Discussion
Airway and breathing management skills are of paramount importance in the Emergency Department. This importance becomes even more significant during the resuscitation of the crashing trauma patient. Failure to efficiently manage the airway contributes to increased mortality and morbidity in these patients. Securing the airway in the setting of trauma, poses a considerable challenge in light of multiple other associated factors; like altered sensorium, shock, maxillofacial and spinal injuries or thoracic and neck injuries.
Rapid Sequence Intubation is the most widely used technique for emergency intubation of patients in the ED, with recent large registry data showing that it is used in 85% of all intubations in the emergency setting 1, 2.
RSI consists of three phases- Pre-oxygenation, Endotracheal tube placement and Placement confirmation. In the already compromised trauma patients, any delay in the latter two phases can lead to the worst outcomes. The efficacy and speed of intubation depends upon the skill of the clinician. Early confirmation of tube placement is crucial in order to prevent further compromise due to adverse events like oesophageal or right main stem bronchus intubation 3.
Various methods have been described for distinguishing between endotracheal and oesophageal placement of the tube, which include visual confirmation during laryngoscopy, expansion of the chest wall during ventilation, auscultatory method, capnography, and chest X‑ray.
The current recommended method for confirming correct placement of an endotracheal tube, as per ACLS guidelines [2015] is continuous waveform capnography, in addition to clinical assessment 4.
Capnography is the currently accepted gold standard method for confirmation of ET tube position but it has several limitations, especially in the emergency setting. As waveform capnography works on the principle of detection of carbon dioxide, this proves unreliable in the setting of shock which is a common presentation in many trauma patients. Also, there is a limited availability of ETCO2 monitors in most ED’s.
Recent studies have identified Point of Care Ultrasound as a potential method to confirm proper ETT placement 5, 6. POCUS is an easy, portable, non-invasive and inexpensive bedside imaging modality which has myriad applications in the field of Emergency Medicine. 7
The current study, a prospective randomized control trial, aimed at the utilisation of point-of-care ultrasound during RSI in trauma victims. It also compared the utility of POCUS versus clinical examination in detecting tube placement in these patients, though confirmation of placement in all was done by the currently accepted gold standard technique of waveform capnography. This helps the Emergency Physician in early identification of airway or breathing problems, such as hematomas, tracheal tears, pneumothorax and vascular injuries and to plan accordingly.
In our study, majority of the patients were males, which was similar to the other studies done by Chou et al, Mishra et al and Thomas VK et al6, 8, 9. Majority of our patients were in the 25-35 year age group and the most common mechanism of trauma was road traffic accident, which is in accordance with the WHO’s Injury and Violence Facts10 and also the findings of the study by Mishra et al 8. We found that the most common indication for RSI was airway protection, which correlated with the findings of previous studies 8, 9, 11.
Pre and post-intubation vital parameters of all patients of our study including Pulse Rate, Systolic Blood Pressure, Diastolic Blood Pressure and Saturation of Oxygen were found to be similar.
Mishra et al in a prospective randomized control trial found that during primary survey, without the aid of POCUS, there was a 3% incidence of clinical pneumothorax in the study population 8. This finding was comparable to our study which detected 4% of the study population.
In a prospective study by Kirkpatrick AW et al, using point of care sonography in a trauma centre, detected post-traumatic pneumothorax in 22% of the total population 12. Lichtenstein et al conducted a retrospective study and found that ultrasound was an effective bedside modality for diagnosis of occult pneumothorax, thereby reducing the need for computed tomography in a retrospective study 13. Nagarsheth et al conducted a prospective, single blinded study for identifying pneumothorax by ultrasonography as compared with CT and chest X-ray and found ultrasonography to have high sensitivity and specificity 14. During primary survey of the trauma populations with the aid of POCUS, Mishra et al found nearly 8% to have absent lung sliding which was suggestive of pneumothorax 8. This was comparable with the results found in our study. Additionally, we also detected the presence of neck hematoma in 1% of the population, which again correlated with the study findings of Mishra et al 8.
