Questions and Answers
Which factors decrease physiologic dead space? (Select all that apply)
Which hypertonic crystalloid solution includes D5 0.45NS?
Which cells in the islets of Langerhans produce somatostatin?
Which congenital heart diseases are associated with right-to-left shunt? (Select all that apply)
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Carbonic anhydrase inhibitors are used in the treatment of which condition?
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In a patient requiring pneumonectomy, split lung function testing is indicated if they have:
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Which statements regarding renal blood flow are true? (Select all that apply)
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Study Notes
Dead Space Physiology
- Dead space includes anatomical dead space (non-respiratory airways) and alveolar dead space (unperfused alveoli).
- Factors decreasing physiologic dead space: supine position.
- Factors increasing physiologic dead space: anticholinergic agents, β2-sympathomimetics, increasing age, and COPD.
Hypertonic Crystalloid Solutions
- Normal plasma osmolality: 280 - 290 mOsm/L.
- D5W is hypotonic (253 mOsm/L).
- Isotonic solutions: Ringer's Lactate (273 mOsm/L) and D5 0.25NS (355 mOsm/L).
- D5 0.45NS is hypertonic (406 - 432 mOsm/L).
Islets of Langerhans Cell Types
- Four cell types in islets:
- Alpha cells: produce glucagon.
- Beta cells: produce insulin.
- Delta cells: produce somatostatin.
- PP cells: produce pancreatic polypeptide.
Right-to-Left Shunt Congenital Heart Diseases
- Cyanotic congenital heart diseases associated with right-to-left shunt:
- Tricuspid atresia.
- Hypoplastic left heart syndrome.
- Tetralogy of Fallot.
- In tricuspid atresia, blood exits the right atrium only via patent foramen ovale (PFO).
Carbonic Anhydrase Inhibitors
- Indicated for: acute glaucoma.
- Mechanism: reduce bicarbonate reabsorption by kidneys, leading to hyperchloremic acidosis.
- Inhibit aqueous humor formation, decreasing intraocular pressure.
Pneumonectomy and Lung Function Testing
- Split lung function testing recommended in patients with specific criteria before pneumonectomy.
- Key indicators:
- PaCO2 should be < 45 mm Hg.
- FEV1 should exceed 2 L.
- Predicted postoperative FEV1 > 800 mL.
- Maximum VO2 > 15 mL/kg/min.
Renal Blood Flow Characteristics
- Accounts for 20 - 25% of cardiac output.
- Distribution: primarily to cortical nephrons (80%) and juxtamedullary nephrons (10 - 15%).
- Blood flow can be redirected away from cortical nephrons by sympathetic stimulation.
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Description
Explore the complexities of dead space physiology, the effects of hypertonic crystalloid solutions, the function of the Islets of Langerhans, and congenital heart diseases associated with right-to-left shunting. This quiz will test your knowledge across these critical medical concepts.
