General and Thoracoabdominal Surgery




General Principles




  • 1.

    Many of the children requiring thoracoabdominal procedures are neonates and preterm infants and therefore demand special considerations.


  • 2.

    In most cases, the pathophysiology of the surgical disease dictates the optimal anesthesia management. The anesthesiologist should understand the effects of the lesion on normal physiology.


  • 3.

    Surgery is very rarely required immediately; usually some time is available for preoperative evaluation and resuscitation as necessary. The optimum time for surgery must be decided by consultation among anesthesiologist, neonatologist, and surgeon.


  • 4.

    For emergency abdominal surgery, the problem of the full stomach must be considered. (Even if the child has not eaten for some time, secretions accumulate in the stomach, and emptying may be delayed by obstruction or ileus.) Children with gastroesophageal reflux are at increased risk.



    • a.

      Remember the effects of drugs on the barrier pressure (i.e., lower esophageal pressure [LES] minus intragastric pressure). Barrier pressure is reduced by atropine, diazepam, inhalational anesthetics, and cricoid pressure. It is increased by metoclopramide, pancuronium, and vecuronium, and it is little changed by succinylcholine.


    • b.

      Drugs can be used to reduce the volume and acidity of gastric contents: cimetidine (oral or rectal), ranitidine, metoclopramide, and sodium citrate.



    Possible plans of action:



    • i.

      Pass a gastric tube and aspirate the stomach where appropriate. In suitable children, pretreat with medications to reduce volume and acidity of the gastric contents.


    • ii.

      Neonates and small infants at high risk: aspirate stomach contents through a vented gastric tube in the supine, right, and left decubitus position (in neonates and infants this may remove up to 95% of fluid gastric contents), preoxygenate, and perform a RSI or awake sedated intubation.


    • iii.

      Older children: aspirate stomach contents (if appropriate) and perform a RSI with cricoid pressure. Cricoid pressure must be commenced as soon as any drugs are given that may reduce LES. There is still no relaxant drug that can replace succinylcholine for speed of onset, offset, and intensity of neuromuscular block.


    • iv.

      Make sure that the child is deeply anesthetized and relaxed before tracheal intubation. Struggling during attempts at intubation in an incompletely anesthetized and relaxed child is a common precursor to vomiting and aspiration.



    Remember: During RSI, succinylcholine does not increase intragastric pressure in children younger than 10 years of age, and pretreatment with a low-dose nondepolarizing relaxant is not indicated (see Chapter 3, page 70 ).


  • 5.

    During thoraco-abdominal surgery, blood loss may be considerable; be prepared to handle a major blood transfusion (see Chapter 4, page 135 ).


  • 6.

    For major abdominal surgery, always establish intravenous access in the upper limbs or neck. The inferior vena cava (IVC) may rarely have to be clamped or may be otherwise compressed during the operation; this renders transfusion via the lower limb veins ineffective.


  • 7.

    N 2 O diffuses into the lumen of gas-containing bowel, causing further distention and difficulties for the surgeon. Do not use N 2 O when conditions predispose to this condition (e.g., intestinal obstruction).


  • 8.

    The airways are small and, during lung surgery, bronchial secretions (often sanguinous) may accumulate and interfere with ventilation. Perform tracheobronchial toilet as indicated.


  • 9.

    During thoracotomy, <SPAN role=presentation tabIndex=0 id=MathJax-Element-1-Frame class=MathJax style="POSITION: relative" data-mathml='V./Q.’>V./Q.V./Q.
    V . / Q .
    ratios in the lungs are disturbed; therefore increase the inspired O 2 concentration to maintain an acceptable SaO 2 .


  • 10.

    In infants and small children, retracting the lungs may obstruct major airways, impairing ventilation, or it may compress the heart and great veins, leading to a precipitous decrease in cardiac output and hence in blood pressure. Constant monitoring of breath sounds via stethoscope, shape of the capnogram, and observation of SaO 2 is essential. In the event of decreasing saturation, bradycardia, hypotension, or impaired ventilation:



    • a.

      Ask the surgeon to remove all retractors immediately.


    • b.

      Ventilate the lungs with 100% O 2 .


    • c.

      Use large manually delivered tidal volumes with relatively high peak inflation pressures to reexpand areas of atelectasis.



  • 11.

    Even children who require minor surgery (e.g., herniotomy) may be preterm and/or have other conditions (e.g., anemia) that can complicate anesthesia and require special precautions (see Chapter 6 ).


  • 12.

    Many general surgery procedures can now be performed with the use of video-assisted endoscopic techniques. It is anticipated that additional advances in these techniques will further extend the scope of minimally invasive pediatric surgery.



SPECIAL CONSIDERATIONS FOR MINIMALLY INVASIVE/ENDOSCOPIC SURGERY IN INFANTS AND CHILDREN


Advances in optical systems, video equipment, and surgical instrumentation over the past decade have allowed the extensive development of endoscopic surgery techniques for infants and children. The advantages are smaller scars, less postoperative pain, and earlier discharge, plus presumably less psychologic upset. In the future, robotic surgery via endoscopic access may become the optimal treatment for many surgical conditions.


