sinus arrhythmia. This evidence indicates against applying to IPPV interpretative paradigms of RCVO derived from spontaneously breathing subjects, and against considering together IPPV and spontaneously breathing subjects for RCVO-based risk assessment. Finally, we highlight the opportunities that IPPV offers for future investigations of RCVO genesis and interactions, and we indicate several possibilities for clinical applications of RCVO during IPPV.
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Beda et al. (2011) conducted a review in Respiration-related cardiovascular oscillations during anaesthesia. Intermittent positive pressure mechanical ventilation (IPPV) vs. Spontaneous breathing was evaluated. Controlled intermittent positive pressure mechanical ventilation under anaesthesia generates respiratory sinus arrhythmia via non-neural mechano-electric feedback rather than central vagal modulation.
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