Inhalational Or Chemical ExposureAPPROACH

TOXICOLOGY AND BEHAVIORAL · 19 SECTIONS

⚲

543 items

☷ Legend

⚲

Resuscitation and Universal Approaches9▾

Chest and Cardiovascular12▾

Respiratory11▾

Abdominal and Gastrointestinal24▾

Renal and Urinary7▾

Neurologic11▾

Back and Neck8▾

Women's Health, Pregnancy, and GU11▾

Infectious Disease and Fever Syndromes11▾

Allergy and Dermatology7▾

Musculoskeletal and Extremities14▾

Trauma and Wounds14▾

ENT, Eye, Dental10▾

Endocrine, Metabolic, and Abnormal Labs9▾

Toxicology and Behavioral14▾

Undifferentiated Overdose Opioid Toxicity Opioid Withdrawal Alcohol Intoxication Alcohol Withdrawal Stimulant Toxicity Pediatric Ingestion Carbon Monoxide Exposure Inhalational Or Chemical Exposure Suicidal Ideation And Self Harm Risk Assessment Acute Psychosis And Mania Symptoms Anxiety And Panic Symptoms Capacity Assessment And Safe Disposition Behavioral Escalation And Restraint Considerations

Pediatrics16▾

Environmental and Exposure4▾

01History/hx91

Exposure context

›Exposure context

›Agent name if known

›Trade name or product label if known

›Intended use

›Route

›Inhalation

›Ocular

›Dermal

›Ingestion

›Setting

›Enclosed space

›Industrial

›Household

›Fire or smoke

›Chemical release

›Duration of exposure

›Proximity to source

›Ventilation quality

›Protective equipment used

›Others exposed

›Patient removed from source time

›Decontamination performed pre arrival

HPI

›Symptom overview

›Primary symptom

›Time course

›Trajectory

›Prior similar episodes

›Baseline cardiopulmonary status

OPQRST

›OPQRST

›Onset

›Time from exposure to symptoms

›Sudden versus gradual

›Provocation and palliation

›Worse with exertion

›Worse when supine

›Improved after leaving area

›Improved with oxygen

›Quality

›Dyspnea

›Chest tightness

›Throat irritation

›Burning eyes

›Headache

›Region and radiation

›Upper airway

›Chest

›Eyes

›Skin

›Severity

›Functional limitation

›Speech limitation

›Timing

›Continuous versus intermittent

›Delayed onset after exposure

Associated symptoms

›Associated symptoms

›Headache

›Dizziness

›Nausea

›Vomiting

›Confusion

›Syncope

›Seizure

›Cough

›Wheeze

›Stridor

›Chest pain

›Palpitations

›Fever

›Soot in sputum

›Hoarseness

Agent specific prompts

›Agent specific prompts

›Carbon monoxide exposure clues

›Combustion sources

›Winter heating

›Multiple household members symptomatic

›Cyanide exposure clues

›Enclosed space fire

›Synthetic material combustion

›Irritant gas clues

›Chlorine or bleach mixing

›Ammonia mixing

›Hydrogen sulfide clues

›Sewer

›Manure pit

›Petroleum refining

›Nitrogen dioxide or silo filler clues

›Agricultural exposure

›Delayed pulmonary symptoms

›Solvent inhalation clues

›Intentional inhalant use

›Occupational degreaser exposure

02Alarm Features/alarm40

Immediate resuscitation triggers

›Immediate resuscitation triggers

›Airway compromise

›Stridor

›Inability to protect airway

›Respiratory failure

›SpO2 below 90 percent on oxygen

›Rising PaCO2 on blood gas

›Hemodynamic instability

›SBP below 90 mmHg

›Shock index above 1

›Neurologic emergency

›GCS below 13

›Seizure

›Persistent altered mental status

›High risk exposure history

›Enclosed space fire

›Collapse in confined space

High risk tox syndromes

›High risk tox syndromes

›Carbon monoxide

›Syncope

›Ischemic chest pain

›Pregnancy exposure

›Cyanide

›Severe lactic acidosis

›Cardiovascular collapse

›Caustic inhalation

›Progressive upper airway edema

›Delayed noncardiogenic pulmonary edema

High risk exam findings

›High risk exam findings

›Facial or airway burns

›Soot in nares or oropharynx

›Hoarseness

›Drooling

›Severe bronchospasm

›Rales consistent with pulmonary edema

›Cyanosis not improving with oxygen

Pediatric and pregnancy red flags

›Pediatric and pregnancy red flags

›Pregnancy with suspected carbon monoxide

›Infant with apnea

›Child with altered mental status after exposure

03Medications/meds39

Home and recent exposures

›Home and recent exposures

›Prescribed medications

›OTC medications

›Supplements and herbals

›Recent medication changes

›Non prescribed substances

›Inhalants

›Recreational drugs

High risk interactions for anticipated therapies

›High risk interactions for anticipated therapies

›QT prolonging agents

›Beta blocker use

›MAOI use

›Chronic opioid use

ED therapies commonly used

›ED therapies commonly used

