Diagnosing Pneumothorax with Bedside Ultrasound in a Neonate Post-cardiac Surgery

THE CASE VIGNETTE

A 1-month-old baby weighing 3 kg diagnosed with congenital cyanotic heart disease, Tetralogy of Fallot, reduced pulmonary blood flow, long segment pulmonary atresia, and left pulmonary artery stenosis at origin. The child underwent right modified Blalock-Taussig shunt using 3.5 mm PTFE graft. Postoperatively, the patient developed features of shunt overflow with interstitial edema and third spacing with generalized anasarca requiring diuretics. Longer endotracheal intubation and invasive mechanical ventilation landed the Patient in sepsis with respiratory secretions yielding multidrug resistant acinetobacter. Patient was treated with colistin and tigecycline. Patient had extubation failure twice; hence, surgical tracheostomy was performed with 3.5 mm cuffed tracheostomy tube. Post-tracheostomy auscultation revealed reduced air entry in the right side of the chest, the infant remained stable hemodynamically and SpO₂ read 84%, his arterial blood gas analysis showed severe respiratory acidosis with PH: 6.87, PO_2: 64.3 and PCO_2: 103.5.

Pneumothorax was suspected in view of reduced air entry in right side and high CO₂ and call sent for urgent chest X-ray. In mean time, lung ultrasound was done with conventional adult linear adult probe (6–13 Hz, Sonosite, Fujifilm) which showed the lung point shifted posteriorly and in M mode Stratosphere sign changing into Barcode sign at the level of lung point [Figure 1]. Pneumothorax was diagnosed and arrangements were done for intercostals drain (ICD) insertion. ICD was inserted in the fourth right intercostal space in midaxillary line and pneumothorax was decompressed. Clinically, air entry to right lung and arterial blood gas improved, respiratory acidosis resolved. Chest X-ray done just before ICD insertion showed a large pneumothorax (15 min later when film was collected) in the right side with mediastinal shift [Figure 2].

Close

Figure 1:

Lung ultrasound, M-mode. The blue arrow head shows lung point and here the stratosphere sign changes to Barcode sign.

Export to PPT

Close

Figure 2:

Chest X-ray showing massive right-sided pneumothorax with mediastinal shift to the left.

Export to PPT

The present day trend is to diagnose pleural pathologies such as pneumothorax, pleural effusion, lung consolidation, and collapse with bedside ultrasound with almost 100% accuracy. The bedside ultrasonography has been documented to be highly sensitive (87%) and specific (99%) for diagnosing pneumothorax in emergencies and intensive care units.^[1] However, many a times, it becomes difficult in early post-operative cardiothoracic surgical patients to perform lung ultrasound due to sternotomy/thoracotomy, chest drains, soft-tissue edema, high skin turgor, lung congestion and/or infection, and large surgical dressings. Moreover, also it further becomes inadequate in neonates and infants post-cardiac surgery due to above factors and ultrasound probe not fitting too well to the tiny chest wall. However, in this neonate, it was post-operative day 7 and main sternotomy wound was healing well and dressings were removed as skin had healed and healthy. We could successfully perform ultrasound and diagnose massive right pneumothorax and ICD was inserted before tamponade and hemodynamic collapse occurred. Whereas lung ultrasound has a sensitivity and specificity of 99% and 98%, respectively, for diagnosing neonatal pneumothorax,^[2,3] but the same has not been documented in the literature for post-cardiac surgical neonates and infants.