Endotracheal tube cuff pressure – how fast paramedics can learn the optimal ination? comparison of different methods

Tracheal intubation is the optimal method for opening up the airways. Performed correctly, it prevents stomach contents from entering the respiratory tract, and allows asynchronous CPR to be conducted during sudden cardiac arrest. An important element of correct intubation is proper ination of the endotracheal tube cuff. Research has shown that when medical personnel use the palpation technique, the cuff is usually inated incorrectly. This can result in numerous health complications for the patient. This research was conducted in 2020 on a group of paramedics participating in the 15th International Winter Championship of Medical Rescuers in Bielsko-Biała. The aim of the research was to assess two methods of inating the endotracheal tube cuff. Method A involved inating the cuff using a syringe and assessing the pressure in the control cuff using the palpation technique. Method B involved inating the cuff using a manometer. During the ination, both the cuff ination pressure and the time required to complete the procedure were recorded. Analysis was also conducted on whether completion of certied ALS and ACLS training had any inuence on the effectiveness of the ination procedure. a simulation during simulated


Abstract Background
Tracheal intubation is the optimal method for opening up the airways. Performed correctly, it prevents stomach contents from entering the respiratory tract, and allows asynchronous CPR to be conducted during sudden cardiac arrest. An important element of correct intubation is proper in ation of the endotracheal tube cuff. Research has shown that when medical personnel use the palpation technique, the cuff is usually in ated incorrectly. This can result in numerous health complications for the patient.

Methods
This research was conducted in 2020 on a group of paramedics participating in the 15th International Winter Championship of Medical Rescuers in Bielsko-Biała. The aim of the research was to assess two methods of in ating the endotracheal tube cuff. Method A involved in ating the cuff using a syringe and assessing the pressure in the control cuff using the palpation technique. Method B involved in ating the cuff using a manometer. During the in ation, both the cuff in ation pressure and the time required to complete the procedure were recorded. Analysis was also conducted on whether completion of certi ed ALS and ACLS training had any in uence on the effectiveness of the in ation procedure.

Results
The research showed that paramedics using method B signi cantly more often in ated the endotracheal tube cuff to the correct pressure than those using method A. However, when method B was used, the procedure took longer to conduct. The study also showed that completion of certi ed ALS or ACLS training did not have a signi cant in uence on proper in ation of the cuff. Those who had completed certi ed training courses took signi cantly longer to in ate the endotracheal tube cuff when using method A.

Conclusions
In ation of the endotracheal tube cuff by use of a syringe, followed by the palpation technique for assessing the in ation of the cuff balloon is ineffective. Paramedic teams should be equipped with manometers to be used for in ating the endotracheal tube cuff.

Background
The endotracheal intubation procedure remains the most effective method of opening the airways during pre-hospital treatment. Proper insertion of the endotracheal tube prevents stomach contents from entering the respiratory tract and allows asynchronous cardiac resuscitation to be conducted, which minimizes the breaks between chest compressions, thus improving the quality of the resuscitation procedure [1].
An important factor in proper use of endotracheal intubation is correct in ation of the endotracheal tube cuff. The pressure required for correct in ation of the cuff should be in the range of 20 to 30 cm H2O. Assessment of the correct pressure should be precise and should be carried out using a manometer to indicate the cuff seal in ation pressure. Research in other countries has shown that assessment of cuff in ation using the palpation technique is relatively ineffective and rarely results in correct cuff in ation. Experienced paramedic specialists using the palpation technique to assess the amount of air in the cuff during intensive care conduct the procedure correctly in less than 30% of cases [2][3][4][5]. It has been proven that during palpation assessment, the cuff seal is overin ated, even to as high as 100 cm H2O [4]. Application of incorrect pressure in the endotracheal tube cuff seal can be extremely worrying as it may cause numerous complications [6][7][8][9][10][11]. In pre-hospital paramedic treatment, intubation is often used as the chosen method for clearing the airways. Unfortunately, attention is rarely paid to the correct cuff seal, and instruments for ensuring the seal during the procedure are seldom used. During paramedic treatment, in most cases a syringe is used and the amount of air is assessed using the palpation technique [12]. In this paper, we try to answer the question of what the differences are in the quality of endotracheal tube cuff in ation and the time required for the procedure, depending on whether a syringe or a device for in ating the cuff are used. The aim of the study is to determine the effect of using a device for in ating the endotracheal tube cuff in comparison to the use of a syringe, in terms of the cuff in ation volume and the time required for the procedure. We will also assess the in uence of completed certi ed Advanced Life Support (ALS) and Advanced Cardiovascular Life Support (ACLS) training courses on the achieved in ation volume and the time needed to in ate the cuff.

