Anaesthetic Management of a Case of Congenital Lobar Emphysema
ANAESTHETIC MANAGEMENT OF A CASE OF CONGENITAL LOBAR EMPHYSEMA
1. Dr. V.Jayaraman, Professor, Department of Anaesthesiology, Saveetha Medical College, Chennai, Tamilnadu, India.
2. Dr.VR.Kalarani, 3rd year MD(Anaesthesia) PG, Department of Anaesthesiology, Saveetha Medical College, Chennai, Tamilnadu, India.
3. Dr.P.Manikandan, Senior Resident (NICU), Department of Pediatrics, Saveetha Medical College, Chennai, Tamilnadu, India.
ABSTRACT:
Congenital lobar emphysema (CLE) or congenital lobar over inflation is a rare pulmonary anomaly that causes respiratory distress in neonates. CLE presents significant challenges in diagnosis and management. We reported a case of two-month old infant with respiratory distress and pneumonia related to CLE affecting the left upper lobe. Lobectomy was performed under general anaesthesia with spontaneous and controlled lung Ventilation. The case was challenging, as it involved careful and planned anaesthetic management of lung separation as well as prevention of hyperventilation of the un-involved lung.
KEYWORDS: Congenital Lobar Emphysema, Pneumonia, Respiratory Distress, Lobectomy, Neonatal Intensive care Unit.
INTRODUCTION
Congenital lobar emphysema (CLE) is a rare congenital malformation of the lung characterized by normal architecture with lobar over aeration and subsequent respiratory distress secondary to partial obstruction of the bronchus via the ball valve effect. It is also known as congenital lobar over inflation or infantile lobar emphysema.1,2 The incidence is reported to be between 1 in 70,000 and 1 in 90,000 live births with male predominance.3 It presents as life threatening respiratory distress especially within the first 6 months of life due to compression atelectasis, hypoxia, mediastinal shift and associated hypotension.4,5 Aetiology is unknown up to 50% cases, but several intrinsic and extrinsic causes have been described. Chest radiograph shows mediastinal shift and hyperinflation that is often confused with pneumonia and pneumothorax.6 Positive pressure ventilation or assist ventilation can worsen hyperinflation and hemodynamic collapse can result. We discuss the anaesthetic management of a 2 months old infant scheduled for left lobectomy with emphasis on prompt diagnosis and use of positive pressure ventilation in management of a case of CLE.
CASE REPORT
A 60 days old boy baby born in an outside hospital at 36weeks(late preterm) by normal delivery with meconium stained liquor, developed respiratory distress, admitted and treated in NICU and discharged on 10th day of life. However, mother noticed that he started developing respiratory distress with suprasternal and intercostal recession, poor feeding since 25th day of life. Baby was admitted in a tertiary care hospital, Air entry on the left side of the chest was found to be decreased, heart sounds heard better on the right side. Pulse oximeter showed saturation of 85% while using oxygenhood. X ray chest showed hyper inflation of left upper lobe with pneumonitis and collapsed lower lobe. CT chest confirmed the above findings and diagnosis of CLE with pneumonia was made. Child was treated with IV antibiotics for pneumonia. In view of persisting respiratory distress even after treating for pneumonia child was admitted in our hospital for further treatment and surgical management.
On arrival, the child was found awake, underweight (wt- 3.9kg) and in respiratory distress. There were marked intercostal and subcostal retractions. Air entry was decreased in the left hemi thorax with expiratory wheeze noticed on left upper lobe. Saturation was 85% on room air and 92% under oxygen hood. There was no cyanosis. Routine haematological studies and biochemical investigations were normal. X-Ray showed hyperlucency of left upper zone with rightward mediastinal shift, and segmental collapse of left lower zone (Fig-1). After admission, respiratory distress progressed to impending respiratory failure. Child was intubated with 4 size endotracheal tube and fixed at 11 cm and connected to mechanical ventilator with the optimal pressure settings. Child had cardiac arrest but was effectively revived. Echo was done to rule out any associated cardiac anomaly and it was normal.
