Inhalation Injury Flashcards
What two toxins are commonly associated with inhalation injuries?
Carbon monoxide (CO) and Cyanide (CN).
What is carbon monoxide poisoning?
A condition caused by CO binding to hemoglobin, impairing oxygen delivery and causing tissue hypoxia.
Why does carbon monoxide poisoning cause a normal pulse oximetry reading?
CO binds to hemoglobin with high affinity, preventing oxygen unloading but still allowing pulse oximetry to detect bound hemoglobin, falsely appearing normal (92-100%).
What are the major sources of carbon monoxide exposure?
- Smoke inhalation
- Fuel-burning devices in enclosed spaces
- Malfunctioning furnaces
- Car exhaust fumes
What is the classic presentation of mild CO poisoning?
Headache, dizziness, nausea, malaise, and confusion, with normal pulse oximetry readings.
What are severe symptoms of CO poisoning?
Altered mental status, seizure, coma, cardiac ischemia, and respiratory failure.
What laboratory test is used to diagnose carbon monoxide poisoning?
ABG with co-oximetry, which shows elevated carboxyhemoglobin levels (>15% in smokers, >3% in nonsmokers).
How does CO poisoning affect the hemoglobin-oxygen dissociation curve?
Causes a left shift, reducing oxygen release to tissues (cause hemoglobin to behave like myoglobin).
What is the treatment for carbon monoxide poisoning?
100% oxygen via non-rebreather mask; hyperbaric oxygen therapy if severe (neurologic symptoms, pregnancy, or high carboxyhemoglobin levels).
What is cyanide poisoning?
A toxic condition where cyanide inhibits cytochrome C oxidase in the electron transport chain, preventing ATP production and leading to metabolic acidosis.
What are the major sources of cyanide exposure?
House fires (burning plastic, wool, silk), industrial exposure, and nitroprusside overdose.
What is the classic clinical presentation of cyanide poisoning?
Headache, confusion, seizure, bradycardia, hypotension, arrhythmia, and lactic acidosis (>10 mmol/L).
Why does cyanide poisoning cause bright red skin and blood?
Cyanide prevents oxygen utilization, leading to high arterial oxygen content and bright red venous blood.
Why is cyanosis typically absent in cyanide poisoning?
Because oxygen remains bound to hemoglobin due to impaired tissue oxygen utilization.
How is cyanide poisoning diagnosed?
Clinical suspicion + severe lactic acidosis. No rapid confirmatory test is available.
What is the first-line treatment for cyanide poisoning?
Hydroxycobalamin (binds cyanide to form cyanocobalamin, which is renally excreted), which is a form of vitamin B12.
What alternative treatments exist for cyanide poisoning?
- Sodium thiosulfate (converts cyanide to thiocyanate for renal excretion)
- Nitrites (induce methemoglobinemia to bind cyanide, used in severe cases)
Which poisoning is more commonly associated with cherry red skin?
Carbon monoxide poisoning, though cyanide poisoning can also cause bright red skin due to increased arterial oxygen content.
How do CO and cyanide poisoning differ in oxygen saturation and utilization?
CO poisoning impairs oxygen delivery (left shift), while cyanide poisoning impairs utilization (inhibits oxidative phosphorylation).
What are the three major components of inhalation injury?
- Upper airway thermal injury (supraglottic burns, edema)
- Lower airway chemical injury (bronchospasm, inflammation)
- Systemic toxicity (CO, cyanide poisoning).
What are clinical signs of inhalation injury?
Singed nasal hairs, facial burns, carbonaceous sputum, hoarseness, wheezing, respiratory distress.
What is the immediate management for suspected inhalation injury?
100% oxygen to displace CO and reduce systemic toxicity.
When should you consider early intubation in inhalation injury?
If there are signs of airway edema (oropharyngeal blistering, hoarseness, stridor, or hypoxia).
What is the role of fiberoptic laryngoscopy in inhalation injury?
Used in stable patients to assess airway edema and determine the need for intubation.
Why is noninvasive ventilation (e.g., BiPAP) discouraged in facial burns?
Because the tight-fitting mask can cause pain and worsen skin damage.
What is the major long-term pulmonary risk in burn patients?
Acute respiratory distress syndrome (ARDS), often exacerbated by oxygen toxicity.
What is the best initial test for carbon monoxide poisoning?
ABG with co-oximetry to detect carboxyhemoglobin levels.
What is the best initial test for cyanide poisoning?
Clinical diagnosis based on exposure history and severe lactic acidosis.
What is the most common cause of death in burn victims?
Inhalation injury leading to airway obstruction and respiratory failure.
Why should patients with CO poisoning be monitored for at least 4 hours?
Because delayed neurologic sequelae can develop, including cognitive impairment and movement disorders.
What is the threshold for hyperbaric oxygen therapy in CO poisoning?
Severe cases with altered mental status, pregnancy, or carboxyhemoglobin levels >25%.
What are two key metabolic findings in cyanide poisoning?
Severe lactic acidosis (>10 mmol/L) and normal arterial oxygen content with bright red blood.
Which poisoning causes a left shift of the hemoglobin-oxygen dissociation curve?
Carbon monoxide poisoning.
Which poisoning results in high venous oxygen saturation?
Cyanide poisoning, due to impaired oxygen utilization by tissues.
Burn victims who suffer inhalation in injuries are an increase of developing what complication?
ARDS.
