Young, postpartum woman transported to emergency room in full cardiorespiratory arrest.
Cause of Death • Venous air embolism. • Due to vaginal insufflation. • Other significant conditions: • Postpartum subinvolution of uterus.
Embolism: an obstruction in a blood vessel due to a blood clot or foreign material which occludes the vessel after traveling through the blood stream.
Types of emboli • Thromboemboli • Fat • Air • Tumor • Bullets
Venous Air Emboli • Air/gas introduced into systemic venous circulation. • Many cases are probably subclinical and resolve without significant consequences.
Required Conditions • Direct communication between the source of air and vasculature. • Pressure gradient favoring the passage of gas into the venous circulation.
Important Factors • Amount of air introduced into the venous circulation. • Rate of accumulation of air in venous circulation. • Position of patient.
Quantity of Gas • Small amounts of air are broken up and reabsorbed in the capillary beds. • 100 to 200 ml have been reported in the literature as potentially fatal. • > 5 ml/kg. • Significant symptoms have been reported with as little as 20 ml of air (length unprimed IV tubing). • 2-3 ml into cerebral circulation can be fatal. • 0.5 ml into the LAD can cause ventricular fibrillation.
Rate of Air Infusion • Rapid infusion of air overwhelms the capacity of the capillaries and leads to right ventricular strain with outflow obstruction, increased pulmonary artery pressure and ultimately cardiovascular failure.
Frequency • True incidence is unknown. • Radiologic literature reports 0.13% during insertion and removal of central venous catheters with optimal technique. • 1/47 to 1/3000 of CVC. • 10-50% of high risk neurosurgical procedures.
Morbidity and Mortality • Dependent on multiple factors: • Amount and rate of air infusion. • Other associated conditions.
Causes • Surgical procedures: • Neurosurgical procedures especially with patient in sitting position or with open dural sinuses. • Trauma surgery with compromised large vessels. • Tumors with high vascularity.
Causes • OB-GYN procedures. • Central venous catheters: • Central lines. pulmonary catheters, hemodialysis catheters, Hickman lines, etc. • Mechanical insufflation: • Orogenital sexual activity. • Inadvertent injection of air with IV contrast or other radiologic studies.
Diagnosis • Must have a high suspicion as clinical symptoms can be non-specific or mimic other conditions.
History • Recent surgical procedures. • Blunt or penetrating trauma of head, neck, chest or abdomen • Central venous catheterization. • Peripostpartum oral genital sexual activity.
Clinical Symptoms • Will be dependent on the amount of air and rate of effusion. • Position of patient (sitting versus recumbent). • Paradoxical arterial embolism.
Presentation • Symptoms include shortness of breath, cough, nausea, chest pain, agitation (impending doom) and disorientation. • Cardiovascular findings: • dysrhythmias, hypotension, pulmonary hypertension, myocardial ischemia, increased central venous pressure, “mill wheel murmur”, nonspecific ECG findings (ST segment and T wave changes), shock.
Presentation • Pulmonary findings: • Abnormal breath sounds (rales and wheezing), tachypnea, hemoptysis, cyanosis, decreased arterial oxygen saturation, elevated CO2, increased pulmonary artery pressures, pulmonary edema.
Presentation • Neurologic: • Altered mental status, seizures, focal deficits, loss of consciousness, coma. • Ophthalmologic: • Air bubbles in retinal vessels • Skin: • Crepitus over superficial vessels.
Differential Diagnosis • Extensive and can include coronary artery syndrome, aortic stenosis, atrial fibrillation, bronchospasm, COPD, CHF, aortic dissection, CVA, metabolic disorders, pulmonary emboli and shock from multiple causes.
Diagnostic Studies • Laboratory: • No specific tests. • Blood gas. • Specific tests may be useful for assessing organ damage.
Diagnostic Studies • Imaging studies: • Transesophageal echocardiography. • High sensitivity for detecting air in right ventricle and outflow tract. • Precordial Doppler ultrasound. • Chest x-ray. • CT scan.
Diagnostic Studies • ECG • Non-specific findings (right ventricular strain, increased heart rate, ST depression). • Pulse oximetry • Central venous catheter aspiration.
Management • Transport patient in left lateral decubitus position. • Stop any procedure immediately. • Can attempt to remove air via catheter. • Provide hemodynamic support. • 100% oxygen/intubation. • Maintain volume. • Vasopressors and mechanical ventilation. • Consider hyperbaric oxygen therapy if neurologic symptoms or cardiac instability