NONPULMONARY FACTORS
Abnormalities other than alterations in lung function may influence the Pao2 through their effect on the mixed venous Po2(Py02). The Pv02 is decreased when cardiac output is inappropriately low, when 02 consumption (Vo2) is increased (as with exercise or fever), or when the hemoglobin concentration or 02 saturation is low. For any lung unit, the resultant end-capillary Po2 is influenced by the Pvo2, although the magnitude of this effect on the arterial 02 content will be greatest in lungs with Va/Q inequality or shunt (Fig. 17-9). The importance of this phenomenon is the recognition that a fall in Pao2 in a patient with lung disease may be due to one of these nonpulmonary factors rather than a deterioration in lung function, thus requiring a very different intervention.
- MISCELLANEOUS AORTIC DISEASE
- ARTERIAL TRAUMA
- PERIPHERAL VENOUS DISEASE
- PERIPHERAL ANEURYSMS AMD FISTULAE
- ENVIRONMENTAL DAMAGE OF THE EXTREMITIES
- THE AIRWAY STRUCTURE
- GENERAL SURGERY IN THE PATIENT WITH HEART DISEASE
- GENERAL PRINCIPLES OF CARDIAC SURGERY
- HEART DISEASE AND PREGNANCY
- THE BLOOD VESSELS STRUCTURE
- THROMBOANGIITIS OBLITERANS
- PULMONARY GAS EXCHANGE
- NONPULMONARY FACTORS
- VENTILATION
- GAS TRANSFER
- PERFUSION
- NONRESPIRATORY FUNCTIONS OF THE LUNG
- ARTERIOSCLEROSIS OBLITERANS
- RAYNAUD'S PHENOMENON