Makindo Medical Notes.com

Position patient head down, left side down which helps keep air in apex of right ventricle where slow reabsorption occurs

About

• Air enters the venous circulation and passes into the systemic circulation
• Depending on volume may result in vascular occlusion and sudden death
• Also depends on the position of the patient such that

Pathophysiology

• A venous point of air entry with a pressure gradient to facilitate air entry
• Any operative procedure where the site is > 5 cm above the right atrium

Causes

• Operative procedures involving major veins or cardiopulmonary bypass
• Surgical procedures e.g. neurosurgery where patients sit upright
• Air embolism in trauma (penetrating lung injury) is usually lethal
• Back Street abortion - air accidentally injected into pelvic venous plexuses
• Carbon dioxide embolus from laparoscopic insufflation
• Can occur with right to left shunt (VSD, etc.)
• Source of air usually massive

Clinical

• Cardiac arrest
• Dyspnoea, Chest pain, Agitation, disorientation, shock

Investigations

• ABG - hypoxia, hypo/hypercarbia, metabolic acidosis
• ECG - tachycardia ST/ T changes of ischaemia
• CXR - oligaemia

Differential

• Pulmonary embolus
• Stroke, MI, Tension PTX
• Traumatic cardiac tamponade

Complications

• Cardiac arrest and death from obstructive shock
• Myocardial Infarction due to air embolus entering coronary artery
• Anoxic brain injury secondary to prolonged cerebral hypoperfusion

Management

• ABC, O₂. Position patient head down, left side down which helps keep air in apex of right ventricle where slow reabsorption occurs. Clamp or remove any central line that is the entry point and flush all lines
• Put patient head down and left lateral decubitus to trap the air in the ventricle
• Intubate and ventilate. Volume + pressors.
• Give 100% O₂ and IV Fluid resuscitation and inotropes
• Other possibilities
  • If venous lines are in RA or RV, aspirate out the air from the RV
  • If chest is open, aspirate RV apex with needle after positioning 
  • If chest is open, cardiac massage to relieve RV outflow obstruction

References