ProPublica published research done by Dr. Nick Asselin on cardiac arrests in Rhode Island and found esophageal intubation by EMS providers in 12 cases. All of the patients died. This story brings the attention back to skills needed to correctly intubate the patient in setting of stress of ongoing CPR.
Rhode Island is the only state in New England, and among a minority nationally, that allows non-paramedics to intubate patients. Dr Asselin and his research assistant stumbled upon the problems with patients’ breathing tubes in July 2018, while studying the effects of a new state protocol for cardiac arrest patients. They were studying the ” 30 minutes rule” of CPR at home, prior to bringing the patient to hospital and its impact. They studied 800 patients who had cardiac arrest at home and brought to emergency room. However, in 4% of the patients, the endotracheal tube was found to be in wrong pipe by the emergency room physicians. All of these patient died.
SEVERAL PROBLEMS IN ROW
The Swiss cheese model of accident causation tells us that in order to have an harmful impact, a series of mistakes had to be made. In this case, several problems happened in a sequence, resulting in death of above patients. First, was esophageal intubation, which can happen even with a seasoned operator. However, the 2nd mistake after the 1st is the not that common( failure to detect esophageal intubation). Furthermore, they failed to continuously monitor for mistakes.
GUIDELINES FOR AIRWAY MANAGEMENT IN OUT OF HOSPITAL CARDIAC ARREST
Current ACLS guidelines, which were updated in 2019, recommend either BMV or advanced airway can be considered during the CPR for the cardiac arrest. However, emphasis is on advanced airway by the trained individual. In another trial published in 2018, laryngeal tube insertion was considered superior to endotracheal intubation in out of hospital cardiac arrest. For most EMS personnel, out of hospital cardiac arrest is a rare occurrence, limiting their experience in endotracheal intubation. Time pressure and lack of support personnel also makes this process very difficult. Airway management in the emergency setting is often performed in uncontrolled circumstances, in combative or intoxicated patients, or in tight spaces with decreased visibility and often requires patient and head movement. Transportation to or within a medical facility also predisposes to malposition or displacement of ETTs. Endotracheal intubation is a skill that needs practice to acquire and maintain.
DETECTING PROPER ETT POSITION AND ESOPHAGEAL INTUBATION
An ideal method or device, a “silver bullet” to detect successful endotracheal intubation, does not exist. Even properly placed ETTs may become displaced at any time; therefore constant vigilance and a need for reconfirmation of tube position may be needed. No technique for confirmation of endotracheal intubation is 100% reliable in all circumstances.
Incidence of ETT malposition at the time of intubation or as a result of dislodgment after placement has been reported between 4% to 26% . Almost any practitioner who has attempted endotracheal intubation has experienced incidents of EI(Esophageal intubation). This is for the most part harmless; Not recognizing it promptly can cause harm.
- Endotracheal tube visualization– Operator dependent, and does not exclude dislodgement after placement. Less accurate in cases of difficult laryngoscopy with a limited view of the glottic opening, as a result of anatomic distortion or the presence of secretions, vomitus, or blood.
- Auscultation – Routine auscultation at one or two points on each side of the chest and over the epigastrium is recommended to establish proper ETT placement and position. However, auscultation was reported as normal in 48% of cases of esophageal intubation reported by ASA closed claims analysis. Normal breath sounds can be transmitted to the epigastric area, and gastric sounds can be transmitted to the chest wall, resulting in false-negative and false-positive readings, respectively. Similarly, esophageal sounds can be transmitted to chest and interpreted as breath sounds. Furthermore, auscultation is also observer dependent.
- Condensation in endotracheal tube- Cases of ETT humidification despite EI have been reported, as well as animal studies have shown that condensation can be noted even with esophageal intubation. This method should not be used alone, rather than some as a supplement to other examination.
- Abdominal distension and chest wall movement- Can be used in conjunction with the above methods in normal circumstances. However, in the obese, obstetric population, patients with large breasts, patients with chest wall pathology, or when there is an alteration of lung compliance, neither abdominal distention nor chest wall movement is a reliable clinical sign of adequate ETT placement.
