a. Study population, sampling and research design
This interventional research (before and after) is a parallel clinical trial study, not blinded and non-randomized. That has been registered in the Iranian Clinical Trial Center (17.01.2021; IRCT20201010048981N1). In this study, we could not perform randomization because we found that only one of the hospitals that not affiliated with our university used the closed type and it was their routine and the other hospitals did not use it currently. Eligible patients were selected to enter the study and Allocation of the participants was done non-randomly in two intervention and control groups. This study was started after obtaining permission from the ethics committee (IR.AJUMS.REC.1399.229). Relatives or companions of all patients were informed about the nature of the study and entered the study with their consent, and they had the right to withdraw from the study at any time during the research.
Inclusion criteria were admission to the intensive care unit, age above 18 years, absence of acquired immunodeficiency and immune diseases and cystic fibrosis, not taking drugs that weaken the immune system, the absence of pneumonia before the intervention according to the Modified clinical pulmonary infection score (MCPIS), at least 48 hours have passed since the patient was hospitalized. Exclusion criteria were return of consciousness and no need for MV before 48 hours connected to the device, transferring the patient to other departments before 48 hours from connecting to the device and the death of the patient before 48 hours connected to the device. Included all under ventilators patients, who hospitalized the ICUs of Golestan and Amiral Momenin Hospitals in Ahvaz city, Iran.
In order to start the research, after obtaining the necessary permits and receiving the ethics code (R.AJUMS.REC.1399.229) from the ethics committee and research vice of Ahvaz Jundishapur University of Medical Sciences, and explaining the research process to the authorities, according to the inclusion criteria, 92 samples from Amiral Momenin Hospital (closed suction group) and 92 samples from Golestan Hospital (open suction group) were selected.
In order to evaluate the first primary outcome, the incidence rate of VAP, the absence of pneumonia was confirmed in the samples using the MCPIS tool. Then to obtain informed consent of the the patients’ guardian, the necessary information, including the type of disease, the measures taken in the research, and the benefits and side effects of the measures, were explained to the guardian in a simple and understandable language by the researcher in such a way that, while preventing stress to the guardian, the necessary facts were given to the guardian. Necessary explanations and group trainings were given by the researcher about the correct way to perform open and closed suction according to the standard protocols and the purpose of the study to the ICUs nurses who were selected as available. The required equipment for open suction were open suction device and set, sterile gloves, gown and glasses, sterile bowl, physiological serum, y-shaped connecting tube, sterile gas, receiver; and for closed suction including closed suction device, physiological serum.
In the intervention group, the closed suction system was used, which was the routine method of Amiral Momenin Hospital. The closed suction set is manufactured by the Taiwanese Biotech company and has two numbers, 14 and 16, the length of both catheters is 54 cm, and the only difference is the diameter of the catheter, which is 4.67 mm in size 14 and 5.32 mm in size 16 catheter. According to the instructions of the manufacturer of this product, the duration of using this type of suction is 72 hours, which are disposable and cannot be sterilized or reused. Also, because the closed suction tube is covered with a thick layer of transparent plastic, the sterility of the suction tube is maintained, so there was no need for the nurse to wear sterile gloves. The closed suction system was used for 5 days, and due to the fact that early pneumonia occurs before the fifth day, the follow-up was done until the fifth day, and on the morning of the fifth day. In the closed system suction, suction was performed without disconnecting the patient from the ventilator. In this method, the head suction was placed at the connection point of the ventilator to the tracheal tube using a Y-shaped tee. If the suction of secretions was necessary, without interrupting the MV, the suction head was connected to the suction and entered the tracheal tube through a tee. After draining the secretions, the suction catheter was removed from the tracheal tube, but without contacting the outside environment, it was placed inside its own cover and remained connected to the tee.
In the control group, the open suction system, which was the routine method of Golestan Hospital, was performed using the green nelaton with number 14 and orange with number 16 manufactured by the Iranian Mehr Tab Company. First, open suctioning and preparation were explained to all the nurses involved in the department by the researcher in a group, so that before suctioning, the patient should be hyper oxygenated with 100% oxygen for two minutes., then following the sterile conditions, which includes opening the sterile set in the standard way, wearing a gown and glasses, spreading a sterile towel under the tracheal tube, connecting the sterile set to the suction device, turning on the suction device, wearing sterile gloves, placing the sterile probe in the dominant sterile hand and starting the suction gently and paid attention to the movements of the patient's chest and temporarily separated the patient from the ventilator, and then suctioning the tracheal tube with a maximum negative pressure of 120 mm Hg was performed 1–2 times and each time for 10 seconds. After that, the patient was connected to the ventilator and hyper oxygenated with 100% oxygen for two minutes.
