INTRODUCTION

One of the early signs of acute illness is the deterioration of respiratory function in patients. The respiratory disorder is one of the major causes of critical illness and is considered one of the main reasons for admission to intensive care units [1]. The impairment of the respiratory system and the inability of the patient to perform spontaneous respiration is the most important challenge in the intensive care unit. Therefore, the use of mechanical ventilation and the application of an intubation tube is an integral part of these sections [2]. Since patients with an artificial airway, such as the tracheal tube and intracranial hemorrhage, are unable to cough and remove pulmonary secretions, the accumulation of secretions in patients with a critical condition that has an endotracheal tube and a weak cough, causes airway obstruction in the gas exchange [3]. Consequently, it will result in a decrease in arterial oxygen pressure, acidosis, cyanosis, drowsiness, disturbance of consciousness, and cardiac dysrhythmia [4]. Therefore, to clean the airway and to maintain the airway open, tracheal suction is used in abundance in special sectors, especially the ICU [5, 6]. The tracheal suction is one of the most important and necessary interventions in nursing, which removes the secretions from the respiratory tract and prevents the accumulation of secretions, and increased respiratory function, atelectasis, and respiratory infection [7]. However, in addition to the benefits and necessities of doing it, suctioning is accompanied by some complications such as airway damage, bronchial spasm, hypoxemia, cardiac rhythm disorders, ventilator-dependent pancreas, emphysema, pneumothorax, rupture of chip and mild to severe bleeding, increased intracranial pressure and cardiac arrest and death [2, 3, 8]. The main goal of suctioning the inside of the trachea is to remove secretions from the airways. If the secretions of a patient who is not able to cough due to the presence of the tube are not removed, then air sacs are created. Of course, doing this is not divorced from risk and complication, the accumulation of air in the adjacent layer, pneumonia, bacteremia, necrosis of the chest, and changes in blood flow are all the complications that threaten patients requiring suction. As the suction tube passes into the trachea, the movement of mucus covering membranes of the trachea is reduced and destroyed; following the destruction of the tinnitus and trachea stimulation, the mucus production is markedly increased, and as a result, the need for suction is increased [9]. The most common complication of airway suction is hypoxemia, which can cause changes in heart rate, heart rhythm disorders, and imbalance in hemodynamics by stimulating the adrenergic system which is a compensatory mechanism in response to the reduction in the amount of oxygen in the blood [4]. On the other hand, suction may result in loss of arterial oxygen saturation, followed by side effects such as heart rate abnormalities, cardiovascular collapse, and even sudden death [7]. Also, hypoxemia can cause cell death, and in milder cases, it can weaken brain activity, coma, and decrease muscle function [10]. Therefore, taking into account the effects of suction, especially the complication of hypoxemia and its effects on various organs of the body, the prevention of this complication is very important. Therefore, researchers have proposed a method called hyperoxygenation that can significantly reduce the hypoxemia associated with endotracheal suctioning [2, 6, 11, 12]. John Jordan and colleagues (2012) state that the development of cardiac arrhythmias during endotracheal suctioning is due to hypoxemia. By performing hyperoxygenation before and after the suctioning process, hypoxemia, and as a result, cardiac arrhythmia can be prevented [13]. Although various studies have shown that hyperoxygenation has a positive effect on the amount of oxygen saturation during suction, the results are different in these studies. For example, in the study of Oh and Seo that was done to clarify the effect of interventions that have a preventive role in the development of hypoxemia pao2, sao2, pao2 / fio2, svo2 were investigated as measurement indices of hypoxemia. The results showed that the most common method for the prevention of hypoxemia is hyperoxygenation where oxygen is 100% and the volume is equal to one hundred and fifty percent of the vital volume during three to six respiration [14]. On the other hand, hyperfluidation with a volume of 150% of flowing air volume can increase intracranial pressure in patients with a head injury.

A study was carried out by Orand et al. to provide a guide to improve the clinical performance of the members of the health care team during the suctioning of patients under mechanical ventilation. To collect information, articles from MEDLINE, CINAHL, EMBASE, and resources from the Cochrane Library from 1998 to 2007 were used. The results of studies showed that hyperoxygenation during tracheal suctioning in patients undergoing mechanical ventilation has been recommended since 2001 on the majority of resources as an intervention to maintain blood oxygen levels and a preventive method for the loss of arterial oxygen saturation in patients with trauma and patients with chronic obstructive pulmonary and heart diseases [15]. This study also referred to the necessity of conducting studies with a larger sample size to evaluate the suction indication, the duration of hyperoxygenation, the clearance of the airway with minimal complications, and the examination of suction in non-intubated patients (due to limited information).

