Abstract
Several patients of cardiac arrest may be found in a state of agonal gasps that are of insufficient tidal volume and are not considered as a sign of life. However, this volume is sufficient enough to cause appreciable inflation and deflation of the reservoir bag of Umesh's intubation detector (UID) as evidenced in all 12 victims of cardiac arrest with gasping efforts in this study. Therefore, we conclude that the agonal gasps during cardiac arrest can reliably be used to confirm tracheal intubation using the UID device.
Keywords
cardiopulmonary resuscitation; intubation, intratracheal; respiratory insufficiency: agonal respiration; umesh's intubation detector;
1. Introduction
Waveform capnography has been the gold standard for confirmation of tracheal intubation and for detection of esophageal intubation.1, 2 However, a capnograph is not readily available at all locations, especially in emergency departments and in out-of-the-hospital scenarios.3 Umesh's intubation detector (UID) is one device that may be a useful alternative to several other devices available for confirmation of tracheal intubation in situations where waveform capnography is unavailable. The UID device (Fig. 1) functions on the physiological understanding that the chest compressions provided during cardiopulmonary resuscitation (CPR) result in compression of both the heart and the lungs, and hence, a variable quantity of gas from the lungs will be forced out of the tracheobronchial tree with each chest compression. Therefore, when the UID is connected to the tracheal tube, the reservoir bag of the UID should inflate and deflate with each chest compression if the tube is in the trachea. By contrast, there should not be any inflation of the reservoir bag of the UID if the tube is in the esophagus.4, 5, 6
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It is well known that several patients of cardiac arrest may be found in a state of agonal gasps. These gasping efforts of the victims are of insufficient tidal volume and are not considered as a sign of life. Hence, rescuers are advised to initiate CPR in victims that are found in an unresponsive state without any palpable pulse even in the presence of gasping efforts.7 However, the gas flows that occur during gasping efforts may be sufficient enough to cause appreciable inflation and deflation of the reservoir bag of UID. To test this, we evaluated the utility of UID in detecting tracheal intubation in victims of cardiac arrest who had gasping efforts.
2. Study details
The study protocol strictly adhered to the Declaration of Helsinki. Written informed consent was obtained from the nearest relative of the patients involved in the study. Upon receiving the code-blue (cardiac arrest) call within the hospital, the code-blue team comprising an anesthesiologist, a respiratory therapist, and a nurse were immediately dispatched to the place of cardiac arrest. On confirming cardiac arrest (unresponsiveness and absence of carotid pulse), the team initiated CPR with chest compressions. While the initial set of chest compressions were going on, the anesthesiologist secured tracheal intubation by direct laryngoscopy. In the absence of waveform capnography, tracheal intubation was confirmed by clinical measures. In addition to this, in patients who had gasping efforts at intubation, the UID was connected immediately following tracheal intubation and observed for inflation of the reservoir bag on gasping. While the chest compressions were continued during and after tracheal intubation, they were interrupted for a brief period of 2–3 seconds when a gasping effort was observed. The response of UID was considered positive for tracheal intubation if the reservoir bag was observed to be deflating initially (gasping inspiratory effort of the victim) followed immediately by inflation (passive expiration). This way, the response of UID to gasping efforts could be distinguished from the effects of residual pressure of CPR.
If the patient did not show any gasping effort in the first 10 seconds after intubation, the UID was disconnected and a manual resuscitation bag was connected and the patients received positive pressure ventilation at approximately 8 breaths/minute without interrupting the chest compressions. The period of study was 6 months between January 2012 and June 2012. All the cardiac arrest calls attended by the team of investigators in this period were considered for the study.
There were a total of 68 in-hospital code-blue calls attended by the investigators in the period between January 2012 and June 2012. Of these, 63 were found to be in cardiac arrest when the team reached the site of call. Of these 63, there were a total of 12 victims who had gasping efforts in the first 10 seconds following tracheal intubation. The demographic data are given in Table 1. In 11 of these 12 victims, the tracheal intubation was confirmed by visual inspection of the tube passing between the vocal cords and five-point auscultation. The inflation and deflation of the UID during chest compressions added further confirmation to clinical measures. In all these patients, a gasping effort was observed within 10 seconds of tracheal intubation and was promptly detected to be positive for tracheal intubation using the UID. However, in the other victim with agonal gasps who had sustained whole-body burns, the anesthesiologist could only visualize the epiglottis while performing tracheal intubation and hence was not sure of correct placement of the tube. Clinical confirmation was difficult and unreliable due to burns involving the chest and abdomen. On connecting the UID, there was no visible or appreciable inflation of the reservoir bag of UID with either the agonal gasps or chest compressions. Suspecting a possible esophageal intubation, the tube was removed and a second intubation attempt was carried out, which was aided by Frova intubation introducer. This intubation attempt was partly confirmed by the serial clicks and distal holdup signs as the Frova intubation introducer was passed into the trachea. On connecting the UID to the tracheal tube, inflation of the reservoir bag of the UID with both gasping attempt of the victim and chest compressions helped further confirm tracheal intubation.
3. Discussion
Although most operating rooms and intensive care units are equipped with waveform capnography equipment, which is the gold standard for confirming tracheal intubation, several other areas may not possess waveform capnography.3 Several alternative techniques and devices have been used for confirming tracheal intubation in such instances. Unfortunately, all of them seem to have a number of limitations including the UID. Therefore, this study attempted to find whether UID can reliably confirm tracheal intubation in those patients with agonal gasps. As the study results show, agonal gasps can be reliably used to confirm tracheal intubation using the UID. Although it is logical to expect spontaneous respiratory efforts to cause the reservoir bag of UID to inflate, the fact that the agonal gasps during cardiac arrest can help in the confirmation of tracheal intubation appears exciting.
In one of patients where two attempts were needed for tracheal intubation, the presence of serial clicks and distal holdup signs while using the Frova intubation introducer helped confirm tracheal placement of the introducer. Further confirmation of correct tracheal placement was with the inflation and deflation of the UID with both agonal gasps and chest compressions. The fact that the first attempted intubation did not generate bag movements in the UID with gasps or chest compressions and the second intubation revealed clear bag movements clearly demonstrates that the endotracheal tube was in the esophagus on the first occasion.
In the absence of waveform capnography, it is essential to have multiple methods for confirmation of tracheal intubation or for detection of esophageal intubation to minimize false interpretations.1 Therefore, use of devices such as UID in addition to clinical measures for confirmation of tracheal intubation will be helpful. Furthermore, additional confirmation provided by gasping efforts during the use of UID in addition to confirmation during chest compressions will enhance the chances of correct and rapid recognition of tracheal intubation.
Based on the results of this simple study, we conclude that the agonal gasps can reliably be used to rapidly confirm tracheal intubation using the UID device.