Читать книгу Emergency Medical Services - Группа авторов - Страница 487

Since the patient’s vascular circuit is violated and connected to the outside world during hemodialysis, concern exists for the introduction of air into the patient’s bloodstream. While small amounts of air into the vascular system can be asymptomatic, larger amounts can cause serious sequelae. It is estimated that 3–5 mL/kg of air is the lethal dose [27]. Air traveling through the vasculature toward the brain can cause cerebral blood outflow obstruction, leading to increasing intracranial pressure, altered mental status, and seizures. If air travels into the right side of the heart and migrates to the lung, it can act as a pulmonary embolism and cause dyspnea, chest discomfort, and hemodynamic instability. In rare cases, a heart defect could allow air to pass from the right‐sided circulation into the arterial flow to the body, leading to stroke or myocardial infarction as an arterial gas embolism. A patient with air embolism requires hemodynamic support, high‐flow oxygen, and prevention of further air embolization. The venous line should be clamped, and the blood pump on the dialysis machine should be stopped. Positioning the affected patient in the left lateral recumbent position (right heart up) may help to stabilize trapped air in the right heart, stopping further embolization. Percutaneous aspiration of air from the ventricle in a patient in extremis may be performed by the EMS physician in the field or by qualified staff on arrival to the ED. Hyperbaric oxygen has been established as a treatment modality once the patient is stable enough for therapy [27].