Special Considerations




  • I.

    All procedures planned as endoscopic may require urgent open operation should unexpected complications arise; always be prepared for emergency laparotomy or thoracotomy.


  • II.

    Bleeding may occur and may be difficult to rapidly control until an open operation is performed; ensure that reliable large-bore intravenous routes are established.


  • III.

    Access to the child may be limited by the equipment required for minimally invasive and especially for robotic surgery: ensure that you can adequately monitor the child and rapidly intervene should this be required.


  • 1.

    Laparoscopic procedures



    • A.

      Physiologic changes secondary to a CO 2 pneumoperitoneum.



      • i.

        The diaphragm is splinted with a consequent decrease in chest wall compliance. This effect is increased if the child is placed in the Trendelenburg position. Elevation of the diaphragm is followed by decreasing lung volumes, increasing the potential for airway closure to occur during tidal breathing and consequent hypoxemia.


      • ii.

        Increased intraabdominal pressure (IAP) leads to decreased venous return, decreased cardiac output, and increased total systemic resistance. The magnitude of these effects is related to the IAP and is increased if the child is placed in the reverse Trendelenburg position. These hemodynamic effects are magnified in the volume-depleted child.


      • iii.

        Carbon dioxide is readily absorbed into the circulation increasing the PaCO 2 and the requirement for increased ventilation. Positioning, pneumoperitoneum, and the requirement for increased ventilation may cause the PIP to markedly increase. Absorption of CO 2 may be greater in children than in adults owing to the physiologic properties of the peritoneum.


      • iv.

        The extent of the above changes depend upon the pressure within the abdomen. Pressures up to 5 mm Hg cause very little effect; up to 15 mm Hg is well-tolerated by healthy children in a neutral horizontal position. Positions other than horizontal or IAP greater than 15 mm Hg may cause serious cardiorespiratory derangements that require interventions.



    • B.

      Anesthesia management.



      • i.

        Careful preoperative assessment of cardio-respiratory status, state of hydration, and volume replacement is necessary. Respiratory or cardiac disease and/or volume depletion could cause adverse responses to induced pneumoperitoneum. Volume status should be optimized (i.e., in infants with pyloric stenosis) and any cardio respiratory limitations considered carefully preoperatively.


        Limiting the IAP and careful positioning may permit some children with cardio-respiratory disease to tolerate pneumoperitoneum but some may not be ideal candidates for this surgery (e.g., children with Fontan physiology).


      • ii.

        Controlled ventilation with increased positive inspiratory pressure is required. Oxygenation and EtCO 2 should be closely monitored, though the latter may be unreliable and give false low readings in infants. Increases in F i O 2 and minute ventilation (MV) are required. MV may need to be increased by 66% to maintain near homeostasis. Up to 5 cm PEEP may be required.


      • iii.

        Nitrous oxide should not be used:




        • When bowel distention is possible.



        • When air embolism might occur.



        • Intraabdominal cautery is used. (N 2 O supports combustion.)



      • iv.

        For upper abdominal surgery, a gastric tube should be passed to empty the stomach and improve exposure. For lower abdominal surgery, either have the child empty the bladder preoperatively or pass a urinary catheter. For pyloromyotomy, a small amount of air may be injected into the stomach via the gastric tube to check the integrity of the duodenal mucosa.


      • v.

        Monitor ventilation in both lungs throughout using a stethoscope. When the pneumoperitoneum is created in small infants, the cephalad movement of the diaphragm and lungs may cause the tip of the endotracheal tube to enter a bronchus. In addition, pneumothorax is a recognized complication and should be watched for. The addition of positive end-expiratory pressure may decrease the adverse effects of high IAP and also limit the potential effects of pneumothorax.


      • vi.

        Heart rate should be monitored during all intraabdominal manipulations; brisk vagal reflexes may be observed and require immediate cessation of surgical manipulations and treatment with IV atropine.


      • vii.

        Carbon dioxide embolism is very rare, but it has occurred during laparoscopy, causing cardiovascular collapse. Monitor carefully throughout the procedure and notify the surgeon immediately if there are any unexplained physiologic changes such as a sudden decrease in EtCO 2 or blood pressure, or a wind-mill murmur.




  • 2.

    Visually assisted thoracic surgery (VATS)



    • A.

      Physiologic considerations.



      • i.

        Infants have a high metabolic rate for oxygen and a high Va/FRC ratio. Any compromise in ventilation rapidly leads to hypoxemia.


      • ii.

        In infants in the lateral decubitus position for intrathoracic procedures, ventilation of the uppermost lung exceeds that of the dependent lung, but perfusion favors the dependent lung. There is increased <SPAN role=presentation tabIndex=0 id=MathJax-Element-2-Frame class=MathJax style="POSITION: relative" data-mathml='V./Q.’>V./Q.V./Q.
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        mismatch.


