Carbon Monoxide ExposureAPPROACH

TOXICOLOGY AND BEHAVIORAL · 19 SECTIONS

⚲

570 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/hx68

Exposure context

›Carbon monoxide exposure context

›Location type

›Home

›Garage

›Workplace

›Vehicle

›Fire or smoke exposure

›Exposure scenario

›Enclosed space

›Multiple people symptomatic

›Pets symptomatic

›Recent use

›Furnace or boiler

›Space heater

›Generator

›Grill or charcoal

›Fireplace

›Gas stove or oven

›Timeline

›Time of last known well

›Estimated duration of exposure

›Time since removal from source

›Prehospital care

›Oxygen given

›Time on oxygen before labs

Symptom characterization

›Symptom profile

›Associated symptoms

›Headache

›Dizziness

›Nausea

›Vomiting

›Weakness

›Chest pain

›Dyspnea

›Confusion

›Syncope

›Seizure

›Symptom trajectory

›Improving after fresh air or oxygen

›Persistent despite oxygen

›Functional impact

›Unable to ambulate normally

›Unable to maintain oral intake

OPQRST if prominent symptom

›OPQRST for dominant symptom

›Onset

›Sudden

›Gradual

›Time of onset relative to exposure

›Provocation or palliation

›Worse in enclosed space

›Better outdoors

›Better with oxygen

›Quality

›Pressure

›Throbbing

›Shortness of breath sensation

›Region or radiation

›Frontal

›Diffuse

›Chest radiation

›Severity

›Mild

›Moderate

›Severe

›Timing

›Constant

›Intermittent

›Recurrent with re exposure

02Alarm Features/alarm28

Immediate life threats

›Critical features

›Airway compromise

›Inability to protect airway

›Recurrent vomiting with somnolence

›Respiratory failure

›SpO2 low on high flow oxygen

›Severe work of breathing

›Neurologic emergency

›Seizure

›Coma

›Focal neurologic deficit

›Cardiovascular emergency

›Chest pain concerning for ischemia

›Dysrhythmia

›Shock

High risk thresholds

›Escalation thresholds

›Systolic blood pressure less than 90 mmHg

›Escalate to resuscitation bay

›Vasopressor consideration after fluids

›Respiratory rate greater than 30

›Noninvasive ventilation consideration

›Early intubation consideration

›GCS less than 13

›Immediate airway readiness

›Immediate hyperbaric consultation consideration

›Persistent altered mental status

›Continuous monitoring

›Broaden differential and co ingestion workup

03Medications/meds28

Current and recent agents

›Medication reconciliation focus

›Cardioactive medications

›Beta blockers

›Calcium channel blockers

›Antiarrhythmics

›Sedatives and opioids

›Benzodiazepines

›Opioids

›Glucose lowering agents

›Insulin

›Sulfonylureas

›Anticoagulants and antiplatelets

›DOACs

›Warfarin

›Aspirin

›Recent changes

›Dose increase

›Missed doses

Treatment relevant contraindications

›Oxygen therapy considerations

›Severe COPD with chronic hypercapnia

›Titrate oxygen with ABG or VBG monitoring

›Ventilatory support thresholds

›Pregnancy status

›Lower threshold for hyperbaric consultation

›Fetal monitoring coordination

›Seizure history

›Hyperbaric seizure risk awareness

›Antiseizure medication adherence

04Diet/diet13

Recent intake and exposures

›Intake and exposure patterns

›Hydration status indicators

›Poor oral intake

›Vomiting limiting intake

›Alcohol exposure

›Recent ethanol intake

›Risk of co intoxication

›Caffeine and energy drinks

›High caffeine intake

›Palpitations confounders

›Carbon monoxide relevant environment

›Recent indoor cooking or heating