›Oxygen therapy

›Non rebreather 15 L per minute

›High flow nasal cannula local protocol dependent

›Bronchodilators

›Salbutamol inhaled 4 to 8 puffs via MDI spacer

›Salbutamol nebulized 5 mg

›Corticosteroids for reactive airway phenotype

›Dexamethasone PO or IV 10 mg

›Prednisone PO 50 mg

›Nebulized epinephrine for upper airway edema

›Racemic epinephrine nebulized local protocol dependent

›L epinephrine nebulized local protocol dependent

Antidotes and targeted agents

›Antidotes and targeted agents

›Hydroxocobalamin for suspected cyanide

›Adult 5 g IV over 15 minutes

›Repeat 5 g IV if ongoing life threats

›Methylene blue for significant methemoglobinemia

›Adult 1 mg per kg IV over 5 minutes

›Repeat 1 mg per kg after 30 to 60 minutes if needed

›Atropine for cholinergic toxidrome

›Adult 2 mg IV

›Doubling dose every 3 to 5 minutes until secretions controlled

›Pralidoxime for organophosphate poisoning

›Adult 1 to 2 g IV over 15 to 30 minutes

›Infusion 500 mg per hour local protocol dependent

04Diet/diet9

Recent intake and vulnerabilities

›Recent intake and vulnerabilities

›Poor oral intake

›Vomiting with dehydration

›Heavy exertion before exposure

›Alcohol intake

Caffeine and stimulant use

›Caffeine and stimulant use

›Energy drinks

›Prescription stimulants

›Illicit stimulants

05Review of Systems/ros31

Respiratory

›Respiratory

›Dyspnea

›Cough

›Wheeze

›Hemoptysis

›Chest tightness

›Pleurtic pain

ENT and ocular

›ENT and ocular

›Sore throat

›Hoarseness

›Dysphagia

›Eye pain

›Tearing

›Photophobia

Neurologic

›Neurologic

›Headache

›Dizziness

›Confusion

›Syncope

›Seizure

›Focal deficits

Cardiovascular

›Cardiovascular

›Chest pain

›Palpitations

›Dyspnea on exertion

›Edema

Constitutional and infection

›Constitutional and infection

›Fever

›Chills

›Myalgias

›Sick contacts

06Collateral History and Family History/chafh14

Collateral source

›Collateral source

›EMS report

›Fire or hazmat report

›Workplace supervisor

›Family or bystanders

Family history relevant to outcomes

›Family history relevant to outcomes

›Premature coronary artery disease

›Asthma

›Hemoglobinopathy

›G6PD deficiency

Household and community exposure

›Household and community exposure

›Multiple symptomatic persons

›Similar symptoms at same location

›Pets affected

07Risk Factors/rf20

Patient factors increasing susceptibility

›Patient factors increasing susceptibility

›Pregnancy

›Age over 65 years

›Infancy

›Chronic lung disease

›Coronary artery disease

›Heart failure

›Anemia

Exposure risks

›Exposure risks

›Enclosed space exposure

›Industrial release

›Fire smoke exposure

›Inhalant misuse

Occupational and environmental risks

›Occupational and environmental risks

›Confined space work

›Agricultural silo exposure

›Wastewater and sewer work

Procedure and device related

›Procedure and device related

›Methylene chloride paint stripper exposure

›Home generator use

08Differential Diagnosis/ddx55

Life threatening

›Life threatening

›Airway edema with impending obstruction

›Stridor

›Voice change

›Severe bronchospasm

›Silent chest

›Rising PaCO2

›Noncardiogenic pulmonary edema

›Delayed onset after irritant gas

›Hypoxemia refractory to bronchodilator

›Carbon monoxide poisoning (T58)

›Headache with exposure

›Syncope

›Cyanide poisoning (T65.3)

›Severe lactic acidosis

›Cardiovascular collapse

›Hydrogen sulfide poisoning (T59.6)

›Sudden collapse in confined space

›Seizure

›Methemoglobinemia (T65.9)

›Cyanosis with normal PaO2

›Chocolate colored blood

›Acute coronary syndrome (I21.9)

›Chest pain

›ECG ischemia

Common

›Common

›Irritant induced bronchitis

›Cough

›Throat irritation

›Reactive airway exacerbation (J45.901)

›Wheeze

›Response to bronchodilator

›Chemical conjunctivitis

›Eye irritation

›Tearing

›Anxiety or hyperventilation

›Paresthesias

›Normal objective findings

Less common

›Less common

›Hypersensitivity pneumonitis (J67.9)

›Exposure pattern

›Interstitial findings

›Aspiration pneumonitis (J69.0)

›Vomiting

›Focal infiltrate

›Pulmonary embolism (I26.99)

›Pleuritic pain

›Risk factors

Mimics and pitfalls

›Mimics and pitfalls

›Normal pulse oximetry in carbon monoxide

›SpO2 may appear normal

›Co oximetry required

›Delayed toxicity after certain gases

›Phosgene

›Nitrogen dioxide

09Past Medical History/pmh13

Relevant chronic conditions

›Relevant chronic conditions

›Asthma (J45.909)

