Libyan Journal of Medicine ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/zljm20 Effects of inverse ratio ventilation combined with lung protective ventilation on pulmonary function in patients with severe burns for surgery Yan-Chao Yang , Qiao Huai , Shu-Zhen Cui , Xiao-Wei Cao & Bu-Lang Gao To cite this article: Yan-Chao Yang , Qiao Huai , Shu-Zhen Cui , Xiao-Wei Cao & Bu-Lang Gao (2020) Effects of inverse ratio ventilation combined with lung protective ventilation on pulmonary function in patients with severe burns for surgery, Libyan Journal of Medicine, 15:1, 1767276, DOI: 10.1080/19932820.2020.1767276 To link to this article: https://doi.org/10.1080/19932820.2020.1767276 © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. Published online: 22 May 2020. Submit your article to this journal Article views: 367 View related articles View Crossmark data Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=zljm20 LIBYAN JOURNAL OF MEDICINE 2020, VOL. 15, 1767276 https://doi.org/10.1080/19932820.2020.1767276 ARTICLE Effects of inverse ratio ventilation combined with lung protective ventilation on pulmonary function in patients with severe burns for surgery Yan-Chao Yanga, Qiao Huaia, Shu-Zhen Cuia, Xiao-Wei Caob and Bu-Lang Gaoa aDepartment of Anesthesiology, Shijiazhuang First Hospital, Hebei Medical University, Shijiazhuang, Hebei Province, China; bRespiratory Department, Shijiazhuang First Hospital, Hebei Medical University, Shijiazhuang, Hebei Province, China ABSTRACT ARTICLE HISTORY Objective: To investigate the effects of inverse ratio ventilation combined with lung- Received 4 March 2020 protective ventilation on pulmonary function and inflammatory factors in severe burn Accepted 1 April 2020 Populations and Methods patients undergoing surgery. : Eighty patients with severe burns KEYWORDS n undergoing elective surgery were divided randomly into two groups: control (CG, = 40) and Inflammatory factor; thermal experiment (EG, n = 40). The CG had conventional ventilation, whereas the EG were ventilated injury; pulmonary edema; with tidal volume (TV) of 6–8 ml/kg, I (inspiration): E (expiration) of 2:1, and positive end- ventilation–perfusion expiratory pressure (PEEP) 5 cm H2O. The following variables were evaluated before (T0), 1 mismatch; hypoxemia h after start of surgery (T1) and after surgery (T2): oxygenation index (OI), partial pressure of carbon dioxide (PaCO2), TV, peak airway pressure (Ppeak), mean airway pressure (Pmean), PEEP, pulmonary dynamic compliance (Cdyn), alveolar–arterial difference of oxygen partial pressure D(A-a)O2, lactic acid (Lac), interleukin (IL)-6 and IL-10, and lung complications. Results: At T1 and T2 time points, the OI, Pmean and Cdyn were significantly greater in the EG than in the CG while the TV, Ppeak, D(A-a)O2, IL-6 and IL-10 were significantly smaller in the EG than in the CG. At the end of the surgery, the Lac was significantly smaller in the EG than in the CG (1.28 ± 0.19 vs. 1.40 ± 0.23 mmol/L). Twenty-four hours after the surgery, significantly more patients had hypoxemia (27.5 vs. 10.0%), increased expectoration (45.0 vs. 22.5%), increased lung texture or exudation (37.5 vs. 17.5%) in the CG than in the EG. Conclusions: Inverse ratio ventilation combined with lung-protective ventilation can reduce Ppeak, increase Pmean and Cdyn, improve the pulmonary oxygenation function, and decrease ILs in severe burn surgery patients. 1. Introduction injurious stimuli and cause a significantly higher mor- Patients with severe burns are often complicated with tality in patients with severe pulmonary injury or multiple organ dysfunction, and lung dysfunction acute respiratory distress syndrome [7,8]. usually occurs very early with a higher incidence in Thus, the concept of protective ventilation strategies severe burns [1,2]. The greatest challenges in initial has been put forward by application of smaller physiolo- burn management are associated with mechanical gical TVs to minimize alveolar overdistension or repetitive and physiologic alterations caused by severe thermal alveolar collapse and also by application of a higher posi- injury [3,4]. Inflammation response may result in pul- tive end-expiratory pressure (PEEP) to improve oxygena- monary edema, and influx of plasma within the pul- tion [7,9]. Some studies in the general surgery of patients monary parenchyma causes progressing exaggeration with a high risk of postoperative pulmonary complications of ventilation–perfusion mismatch, leading to intra- had reported improved clinical outcomes in patients with pulmonary shunt, alveoli collapse, worsening arterial preoperatively healthy lungs using this protective ventila- oxygenation, impaired gas exchange, and ultimately, tion strategy [10,11]. Blank et al [7]. have proven that a low hypoxemia and rising arterial carbon dioxide (CO2)[5]. TV does not prevent postoperative respiratory