The child was scheduled for emergency left lobectomy, blood was ordered and no sedative premedication was prescribed. In the OT, basic monitoring like ECG, NIBP, saturation and temperature monitoring were connected and 2 peripheral lines secured. Standard precautions to avoid hypothermia were taken and premedication with iv atropine 0.1mg and fentanyl 4 mcg were given. Induction was done with 100% O2 and sevoflurane. Gentle assisted ventilation was done with hand using a Jackson Rees circuit, neonate placed in the right lateral position and anaesthesia maintained with sevoflurane 2% in 100% O2. Intraoperative analgesia was provided with intravenous fentanyl 4 mcg in divided doses. A left upper lobectomy was performed through the 4th intercostal space. The saturation rose up to 100% after the lobectomy. Hemodynamics throughout the two hour surgical procedure (Fig-3) was stable. After lobectomy, the left lower lobe was expanded using gentle manual recruitment maneuver. Blood and fluid loss monitored and replaced with 40 ml of warmed Ringer's Lactate and 60 ml of fresh packed cells. At the end of the surgery, an intercostal nerve block was given by the surgeon under direct vision using 4 ml of 0.25% Bupivacaine. The baby was shifted to the Neonatal intensive care unit with ICD and endotracheal tube insitu. Post operative analgesia was provided by rectal paracetamol. Child was ventilated in the postoperative period using pressure controlled ventilation for 36 hours and carefully extubated. Intercostal drain removed on 5th postoperative day. Postoperative x ray revealed expanded left lung and normal position of mediastinum (Fig-2). Child made a rapid uneventful recovery and was discharged on the 7th post operative day.
Fig-1: Pre op Chest X-rayFig-2: Post op Chest X-ray
Figure-1: Preoperative chest radiograph showing hyperlucency on the left upper zone, rightward mediastinal shift and segmental collapse of left lower zone
Figure-2: Postoperative chest radiograph AP view showing expanded left lung and normal position of mediastinum.
Figure-3: Resection of left upper lobe and Specimen of the resected emphysematous left upper lobe
DISCUSSION
Congenital lobar emphysema (CLE) is a developmental anomaly of the lower respiratory tract that is characterized by hyperinflation of one or more of the pulmonary lobes.7,8 Other terms for CLE include congenital lobar overinflation and infantile lobar emphysema.1,2,9 Progressive lobar hyperinflation is likely the final common pathway that results from a variety of disruptions in bronchopulmonary development. These result from abnormal interactions between embryonic endodermal and mesodermal components of the lung. Disturbances may leads to change in the number of airways or alveoli or alveolar size.10 However, a definitive causative agent cannot be identified in 50 percent of cases.11
The most frequently identified cause of congenital lobar emphysema (CLE) is obstruction of the developing airway, which occurs in 25 percent of cases.7 Airway obstruction can be intrinsic or extrinsic, the former being more common. This leads to the creation of a "ball-valve" mechanism in which a greater volume of air enters the affected lobe during inspiration than that leaves during expiration, producing air trapping.
CLE can be hypo alveolar or polyalveolar, based on number of alveoli within each acinus.12 Usually one lobe is affected, but bilateral involvement is seen in 20%.13,14 Congenital heart disease is associated in 12-14% of these patients.4 Clinical signs of CLE include tachycardia, tachypnea, and chest retractions which progress to respiratory distress and respiratory failure. Asymmetric expansion of the hemithorax, rhonchi, displacement of apical impulse, hyper resonant percussion on affected side, and diminished breath sounds and heart sounds may be noted. Lobar hyperinflation, atelectasis of contra lateral lung, mediastinal shift, and flattening of ipsilateral diaphragm are typically seen on CXR. Thus, the disease is often confused with pneumonia and pneumothorax, 15 even resulting in wrongful placement of a chest drain. CT and MRI help in diagnosis of CLE, but the single photon emission tomography ventilation-perfusion lung scan is confirmatory.14 This scan may reveal hypo perfusion of affected lobe due to compression of vasculature and hyper perfusion of normal lobes by shunted blood. While conservative management for CLE has been described, lobectomy is the mainstay of treatment. The management of a child with CLE with pneumonia or respiratory failure is controversial. Clearing the infection prior to surgery can improve pulmonary mechanics but unrelieved compression atelectasis is detrimental.
