Breathing cardiovascular variability and baroreflex in mechanically ventilated patients

2008 ◽  
Vol 295 (6) ◽  
pp. R1934-R1940 ◽  
Author(s):  
Andry Van de Louw ◽  
Claire Médigue ◽  
Yves Papelier ◽  
François Cottin

Heart rate and blood pressure variations during spontaneous ventilation are related to the negative airway pressure during inspiration. Inspiratory airway pressure is positive during mechanical ventilation, suggesting that reversal of the normal baroreflex-mediated pattern of variability may occur. We investigated heart rate and blood pressure variability and baroreflex sensitivity in 17 mechanically ventilated patients. ECG (RR intervals), invasive systolic blood pressure (SBP), and respiratory flow signals were recorded. High-frequency (HF) amplitude of RR and SBP time series and HF phase differences between RR, SBP, and ventilatory signals were continuously computed by Complex DeModulation (CDM). Cross-spectral analysis was used to assess the coherence and the gain functions between RR and SBP, yielding baroreflex sensitivity indices. The HF phase difference between SBP and ventilatory signals was nearly constant in all patients with inversion of SBP variability during the ventilator cycle compared with cycling with negative inspiratory pressure to replicate spontaneous breathing. In 12 patients ( group 1), the phase difference between RR and ventilatory signals changed over time and the HF-RR amplitude varied. In the remaining five patients ( group 2), RR-ventilatory signal phase and HF-RR amplitude showed little change; however, only one of these patients exhibited a RR-ventilatory signal phase difference mimicking the normal pattern of respiratory sinus arrhythmia. Spectral coherence between RR and SBP was lower in the group with phase difference changes. Positive pressure ventilation exerts mainly a mechanical effect on SBP, whereas its influence on HR variability seems more complex, suggesting a role for neural influences.

Spinal Cord ◽  
2015 ◽  
Vol 53 (11) ◽  
pp. 839-840
Author(s):  
L Malmqvist ◽  
T Biering-Sørensen ◽  
K Bartholdy ◽  
A Krassioukov ◽  
K-L Welling ◽  
...  

Author(s):  
Antoine Vieillard-Baron

Knowledge of heart–lung interactions is key to manage haemodynamics in mechanically ventilated patients (see also Chapter 5). It allows intensivists to understand the meaning of blood and pulse pressure respiratory variations (PPV). Unlike spontaneous breathing, positive pressure ventilation increases blood pressure and pulse pressure during inspiration following by a decrease during expiration. This is called reverse pulsus paradoxus and includes a ‘d-down’ and a ‘d-up’ effect. No variation means no effect of mechanical ventilation on the heart and especially on the right heart. In case of significant PPV, tidal volume usually reduces right ventricular stroke volume by way of reducing preload where systemic venous return is decreased (fluid expansion is useful to restore haemodynamics, when impaired) or increasing afterload (obstruction of pulmonary capillaries due to alveolar inflation and, in this case, fluid expansion is useless or even sometimes deleterious). Clinical examination as well as evaluation of respiratory variations of superior vena cava by echo, helps to distinguish between these two situations. By studying the beat-by-beat changes in echo parameters induced by positive pressure ventilation heartbeat by heartbeat, echocardiography is perfectly suited to study heart–lung interactions and then to propose an appropriate optimization in case of haemodynamic impairment.


1995 ◽  
Vol 4 (3) ◽  
pp. 233-238 ◽  
Author(s):  
LL Chlan

BACKGROUND: Although mechanically ventilated patients experience numerous stressors, they have not been included in music therapy stress reduction and relaxation studies. OBJECTIVE: To examine selected psychophysiologic responses of mechanically ventilated patients to music. METHODS: A two-group experimental design with pretest, posttest, and repeated measures was used. Twenty mechanically ventilated patients were randomized to a music-listening group or a nonmusic (headphones only) group. Physiologic dependent measures--heart rate and rhythm, respiratory rate, systolic and diastolic blood pressure, oxygen saturation, and airway pressure--were collected at timed intervals. Psychologic data were collected before and after intervention using the Profile of Mood States. RESULTS: Using repeated measures analysis of variance, results for heart rate and respiratory rate over time and over time between groups were significant. Between-group differences were significant for respiratory rate. Significant differences were found via t test for the music group's Profile of Mood States scores. No adverse cardiovascular responses were noted for either group. CONCLUSIONS: Data indicated that music listening decreased heart rate, respiratory rate, and Profile of Mood States scores, indicating relaxation and mood improvement.


1995 ◽  
Vol 23 (2) ◽  
pp. 175-177 ◽  
Author(s):  
P. V. Van Heerden ◽  
W. Jacob ◽  
P. D. Cameron ◽  
S. Webb

Segmental and lobar pulmonary atelectasis is a common occurrence in mechanically ventilated patients. Standard therapy for atelectasis relies on positive pressure ventilation, positive end expiratory pressure (PEEP), tracheobronchial toilet and regular chest physiotherapy. Various adjuncts to physiotherapy such as bronchoscopic clearance of secretions have not proved to be of additional benefit. Bronchoscopic clearance of secretions followed by insufflation of room air at 30 cm H2O into the atelectatic segment was employed on ten occasions in mechanically ventilated patients. Rapid re-expansion of the collapsed segment or lobe occurred in seven out of the ten treatments.


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