Methods
The research was conducted on the 30th January 2020 during a simulated rescue at the 15th International Winter Championship of Medical Rescuers in Bielsko-Biała, Poland. The research involved 108 paramedics working in ambulance response teams. The persons taking part in the research were from 32 ambulance stations from across Poland. Demographic data on the study participants is presented in Table 1 below. All study participants gave informed consent for the study to be carried out.  The study used a simulation technique and was conducted during a simulated rescue in order to maximize the similarity of the procedure to that used in real-life situations. The research was preceded by participants completing a short questionnaire with demographic data and the methods used by the participants for sealing the endotracheal tube cuff in clinical treatment. The procedure was carried out using a SIM Man ALS (Laredal) mannikin, serial number SN.23548170915, an endotracheal ID -7.5 tube, and a 20 ml syringe and manometer for sealing the VBM (Germany) endotracheal tube cuff. Measurements were also taken using a validated stopwatch by accredited research staff (no. AB1701. Polish Accreditation Center) from the paramedic laboratory at the University in Bielsko-Biała.
The mannikin was correctly intubated by a laboratory technician overseeing the study using an ID 7.5 endotracheal tube and a Mackintosh laryngoscope to a depth of 21 cm, measured from the left corner of the mouth. Every procedure was conducted using a brand-new endotracheal tube, which was inserted into the mannikin's trachea immediately before the cuff was in ated. The study comprised two procedure methods conducted one after the other.
Method A -involved sealing the endotracheal tube cuff using a 20 ml syringe. The time was measured from the moment the syringe was picked up to the moment the cuff in ation procedure was completed and the syringe placed beside the mannikin. Immediately after the procedure was completed, the pressure in the cuff seal was measured using a clock manometer.
Method B -involved sealing the endotracheal tube cuff using a VBM (Germany) device for in ating the endotracheal tube cuff. The time was measured from the moment the device was picked up to the moment the cuff in ation procedure was completed and the device placed beside the mannikin. Immediately after the procedure was completed, the pressure in the cuff seal was measured.
Analysis was also conducted of the effect of completed certi ed Advanced Life Support (ALS) or ACLS training courses on the quality of endotracheal tube cuff seal in ation.
All data was entered into a specially prepared Excel 2019 spreadsheet and subjected to statistical analysis.

Statistical Analysis
The assumed level of signi cance adopted was p = 0.05. Variables expressed at the ordinal or nominal level were analyzed using tests based on chi-square distribution.

