Respiratory Arrest

Question 1

What is respiratory arrest?

Answer 1

“Complete cessation of breathing in patients with a pulse”

Respiratory arrest is caused by apnea (temoporary cessation of breathing) or respiratory dysfunction severe enough it will not sustain the body. Prolonged apnea refers to a patient who has stopped breathing for a long period of time. If the heart muscle contraction is intact, the condition is known as respiratory arrest. 

Question 2

Describe the aetiology behind respiratory arrest

Answer 2

1. Extrapulmonary → CNS depression (opioid intoxication), respiratory muscle weakness (myasthenia gravis, ALS), airway obstruction (aspiration), drowning, trauma
2. Pulmonary → airway obstruction (bronchospasm in asthma/COPD patients), impaired alveolar diffusion (pulmonary oedema, pneumonia)

Question 3

What are the risk factors for respiratory arrest?

Answer 3

• smoke tobacco products 
• drink alcohol excessively 
• have a family history of respiratory disease or conditions 
• sustain an injury to the spine, brain, or chest 
• have a compromised immune system 
• have chronic (long-term) respiratory problems, such as cancer of the lungs, chronic obstructive pulmonary disease (COPD), or asthma 

Question 4

What symptoms can be found on history that may suggest a pt at risk of respiratory arrest?

Answer 4

• Localized pulmonary findings reflecting the acute cause of hypoxemia (eg, pneumonia, pulmonary edema, asthma, or chronic obstructive pulmonary disease [COPD]), may be readily apparent
• In patients with ARDS, the manifestations may be remote from the thorax, such as abdominal pain or long-bone fracture.
• Neurologic manifestations include restlessness, anxiety, confusion, seizures, or coma. 

Question 5

What investigations are used to monitor and diagnose respiratory arrest?

Answer 5

1. ABG → reduced oxygen, increased carbon dioxide
2. Pulse Oximetry
3. Chest radiography is essential in the evaluation of respiratory failure because it frequently reveals the cause 

Question 6

How is respiratory failure managed, to avoid progression to resp arrest?

Answer 6

1. Intubation
2. Mechanical Ventilation

• The risks of oxygen therapy are oxygen toxicity and carbon dioxide narcosis (Carbon dioxide (CO2) narcosis is a condition that develops when excessive CO2 is present in the bloodstream, leading to a depressed level of consciousness.) Pulmonary oxygen toxicity rarely occurs when a fractional concentration of oxygen in inspired gas (FiO2) lower than 0.6 is used; therefore, an attempt to lower the inspired oxygen concentration to this level should be made in critically ill patients. 
• Carbon dioxide narcosis occasionally occurs when some patients with hypercapnia are given oxygen to breathe. Arterial carbon dioxide tension (PaCO2) increases sharply and progressively with severe respiratory acidosis, somnolence, and coma. 

Question 7

What complications may be associated with resp failure than is progressing towards resp arrest?

Answer 7

Acute respiratory failure is frequently fatal. Attempts to decrease mortality must include attention to pulmonary and extrapulmonary complications. Pulmonary complications include pulmonary emboli, barotrauma, fibrosis, and pneumonia. 

Question 8

Describe the prognosis of resp arrest

Answer 8

Regardless of the cause, respiratory arrest is a life-threatening situation that requires immediate management. When a patient goes into respiratory arrest, they are not getting oxygen to their vital organs and may suffer brain damage or cardiac arrest within minutes if not promptly treated. 

Question 9

Explain the pathophysiology behind resp arrest

Answer 9

Upper airway obstruction may occur in infants<3 months, who are usually nose breathers and thus may have upper airway obstruction secondary to nasal blockage. At all ages, loss of muscular tone with decreased consciousness may cause upper airway obstruction as the posterior portion of the tongue displaces into the oropharynx. Other causes of upper airway obstruction include blood, mucus, vomitus, or foreign body; spasm or edema of the vocal cords; and pharyngolaryngeal tracheal inflammation (eg,epiglottitis,croup), tumor, or trauma. Patients with congenital developmental disorders (eg,Down syndrome,laryngeal disorders,congenital jaw abnormalities) often have abnormal upper airways that are more easily obstructed. 

 

Lower airway obstructionmay result from aspiration, bronchospasm, airspace filling disorders (eg,pneumonia,pulmonary edema, pulmonary hemorrhage), or drowning. 

Question 10

What signs of resp arrest can be found on physical examination?

Answer 10

• Asterixis
• Tachycardia
• Cyanosis
• Dyspnea (SOB)
• Diaphoresis (excessive or abnormal sweating for no apparent reason)
• Both confusion and somnolence (drowsiness) may occur in respiratory failure.
• Myoclonus (udden, brief involuntary twitching or jerking) and seizures may occur with severe hypoxemia.
• Polycythemia (disorder of too many RBC’s) is a complication of long-standing hypoxemia. 
• Pulmonary hypertension frequently is present in chronic respiratory failure. Alveolar hypoxemia potentiated by hypercapnia causes pulmonary arteriolar constriction. If chronic, this is accompanied by hypertrophy and hyperplasia of the affected smooth muscles and narrowing of the pulmonary arterial bed. The increased pulmonary vascular resistance increases afterload of the right ventricle, which may induce right ventricular failure. This, in turn, causes enlargement of the liver and peripheral edema. The entire sequence is known as cor pulmonale.