The unpleasant times of years gone by when surgeons and anesthesiologists found themselves in conflict over competing perceptions of their respective importance and relevance are hopefully consigned to the past. Today, interdisciplinary collaboration and close cooperation are critical to ensuring that all patients are provided with the best practice and levels of care. This is particularly true when treating low-weight prematures or performing minimally invasive procedures in the thoracic cavity. In the following chapter, Christian Seefelder focuses not only on appropriate procedures and techniques, but also on perioperative pain management.

The advances in pediatric surgery have resulted in the desire by the pediatric surgeon, by families and by medical consultants for earlier, more definitive, often video-assisted, “minimally invasive” surgery in younger and sicker patients than a decade ago. Anesthesia care for small, young and sick patients may have become safer more through better understanding, improved monitoring and more courage than through improvements in drugs, advances in technology or innovation in management. Pediatric anesthesiologists need intimate knowledge and understanding of the (congenital) surgical lesion and its pathophysiology, of the associated medical disorders and of the surgical procedure. In turn, pediatric surgeons need knowledge and understanding of the anesthetic techniques, concerns and limitations such as neurotoxicity of anesthesia in neonates, infants and young children, the difficulty of lung isolation in small patients or the physiologic challenges of minimally invasive surgery in pediatric patients.

Solid data from animal models suggest that exposure of neonatal animals to agents used in human anesthesia results in accelerated or premature neuroapoptosis and neurodevelopmental disadvantages. Common criticism of these studies includes the difficulty extrapolating from animal data to humans, difficulty comparing doses required for animals and humans, difficulty comparing animal outcomes to human outcomes, difficulty excluding the effect of disease and surgery requiring anesthesia on neurodevelopment and impossibility of providing necessary surgery without anesthesia. At the same time, suspicion has been brought forward that it is less the anesthetic agent than the physiologic milieu created that may be responsible for the changes (i.e. hypotension, desaturation). A clear recommendation regarding a safe or advantageous general anesthetic technique or agent is missing, but dexmedetomidine may be less detrimental than other anesthetic agents in regards to neurotoxicity.

1.2.1.2Human data

While thoracic surgery is performed under general anesthesia, there is often a misunderstanding by patients, families, medical specialists and surgeons about the degree of sedation for other studies and procedures. Not uncommonly, it has been agreed upon that a procedure can be done “under local” or “light sedation”, but at the same time the patient has been promised to be “asleep” and the surgeon or radiologist expects the patient to be “not moving”.

Few children are interested in being awake and aware and in lying still for procedures or studies. Small infants can sometimes be fed and bundled up and sleep through non-stimulating studies such as MRI. Distraction and entertainment with videos can be offered and parents can be present for reassurance for older children to undergo unsedated imaging studies or procedures such as lumbar puncture, bone marrow aspirate or central line placement under topical or local anesthesia.

For adequate surgical conditions and for imaging studies requiring immobility, deep sedation or general anesthesia are necessary; while spontaneous respirations may be maintained, concerns are progression to apnea, loss of protective airway reflexes, increasing airway obstruction and hemodynamic compromise.

The typical evaluation and workup will include all aspects of the history and physical exam, with focus on the thoracic pathology in question, specifically any respiratory symptoms and distress, stridor and any signs or symptoms indicating difficult airway management or risk of respiratory obstruction during anesthesia and surgery. Most studies will have been ordered by surgeons and pediatric specialists but should be reviewed by the pediatric anesthesiologist, including chest x-ray, computed tomography (CT), magnetic resonance imaging (MRI), angiograms, ventilation/perfusion scans, cardiologic studies, lung function tests, laboratory results, cultures and biopsies. Of particular importance is consultation with other pediatric specialists such as pediatric pulmonologists, cardiologists, hematologists, oncologists, endocrinologists and radiologists to optimize preoperative workup, evaluation, management and communication.

Especially in younger children with limited cooperation, many types of studies such as lung function tests may not be possible at all. Others such as CTs, MRIs, angiographies or biopsies will require the involvement of the anesthesiologist for sedation or anesthesia. To provide the patient with a safe anesthetic and a satisfactory study, requesting service, surgeon, radiologist and anesthesiologist should communicate before the study to understand each other’s concerns and objectives. While case to case assessment and discussion are important, agreeing on a protocol across departments allows input from all specialties ahead of time and decreases case to case confrontation. Protocols appear reasonable for imaging studies in patients with anterior mediastinal masses or tracheomalacia. Early involvement has the advantage of familiarizing the anesthesiologist with the patient’s airway anatomy and management and physiologic response to anesthesia prior to major thoracic surgery.

Standard monitoring includes electrocardiogram (ECG), non-invasive blood pressure (NIBP), pulse oximetry, patient temperature, inspiratory oxygen concentration (FiO2) and end-tidal CO2 concentration (ETCO2). It may be difficult to establish all monitors prior to induction in children.