›Use of charcoal indoors

05Review of Systems/ros26

System symptom screen

›ROS clusters

›General

›Fatigue

›Malaise

›Fever

›Neurologic

›Headache

›Confusion

›Dizziness

›Visual changes

›Syncope

›Seizure

›Cardiopulmonary

›Chest pain

›Dyspnea

›Palpitations

›Gastrointestinal

›Nausea

›Vomiting

›Abdominal pain

›ENT

›Sore throat after smoke

›Hoarseness

›Dermatologic

›Burns or soot exposure

›Cyanosis

06Collateral History and Family History/chafh20

Collateral and scene information

›Collateral sources

›EMS report

›Scene description

›Other symptomatic occupants

›Fire department

›CO detector readings if available

›Environmental remediation status

›Family or roommates

›Shared symptom pattern

›Timing of symptom onset

Family history relevant to risk

›Family history considerations

›Early coronary artery disease

›First degree relative under 55 male

›First degree relative under 65 female

›Hemoglobinopathies

›Sickle cell disease

›Thalassemia

›Inherited arrhythmia syndromes

›Long QT syndrome

›Brugada syndrome

07Risk Factors/rf27

Exposure and environmental risks

›Exposure risk factors

›Enclosed space exposure

›Poor ventilation

›Sleeping during exposure

›Faulty combustion sources

›Furnace or boiler malfunction

›Generator indoors

›Vehicle running in garage

›Fire and smoke exposure

›Structural fire

›Wildfire smoke in enclosed space

Patient factors increasing harm

›High risk populations

›Pregnancy

›Increased fetal susceptibility

›Lower threshold for hyperbaric consultation

›Infants and children

›Higher minute ventilation

›Nonspecific symptom presentation

›Older adults

›Higher cardiac risk

›Baseline cognitive vulnerability

›Coronary artery disease (I25.10)

›Lower ischemia threshold

›Higher risk dysrhythmia

›Anemia (D64.9)

›Reduced oxygen carrying capacity

›More severe symptoms at lower COHb

08Differential Diagnosis/ddx45

Life threatening

›Life threatening causes

›Carbon monoxide poisoning (T58.91XA)

›Multiple occupants symptomatic

›Improvement with oxygen

›Cyanide toxicity

›Fire in enclosed space

›Severe lactic acidosis

›Acute coronary syndrome (I21.9)

›Chest pain

›ECG ischemia

›Stroke or TIA (I63.9)

›Focal deficits

›Persistent neurologic symptoms

›Severe hypoglycemia (E16.2)

›Diaphoresis

›Altered mental status

›Toxic co ingestion

›Sedative toxidrome

›Opioid toxidrome

Common

›Common alternatives

›Viral syndrome

›Fever

›Myalgias

›Migraine

›Photophobia

›Prior migraine history

›Gastroenteritis

›Diarrhea

›Sick contacts

›Anxiety or panic symptoms

›Hyperventilation

›Paresthesias

Less common

›Less common and mimics

›Methemoglobinemia

›Low SpO2 with normal PaO2

›Oxidant exposure

›Carbon dioxide exposure

›Confined space

›Headache with hypercapnia

›Meningitis or encephalitis (G00.9)

›Neck stiffness

›Persistent altered mental status

›Thyrotoxicosis (E05.90)

›Tremor

›Heat intolerance

09Past Medical History/pmh22

Relevant conditions and baseline

›Baseline risks and prior events

›Prior carbon monoxide exposure

›Prior hyperbaric treatment

›Delayed neuropsychiatric symptoms history

›Cardiopulmonary disease

›Coronary artery disease (I25.10)

›Heart failure (I50.9)

›COPD (J44.9)

›Asthma (J45.909)

›Neurologic disorders

›Seizure disorder (G40.909)

›Stroke history (I63.9)

›Hematologic conditions

›Anemia (D64.9)

›Sickle cell disease (D57.1)

