Learn: RES Equipment Wk 4 (extensive)

What is oxygen therapy?

Oxygen therapy is the administration of oxygen at concentrations greater than those found in ambient air.

What is an important principle to remember about oxygen?

O₂ is considered a drug.

Why is oxygen considered a drug?

Oxygen is used for diagnosis, treatment, mitigation, or prevention of disease/disorder or abnormal physical states and their symptoms.

How is oxygen regulated in Canada according to the slides?

Health Canada authorized oxygen as a drug and issued it an 8-digit Drug Identification Number (DIN).

What is the general goal of oxygen therapy?

To treat or prevent hypoxemia, thereby preventing tissue hypoxia that may result in tissue injury or cell death.

What is hypoxemia?

Low oxygen in the blood.

What is hypoxia?

Low oxygen in the tissues.

Can a patient have hypoxia without hypoxemia?

Yes. Hypoxemia can lead to hypoxia, but hypoxia can also occur without hypoxemia.

What is the difference between hypoxemia and hypoxia?

Hypoxemia is low oxygen in the blood; hypoxia is low oxygen in the tissues.

What analogy does the instructor use for hypoxemia versus hypoxia?

Blood is like the car and oxygen is the gas; hypoxia is like having enough gas but a flat or missing tire.

What is another overall goal of oxygen therapy?

Maintain adequate oxygen levels in the body without adversely affecting the heart and lungs.

What is the oxygen therapy goal regarding cardiopulmonary work?

Maintain adequate tissue oxygenation while minimizing cardiopulmonary work.

What are three specific goals of oxygen therapy?

1) Correct acute hypoxemia; 2) decrease symptoms associated with chronic hypoxemia; 3) decrease the workload hypoxemia imposes on the cardiopulmonary system.

What are three ways to determine whether a patient requires oxygen?

Clinical presentation, diagnosis/pathophysiology, and laboratory/equipment measurements.

What three areas of clinical presentation are assessed when determining oxygen need?

Respiratory, cardiovascular, and neurologic findings.

What types of diagnoses may suggest a need for oxygen therapy?

Cardiorespiratory diseases such as COPD, lung cancer, CHF, and ILD.

Can oxygen requirements change during a disease process?

Yes. Oxygen needs may change at different stages of disease.

What respiratory sign can indicate hypoxia?

Tachypnea.

What does tachypnea mean?

Quick or rapid breathing.

What respiratory sign can indicate hypoxia and may be assessed by observing work of breathing?

Dyspnea.

What does dyspnea mean?

Shortness of breath.

What does increasing work of breathing suggest according to the instructor?

More severe respiratory difficulty/work.

What skin-color changes can occur with hypoxia?

Paleness and cyanosis.

How does cyanosis progress according to the instructor notes?

It may begin at the extremities and progress toward the core as the condition becomes severe.

What cardiovascular response may occur with hypoxia early on?

Tachycardia.

What can severe/prolonged hypoxia do to heart rate?

It can progress to bradycardia as oxygen levels become very low and cellular injury/death occurs.

What cardiac rhythm abnormality can occur with severe hypoxia?

Arrhythmia.

What blood-pressure change can occur with hypoxia?

Hypertension may occur, with vasoconstriction noted in the instructor material.

What can severe hypoxia eventually do to blood pressure?

It can lead to hypotension associated with cellular injury/death.

What does lassitude mean?

Fatigue.

What does severe somnolence mean?

A very sleepy state.

Why should a patient saying they feel like they are going to die not be ignored?

The instructor identifies this as a severe symptom/side effect requiring attention.

What is coma?

A state of lack of responsiveness, even to an external stimulus such as a chest rub.

What may need to be considered when a hypoxic patient progresses to coma?

Intubation or ventilation.

What is the intervention focus when signs suggest hypoxemia or hypoxia?

Alleviating the hypoxemia or hypoxia.

How can diagnosis help determine oxygen need?

The pathophysiology of the patient's cardiorespiratory disease can suggest a need for oxygen therapy.

What laboratory measurement directly measures dissolved oxygen in arterial blood?

PaO₂.

What does PaO₂ represent?

The amount of dissolved oxygen in arterial blood.

How is PaO₂ obtained?

By obtaining an arterial blood sample.

What does SaO₂ represent?

Arterial oxygen saturation of hemoglobin.

How is SaO₂ obtained according to the slides?

It is determined/calculated from arterial blood information including PaO₂.

What does SpO₂ represent?

Peripheral oxygen saturation of hemoglobin measured using pulse oximetry.

What is the difference between PaO₂, SaO₂, and SpO₂?

PaO₂ measures dissolved oxygen in arterial blood; SaO₂ represents arterial hemoglobin saturation; SpO₂ estimates peripheral hemoglobin saturation using pulse oximetry.

Which measurement is obtained invasively from an arterial blood sample?

PaO₂.

Which measurement is obtained using pulse oximetry?

SpO₂.

What is the normal PaO₂ range listed in the slides?

80-100 mmHg.

What PaO₂ indicates mild hypoxemia according to the slides?

60-79 mmHg.

What PaO₂ indicates moderate hypoxemia?

40-59 mmHg.

What PaO₂ indicates severe hypoxemia?

Less than 40 mmHg.

What PaO₂ corresponds approximately to an SaO₂ of 90% under normal conditions?

Approximately 60 mmHg.

How should SpO₂ compare with SaO₂?

SpO₂ should approximate SaO₂.

What saturation target is listed for most patients?

SpO₂/SaO₂ greater than approximately 90-92%.

A patient has a PaO₂ of 55 mmHg. How is the hypoxemia classified according to the slides?