Regarding the limitations of previous studies on the duration of hyperoxygenation concerning the effects of duration of hyperoxygenation on hemodynamic parameters, the researchers aimed to compare the effect of hyperoxygenation 1 minute and 2 minutes before the tracheal suctioning on the number heart rate and arterial oxygen saturation in ICU patients. The general aim of this study was to determine the effect of hyperoxygenation duration before tracheal suctioning on heart rate and arterial oxygen saturation in patients admitted to intensive care units.

MATERIALS AND METHODS

This study was a randomized controlled trial. The statistical population of this study included patients admitted to the ICUs of Peymanieh Hospital in Jahrom, who were admitted to the hospital during the research. Sampling was done among patients who met inclusion criteria and after giving explanations about the research and obtaining informed consent from patients' guardians they entered the study. The conditions for entering the study included: patients with trauma admitted to intensive care units with tracheal intubation under mechanical ventilation and had been admitted at least 48 hours earlier, aged between 18 and 65 years, no lung injury according to radiologic studies and expert opinion, stable hemodynamic status (SBP> 100mmHg, output = 30cc / hr, HR = 60-100) and the lack of cardiac arrhythmias, the absence of a history of chronic pulmonary disease and acute respiratory infections, the absence of symptoms indicating an increase in ICP and the need for three episodes to clear the airway in each episode of suctioning the trachea. Patients with hemodynamic imbalance during the intervention and median arterial blood pressure of less than 60mmhg were excluded. Patients were randomly assigned to one of the two groups of one-minute and two-minute hyperoxygenation. Then, tracheal suctioning was done by the researcher according to the patient's needs. The procedure of tracheal suctioning was done on each patient once. The researcher prescribed 100% oxygen to the patient before tracheal suctioning, which was 1 minute for one group and 2 minutes for the other group. The suction process was carried out at a negative pressure of a maximum of 120mmhg [16]. The number of entrances of the suction tube into the trachea and the application of suction for each suction period was 3 times, which took approximately 15 seconds. Between episodes 1, 2, and 3, the patient was reconnected to the ventilator for forty-five seconds and received oxygen at 100%. After completing the third episode of suction, 100% oxygen was given to patients in both groups for 1 minute. If a patient needed fewer or more episodes of catheter insertion and suctioning during any suction period, that suction period was removed and re-measured in the next period. The data gathering tool in this study included a form that included information such as hospitalization code, age, sex, hospitalization date, and parameters under study (heart rate and arterial oxygen saturation). It should be noted that the parameters were recorded in the data recording tables at five minutes and thirty seconds before the start of suction, during suction, immediately after the completion of suction, five minutes after the completion of suction, and twenty minutes after the completion of suction. To monitor the hemodynamic variables, the S1800-ER monitoring device belonged to Pouyandegan Rahe Saadat company. Electrodes on the patient's chest were connected to the patient to monitor heart rate and a finger probe was connected to monitor the amount of arterial oxygen saturation. The reliability of the monitoring device was evaluated by the manufacturer's instructions.

After collecting data and checking the necessary data and encoding them, the data were entered into the SPSS version 16 software. Initially, the comparison of the two groups was done in terms of equalizing the underlying and confusing variables and the data compliance with a normal distribution. Data were analyzed by descriptive statistics of independent t-test for quantitative variables and the Chi-square test for qualitative variables. Repeated Measure ANOVA and post-test were used to compare changes in each group. The level of 0.05 was considered significant for the results.

RESULTS AND DISCUSSION

The findings of the study on 42 patients under a ventilator showed that the mean age of the patients under study was 41 years with a dispersion of 33-50 years. Based on the results of ANOVA, there was no significant difference between the two intervention groups in terms of quantitative variables (P = 0.923). The majority of patients, 76.2%, in the two interventional groups were male. In this study, the comparison of the mean oxygen saturation in the two groups was compared (Table 1).

The result of the ANOVA test showed a significant difference in different stages of suction in the two groups. The results of the LSD post-test indicated that: there was no significant difference between the two groups in the mean O2 sat at 5 minutes before suctioning. There was no significant difference between the mean O2 sat in any of the suctioning stages in the two groups of pre-oxygenation for one minute and two minutes.

Also, in this study, the mean heart rate changes were compared in the two groups of patients at different suction times (Table 2).