Pregnancy and pediatric specifics

›Special populations baseline

›Pregnancy status

›Gestational age

›Obstetric complications

›Pediatrics

›Developmental baseline

›Baseline feeding pattern

10Physical Exam/exam39

Vitals and general appearance

›Immediate exam targets

›Vitals trends

›Temperature

›Heart rate

›Blood pressure

›Respiratory rate

›SpO2 on room air and on oxygen

›General appearance

›Toxic appearance

›Diaphoresis

›Altered level of consciousness

›Perfusion

›Capillary refill

›Skin temperature

›Peripheral pulses

Neurologic and cardiopulmonary

›System focused findings

›Neurologic

›GCS

›Orientation

›Cranial nerves

›Motor strength

›Sensation

›Coordination

›Gait if safe

›Cardiovascular

›Heart sounds

›Murmur

›Signs of heart failure

›JVP elevation

›Peripheral edema

›Crackles

›Respiratory

›Work of breathing

›Wheeze

›Crackles

›Soot in nares or oropharynx

›Skin

›Burns

›Soot contamination

11Lab Studies/labs34

Core labs and interpretation

›Key laboratory tests

›Carboxyhemoglobin level

›Venous acceptable for COHb trending

›Interpret with time on oxygen

›Blood gas

›ABG or VBG

›PaO2 in mmHg

›pH

›Lactate in mmol/L

›Basic metabolic panel

›Sodium in mmol/L

›Potassium in mmol/L

›Creatinine

›Glucose

›CBC

›Hemoglobin

›Leukocytosis context

›Troponin

›Chest pain

›Abnormal ECG

›Older adults

›CK

›Prolonged immobilization concern

›Seizure concern

Pitfalls and limitations

›Common interpretation pitfalls

›SpO2 limitation

›Pulse oximetry may read falsely normal

›Does not measure COHb

›COHb level limitations

›Lower after oxygen therapy

›Symptoms may not correlate with COHb

›Lactate interpretation

›High lactate suggests severe hypoxia

›Very high lactate in fire suggests cyanide co toxicity

12Imaging/img32

Scoring Systems

›Severity and pathway tools

›Hyperbaric referral triggers local protocol dependent

›Loss of consciousness

›Persistent neurologic symptoms

›Severe metabolic acidosis

›Pregnancy with elevated COHb

›Fire exposure adjunct risk assessment

›Soot in airway

›Facial burns

›Hoarseness or stridor

MRI

›Neuro imaging considerations

›MRI brain for delayed neuropsychiatric syndrome concern

›Cognitive change days to weeks after exposure

›Movement disorder symptoms

›MRI limitations

›Not required for typical acute management

›Timing dependent findings

›CT indications

›CT head

›Persistent altered mental status not explained by CO alone

›Focal neurologic deficit

›Trauma after syncope

›CT chest

›Inhalation injury complications concern

›Alternative diagnosis concern

Ultrasound

›POCUS applications

›Cardiac POCUS

›Global function

›Pericardial effusion

›Lung POCUS

›Pulmonary edema

›Alternative diagnosis support

13Special Tests/spec17

Bedside and confirmatory testing

›Diagnostic tests beyond routine labs

›Co oximetry

›Measures COHb and methemoglobin

›Prefer arterial or venous blood over pulse oximetry

›Continuous cardiac monitoring

›Dysrhythmia detection

›Ischemia surveillance

›Neurocognitive screening

›Short memory and attention screen if stable

›Baseline for follow up

Hyperbaric oxygen coordination tests

›Pre transfer requirements local protocol dependent

›Pregnancy testing when applicable

›Urine or serum testing

›Gestational age documentation

›Fire exposure screening

›Lactate in mmol/L

›Consider cyanide evaluation pathway

14ECG/ecg20

Indications and high risk findings

›ECG use

›Indications

›Chest pain

›Dyspnea

›Syncope

›Older adults

›Known coronary disease

›High risk patterns

›ST elevation

›ST depression

›T wave inversion new

›Ventricular dysrhythmia

›QT prolongation

Serial ECG and biomarkers

›Monitoring strategy

›Serial ECG timing

›Repeat with symptom change

›Repeat with abnormal initial ECG

›Troponin strategy

›Serial per local ACS pathway

›Higher concern with CO exposure plus ischemic symptoms

15Assessment/ax21

Working diagnosis and severity

›Carbon monoxide poisoning assessment

›Working diagnosis

›Suspected carbon monoxide poisoning (T58.91XA)

