Review Article Anaesthetic implications of paediatric thoracoscopy Nandini Dave, Sarita Fernandes Department of Anaesthesiology, BYL Nair Hospital & TN Medical College, Mumbai - 400008, India Address for correspondence: Dr. Nandini Dave, C - 303, Presidential Towers, LBS Marg, Ghatkopar (W), Mumbai - 400086, Maharashtra, India. E-mail: [email protected] Abstract dia, atrial fibrillation, supraventricular extrasystoles etc.), mediastinal shift, hypertension or hypotension Anaesthetic care during thoracic surgical and hypercapnia. Pulmonary complications include procedures in children combines components of hypoxemia, hypercarbia, impaired hypoxic pulmonary the knowledge bases of paediatric anaesthesia with those of thoracic anaesthesia. This article vasoconstriction, re-expansion pulmonary oedema, highlights the principles of anaesthesia during atelectasis and pneumonia. There is always the possi- thoracoscopic surgery in children including bility of some major vessel injury and torrential bleed. preoperative evaluation, anaesthetic induction It is difficult to assess the blood loss during thoracos- techniques, maintenance anaesthesia and options copy. for postoperative analgesia. In addition, given the need to provide optimal surgical visualization during the procedure, one lung ventilation may be PRE-OPERATIVE EVALUATION required. Techniques to provide one lung ventilation in the paediatric patient and the principles of Patients presenting for thoracoscopic surgery should anaesthesia care during one lung ventilation are undergo a similar preoperative evaluation to those discussed. presenting for open thoracotomy with special empha- Key words: Thoracoscopy, anaesthesia, paeditaric sis on the degree of pulmonary and cardiac dysfunc- tion. It is customary to obtain a complete history, phys- INTRODUCTION ical examination and the following laboratory tests: haemoglobin, haematocrit, liver function tests, serum Thoracoscopy in children initially was proposed as a electrolytes and an X-ray Chest. Additional preopera- method of obtaining pulmonary biopsy specimens in tive evaluations such as pulmonary function test (PFT) immunocompromised patients. With further refine- and ECG are not routinely indicated but rather obtained ments in the technique and development of better in- based on the patients medical history and associated strumentation, the scope has widened tremendously underlying illness. Preoperative CT scan of the chest is with more complicated procedures like PDA ligation, useful in children with an anterior mediastinal mass. thymectomy, Heller’s myotomy, congenital diaphrag- Compression of greater than 50% of the cross section- matic hernia repair etc. being performed with the help al area of the trachea on CT imaging can be used to of thoracoscopy. identify the high risk population in whom general an- aesthesia with loss of spontaneous ventilation can lead Anaesthesia for paediatric thoracoscopy[1,2] is very chal- to total airway obstruction. Options include preoper- lenging as the paediatric anaesthesiologist has to be ative radiation or chemotherapy to shrink the mass or well versed in the various techniques of providing one induction of general anaesthesia while maintaining lung anaesthesia and manage the intra and postopera- spontaneous ventilation with cardiopulmonary bypass tive complications. Utmost vigilance is needed as one as a backup measure. Simple bedside spirometry—FVC, encounters arrhythmias (such as ventricular tachycar- FEV1 and the ratio FVC/FEV1 may be performed in old- Journal of Minimal Access Surgery | March 2005 | Volume 1 | Issue 1 8 Dave N, et al: Anaesthetic implications of paediatric thoracoscopy er children to assess the degree of obstructive lung Inhalational Sevoflurane or Halothane or intravenous disease and ensure that the minimum criteria for wedge Thiopentone or Propofol induction is followed by a or lung resection are satisfied. neuromuscular blocking drug to facilitate endotrache- al intubation. PRE-OPERATIVE PREPARATION Intraoperative analgesic used is generally Fentanyl 1-2 Chest physiotherapy, good nutrition, bronchodilator/ microgram/kg or Pentazocine 0.6 mg/kg, antibiotic therapy, steroid supplementation etc. helps in optimizing the patients condition prior to surgery. Anaesthesia is maintained either by using inhalational agents or infusions of Propofol. Patient is maintained As there is always a possibility of conversion to open on controlled ventilation using short acting muscle thoracotomy, blood should be kept in reserve. relaxants. Standard perioperative monitoring includes The goals of anaesthesia include: minimizing airway 1. ECG reactivity, optimizing gas exchange, maintaining sta- 2. Pulse oximetry ble cardiovascular function, preventing ventilatory 3. End tidal CO2 measurement depression and providing adequate pain relief in the 4. Noninvasive BP monitoring postoperative period. 