›COPD (J44.9)

›Coronary artery disease (I25.10)

›Heart failure (I50.9)

›Chronic kidney disease (N18.9)

Prior episodes and complications

›Prior episodes and complications

›Prior chemical exposure reactions

›Prior intubation for asthma

›Prior hyperbaric oxygen therapy

Procedures and devices

›Procedures and devices

›Home oxygen use

›CPAP use

10Physical Exam/exam43

General and vitals interpretation

›General and vitals interpretation

›Work of breathing

›Ability to speak full sentences

›Mental status

›Odor on clothing

›Temperature pattern

›Hypotension pattern

›Tachycardia pattern

Airway and ENT

›Airway and ENT

›Stridor

›Hoarseness

›Drooling

›Oropharyngeal erythema

›Soot in nares or oropharynx

Respiratory

›Respiratory

›Wheeze

›Prolonged expiratory phase

›Rales

›Silent chest

›Accessory muscle use

›Peak flow if feasible

Cardiovascular

›Cardiovascular

›Perfusion

›Capillary refill

›New murmur

›Signs of heart failure

Neurologic

›Neurologic

›GCS

›Focal deficits

›Ataxia

›Seizure activity

Skin and eyes

›Skin and eyes

›Eye injection

›Tearing

›Dermal burns

›Chemical residue

Toxidrome pattern recognition

›Toxidrome pattern recognition

›Cholinergic

›Bronchorrhea

›Bradycardia

›Hypoxic toxidrome

›Cyanosis

›Altered mental status

11Lab Studies/labs29

Core labs for undifferentiated exposure

›Core labs for undifferentiated exposure

›Glucose point of care

›CBC

›Electrolytes and renal function

›Liver enzymes

›Lactate mmol per L

›Creatine kinase

Blood gas and co oximetry

›Blood gas and co oximetry

›VBG or ABG with pH and PaCO2 mmHg

›Co oximetry panel when available

›Carboxyhemoglobin percent

›Methemoglobin percent

Cardiac and pulmonary risk evaluation

›Cardiac and pulmonary risk evaluation

›Troponin for chest pain or hypoxia

›BNP for pulmonary edema phenotype

Targeted labs by suspected agent

›Targeted labs by suspected agent

›Carbon monoxide

›Carboxyhemoglobin percent baseline

›Repeat after therapy if clinically indicated

›Cyanide

›Lactate trend mmol per L

›Severe lactate suggests high risk toxicity

›Methemoglobinemia

›Methemoglobin percent level

›Correlate with symptoms not oximetry

Pitfalls and limitations

›Pitfalls and limitations

›Carboxyhemoglobin decreases rapidly on oxygen

›Pulse oximetry may be unreliable in dyshemoglobinemias

›Cyanide blood levels often not timely for acute decisions

12Imaging/img15

Scoring Systems

›Scoring Systems

›Carbon monoxide severity stratification local protocol dependent

›Inhalation injury grading by bronchoscopy local protocol dependent

MRI

›MRI

›Brain MRI for delayed neuropsychiatric syndrome local protocol dependent

›Timing typically days to weeks after carbon monoxide exposure

›CT

›CT chest for worsening hypoxemia with unclear cause

›CT neck for suspected deep airway injury local protocol dependent

Ultrasound

›Ultrasound

›Lung ultrasound for pulmonary edema pattern

›Cardiac POCUS for myocardial dysfunction in severe hypoxia

Radiography

›Radiography

›Chest radiograph for hypoxemia or persistent cough

›Repeat imaging for delayed pulmonary edema risk exposures

13Special Tests/spec13

Bedside functional testing

›Bedside functional testing

›Peak expiratory flow for asthma phenotype

›Serial respiratory assessment for fatigue

Airway evaluation

›Airway evaluation

›Flexible nasopharyngolaryngoscopy for suspected upper airway edema local protocol dependent

