O2 Delivery & HBOT
The immediate, first-line oxygen delivery device indicated for suspected CO poisoning that provides high FiO2 via a reservoir and one-way valves.
What is a 100% oxygen non-rebreather facemask (NRB)?
While frequently cited in classical medical textbooks, this skin finding in CO poisoning is actually rare in living patients and mostly seen postmortem.
What is cherry-red skin (or bullous skin lesions)?
Carbon monoxide binds to hemoglobin with an affinity approximately this many times greater than oxygen.
What is ~240 times (or ~200–240×)?
At the mitochondrial inner membrane, CO directly shuts down aerobic ATP production and halts the electron transport chain by inhibiting this specific enzyme (Complex IV).
What is cytochrome c oxidase?
This specific physiological term describes a deficiency in oxygen delivery or utilization at the cellular/tissue level (as seen in CO toxicity), distinguishing it from a decreased partial pressure of oxygen dissolved in arterial blood PaO2 and from inadequate blood flow/perfusion.
What is tissue hypoxia?
Key distinction
Hypoxia = inadequate tissue oxygenation;
Hypoxemia = low PaO2 in blood;
Ischemia = insufficient vascular perfusion
Breathing 100% O2 on a non-rebreather reduces the half-life of carboxyhemoglobin from ~300 minutes on room air down to this approximate timeframe.
What is ~60 to 90 minutes?
The most common early, nonspecific symptoms reported by patients presenting with mild to moderate CO exposure.
What are headache, dizziness, nausea/vomiting, and fatigue?
CO binding to one heme group stabilizes the relaxed (R) state, causing this direction of shift on the oxyhemoglobin dissociation curve and impairing tissue offloading.
What is a shift to the left?
In addition to hemoglobin, CO binds avidly to this intracellular heme protein in striated muscle, causing direct myocardial depression and skeletal muscle dysfunction.
What is myoglobin?
The primary clinical discharge criteria and home prevention counseling mandatory for all CO poisoning patients before leaving the hospital.
What are complete symptom resolution (with normal ambulation/neuro exam) and the mandatory installation/verification of functional home CO detectors?
Hyperbaric oxygen therapy (HBOT) delivers 100 O2 under 2.5-3.0 ATA, dramatically increasing oxygen dissolved in plasma based on this gas law.
What is Henry's Law?
This key physical exam triage score evaluates eye, verbal, and motor responses (3-15) to detect acute cerebral hypoxia and severe neurological depression.
What is the Glasgow Coma Scale (GCS)?
Unlike CO, these four classic physiological factors shift the oxygen-hemoglobin dissociation curve to the right, facilitating oxygen unloading in working tissues.
What are increased carbon dioxide, decreased pH, increased temperature, and increased 2,3-BPG (or 2,3-DPG)?
The specific cellular and metabolic reason why acute CO toxicity results in a severe high-anion-gap metabolic acidosis.
What is cellular hypoxia / inhibition of oxidative phosphorylation driving anaerobic glycolysis and excess lactic acid production?
When an acutely poisoned CO patient presents with a Glasgow Coma Scale (GCS) score < 15, confusion, or encephalopathy, emergency life-saving interventions (such as endotracheal intubation or HBOT) can proceed without standard written authorization under this legal and ethical doctrine.
What is implied consent (the emergency doctrine / emergency exception to informed consent)?
A carboxyhemoglobin level above 25% in general adults, or above this lower percentage threshold in pregnant patients, serves as a classic indication for HBOT.
What is 15% (due to fetal hemoglobin's higher affinity for CO and prolonged fetal half-life)?
In a fire victim presenting with severe lactic acidosis and elevated carboxyhemoglobin, this concomitant toxic gas poisoning must be suspected and empirically treated.
What is cyanide poisoning?
In acute CO poisoning, standard arterial blood gas values for PaO2 and calculated SaO2 appear normal, but this critical physiological measure of total oxygen carrying capacity is severely decreased.
What is total oxygen content CaO2?
The classic bilateral, symmetric basal ganglia lesion characteristically seen on brain MRI/CT following severe CO-induced hypoxic encephalopathy.
What is necrosis / hyperintensity of the globus pallidus?
At the cellular level, acute hypoxic myocardial injury alters mechanical and electrical cardiac function through these two distinct phenomena: decreased intracellular ATP leading to systolic dysfunction/transient cardiac dilation, and impaired ion pump (Na+/K+ ATPase) activity leading to this major ECG risk.
What are acute cardiac dysrhythmias (or ventricular arrhythmias / conduction blocks)?
Mechanical failure = transient ventricular dilation/hypokinesis due to ATP depletion;
Electrical failure = arrhythmias/ST-T changes due to ion gradient collapse.)
This minor surgical otologic procedure is indicated prior to HBOT chamber descent in intubated or comatose patients unable to perform the Valsalva maneuver to prevent middle ear barotrauma.
What is a prophylactic myringotomy (or tympanostomy tube placement)?
Prolonged low-level exposure in chronic CO toxicity stimulates renal erythropoietin release, leading to this distinct hematologic laboratory finding.
What is secondary polycythemia (or erythrocytosis)?
Unlike nitrous oxide, which is perfusion-limited, the alveolar-capillary transfer of carbon monoxide is classified as this type of transport limitation because it binds avidly to hemoglobin without rapidly raising partial pressure in the capillary.
What is diffusion-limited transport?
Acute CO-induced cardiac injury causes transient ST-segment depressions, T-wave inversions, and elevated troponin via this specific pathophysiological mechanism rather than plaque rupture (Type 1 MI).
What is Type 2 Myocardial Infarction / subendocardial supply-demand mismatch ischemia?
The term for the dreaded complication occurring days to weeks after apparent recovery from acute CO poisoning, manifesting as cognitive decline, parkinsonism, memory loss, and personality changes.
What is Delayed Neurological Sequelae (DNS / Delayed Post-Hypoxic Encephalopathy)?