      • iii.

        In order to visualize the intrathoracic structures some degree of lung collapse must occur. This may be obtained by selective one-lung ventilation or as a result of gas insufflation into one hemithorax. In the latter case, some gas transfer can occur on the operated side but <SPAN role=presentation tabIndex=0 id=MathJax-Element-3-Frame class=MathJax style="POSITION: relative" data-mathml='V./Q.’>V./Q.V./Q.
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        mismatch is further increased.


      • iv.

        One-lung ventilation tends to direct perfusion away from the unventilated lung because of hypoxic pulmonary vasoconstriction (this is partly attenuated by inhalational anesthetics or other drugs) and mechanical effects within the collapsed lung thus normalizing <SPAN role=presentation tabIndex=0 id=MathJax-Element-4-Frame class=MathJax style="POSITION: relative" data-mathml='V./Q.’>V./Q.V./Q.
        V . / Q .
        relationships somewhat.


      • v.

        Absorption of insufflated CO 2 from the pleural cavity occurs and requires increased pulmonary ventilation for homeostasis to be achieved.


      • vi.

        In this situation PEEP is also quite helpful in preserving ventilation of the dependent lung.


        In summary, oxygenation and ventilation during VATS is unpredictable, requires careful monitoring, and a high F i O 2 will likely be necessary, especially in small infants. However VATS has been very successfully employed in a variety of neonatal and pediatric thoracic procedures.



    • B.

      Anesthesia management for VATS.



      • i.

        Careful preoperative evaluation of the cardiorespiratory system and the volume status is essential.


      • ii.

        A plan for one lung ventilation must be developed, some alternatives are (also see Congenital Lobar Emphysema):



        • a.

          Plain endotracheal tube ( no Murphy eye) guided into the contralateral main bronchus. This is the usual option for small infants. A tube one size smaller than predicted for normal use should be used. The tube can usually be inserted blindly into the (R) main bronchus. Right upper lobe atelectasis may occur in this situation. A fiberoptic bronchoscope or stylet is usually necessary to enter the (L) main bronchus. Using this technique, it is not possible to suction or inflate the operated side without withdrawing the tube.


        • b.

          A bronchial blocker may be placed on the operated side. A Fogarty catheter has been used in small infants, although there is no central channel for suction or to allow the lung to collapse completely, it has a high pressure cuff and it might cause damage to the bronchial mucosa. Low pressure cuffs are found on biliary catheters, which may also be used as a bronchial blocker. Bronchial blockers in small infants may be difficult to accurately position and may become displaced—possibly causing serious airway obstruction.


          In children over 2 years, the Arndt 5 Fr pediatric bronchial blocker may be used, which has a high volume low pressure cuff. With the guide wire removed, this channel may also be used to suction or deflate the operated lung.


          This blocker is inserted via a special adaptor into the endotracheal tube and guided into position using a FOB passed through the wire loop on the tip of the blocker. The use of the Arndt 5 Fr blocker passed through the trachea external to the endotracheal tube has also been described. The blocker is passed into the trachea before intubation and positioned either by fluoroscopy or with the aid of the FOB.


        • c.

          The Univent tube may be used in children of 6 years or over and has the advantage of a channel to suction the operated side bronchus. It should be positioned with the aid of a FOB. The Univent tube is available in 2 pediatric sizes that may be suitable for older children:




          • 3.5 mm Univent tube – external diameter 7.5 to 8 mm (= 5.5 mm ID plain tube)



          • 4.5 mm Univent tube – external diameter 8.5 to 9 mm (= 6.5 mm ID plain tube)



        • d.

          Double lumen endotracheal tubes (26 Fr) may be successfully inserted into children of 6 to 8 years of age. Correct positioning should always be confirmed with the FOB. A very small double lumen tube (designed by Marraro) for use in infants is only available as a special product from Smiths Industries (Portex) Inc.



      • iii.

        Anesthetic agents that interfere with normal hypoxic pulmonary vasoconstriction (e.g., halothane) should be avoided to ensure that pulmonary blood flow is optimally distributed away from the collapsed lung. Low concentrations of isoflurane or intravenous agents (e.g., propofol, fentanyl) are preferred.


      • iv.

        During one-lung ventilation (OLV) the child must be closely monitored to detect any displacement of the device used. If obstruction to ventilation should occur, the cuff of a blocker should be immediately deflated.


      • v.

        Following a period of OLV, the lung on the operated side should be carefully observed for reinflation. A postoperative chest x-ray should be obtained to exclude persistent atelectasis.





