gas exchange Flashcards
pulmonary gas exchange steps
step 1: ventilation
step 2: respiration.
step 3: transport of gases in the circulation
reasons for V/Q < 0.8
a) A decrease in ventilation in relation to perfusion has occurred.
b) Similar to right to left shunt
c) Mucous plug
reasons V/Q > 0.8
a) a decrease in perfusion in relation to ventilation
b) pulmonary emboli, cardiogenic shock
PaO2 normal range
SaO2 normal range
When do patients have hypoxemia
what level of PaO2 is life threatening
PaO2: 80-100
SaO2: 95-100%
HYPOXEMIA: PaO2 <60
PaO2 <40 is life threatening
explain shunting in the lung
Blood shunted past the lung and returns unoxygenated blood to left side of heart
causes of shunting
AVMs, ARDS, atelectasis, pneumonia, pulmonary edema, pulmonary embolus, vascular lung tumors, intra-cardiac right to left shunts
causes of metabolic alkalosis
-vomiting
-NG suctioning
-diuretic therapy
-hypokalemia
-excess NaHCO3 intake
-mineralocorticoid use
clinical manifestations of metabolic alkalosis
-irritability, lethargy, confusion, headache
-tachycardia, dysrhythmias r/t hypokalemia
-nausea, vomiting, anorexia
-tetany, tremors, tingling of fingers and toes, muscle cramps, hypertonic muscles, seizures
-hypoventilation
management of metabolic alkalosis
treat underlying cause
causes of respiratory alkalosis
-hyperventilation (hypoxia, anxiety, pain, fever, exercise)
-stimulated respiratory center (septicemia, stroke, meningitis, encephalitis, brain injury, salicylate poisoning)
-liver failure
-mechanical hyperventilation
clinical manifestation of respiratory alkalosis
-dizziness, confusion, headache
-tachycardia, dysrhythmias r/t hypokalemia
-nausea, vomiting, diarrhea, epigastric pain
-tetany, numbness, tingling of extremities, hyperreflexia,
seizures
metabolic compensation for respiratory alkalosis
decreased hydrogen secretion and bicarbonate reabsorption
management of respiratory alkalosis
-discontinue or treat underlying cause
-decrease excessive ventilation if possible (hyperventilation-encourage breath holding, breath into paper bag)
-if acute hypoxemia, oxygen therapy
causes of metabolic acidosis
-diabetic ketoacidosis
-Lactic acidosis
-Starvation
-Diarrhea
-Renal tubular acidosis, renal failure
-GI fistulas
-Shock/sepsis
clinical manifestation. of metabolic acidosis
- lethargy, confusion, dizziness, headache, coma
-hypotension, dysrhythmias (r/t hyperkalemia), cold/clammy skin
-warm, flushed skin (peripheral vasodilation)
-nausea, vomiting, diarrhea, abd pain
-deep, rapid respirations
respiratory compensation for metabolic acidosis
increased respiratory rate and depth (Kussmaul respirations)
management of metabolic acidosis
-treat underlying cause
–administer sodium bicarbonate (extreme metabolic acidosis pH<7.1
-treat DKA with insulin and IV fluids
-decrease acid formation (decrease lactic acid production by improving CO in shock)
-treat kidney disease or toxic medication with dialysis
causes for respiratory acidosis
-Chronic respiratory disease (respiratory failure related to: COPD, ARDS, severe asthma)
-Barbiturate or sedative overdose
-CNS depression (head trauma, anesthesia, barbiturate or sedative overdose, oversedation, high spinal cord injury)
-Chest wall anomaly, atelectasis, pneumothorax
-Severe pneumonia
-Respiratory muscle weakness (myasthenia gravis, multiple sclerosis)
-Mechanical ventilation hypoventilation
-Pulmonary edema
clinical manifestation of respiratory acidosis
-drowsiness, lethargy, confusion, dizziness, headache
-hypotension, ventricular fib (r/t hyperkalemia), warm flushed skin
-seizures
-decreased respiratory rate and depth of breathing, hypoxia
renal compensation for respiratory acidosis
-increased hydrogen secretion and bicarbonate reabsorption
management of respiratory acidosis
-correct/improve ventilation and lung expansion
(supplemental oxygen, bronchodilators, cough & deep breath, incentive spirometry, ambulation, BiPAP or CPAP, intubation with mechanical ventilation)
-treat underlying cause
-chest physiotherapy, suctioning to clear secretions
