Aplicaciones e implicaciones de la pausa al final de la inspiración en ventilación mecánica / Applications and implications of end-inspiratory pause in mechanical ventilation / Aplicações e implicações da pausa ao final da inspiração na ventilação mecânica

Resumen: El uso de la pausa al final de la inspiración (PFI) en ventilación mecánica data de hace más de 50 años y con mayor impulso en la década de los 70, se le atribuye una mejoría en la presión parcial de oxígeno arterial (PaO2) al incrementar la presión media de la vía aérea (Pma), mayor aclaramiento de la presión parcial de dióxido de carbono arterial (PaCO2) y permite la monitorización de la presión meseta (Pmeseta) en la mecánica ventilatoria; sin embargo, los estudios clínicos sobre su uso son escasos y controversiales. En este artículo se abordan los mecanismos fisiológicos, fisiopatológicos y la evidencia sobre el uso de la PFI en ventilación mecánica (VM).

Abstract: The use of the end inspiratory pause (EIP) in mechanical ventilation has been going on for more than 50 years and with greater momentum in the 1970s, an improvement in the partial pressure of arterial oxygen (PaO2) is attributed to the increase mean airway pressure, greater clearance of partial pressure of arterial carbon dioxide and allows monitoring of plateau pressure in ventilatory mechanics; However, the Clinical studies on its use are few and controversial. This article addresses the physiological and pathophysiological mechanisms and the evidence on the use of EIP in mechanical ventilation.

Resumo: A utilização da pausa ao final da inspiração (PFI) na ventilação mecânica remonta a mais de 50 anos e com maior impulso na década de 70, atribui-se uma melhora na pressão parcial de oxigênio arterial (PaO2) pelo aumento da pressão média das vias aéreas (Pma), uma maior depuração da pressão parcial de dióxido de carbono arterial (PaCO2) e permite a monitorização da pressão de platô (Pplateau) na mecânica ventilatória, porém estudos Os dados clínicos sobre seu uso são escassos e controversos. Este artigo aborda os mecanismos fisiológicos e fisiopatológicos e as evidências sobre o uso do PFI na ventilação mecânica (VM).

The Effects of Inspiratory Pause on Airway Pressure and Gas Exchange under Same I: E ratio in Volume-controlled Ventilation / 결핵

BACKGROUND: In volume-controlled ventilation, the use of inspiratory pause increases the inspiratory time and thus increases mean airway pressure and improves ventilation But under the same I : E ratio, the effects of in spiratory pause on mean airway pressure and gas exchange are not certain. Moreover, the effects may be different according to the resistance of respiratory system. So we studied the effects of inspiratory pause on airway pressure and gas exchange under the same I : E ratio in volume-controlled ventilation. METHODS: Airway pressure and arterial blood gases were evaluated in 12 patients under volume-controlled mechanical ventilation with and without inspiratory pause time 5%. The I : E ratio of 1 : 3, FiO2, tidal volume, respiratory rate, and PEEP were kept constant. RESULTS: PaCO2 with inspiratory pause was lower than without inspiratory pause (38.6 +/- 7.4 mmHg vs.41.0 +/- 7.7 mmHg. p < 0.01). p(A-a)O2 was not different between ventilation with and without inspiratory pause (185.3 +/- 86.5mm Hg vs. 184.9 +/- 84.9mmHg vs. p=0.766). Mean airway pressure with inspiratory pause was higher than without inspiratory pause (9.7 +/- 4.0 cmH2O vs. 8.8 +/- 4.0 cm H2O, p < 0.01). The resistance of respiratory system inversely correlated with the pressure difference between plateau pressure with pause and peak inspiratory pressure without pause (r=-0.777, p < 0.01), but positively correlated with the pressure difference between peak inspiratory pressure with pause and peak inspiratory pressure without pause (r=0.811, p < 0.01). Thus the amount of increase in mean airway pressure with pause positively correlated with the resistance of respiratory system (r=0.681, p < 0.05). However, the change of mean airway pressure did not correlated with the change of PaCO2. CONCLUSION: In volume-controlled ventilation under the same I : E ratio of 1 : 3, inspiratory pause time of 5% increases mean airway pressure and improves ventilation. Although the higher resistance of respiratory system, the more Increased mean airway pressure, tile increase in mean airway pressure did not correlated with the change in PaCO2.

Effects of Cardiovascular System and Arterial Blood Gas following Respinatory Pattern in One-Lung Ventilation and Pulmonary Edema / 대한마취과학회지

Nowadays the importance of respiratory therapy is increasing with the development of modern medicine. Especially effective respiratory care in the field of anesthesia and intensive care unit has close relationship to the decrease of mortality or morbidity of the critically ill patients. Compared with spontaneous respiration, so various physiological changes related to these methods can occur. Because most modernized ventilations can choose the various respiratory patterns according to the patients' respiratory condition, it is ideal to select the respiratory mode which is least hazardous and most effective to the patients. To confirm the effects of respiratory therapy on the cardiovascular system and arterial blood gas in one-lung ventilation and in pulmonary edema, we made one-lung ventilation by deep right endobronchial intubation and ppulmonary edema was induced by oleid acid (0.05g/kg. IV) to 12 mongrel dogs. And we observed the cardiovascular changes and arterial blood gas analysis in the situation of applying the inspiratory pause(0.25sec. and 0.5sec) and positive end-expiratory pressure(5cm H2O and 10cm H2O). The results were as follows: 1) One-lung Ventilation. (i) Inspiratory pause-There were no changes of cardiovascular system and arterial blood gas in the inspiratory pause of 0.25 and 0.5 sec. (ii)PEEP-In 5cmH2O of PEEP there was no change of cardiovascular system, but there was decrease in PCO2(p<0.01) on arterial blood gas. In 10cmH2O of PEEP there was increase in heart rate(p<0.05) and decrease in cardiac output(p<0.05). There was decrease in PCO2(p<0.01), but there were no changes of pH and PO2 on arterial blood gas. 2) Pulmonary edema. (i) Inspiratory pause-There was increase in heart rate(p<0.01), but there was no change of arterial blood gas in the 0.25 and 0.5sec. inspiratory pause. (ii) PEEP- In 5cmH2O PEEP there was increase in heart rate(p<0.01), but there was no change of arterial blood gas in the 0.25 and 0.5 sec. inspiratory pause. In 10cmH2O PEEP there were decrease in sBP, dBP, MAP, increase in heart rate(p<0.05) and decrease in cardiac output(p<0.01). There were increase in pH(p<0.05) and PO2(p<0.01), decrease in PCO2. According to the above results in the condition of one-lung ventilation mechanical ventilation with inspiratory pause(0.25 or 0.5 sec) was not helpful to respiratory care. 5cmH2O PEEP could improve the pulmonary ventilation without ay changes of cardiovascular system, but 10cmH2O PEEP increased heart rate and decrease cardiac output. In the condition of pulmonary edema, mechanical ventilation with inspiratory pause(0.25 or 0.5 sec) could not improve the pulmonary ventilation with depression of cardiovascular system. PEEP (5 or 10 cmH2O) could improve the pulmonary condition in proportion to PEEP, but it also depressed the cardiovascular system. Therefore we concluded that mild degree PEEP (5cmH2O) may be helpful to the one-lung ventilation or pulmonary edema.