Soft Drink Straw as an Alternative Device of Creating Positive Expiratory Pressure (PEP) in Thoracic Surgery Patients

INTRODUCTION

The use of positive expiratory pressure devices is considered beneficial in patients who have undergone abdominal and thoracic surgery with an impact on blood gas measurement values, the hospitalization length, the use of antibiotics and the pathology of the chest. Of course, there are researchers who doubt the effectiveness of the method, mainly due to the fact that it does not possibly reduce the risk of atelectasis, especially in patients who undergone cardiac surgery. However, the method is very popular in physiotherapy, and the use of alternative devices that create positive expiratory pressure, such as water bottles or gloves, is suggested, especially in cases when the access to the classic devices is not easy, mainly during the periods of crisis.

Coughing is a process that ensures the cleaning and protection of the airways. The outcome of the thoracic surgery may often depend on the quality of the patient's cough postoperatively which may put the patient at risk that could last for up to eight weeks. The effectiveness of the cough can be assessed by measuring the peak cough flow using a peak flow meter, method that many researchers in Europe and America prefer. Cough with a maximum expiratory flow over 160 L/min could ensure a safe extubation or decannulation of severely ill and postoperative patients. Therefore, if there was a way leading to cough enhancement, this could be a lifeline to the recovery of these type of patients.

PURPOSE

The present study was performed to test the suitability and effect of a soft drink straw as an alternative positive expiratory pressure device in patients undergone thoracic surgery and includes two sub-exploratory areas.

In the first one, it was investigated the most appropriate command of exhalation into a specific internal diameter straw, whereas on the other hand, it was examined the improvement of patient's overview by using the particular alternative device.

RESEARCH HYPOTHESIS

Is there any possibility of a simple soft drink straw being an alternative PEP device which could improve the cough flow of patients who undergone thoracic surgery?

METHODOLOGY

The research was approved by "ATTIKON" University General Hospital (with reference number 725/25/11/2019) and by the University of Thessaly (with reference number 101SE2/16-01-2020).

The study was performed at the Cardiac Surgery Clinic of "ATTIKON" University General Hospital and participated all the adult thoracic surgical patients, with no limit of age, from 12-02-2020 to 08-03-2020 Patients beforehand, are informed with the purpose of the study and necessarily sign the Patient Consensus Form for their participation in the study.

Sample:

The sample of present study included all adult patients that undergone thoracic surgery, with no limit of age, with a mesosternal or lateral incision, who considered hemodynamically stable, were supplied with an O2 mixture of below 50%, full-conscious, with systolic pressure below 150 cmH20. The records were carried out on the 2nd and 3rd postoperative day.

Patients with history of chronic respiratory disease, with severe symptoms, tendency to vomit, cardiac arrhythmia due to atrial fibrillation postoperatively, and patients with angina were excluded from the study. The records were carried out in the morning or at noon and were automatically stopped if patient had any difficulty, decrease in saturation ≤90, feeling of dizziness, fainting and palpitations. The number of volunteers excluded from the study was n = 4 (2 people due to dizziness during the sitting position, 1 person with a tendency to vomit before the beginning of the process and 1 person due to re-intubation before the beginning of the process).

Procedure:

All patients were beforehand informed about the purpose of the study and signed the Patient Consensus Form in order to participate the study. Data, such as age, height and weight, type of surgery and concomitant pathologies, if any, were collected. Patients' medical records were examined to verify the collected information and find any indication that could have led to their exclusion from the study. Records and measurements were begun only after consultation with patient's doctor.

Each participant was placed in a sitting position, with his popliteal region of the knees near the edge of the bed and stayed in this position for at least 2 minutes in order to be checked that he won't develop any symptom such as discoloration of the face's skin, dizziness or fainting. In case of appearance of any of the above symptoms, patient was placed back in a supine position and the procedure stopped. Patients who felt a very light dizziness detected by overview or oral evaluation, remained seated until the symptom passes and then records and measurements were started. If the symptom continued, the procedure was stopped and patient returned to the supine position.

In the first phase of the study, all volunteers' saturation and heart rate was recorded using oximeter or monitor's indications, whereas the recording of respiratory rate followed by placing one researcher's hands on the subject's epigastrium. Both systolic and diastolic blood pressure were recorded with an analog pressure gauge, as well dyspnea (calibrated using the borg scale) and thoracotomy pain, which was quantified using the numerical pain scale (Numeric Rating Scale - oral application).

The maximum expiratory flow of air during coughing was estimated with a Peak Flow Meter (PFM) device. Participants applied their lips to a disposable mouthpiece, which was connected to the PFM and followed the command "please cough hard inside the device". The value recorded through the PFM device, which was the airflow during coughing, corresponded to the Cough Peak Expiratory Flow. Patients' surgical trauma was supported by holding a pillow on the incision during cough attempts, whereas there was no visual contact with PFM.

Intervention:

The first part of the study was to investigate the most appropriate command for exhalation through a straw of a certain inner diameter (5mm) and carried out by using a device consisted of a drinking straw, a disposable mouthpiece and a manometer to quantify the developed pressures during the exhalation attempts. The sample of this part included all the volunteers. Patients did not have visual contact with the manometer. The effectiveness of each command (Command A: "please blow continuously so that you feel low resistance during exhalation" and Command B: "please blow continuously so that you feel moderate resistance during exhalation") was estimated by comparing the average of the developing pressures during exhalation attempts arose by the corresponding command with the therapeutic range of pressure (10-20 cmH2O). This part of the study was a cross-sectional transition and every volunteer performed 3 attempts for each command. The outputs of the above attempts were recorded but only the ones of the 3rd attempt were used to the study.

The second part of the study was conducted to evaluate the benefits arising from the use of a drinking straw as an alternative PEP device. A number of n = 8 volunteers (intervention group) was selected from the total sample, using the closed envelope method. The remaining volunteers (n = 5) consisted the control group. Taking into account the results of the first part of the study, intervention group was requested to exhale as indicated by the "right" command, performing 3 sets of 10 repetitions, included short breaks between sets.

After the intervention phase, all patients were re-examined to measure the Cough Peak Expiratory Flow, dyspnea, pain, saturation, heart and respiratory rate, systolic and diastolic blood pressure.