Concomitant ventilatory and circulatory functions of the diaphragm and abdominal muscles

Abstract

Expulsive maneuvers (EMs) caused by simultaneous contraction of diaphragm and abdominal muscles shift substantial quantities of blood from the splanchnic circulation to the extremities. This suggests that the diaphragm assisted by abdominal muscles might accomplish ventilation and circulation simultaneously by repeated EMs. We tested this hypothesis in normal subjects by measuring changes (Δ) in body volume (Vb) by whole body plethysmography simultaneously with changes in trunk volume (Vtr) by optoelectronic plethysmography, which measures the same parameters as whole body plethysmography plus the volume of blood shifts (Vbs) between trunk and extremities: Vbs = ΔVtr-ΔVb. We also measured abdominal pressure, pleural pressure, the arterial pressure wave, and cardiac output (Qc). EMs with abdominal pressure ~100 cmH(2)O for 1 s, followed by 2-s relaxations, repeated over 90 s, produced a "stroke volume" from the splanchnic bed of 0.35 ± 0.07 (SD) liter, an output of 6.84 ± 0.75 l/min compared with a resting Qc of 5.59 ± 1.14 l/min. Refilling during relaxation was complete, and the splanchnic bed did not progressively empty. Diastolic pressure increased by 25 mmHg during each EM. Between EMs, Qc increased to 7.09 ± 1.14 l/min due to increased stroke volume and heart rate. The circulatory function of the diaphragm assisted by simultaneous contractions of abdominal muscles with appropriate pressure and duration at 20 min(-1) can produce a circulatory output as great as resting Qc, as well as ventilation. These combined functions of the diaphragm have potential for cardiopulmonary resuscitation. The abdominal circulatory pump can act as an auxiliary heart.

Network of Breathing. Multifunctional Role of the Diaphragm: A Review

“…Furthermore, the most of others parameters of the cardiac function such as ejection fraction, aortic pressure, and pulmonary arterial pressure, preload and afterload and even tissue oxygenation have been shown to be modelocked to breathing [43,44]. Diaphragmatic contractions also increase cardiac output under conditions of preload dependency, which has actually been observed in healthy humans [45] and in patients with cardiac pacemakers, in whom diaphragmatic contractions were induced via the pacemaker [46]. Interestingly, D'Alonzo and Krachman have also shown that poor diaphragm biomechanics may lead to decreased cardiac output [47].…”

“…A recent study conducted by Aliverti et al [45,48] demonstrated that the modulation of the splanchnic vascular bed as a result of an increase in intraabdominal pressure via diaphragmatic contraction contribute to inferior vena cava blood return, that is, during inspiration, splanchnic venous return is favoured, whereas, during expiration, a venous return of femoral blood flow below the entry of the hepatic vein is preferred. The consequence is that abdominal breathing promotes an extra blood volume mobilisation (from splanchnic circulation) increasing net venous return to inferior vena cava, that is, diaphragmatic inspiration implies that inferior vena cava venous return is facilitated primarily by the central translocation of blood from the vessels of the abdomen and is not the result of facilitation of venous return from the lower limbs [49].…”

“…The consequence is that abdominal breathing promotes an extra blood volume mobilisation (from splanchnic circulation) increasing net venous return to inferior vena cava, that is, diaphragmatic inspiration implies that inferior vena cava venous return is facilitated primarily by the central translocation of blood from the vessels of the abdomen and is not the result of facilitation of venous return from the lower limbs [49]. Thus, a greater diaphragm contraction contributed to abdominal circulatory pump results in haemodynamic benefits secondary to net increase in blood venous return and, through FrankStarling mechanism, greater cardiac stroke volume [45,48]. It should be also mentioned that during inhalation, the inferior vena cava diameter decreases [50] and the efficiency of venous drainage reaches its climax in slow and deep respiration [51].…”

Comparison of different levels of positive expiratory pressure on chest wall volumes in healthy children and patients with fibrosis

“…All individuals were positioned in seated position on a backless bench and centralized in a system of six cameras previously calibrated according to the manufacturer's recommendations and previously published studies [24][25][26] . Subjects were requested to remain motionless breathing freely for 180 seconds.…”

Efeitos do alongamento da musculatura respiratória com a técnica de alongamento passivo e contração-relaxamento na mecânica ventilatória e capacidade funcional de pacientes com doença pulmonar obstrutiva crônica

“…Este método não possui diferenças significativas nos dados quando comparados com outros métodos de diagnóstico da mecânica toracoabdominal (Aliverti, 2008;Layton et al, 2013). É possível mensurar a cada ciclo respiratório, variáveis de volume e de tempo dos três compartimentos da parede torácica e dos dois hemitórax, além das variáveis de assincronia toracoabdominal (Romagnoli et al, 2008;Aliverti et al, 2010;Boudarham et al, 2013). Por todas essas razões o POE tem ganhado grande destaque nos últimos anos, nas pesquisas sobre a mecânica toracoabdominal, mas por ser uma tecnologia recente ainda carece de mais estudos.…”