Continuous Caudal Epidural Analgesia for Congenital Lobar Emphysema: A Report Of Three Cases

Abstract

Various modalities of analgesia have been described for thoracotomy in congenital lobar emphysema. Caudal epidural analgesia with the catheter placed at thoracic level, provides preemptive, safe and effective analgesia to these patients while decreasing the anesthetic requirements. Since respiration is not depressed, there is little need for pressure ventilation. The analgesia can be extended in the postoperative period. Our case report illustrates this. Case Report The clinical and biochemical details of the patients are provided in Table 1. The induction of anesthesia differed in the three patients and is described separately below. Procedures common to all three patients were as follows: premedication was with atropine 0.1 mg and preoxygenation. A 20-gauge epidural catheter (Portex®; Hyde, UK) was passed through an 18-gauge hypodermic needle from the caudal epidural space up to T4-5 segments as measured on the outside. The distal end was tunnelled to the right flank. Bupivacaine 0.25% was injected at 0.15 mL/kg/segment for six segments (total of 2.2 mg/kg). Atracurium 0.5 mg/kg was administered only after thoracotomy for positive pressure ventilation with open chest. The infants were extubated at the end of surgery. In all three patients postoperative analgesia of more than 50% improvement of CRIES score (1) over 30 min was achieved with eight hourly injections of 0.2 mL/kg/segment (five segments) of bupivacaine 0.125%. The epidural catheters were removed on the fourth postoperative day. There were no complications in any of these cases.Table 1: Patient Presentation and Preoperative Arterial Blood Gas Analysis Values of the Three Patients with a Diagnosis of Congenital Lobar EmphysemaCase 1 Anesthesia was induced with halothane in oxygen. After lignocaine 4% (5 mg/kg) spray, the trachea was intubated with a 3.5-mm tube. Spontaneous ventilation with oxygen and halothane was continued. A caudal epidural catheter was passed. A right thoracotomy was performed to resect the affected lobe. Case 2 The caudal area was anesthetized with EMLA® (Astra, West Borough, MA) 1 h before surgery. Oxygen and halothane by mask were then administered in the left lateral position and the epidural catheter passed. The patient was placed supine. After lignocaine 4% spray, a 3.5-mm tube was passed into the right main bronchus, as confirmed by absence of breath sounds in the left hemithorax. Intraoperatively, to identify the affected lobe and to expand the collapsed left lower lobe, the endobronchial tube was withdrawn into the trachea. The affected lobe was excised. Case 3 Anesthesia was induced with propofol 2 mg/kg, and the trachea was intubated with a 4-mm tube after lignocaine spray. Spontaneous ventilation was maintained with oxygen and halothane. A caudal epidural catheter was passed. Because the whole left lung was affected, a pneumonectomy was performed. Discussion Congenital lobar emphysema causes respiratory distress, recurrent respiratory infections, and cyanosis in severe cases (2–4). The chest radiograph is diagnostic with hyperlucency of the emphysematous lobe with basal atelectasis of the lower lobe. The contralateral lung may be normal or atelectatic. A differential diagnosis includes pneumatocele, pulmonary cystic disease, and tension pneumothorax where the bronchovascular markings are not seen (2). There may be associated cardiovascular malformations. Surgical excision of the affected lobe is the treatment in infants under 2 months and in older infants with severe respiratory symptoms (4). Balanced anesthesia with opioids and inhaled anesthetics may necessitate positive pressure ventilation for respiratory depression. Spontaneous ventilation is preferred prior to thoracotomy and delivery of the affected lobe. Epidural blockade with a stable cardiovascular profile in children may provide excellent analgesia without depressing respiration (5). This technique also facilitates early extubation and faster recovery. In our three cases we used the technique of caudal thoracic epidural catheterization (6,7) to reach T4-5 for segmental analgesia with 0.15 mL/kg/segment (8) of local anesthetic. The advantages of this technique before thoracotomy are the provision of preemptive analgesia and reduction of anesthetic requirements and pressure ventilation during the critical phase until the thorax is open. The possible pitfalls are that there may be a difficulty in passing the catheter over the lumbosacral and thoracolumbar convexities of the spine or there may be an obstruction by a nerve root (6). Slow injection of a small volume (0.5–1 mL) of saline through the advancing catheter helps in overcoming these problems (9,10). The soiling of the catheter entry site is another problem that is solved by tunnelling (10). Kinking or doubling back of catheters in the epidural space (11) can prevent the catheter from reaching the midthoracic segments. A limitation of our technique was that a radiogram to confirm the position of the catheter tip was not performed. There was no kinking, as injection of the local anesthetic was free. The total dose of bupivacaine, 2.2 mg/kg, was within the limits of local anesthetic dose to avoid toxicity (5,6,8). The application of EMLA® enabled us to pass the catheter in Case 2 with the patient minimally anesthetized. Laryngoscopy and intubation, with the potential to cause apnea and laryngospasm, were avoided, with one anaesthetist maintaining the unintubated airway while another placed the catheter. The other two cases, managed by a single anaesthetist, were intubated before passage of the catheter for safety. The techniques for lung isolation in infants (12) are endobronchial intubation and bronchial blockade or with a Fogarty catheter or a univent tube. Bronchial blockade has the advantage that a lung can be segregated at will. With the end hole blocker of a univent tube suctioning, oxygenation and selective continuous positive airway pressure to the operative lung are possible. However, the smallest univent tube having a 3.5-mm inside diameter has an outer diameter of 7.5–8 mm and therefore is useful only in older children (13). Endobronchial intubation of the normal side leads to temporary collapse of the affected lobe with elimination of ventilation to the nonperfused lung segment on the diseased side. Karnak et al. (3) found loss of perfusion in the affected lobe in seven cases with ventilation intact on a pulmonary perfusion scan in eight patients. This acts as dead space ventilation. In our second case, the tracheal tube was placed endobronchially until the chest was opened and was pulled back to the trachea only when the diseased lobe was required to be identified. A large study should be completed before the lung segregation approach can be recommended in cases of lobar emphysema. There is conclusive basic scientific evidence by way of reduced central nervous system excitation, but ambiguous clinical confirmation, for the concept that preemptive analgesia before the initiation of nociceptive stimulus of surgery prevents or reduces subsequent pain (14–16). However, to provide lasting benefits, analgesia should be continued preemptively during the postoperative period. We attempted this in our three cases. In conclusion, thoracotomy for congenital lobar emphysema requires safe anesthesia and adequate analgesia, both intraoperatively and postoperatively. Our case reports demonstrate an approach using epidural anesthesia that we found to be safe and effective.