›Confirmed by elevated COHb

›Severity stratification

›Mild symptoms with normal mentation

›Neurologic involvement

›Cardiac involvement

›Severe acidosis

›Complications to rule out

›Myocardial ischemia

›Dysrhythmia

›Inhalation injury

›Cyanide co toxicity with fire exposure

Diagnostic uncertainty

›Alternative diagnoses

›Persistent symptoms despite low COHb after oxygen

›Consider alternate causes of headache

›Consider infection

›No clear exposure source

›Consider medical mimics

›Consider environmental assessment needs

16Plan/plan55

First 5 minutes

›Immediate stabilization workflow

›Monitoring

›Continuous pulse oximetry

›Continuous cardiac monitoring

›Frequent blood pressure cycling

›Oxygen

›High flow oxygen via nonrebreather

›Target SpO2 94 to 98

›IV access

›One large bore IV for stable

›Two large bore IV for unstable

›Point of care tests

›Fingerstick glucose

›ECG if chest pain or syncope

›Escalation triggers

›GCS less than 13

›Seizure

›Shock

›Respiratory failure

Therapeutics

›Treatment priorities

›Normobaric oxygen

›100 percent oxygen until symptoms resolve

›Continue until COHb normalizing with clinical improvement

›Hyperbaric oxygen consultation local protocol dependent

›Loss of consciousness

›Persistent neurologic symptoms

›Ischemic ECG changes or elevated troponin

›Severe acidosis

›Pregnancy with elevated COHb or symptoms

›Fluids

›Isotonic crystalloid bolus for hypotension

›Reassess perfusion after bolus

›Antiemetic example adult dosing

›Ondansetron ODT or IV 4 mg

›Repeat 4 mg once if needed

›Seizure treatment example adult dosing

›Lorazepam IV 2 mg

›Repeat every 2 to 3 minutes to maximum 8 mg

›Cyanide antidote pathway fire exposure local protocol dependent

›Consider hydroxocobalamin when severe lactic acidosis plus fire exposure

›Coordinate with toxicology

Reassessment loop

›Reassessment cadence

›Neuro status

›Repeat mental status every 30 to 60 minutes

›Repeat gait when safe

›Symptom response

›Headache trajectory on oxygen

›Nausea control

›Objective monitoring

›Repeat COHb per clinical course

›Repeat ECG and troponin when indicated

›Disposition pivot triggers

›New neurologic deficit

›Rising troponin

›Persistent symptoms after several hours of oxygen

17Disposition/dispo33

Level of care criteria

›ICU or high acuity criteria

›Airway or ventilation support required

›Intubation

›Noninvasive ventilation

›Hemodynamic instability

›Vasopressor requirement

›Persistent hypotension

›Severe neurologic toxicity

›Coma

›Recurrent seizures

›Cardiac complications

›Ongoing ischemia

›Malignant dysrhythmia

Admission and discharge criteria

›Inpatient or observation criteria

›Persistent symptoms despite oxygen

›Headache not improving

›Ongoing nausea or vomiting

›Abnormal investigations

›Elevated troponin

›Significant acidosis

›Social reliability concerns

›Unsafe return environment

›No reliable supervision

›Discharge criteria

›Clinical stability

›Normal mentation at baseline

›Symptoms resolved or minimal and improving

›Safe environment confirmed

›Source addressed by qualified services

›Functional CO alarms present

›Follow up arranged

›Primary care within 24 to 72 hours

›Neuro follow up if symptoms occurred

18Discharge Instructions/di26

Copy discharge instructions

›Discharge text

›Diagnosis summary

›You were treated for possible carbon monoxide exposure

›Carbon monoxide can cause headache, dizziness, nausea, confusion, and chest pain

›Home safety

›Do not return to the exposure location until it is cleared safe by qualified services

›Ensure working carbon monoxide alarms are installed

›Medications

›Use your usual medications as prescribed

›If nausea returns, use prescribed anti nausea medication as directed

›Activity

›Rest today

›Avoid driving if you feel dizzy or foggy

›Follow up

›Primary care follow up in 1 to 3 days

›If you had confusion or fainting, discuss neuro follow up

›Return to ED now for

›Fainting

›New confusion

›Seizure

›Chest pain

›Shortness of breath

›Worsening headache

›Persistent vomiting

›New weakness or numbness

›Symptoms after returning to the same building

19References/r16

Guidelines and key sources

›Evidence based references

›Undersea and Hyperbaric Medical Society

›Hyperbaric oxygen indications for carbon monoxide poisoning

›Local protocol dependent thresholds

›CDC

›Clinical guidance for carbon monoxide poisoning

›Prevention and public health recommendations

›American Heart Association

›Carbon monoxide and cardiovascular effects

›Ischemia risk considerations

›Goldfrank Toxicologic Emergencies

›Carbon monoxide poisoning management

›Cyanide co toxicity considerations in fire

›Project instructions source

›Formatting requirements

›Structure requirements

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.

