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# TABLE 7-2 CONDITIONS ASSOCIATED WITH CHANGES IN PETCO2 | Change | High PETCO2 | Low PETCO2 | |---|---|---| | **Gradual** | Hypoventilation Increase CO2 production Partial airway obstruction Increased muscular activity (shivering) Effective drug therapy for bronchospasm | Hyperventilation Dec...

# TABLE 7-2 CONDITIONS ASSOCIATED WITH CHANGES IN PETCO2 | Change | High PETCO2 | Low PETCO2 | |---|---|---| | **Gradual** | Hypoventilation Increase CO2 production Partial airway obstruction Increased muscular activity (shivering) Effective drug therapy for bronchospasm | Hyperventilation Decrease in oxygen consumption Decreased in pulmonary perfusion Decreased muscular activity (muscle relaxation) Hypothermia Bronchospasm | | **Sudden** | Bronchial intubation Sudden increase in cardiac output Sudden increase in blood pressure Sudden release of a tourniquet Injection of sodium bicarbonate Malignant hyperthermia CO2 embolism | Sudden hyperventilation Sudden decrease in cardiac output Massive pulmonary embolism Air embolism Disconnection of ventilator Accidental extubation Leakage in the circuit | # BOX 7-2 INDICATIONS, HAZARDS & POTENTIAL COMPLICATIONS OF CAPNOGRAPHY ## BOX 7-2 Indications, hazards, and potential complications of capnography. ### Indications * Verification of artificial airway placement (determining that tracheal, rather than esophageal, intubation has been accomplished) * Assessment of pulmonary circulation and respiratory status * Improve the matching of V/Q * Measurement of the volume of CO2 elimination to assess metabolic rate or alveolar ventilation * Optimization of mechanical ventilation * Improve the Vd/Vt ratio * Continued monitoring of the integrity of the ventilatory circuit, including the artificial airway ### Hazards and Potential Complications * Evaluation of the efficiency of mechanical ventilatory support (by determining the (a-1) PCO2 gradient) * Misunderstanding of the data provided may lead to inappropriate treatment of the patient * With mainstream analyzers, too large a sampling window can excessively increase the circuit mechanical dead space * The sampling window or the sampling lines can place additional weight on the circuit and increase traction on the patient's artificial airway (primarily a concern in young pediatric patients) * With sidestream analyzers, the sampling rate may cause auto-triggering of mechanical ventilators **Note:** PETCO2 refers to end-tidal carbon dioxide partial pressure. V/Q refers to the ventilation-perfusion ratio. Vd/Vt refers to dead space to tidal volume ratio.