SECONDARY ENDOTRACHEAL DETECTION TECHNIQUES
- Carbon dioxide detection in exhaled gases- Exhaled CO 2 detection is the most accurate method to evaluate ETT position in patients who have adequate tissue perfusion. When CO 2 is absent as measured by end-tidal capnography, it either means the ETT is in the wrong position (EI) or there is absent or low pulmonary blood flow, as can occur during shock, cardiac arrest, or cardiopulmonary resuscitation (CPR) with inadequate chest compressions. Exhaled CO 2 can be measured by colorimetry, capnometry, and capnography.
- Colorimetric devices have a paper which is pH-sensitive indicator that changes color when exposed to CO 2 . Purple with air, Tan with CO2. They are considered less accurate compared with waveform capnography.
- Quantitative devices measure CO2 in exhaled air and display either in form of graph or a number. There is normally a 0- to 5-mm Hg gradient between exhaled CO 2 and the arterial concentration of CO 2 (Pa co 2 ), which corresponds to the alveolar dead space. Waveform capnography is considered most reliable method to confirm and monitor ETT placement. If the ETT has been placed in the hypopharynx, a normally appearing waveform may be present for a few breaths, but it becomes erratic with next breaths. A flat line capnography suggest esophageal intubation. Several conditions can produce a flat line capnography, and include cardiac arrest; inadequate pulmonary blood flow, as can occur with poor chest compressions during CPR; severe bronchospasm; ETT obstruction attributed to a foreign body, blood clot, or large mucous plug; and malfunction of the monitor or tubing. However, one should never assume a flat line capnography is due to above reasons and confirm the ETT position by other methods as well. In patients not in cardiac arrest, the use of qualitative colorimetric and quantitative exhaled CO 2 detection has been reported to be 100% sensitive and 100% specific for confirming ETT. In patients with cardiac arrest, sensitivity may drop up to 62%. In all patients, but specifically in patients in cardiac arrest, alternative objective methods for ETT placement and position should be used because there are known limitations to detection of exhaled CO 2.
- Esophageal detector device- It is a self-inflating bulb with a capacity of 75 to 90 mL. After intubation, the device, fitted with a standard ETT adapter, is connected to the ETT, and the bulb is compressed. If the ETT is in the trachea, inflation of the bulb will occur; if the ETT is in the esophagus, the bulb will remain collapsed. False negative results have been reported when the device fails to detect intubation in the trachea. False negative results are mainly seen in patients with morbid obesity, obstetrics patients, and in presence of ARDS, severe bronchospasm and pulmonary edema.
- Transtracheal illumination- Lighted stylet when placed in a endotracheal tube which is in trachea, emit an intense, midline glow in the anterior neck above the suprasternal notch. if the endotracheal tube is in esophagus, this glow will be absent. However, this method is considered unreliable as a sole indicator for successful intubation.
- Pulse oximetry- it is not a confirmatory test but is part of basic respiratory monitoring, which can provide valuable information. Desaturation, as indicated by pulse oximetry, is a relatively late manifestation of incorrect ETT placement. Normal pulse oximetry readings immediately after intubation should not be taken as evidence of successful endotracheal intubation. It must be complemented by other primary and secondary methods of confirmation of endotracheal intubation, particularly the detection of expired CO 2.
- Chest radiography- is mainly used to assess proper depth, rather than confirmation in trachea. It is time consuming, and therefore cannot be used for immediate confirmation. It is not also full proof. Ideally, 25 degrees right posterior oblique position can detect about 92% of esophageal intubations. It is hard to find images of chest x-ray showing esophageal intubation as it is not used primarily for this purpose.
- Ultrasonography- It is portable, safe, and quick and allows dynamic real-time visualization, no limitations of use in noisy environments. ETT can be directly seen in trachea or esophagus by USG. Furthermore, one can see bilateral lung sliding and equal diaphragmatic movement as well. However, it is observer dependent. Sensitivity of real-time imaging is higher than determining placement after intubation. The use of USG or any other technique as a sole test for detection of esophageal intubation is not recommended.
- Flexible bronchoscopy – It is gold standard method for confirming proper ETT placement and position; it is the only direct method. Largest obstacle to its use is the cost, training and availability.
A combination of techniques should be used for confirmation of tracheal tube placement. Primary detection methods should be complemented by secondary confirmatory techniques. Detection of exhaled CO 2 by waveform capnography is considered the most sensitive method to confirm that the ETT is in the respiratory tract.