Hyperventilation – ABC CARDIOL

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Original Article

Use of a Portable Mechanical Ventilator during Cardiopulmonary Resuscitation is Feasible, Improves Respiratory Parameters, and Prevents the Decrease of Dynamic Lung Compliance

Manoel Ângelo Gomes Palácio et al. Edison Ferreira de Paiva Gustavo Bernardes de Figueiredo Oliveira Luciano César Pontes de Azevedo … Bruno Gregnanin Pedron Elizabete Silva dos Santos Ari Timerman

Abstract

Background

For practical and protective ventilation during cardiopulmonary resuscitation (CPR), a 150-grams mechanical ventilator (VLP2000E) that limits peak inspiratory pressure (PIP) during simultaneous ventilation with chest compressions was developed.

Objectives

To evaluate the feasibility of VLP2000E ventilation during CPR and to compare monitored parameters versus bag-valve ventilation.

Methods

A randomized experimental study with 10 intubated pigs per group. After seven minutes of ventricular fibrillation, 2-minute CPR cycles were delivered. All animals were placed on VLP2000E after achieving return of spontaneous circulation (ROSC).

Results

Bag-valve and VLP2000E groups had similar ROSC rate (60% vs. 50%, respectively) and arterial oxygen saturation in most CPR cycles, different baseline tidal volume [0.764 (0.068) vs. 0.591 (0.123) L, p = 0.0309, respectively] and, in 14 cycles, different PIP [52 (9) vs. 39 (5) cm H₂O, respectively], tidal volume [0.635 (0.172) vs. 0.306 (0.129) L], ETCO₂[14 (8) vs. 27 (9) mm Hg], and peak inspiratory flow [0.878 (0.234) vs. 0.533 (0.105) L/s], all p < 0.0001. Dynamic lung compliance (≥ 0.025 L/cm H₂O) decreased after ROSC in bag-valve group but was maintained in VLP2000E group [0.019 (0.006) vs. 0.024 (0.008) L/cm H₂O, p = 0.0003].

Conclusions

VLP2000E ventilation during CPR is feasible and equivalent to bag-valve ventilation in ROSC rate and arterial oxygen saturation. It produces better respiratory parameters, with lower airway pressure and tidal volume. VLP2000E ventilation also prevents the significant decrease of dynamic lung compliance observed after bag-valve ventilation. Further preclinical studies confirming these findings would be interesting.

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Artigo Original

Ergoreflex activity in heart failure

Juliana Fernanda Canhadas Belli et al. Fernando Bacal Edimar Alcides Bocchi Guilherme Veiga Guimarães

A large body of evidence has suggested the existence of a reflex network that becomes hyperactive secondary to musculoskeletal alterations that occur in heart failure (HF) syndrome. Together with sympathoinhibitory cardiovascular reflexes, suppressed in the presence of the syndrome, heart failure can contribute to physical exercise intolerance. The hyperactivation of signals originated from receptors located in skeletal muscles (mechanoreceptors – metaboreceptors) is a recently proposed hypothesis to explain the origin of fatigue and dyspnea symptoms in HF. In HF, other alterations in the reflex control system, which are not mutually exclusive, contribute to dyspnea. The inappropriate stimulation of the arterial baroreceptors, with the consequent lack of inhibition of the muscle metaboreflex and carotid chemoreflex unloading and the increase in the renal vasoconstriction with angiotensin II release can also be considered. Although the functional alterations of the reflexes were used independently to illustrate the sympathetic excitation observed in HF, the interaction between these reflexes under normal and pathological conditions, especially its contribution to the sympathoexcitatory state found in HF, has not been broadly investigated. Therefore, questions about a possible association between the muscle receptors (mechano and metaboreceptors) in the genesis of the ergoreflex exacerbation, observed in HF, remain. Thus, the objective of this review was to integrate the knowledge on the mechano and metaboreflex (ergoreflex) in HF syndrome, as well as to clarify the influence of HF drug therapy on the ergoreflex.