Moderate hypoxemia.

A patient has a PaO₂ of 35 mmHg. How is the hypoxemia classified?

Severe hypoxemia.

A patient has a PaO₂ of 70 mmHg. How is the hypoxemia classified?

Mild hypoxemia.

What is a documented indication for oxygen therapy?

Documented hypoxemia, such as low PaO₂ or SpO₂.

Can oxygen be indicated when hypoxemia is suspected but not yet documented?

Yes. An acute situation in which hypoxemia is suspected is listed as an indication.

What type of trauma can indicate oxygen therapy?

Severe trauma.

When may oxygen be used for short-term therapy?

During or around surgical/interventional procedures as indicated.

Why may oxygen be used during conscious sedation procedures according to the instructor?

To support the patient during procedures such as treatment of fractures while sedation is used.

Why may oxygen be indicated after severe trauma?

Trauma can involve major blood loss and decreased hemoglobin, contributing to inadequate oxygen delivery.

What is listed as a contraindication to oxygen therapy?

Patient refusal.

What is another type of contraindication/application problem?

Situational equipment issues where a particular interface is inappropriate for the patient.

What example of a situational equipment issue is given?

A nasal cannula may be inappropriate for a neonate because its size can obstruct the airway.

Is oxygen therapy generally well tolerated?

Yes, according to the slides, and it reverses hypoxemia or hypoxia.

What are the five major hazards of oxygen therapy covered in the slides?

Oxygen toxicity/oxidative stress, depression of ventilation, retinopathy of prematurity, absorption atelectasis, and fire hazards.

What two factors determine the harmful effects of oxygen toxicity?

PaO₂ and exposure time.

How does increasing PaO₂ affect oxygen toxicity risk?

Higher PaO₂ increases the likelihood of oxygen-related damage.

How does increasing exposure time affect oxygen toxicity risk?

Longer exposure increases the likelihood of oxygen-related damage.

What organs are affected by oxygen toxicity?

The lungs and central nervous system.

At what pressures do pulmonary oxygen toxicity effects occur?

At atmospheric pressure or greater.

At what pressures do CNS oxygen toxicity effects occur?

At pressures greater than 1 atmosphere, such as hyperbaric conditions.

What causes oxygen toxicity at the cellular level?

Overproduction of oxygen free radicals that can overwhelm normal antioxidant defenses.

What happens when free radicals overwhelm antioxidant defenses?

Cell damage occurs.

How can oxygen toxicity create a continuing cycle of injury?

Cell damage triggers an immune response that releases more free radicals, causing further damage.

What happens to blood oxygenation as lung injury from oxygen toxicity worsens?

Blood oxygenation can worsen.

What structure is damaged by high PO₂ during oxygen toxicity?

The capillary endothelium.

What can happen to the membrane oxygen must cross during lung injury?

The membrane can thicken, making oxygen transfer more difficult.

What is the instructor's warning about treating progressive hypoxemia with additional oxygen?

If progressive hypoxemia is managed with additional oxygen, toxic effects can worsen.

What is the general strategy for minimizing oxygen toxicity?

Use the lowest possible FiO₂ that achieves adequate tissue oxygenation.

What percentage oxygen can adults breathe for extended periods according to the slides without major lung damage?

Up to approximately 50%.

How long should exposure to 100% oxygen be limited whenever possible?

Less than 24 hours.

What FiO₂ should be attempted within 2 days according to the slides?

Decrease to approximately 70%.

What FiO₂ should be attempted within 5 days according to the slides?

50% or less.

What can happen to pulmonary damage if FiO₂ can be decreased while keeping the patient alive?

Pulmonary damage may resolve.

Why are neonates particularly susceptible to oxygen toxicity?

Growing lungs are more sensitive to oxygen and high PO₂.

What is the key oxygen-toxicity principle emphasized by the instructor?

Harmful effects are related to high PaO₂ rather than simply high FiO₂.

Should supplemental oxygen be withheld from a hypoxemic patient because of concern about oxygen toxicity?

No. The slides emphasize that supplemental oxygen should not be withheld from hypoxemic patients.

What is the overall balance when administering oxygen?

Provide enough oxygen to achieve adequate tissue oxygenation while using the lowest effective FiO₂.

What is the second major hazard of oxygen therapy?

Depression of ventilation.

Which patients may hypoventilate when exposed to moderate-to-high oxygen concentrations?

A small percentage of patients with COPD.

What is the mechanism described for oxygen-induced depression of ventilation in susceptible COPD patients?

High oxygen levels can satisfy chemoreceptors, reducing the hypoxic stimulus to breathe in patients who rely more heavily on hypoxic drive.

What happens to the normal response to elevated PaCO₂ in these susceptible patients?

The normal response to elevated PaCO₂ may be blunted.

What is hypoxic drive?

A stimulus to breathe associated with low blood oxygen levels.

How can high blood oxygen affect a patient relying on hypoxic drive?

It can satisfy the chemoreceptor stimulus and reduce the drive to breathe.

What can result from oxygen-induced depression of ventilation?

Hypoventilation and worsening hypercapnia.

What PaCO₂ range is described as normal in the instructor notes?

Approximately 35-45 mmHg.

What PaCO₂ values may be seen in the chronically hypercapnic patients described in the notes?

Values in the 60s-70s and sometimes up to 100 mmHg.

What is the key caution regarding oxygen administration in susceptible COPD patients?

Monitor the patient's response rather than assuming oxygen should be withheld.

What is retinopathy of prematurity?

A condition in premature infants associated with high PaO₂ that can damage retinal blood vessels.