complica- Elective surgery for burn wound excision and skin tions without adequate PEEP even though a low TV is an grafting may further cause a series of pathophysiolo- important component of the lung-protective ventilation gical changes and exaggerate pulmonary injury [6]. strategy. Pressure-controlled inverse ratio ventilation has Mechanical ventilation is a crucial supportive been reported to have successfully recruited collapsed approach for critically ill patients or for patients alveoli and improved oxygenation at lower peak airway undergoing major surgical procedures. However, pressure (Ppeak) [9,12–14]. mechanical ventilation with a high tidal volume (TV) Since the use of increased inspiratory time with the may subject the lung to a variety of potentially inspiratory to expiratory ratio (I:E) of over 3:1 may CONTACT Bu-Lang Gao [email protected] Department of Anesthesiology, Shijiazhuang First Hospital, 9 Fangbei Road, Shijiazhuang, Hebei Province 050011, China © 2020 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. 2 Y.-C. YANG ET AL. affect cardiac output, the optimal I:E is set at 2:1 by pressure (D(A-a)O2) and lactic acid value (Lac). The OI some authors [9,15]. It was hypothesized that the was calculated with the formula of OI = PaO2/FiO2 volume-controlled inverse ratio ventilation combined (forced inspiratory oxygen concentration) [17]. The with a protective ventilation strategy with a lower TV following respiratory parameters were also recorded: and a higher PEEP would benefit burn patients with TV, Ppeak, mean airway pressure (Pmean), PEEP, and severe pulmonary injury than a conventional ventila- pulmonary dynamic compliance (Cdyn, equals TV/ tion strategy. This study was consequently performed (Ppeak-PEEP)). Venous blood of 4 ml was obtained at to investigate this hypothesis in a cohort of patients the above time points, stood for 30 min, and was with severe burn injury who underwent elective sur- centrifuged for 5 min at 3000 revolutions gery for burn wound excision and skin grafting under per minute. The supernatant was extracted and general anesthesia. restored at −80 refrigerator for test. The enzyme- linked immunosorbent assay (ELISA) was used to test 2. Populations and methods the level of the interleukins (IL-6 and IL-10). Pulmonary complications were recorded within 48 h This study was approved by the ethics committee of including hypoxemia, increased expectoration, and the hospital with all patients given their written ventilator-assisted breathing, and chest radiography informed consent. All methods were performed in was performed for evaluation of the lung complica- accordance with the relevant guidelines and regula- tions like exudation before and after surgery. tions. Patients with severe burn injury who were undergo elective surgery for burn wound excision 3. Statistical analysis and skin grafting under general anesthesia were enrolled in this study. The inclusion criteria were Statistical analysis was performed using SPSS 23.0 patients aged 26–63 years old, of severe burn (IBM, Chicago, IL, USA). Measurement data were pre- American Society of Anesthesiologists (ASA) [16] sented as mean ±SD (standard deviation) if the data grade II–IV, with a total burned area of over 30%, were in normal distribution. Two-tailed Student’s with a third-degree burned area of over 10% or with t-test was used for comparison between the two inhalation injury. Patients with cardiopulmonary dis- groups. If the measurement data were not in normal eases were not included. All enrolled patients were distribution, median and range were used for descrip- randomly divided into two groups: the experiment tion of the data and tested with the χ2 test. For group (EG, n = 40) and the control group (CG, categorical variables, the χ2 test was applied. n = 40) using a computer generated randomization list. p < 0.05 was set as statistically significant. The size Midazolam 0.04 mg/kg, cisatracurium 0.2 mg/kg, of sample was decided according to the following etomidate 0.3 mg/kg and fentanyl 4 μg/kg were conditions. The primary variable was PaO2 which injected intravenously for induction of anesthesia. had a standard deviation of 37 from our previous After the patient fell asleep, visual laryngoscope was pilot study in 20 patients. Analysis of the priori placed through the mouth, and subsequently the power with the two-sided analysis using the α error endotracheal tube was inserted. Anesthesia was main- of 5% and the power at 95% demonstrated that at tained with propofol 3–5 mg/kg/h, and remifentanil least 46 patients were needed in a two-arm study [18]. hydrochloride was continuously pumped in the dose Thus, 80 patients could well meet the requirements to of 0.1–0.2 μg/kg/min, and sevoflurane was inhaled in. reach a statistically significant difference. All patients were successfully intubated once, and then mechanical ventilation was started.