[Effect of the inhalation ++ anesthetic isoflurane on heart electrophysiology]. / Efecto del anestésico inhalatorio isoflurano sobre la electrofisiología cardíaca.

In two groups, A and B, both composed of 10 mongrel dogs, we studied the cardiac electrophysiologic effects of 1 and 1.5 MAC isoflurane administered by liquid injection in a closed circuit. In group B the study was done under pharmacological autonomic blockade (AB). With electrode catheters for programmed pacing and endocavitary potential recordings, we determined during the anesthesia with 1 and 1.5 MAC isoflurane: RR, spontaneous and paced AH, and HV intervals, corrected sinus recovery time (CSRT), Wenckebach point (WP), functional and effective refractory periods of atria (AFRP, AERP) and AV node (AVNFRP, AVNERP), and ventricular effective refractory period (VERP), these were compared to the ones obtained with a previous thiopental control. In group A, 1 MAC isoflurane increased over control: AERP and AH interval (p < 0.05), AFRP (p < 0.005), RR and AH paced intervals, WP, AVNFRP and VERP (p < 0.001), adding to these CSRT (p < 0.01) in 1.5 CAM. This level did not show differences with 1 MAC. In group B, 1 MAC isoflurane increased over control: AH (p < 0.05), RR, paced AH intervals, WP and AVNFRP (p < 0.001), adding to these AFRP and AERP (p < 0.05) in 1.5 MAC. This level increased with regard to 1 MAC: AFRP, AERP, AH paced interval and AVNERP (p < 0.05), and AVNFRP (p < 0.005). Isoflurane alone or with AB increased parameters of sinusal automaticity, atrial refractoriness, AV nodal conduction and refractoriness, increasing only without AB ventricular refractoriness and CSRT. With AB atrial and AV nodal refractoriness increased in an anesthetic depth dependent way.

[Monitoring of mechanical ventilation during IPPV: implications due to the intrapulmonary entrapment of gas. Study on a physical model of the lung]. / Monitorización de la mecánica ventilatoria durante IPPV: implicaciones debidas al atrapamiento intrapulmonar de gas. Estudio sobre modelo físico de pulmón.

This work was undertaken to determine the possible influence of gas trapping on the values of total respiratory system compliance and on the air flow resistance at the air ways obtained by conventional effects of positive telespiratory alveolar pressure (auto-PEEP) typical of gas trapping on ventilatory dynamics. This study has been carried out in a physical model of the lung. The results support the contention that in the above situation: 1) the total compliance of the respiratory system measured as the quotient between the current volume and the plateau pressure (C.DIN) shows lower values than those of the static compliance (C.EST), and 2) flow resistance at the air ways must be measured as the quotient between the time constant and the plateau pressure. It should not be measured as the quotient between the time constant and the static compliance since in that case the values would be lower than the real ones.