The physiological considerations for anaesthetizing these patients include ventilation and perfusion impairment of the lung in an infant undergoing thoracic surgery in the lateral decubitus position. Unlike adults, infants with unilateral lung disease does not improve oxygenation when the healthy lung is dependent and the diseased lung is nondependent.16 In infants, oxygenation is optimized when the healthy lung is nondependent.17 This difference is due to the more compliant chest wall of the infant, which cannot completely support the dependent lung. The FRC is consequently closer to the residual volume and the airway closure becomes more likely in the dependent lung.18 The advantage of the abdominal hydrostatic pressure gradient to the dependent diaphragm is lesser in infants. Due to their small size; the favourable increase in perfusion to the dependent lung is also less. An infant's ability to tolerate one lung ventilation (OLV) is affected by these considerations and the position for thoracic surgery is unfavourable for them when compared to adults. Inhalation induction is preferred because spontaneous ventilation should be maintained until either the chest is opened or OLV of the contra lateral lung is achieved.5
Positive pressure ventilation is due to a ball valve effect, which leads to over distension of the emphysematous lobe, worsening of mediastinal shift, reduction in cardiac output and hemodynamic collapse. However gentle assisted manual ventilation may be needed if there is hypoventilation during induction due to poor respiratory reserve. Nitrous oxide should be avoided.
The optimum ventilatory technique has been discussed by many authors. Tempe suggests that IPPV is best avoided as the critical airway pressure is not known.16 Gentle manual ventilation keeping the airway pressure at 20-25 cm of H2O before thoracotomy has been described.5 PRVC mode is an attractive option for mechanical ventilation if available. High frequency ventilation has been used successfully in the patients with CLE, as low airway pressures are especially suitable.19 The risk of over distension leading to a catastrophic hemodynamic crisis should never be underestimated and the surgeon should be ready for immediate thoracotomy during induction. OLV is not generally indicated for open thoracotomies in neonates and infants because the surgeon is usually able to manually retract the lung. In neonates and infants, the only options for lung isolation are either mainstem intubation or placement of bronchial blockers. Use of double lumen Marraro tubes has been reported as well.20
Maintenance of anaesthesia is usually done with inhalational agents. Opiates like morphine are avoided due to the risk of postoperative respiratory depression. Epidural analgesia with a caudal catheter inserted up to the thoracic level and using local anesthetics has been described.21 Intravenous ketamine in boluses of 1.5 mg/kg has been recommended for intraoperative analgesia.5, 20 In most of the cases the trachea can be extubated at the end of the surgery. It was decided to electively ventilate our patient in view of poor preoperative respiratory condition.
CONCLUSION
An infant presenting in emergency with progressively increasing respiratory distress should be viewed with a suspicion for CLE. Induction of anesthesia in a patient with congenital lobar emphysema can be challenging for the anesthesiologist because of the risk of overinflating the lung with either infant induced airway Valsalva effects or positive airway pressure administered by the anesthesiologist. Anesthetic induction with inhalational agents is desirable; however, if IPPV is necessary, gentle ventilation or pressure controlled ventilation with a pressure limit of 20 cm of H2O should be carried out until thoracotomy. A standby surgical team should be available during induction of anesthesia and nitrous oxide should be avoided till lobectomy is perfomed. The successful outcome emphasizes the importance of use of low pressure manual ventilation in management of such cases. The case highlights importance of team approach in the difficult cases like this which yields a rewarding outcome.
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