Sigh maneuver protects healthy lungs during mechanical ventilation in adult Wistar rats

Abstract

<jats:p> Mechanical ventilation (MV) is a tool used for the treatment of patients with acute or chronic respiratory failure. However, MV is a non-physiological resource, and it can cause metabolic disorders such as release of pro-inflammatory cytokines and production of reactive oxygen species. In clinical setting, maneuvers such as sigh, are used to protect the lungs. Thus, this study aimed to evaluate the effects of sigh on oxidative stress and lung inflammation in healthy adult Wistar rats submitted to MV. Male Wistar rats were divided into four groups: control (CG), mechanical ventilation (MVG), MV set at 20 sighs/h (MVG20), and MV set at 40 sighs/h (MVG40). The MVG, MVG20, and MVG40 were submitted to MV for 1 h. After the protocol, all animals were euthanized and the blood, bronchoalveolar lavage fluid, and lungs were collected for subsequent analysis. In the arterial blood, MVG40 presented higher partial pressure of oxygen and lower partial pressure of carbon dioxide compared to control. The levels of bicarbonate in MVG20 were lower compared to CG. The neutrophil influx in bronchoalveolar lavage fluid was higher in the MVG compared to CG and MVG40. In the lung parenchyma, the lipid peroxidation was higher in MVG compared to CG, MVG20, and MVG40. Superoxide dismutase and catalase activity were higher in MVG compared to CG, MVG20, and MVG40. The levels of IL-1, IL-6, and TNF in the lung homogenate were higher in MVG compared to CG, MVG20, and MVG40. The use of sigh plays a protective role as it reduced redox imbalance and pulmonary inflammation caused by MV. </jats:p>

Effect of an ionic antineoplastic agent Cytoreg on blood chemistry in a Wistar rat model

“… 12 In our study, we obtained an average pO 2 value of 81.6 ± 7.97 mmHg before treatment with Cytoreg, with post-treatment values of 94.1 ± 19.3 and 147.3 ± 9.59 mmHg at T30’ and T60’, respectively ( Figure 1C ). Comparing these values with reported data for Wistar rats in similar studies, in which the lowest pO 2 was 51 mmHg, 16 with the ranges reported in Table 1 , the rats present a state of normoxia at the start of our study, 14 16 and then exhibit significant increases ( P < 0.05) at T30’ and T60’ post-treatment. Quantitation of the hemoglobin content reveals a slight decline post-treatment, with values of 13.16 ± 2.31, 11.5 ± 2.52, and 11.6 ± 1.49 g/dL at T0’, T30’, and T60’, respectively.…”

“…Our data are comparable with those from other studies on the same species and strain of rat ( Table 1 ). 12 13 14 15 16 The average pH values determined at T0’ (pre-treatment), T30’, and T60’ are 7.45 ± 0.046, 7.25 ± 0.11, and 7.22 ± 0.09, respectively ( Figure 1A ). Values which differ significantly from the initial pH (T0’) ( P < 0.05) are still within the tolerated range for the organism, since they can be compensated by physiological buffers.…”

Different Tidal Volumes May Jeopardize Pulmonary Redox and Inflammatory Status in Healthy Rats Undergoing Mechanical Ventilation

“…Tidal volume was measured by the table spirometer (ADInstruments, Dunedin, New Zealand). The signal was amplified and analyzed using the PowerLab software (ADInstruments, Dunedin, New Zealand) [21].…”

“…At the end of MV, a 200 μL blood sample was collected directly from the right femoral artery using a heparinized syringe (Monovette®, Sarstedt, Germany) for arterial blood gas analysis by the PRIME + ® VET gasometer (Nova Biomedical Corporation, Waltham, MA, USA). The animals were euthanized by an overdose of ketamine (130 mg/kg) and xylazine (0.3 mg/kg) [21].…”

“…Briefly, 100 cells were counted per slide under an optical microscope at 100x magnification. Two domain researchers double-blindly counted unidentified slides at different occasions [21].…”