Suggested Reading


  • Rothenberg S.S.: Thoracoscopic pulmonary surgery. Semin Pediatr Surg 2007; 16: pp. 231-237.
  • Choudhry D.K.: Single-lung ventilation in pediatric anesthesia. Anesth Clinics N Am 2005; 23: pp. 693-708.
  • Marciniak B., Fayoux P., Hebrard A., et. al.: Fluoroscopic guidance of Arndt endobronchial blocker placement for single-lung ventilation in small children. Acta Anaesthesiol Scand 2008; 52: pp. 1003-1005.
  • Pawar D.K., Marraro G.A.: One lung ventilation in infants and children: experience with Marraro double lumen tube. Paediatr Anaesth 2005; 15: pp. 204-208.



  • Congenital Defects that May Necessitate Surgery During the Neonatal Period


    Congenital Lobar Emphysema


    Abnormal distention of a lobe (usually the upper or middle lobe) compresses the remaining normal lung tissue and displaces the mediastinum; respiratory distress and cyanosis result. When severe, this condition manifests as an extreme emergency during the early neonatal period. Obstruction of the bronchus supplying the distended lobe may be extrinsic (e.g., abnormal blood vessels), intraluminal (e.g., bronchial papilloma), or it may be caused by a defect of the bronchial wall (bronchomalacia). More than one lobe may be involved and sometimes the disease may be bilateral. The chest radiograph demonstrates a hyperlucent area with sparse lung markings (differentiating it from pneumothorax) and mediastinal shift. The lesion must also be differentiated from congenital diaphragmatic hernia or cystic adenomatoid malformation, which can have a similar radiologic appearance.


    Less severe forms may pass unnoticed for months or even years, and conservative management may be appropriate in some cases.


    Associated Condition




    • 1.

      Congenital heart disease—an incidence of up to 37% in reported series.



    Surgical Procedure




    • 1.

      Lobectomy (if no intraluminal or extrinsic cause can be found and corrected). This may be performed using video assisted thoracic surgery (VATS) in children other than those in extremis.



    Special Anesthesia Problems




    • 1.

      Severe respiratory failure may occur because of compression of normal lung tissue.


    • 2.

      There is the possibility of a “ball-valve” effect, which further increases the size of the affected lobe during positive-pressure ventilation.


    • 3.

      N 2 O may cause further distention of the lobe and is therefore contraindicated.


    • 4.

      Considerations for the use of VATS.



    Anesthesia Management




    • 1.

      Observe special precautions for neonates.



    Preoperative




    • 1.

      The child is cared for in the semiupright position.


    • 2.

      Give O 2 by hood. Avoid intermittent positive-pressure ventilation (IPPV) if possible (danger of “ball-valve” effect).


    • 3.

      Insert a gastric tube and apply continuous suction. This prevents gastric distention from further compromising ventilation.


    • 4.

      Check that blood is available for transfusion.


    • 5.

      Sudden serious deterioration of the child’s condition may demand immediate emergency thoracotomy to exteriorize the affected lobe and allow the normal lung tissue to ventilate.



    Perioperative




    • 1.

      Bronchoscopy to exclude intraluminal obstruction may be performed before thoracotomy or VATS.


    • 2.

      Give atropine intravenously and preoxygenate.


    • 3.

      If a bronchoscopy is planned, induce anesthesia with sevoflurane in O 2 . Otherwise, induce anesthesia with either sevoflurane or ketamine in O 2 . Spray the vocal cords with lidocaine while maintaining spontaneous ventilation. Perform laryngoscopy and intubate the trachea or pass the bronchoscope. After bronchoscopy, change to a tracheal tube.


    • 4.

      Maintain anesthesia with either sevoflurane or ketamine in O 2 with spontaneous ventilation. If assisted ventilation is required this should be applied very gently.


    • 5.

      VATS can usually be managed with a tracheal tube and gentle positive pressure ventilation during inflation of the thorax with CO 2 . Rarely is there a need to isolate the lung. In such instances consider:



      • a.

        Selective endobronchial intubation by advancing the tracheal tube into the bronchus of the contralateral lung. FOB should be used to verify the location of the tip of the tube while the neonate is supine. Intubation of the right bronchus may occlude the right upper lobe bronchus causing desaturation. Advancing the tube into the left bronchus may be accomplished by rotating the tube 180 ° before advancing it. The tube position should always be verified after the neonate is in the decubitus position.


      • b.

        Bronchial blockers may be inserted into the affected bronchus either endoscopically or radiographically. The blocker should be small, high compliant, and its position verified. Blockers are inserted outside the tracheal tube lumen and positioned by passing a FOB through the tracheal tube and verifying the blocker location after inflation. These blockers may dislodge easily during surgery and suddenly obstruct the tracheal tube. Be prepared to deflate them should this occur.



    • 6.

      Continue with spontaneous or very gently assisted ventilation until the thorax is open or accessed. In children in extremis, the affected lobe balloons out of the chest on thoracotomy and ventilation must be controlled. If VATS is used, CO 2 will be insufflated into the affected hemithorax. Careful control of ventilation and monitoring of oxygenation during one lung ventilation is required. A high F i O 2 will likely be required. Some hypercarbia may have to be accepted during this period.


    • 7.

