A fatal case of pulmonary embolism after lumbar spine surgery

Sir,

We report a case of a 60-year-old, 75 kg female patient who presented with chief complaints of lower limb weakness with low backache for 2 years. She was diagnosed to have L4–L5 spondylolisthesis with L5-S1 intervertebral disc prolapse and was electively posted for discectomy and laminectomy, with instrumentation of the lumbar spine in prone position (posterior approach). On neurologic examination, her lower limb power was 3/5 bilaterally, with normal tone and bulk. Intraoperative course was uneventful, except for prolonged duration of surgery (8 h) and blood loss of 800 ml. At the end of surgery, patient's residual neuromuscular block was reversed, and her trachea was extubated when she was fully awake and responding to commands. After unremarkable preliminary neurological examination, she was shifted to the Intensive Care Unit (ICU) for observation. Post-operatively, in the ICU, she became drowsy and lethargic with tachypnoea (40/min) within 1 h. Arterial blood gas analysis revealed PaO₂ of 36 mmHg, PaCO₂ 45 mmHg, SaO₂ 73%; troponin I card test was found to be negative. Electrocardiogram showed global ST segment depression with S1Q3T3 pattern [Figure 1]. Immediate post-operative chest X-ray was within normal limits. Pulmonary thromboembolism (PTE) was suspected, and bedside transthoracic two-dimensional echocardiogram revealed right ventricular hypokinesia with dilatation with normal left ventricular function. Computed tomography angiography of the chest revealed a clot in the left main pulmonary artery, occluding nearly 50% of the lumen with smaller clots visible in inferior branch of the right pulmonary artery [Figure 2a and b]. After excluding other differential diagnoses and confirmation of pulmonary embolism (PE) diagnosis, the patient was administered streptokinase 250,000 units over 30 min, followed by 100,000 units/h infusion for next 12 h. However, catheter-directed thrombolysis was not done due to unavailability of logistic support in emergency night hours. Within 2 h, serial blood gases revealed elevated lactate levels along with rise in PaCO₂ levels despite aggressive fluid resuscitation and readjustment of ventilator settings. D-dimer values were found to be more than 2000 μg/L. Later on, she developed severe bradycardia (35/min) and hypotension (60/40 mmHg) and also desaturated to SpO₂ 75% within minutes despite high-flow oxygen through Venturi mask. Cardio-pulmonary resuscitation was started, and after one cycle of continuous compressions, trachea was immediately re-intubated and mechanical ventilation initiated. She was started on noradrenaline (20 µg/min) and dopamine (20 µg/kg/min) infusions through central venous access; however, hypotension persisted despite these measures. The patient progressively deteriorated within 2 h, and serial blood gases revealed elevated lactate levels along with rise in PaCO₂ levels despite aggressive fluid resuscitation and readjustment of ventilator settings. She again suffered a sudden cardiac arrest, from which she could not be revived.

Figure 1.

Electrocardiogram showing global ST segment depression with right ventricular strain (S1Q3T3) pattern

Figure 2.

(a and b) Computed tomography angiograms of chest showing major blockade of left pulmonary artery (small arrow) with the thrombi in situ

Thromboembolic complications are not uncommon following major spine surgeries, predominantly after instrumentation or fixation of the cervical or thoracolumbar spine.[1,2] The maximum incidence of PE is reported in anterior or combined thoracolumbar/lumbar procedures (4.2%).[3] Although deep vein thrombosis (DVT) has been studied extensively in the context of spinal surgery, symptomatic PE might have got less attention possibly because of its rare occurrence in clinical aspects. In this presented case, patient had low-risk scores for PE suspicion. Spine surgery patients are at additional risk for DVT/PTE because of prolonged periods of forced recumbency pre-operatively secondary to neurological deficit or pain and limited mobility after surgery; this results in stasis that plays a pivotal role in the development of venous thrombi.[2] Additional precipitating factors during spine surgery include lengthy operative times in complex surgeries, compression of the femoral venous system by certain frames during prone positioning for posterior approaches to the spine and manipulation of the great vessels during anterior and lateral approaches to the spine.[4] However, anterior approaches are associated with increased risk of PTE than posterior one.[4]

If not diagnosed and treated in an expeditious manner, a PTE can be a fatal condition. Therefore, we reiterate the importance of pre-operative screening and workup for at-risk patients of DVT or PTE. Furthermore, early thromboprophylaxis in post-operative period of high-risk patients and prompt intervention (anticoagulation) or extracorporeal membrane oxygenation are warranted in confirmed and resistant cases of PTE.

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