Wong et al conducted a prospective observational study in critically ill non-trauma patients, where they detected 4% to have an anticipated difficult airway 15. In our study, we found an anticipated difficult airway in 17% of the patients.
The mean time taken for the primary survey in the study conducted by Mishra et al was 20 seconds in the PA arm vs 18 seconds in the CE arm8. In our study, the mean time taken was 25 seconds vs 22 seconds in the PA and CE arm respectively. The difference was found to be statistically significant with a p value<0.001. Hence, usage of POCUS may prolong the time taken for primary survey, as compared to clinical examination alone.
Recent studies have demonstrated that the time needed to confirm endotracheal tube placement using POCUS ranged from 5 to 45 seconds16, 17, 18. Two studies compared the time taken using ultrasound vs capnography and found that ultrasound took shorter duration than waveform capnography 18, 19. Thomas VK et al underwent a prospective cohort study, concluded that ultrasonography method (8.27 ± 1.54 seconds) took significantly less time compared to clinical methods (20.72 ± 3.21 second) and ETCO2 detection (18.06s ± 2.58 seconds) for confirming tube placement (p-value <0.001) 9. Chou et al conducted a prospective, observational study and found that the time required for tracheal intubation confirmation using tracheal rapid ultrasound exam (T.R.U.E.) was 14.8±18.7 seconds 7. Mishra et al found that the mean time taken from the beginning of intubation to correct placement of the ET tube, and its confirmation by the presence of left lung sliding sign in the PA arm was 37.3 seconds (SD = 21.92). Similarly, the duration in the CE arm was 58 seconds (SD = 32.04)8. In our study, the mean time taken from the beginning of intubation till positive confirmation of tube placement was significantly lesser in the PA arm when compared with the CE arm (45.00 ± 7.83 seconds vs 91.36 ± 19.63 seconds, p<0.0001). From the above findings, it is evident that incorporation of POCUS into RSI of trauma patients leads to earlier confirmation of tube placement and this is a crucial advantage in the Emergency setting where time is of essence.
Mishra et al, in their study, found that 4% of the total intubations were oesophageal 8. In two separate studies conducted by Thomas VK et al9 and Reddy et al 20, 5 % of the total numbers were detected to be oesophageal intubations. A study conducted by Chou et al found 15% oesophageal intubations in the total population 7. In our study, we found that 5% of all the intubations were oesophageal.
The mean time taken to detect oesophageal intubation was 22 ± 2s in the PA arm of our study, as compared to 114 ± 5.65s in the CE arm with a statistically significant difference between the two (p< 0.0001) . Mishra et al found that the mean time taken to identify oesophageal intubation by using POCUS was 18.25 s vs 177.5 s taken to detect the same by clinical examination 8. Muslu et al conducted a prospective randomized control trial and found that POCUS could detect ET tube position in the trachea or the oesophagus in an average of 3 seconds 21. Several studies conducted during intubation found that POCUS had high sensitivity for identifying oesophageal intubations 21, 5, 16, 17, 22, 23, 24, 25, 26. From the above data, we can infer that POCUS can be used as a tool for rapid identification of untoward airway complications in RSI like oesophageal intubations.
Following the detection of oesophageal intubation in our study, the mean time taken for re-intubation was 26.67 ± 3.05 seconds in the PA arm and 55 ± 7.07 seconds in the CE arm and the difference between the two was found to be statistically significant with a p value < 0.007. Mishra et al found that in their study, the average time taken for reintubation was 23.12 seconds, when endotracheal tube placement was confirmed by the left lung sliding sign 8. When correct tube placement after reintubation was confirmed by EtCO2 value, the mean reintubation time became 39.5 seconds 8. As previous studies have already demonstrated the utility of POCUS in leading to faster confirmation of tube placement, it therefore also helps to hasten the process of reintubation and prevent further decompensation.