      A nondepolarizing neuromuscular blocking drug can be given to facilitate controlled ventilation and minimize the need for inhaled anesthetic vapors once the lobe has been controlled. The fraction of inspired oxygen (F i O 2 ) should be maintained at a level that ensures full hemoglobin saturation.


    • 8.

      After the affected lobe has been excised, the remaining lung tissue will gradually expand to fill the thorax, although a pneumothorax may remain.



    Postoperative




    • 1.

      Discontinue all anesthetic drugs and administer 100% O 2. Antagonize muscle relaxants.


    • 2.

      When the infant is wide awake, suction the tracheal tube and remove it.


    • 3.

      Place the infant in a heated incubator and supply O 2 as required to maintain Sa o 2 .


    • 4.

      A chest drain (connected to underwater drainage and suction) is required.



    Anesthesia Management—Older Children


    In approximately 10% of cases, a congenital emphysematous lobe is discovered at an older age. If surgery is planned, the children should be managed as outlined for younger children. A double lumen endotracheal tube may be used to facilitate surgery or VATS.


    Suggested Reading


  • Tobias J.D.: Anaesthesia for neonatal thoracic surgery. Best Pract Res Clin Anaesthesiol 2004; 18: pp. 303-320.
  • Means L.J., Green M.C., Bilal R.: Anesthesia for minimally invasive surgery. Semin Pediatr Surg 2004; 13: pp. 181-187.
  • Iodice F., Harban F., Walker I.: Anesthetic management of a child with bilateral congenital lobar emphysema. Paediatr Anaesth 2008; 18: pp. 340-341.



  • Congenital Diaphragmatic Hernia (CDH)


    The incidence of congenital diaphragmatic hernia is 1 in 4000 live births. There are several types: anterior through the foramen of Morgagni, posterolateral via the foramen of Bochdalek, and at the esophageal hiatus. The most common lesion is posterolateral, through the foramen of Bochdalek, usually on the left side. Herniation of abdominal contents into the thorax is associated with respiratory distress, mediastinal displacement (“dextrocardia”), and a scaphoid abdomen. Breath sounds are absent over the affected side. Bowel sounds are very rarely heard over the thorax. The radiographic appearance is usually diagnostic but may be indistinguishable from that of congenital lobar emphysema.


    In many children with CDH, both lungs may be severely hypoplastic. Currently, CDH is thought to be a primary failure of lung development associated with a failure of diaphragm development.


    The infant with CDH is usually in severe respiratory distress at or soon after birth. In recent years, the diagnosis has generally been made antenatally by fetal ultrasound.


    Associated Conditions




    • 1.

      Malrotation of the gut (40% of cases)


    • 2.

      Congenital heart disease (15%)


    • 3.

      Renal abnormalities (less common)


    • 4.

      Neurologic abnormalities


    • 5.

      Cantrell’s pentalogy (defined as CDH, omphalocele, sternal cleft, ectopia cordis, and intracardiac defect (VSD or diverticulum of left ventricle)



    Surgical Procedure




    • 1.

      Reduction of the hernia and repair of the diaphragmatic defect: usually a transabdominal procedure—often performed via the laparoscope.



    Special Anesthesia Problems




    • 1.

      Optimal preoperative preparation of the child: The trend in recent years is not to rush to surgery. Relief of compression of the lungs by reduction of the herniated abdominal viscera usually does not solve the problem; indeed, there is evidence that respiratory mechanics and hemodynamics are worse postoperatively. It is now preferred to treat the respiratory insufficiency by muscle paralysis, controlled gentle ventilation, and therapy to reduce pulmonary vasoconstriction (including surfactant, hyperventilation, oxygenation, correction of metabolic acidosis, anesthesia and paralysis, and nitric oxide). If these measures fail, ECMO may be instituted. Surgical correction is performed later, as an elective procedure, when the infant is improving and can be weaned from respiratory support.



    Anesthesia Management


    Preoperative


    Preoperative management requires the facilities and trained staff of a specialist unit. The infant is nursed in a semiupright, semilateral position, facing toward the involved side. A gastric tube is passed and maintained on low suction to prevent further distention of intrathoracic abdominal viscera. All but the exceptionally fit older infant require intubation and ventilation: Bag-mask ventilation should be avoided because it may further distend the stomach and increase respiratory distress.



    • 1.

      Muscle paralysis after intubation facilitates controlled ventilation and minimizes struggling, thereby decreasing the O 2 demand. It also reduces airway pressure, minimizes further lung damage, and diminishes the ever-present danger of pneumothorax. (Pneumothorax is a constant danger and must be watched for and immediately treated.)


    • 2.

      Ventilation should be gentle—not to exceed positive inspiratory pressures of 20 cm H 2 O. Some degree of hypercapnia may have to be accepted rather than using high pressure that might cause further damage to the hypoplastic lungs.


    • 3.

