[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Medical gases](https://durgical.com/en/pharmacology/classes/medical-gases/) › Oxygen [Pharmacology](https://durgical.com/en/pharmacology/) · [Medical gases](https://durgical.com/en/pharmacology/classes/medical-gases/) # Oxygen Essential medical gas that corrects hypoxaemia. It is adjusted to a saturation target: too much harms the lung and the preterm retina. Updated 2026-11-01 - Class: [Medical gases](https://durgical.com/en/pharmacology/classes/medical-gases/) - Target: Haemoglobin (transport) and cytochrome c oxidase (use in mitochondria) - ATC code: V03AN01 - WHO Model List of Essential Medicines Also called: Medical oxygen, O2 ## Mechanism of action Raising the inspired oxygen fraction raises its partial pressure in the alveolus and arterial blood; haemoglobin becomes more saturated and carries more oxygen to the tissues, where mitochondrial cytochrome c oxidase uses it as the final electron acceptor to make ATP. In a hyperbaric chamber much more oxygen dissolves in plasma and carbon monoxide leaves haemoglobin faster. - Alveolar oxygen partial pressure rises - Haemoglobin saturation increases - More oxygen reaches the tissues - Mitochondria use it to make ATP ## Pharmacokinetics **Absorption** By diffusion from the alveolus; depends on ventilation and gas exchange. **Distribution** Bound to haemoglobin, with a small part dissolved in plasma (much more under hyperbaric conditions). **Elimination** Consumed in metabolism and eliminated as CO2 and water. ## Indications - Hypoxaemia in COPD, including long-term home oxygen [Chronic obstructive pulmonary disease (COPD) →](https://durgical.com/en/conditions/chronic-obstructive-pulmonary-disease/) - Acute hypoxaemia from pneumonia, severe asthma attacks or other causes of respiratory failure [Acute respiratory failure (hypoxaemic and hypercapnic) →](https://durgical.com/en/conditions/acute-respiratory-failure/) - Carbon monoxide poisoning, including hyperbaric therapy [Carbon monoxide poisoning →](https://durgical.com/en/conditions/carbon-monoxide-poisoning/) - Decompression sickness and gas embolism (hyperbaric therapy) [Decompression sickness and diving injuries →](https://durgical.com/en/conditions/decompression-sickness-and-diving-injuries/) - Anaesthesia and resuscitation, and when nitrous oxide is stopped ## Adverse effects ### Common - Dry or bloody nose - Irritation of mucosa and eyes with dry gas - Tiredness and morning headache (home oxygen) ### Serious (rare, important) - Lung toxicity with prolonged high concentrations - Absorption atelectasis - Retinopathy of prematurity - Fire and burns in oxygen-rich atmospheres - Injury from a cylinder that falls or breaks ## Contraindications - No absolute contraindications when there is hypoxaemia; excess without need is avoided ## Key interactions **Opioids, sedatives and anaesthetics** They depress ventilation: on oxygen, saturation can look fine while CO2 rises, so breathing is watched too. ## What is monitored - Pulse oximetry saturation against a defined target - Arterial blood gases when hypercapnia is a risk - Respiratory rate and level of consciousness - In preterm infants: tight saturation control and retinopathy screening ## Administration and safety - Prescribed with a device (cannula, mask) and a saturation target; adjusted to the response. - Humidify oxygen when given for long periods. - Use only equipment cleaned for oxygen service and regulators designed for oxygen. - Cylinders secured and upright, away from flames and heat sources. ## Nursing care - Assess saturation, respiratory rate, work of breathing and mental state. - Teach the patient and family not to smoke or light flames or flammable materials nearby. - Check the skin under the cannula or mask (ears, nose) and the humidification. - Report if saturation does not reach the target or drowsiness appears. ## Pregnancy and breastfeeding Used when there is maternal hypoxaemia, which also puts the fetus at risk. ## Memory aid Oxygen: «not too little, not too much, on target»; and where there is oxygen, no fire and no cigarette. ## Test yourself Think of the answer, then tap the question to see it. ## Which eye complication is linked to excess oxygen in the preterm newborn? Retinopathy of prematurity, from abnormal vascularisation of the immature retina. ## What is absorption atelectasis? The collapse of poorly ventilated alveoli when concentrated oxygen replaces nitrogen, which is poorly soluble and keeps alveoli open; the oxygen is absorbed and the alveolus empties. ## Why does hyperbaric oxygen help in carbon monoxide poisoning? It greatly increases the oxygen dissolved in plasma and speeds the release of CO from haemoglobin. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/oxygen/) ## Related drugs - [Nitrous oxide](https://durgical.com/en/pharmacology/nitrous-oxide/) ## Related conditions - [Chronic obstructive pulmonary disease (COPD)](https://durgical.com/en/conditions/chronic-obstructive-pulmonary-disease/) - [Acute respiratory failure (hypoxaemic and hypercapnic)](https://durgical.com/en/conditions/acute-respiratory-failure/) - [Carbon monoxide poisoning](https://durgical.com/en/conditions/carbon-monoxide-poisoning/) - [Decompression sickness and diving injuries](https://durgical.com/en/conditions/decompression-sickness-and-diving-injuries/) [← Back to the class: Medical gases](https://durgical.com/en/pharmacology/classes/medical-gases/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [Oxygen Therapy | Hyperbaric Oxygen Therapy | MedlinePlus](https://medlineplus.gov/oxygentherapy.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [DailyMed - OXYGEN gas](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=24735481-2ed8-450a-ba24-ba4fc42a8c3e) (DailyMed (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 24 (McGraw Hill, 2023); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=V03AN01) (WHO Collaborating Centre for Drug Statistics Methodology, 2026). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/oxygen/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/oxygen/