Hyperbaric oxygenation in fluid microembolism.

Because clinicians require objectively demonstrable neurological deficits to confirm a diagnosis, the recognition of embolic events in the nervous system is generally restricted to the effects of ischemic necrosis produced by arterial occlusion. However, magnetic resonance imaging (MRI) has shown that lesser degrees of damage associated with small emboli are common, especially in the mid brain, and are usually clinically silent. They are frequently associated with atheromatous embolism in the elderly, but microembolic debris, such as fat, is common in the systemic venous return of healthy people and generally trapped in the microcirculation of the lung being removed by phagocytosis. However, pulmonary filtration may fail and microemboli may also pass through an atrial septal defect in so-called 'paradoxical' embolism. Studies of bubbles formed on decompression in diving have demonstrated the importance of pulmonary filtration in the protection of the nervous system and that filtration is size dependant, as small bubbles may escape entrapment. Fluid and even small solid emboli, arresting in or passing through the cerebral circulation, do not cause infarction, but disturb the blood-brain barrier inducing what has been termed the 'perivenous syndrome'. The nutrition of areas of the white matter of both the cerebral medulla and the spinal cord depends on long draining veins which have been shown to have surrounding capillary free zones. Because of the high oxygen extraction in the microcirculation of the gray matter of the central nervous system, the venous blood has low oxygen content. When this is reduced further by embolic events, tissue oxygenation may fall to critically low levels, leading to blood-brain barrier dysfunction, inflammation, demyelination and eventually, axonal damage. These are the hallmarks of the early lesions of multiple sclerosis where MR spectroscopy has also shown the presence of lactic acid. Significant elevation of the venous oxygen tension requires oxygen to be provided under hyperbaric conditions. Arterial tension is typically increased ten-fold breathing oxygen at 2 atmospheres absolute (ATA), but this results in only a 1.5-fold increase in the cerebral venous oxygen tension. The treatment of decompression sickness, and both animal and clinical studies, have confirmed the value of oxygen provided under hyperbaric conditions in the restoration and preservation of neurological function in the 'perivenous' syndrome.

[Fat embolism after intrapenile injection of sweet almond oil]. / Embolie graisseuse après injection intrapénienne d'huile d'amande douce.

We report a case of fat embolism following self injection of vegetable oil in the penis, to treat an impotence. The patient developed respiratory failure and neurological disorders as confusion. A chest roentgenogram revealed diffuse alveolar infiltrate. Initially, he presented an hemoconcentration, and fat globules in his urine. The outcome was favourable in 72 hours, with oxygen and hydration. The diagnosis of fat embolism was made after neurological improvement: the patient admitted to injection his penis with vegetable oil, in his corpus cavernosum.

[The effect of high-frequency ventilation of the lungs on the pulmonary and systemic circulations in microembolism of the pulmonary artery]. / Vliianie vysokochastotnoi ventiliatsii legkikh na legochnoe i sistemnoe krovoobrashchenie pri mikroémbolii legochnoi arterii.

The linear and volumetric blood flow velocity in the ascending aorta and pulmonary artery conus, right-left ventricular ejection balance, pulmonary and femoral arterial blood pressures, pulmonary microcirculation in fat pulmonary microembolism induced during the routine and high-frequency jet lung ventilation (HFJLV) were studied by ultrasonic techniques in acute experiments on cats with open chest under nembutal narcosis. Pulmonary microembolism was shown to resulted in 487 and 252% increases in pulmonary vascular resistance during the routine and HFJLVs, respectively. There were also 167 and 127% increases in mean pulmonary pressure and 60 and 34% decreases in the volumetric velocity of pulmonary blood flow. The linear velocity of pulmonary blood flow was unchanged with routine lung ventilation, whereas it decreased by 68% with HFJLV. Microembolism impaired the balance between right and left ventricular ejections with blood being redistributed into the greater circulation. The imbalance lasted 5-7 min during HFJLV, while with the routine lung ventilation it was preserved up to the end of the experiment, and systemic blood pressure and total peripheral vascular resistance decreased. Alveolar edema developed in interstitial pulmonary edema. The animals' death occurred 40-60 min later.

Fat embolism: a rational approach to treatment.

Fat embolism following major trauma may be associated with a clinical syndrome with widespread pulmonary and systemic manifestations, the most serious being profound hypoxia with secondary atelectasis, pulmonary edema and pulmonary hypertension, and cerebral depression. Though the origin of the embolic fat is debated, there is evidence to support its origin from both the bone marrow and intravascular chylomicron coalescence.The clinical manifestations are largely explained by a prime assault upon the lung parenchyma and alteration in platelet characteristics.Early recognition and treatment of the condition is essential, adequate oxygenation being of prime importance. Steroids and heparin have been found to be of benefit.