      High-frequency ventilation may be applied to facilitate gas exchange while minimizing pressure swings, which might cause further lung damage. Surfactant therapy may be administered to preterm infants with CDH.


    • 4.

      Pulmonary vascular resistance may be reduced by general measures such as fentanyl infusion and minimal handling of the child. Nitric oxide may be administered by inhalation and may further reduce pulmonary vascular resistance in some children although the results of NO in CDH children are unimpressive.


    • 5.

      When all of these measures fail, ECMO is indicated and may permit survival of some children until the pulmonary status improves.



    Aggressive invasive monitoring using arterial pressure and ECHO-derived pulmonary artery pressures is required to ensure optimal treatment for the pulmonary status. The best predictors of the degree of pulmonary hypoplasia, and hence of survival, are the PaCO 2 and the respiratory index (the product of mean airway pressure and respiratory rate). Those children who are easy to ventilate and not grossly hypercarbic have a better prognosis. Those who are hypercarbic and hypoxic with a high mean airway pressure are less likely to survive. ECMO may increase survival of this latter group. If the child improves on ECMO, surgery is usually performed just before weaning.


    Perioperative


    CDH may be repaired in the NICU or in the OR. Children on ECMO and HFOV and those who have circulatory instability often undergo surgery in the NICU; most surgeons prefer to transport all other children to the OR for surgery.



    • 1.

      Induce and maintain anesthesia with IV fentanyl. Ventilate with isoflurane as tolerated and O 2 /air to maintain SaO 2 . N 2 O is avoided as it could further distend gas-containing herniated viscera.


    • 2.

      Monitor airway pressure. This should not exceed 20 cm H 2 O (greater pressures may cause further lung damage or contralateral pneumothorax).


    • 3.

      Do not try to expand the lungs after reduction of the hernia (lung damage may result).


    • 4.

      Monitor blood gas and acid-base status frequently and correct as indicated.



    For children having surgery on ECMO:



    • 1.

      Common practice has been to administer additional doses of relaxant and opioids. However, very often infants on ECMO develop tolerance to fentanyl and require very large doses to blunt the cardiovascular response to surgery. Instead, low concentrations of isoflurane may be titrated to blunt the responses by adding it to the oxygenator gas supply.


    • 2.

      Ensure ECMO cannulas do not become kinked during positioning for surgery.


    • 3.

      Even though the child may be heparinized, excessive bleeding usually is not a problem.



    Postoperative




    • 1.

      Return the child to the intensive care unit (ICU) for continued intensive respiratory care.


    • 2.

      Some infants who have been salvaged by heroic intensive care measures may remain oxygen-dependent for years.



    Suggested Reading


  • Robinson P.D., Fitzgerald D.A.: Congenital diaphragmatic hernia. Paed Resp Rev 2007; 8: pp. 323-335.
  • Becmeur F., Reinberg O., Dimitriu C., et. al.: Thoracoscopic repair of congenital diaphragmatic hernia in children. Semin Pediatr Surg 2007; 16: pp. 238-244.



  • Tracheoesophageal Fistula and Esophageal Atresia


    Tracheoesophageal fistula and esophageal atresia, interrelated conditions, may occur in several combinations. The overall incidence is 1 in 3000 live births. Maternal polyhydramnios is present, and premature birth is common.


    The most common form (approximately 90% of cases) is esophageal atresia with a fistula between the trachea and the distal segment of the esophagus ( Figure 13-1 , Type 1). This condition might be detected when the neonate chokes at the first feeding, but ideally it should be diagnosed antenatally by ultrasound or at birth by the inability to pass a soft rubber catheter into the stomach. Plain radiography confirms the diagnosis, showing the catheter curled in the upper esophageal pouch and an air bubble in the stomach, indicating a fistula. Contrast medium should not be used because it may be aspirated and further damage the lungs.




    Figure 13-1


    Esophageal atresia and tracheoesophageal fistula (see text for details).


    Esophageal atresia without fistula is the second most common form of the disease ( Figure 13-1 , Type 2); there may be a large gap between the upper and lower segments of the esophagus. In such children, it is not possible to pass a catheter into the stomach, and there is no gastric air bubble. Aspiration from the upper pouch is an immediate danger. Constant suctioning of the upper pouch should be instituted pending surgical repair.


    The third most common form is the H-type fistula without atresia ( Figure 13-1 , Type 3); diagnosis of this type may be more difficult and is often delayed. In such cases, there is usually a history of repeated respiratory infections. The fistula may be difficult to locate even when contrast studies and endoscopy are used. Once the fistula is identified, surgical ligation often can be performed via a neck dissection.


    There are other, rarer anatomic variants of this disease, many of which include tracheal stenosis.


    Associated Conditions




    • 1.

      Prematurity (30% to 40%)


    • 2.

      Congenital heart disease (22%)


    • 3.

      Additional gastrointestinal abnormalities (e.g., pyloric stenosis)


    • 4.

      Renal and genitourinary abnormalities


    • 5.

