Physiological Consequences of Increased Movement of Fluid Flashcards
What is the pulmonary arterial pressure?
15mmHg
What is the pulmonary capillary pressure?
12-8 mmHg
What is the pulmonary capillary volume at rest?
60-80mL
Why does pulmonary arterial pressure not increase as cardiac output increases?
Because of dilation of pulmonary vessels and also possible recruitment of vessels that are normally not being perfused
What is the change in systemic blood pressure with respiration relative to?
The size of the negative intrapleural pressure
What causes kerley B lines on a CXR?
dilated lymphatics
What does low PaCO2 in blood gases indicate with low pH?
Metabolic acidosis - CO2 is low due to compensatory hyperventilation in attempt to increase pH
What causes metabolic acidosis in heart failure?
Tissues undergoing anaerobic metabolism generating acid because they are hypoxic
What causes low bicarbonate in metabolic acidosis?
Either bicarbonate is being lost for a reason (such as diarrhoea) or it is being consumed to act as a buffer for an acid (such as lactic acid in hypoxia or ketoacid if diabetic etc.)
What is the normal concentration of HCO3-?
22 to 28 mmol/L
What does low PaCO2 in blood gases indicate with high pH?
respiratory alkalosis
What are the causes of pulmonary oedema?
Increase in hydrostatic pressure or increased vascular permeability
What are the mechanical changes that occur in pulmonary oedema?
decrease in lung complicance, decrease in lung volume, increase in airway resistance, increased work of breathing (both elastic and resistive)
What are the blood gasses in pulmonary oedema?
low PaO2, low PaCO2, high pH - due to compensatory hyperventilation
What are the blood gasses in severe pulmonary oedema?
low PaO2, high PaCO2, low pH - if in metabolic and respiratory acidosis - fatigue so can no longer hyperventilate
