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Inhalation Injury

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Inhalation Injury Powered By Docstoc
					Inhalation Injury
       Arek Wiktor M.D.
           Burn Fellow
 University of Colorado Hospital
                     Outline
   Background
   Smoke
   Pathophysiology
   Diagnosis
   Treatment
   Specific Lethal Compounds



               http://spanishlakefd.com/firealarms/
           Learning Objectives
   Describe the pathophysiology of inhalation
    injury
   How is inhalation injury diagnosed?
   What adjunctive measures are used to treat
    inhalation injury?
   What is the treatment for carbon monoxide and
    cyanide poisoning?
A Sunday afternoon stroll thru the fire…




http://www.aeromedix.com/product-exec/parent_id/1/category_id/12/product_id/1074/nm/Safe_Escape_Smoke_Hood
              Epidemiology

   15-30% of burn admissions have inhalation
    injury
   Independent predictor of mortality, ↑ by 20%
   Increases pneumonia risk
   Leading diagnosis of those hospitalized and
    treated on 9/11, World Trade Center attack
       Anatomic Classification


 Upper airway
 Lower airway

 Systemic toxicity




            http://www.monroecc.edu/depts/pstc/backup/parasan4.htm
                         SMOKE
   Variable, changes with time burning
   Toxic gases and low ambient oxygen
   Ingredients:
         Aldehydes (formaldehyde, acrolein), ammonia,
         hydrogen sulfide, sulfur dioxide, hydrogen chloride,
         hydrogen fluoride, phosgene, nitrogen dioxide, organic
         nitriles
   Particulate matter


                     Prien et al. Burns 1988; 14:451-460
               Pathophysiology
   Cilia loss, respiratory epithelial sloughing
   Neutrophilic infiltration
   Atelectasis, occlusion by debris/edema
   Pseudomembranes
   Bacterial colonization at 72 hrs




                   Hubbard et al. J Trauma 1991; 31:1477-1486
Bartley et al. Drug Design, Development and
Therapy. 2008; 2: 9–16.
         Secondary Lung Injury
   Unilateral smoke inhalation damages
    contralateral lung
   Immune response, increased permeability
   Oxygen-derived free radicals
   NO mediated damage (chemotactic factor neuts)
   Eiscosanoids (TXA2→TXB2)
   Reduced phagocytosis in macrophages
              Systemic Effects

   Larger fluid resuscitation (2→5cc/kg/%)
   Additive effect to burns
   12% pts inhalation injury alone require
    intubation*
   62% pts burn + inhalation injury intubated*




              Clark et al. J Burn Care Rehabilitation, 1990; 11:121-134
Miller et al. Journal of Burn Care Research. 2009; 30(2) 249-256
                          Diagnosis
   Clinical findings:
       Facial burns (96%)
       Wheezing (47%)
       Carbonaceous sputum (39%)
       Rales (35%)
       Dyspnea (27%)
       Hoarsness (26%)
       Tachypnea (26%)
       Cough (26%)
       Cough and hypersecretion (26%)

                   DiVincenti et al. Journal of Trauma, 1971; 11:109-117
  NO ONE FINDING IS
SUFFICIENTLY SENSITIVE
      OR SPECIFIC!


Must use clinical judgment!
           Tools for Diagnosis

   Bronchoscopy
   Pulmonary function testing
   Xenon133 lung scan
Grades of Inhalation Injury




   Endorf and Gamelli. Journal of Burn Care and Research. 2007; 28:80-83
              Treatments
   Airway Control
   Chest physiotherapy
   Suctioning
   Therapeutic bronchoscopy
   Ventilatory strategies
   Pharmacologic adjuncts
                       Treatment
Control the Airway!!!
   ≥ 40% burn
   Transport




       http://www.burnsurgery.com/Betaweb/Modules/initial/bsinitialsec2.htm
          Ventilator Strategies
   Airway pressure release ventilation (APRV)
   Intrapulmonary percussive ventilation (IPV)
   High-frequency percussive ventilation (HFPV)
   High frequency oscillatory ventilation (HFOV)
   Single center, prospective randomized trial 2006-2009
   387 pts screened
   31 pts HFPV, 31 pts LTV (ARDSnet)




                  Chung et al. CCM; 2010: 38(10) 1970-1977
                         Results
   No significant difference in mortality or ventilator free
    days
   Significant difference in “Rescue Therapy”
                         Results
   No significant difference in mortality or ventilator free
    days
   Significant difference in “Rescue Therapy”
P/F ratio vs Ventilator Mode




       Chung et al. CCM; 2010: 38(10) 1970-1977
          Study Conclusions
 Study stopped for safety concerns in LTV group
 Gas exchange goals met in all HFPV pts, and
  not in 1/3 of LTV pts
 Trend for less barotrauma, less VAP, less
  sedation
“Strict application of LTV may be suboptimal
              in the burn population”
Pharmacologic Intervention




     Bartley et al. Drug Design, Development and Therapy. 2008; 2: 9–16.
Pharmacologic Intervention




     Bartley et al. Drug Design, Development and Therapy. 2008; 2: 9–16.
          Airway Obstructive Casts
   Mucus secretions
   Denuded airway epithelial cells
   Inflammatory cells
   Fibrin
       -Solidifies airway content
   Several studies shown reduction in size of casts
    with fibrinolytic agents (tPA)
      Casts




Enkhbaatar et al., 2007
Theory Behind Inhaled Heparin
   Animals with Burn + ARDS have decreased
    levels of antithrombin in plasma and BAL
    specimens
   Heparin potentiates antithrombin by 2000x
   Prevention of fibrin deposition in lungs
   Heparin inhibits antihrombin’s anti-
    inflammatory effect - ? systemic rhAT ?
        Shriners Protocol
Since 1990 (560+ patients treated)