Carbon Monoxide ExposureAPPROACH

TOXICOLOGY AND BEHAVIORAL · 19 SECTIONS

⚲

570 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/hx68

Exposure context

›Carbon monoxide exposure context

›Location type

›Home

›Garage

›Workplace

›Vehicle

›Fire or smoke exposure

›Exposure scenario

›Enclosed space

›Multiple people symptomatic

›Pets symptomatic

›Recent use

›Furnace or boiler

›Space heater

›Generator

›Grill or charcoal

›Fireplace

›Gas stove or oven

›Timeline

›Time of last known well

›Estimated duration of exposure

›Time since removal from source

›Prehospital care

›Oxygen given

›Time on oxygen before labs

Symptom characterization

›Symptom profile

›Associated symptoms

›Headache

›Dizziness

›Nausea

›Vomiting

›Weakness

›Chest pain

›Dyspnea

›Confusion

›Syncope

›Seizure

›Symptom trajectory

›Improving after fresh air or oxygen

›Persistent despite oxygen

›Functional impact

›Unable to ambulate normally

›Unable to maintain oral intake

OPQRST if prominent symptom

›OPQRST for dominant symptom

›Onset

›Sudden

›Gradual

›Time of onset relative to exposure

›Provocation or palliation

›Worse in enclosed space

›Better outdoors

›Better with oxygen

›Quality

›Pressure

›Throbbing

›Shortness of breath sensation

›Region or radiation

›Frontal

›Diffuse

›Chest radiation

›Severity

›Mild

›Moderate

›Severe

›Timing

›Constant

›Intermittent

›Recurrent with re exposure

02Alarm Features/alarm28

Immediate life threats

›Critical features

›Airway compromise

›Inability to protect airway

›Recurrent vomiting with somnolence

›Respiratory failure

›SpO2 low on high flow oxygen

›Severe work of breathing

›Neurologic emergency

›Seizure

›Coma

›Focal neurologic deficit

›Cardiovascular emergency

›Chest pain concerning for ischemia

›Dysrhythmia

›Shock

High risk thresholds

›Escalation thresholds

›Systolic blood pressure less than 90 mmHg

›Escalate to resuscitation bay

›Vasopressor consideration after fluids

›Respiratory rate greater than 30

›Noninvasive ventilation consideration

›Early intubation consideration

›GCS less than 13

›Immediate airway readiness

›Immediate hyperbaric consultation consideration

›Persistent altered mental status

›Continuous monitoring

›Broaden differential and co ingestion workup

03Medications/meds28

Current and recent agents

›Medication reconciliation focus

›Cardioactive medications

›Beta blockers

›Calcium channel blockers

›Antiarrhythmics

›Sedatives and opioids

›Benzodiazepines

›Opioids

›Glucose lowering agents

›Insulin

›Sulfonylureas

›Anticoagulants and antiplatelets

›DOACs

›Warfarin

›Aspirin

›Recent changes

›Dose increase

›Missed doses

Treatment relevant contraindications

›Oxygen therapy considerations

›Severe COPD with chronic hypercapnia

›Titrate oxygen with ABG or VBG monitoring

›Ventilatory support thresholds

›Pregnancy status

›Lower threshold for hyperbaric consultation

›Fetal monitoring coordination

›Seizure history

›Hyperbaric seizure risk awareness

›Antiseizure medication adherence

04Diet/diet13

Recent intake and exposures

›Intake and exposure patterns

›Hydration status indicators

›Poor oral intake

›Vomiting limiting intake

›Alcohol exposure

›Recent ethanol intake

›Risk of co intoxication

›Caffeine and energy drinks

›High caffeine intake

›Palpitations confounders

›Carbon monoxide relevant environment

›Recent indoor cooking or heating

