![]() ETCO 2 values (mm Hg) during anaesthesia with spontaneous ventilation Monitors display the peak ETCO 2 value, respiratory rate, and usually inspired CO 2 value. D = the next inspiration - inspired gas should not contain CO 2. An alveolar gas "plateau" may not be obtained in animals with small tidal volumes (e.g., cats). ![]() This should correspond to the arterial PaCO 2 in animals that don't have lung disease. A continuous wave form can be generated which will demonstrate three phases of expiration during each respiratory cycle: A = dead space gas with no CO 2 B = mixed gas with rising CO 2 C = alveolar gas with a CO 2 plateau from which the ETCO 2 peak value is read. End tidal CO 2 (ETCO 2) monitors continuously sample gas at the endotracheal connector and measure the CO 2 partial pressure using proportional absorption of infra-red light. Circle system resistance is increased by unidirectional valves, the absorber, and high respiratory rates and tidal volumes.Methodology: As anaesthetic depth increases, ventilatory function (minute ventilation = respiratory rate x tidal volume) decreases and therefore CO 2 increases in a dose-dependent fashion. ![]() Resistance to breathing-Resistance is always high with turbulent flow, hence narrow diameter tubing and orifices, sharp bends, increasing circuit length, and eliminating unnecessary valves that produce this should be avoided in the apparatus. Hence, to avoid hypercarbia in the face of an acute increase in dead space, a patient must increase minute ventilation. Increasing the dead space increases rebreathing of carbon dioxide. The elbow, the heat and moisture exchanger (HME), and the D-lite sensor contribute to real apparatus dead space where part of V T does not participate in gas exchange. ![]() Dead space-In the circle systems, the tubing (mechanical) dead space ends at the point where inspired and expired gas streams meet at the Y-connector, resulting in loss of tidal volume ( V T) from the compliance of the distensible corrugated inspiratory and expiratory tubing and from gas compression. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |