motion while a simplified ECG tracks cardiac electrical activity. Thresholds for
rate alarms may be set to notify care providers. When combined with continuous
pulse oximetry, these tools are effective at notifying clinicians of impending
compromise. Simple stimulation of the infant is often sufficient to address an
apnea episode, though more definitive airway control may be required.
C. Capnography (Figure of normal capnogram)
Continuous monitoring of expired C0 2 has become the standard of care in
anesthetic management and is rapidly proliferating in the ICU environment. In
principle, the detected CO 2 levels at the end of respiration should reflect alveolar
CO 2 concentration. In turn, this may be considered a surrogate for systemic
arterial PCO 2 levels. In practice, ventilation/perfusion mismatch, timing of
emptying of regions of lung, and lung disorders lower the detected values and
limit the utility of the absolute value obtained in capnometry. However, trends in
the capnometric measurement may be interpreted to reflect changes in
endogenous C0 2 production, minute ventilation, expiratory restriction, and
effective pulmonary perfusion as described in the examples below:
- One of the earliest indicators of malignant hyperthermia (a
hypermetabolic state) is rising end-tidal CO 2 (ETCO 2 ). - As lung compliance improves in states such as ARDS, increased
tidal volumes may result in falling ETCO 2.