Electrocardiogram changes during positive pressure breathing in rabbits

Abstract

Positive pressure breathing produced by mechanical ventilation with an expiratory threshold load (ETL) may modify electrocardiogram (ECG) complexes independently of any recording artefact due to lung volume changes. Anaesthetized, paralyzed rabbits were treated for about 2 h, then killed. In intact then vagotomized animals two situations were studied successively. Firstly, positive inspiratory pressure breathing, and secondly, positive inspiratory plus expiratory pressure breathing by adding ETL to mechanical ventilation. Arterial blood gases were measured and held constant throughout the challenge. Oesophageal pressure, giving indirect measurement of intrathoracic pressure, arterial blood pressure, blood flows in abdominal aorta and inferior vena cava and standard ECG recordings were made at baseline condition during mechanical ventilation, then at the end of a 10-min period of ETL breathing. The ETL breathing decreased arterial blood pressure significantly and reduced arterial and venous blood flows in the same proportion. No change in the duration of ECG complexes was noticed. However, ETL markedly reduced the amplitude of P- and T-waves, but not that of R-wave, an effect significantly accentuated after vagotomy. The ETL breathing increased the T-vector angle, with no associated change in QRS vector angle. The present animal investigations revealed that positive pressure breathing modifies the ECG independently of the consequences of ETL-induced lung volume changes. We speculate that the changes in P- and T-wave amplitude may have resulted from a reduced transmural pressure gradient between the epicardium and endocardium.

An adhesive, low swelling and conductive tri-network hydrogel for wearable electronic devices

“…36 Conventional in vitro continuous monitoring devices such as ECGs are often limited by signal artifacts from dynamic noise, and human-generated noise such as breathing cannot be avoided. 37 Compared to processing techniques such as band-pass filtering, which can lead to loss of information, the use of a damped hydrogel minimizes mechanical noise and enables the detection of physiological signals with low noise. 38 The TN hydrogel was applied to the surface of the ECG electrodes for ECG testing (Fig.…”

Effects of Mechanical Ventilation on the Electrocardiogram in Adults

“…The key finding of the present study is that hemodynamically stable patients without active cardiopulmonary disease who are undergoing elective surgery demonstrate relatively minor ECG changes from baseline with the addition of positive-pressure ventilation. A recent study in rabbits [14] on the ECG changes with positive end-expiratory pressure (PEEP) detected reductions in P-wave and Twave amplitudes but no change in HR and only minor decreases in R-wave amplitude. Our study did not specifically analyze P-or T-wave amplitudes, and the amount of PEEP applied in the study by Joulia et al [14] was relatively large compared to the amount used in the present study and what is typically used clinically.…”

“…A recent study in rabbits [14] on the ECG changes with positive end-expiratory pressure (PEEP) detected reductions in P-wave and Twave amplitudes but no change in HR and only minor decreases in R-wave amplitude. Our study did not specifically analyze P-or T-wave amplitudes, and the amount of PEEP applied in the study by Joulia et al [14] was relatively large compared to the amount used in the present study and what is typically used clinically. One interesting finding of the present study is the shift of the mean frontal P-wave axis intraoperatively and resolution postoperatively.…”