It is necessary to explain that the suction in both methods was performed by the suction device located next to the patient's bed and connected to the central suction, with a negative pressure of less than 120 mmHg and following the principles of endotracheal tube suction, and the time interval between suctions, it was at least 90 minutes to prevent the side effects of suction.
A chest x-ray was performed one or more times according to the doctor's order in case of suspicion of pneumonia. All x-rays and, if any, infiltration were checked and diagnosed under the supervision of the attending physician. Medical tests were also taken once a day for 5 consecutive days and the results were followed up for 5 days, and since the incidence of early-onset pneumonia was considered in this study, it was not necessary to perform tests more than once a day. The measures taken in the research, including tests and chest x-ray, were part of the patient management protocols in the ICU, which were observed and recorded by the researcher during the shift, and no cost was imposed on the patients.
To assess the second primary outcome, the rate of hypoxia changes, arterial blood tests were routinely taken by involved nurses 30 minutes after the first suction in the morning and when the patient was calm. Initially, The 20 gauge syringe was fully heparinized, then returned the heparin into the ampoule so that 0.1 mm remains inside the syringe, then changed the 20 gauge needle to 22 gauge and drained the remaining heparin. Then wear gloves and determine the location of the artery and take a sample from the strong pulse after disinfecting the area with an angle of 30–45 degrees from the radial and 60 degrees from the brachial up to 3 ml syringe and after that, cover the area with a pad or gauze for 5–10 Hold tight for a minute until the bleeding stops. Ventilate the syringe and keep it in a container with ice and send it to the laboratory along with the patient profile form.
The estimation of the sample size based on the study of Mohammad pour et al. (18) and considering the first objective of the study, the values of 48.6%, P2 = 28%, P1 = 0.05 with a significance level of 0.05 and a power of 80%, the sample size was estimated to be 84 people in each group using the following formula. Considering the 10% attrition, the sample size was 92 people in each group.
Data collection
The data collection tool was a demographic information questionnaire (age, gender, history of smoking, disease diagnosis, underlying disease, and medication), a medical checklist based on MCPIS and pulse oximetry device. MCPIS was introduced in 1990 by Pugin et al. and in addition to the criteria mentioned above, it also had secretion culture. Pugin et al. considered a score above six of these criteria to indicate pneumonia. The sensitivity of this tool was 93%, the specificity was 100%, and a correlation of 0.8 was reported (19). The reliability of the Iranian version of this tool was done by Saberi et al. To determine the reliability, internal consistency method was used by calculating Cronbach's alpha and the internal correlation coefficient was 0.91 (4).
Medical checklist including taking a chest x-ray and the type of lung secretions diagnosed from X-ray by physician over 5 days, lowest and highest patient temperature during the day for 5 days of study, The patient's respiratory tests and indicators included daily blood cell count to record white blood cell count and daily arterial blood gas analysis to record arterial blood oxygen pressure and the ratio of arterial oxygen pressure to the oxygen percentage of the inspiratory air of the ventilator. Respiratory indices included arterial blood oxygen saturation based on pulse oximetry (every hour), arterial blood oxygen pressure (based on arterial blood gas analysis) and the ratio of arterial blood oxygen pressure to arterial blood oxygen percentage (Pao2/Fio2).
The pulse oximetry device that was used for the patients was the central pulse oximetry system of Saba for Golestan hospital and the pulse oximetry system of the central system model live w110 for Amiral momenin hospital. At the beginning of the study, in order to calibrate the pulse oximeter device, the pulse oximeter was connected to the two hands of the patient at the same time, and both devices were observed for 5 minutes, and the parameters were measured. They were the same in both devices. Therefore, the device under review was reliable, and of course, to ensure the accuracy of the device's operation, the reliability of the device was tested in the same way once every two weeks during sampling.