<prompt> Oxygen therapy is most useful inArterial hypoxiaStagnent hypoxiaAnemic hypoxiaCyanide hypoxia  <response>: Arterial hypoxia 75-77-A yadav 4thHypoxic hypoxia responds best to oxygen therapy while there is no benefit to oxygen therapy in histotoxic cyanoidpoisoning hypoxiaClinical presentation of hypoxia is cyanosis, which is produced if reduced Hb level is more than 5gdl which roughly corresponds to O2 saturation 85 to 90 or pO2 50 mmHg methaemoglobin 1.5gdL and sulphaemoglobin 0.5 gdLCharacteristic features of diffeent types of HvpoxiaFeaturesHypoxic hypoxiaAnemic hypoxiaStagnant hypoxiaHistotoxic hypoxia1. CO2 in arterial bloodReducedNormalNormalNormal2. O2 carrying capacity of bloodNormalReducedNormalNormal3. Rate of blood flowNormalNormalReducedNormal4. Utilization of O2 by tissue1007550Not usefulOXYGEN TOXICITY - toxic radicals of oxygen damage the capillary membrane increasing capillary permeability and ARDS like picture, Abnormality in ciliary transport, absorption atelectasis and tracheobronchitis, decreased pulmonary complianceIn neonates pulmonary toxicity manifests as bronchopulmonary dysplasia, Retrolental fibroplasia premature neonates 36 weeks are greatest risk. Acute oxygen toxicity may manifest as convulsions this is called as paulbert effectHYPER BARIC OXYGEN : USESA.Poisonings- CO, cyanoid poisoningB.Gas bubble disease- Decompression sickness, Air embolismC.Ischaemia- Crush injury, Ischemic ulcer, Radiation necrosisD.Infections- Clostridial, Mucormycosis, Refractory osteomyelitisE.Others- Oxygen support during lung lavage, Bums cerebral edemaHeliox 80 helium 20 oxygen is used for upper air way obstruction like tracheal stenosis 