›Early anesthesia or ENT involvement for evolving edema

Bronchoscopy

›Bronchoscopy

›Inhalation injury assessment in fire smoke exposure local protocol dependent

›Suctioning of soot or casts when indicated

Decontamination considerations

›Decontamination considerations

›Remove contaminated clothing

›Irrigate eyes for chemical exposure

›Skin irrigation with copious water for particulate or liquid exposure

14ECG/ecg12

Indications

›Indications

›Carbon monoxide suspected or confirmed

›Chest pain

›Syncope

›Significant hypoxemia

High risk patterns

›High risk patterns

›Ischemic ST changes

›Ventricular dysrhythmia

›QT prolongation

Serial ECG logic

›Serial ECG logic

›If ongoing symptoms or elevated troponin repeat ECG

›If carbon monoxide with cardiac symptoms repeat ECG during observation

15Assessment/ax21

Problem representation

›Problem representation

›Exposure type and suspected agent

›Primary syndrome

›Upper airway injury

›Bronchospasm

›Hypoxic toxidrome

›Dyshemoglobinemia

›Severity

›Mild symptoms with normal vitals

›Hypoxemia requiring oxygen

›Life threatening features

Complications to rule out

›Complications to rule out

›Airway obstruction progression

›Delayed pulmonary edema

›Myocardial ischemia

›Seizure recurrence

›Rhabdomyolysis

Diagnostic uncertainty

›Diagnostic uncertainty

›Mixed exposure possibility

›Time from exposure affecting test sensitivity

›Alternative diagnoses if objective findings absent

16Plan/plan53

First 5 minutes

›First 5 minutes

›PPE and secondary contamination prevention

›Remove from exposure source if not already

›Oxygen

›Non rebreather 15 L per minute

›Escalate to NIV if impending fatigue and no contraindication

›Monitoring

›Cardiac monitor

›Continuous pulse oximetry

›Capnography if ventilatory concern

›IV access

›Two large bore IV if unstable

›One IV if stable

›Glucose point of care

›Immediate airway plan if stridor or declining mental status

Decontamination and scene coordination

›Decontamination and scene coordination

›Clothing removal and bagging

›Skin irrigation if particulate or liquid contamination

›Eye irrigation for ocular symptoms

›Notify hazmat when ongoing off gassing concern

Targeted therapy by syndrome

›Targeted therapy by syndrome

›Irritant gas bronchospasm

›Salbutamol therapy

›Ipratropium add on for moderate to severe bronchospasm

›Upper airway edema

›Nebulized epinephrine local protocol dependent

›Early intubation if progressive stridor

›Carbon monoxide

›100 percent oxygen until symptom free

›Consider hyperbaric oxygen when severe features present local protocol dependent

›Suspected cyanide

›Hydroxocobalamin if life threatening smoke inhalation syndrome

›Vasopressors for refractory hypotension

›Methemoglobinemia

›Methylene blue if symptomatic or high level local protocol dependent

›Avoid in known G6PD deficiency when possible

›Cholinergic toxidrome

›Atropine titration to secretion control

›Pralidoxime when organophosphate suspected

Ventilation and oxygenation escalation

›Ventilation and oxygenation escalation

›If refractory hypoxemia escalate to high flow nasal cannula

›If rising PaCO2 or fatigue prepare for intubation

Consultation and resources

›Consultation and resources

›Poison centre consultation early

›Hyperbaric centre consultation for severe carbon monoxide local protocol dependent

›Burn centre consultation for inhalation injury local protocol dependent

›Critical care consultation for ventilatory failure or shock

Reassessment loop

›Reassessment loop

›Recheck vitals every 15 to 30 minutes until stable

›Repeat lung exam after bronchodilator

›Repeat neurologic exam for carbon monoxide

›Repeat blood gas if worsening work of breathing

›Repeat lactate in suspected cyanide or shock

17Disposition/dispo26

ICU criteria

›ICU criteria

›Intubation or impending airway compromise

›Shock requiring vasopressors

›Severe hypoxemia requiring NIV or high flow with instability

›Seizure or persistent altered mental status

›Severe metabolic acidosis

Inpatient admission criteria

›Inpatient admission criteria

›Persistent oxygen requirement

›Abnormal chest radiograph

›Elevated troponin with carbon monoxide

›Significant bronchospasm requiring frequent therapy

›Social reliability concerns with delayed toxicity risk

Observation pathway criteria

›Observation pathway criteria

›Irritant gas exposure with improving symptoms

›Serial exams for delayed pulmonary edema risk

›Carbon monoxide with resolved symptoms after oxygen and stable exams

Discharge criteria

›Discharge criteria

›Symptom resolution at rest

›Normal work of breathing

›Stable vitals

›No new wheeze after observation period

›Clear follow up plan

Time windows for delayed effects

›Time windows for delayed effects

›Irritant gases may worsen over 6 to 24 hours

›Phosgene or nitrogen dioxide may have delayed pulmonary edema up to 24 hours

›Carbon monoxide delayed neuropsychiatric syndrome days to weeks

18Discharge Instructions/di12

Copy discharge instructions

›Copy discharge instructions

›You were treated for symptoms after breathing in a chemical or smoke exposure

›Return immediately if breathing worsens

›Return immediately if you develop noisy breathing or trouble swallowing

›Return immediately if chest pain occurs

›Return immediately if you faint or feel confused

›Return immediately if vomiting prevents drinking fluids

›Avoid the exposure location until it has been cleared as safe

›Avoid smoking and strong fumes for 48 hours

›Use inhalers exactly as prescribed if provided

›Follow up with your primary care clinician within 24 to 72 hours

›If carbon monoxide exposure occurred have the source inspected before returning

19References/r7

Key guidelines and references

›Key guidelines and references

›CDC clinical guidance for carbon monoxide poisoning 2024

›Undersea and Hyperbaric Medical Society carbon monoxide poisoning indications 2020

›American Heart Association focused update on poisoning related life threatening toxicity 2023

›Ontario Poison Centre carbon monoxide protocol 2024

›ATSDR toxicological profile for carbon monoxide 2012

›Canadian Undersea and Hyperbaric Medical Association standards of practice guidelines 2016

Evidence & Review

Reviewed by SymptomDx Medical Team · Last reviewed February 24, 2026

SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.

