Kapnografiya is a method of tool monitoring which consists in measurement of concentration of carbon dioxide on a breath and on an exhalation. Distinguish a kapnometriya — measurement of concentration of carbon dioxide on a breath and on an exhalation and display of results of measurement in the form of figures, and a kapnografiya — display on the screen of concentration of carbon dioxide on a breath and on an exhalation in the form of the special schedule. The second type of monitoring is preferable. There is also a method of a qualitative kapnometriya when carbon dioxide is found in the exhaled mix on change of coloring of the special indicator, but in this case exact concentration of carbon dioxide on an exhalation is unknown.
Kapnografiya is the obligatory standard of anesthesiology monitoring now. The qualitative kapnometriya can be used in the conditions of a pre-hospital stage for confirmation of arrangement of an endotracheal tube.
The principle of a method consists in measurement of concentration of carbon dioxide by means of use of infrared radiation which carbon dioxide absorbs in a limited range. The technology consists in use of comparison of the studied air with a check sample in which concentration of carbonic acid is known. On the basis of measurement the schedule of the relation of concentration of carbon dioxide at the right time which is output to the user in the form of the image of a kapnogramma is under construction. Display of concentration of carbon dioxide can be applied in various sizes, but millimeters of mercury are most often used. Distinguish a kapnometriya in a direct stream when the sensor is directly in a rebreathing system and in a side stream when from a rebreathing system there is a selection of a sample of air of small volume which comes to the analyzer subsequently. The second method is more universal as it can be used both at intubated, and at not intubated patients.
In the analysis of a kapnogramma consider as actually concentration of carbon dioxide on a breath and on an exhalation, and a form of a kapnografichesky curve.
Normal concentration of carbon dioxide on a breath has to be equal in respiratory mix to zero. If on a breath there is carbon dioxide, then it testifies most often to adsorbent exhaustion in a contour of the narcotic device. Considerable concentration of carbon dioxide on a breath can demonstrate to serious emergency situations and technical malfunctions in the system of supply of gases, for example that carbon dioxide comes to a rebreathing system.
Normal at the patient a certain concentration of carbon dioxide decides on sufficient warm emission and without disturbances of the ventilating and perfusion relations in lungs on an exhalation. This fact serves justification for wide use of a kapnografiya as a tool marker of confirmation of provision of an endotracheal or tracheostomy tube. If the tube is established correctly and is in a trachea, in expired air carbon dioxide is defined and on the screen the kapnografichesky curve of the correct form is displayed. If the tube is not in a trachea (and, for example, in a gullet), then carbon dioxide on an exhalation either is not defined in general, or is defined at first in insignificant quantity, and through several respiratory cycles completely disappears or is at very low level. This fact allows to distinguish in due time by means of use of a kapnografiya an intubation of a gullet and to take urgent measures.
Increase in concentration of carbon dioxide on an exhalation is noted at a hyperthermia, a hyper dynamic stage of septic shock and also at hypoventilation. Sharp increase in concentration of carbon dioxide on an exhalation to considerable figures can be a signal of development in the patient of a malignant hyperthermia.
Decrease in concentration of carbon dioxide on an exhalation is noted at a hyperventilation, disturbance of the ventilating and perfusion relations, disturbances of a hemodynamics. Sharp falling of concentration of carbon dioxide on an exhalation can demonstrate sharp falling of warm emission, for example, at a stop of warm activity.
As it was already told, in addition to actually value of concentration of carbon dioxide on an exhalation, also form of a kapnografichesky curve is important. Emergence of a two-humped curve testifies to a bronchial tube intubation. Separate peaks on a curve can speak about restoration of neuromuscular conductivity. The ascending kapnogramma knee at obstruction of respiratory tracts has more flat form.
When using a kapnografiya it is important to remember that the technical serviceability of a kapnograf and its regular calibration is of great importance for obtaining the correct results.