5. Continuous temperature monitoring. The bladder is catheterised and urine output monitored Anaesthesia technique for thoracoscopy when surgery is prolonged or significant blood loss A variety of anaesthesia techniques can be used for expected. thoracoscopy. Older children (> 8 years of age or weight > 30-35 kg) can be managed using most of the Premedication and anaesthesia management techniques used in adults. Special techniques for iso- In otherwise healthy patients without airway compro- lation of the operative lung are suitable for smaller mise intranasal Midazolam 0.3 mg/kg in children with- children. out intravenous access or rectal or oral Midazolam 0.5- 0.75 mg/kg administered 15 to 20 minutes prior to 1. Local anaesthesia- may be possible in older adoles- anaesthesia induction provides anxiolysis, easy sepa- cents. This technique is usually reserved for brief ration from parents and acceptance of face mask. procedures without involved intrathoracic surgical manipulation for ill patients with unacceptable risk Blood loss during a diagnostic thoracoscopy is usually of perioperative morbidity following general anaes- minimal. It is however advisable to have preferably two thesia. Following IV sedation, the lateral chest wall venous accesses prior to the start of the procedure as and parietal pleura are infiltrated with local anaes- the surgery is performed in the lateral decubitus posi- thetic to provide anaesthesia for trocar placement. tion. Table 1: Tube selection for single lung ventilation in children[3] If central venous pressure monitoring is necessary, in- Age ETT (ID) BB (Fr) Univent DLT (Fr) ternal or external jugular monitoring on the side of 0.5-1 3.5-4 2 thoracoscopy is recommended. In patients with severe 1-2 4-4.5 3 cardiac instability and where major haemodynamic fluc- 2-4 4.5-5 5 4-6 5-5.5 5 tuations are expected, invasive arterial blood pressure 6-8 5.5-6 5 3.5 monitoring is used. Atropine is administered as a vago- 8-10 6 cuffed 5-7 3.5 26 lytic and antisialogogue. Antiemetics and H2 antago- 10-12 6.5 cuffed 7 4.5 26-28 12-14 6.5-7 cuffed 7 4.5 32 nists are administered in patients at risk for aspira- 14-16 7 cuffed 7-9 6 35 tion. 16-18 7-8 cuffed 9 7 35 9 Journal of Minimal Access Surgery | March 2005 | Volume 1 | Issue 1 Dave N, et al: Anaesthetic implications of paediatric thoracoscopy 2. Regional techniques include thoracic epidural an- 1. Selective mainstem intubation is a simple and aesthesia, thoracic paravertebral blocade, multiple quickly achieved means of one lung ventilation in intercostal blocks or intrapleural analgesia.The stel- patients whose small size precludes placement of a late ganglion block also temporarily eliminates the DLT or Univent tube. The tracheal tube should be cough reflex which can be elicited during manipu- one half smaller than usual, based on patient’s age lation of the pulmonary hilum. as the diameter of the mainstem bronchus is small- Regional anaesthesia techniques and local anaes- er than that of the trachea. Bronchoscopic guidance thesia with sedation offers the advantage of main- or fluoroscopy can aid correct placement. As an taining spontaneous ventilation and interferes less uncuffed tracheal tube might not be totally occlu- with surgical exposure. However patients with sig- sive to avoid soilage and inadvertent ventilation of nificant pulmonary disease are sometimes unable the operative side, a cuffed tracheal tube is recom- to compensate for the temporary loss of pulmo- mended in patients > 2 years of age (Figure 1). nary surface area due to partial collapse of the lung on the side of the thoracoscopy. 2. Double lumen tube Local and regional techniques are possible only in When patient size permits, a DLT is preferable as it the older age group. In majority of cases thoracos- has advantages over other techniques. copy is always performed under general anaesthe- 1. Rapidly and easily separating the lungs sia with lung isolation techniques whenever feasi- 2. Allowing for suctioning of both lungs ble. 3. Providing rapid switch to two lung ventilation as 3. General anaesthesia and one lung ventilation: With necessary based on patients status. general anaesthesia and positive pressure ventila- 4. Improving oxygenation by applying CPAP to the tion, intrathoracic visualization and surgical access operative lung and PEEP to the non-operative lung. can be impaired by lung movement. To overcome this problem, thoracoscopy is performed using tech- In children left sided DLTs are used almost exclusively niques to isolate the lung and provide one lung because they are easier to place and eliminate con- ventilation. This