Hemoglobin and Hematocrit Quiz

Hemoglobin and Hematocrit

• Normal adult males have a hemoglobin content of 13.5-16.5 g/dl and a hematocrit of 40-54%.
• Normal adult females have a hemoglobin content of 12-15 g/dl and a hematocrit of 38-47%.

Oxygen Saturation and Hemoglobin

• Oxygen saturation changes the shape of the hemoglobin molecule, turning it bright red.
• Releasing oxygen desaturates the hemoglobin, changing its shape and turning it a darker red or purple.

Cyanosis

• Cyanosis is apparent when capillary blood contains more than twice the normal amount of reduced hemoglobin (about 5-6 g/dl).
• 5 g/dl of reduced hemoglobin is produced when SaO2 drops to about 85%, equivalent to PaO2 of about 50 mm Hg.
• Normal people have about 2 g/dl of reduced hemoglobin in their blood.

Pulsus Paradoxus

• Pulsus paradoxus is a palpation finding characterized by a pulse that is simultaneously slight and irregular, disappearing during inspiration and returning during expiration.
• It is defined as a decrease in systolic arterial pressure of >10 mmHg during spontaneous inspiration.
• The exact physical mechanism of pulsus paradoxus is unknown, but one theory suggests:
  • Changes in intrathoracic pressure during spontaneous breathing affect the heart and great vessels.
  • During inspiration, the right ventricle distends due to increased venous return, causing the interventricular septum to bulge into the left ventricle.
  • This reduces the left ventricular stroke volume, resulting in decreased blood ejected with each beat.