›Use of charcoal indoors

05Review of Systems/ros26

System symptom screen

›ROS clusters

›General

›Fatigue

›Malaise

›Fever

›Neurologic

›Headache

›Confusion

›Dizziness

›Visual changes

›Syncope

›Seizure

›Cardiopulmonary

›Chest pain

›Dyspnea

›Palpitations

›Gastrointestinal

›Nausea

›Vomiting

›Abdominal pain

›ENT

›Sore throat after smoke

›Hoarseness

›Dermatologic

›Burns or soot exposure

›Cyanosis

06Collateral History and Family History/chafh20

Collateral and scene information

›Collateral sources

›EMS report

›Scene description

›Other symptomatic occupants

›Fire department

›CO detector readings if available

›Environmental remediation status

›Family or roommates

›Shared symptom pattern

›Timing of symptom onset

Family history relevant to risk

›Family history considerations

›Early coronary artery disease

›First degree relative under 55 male

›First degree relative under 65 female

›Hemoglobinopathies

›Sickle cell disease

›Thalassemia

›Inherited arrhythmia syndromes

›Long QT syndrome

›Brugada syndrome

07Risk Factors/rf27

Exposure and environmental risks

›Exposure risk factors

›Enclosed space exposure

›Poor ventilation

›Sleeping during exposure

›Faulty combustion sources

›Furnace or boiler malfunction

›Generator indoors

›Vehicle running in garage

›Fire and smoke exposure

›Structural fire

›Wildfire smoke in enclosed space

Patient factors increasing harm

›High risk populations

›Pregnancy

›Increased fetal susceptibility

›Lower threshold for hyperbaric consultation

›Infants and children

›Higher minute ventilation

›Nonspecific symptom presentation

›Older adults

›Higher cardiac risk

›Baseline cognitive vulnerability

›Coronary artery disease (I25.10)

›Lower ischemia threshold

›Higher risk dysrhythmia

›Anemia (D64.9)

›Reduced oxygen carrying capacity

›More severe symptoms at lower COHb

08Differential Diagnosis/ddx45

Life threatening

›Life threatening causes

›Carbon monoxide poisoning (T58.91XA)

›Multiple occupants symptomatic

›Improvement with oxygen

›Cyanide toxicity

›Fire in enclosed space

›Severe lactic acidosis

›Acute coronary syndrome (I21.9)

›Chest pain

›ECG ischemia

›Stroke or TIA (I63.9)

›Focal deficits

›Persistent neurologic symptoms

›Severe hypoglycemia (E16.2)

›Diaphoresis

›Altered mental status

›Toxic co ingestion

›Sedative toxidrome

›Opioid toxidrome

Common

›Common alternatives

›Viral syndrome

›Fever

›Myalgias

›Migraine

›Photophobia

›Prior migraine history

›Gastroenteritis

›Diarrhea

›Sick contacts

›Anxiety or panic symptoms

›Hyperventilation

›Paresthesias

Less common

›Less common and mimics

›Methemoglobinemia

›Low SpO2 with normal PaO2

›Oxidant exposure

›Carbon dioxide exposure

›Confined space

›Headache with hypercapnia

›Meningitis or encephalitis (G00.9)

›Neck stiffness

›Persistent altered mental status

›Thyrotoxicosis (E05.90)

›Tremor

›Heat intolerance

09Past Medical History/pmh22

Relevant conditions and baseline

›Baseline risks and prior events

›Prior carbon monoxide exposure

›Prior hyperbaric treatment

›Delayed neuropsychiatric symptoms history

›Cardiopulmonary disease

›Coronary artery disease (I25.10)

›Heart failure (I50.9)

›COPD (J44.9)

›Asthma (J45.909)

›Neurologic disorders

›Seizure disorder (G40.909)

›Stroke history (I63.9)

›Hematologic conditions

›Anemia (D64.9)

›Sickle cell disease (D57.1)

