CARBON DIOXIDE, USP
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CARBON DIOXIDE, USP (CARBON DIOXIDE, USP).
Carbon dioxide acts as a respiratory stimulant via central and peripheral chemoreceptors, increases cerebral blood flow through vasodilation, and affects acid-base balance by forming carbonic acid.
| Metabolism | Carbon dioxide is transported in blood as bicarbonate, dissolved CO2, and carbamino compounds. It is eliminated primarily via lungs; small amounts are excreted in urine. |
| Excretion | Carbon dioxide is eliminated almost entirely via the lungs as a gas. In steady state, approximately 60-70% of CO2 is transported as bicarbonate in plasma and rapidly equilibrated with alveolar gas. Renal excretion is negligible (<1%) under normal conditions, as bicarbonate is reabsorbed; however, in metabolic acidosis, renal excretion of H+ and reclamation of bicarbonate can increase, but direct CO2 excretion remains pulmonary. |
| Half-life | The terminal elimination half-life of CO2 is approximately 1-3 minutes, reflecting rapid equilibration with body stores (primarily bicarbonate and carbamino compounds). This short half-life allows for minute-to-minute adjustments by ventilation. Clinically, changes in ventilation lead to new steady-state CO2 levels within 5-10 minutes. |
| Protein binding | Negligible (<1%). CO2 binds reversibly to amino groups of proteins (e.g., hemoglobin) forming carbamino compounds, but this is not classical protein binding and does not affect pharmacokinetic calculations; no specific binding proteins. |
| Volume of Distribution | Approximately 0.5-0.6 L/kg (total body water). CO2 is highly soluble and distributes into all tissues, including intracellular and extracellular compartments. The apparent volume of distribution reflects total body CO2 stores, which are large relative to plasma. |
| Bioavailability | Inhalation: 100% (directly into pulmonary circulation). Intravenous: 100%. Intraperitoneal or subcutaneous: approximately 100% as gas is rapidly absorbed. Oral or gastrointestinal: not applicable as CO2 is not administered orally; if ingested, it is exhaled or eructated. |
| Onset of Action | Inhalation: Immediate (seconds) due to direct absorption across alveolar-capillary membrane. Intravenous: rapid (seconds) when used in diagnostic procedures (e.g., CO2 angiography). Intraperitoneal or subcutaneous: within a few minutes as gas diffuses into blood. |
| Duration of Action | Duration is as long as the gas is present in tissues and ventilation is maintained. For insufflation (e.g., laparoscopy), effects last minutes to hours depending on gas clearance and reabsorption. Clinical effects (e.g., hypercapnia) resolve within 5-10 minutes after removal of inspired CO2 or cessation of insufflation due to rapid pulmonary elimination. |
5% carbon dioxide with 95% oxygen or 10% carbon dioxide with 90% oxygen, inhaled via face mask or ventilator, titrated to achieve arterial pCO2 of 35-45 mmHg; typically 1-2 L/min, adjusted based on clinical response.
| Dosage form | GAS |
| Renal impairment | No dose adjustment required for renal impairment as carbon dioxide is eliminated primarily by ventilation. |
| Liver impairment | No dose adjustment required for hepatic impairment. |
| Pediatric use | Neonates and children: 5% carbon dioxide in oxygen, inhaled at 1-2 L/min, titrated to arterial pCO2 35-45 mmHg; adjust based on clinical and blood gas monitoring. |
| Geriatric use | Use with caution due to age-related decreased pulmonary function; initiate at lowest effective concentration and titrate slowly; monitor arterial blood gases and respiratory status closely. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for CARBON DIOXIDE, USP (CARBON DIOXIDE, USP).
| Breastfeeding | Endogenous CO2 is present in breast milk at low levels; exogenous inhalation resolves rapidly. No data on M/P ratio. Excretion in milk of administered CO2 is negligible due to rapid pulmonary elimination. Generally compatible with breastfeeding if maternal respiratory status is stable. |
| Teratogenic Risk | Carbon dioxide is an endogenous gas in minute quantities; however, administered concentrations exceed physiologic levels. Inhaled CO2 does not have known teratogenic effects from clinical use, but fetal hypoxia/acidosis from maternal hypercapnia in any trimester may cause adverse outcomes. No adequate human studies; animal studies not conducted. Avoid during pregnancy unless clearly necessary. |
■ FDA Black Box Warning
Must be administered by qualified personnel trained in airway management and resuscitation. Rapid insufflation can cause gas embolism, hypotension, and cardiac arrest.
| Serious Effects |
Absolute: Severe hypercapnia, acute respiratory acidosis. Relative: Pregnancy, pre-existing cerebral edema, untreated pneumothorax.
| Precautions | Risk of hypercapnia, acidosis, and gas embolism during insufflation. Avoid extravasation; monitor end-tidal CO2 and vital signs. Use with caution in patients with pulmonary or cardiovascular disease. |
| Food/Dietary | No clinically relevant food interactions. CO2 is a gas used in medical procedures and does not interact with dietary components. |
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| Fetal Monitoring | Monitor maternal arterial blood gases (PaCO2, pH), oxygen saturation, and respiratory rate. Fetal heart rate monitoring if maternal hypercapnia develops. Assess for signs of respiratory acidosis and cerebral vasodilation. |
| Fertility Effects | No known effect on fertility from inhaled CO2 at therapeutic doses. No data on reproductive toxicity. |
| Clinical Pearls | Carbon dioxide (CO2) is used in medical settings for insufflation during laparoscopic surgery, as a respiratory stimulant in the form of carbogen (5-10% CO2 with oxygen), and for cryotherapy. Monitor for hypercapnia when used as insufflation gas. In diagnostic procedures, CO2 is superior to air for safe contrast in radiology. Avoid in patients with compromised lung function due to risk of CO2 retention. |
| Patient Advice | Explain that CO2 is used to inflate the abdomen during surgery to improve visualization. · Inform patients that they may experience shoulder pain after laparoscopy due to CO2 irritation of the diaphragm. · Advise that cryotherapy with CO2 may cause temporary discomfort and blistering. · For carbogen therapy, discuss potential dizziness or shortness of breath. |