Anaesthetic management of a child with pulmonary agenesis for laparoscopic inguinal hernia repair.

Sir,

Pulmonary agenesis is a rare congenital malformation in which there is total absence of the bronchial tree, alveolar parenchyma, pulmonary and bronchial vasculature.[1]

A 20-month-old 10-kg male child, known case of left pulmonary agenesis, was scheduled for right inguinal hernia repair. He had undergone open right inguinal hernia repair last month. Due to recurrence, the surgeons now opted for laparoscopic repair as they wanted to approach through fresh surgical planes. On pre-anaesthetic evaluation, the child was active with room air oxygen saturation of 100%. Blood investigations were within normal limits. Recent chest X-ray was suggestive of (s/o) absent left lung with hyperinflated right lung with no mediastinal shift [Figure 1]. On contrast-enhanced computed tomography (CECT) chest, left lung, left main bronchus, left main pulmonary artery and left pulmonary vein were absent. CECT abdomen was s/o absent left kidney and DMSA scan revealed normal functioning right kidney. CECT neck revealed segmentation anomalies in cervical and proximal dorsal spine. On two-dimensional echocardiography, a small patent ductus arteriosus was detected with left-to-right shunt.

Figure 1

Chest X-ray of child with left pulmonary agenesis

Parental consent and 6-hour fasting was ensured. He had an intravenous (iv) cannula in situ. Midazolam 0.5 mg iv was given and the child was wheeled in to the operating room with oxygen and pulse oximetry monitoring. Three-lead electrocardiography and noninvasive blood pressure monitors were attached. Intravenous induction of anaesthesia was done with fentanyl 20 μg, propofol 20 mg and atracurium 5 mg. Laryngoscopy was done using C-MAC video laryngoscope and trachea was intubated with size 4.0 cuffed endotracheal tube.

Pressure control mechanical ventilation was initiated with the following settings: inspiratory pressure 14 cmH2O, respiratory rate 24/min, positive end-expiratory pressure (PEEP) 5 cmH2O and 0.5 FiO2, delivering a tidal volume of 50 mL and end-tidal carbon-dioxide (EtCO2) 42 mmHg. Carbon dioxide was gradually insufflated to attain a pneumoperitoneum, and intra-abdominal pressure (IAP) was not allowed to exceed 10 mmHg. The delivered tidal volume decreased after creating pneumoperitoneum and EtCO2 increased to 62 mmHg. Inspiratory pressure was then increased to 17 cmH2O and respiratory rate to 28/min. Anaesthesia was maintained with isoflurane in air/oxygen (50/50), maintaining a MAC (Minimum Alveolar Concentration) of 1.1. Boluses of fentanyl 10 μg and atracurium 2 mg were given along with paracetamol 100 mg iv. The child's blood pressure and heart rate were maintained throughout the procedure and no episode of desaturation was recorded. Neuromuscular blockade was reversed, and the child was extubated and shifted to the recovery area with oxygen by face mask and monitoring of vitals. He was allowed orally after 4 hours and discharged home on the second postoperative day.

In patients with pulmonary agenesis, positive pressure ventilation poses a higher risk of barotrauma, pneumothorax, pneumomediastinum and interstitial emphysema to the single lung tissue.[2] Laparoscopic surgery can further increase the risk, as the respiratory changes due to pneumoperitoneum are subjected to single delicate lung tissue. The co-malformations associated with pulmonary agenesis can further result in anaesthetic challenges.[2]

We used C-MAC video laryngoscope for intubation, to avoid neck extension as the child had segmentation anomalies of cervical spine. Since the child had no respiratory compromise, we planned to proceed with laparoscopic surgery. Slow and gradual carbon dioxide insufflation was ensured to avoid vagal response to pneumoperitoneum which is predominant in children.[3] IAP was not allowed to exceed 10 mmHg to avoid excessive cardiorespiratory changes. Various authors recommend restriction of IAP to 6 mmHg in infants and 12 mmHg in older children as these pressures have minimal effects on cardiac index.[34] Amin et al. recommended the use of lung protective ventilation and proposed the requirement of higher peak pressures to overcome airway resistance and prevent shunting and hypoxemia in such patients.[2] We used similar ventilation strategy. Pennant proposed that children have a low functional residual capacity (FRC) which quickly falls below the closing capacity due to the pneumoperitoneum in laparoscopic surgery, producing small airway closure, atelectasis, intrapulmonary shunting and hypoxaemia.[4] Hence, the use of PEEP was recommended and thus applied.

In conclusion, laparoscopic surgery in a patient with pulmonary agenesis poses a great challenge for the anaesthesiologist, as the strain of respiratory changes associated with pneumoperitoneum is subjected to single lung tissue.

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Conflicts of interest

There are no conflicts of interest.