Inhalational Or Chemical ExposureAPPROACH

TOXICOLOGY AND BEHAVIORAL · 19 SECTIONS

⚲

543 items

☷ Legend

⚲

Resuscitation and Universal Approaches9▾

Chest and Cardiovascular12▾

Respiratory11▾

Abdominal and Gastrointestinal24▾

Renal and Urinary7▾

Neurologic11▾

Back and Neck8▾

Women's Health, Pregnancy, and GU11▾

Infectious Disease and Fever Syndromes11▾

Allergy and Dermatology7▾

Musculoskeletal and Extremities14▾

Trauma and Wounds14▾

ENT, Eye, Dental10▾

Endocrine, Metabolic, and Abnormal Labs9▾

Toxicology and Behavioral14▾

Pediatrics16▾

Environmental and Exposure4▾

01History/hx91

Exposure context

›Exposure context

›Agent name if known

›Trade name or product label if known

›Intended use

›Route

›Inhalation

›Ocular

›Dermal

›Ingestion

›Setting

›Enclosed space

›Industrial

›Household

›Fire or smoke

›Chemical release

›Duration of exposure

›Proximity to source

›Ventilation quality

›Protective equipment used

›Others exposed

›Patient removed from source time

›Decontamination performed pre arrival

HPI

›Symptom overview

›Primary symptom

›Time course

›Trajectory

›Prior similar episodes

›Baseline cardiopulmonary status

OPQRST

›OPQRST

›Onset

›Time from exposure to symptoms

›Sudden versus gradual

›Provocation and palliation

›Worse with exertion

›Worse when supine

›Improved after leaving area

›Improved with oxygen

›Quality

›Dyspnea

›Chest tightness

›Throat irritation

›Burning eyes

›Headache

›Region and radiation

›Upper airway

›Chest

›Eyes

›Skin

›Severity

›Functional limitation

›Speech limitation

›Timing

›Continuous versus intermittent

›Delayed onset after exposure

Associated symptoms

›Associated symptoms

›Headache

›Dizziness

›Nausea

›Vomiting

›Confusion

›Syncope

›Seizure

›Cough

›Wheeze

›Stridor

›Chest pain

›Palpitations

›Fever

›Soot in sputum

›Hoarseness

Agent specific prompts

›Agent specific prompts

›Carbon monoxide exposure clues

›Combustion sources

›Winter heating

›Multiple household members symptomatic

›Cyanide exposure clues

›Enclosed space fire

›Synthetic material combustion

›Irritant gas clues

›Chlorine or bleach mixing

›Ammonia mixing

›Hydrogen sulfide clues

›Sewer

›Manure pit

›Petroleum refining

›Nitrogen dioxide or silo filler clues

›Agricultural exposure

›Delayed pulmonary symptoms

›Solvent inhalation clues

›Intentional inhalant use

›Occupational degreaser exposure

02Alarm Features/alarm40

Immediate resuscitation triggers

›Immediate resuscitation triggers

›Airway compromise

›Stridor

›Inability to protect airway

›Respiratory failure

›SpO2 below 90 percent on oxygen

›Rising PaCO2 on blood gas

›Hemodynamic instability

›SBP below 90 mmHg

›Shock index above 1

›Neurologic emergency

›GCS below 13

›Seizure

›Persistent altered mental status

›High risk exposure history

›Enclosed space fire

›Collapse in confined space

High risk tox syndromes

›High risk tox syndromes

›Carbon monoxide

›Syncope

›Ischemic chest pain

›Pregnancy exposure

›Cyanide

›Severe lactic acidosis

›Cardiovascular collapse

›Caustic inhalation

›Progressive upper airway edema

›Delayed noncardiogenic pulmonary edema

High risk exam findings

›High risk exam findings

›Facial or airway burns

›Soot in nares or oropharynx

›Hoarseness

›Drooling

›Severe bronchospasm

›Rales consistent with pulmonary edema

›Cyanosis not improving with oxygen

Pediatric and pregnancy red flags

›Pediatric and pregnancy red flags

›Pregnancy with suspected carbon monoxide

›Infant with apnea

›Child with altered mental status after exposure

03Medications/meds39

Home and recent exposures

›Home and recent exposures

›Prescribed medications

›OTC medications

›Supplements and herbals

›Recent medication changes

›Non prescribed substances

›Inhalants

›Recreational drugs

High risk interactions for anticipated therapies

›High risk interactions for anticipated therapies

›QT prolonging agents

›Beta blocker use

›MAOI use

›Chronic opioid use

ED therapies commonly used

›ED therapies commonly used

›Oxygen therapy

›Non rebreather 15 L per minute

›High flow nasal cannula local protocol dependent

›Bronchodilators

›Salbutamol inhaled 4 to 8 puffs via MDI spacer

›Salbutamol nebulized 5 mg

›Corticosteroids for reactive airway phenotype