      The VACTERL association: VATER association ( V ertebral defects, A nal atresia, T racheoesophageal fistula, E sophageal atresia, R adial and R enal dysplasia) with added C ardiac and L imb defects


    • 6.

      Tracheomalacia and other abnormalities of the trachea (e.g., stenosis)



    Surgical Procedures


    The infant’s general condition and the anatomy of the defect govern the choice of surgical management:



    • 1.

      Primary complete repair (ligation of fistula and esophageal anastomosis), which is preferred


    • 2.

      Staged repair (gastrostomy followed by division of the fistula, followed later by repair of the esophagus)



    The current surgical trend is to perform early primary repair. Often the operation is preceded by bronchoscopy to define the site of the fistula and exclude other tracheal defects.


    Special Anesthesia Problems




    • 1.

      Prematurity and other associated diseases (congenital heart disease is common) may complicate the case.


    • 2.

      Pulmonary complications secondary to aspiration may be present.


    • 3.

      There is a possibility of intubating the fistula.


    • 4.

      Anesthetic gases may inflate the stomach via the fistula.


    • 5.

      Surgical retraction during repair may obstruct ventilation.


    • 6.

      Subglottic or tracheal stenosis may be present.



    Anesthesia Management—Primary Repair




    • 1.

      Observe special precautions for neonates.



    Preoperative




    • 1.

      The infant is nursed in a semiupright position.


    • 2.

      The proximal esophageal pouch is suctioned continuously to prevent aspiration of secretions.


    • 3.

      Institute intensive respiratory care to reduce pulmonary complications. (Even so, the lung condition seldom improves until after ligation of the fistula; therefore surgery should not be delayed in the hope that pulmonary status will markedly improve.)


    • 4.

      Examination of the infant to detect other associated lesions should be completed (i.e., echocardiography to rule out a congenital heart defect).


    • 5.

      Establish a reliable intravenous route and ensure that blood is available for transfusion.


    • 6.

      Give maintenance fluids intravenously, but bear in mind that dehydration is not a major problem; neonatal fluid requirements are low during the first 24 hours, and fluid and electrolyte depletion does not occur with esophageal obstruction.


    • 7.

      In the preterm infant with RDS and poor lung compliance, there is a danger of massive distention of the stomach (or massive leak from a gastrostomy if present) and consequent failure to ventilate. Rupture of the stomach and pneumoperitoneum may occur. The risk of massive gastric distention in infants with RDS has disappeared since the introduction of surfactant therapy. It has been suggested that a gas leak through the fistula may be controlled by one of:



      • a.

        A balloon catheter passed via a gastrostomy into the lower esophagus.


      • b.

        A balloon catheter inserted into the fistula under bronchoscopic guidance.


      • c.

        Most commonly by early simple ligation of the fistula in infants with RDS who develop high airway pressures. The operation is brief and can be followed by esophageal reconstruction after the child’s respiratory function has improved.



    • 8.

      Beware of the possibility of subglottic stenosis; have small tube sizes available.


    • 9.

      TEF may be repaired using VATS in which case the considerations of one-lung surgery must be observed.



    Perioperative




    • 1.

      Suction the upper pouch. Apply lidocaine 4% to the gums and palate using a gauze sponge; this lessens the response to intubation.


    • 2.

      Apply the usual monitors and prepare to monitor ventilation using a precordial stethoscope in the left midaxillary line.


    • 3.

      One of two approaches may be taken to secure the airway:



      • a.

        Induce anesthesia with sevoflurane or halothane in O 2 , maintaining spontaneous ventilation. Perform laryngoscopy and spray the larynx with lidocaine (maximum dose, 5 mg/kg). Return to the mask and continue sevoflurane anesthesia for 2 or 3 minutes.


      • b.

        Alternately, and if a bronchoscopy is not planned, sedate with fentanyl (0.5 to 1 µg/kg) and midazolam (25 µg/kg) and spray the larynx with lidocaine.



      Then:



      • a.

        Intubate the trachea with the bevel of the tube facing posteriorly (to avoid intubating the fistula).


      • b.

        Alternately, if a rigid bronchoscopy is planned, once the surgeon passes the bronchoscope, attach the anesthesia circuit to the side arm of the bronchoscope and continue with spontaneous or gently assisted ventilation. When the bronchoscopy is completed, insert a tracheal tube with the bevel facing posteriorly, or


      • c.

        If a fiberoptic bronchoscopy is planned, insert the tracheal tube with the bevel posterior and attach a bronchoscopic adapter to accommodate the fiberoptic bronchoscope. Gently assist ventilation while the endoscopy proceeds.



    • 4.

