Oxygen Therapy Flashcards
Oxygen Therapy and Ventilation Demands
Patients with hypoxemia that are breathing on room air can achieve acceptable arterial oxygenation through an increase in ventilation
However by increasing ventilation we are also increase work of breathing meaning that through the use of oxygen therapy we can decrease ventilation as well as work of breathing
Oxygen Therapy and Cardiac Output
Cardiac output increases to try and maintain oxygenation, so when we give oxygen the heart will not have to pump as blood per minute in order to meet tissue demands
This can be especially important when the heart is already stressed through disease or trauma
Oxygen Therapy and Pulmonary Vasoconstriction
Hypoxemia will cause pulmonary vasoconstriction and pulmonary hypertension both of which may increase the workload of the heart
This is why patient with chronic hypoxemia will increase the workload on right side of the heart leading to right ventricular failure (cor pulmonale)
O2 therapy can help to reverse pulmonary vasoconstriction and decrease right ventricular workload
Respiratory Symptoms With Severe Hypoxemia
Tachypnea
Dyspnea
Cyanosis
Respiratory Symptoms With Mild to Moderate Hypoxemia
Tachypnea
Dyspnea
Paleness
Cardiovascular Symptoms with Severe Hypoxemia
Tachycardia-Eventual Bradycardia and arrhythmia
Hypertension-Eventual hypotension
Cardiovascular Symptoms with Mild to Moderate Hypoxemia
Tachycardia
Mild Hypertension
Peripheral Vasoconstriction
Neurological Symptoms with Severe Hypoxemia
Somnolence
Confusion
Distressed Appearance
Blurred or Tunnel Vision
Loss of Coordination
Impaired Judgement
Slow Reaction Time
Manic Depression
Coma
Neurological Symptoms with Mild to Moderate Hypoxemia
Restlessness
Disorientation
Headaches
Lassitude
Hospital Indications for Oxygen Therapy
- PaO2 <60 mmHg
- O2 Sats <90%
- Acute situations
- Suspected hypoxemia
- Severe trauma
- MI
- Short term
- Post anesthesia
Community Indications for Oxygen Therapy
PaO2 <55 mmHg, O2 Sat <89% @ rest
PaO2 <60 mmHg, O2 Sat <90% if indications of Cor Pulmonale, Polycythemia (Hct >56), CHF.
Significant ambulatory hypoxemia
Ex. Nocturnal de-sat
In What Situation Will Oxygen Therapy Not Help
Severe anemia
Major right to left shunt
Severe hypo-ventilation
Major circulatory impairment
No pump
Congenital heart defects which results in venous admixture
Oxygen Toxicity
Prolonged exposure to high levels of FiO2 will lead to effects on the CNS and lungs
What are the two primary components of oxygen toxicity
PO2
Exposure time
The higher the concentration of oxygen and the longer the exposure time the higher the likelihood of injury
Cycle of oxygen toxicity
High FiO2 can be toxic to the lungs parenchyma which will result in physiological shunting which in turn worsen hypoxemia leading to the use of high FiO2
Storage of Medical Gases and Cylinder Characteristics
Cylinders are constructed of chrome molybdenum steel.
Gas cylinders are stored at high pressures; a full O2 cylinder contains 2200 psig pressure.
Cylinder Sizes
Cylinders are constructed in various sizes.
The most common sizes for O2 storage are the H cylinder and the E cylinder.
The H cylinder holds 244 cu ft (6900 L) of O2.
The E cylinder used for transport holds 22 cu ft (622 L) of O2.
How many L are in 1 cu ft
There are 28.3 L in 1 cu ft.
Valves on Cylinders
Valves on the cylinder allow attachment of regulators that release the gas at various flow rates.
Cylinder and regulator safety systems dictate that the valves be constructed to allow the connection of only one type of gas regulator.
For example, an O2regulator cannot be attached to a helium cylinder.
Cylinder M arkings.
Calculating how long cylinder contents will last
Minutes Remaining in Cylinder = (Cylinder Pressure x Cylinder Factor) / Flow Rate)