›Dexamethasone PO or IV 10 mg

›Prednisone PO 50 mg

›Nebulized epinephrine for upper airway edema

›Racemic epinephrine nebulized local protocol dependent

›L epinephrine nebulized local protocol dependent

Antidotes and targeted agents

›Antidotes and targeted agents

›Hydroxocobalamin for suspected cyanide

›Adult 5 g IV over 15 minutes

›Repeat 5 g IV if ongoing life threats

›Methylene blue for significant methemoglobinemia

›Adult 1 mg per kg IV over 5 minutes

›Repeat 1 mg per kg after 30 to 60 minutes if needed

›Atropine for cholinergic toxidrome

›Adult 2 mg IV

›Doubling dose every 3 to 5 minutes until secretions controlled

›Pralidoxime for organophosphate poisoning

›Adult 1 to 2 g IV over 15 to 30 minutes

›Infusion 500 mg per hour local protocol dependent

04Diet/diet9

Recent intake and vulnerabilities

›Recent intake and vulnerabilities

›Poor oral intake

›Vomiting with dehydration

›Heavy exertion before exposure

›Alcohol intake

Caffeine and stimulant use

›Caffeine and stimulant use

›Energy drinks

›Prescription stimulants

›Illicit stimulants

05Review of Systems/ros31

Respiratory

›Respiratory

›Dyspnea

›Cough

›Wheeze

›Hemoptysis

›Chest tightness

›Pleurtic pain

ENT and ocular

›ENT and ocular

›Sore throat

›Hoarseness

›Dysphagia

›Eye pain

›Tearing

›Photophobia

Neurologic

›Neurologic

›Headache

›Dizziness

›Confusion

›Syncope

›Seizure

›Focal deficits

Cardiovascular

›Cardiovascular

›Chest pain

›Palpitations

›Dyspnea on exertion

›Edema

Constitutional and infection

›Constitutional and infection

›Fever

›Chills

›Myalgias

›Sick contacts

06Collateral History and Family History/chafh14

Collateral source

›Collateral source

›EMS report

›Fire or hazmat report

›Workplace supervisor

›Family or bystanders

Family history relevant to outcomes

›Family history relevant to outcomes

›Premature coronary artery disease

›Asthma

›Hemoglobinopathy

›G6PD deficiency

Household and community exposure

›Household and community exposure

›Multiple symptomatic persons

›Similar symptoms at same location

›Pets affected

07Risk Factors/rf20

Patient factors increasing susceptibility

›Patient factors increasing susceptibility

›Pregnancy

›Age over 65 years

›Infancy

›Chronic lung disease

›Coronary artery disease

›Heart failure

›Anemia

Exposure risks

›Exposure risks

›Enclosed space exposure

›Industrial release

›Fire smoke exposure

›Inhalant misuse

Occupational and environmental risks

›Occupational and environmental risks

›Confined space work

›Agricultural silo exposure

›Wastewater and sewer work

Procedure and device related

›Procedure and device related

›Methylene chloride paint stripper exposure

›Home generator use

08Differential Diagnosis/ddx55

Life threatening

›Life threatening

›Airway edema with impending obstruction

›Stridor

›Voice change

›Severe bronchospasm

›Silent chest

›Rising PaCO2

›Noncardiogenic pulmonary edema

›Delayed onset after irritant gas

›Hypoxemia refractory to bronchodilator

›Carbon monoxide poisoning (T58)

›Headache with exposure

›Syncope

›Cyanide poisoning (T65.3)

›Severe lactic acidosis

›Cardiovascular collapse

›Hydrogen sulfide poisoning (T59.6)

›Sudden collapse in confined space

›Seizure

›Methemoglobinemia (T65.9)

›Cyanosis with normal PaO2

›Chocolate colored blood

›Acute coronary syndrome (I21.9)

›Chest pain

›ECG ischemia

Common

›Common

›Irritant induced bronchitis

›Cough

›Throat irritation

›Reactive airway exacerbation (J45.901)

›Wheeze

›Response to bronchodilator

›Chemical conjunctivitis

›Eye irritation

›Tearing

›Anxiety or hyperventilation

›Paresthesias

›Normal objective findings

Less common

›Less common

›Hypersensitivity pneumonitis (J67.9)

›Exposure pattern

›Interstitial findings

›Aspiration pneumonitis (J69.0)

›Vomiting

›Focal infiltrate

›Pulmonary embolism (I26.99)

›Pleuritic pain

›Risk factors

Mimics and pitfalls

›Mimics and pitfalls

›Normal pulse oximetry in carbon monoxide

›SpO2 may appear normal

›Co oximetry required

›Delayed toxicity after certain gases

›Phosgene

›Nitrogen dioxide

09Past Medical History/pmh13

Relevant chronic conditions

›Relevant chronic conditions

›Asthma (J45.909)

›COPD (J44.9)

›Coronary artery disease (I25.10)

›Heart failure (I50.9)