Results
Analysis of the results obtained during the study should be complemented by key information contained in the questionnaires completed before the procedure was carried out. All the study participants indicated that the method they always used in conducting advanced paramedic treatment was that of in ating the endotracheal tube cuff by syringe. The main determinant they indicated for this choice of method was the time required for carrying out the procedure. None of the study participants gave in ated cuff volume as a condition that determined correct completion of the procedure. The pressure in cuffs in ated using Method A was signi cantly higher statistically than in cuffs in ated using Method B p < 0.05. In ation of endotracheal tube cuffs using Method A signi cantly less often statistically resulted in achievement of the required pressure (20 cm H2O -30 cm H2O) than during use of Method B. The time required to in ated the endotracheal tube cuff using Method B was signi cantly longer statistically than the time required using Method A p < 0.05. Completion of certi ed ALS and ACLS training courses did not have a statistically signi cant in uence on correct in ation of the endotracheal tube cuff relative to the method applied p>0.05. Participants who had completed certi ed ALS and ACLS training courses took signi cantly longer to in ate the endotracheal tube cuff using method A than participants who had not completed a training course. Among the participants in the study group (n = 74) who had completed certi ed ALS or ACLS training, 6.76% achieved a result of lower than 20 cm H2O, 8.11% achieved a result around the norm, while 85.13% achieved a result that exceeded a volume of 30 cm H2O. Among the study group participants (n = 34) who had not completed certi ed training, all achieved a result that exceeded a volume of 30 cm H2O. Completion of certi ed training does not therefore have a statistically signi cant in uence on achieving the correct in ation volume of the endotracheal tube cuff p = 0.059.

Discussion
In ation of the endotracheal tube cuff can be done using a syringe or by employing a manometer [12][13][14]. The authors of this study analyzed numerous publications that assessed the effectiveness of using a manometer during in ation of the endotracheal tube cuff. In none of these papers was there detailed information on the availability of this type of device among paramedic teams. The questionnaire used in our study showed that during their work in emergency medical teams, none of the study participants uses a manometer to in ate the endotracheal tube cuff. This is explained by the necessity to save time when working in two-person teams.
In ation of the endotracheal tube cuff to the correct pressure is one of the elements in properly conducted intubation. Carrying out the procedure correctly is di cult when it is done using a syringe [2][3][4][5].
Numerous research studies, both in clinical and in simulated conditions, have shown use of a syringe almost always results in excessive in ation of the cuff [4,5,13,14]. Over-in ation of the endotracheal tube cuff leads to patient complications in the area of the trachea, resulting in ischemia, infection or narrowing of the windpipe [15]. In their research conducted on human corpses, Sudhoff et al. demonstrated that excessive in ation of the endotracheal tube cuff can cause rupture of the trachea [16]. Our research has shown that when paramedics used a manometer, they correctly in ated the endotracheal tube cuff on every occasion, which demonstrates a statistically signi cant difference between this method and that involving use of a syringe. When a syringe was used, accompanied by assessment of in ation using the palpation method, over in ation occurred in 89% of cases. In other researches into proper endotracheal tube cuff in ation, authors indicate that too low pressure in the cuff seal can cause complications such as tube displacement or inhalation of stomach contents into the airways [9][10][11]. Our research showed that insu cient cuff in ation occurred in 4.63% of cases, and took place only when a syringe was used. Training certi ed by the AHA and ERC in advanced resuscitation techniques focus on teaching practical skills that can be later used during clinical treatment. This training includes workshops on correctly ensuring and maintaining unobstructed airways [17][18][19][20]. Many studies that include an assessment of the correct procedure for maintaining unblocked airways point to the need for improvement in the skills required for proper in ation of the endotracheal tube cuff [4,5,12,13]. Our research has proved that participation in certi ed ALS and ACLS training courses does not have a signi cant in uence on correct in ation of the endotracheal tube cuff, irrespective of which method is used. The research demonstrated that paramedics with an ALS or ACLS course completion certi cate took a statistically signi cant longer time to in ate the cuff by syringe than those who had not completed a training course. This may indicate that in contrast to medical staff who have not completed a training course, paramedics who have completed such a course are more aware of the importance and necessity of correctly in ating the cuff, although unfortunately this is not re ected in achievement of the proper cuff pressure.

Conclusions
Emergency medical teams should be equipped with devices for in ating the endotracheal tube cuff. The palpation method is ineffective in assessing the proper in ation of the endotracheal tube cuff. More emphasis should be placed on proper in ation of the endotracheal tube cuff during workshops on maintaining unobstructed airways conducted during certi ed ALS and ACLS training courses.