ABSTRACT
The paper presents the results of a study of the impact of autoPEEP (positive end-expiratory pressure) on gas exchange in the lungs, their biomechanical characteristics, the transport and consumption of oxygen by inverting the inspiration/expiration ratio under the volume-controlled mechanical ventilation of the lung (VCMVL) in patients with acute parenchymatous lung lesion, as well as how to choose the optimum inspiration/expiration ratio in VCMVL by analyzing the pattern of total PEEP (the sum of positioning and autoPEEP) in this group of patients.
Subject(s)
Lung Diseases/physiopathology , Positive-Pressure Respiration, Intrinsic/physiopathology , Positive-Pressure Respiration/methods , Respiratory Mechanics/physiology , Acute Disease , Adult , Aged , Catheterization, Swan-Ganz , Female , Humans , Lung Diseases/complications , Male , Middle Aged , Oxygen/blood , Positive-Pressure Respiration, Intrinsic/etiology , Pulmonary Circulation/physiology , Pulmonary Gas Exchange/physiologyABSTRACT
Mechanical ventilation of the lungs (MVL) with positive end expiratory pressure (PEEP) is difficult in patients with unilateral lung damage because of uneven distribution of volumes and pressures in the involved and intact lungs. Harmful effects are easier manifested under such conditions. Selective MVL with selective PEEP is widely used abroad for optimizing MVL, but this method is rather expensive and is not devoid of shortcomings. Our study carried out in 32 patients with unilateral lung involvement showed that traditional MVL with general PEEP can effectively (in 75% cases) regulate gaseous exchange and decrease its untoward effects if MVL is performed with the patient lying on the healthy side and not supine. MVL in patients with unilateral lung injury lying on the healthy side can be a simpler and cheaper alternative to selective MVL with selective PEEP.
Subject(s)
Drainage, Postural/methods , Lung Injury , Pneumonia/therapy , Positive-Pressure Respiration/methods , Wounds, Nonpenetrating/therapy , Wounds, Penetrating/therapy , Acute Disease , Adult , Aged , Drainage, Postural/statistics & numerical data , Female , Humans , Lung/physiopathology , Male , Middle Aged , Pneumonia/physiopathology , Positive-Pressure Respiration/statistics & numerical data , Wounds, Nonpenetrating/physiopathology , Wounds, Penetrating/physiopathologyABSTRACT
The relationship between the mean pressure in the trachea, generated in mechanical ventilation of the lungs (Ptr.m), and normal arterial oxygenation is linear in ventilated patients with severe bilateral acute parenchymatous damage to the lungs. Under conditions of mechanical ventilation of the lungs (MVL) with regulated volume, constant end-expiratory pressure (PEEP) and inspiratory pause (eIP) are effective methods for regulating Ptr.m. However, the efficacy of regulating Ptr.m by PEEP and IF for each clinical case is different. The algorithm of using PEEP and IF for optimizing the respiratory pattern in this category of patients is not clear, too. The results indicate that optimization of MVL with controlled volume should be started with selecting the optimal level of PEEP for each patient. The level of Ptr.m should not be increased immediately at by of prolonging eIP, because the probability of compromising the hemodynamics is higher in such a case than the probability of improving blood oxygenation. Only after selecting the optimal PEEP is it permissible to try to improve arterial oxygenation by prolonging xx, because under such conditions the efficacy of prolonged inspiration is notably increased. Our data indicate that eIP no higher than 30% of the respiratory cycle (inspiration/expiration = 1.5/1) is the optimal. A further increase of eIP gives rise to a tendency towards decrease of arterial oxygenation and oxygen transport to tissues.
