This is a clinical trial that was performed on eligible 40 patients undergoing CABG surgery referred to the ICU wards of the open heart and heart surgery of Razi Hospital in Birjand/Iran in 2020. Inclusion criteria included no severe lung disease, neuromuscular and cognitive impairment, or renal impairment, no emergency surgery, mechanical ventilation<24 hours, ability to perform breathing exercises and use incentive spirometry. Exclusion criteria also included the need for reoperation due to possible complications, death or transfer of patient to another hospital, the occurrence of severe hemodynamic disorders (such as severe decrease or increase in blood pressure, shock) during the intervention, complications affecting hemodynamic changes such as bleeding and unwillingness to continue participating in the study.
The sample size was estimated 20 people per group based on a similar study [9] taking into account test power of 80% and a confidence interval of 90%. Eligible patients were gradually enrolled in the study using convenience sampling method and divided into two groups of 20 and received the desired intervention through a quadruple block with a 1: 1 allocation ratio.
Procedure
After obtaining the necessary permissions and access to the samples, the demographic form was completed for the patients and the day before the surgery, the DBE patients were taught deep breathing exercises and the patients in the incentive spirometry group were asked how to use the incentive spirometry in practice at the patient's bedside. The performance of each patient was then evaluated. This training was conducted by the second author, who has a master's degree in medical surgery nursing and has five years of experience working in the ICU.
DBEs were planned in such a way that the patient was first placed in a sitting or semi-sitting position. The patient then took deep, slow nasal breaths while placing his or her hands on his or her chest for easier breathing and pain relief, and applying gentle pressure. At the end-inhale phase, the patient was asked to hold his/her breath for three seconds and then exhale through the mouth while the lips and abdominal muscles were compressed [15]. DBEs were repeated ten times with two-hour interval when the patient woke up under the supervision of the second author.
In the incentive spirometry group, the patient was first placed in a sitting or semi-sitting position and performed the inhalation inside the device by placing an incentive spirometer tube in the mouth. At the end of the inhalation, the patient was asked to hold his/her breath for three seconds and exhale slowly through the mouth by removing the device. Patients were also instructed that they could gradually take deeper breaths with each increase in ball lifting [16]. These exercises were repeated in the form of 10 deep breaths, every two hours during awakening under the supervision of the second author.
These interventions started one hour after removal of the endotracheal tube under the supervision of the researcher and continued until three days later. Before the intervention, on the first, second and third days, hemodynamic indices, including SBP and DBP, heart rate (HR), arterial SaO2, and RR were evaluated for patients in both groups and the results were recorded in the relevant form. It should be noted that on average, respiratory physiotherapy was performed routinely in the hospital, one hour after extubation.
Data collection tools
Demographic data were collected using demographic form, including information on sex, age, level of education, marital status, smoking, history of hypertension, diabetes, and hyperlipidemia. In order to assess the content validity of the questionnaire, it was given to ten faculty members and their views were implemented.
To record hemodynamic indices, a form including information on hemodynamic indices such as SBP and DBP, HR, arterial SaO2, and RR was used. Blood pressure was measured a hand-held sphygmomanometer according to the guidelines of the World Health Organization. For this purpose, a hand-held sphygmomanometer with an armband of appropriate size was used while the patient was in semi-setting position on the bed and his hand was at the heart level. It was measured twice with 10-15 min interval and the average of two measurements was recorded as blood pressure. The first and fifth Korotkoffs were considered as SBP and DBP. Pulse oximetry was used to measure HR and arterial blood SaO2. RR was counted by observing chest movements per minute. The devices were calibrated before the research.
Data Analysis
First, the data distribution was investigated using Kolmogorov-Smirnov test, and the results showed that all research variables had a normal distribution (p>0.05). Data analysis was then carried out using descriptive statistics such as mean and standard deviation and inferential statistics such as Independent t-test, chi-square or Fisher's exact test and Repeated measures ANOVA in SPSS ver. 16. P-value<0.05 was considered as the significance level in all tests.