›Chronic kidney disease (N18.9)

Prior episodes and complications

›Prior episodes and complications

›Prior chemical exposure reactions

›Prior intubation for asthma

›Prior hyperbaric oxygen therapy

Procedures and devices

›Procedures and devices

›Home oxygen use

›CPAP use

10Physical Exam/exam43

General and vitals interpretation

›General and vitals interpretation

›Work of breathing

›Ability to speak full sentences

›Mental status

›Odor on clothing

›Temperature pattern

›Hypotension pattern

›Tachycardia pattern

Airway and ENT

›Airway and ENT

›Stridor

›Hoarseness

›Drooling

›Oropharyngeal erythema

›Soot in nares or oropharynx

Respiratory

›Respiratory

›Wheeze

›Prolonged expiratory phase

›Rales

›Silent chest

›Accessory muscle use

›Peak flow if feasible

Cardiovascular

›Cardiovascular

›Perfusion

›Capillary refill

›New murmur

›Signs of heart failure

Neurologic

›Neurologic

›GCS

›Focal deficits

›Ataxia

›Seizure activity

Skin and eyes

›Skin and eyes

›Eye injection

›Tearing

›Dermal burns

›Chemical residue

Toxidrome pattern recognition

›Toxidrome pattern recognition

›Cholinergic

›Bronchorrhea

›Bradycardia

›Hypoxic toxidrome

›Cyanosis

›Altered mental status

11Lab Studies/labs29

Core labs for undifferentiated exposure

›Core labs for undifferentiated exposure

›Glucose point of care

›CBC

›Electrolytes and renal function

›Liver enzymes

›Lactate mmol per L

›Creatine kinase

Blood gas and co oximetry

›Blood gas and co oximetry

›VBG or ABG with pH and PaCO2 mmHg

›Co oximetry panel when available

›Carboxyhemoglobin percent

›Methemoglobin percent

Cardiac and pulmonary risk evaluation

›Cardiac and pulmonary risk evaluation

›Troponin for chest pain or hypoxia

›BNP for pulmonary edema phenotype

Targeted labs by suspected agent

›Targeted labs by suspected agent

›Carbon monoxide

›Carboxyhemoglobin percent baseline

›Repeat after therapy if clinically indicated

›Cyanide

›Lactate trend mmol per L

›Severe lactate suggests high risk toxicity

›Methemoglobinemia

›Methemoglobin percent level

›Correlate with symptoms not oximetry

Pitfalls and limitations

›Pitfalls and limitations

›Carboxyhemoglobin decreases rapidly on oxygen

›Pulse oximetry may be unreliable in dyshemoglobinemias

›Cyanide blood levels often not timely for acute decisions

12Imaging/img15

Scoring Systems

›Scoring Systems

›Carbon monoxide severity stratification local protocol dependent

›Inhalation injury grading by bronchoscopy local protocol dependent

MRI

›MRI

›Brain MRI for delayed neuropsychiatric syndrome local protocol dependent

›Timing typically days to weeks after carbon monoxide exposure

›CT

›CT chest for worsening hypoxemia with unclear cause

›CT neck for suspected deep airway injury local protocol dependent

Ultrasound

›Ultrasound

›Lung ultrasound for pulmonary edema pattern

›Cardiac POCUS for myocardial dysfunction in severe hypoxia

Radiography

›Radiography

›Chest radiograph for hypoxemia or persistent cough

›Repeat imaging for delayed pulmonary edema risk exposures

13Special Tests/spec13

Bedside functional testing

›Bedside functional testing

›Peak expiratory flow for asthma phenotype

›Serial respiratory assessment for fatigue

Airway evaluation

›Airway evaluation

›Flexible nasopharyngolaryngoscopy for suspected upper airway edema local protocol dependent

