![]() ![]() In the past five years, though, newer techniques were developed that allowed the accurate measurement of CO 2 in expired air even in neonates.16 One such example is the development of Microstream technology which could measure expiratory CO 2 accurately in infants and children.24,25 Secondly, the information on capnography in pediatric practice is scattered in the pediatric literature, and a comprehensive paper describing applications and limitations of capnography in pediatric practice is currently lacking. First, capnography in pediatric patients is viewed skeptically due to limitations in obtaining accurate measurements of CO 2 in expired air. Therefore, the value of capnography has recently been recognized in pediatric care, and its use is progressively increasing in pediatric and neonatal intensive care units,15-23 However, the potential diagnostic and therapeutic abilities of capnography are not often recognized, and thus capnography is not used as often as would seem indicated.18 This may be due to two reasons. Further, in conjunction with ABG analysis, capnography can provide information about ventilation/perfusion (V/Q) disturbances in the lung. It also generates valuable information regarding the mechanical and gas exchanging functions of the child's lungs. For example, it serves as a reliable and instantaneous apnoea monitor. It provides continuous surveillance of arterial CO 2 tensions and provides information which is not obtainable from ABG's or PtCO 2's alone. In contrast, capnography is not associated with any deleterious effects. However, unlike pulse oximetry sensors, the heated electrodes of transcutaneous CO 2 sensors are associated with complications such as burns in the neonate, damages to the skin by adhesive, excessive drift of electrodes, erratic behavior in the presence of acidosis, long calibration and stabilization intervals and the need to change the sensor every 2-4 h.10-14 These effects are more pronounced in infants with decreasing gestational age. Therefore noninvasive monitors such as pulse oximetry to determine oxygenation, and transcutaneous CO 2 (PctCO 2) monitoring and end-tidal CO 2 monitoring (capnography) to monitor the CO 2 status of critically ill infants and children have become increasingly popular.9 They have lessened the need for invasive monitoring with indwelling catheters, with the subsequent reduction in complications due to transfusions, infections and vascular events. ABG's provide intermittent, not continuous data, which limits its use in documenting transient events. ![]() Further, ABG's have inherent fallacies such as the amount of heparin, the amount of time before analysis, and hyperventilation due to pain or breath holding if the child cries during percutaneous sampling. ABG's require either a painful, time consuming procedure or an invasive arterial line to obtain a specimen for evaluation. While ABG's remain the gold standard, limitations also exist. In the past, the only method to quantify the adequacy of ventilation and oxygenation was by assessment of arterial blood gas (ABG). The American Academy of Pediatrics (Committee on hospital care, 1991-92) has issued 'minimum guidelines and levels of care' required for pediatric intensive care units as a means of ensuring proper patient care and professional creditability.8 The guidelines require CO 2 and oxygen (O 2) monitoring be performed on all patients receiving care in level I and II pediatric critical care centers. Pediatric critical care medicine has matured dramatically over the last two decades. In the last two decades, measurement of carbon dioxide (CO 2) in the expired air (capnography) has become increasingly popular in the operating room to monitor patients during anesthesia.1 Its use is strongly recommended in every patient requiring endotracheal intubation,2,3 because capnography can instantaneously identify potentially life threatening conditions such as failed intubation, failed ventilation, failed circulation, and failed circuits before irreversible damage is done to the patients.1,4,5 While the anesthesiologists have appreciated the value of capnography in the last decade, physicians in other specialties are beginning to appreciate its value as a reliable diagnostic, and monitoring aid.6,7 Bhavani Shankar Kodali MD For physics and physiology of capnography, refer to appropriate sections. ![]()
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