Respiratory Physiology: VQ Mismatches and Disorders

Flashcards covering key vocabulary related to VQ mismatches, respiratory physiology, and common pulmonary disorders from the lecture notes.

VQ Mismatches

Imbalances in the ventilation perfusion relationships, referring to the amount of air reaching the alveoli and the amount of blood flow in the capillaries.

Normal Alveolar Ventilation

Approximately 4 liters per minute.

Normal Capillary Blood Flow

Approximately 5 liters per minute.

Overall Average VQ Ratio

The ratio of normal alveolar ventilation to normal capillary blood flow, which is 4:5 or 0.8.

Respiratory Quotient (RQ)

The ratio between the volume of carbon dioxide produced (VCO2) and the volume of oxygen consumed (VO2), normally 0.8 in healthy patients.

Respiratory Exchange Ratio (RER)

The quantity of oxygen and carbon dioxide exchanged during a period of one minute; normally equal to the Respiratory Quotient.

External Respiration

The process of gas exchange that occurs between the pulmonary capillaries and the alveoli.

VQ Ratio in Upright Lower Lung Regions

Tends to be lower than 0.8 due to greatly increased blood flow compared to ventilation caused by gravity.

VQ Ratio in Upright Upper Lung Regions

Tends to be higher than 0.8 due to less blood flow compared to ventilation caused by gravity.

Decreased VQ Ratio Effects

A condition resulting in alveolar partial pressure of oxygen (PAO2) falling and alveolar partial pressure of carbon dioxide (PaCO2) rising.

Semi-Fowler's Position

A bed position with the head of the bed elevated at least 30 degrees, commonly used to prevent aspiration in patients, especially those on ventilators.

Ventilator-Associated Pneumonia (VAP)

A serious lung infection that develops in patients receiving mechanical ventilation, often preventable through specific care bundles.

VAP Bundles

A set of evidence-based interventions designed to prevent ventilator-associated pneumonia, including oral care, blood sugar management, and reflux medication.

Diagnosis-Related Groups (DRGs)

A classification system used by Medicare and other insurers to group hospital cases for payment purposes, impacting hospital reimbursement based on primary diagnosis.

Pulmonary Emboli

A blockage in the pulmonary arteries, often by a blood clot, which can increase the VQ ratio due to low perfusion.

Obstructive Lung Disorders

A group of respiratory diseases (e.g., emphysema, bronchitis, asthma) characterized by reduced airflow due to airway obstruction, described as 'obstructive to flow' in PFTs.

Restrictive Lung Disorders

A group of respiratory diseases (e.g., pneumonia, pulmonary fibrosis) characterized by reduced lung volume, described as 'restrictive to volume' in PFTs.

CBAVE (mnemonic)

An acronym representing common obstructive lung disorders: Cystic Fibrosis, Bronchiectasis, Asthma, Bronchitis, and Emphysema.

Shunt Unit

An alveolar unit where blood flow occurs but there is little or no ventilation, leading to unoxygenated blood bypassing gas exchange; not effectively treated with 100% oxygen.

Dead Space Unit

An alveolar unit that is ventilated but has no blood flow, meaning gas exchange cannot occur; characterized by high PAO2 (150) and zero PaCO2.

Venous Admixture

The mixing of deoxygenated blood (from shunts or unventilated areas) with oxygenated blood returning to the heart, leading to a reduction in the overall oxygen content of arterial blood.