›Early anesthesia or ENT involvement for evolving edema

Bronchoscopy

›Bronchoscopy

›Inhalation injury assessment in fire smoke exposure local protocol dependent

›Suctioning of soot or casts when indicated

Decontamination considerations

›Decontamination considerations

›Remove contaminated clothing

›Irrigate eyes for chemical exposure

›Skin irrigation with copious water for particulate or liquid exposure

14ECG/ecg12

Indications

›Indications

›Carbon monoxide suspected or confirmed

›Chest pain

›Syncope

›Significant hypoxemia

High risk patterns

›High risk patterns

›Ischemic ST changes

›Ventricular dysrhythmia

›QT prolongation

Serial ECG logic

›Serial ECG logic

›If ongoing symptoms or elevated troponin repeat ECG

›If carbon monoxide with cardiac symptoms repeat ECG during observation

15Assessment/ax21

Problem representation

›Problem representation

›Exposure type and suspected agent

›Primary syndrome

›Upper airway injury

›Bronchospasm

›Hypoxic toxidrome

›Dyshemoglobinemia

›Severity

›Mild symptoms with normal vitals

›Hypoxemia requiring oxygen

›Life threatening features

Complications to rule out

›Complications to rule out

›Airway obstruction progression

›Delayed pulmonary edema

›Myocardial ischemia

›Seizure recurrence

›Rhabdomyolysis

Diagnostic uncertainty

›Diagnostic uncertainty

›Mixed exposure possibility

›Time from exposure affecting test sensitivity

›Alternative diagnoses if objective findings absent

16Plan/plan53

First 5 minutes

›First 5 minutes

›PPE and secondary contamination prevention

›Remove from exposure source if not already

›Oxygen

›Non rebreather 15 L per minute

›Escalate to NIV if impending fatigue and no contraindication

›Monitoring

›Cardiac monitor

›Continuous pulse oximetry

›Capnography if ventilatory concern

›IV access

›Two large bore IV if unstable

›One IV if stable

›Glucose point of care

›Immediate airway plan if stridor or declining mental status

Decontamination and scene coordination

›Decontamination and scene coordination

›Clothing removal and bagging

›Skin irrigation if particulate or liquid contamination

›Eye irrigation for ocular symptoms

›Notify hazmat when ongoing off gassing concern

Targeted therapy by syndrome

›Targeted therapy by syndrome

›Irritant gas bronchospasm

›Salbutamol therapy

›Ipratropium add on for moderate to severe bronchospasm

›Upper airway edema

›Nebulized epinephrine local protocol dependent

›Early intubation if progressive stridor

›Carbon monoxide

›100 percent oxygen until symptom free

›Consider hyperbaric oxygen when severe features present local protocol dependent

›Suspected cyanide

›Hydroxocobalamin if life threatening smoke inhalation syndrome

›Vasopressors for refractory hypotension

›Methemoglobinemia

›Methylene blue if symptomatic or high level local protocol dependent

›Avoid in known G6PD deficiency when possible

›Cholinergic toxidrome

›Atropine titration to secretion control

›Pralidoxime when organophosphate suspected

Ventilation and oxygenation escalation

›Ventilation and oxygenation escalation

›If refractory hypoxemia escalate to high flow nasal cannula

›If rising PaCO2 or fatigue prepare for intubation

Consultation and resources

›Consultation and resources

›Poison centre consultation early

›Hyperbaric centre consultation for severe carbon monoxide local protocol dependent

›Burn centre consultation for inhalation injury local protocol dependent

›Critical care consultation for ventilatory failure or shock

Reassessment loop

›Reassessment loop

›Recheck vitals every 15 to 30 minutes until stable

›Repeat lung exam after bronchodilator

›Repeat neurologic exam for carbon monoxide

›Repeat blood gas if worsening work of breathing

›Repeat lactate in suspected cyanide or shock

17Disposition/dispo26

ICU criteria

›ICU criteria

›Intubation or impending airway compromise

›Shock requiring vasopressors

›Severe hypoxemia requiring NIV or high flow with instability

›Seizure or persistent altered mental status

›Severe metabolic acidosis

Inpatient admission criteria

›Inpatient admission criteria

›Persistent oxygen requirement

›Abnormal chest radiograph

›Elevated troponin with carbon monoxide

›Significant bronchospasm requiring frequent therapy

›Social reliability concerns with delayed toxicity risk

Observation pathway criteria

›Observation pathway criteria

›Irritant gas exposure with improving symptoms

›Serial exams for delayed pulmonary edema risk

›Carbon monoxide with resolved symptoms after oxygen and stable exams

Discharge criteria

›Discharge criteria

›Symptom resolution at rest

›Normal work of breathing

›Stable vitals

›No new wheeze after observation period

›Clear follow up plan

Time windows for delayed effects

›Time windows for delayed effects

›Irritant gases may worsen over 6 to 24 hours

›Phosgene or nitrogen dioxide may have delayed pulmonary edema up to 24 hours

›Carbon monoxide delayed neuropsychiatric syndrome days to weeks

18Discharge Instructions/di12

Copy discharge instructions

›Copy discharge instructions

›You were treated for symptoms after breathing in a chemical or smoke exposure

›Return immediately if breathing worsens

›Return immediately if you develop noisy breathing or trouble swallowing

›Return immediately if chest pain occurs

›Return immediately if you faint or feel confused

›Return immediately if vomiting prevents drinking fluids

›Avoid the exposure location until it has been cleared as safe

›Avoid smoking and strong fumes for 48 hours

›Use inhalers exactly as prescribed if provided

›Follow up with your primary care clinician within 24 to 72 hours

›If carbon monoxide exposure occurred have the source inspected before returning

19References/r7

Key guidelines and references

›Key guidelines and references

›CDC clinical guidance for carbon monoxide poisoning 2024

›Undersea and Hyperbaric Medical Society carbon monoxide poisoning indications 2020

›American Heart Association focused update on poisoning related life threatening toxicity 2023

›Ontario Poison Centre carbon monoxide protocol 2024

›ATSDR toxicological profile for carbon monoxide 2012

›Canadian Undersea and Hyperbaric Medical Association standards of practice guidelines 2016

Evidence & Review

Reviewed by SymptomDx Medical Team · Last reviewed February 24, 2026

SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.