Use of Disposable End Tidal Carbon Dioxide Detector Device for Checking Endotracheal Tube Placement.
Correspondence Address :
Department of NEWBORN CARE, Liverpool Hospital, Liverpool, NSW 2170, Australia
Corresponding Author: Dr Hemant Jain
End tidal carbon dioxide (ETCO2) monitoring is the non-invasive measurement of exhaled CO2. It is of particular use for verification of endotracheal tube placement. It is easy to apply to breathing circuits. This technology has the potential to become a very useful tool in the pre-hospital setting. It is a commercially available, disposable, colorimetric ETCO2 detector in which colour changes using a numerical scale semi-quantitatively measures carbon dioxide percentage in exhaled gases, and it has been proved useful in adults and children. End tidal CO2 detectors provide an objective evidence of the tube position in the trachea. In addition to quickly revealing the misplaced oesophageal intubations it can prevent unnecessary re-intubations. Other uses in the Emergency Department include monitoring CPR efforts and monitoring the ventilatory and haemodynamic status of intubated and nonintubated patients. In addition, future uses may include using PetCO2 as an adjunct when monitoring the status of asthma treatment, when making the diagnosis of pulmonary embolism, and when measuring cardiac output noninvasively.
End tidal carbon dioxide detector, neonates, emergency medicine, endotracheal intubation, cardiopulmonary resuscitation
Endotracheal intubation remains one of the critical skills for all concerned with emergency and intensive care. In life-threatening situations in the operating room, intensive care unit, emergency department and in the pre-hospital setting, endotracheal intubation is a commonly performed emergency procedure. It is not uncommon for young registrars to face this challenge in the delivery room. Bag and mask ventilation is an intervention that is performed in up to 10% of delivery room resuscitations in newborn infants (1). Catastrophic situations like inadvertent, undetected oesophageal intubation can occur in the hands of the most experienced people (2)(3)(4). Similarly, senior staff often needs reassurances with regards to intubation skills of the junior staff. Clinical methods of determining the tube placement are usually good enough for an experienced operator. However, there can be circumstances when opinions may vary between the nursing and medical staff regarding the tube placement. If the oxygen saturation increases quickly there is little to doubt, though at times this may not happen soon. In those precious moments, lot of confusion can arise when the tube placement is in doubt. Similarly, it is difficult for a specialist on call who is contacted through the telephone to judge whether the intubation has been correctly performed or not. End tidal CO2(ETCO2) detectors provide an objective evidence of tube position in the trachea. This can prevent unnecessary re-intubations and can quickly reveal the misplaced oesophageal intubations.
The usual clinical methods used for confirming endotracheal tube (ETT) position, such as bilateral breath sound auscultation, chest movement visualization, clouding of the ETT, auscultation over the stomach, etc., occasionally fail. Since CO2 which is exhaled through the trachea, is not usually detected in the oesophagus, capnometry can distinguish between endo-tracheal and oesophageal intubation. In the early detection of oesophageal intubation measurement of ETCO2 has been shown to be superior to pulse oximetry, especially in patients who are pre-oxygenated with 100% oxygen (5).
CO2 which is produced during cellular metabolism, is transported to the heart and exhaled via the lung, and so ETCO2 is a reflection of ventilation, metabolism and circulation. By keeping any two systems constant, changes in the third system are found to reflect changes in ETCO2. Hence, it is a non-invasive technique to evaluate these systems (3)(4). ETCO2 is increased in hyper-metabolic states such as sepsis, malignant hyperthermia, shock and pulmonary embolism. Decreased cardiac output and decreased pulmonary blood flow during cardiopulmonary resuscitation (CPR) cause decreased ETCO2 (6). In anaesthesia practice, ETCO2 monitoring is has become a standard of care. The normal ETCO2 is approximately 38 mm Hg (a 5% concentration at 760 mm of atmospheric pressure). In patients with normal perfusion and ventilation, ETCO2 measurement closely resembles arterial CO2 partial pressures(7)(8).
A non-toxic, pH-sensitive chemical indicator (metacresol purple) visible through a clear dome, detects CO2 in gas mixtures flowing through it. Concentrations of CO2 are indicated by reversible colour changes. The detector turns yellow during expiration and purple during inspiration, when it is attached to the ETT of a correctly intubated patient. When attached to an ETT placed in the oesophagus, it remains purple. Colour ranges are visible through the dome. The device which works for about 2 hours, responds to breath-by-breath CO2 changes. Increased humidity can decrease the clinical lifespan of<
Using the portable device allows much faster detection of erroneous intubation and much earlier reintubation, and this is of particular benefit to babies who are erroneously intubated in the esophagus. It is useful where the operators are less experience, in pre-hospital setting and in reconfirmation of ET position on an infant on ventilatory support. It is a handy piece of equipment which should be a part of all resuscitation trolleys.
Conflict of Interest : None.
Source of Funding: None.
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