Pregnancy and pediatric specifics

›Special populations baseline

›Pregnancy status

›Gestational age

›Obstetric complications

›Pediatrics

›Developmental baseline

›Baseline feeding pattern

10Physical Exam/exam39

Vitals and general appearance

›Immediate exam targets

›Vitals trends

›Temperature

›Heart rate

›Blood pressure

›Respiratory rate

›SpO2 on room air and on oxygen

›General appearance

›Toxic appearance

›Diaphoresis

›Altered level of consciousness

›Perfusion

›Capillary refill

›Skin temperature

›Peripheral pulses

Neurologic and cardiopulmonary

›System focused findings

›Neurologic

›GCS

›Orientation

›Cranial nerves

›Motor strength

›Sensation

›Coordination

›Gait if safe

›Cardiovascular

›Heart sounds

›Murmur

›Signs of heart failure

›JVP elevation

›Peripheral edema

›Crackles

›Respiratory

›Work of breathing

›Wheeze

›Crackles

›Soot in nares or oropharynx

›Skin

›Burns

›Soot contamination

11Lab Studies/labs34

Core labs and interpretation

›Key laboratory tests

›Carboxyhemoglobin level

›Venous acceptable for COHb trending

›Interpret with time on oxygen

›Blood gas

›ABG or VBG

›PaO2 in mmHg

›pH

›Lactate in mmol/L

›Basic metabolic panel

›Sodium in mmol/L

›Potassium in mmol/L

›Creatinine

›Glucose

›CBC

›Hemoglobin

›Leukocytosis context

›Troponin

›Chest pain

›Abnormal ECG

›Older adults

›CK

›Prolonged immobilization concern

›Seizure concern

Pitfalls and limitations

›Common interpretation pitfalls

›SpO2 limitation

›Pulse oximetry may read falsely normal

›Does not measure COHb

›COHb level limitations

›Lower after oxygen therapy

›Symptoms may not correlate with COHb

›Lactate interpretation

›High lactate suggests severe hypoxia

›Very high lactate in fire suggests cyanide co toxicity

12Imaging/img32

Scoring Systems

›Severity and pathway tools

›Hyperbaric referral triggers local protocol dependent

›Loss of consciousness

›Persistent neurologic symptoms

›Severe metabolic acidosis

›Pregnancy with elevated COHb

›Fire exposure adjunct risk assessment

›Soot in airway

›Facial burns

›Hoarseness or stridor

MRI

›Neuro imaging considerations

›MRI brain for delayed neuropsychiatric syndrome concern

›Cognitive change days to weeks after exposure

›Movement disorder symptoms

›MRI limitations

›Not required for typical acute management

›Timing dependent findings

›CT indications

›CT head

›Persistent altered mental status not explained by CO alone

›Focal neurologic deficit

›Trauma after syncope

›CT chest

›Inhalation injury complications concern

›Alternative diagnosis concern

Ultrasound

›POCUS applications

›Cardiac POCUS

›Global function

›Pericardial effusion

›Lung POCUS

›Pulmonary edema

›Alternative diagnosis support

13Special Tests/spec17

Bedside and confirmatory testing

›Diagnostic tests beyond routine labs

›Co oximetry

›Measures COHb and methemoglobin

›Prefer arterial or venous blood over pulse oximetry

›Continuous cardiac monitoring

›Dysrhythmia detection

›Ischemia surveillance

›Neurocognitive screening

›Short memory and attention screen if stable

›Baseline for follow up

Hyperbaric oxygen coordination tests

›Pre transfer requirements local protocol dependent

›Pregnancy testing when applicable

›Urine or serum testing

›Gestational age documentation

›Fire exposure screening

›Lactate in mmol/L

›Consider cyanide evaluation pathway

14ECG/ecg20

Indications and high risk findings

›ECG use

›Indications

›Chest pain

›Dyspnea

›Syncope

›Older adults

›Known coronary disease

›High risk patterns

›ST elevation

›ST depression

›T wave inversion new

›Ventricular dysrhythmia

›QT prolongation

Serial ECG and biomarkers

›Monitoring strategy

›Serial ECG timing

›Repeat with symptom change

›Repeat with abnormal initial ECG

›Troponin strategy

›Serial per local ACS pathway

›Higher concern with CO exposure plus ischemic symptoms

15Assessment/ax21

Working diagnosis and severity

›Carbon monoxide poisoning assessment

›Working diagnosis

›Suspected carbon monoxide poisoning (T58.91XA)

