Medical Gas Therapy: Introduction to Oxygen Therapy

Vocabulary practice flashcards covering terminology, physiological values, hazards, and delivery systems from the medical gas therapy lecture on oxygen administration.

FiO2 (Fraction of Inspired Oxygen)

The concentration or fraction of oxygen present in any gas mixture, expressed as a percentage (such as $21\%$) or as a decimal (such as $0.21$).

PaO2

The partial pressure of oxygen in arterial blood, measured in Torr or millimeters of mercury ($\text{mmHg}$).

PaCO2

The partial pressure of carbon dioxide in arterial blood, measured in Torr or millimeters of mercury ($\text{mmHg}$).

Cyanosis

A bluish discoloration of the skin or oral mucosa, visible around areas such as the mouth, nose, or nail beds.

Hypoxemia

An abnormally low level of oxygen in arterial blood, defined in adults as a $\text{PaO}_2$ less than $55\text{ to }60\,\text{mmHg}$ or an $\text{SpO}_2$ less than $87\text{ to }90\%$ on room air.

Hypoxia

An abnormally low level of oxygen in the tissues.

Normal Adult PaO2

A normal arterial blood gas value of between $80$ and $100\,\text{mmHg}$ in an adult.

Normal Adult SpO2

A normal blood oxygen saturation of $95\text{ to }99\%$ while breathing room air.

Cor Pulmonale

Right-sided heart failure caused by increased workload on the right side of the heart as a result of hypoxemia-induced pulmonary vasoconstriction and pulmonary hypertension.

Tachycardia

An abnormally fast heart rate, which can be an objective clinical sign of hypoxemia.

Tachypnea

An abnormally fast respiratory rate, which can serve as a compensatory mechanism or sign of hypoxemia.

Hyperoxic Acute Lung Injury

Oxygen toxicity defined as a $\text{PaO}_2$ greater than $300\,\text{mmHg}$ (with a warning threshold above $150\,\text{mmHg}$), which causes vasoconstriction, decreased cardiac output, reduced vital organ perfusion, and lower lung infiltrates resembling bronchopneumonia.

Hypercapnia

Chronically elevated levels of carbon dioxide in the blood ($\text{PaCO}_2$), frequently present in patients with chronic obstructive pulmonary disease (COPD).

Depression of Ventilation

A potential hazard occurring in a small subpopulation of COPD patients with chronic hypercapnia whose breathing drive relies on hypoxic drive; administering excessive oxygen eliminates this drive, causing hypoventilation and reduced respiratory rate.

Retinopathy of Prematurity

An abnormal ocular condition in premature, low-birth-weight infants where elevated $\text{PaO}_2$ causes retinal vasoconstriction, vessel necrosis, excessive new vessel formation, hemorrhage, scarring, and possible retinal detachment or blindness.

Absorption Atelectasis

The collapse of alveoli occurring when shallow-breathing patients with low tidal volumes receive high concentrations of oxygen ($50\%$ or greater), rapidly depleting nitrogen from the blood and lung sacs.

Fixed FiO2 Device

An oxygen delivery system that supplies all of the patient's inspired gas, ensuring that the delivered fraction of inspired oxygen is guaranteed regardless of the patient's breathing pattern.

Variable FiO2 Device

An oxygen delivery system that provides only a portion of the patient's inspired gas, requiring the patient to entrain room air to meet inspiratory demand, which dilutes the delivered oxygen concentration.

Low Flow System

An oxygen delivery design that delivers gas at flow rates of $8\,\text{L/min}$ or less with variable $\text{FiO}_2$, requiring ambient air entrainment to satisfy adult flow needs.

Reservoir System

A variable $\text{FiO}_2$ delivery design that stores and gathers oxygen between breaths, enabling the patient to draw from the stored oxygen reservoir rather than surrounding room air during peak flow.

High Flow System

A fixed $\text{FiO}_2$ oxygen delivery system capable of meeting or exceeding the patient's total inspiratory flow demand, guaranteeing the exact concentration of oxygen administered.

Rule of Fours

A clinical rule of thumb for low flow nasal systems stating that for each $1\,\text{L/min}$ increase in oxygen flow, the $\text{FiO}_2$ increases by approximately $4\%$, starting at $24\%$ for $1\,\text{L/min}$.

Nasal Cannula

A low flow delivery device featuring two prongs inserted into the nares, delivering an $\text{FiO}_2$ of $22\text{ to }40\%$ (up to $44\%$) at flow rates ranging from $\frac{1}{4}\text{ to }6\,\text{L/min}$.

Nasal Catheter

A low flow oxygen delivery device positioned above the uvula and switched between nares every $8\,\text{hours}$, delivering an $\text{FiO}_2$ of $22\text{ to }45\%$ at flows of $\frac{1}{4}\text{ to }5\,\text{L/min}$ for short-term procedures such as bronchoscopy.

Transtracheal Catheter

A surgical low flow oxygen device placed between the second and third tracheal rings, delivering an $\text{FiO}_2$ of $22\text{ to }35\%$ at flows of $\frac{1}{4}\text{ to }4\,\text{L/min}$, requiring $40\text{ to }60\%$ less oxygen flow than a standard nasal cannula.