Chest X-Rays & ABG

What is the most common medical test in the US?

Chest x-ray

What percentage of the thoracic width should the heart take up in a normal chest x-ray?

45-55%

Are gastric air bubbles normal?

Yup

Which method is preferred for chest x-rays, PA or AP?

PA

What position are PA chest x-rays taken in?

Standing or sitting

With what chest x-ray view (PA or AP) are the scapula NOT overlapping the lung fields?

PA

In which chest x-ray view are the clavicles foreshortened, AP or PA?

AP

Which chest x-ray view has cardiac magnification, PA or AP?

AP

With what chest x-ray view will you see funding air bubbles, PA or AP?

PA

In what position would a patient get a AP chest x-ray?

Supine

Define consolidation

A pathologic process that fills the alveoli with fluid, pus, blood, cells, or other substances that results in lobar, diffuse, or multifocal ill-defined oapcities

Define atelectasis

A collapse of part of a lung due to a decrease in the amount of air in the alveoli which will result in a volume loss and increased density

What does interstitial mean in regards to chest x-rays?

There’s an involvement of the supporting tissue of the lung parenchyma that results in fine or coarse reticular opacities or small nodules

Define air bronchogram

A tubular outline of an airway made visible on a x-ray due to the filling of the surrounding alveoli by fluid or inflammatory exudates

In what situations will you see an air bronchogram on a chest x-ray?

• Lung consolidation

• Pulmonary edema

• Pulmonary atelectasis/collapse

• Interstitial disease

What are some symptoms of atelectasis?

• Dyspnea

• Hyperventilation

• Chest discomfort

What are some common causes of atelectasis?

• Surgery

• Prolonged b ed rest

• Shallow breathings

• Respiratory condition that causes an overproduction of mucus (cystic fibrosis, pneumonia, bronchitis)

If someone has atelectasis, will their trachea deviate to the same or opposite side of the atelectasis?

Same side

If you see pneumothorax on a chest x-ray, will the trachea be deviated towards or away from the pneumothorax?

Away from

What can consolidation cause?

• Pneumonia

• Lung infections

• Pulmonary edema

• Inflammatory lung diseases

What are some signs of a hyperinflated lung?

• Flattened hemidiaphragms

  • Flat enough that you can see more than 10 ribs

• Hyperlucent lungs (aka real see through)

• Narrowed heart silhouette

Describe what pulmonary edema would look like on a chest x-ray

Ground glass or butterfly pattern

Describe what a lung mass would look like on a chest x-ray

Lesion that is white with sharp margins and a homogenous appearance

What would pneumothorax look like on a chest x-ray?

Lung space will appear more black

What would pleural effusion look like on a chest x-ray?

Homogenous increase in density over the lower lung fields (aka solid white over lower lungs)

When would fluoroscopy typically be used?

• When trying to ID foreign objects in the lungs

• When ya doing guided needle biopsies

What are some reasons for a patient to get a chest CT?

• Detect lung masses

• Help diagnosis lymph node involvement

Why would someone get a chest MRI?

• Look at soft structures of the mediastinum, great vessels, and/or lungs

Why would someone get a chest PET scan?

• Look at ventilation and perfusion relationships

• Look at oxygen concentration

What kind of medical test often doesn’t show up much in regards to the lungs?

Ultrasound

What is the point of a chest V/Q scan?

• Show the mismatch of ventilation (air) to blood flow

• Diagnose PE

What is the point of an arterial blood gas (ABG) draw?

Assess oxygenation, ventilation, and metabolic function

When obtaining an ABG, what artery do they take a sample from?

Radial artery

What values are looked at for an ABG?

• pH

• PaO2

• PaCO2

• HCO3- (bicarbonate)

What is a normal pH range?

7.35 - 7.45

What is a normal PaO2 range?

80 - 100 mmHg

What is a normal PaCO2 range?

35 - 45 mmHg

What is a normal HCO3- range?

22 - 26 mEq

What kind of relationship does pH and PaCO2 have in the lungs?

Inverse relationship

What kind of relationship does pH and HCO3- have in the kidneys?

Direct relationship

When someone has respiratory acidosis, is there pH high or low? What about their PaCO2?

• pH low

• PaCO2 high

What are some causes of respiratory acidosis?

• Respiratory suppression from pharmacological, mechanical, and musculoskeletal causes

• Impaired perfusion caused by a MI, CHF, RV failure, or an arrhythmia

• Impaired ventilation caused by pneumonia, bronchospasm, pneumothorax

• Impaired diffusion caused by pulmonary edema or interstitial pneumonitis

If someone has metabolic acidosis, is pH high or low? What about HCO3-?

• pH is low

• HCO3- is low

What are some causes of metabolic acidosis?

• Renal failure

• Kektoacidosis

• Starvation

• Alcoholism

• Lactic acidosis from circulatory failure, respiratory failure, shock, drugs, or anemia

If someone has respiratory alkalosis, is their pH high or low? What about their PaCO2?

• pH high

• PaCO2 low

What are some causes of respiratory alkalosis?

• Anxiety

• Hyperventilation

• Midbrain lesions

• Fever

If someone has metabolic alkalosis, is their pH high or low? What about their HCO3-?

• pH high

• HCO3- high

What are some causes of metabolic alkalosis?

• Chloride depletion

• Severe potassium depletion

• Cushing’s syndrome

What PaO2 levels would be considered mild hypoxemia?

70-80 mmHg

What PaO2 levels would be considered moderated hypoxemia?

60-69 mmHg

What PaO2 levels would be considered severe hypoxemia and require a vent?

Anything under 60 mmHg

If a patient has primary respiratory acidosis, what would the compensatory process be?

Metabolic alkalosis

If a patient has primary respiratory alkalosis, what would the compensatory process be?

Metabolic acidosis

If a patient has primary metabolic acidosis, what would the compensatory process be?

Respiratory alkalosis

If a patient has primary metabolic alkalosis, what would the compensatory process be?

Respiratory acidosis