›Confirmed by elevated COHb

›Severity stratification

›Mild symptoms with normal mentation

›Neurologic involvement

›Cardiac involvement

›Severe acidosis

›Complications to rule out

›Myocardial ischemia

›Dysrhythmia

›Inhalation injury

›Cyanide co toxicity with fire exposure

Diagnostic uncertainty

›Alternative diagnoses

›Persistent symptoms despite low COHb after oxygen

›Consider alternate causes of headache

›Consider infection

›No clear exposure source

›Consider medical mimics

›Consider environmental assessment needs

16Plan/plan55

First 5 minutes

›Immediate stabilization workflow

›Monitoring

›Continuous pulse oximetry

›Continuous cardiac monitoring

›Frequent blood pressure cycling

›Oxygen

›High flow oxygen via nonrebreather

›Target SpO2 94 to 98

›IV access

›One large bore IV for stable

›Two large bore IV for unstable

›Point of care tests

›Fingerstick glucose

›ECG if chest pain or syncope

›Escalation triggers

›GCS less than 13

›Seizure

›Shock

›Respiratory failure

Therapeutics

›Treatment priorities

›Normobaric oxygen

›100 percent oxygen until symptoms resolve

›Continue until COHb normalizing with clinical improvement

›Hyperbaric oxygen consultation local protocol dependent

›Loss of consciousness

›Persistent neurologic symptoms

›Ischemic ECG changes or elevated troponin

›Severe acidosis

›Pregnancy with elevated COHb or symptoms

›Fluids

›Isotonic crystalloid bolus for hypotension

›Reassess perfusion after bolus

›Antiemetic example adult dosing

›Ondansetron ODT or IV 4 mg

›Repeat 4 mg once if needed

›Seizure treatment example adult dosing

›Lorazepam IV 2 mg

›Repeat every 2 to 3 minutes to maximum 8 mg

›Cyanide antidote pathway fire exposure local protocol dependent

›Consider hydroxocobalamin when severe lactic acidosis plus fire exposure

›Coordinate with toxicology

Reassessment loop

›Reassessment cadence

›Neuro status

›Repeat mental status every 30 to 60 minutes

›Repeat gait when safe

›Symptom response

›Headache trajectory on oxygen

›Nausea control

›Objective monitoring

›Repeat COHb per clinical course

›Repeat ECG and troponin when indicated

›Disposition pivot triggers

›New neurologic deficit

›Rising troponin

›Persistent symptoms after several hours of oxygen

17Disposition/dispo33

Level of care criteria

›ICU or high acuity criteria

›Airway or ventilation support required

›Intubation

›Noninvasive ventilation

›Hemodynamic instability

›Vasopressor requirement

›Persistent hypotension

›Severe neurologic toxicity

›Coma

›Recurrent seizures

›Cardiac complications

›Ongoing ischemia

›Malignant dysrhythmia

Admission and discharge criteria

›Inpatient or observation criteria

›Persistent symptoms despite oxygen

›Headache not improving

›Ongoing nausea or vomiting

›Abnormal investigations

›Elevated troponin

›Significant acidosis

›Social reliability concerns

›Unsafe return environment

›No reliable supervision

›Discharge criteria

›Clinical stability

›Normal mentation at baseline

›Symptoms resolved or minimal and improving

›Safe environment confirmed

›Source addressed by qualified services

›Functional CO alarms present

›Follow up arranged

›Primary care within 24 to 72 hours

›Neuro follow up if symptoms occurred

18Discharge Instructions/di26

Copy discharge instructions

›Discharge text

›Diagnosis summary

›You were treated for possible carbon monoxide exposure

›Carbon monoxide can cause headache, dizziness, nausea, confusion, and chest pain

›Home safety

›Do not return to the exposure location until it is cleared safe by qualified services

›Ensure working carbon monoxide alarms are installed

›Medications

›Use your usual medications as prescribed

›If nausea returns, use prescribed anti nausea medication as directed

›Activity

›Rest today

›Avoid driving if you feel dizzy or foggy

›Follow up

›Primary care follow up in 1 to 3 days

›If you had confusion or fainting, discuss neuro follow up

›Return to ED now for

›Fainting

›New confusion

›Seizure

›Chest pain

›Shortness of breath

›Worsening headache

›Persistent vomiting

›New weakness or numbness

›Symptoms after returning to the same building

19References/r16

Guidelines and key sources

›Evidence based references

›Undersea and Hyperbaric Medical Society

›Hyperbaric oxygen indications for carbon monoxide poisoning

›Local protocol dependent thresholds

›CDC

›Clinical guidance for carbon monoxide poisoning

›Prevention and public health recommendations

›American Heart Association

›Carbon monoxide and cardiovascular effects

›Ischemia risk considerations

›Goldfrank Toxicologic Emergencies

›Carbon monoxide poisoning management

›Cyanide co toxicity considerations in fire

›Project instructions source

›Formatting requirements

›Structure requirements

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.