          Mlcak RP et al. Burns, 2007;33:2-13
                  Evidence (Pro)
   Desai et al. 1998
       Pediatric burns (90 pts total)
       1985-1989 (43) vs 1990-1994 (47pts)
       ↓ reintubation, atelectasis, and mortality
   Miller et al. 2009
       30 patients over 5 years, retrospective review
       Tx 10,000 units heparin, 20% NA, 0.5 ml AS q4 hrs
       Survival benefit, improved LIS scores, compliance
       Number needed to treat 2.73
              Evidence (Con)
 Holt et al. 2008
      Retrospective review 1999-2005, 150 pts total
      Burn size, LOS, time on vent, mortality SAME
      Only 68% pts had bronchoscopy,
      Attending discretion which treatment to use
TOXIC GASES
       Carbon Monoxide (CO)

   CO from incomplete combustion
   CO + Hb → COHb (affinity 200-250x)
   LEFT shift of oxy-Hb curve (Haldane effect)
   CO binding to intracellular cytochromes and
    metalloproteins (myoglobin)
   “Two compartment” pharmacokinetics
          Animal experiment 64% COHb transfusion
          CO Toxicity Symptoms

   “Cherry-red lips, cyanosis, retinal hemorrhage”- rare
   CNS and Cardiovascular
       ↑ RR, ↑HR, dysrhythmias, MI, ↓BP, coma, seizures
   Delayed neuropsychiatric syndrome (3-240d)
     Cognitive/personality changes/parkinsonianism
     Spontaneous resolution
Signs and Symptoms




    Weaver LK. N Engl J Med 2009;360:1217-25.
             CO Toxicity Diagnosis
   Pulse oximetry false                COHb Symptoms
    HIGH SpO2                            %
   Need cooximetry direct               0-5    Normal

    measurement of COHb                 15-20   Headache, confusion,
       Older ABG analyzers (estimate           fatigue
        off dissolved PO2)              20-40   Hallucination, vision
                                                Δ’s
   MRI – lesions globus
                                        40-60   Combative, coma
    pallidus/basal
    ganglia/deep white                  60 +    Cardiopulmonary
    matter                                      arrest
             CO Toxicity Diagnosis
   Pulse oximetry false                COHb Symptoms
    HIGH SpO2                            %
   Need cooximetry direct               0-5    Normal

    measurement of COHb                 15-20   Headache, confusion,
       Older ABG analyzers (estimate           fatigue
        off dissolved PO2)              20-40   Hallucination, vision
                                                Δ’s
   MRI – lesions globus
                                        40-60   Combative, coma
    pallidus/basal
    ganglia/deep white                  60 +    Cardiopulmonary
    matter                                      arrest
             CO Toxicity Treatment
   OXYGEN
   Half-life COHb (min)

               RA     100%   100% O2
              1ATM     O2    2.5 ATM
      Male    240      47       22

     Female   168      33       15


   Carbogen – normobaric, normocapnic, hyperventilation (4.5-
    4.8% CO2)
   Hyperbaric oxygen???
                 Cyanide (CN)
   Combustion of synthetics (plastics, foam, varnish,
    paints, wool, silk)
   Binds to cytochrome c oxidase – dose dependent
   Uncouple mitochondria
   Aerobic → anaerobic = Lactic acid
   Half-life 1-3 hours
         CN Toxicity Symptoms
   Dyspnea
   Tachypnea
   Vomiting
   Bradycardia
   Hypotension
   Giddiness/Coma/Siezures
   Death
* The smell of bitter almonds on the breath suggests exposure
   (cannot be detected by 60% of the population)
      CN Toxicity Diagnosis
 No rapid assay
 High lactate (>10mmol/L) (s/s, 87%/94%)

 Metabolic acidosis

 Elevated mixed venous saturation (<10% a-v)
  difference
 High index of suspicion

** Also get: COHb and Methemoglobin levels
               CN Treatment

 Cyanokit (Hydroxocobalamin)
 70mg/kg  dose (5g vials)
 Combines with cyanide to from cyanocobalamin (Vit B12)

 Red membranes/urine

 Hypertension, Anaphylaxis

 5% increase COHb, interfere with HD
  LFTs/Cr/Fe levels
         Cyanide Antidote Kit (CAK)
     Amyl nitrite pearls, sodium nitrite, and sodium thiosulfate

   Amyl nitrate and sodium nitrate induce methemoglobin
   Methemoglobin+cyanide→releases cyanide from CC
   Sodium thiosulfate enhances cyandide→thiocynate→renal
    excretion
   Avoid nitrate portion in pts with inhalation injury
    (COHb >10%)
   Vasodilation and hypotension
    Acquired Methemolgobinemia
   NO2, NO, benzene gases → oxidation of iron
   Fe2+ → Fe3+
   Shift curve to LEFT
   Blood “Chocolate brown color”
   Normal PaO2, pulse ox >85%
   Tx: Methylene blue (1-2 mg/kg Q 30-60min)
               Final Thoughts
   Inhalation injury is bad
   Support the airway
   Frequent bronchoscopy and monitoring
   Different ventilatory strategies
   Adjunctive measures need further investigation
The Toilet Snorkel




  http://www.icbe.org/2006/01/18/the-toilet-snorkel/
Thank You!
           Learning Objectives
   Describe the pathophysiology of inhalation
    injury
   How is inhalation injury diagnosed?
   What adjunctive measures are used to treat
    inhalation injury?
   What is the treatment for carbon monoxide and
    cyanide poisoning?

				
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