      Immediately after intubation, check ventilation throughout the lung fields. If ventilation is unsatisfactory , remove the tube, give O 2 , and reinsert the tube. It is advantageous to place the tube with its tip just above the carina; this can be done by advancing the tube into the bronchus and then withdrawing it until bilateral ventilation is heard. This should place the tip of the tube below the fistula in most cases, although in some children the fistula lies at the level of the carina. At this time, the tube should be rotated so that the bevel faces anteriorly (to prevent inflating the fistula). More complicated methods to position the tube have been described but are unnecessary in our experience. Always check ventilation again after positioning of the child is complete. It is preferable to use a tube without a “Murphy eye,” to minimize the possibility of leaks via the fistula.


    • 5.

      Once the tube has been properly placed, oxygenate and perform tracheobronchial suction to remove any accumulated secretions before the surgery commences.


    • 6.

      Maintain anesthesia with air, O 2 , and sevoflurane or isoflurane with spontaneous or gently assisted ventilation. If the inhalational anesthetic is not tolerated, small doses of fentanyl should be substituted (up to 10 to 12 μg/kg).


    • 7.

      If spontaneous ventilation is inadequate: assist ventilation cautiously, while observing and auscultating over the stomach for inflation. If gastric inflation occurs, allow the child to breathe spontaneously (with gentle manual assistance) until the fistula is ligated.


    • 8.

      Monitor ventilation carefully during surgical manipulation: large airways may be kinked by retraction, especially as the fistula is manipulated.


    • 9.

      Once the fistula is ligated, give a muscle relaxant and control the ventilation in the usual manner.


    • 10.

      Reports suggest that VATS may be useful in the repair of TEF, the view on the video-screen allows very precise repair of the esophagus. In this case, it may not be necessary to advance the endotracheal tube into the bronchus to continue with one lung anesthesia. As the surgeon insufflates CO 2 under 5 cm/H 2 O pressure, the “up” lung is compressed and the lesion visualized, in effect, obtaining one-lung anesthesia by increasing intrathoracic pressure. During this period, ventilation may become difficult and a high F i O 2 required. Avoiding the necessity to intubate the bronchus may be advantageous as persistent upper lobe atelectasis may occur after endobronchial intubation.



    Postoperative




    • 1.

      The child with a clear chest who is awake and moving vigorously should be extubated in the OR. Some surgeons, however, may prefer to keep the trachea intubated and a gastroesophageal tube in place for several days to avoid reintubation and damage to the tracheal repair.


    • 2.

      If there are pulmonary complications or any doubts about the adequacy of ventilation, continue controlled ventilation.


    • 3.

      The pharynx is suctioned with a soft catheter that has a suitable maximum length of insertion clearly marked; it must not reach (and damage) the anastomotic site.


    • 4.

      Prolonged intensive respiratory care may be required. (Swallowing is not normal postoperatively and aspiration may occur.)


    • 5.

      Prognosis after the repair depends on the maturity of the infant, whether other congenital anomalies are present, and whether pulmonary complications develop. In the absence of these conditions, the prognosis is excellent.


    • 6.

      Postoperative analgesia may be provided by a caudal epidural catheter inserted intraoperatively and threaded to the thoracic level; careful management of local anesthetic doses is required (see Chapter 5, page 156 ).



    Anesthesia Management-Staged Repair


    If staged repair is planned, a preliminary gastrostomy is performed under local or general anesthesia. Management of the second stage (ligation of the fistula) should follow the sequence outlined for primary repair. Further surgery (to repair the atresia) may be done later, when the child’s condition is optimal.


    Late Complications




    • 1.

      Diverticulum of the trachea, at the site of the old fistula, is common in children who had a tracheoesophageal fistula repaired during infancy. Be aware of this possibility and the danger of intubating the diverticulum during anesthesia in later life.


    • 2.

      The tracheal cartilage structure is abnormal, and tracheomalacia may cause symptoms during infancy after repair of a tracheoesophageal fistula. Episodes of stridor, dyspnea, and cyanosis (“dying spells”) characteristically occur during feeding. This is caused by compression of the soft trachea between the dilated esophagus and the arch of the aorta. Severe symptoms require surgical treatment by aortopexy or tracheoplasty with an external splint. These children often have a deep barking cough much like children with croup.


    • 3.

      Stricture may develop at the site of the esophageal anastomosis with episodes of esophageal obstruction with food (the hotdog in the esophagus); it may require repeated dilations and, later, possibly resection with replacement, using the colon or a gastric tube.



    Suggested Reading


  • Goyal A., Jones M.O., Couriel J.M., et. al.: Oesophageal atresia and tracheo-oesophageal fistula. Arch Dis Child Fetal Neo Ed 2006; 91: pp. F381-F384.
  • Naik-Mathuria B., Olutoye O.O.: Foregut abnormalities. Surg Clin N Am 2006; 86: pp. 261-284.
  • Krosnar S., Baxter A.: Thoracoscopic repair of esophageal atresia with tracheoesophageal fistula: anesthetic and intensive care management of a series of eight neonates. Paediatr Anaesth 2005; 15: pp. 541-546.
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    Mar 27, 2019 | Posted by in ANESTHESIA | Comments Off on General and Thoracoabdominal Surgery
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