INTRODUCTION: Pulmonary Embolism (PE) affects 0.5%-1 per 1000 people in the general population and the commonest cause of death among hospital inpatients. Intraoperative PE are relatively uncommon, but may occur with specific surgeries such as long bone fractures and tumor surgeries. Clinical presentation is usually sudden with cardiovascular collapse and death. In acute massive PE, 50% of the patient will die within 15 minutes and only 33 % will survive over 2 hours.
CASE PRESENTATION: A 44-year-old Male patient presented with a right ankle fracture. He was scheduled for open reduction and internal fixation. Past medical history was negative. He smoked, drank alcohol and used cocaine. He is 110 kg, height of 190 cm. Patient underwent general anesthesia for the surgery. He was placed on mechanical ventilation to maintain end tidal carbon dioxide tension (ETCO2) between 30 to 35 mmHg. Vital signs remained stable until 60 minutes after induction, following positioning in the left lateral decubitus postion, it was noted that the ETCO2 was 17 mmHg. Pulse oximeter saturation (SPO2) ranging from 95 to 100%. Vital signs remained stable. An immediate search for the cause was undertaken. Auscultation of the chest showed vesicular breath sounds. The breathing circuit did not reveal any leaks or disconnects. Bronchoscopy also showed the endotracheal tube to be in proper position. A possible diagnosis of pulmonary embolism was made and an ABG was sent for analysis. ABG showed respiratory acidosis with a pH of 7.21, pCO2 of 76, with an ETCO2 of 17. The surgeon was notified and surgery was expedited. Patient was kept intubated. Spiral chest CT which showed a pulmonary embolus involving the right main pulmonary artery.The patient was transferred to the ICU where he was started on enoxaparin 1 mg per kg q 12 hours. He also had an IVC filter placed. He made a slow but gradually recovery and was discharged home 2 weeks later.
DISCUSSIONS: As early as 1856, Rudolf Virchow defined vascular thrombosis and its triad –alteration of vessels, alteration of blood elements, and alteration of blood flow are the leading causes of venous thrombosis with subsequent pulmonary embolism.Risks factors include age > 40, varices in the lower limbs, previous DVT, major surgery, neoplasia, obesity, previous MI, CHF, use of estrogen, sepsis. The only risk factor that this patient had is age over 40 and obesity.PE may present in the awake patient with respiratory distress, hypoxia, hemoptysis, pleuritic pain, pleural effusion or shock. In anesthetized patient, initial presentation is usually cardiovascular collapse, however, in our patient, the presentation was decreased ETCO2 with minimal changes in vital signs except for slight reduction in oxygen saturation. Intraoperative decrease in ETCO2 is usually due to hyperventilation, bronchospasm, partial circuit disconnect or decreased cardiac output. Diagnosis can be verified by arterial blood gases (ABG) which showed metabolic acidosis with widened CO2 gradient secondary to massive increase in dead space. The gold standard for the definitive diagnosis of PE is the CT angiogram. Spiral CT may also show the embolus. Other test include duplex ultrasound of the lower extremities which if positive is highly suggestive of PE. D-dimer can be elevated as well.
CONCLUSION: Intraoperative pulmonary embolism if not massive maybe difficult to diagnose like in this case where the only positive finding was a decrease in ETCO2 with increase in PCO2 ETCO2 gradient. ABG should be one of the first line investigations to be performed anytime there is a low ETCO2 after other causes of decrease ETCO2 are ruled out.
DISCLOSURE: Adejare Windokun, None.