Hemodynamic, ventilatory and gasometric evaluation of an experimental bronchopleural fistula

PetCO2, VCO2 and CorPP Values in the Successful Prediction of the Return of Spontaneous Circulation: An Experimental Study on Unassisted Induced Cardiopulmonary Arrest

Introduction

During cardiac arrest, end-tidal CO₂ (PetCO₂), VCO₂ and coronary perfusion pressure fall abruptly and tend to return to normal levels after an effective return of spontaneous circulation. Therefore, the monitoring of PetCO₂ and VCO₂ by capnography is a useful tool during clinical management of cardiac arrest patients.

Objective

To assess if PetCO₂, VCO₂ and coronary perfusion pressure are useful for the prediction of return of spontaneous circulation in an animal model of cardiac arrest/cardiopulmonary resuscitation treated with vasopressor agents.

Methods

42 swine were mechanically ventilated (FiO₂=0.21). Ventricular fibrillation was induced and, after 10 min, unassisted cardiac arrest was initiated, followed by compressions. After 2 min of basic cardiopulmonary resuscitation, each group received: Adrenaline, Saline-Placebo, Terlipressin or Terlipressin + Adrenaline. Two minutes later (4^th min of cardiopulmonary resuscitation), the animals were defibrillated and the ones that survived were observed for an additional 30 min period. The variables of interest were recorded at the baseline period, 10 min of ventricular fibrillation, 2^nd min of cardiopulmonary resuscitation, 4^th min of cardiopulmonary resuscitation, and 30 min after return of spontaneous circulation.

Results

PetCO₂ and VCO₂ values, both recorded at 2 min and 4 min of cardiopulmonary resuscitation, have no correlation with the return of spontaneous circulation rates in any group. On the other hand, higher values of coronary perfusion pressure at the 4th min of cardiopulmonary resuscitation have been associated with increased return of spontaneous circulation rates in the adrenaline and adrenaline + terlipressin groups.

Conclusion

Although higher values of coronary perfusion pressure at the 4th min of cardiopulmonary resuscitation have been associated with increased return of spontaneous circulation rates in the animals that received adrenaline or adrenaline + terlipressin, PetCO₂ and VCO₂ have not been shown to be useful for predicting return of spontaneous circulation rates in this porcine model.

Evaluation of the Efficiency of the Atraumatic Endotracheal Tube in the Pulmonary-Gas Exchange: an Experimental Study

OBJECTIVE

Mechanical ventilation is frequently necessary, in which case the use of an endotracheal tube is mandatory. The tube has an inflatable balloon in its distal extremity, whose aim is, among other functions, an efficient arterialization. However, serious injuries in the place of contact of the balloon with the trachea can be frequent. Some studies point out that balloons with permanent pressure may reduce this complication. Nevertheless, air scape, expressed by the inspiratory (IV) and expiratory volume (EV) variation (Δ IV-EV), may occur, possibly leading to hypoxemia. Thus, the goal of this study was to verify the efficiency of a modified endotracheal tube on arterializations compared to the traditional endotracheal tube.

METHODS

The modified endotracheal tube presents intermittent insufflation, with three drillings in the internal region of the cuff, allowing for insufflation in the inspiratory phase of the mechanical ventilation. Three animals were used for the control group, with a cuff pressure of 30 cmH₂O, and seven pigs had the modified endotracheal tube. Each animal was kept under mechanical ventilation (FIO₂=0.21) for 6 hours. Arterial and venous gases were measured every three hours (T₀; T₃; T₆).

RESULTS

The gases confirmed the lack of hypoxia between the Groups, with a difference in the ΔIV-EV at T0 (P=0.0486).

CONCLUSIONS

In this study, the lack of hypoxia showed the efficiency of the modified endotracheal tube. However, new studies are necessary, particularly in diseased lungs, in order to evaluate the real efficiency of the mentioned device on the pulmonary gas exchange.

Adjustable inspiratory occlusion valve in experimental bronchopleural fistula. A new therapeutic perspective

PURPOSE

To assess the efficacy of an adjustable inspiratory occlusion valve in experimental bronchopleural fistula during mechanical ventilation.

METHODS

We studied six mechanically ventilated pigs in a surgically created, reproducible model of bronchopleural fistula managed with mechanical ventilation and water-sealed thoracic drainage. An adjustable inspiratory occlusion valve was placed between the thoracic drain and the endotracheal tube. Hemodynamic data, capnography and blood gases were recorded before and after the creation of the bronchopleural fistula as well as after every adjustment of the inspiratory occlusion valve.

RESULTS

When compared with the standard water-sealed drainage treatment, the use of an adjustable inspiratory occlusion valve improved the alveolar tidal volume and reduced bronchopleural air leak (p<0.001), without hemodynamic compromise when compared with conventional water sealed drainage.

CONCLUSION

The use of an adjustable inspiratory occlusion valve improved the alveolar tidal volume, reduced alveolar leak, in an experimental reproducible model of bronchopleural fistula, without causing any hemodynamic derangements when compared with conventional water sealed drainage.