Environmental Flashcards
It has been reported that approx 73% of humans with smoke inhalation injury experience respiratory failure and __% will progress to ARDS
20%
What is a major contributor to the pathophysiology of smoke inhalation?
Inspiration of superheated particulate matter (soot)
Why is inhalation of soot such a big deal?
1 - direct heat damage
2 - particles and be contaminated with toxins that get transported to the alveoli
The major result of upper airway injury during fires?
Edema and inflammation leading to airway obstruction
When does the peak of airway edema occur post fire/smoke inhalation?
24 hours
During smoke inhalation, what causes the majority of lower airway injury?
Chemical irritation
What is the series of events that occur after inhalation of smoke in the lower airways?
1 - production of neutropeptides
2 - activation of vagal nerve sensory fibers containing pro inflammatory peptides, neurokinins and calcitonin gene-related peptide
3 - severe inflammatory response
4 - sequelae include bronchconstriction, pulmonary vasoconstriction, fluid accumulation
Name for the degenerated epithelial cells, mucus and fluid in the airways after smoke inhalation
Airway casts
What is released during smoke inhalation in the lower airways that worsens VQ mismatch
NO
What are the two phases of lower airway injury after smoke inhalation? When does bronchopneumonia occur? Why?
Hyperactive phase
Prolonged recovery phase
Pneumonia develops in the recovery phase due to disrupted bronchial epithelium and impaired innate immune system
What are changes that occur in lung parenchyma after smoke inhalation
Increased fluid flux
Lack of surfactant
Loss of hypoxic pulmonary vasoconstriction (more NO)
Atelectasis
Fibrin deposition (procoagulant)
What are systemic effects of smoke inhalation?
Ocular - direct corneal damage, ulceration
Cardiac - LV dysfunction (direct injury or RV hypertension)
Pulmonary - hypoxemia, hypercapnia
What is considered a risk factor for the development of hypercoagulability on people?
CO inhalation
What are the two most toxic compounds present in smoke
CO
HC
What is CO’s affinity for Hb compared to oxygen?
200-250 x
CO has what effect on the oxyhemoglobin dissociation curve?
Left (oxygen is LOCKED on, less to tissue)
What are the “other” mechanisms of CO intracellular toxicity?
Inhibition of cytochrome oxidase enzyme (cells can’t use oxygen)
Inhibition of cytochrome c-oxidase (electron chain dysfunction, superoxide production, mitochondrial stress)
Primary toxic effect of HC?
Inhibits electron transport chain impairing ATP production
What neurologic syndrome occurs after smoke inhalation? When can it occur? What is the cause?
Delayed neurologic syndrome (DNS)
10 hours - 6 days
CO
Hyperlactatemia in a patient with adequate perfusion parameters with a history of being in a house fire ahould raise suspicion for…
Carbon monoxide intoxication
What is the half life of CO at room air
320 min
What is the half life of CO at FiO2 of 1?
70 min
What are considerations to make when choosing what method of oxygen to use in a smoke inhalation patient?
Burns on/around the nose preventing cannula placement
Excessive exudate
Upper airway obstruction (temp trach)
Neuro hypercapnia/ bad enough lower airway disease (MV)
Other than oxygen, what is the major focus for managing smoke inhalation patients?
Clearing airway secretions
Methods to clear airway secretions (smoke inhalation)
Early ambulation
Chest physical therapy
Airway suctioning
What are aerosolized medications that can be used for smoke inhalation patients? List each’s benefit
Albuterol - bronchodilation, anti-inflammatory, promote alveolar fluid clearance
Epinephrine - bronchodilator, vasoconstriction, break up secretions
NAC - mucolytic (BUT can cause bronchconstriction)
Heparin - reduce airway fibrin casts, paper showed reduced mortality with use
A recent meta-analysis of human patients with inhalation injury concluded that what nebulized drug was associated with reduced mortality, improved lung function, and shortened the period of MV?
Nebulized heparin
What are the antidotes for HC toxicity? Which is safer and why?
Amyl nitrate and sodium thiosulfate
Hydroxycobalamin
Hydroxycobalamin because it binds cyanide to form cyanocobalamin (not methemoglobinemia)