Invasive arterial monitoring allows arterial blood gas sampling and immediate recognition of hemodynamic effects of surgical retraction, mechanical arrhythmias or air embolism. It is indicated in lobectomy or pneumonectomy, in thoracic tumor resections, major neonatal thoracic surgery for congenital diaphragmatic hernia or TEF repair, in infant thoracoscopy or for the patient’s general medical condition. Lung isolation in itself is not an indication for placement of an arterial catheter, and it may not be necessary for simple lung wedge resections or biopsies, thoracoscopic pleurodesis or pectus repair. Risks include ischemic complications from local skin necrosis to loss of an extremity. Placement aids for small patients are transillumination, Doppler and more recently ultrasound.

Pulse oximeters, arterial catheter and blood pressure cuff are distributed over several extremities. In neonates, pre- (right arm) and post-ductal (lower extremity) oxygen saturation should be monitored to detect right to left shunting across the ductus arteriosus. Electroencephalographic monitors are available for anesthetic depth, seizure and ischemia monitoring. Transesophageal echocardiography is available for children, non-invasive cardiac output monitors are being evaluated, pulmonary arterial catheters are used less commonly in the pediatric population.

Cerebral blood flow can be monitored via transcranial Doppler, and near-infrared spectroscopy (NIRS) measures brain oxygenation. In particular cerebral or somatic tissue oxygenation monitoring is rapidly gaining importance and popularity, since hemodynamic parameters alone do not reflect actual end organ supply. Intraoperative decreases of regional brain oxygenation must be responded to promptly by improving hemodynamics and cerebrovascular perfusion but also by correcting surgical maneuvers such as retraction, increased intrathoracic pressure or hypercarbia from CO2 insufflation.

The Univent™ Inoue tube from Fuji has a channel for a bronchial blocker incorporated into the wall of the tube. Even though pediatric sizes are available, they appear to have an unfavorable ratio between inner and outer diameters: the “3.5 ID” uncuffed tube has a 7.5–8 mm outer diameter, the “4.5 ID” cuffed tube 8.5–9 mm. These tubes therefore are only suitable for older children and adolescents.

Lastly, if lung separation is necessary but technically not possible, the use of ECMO or cardiopulmonary bypass has been reported, for example for whole lung lavage in infants and small children.

1.2.6.1Surgical capnothorax

Decompression of the non-ventilated lung in main stem intubation and with bronchial blockers may be slow. Use of 100% oxygen or oxygen/ nitrous oxide prior to isolation rather than oxygen/air accelerates lung collapse through the faster absorption of oxygen and nitrous oxide than nitrogen from the non-ventilated lung.

Pressure control ventilation is preferred over volume control ventilation to optimize tidal volumes while limiting ventilation pressures. Peak inspiratory pressures (PIPs) are chosen to achieve a desirable tidal volume of 5–8 ml/kg. Especially with the use of bronchial blockers, PIPs should be limited due to the risk of exceeding balloon seal and trapping ventilation in the non-ventilated lung. Positive end expiratory pressure (PEEP) of 3 to 5 cm H2O helps to reduce the risk of atelectasis in the dependent/ventilated lung due to positioning, surgical compression and capnothorax.

Intraoperative hypercarbia is managed with limited increase in tidal volume by increasing peak inspiratory pressure or inspiratory time, and by increasing respiratory rate. Minimizing dead space and using low-compliance circuits may prove beneficial. Intraoperative flexible fiberoptic bronchoscopy, for example during tracheopexy, increases resistance to ventilation and may need to be limited if hypercarbia is difficult to manage. If CO2 elimination by ventilation is difficult, avoiding patient hyperthermia helps limiting endogenous CO2 production from increased patient metabolism. As CO2 insufflation into the pleural cavity by the surgeon is the major contributor of hypercarbia during thoracoscopy, limiting insufflation pressures or avoiding insufflation is the best option to reduce hypercarbia.

In the absence of other contraindications to hypercarbia such as pulmonary hypertension or need for low pulmonary vascular resistance (Fontan circulation), some degree of temporary permissive hypercarbia may be reasonable and tolerated, but the degree of acceptable hypercarbia remains undefined. paCO2 below 50 mm Hg is likely unproblematic and up to 60 mm Hg probably acceptable. It is important to correlate endtidal CO2 with paCO2 to be able to track changes.

Intraoperative desaturation in pediatric thoracic anesthesia is managed similar to adults. Inspiratory oxygen concentration is increased and normoventilation is attempted. Lateral positioning, padding, surgical retraction and pressure may result in intraoperative atelectasis of the ventilated dependent lung and contribute to pulmonary desaturation. Gentle recruitment breaths can be attempted remembering the possible loss of lung isolation when bronchial blockers or main stem intubation are used and the ventilation pressures exceed the cuff pressure. PEEP is added to the dependent lung or increased. Secretions or blood may block the airway. However, suctioning any pediatric endotracheal tube and in particular suctioning during one lung ventilation may result in rapid desaturation, which may be slow to recover. Double lumen tubes and some bronchial blockers allow upper-lung CPAP (continuous positive airway pressure) and recovery of oxygenation albeit at the price of a distended lung which may not please the surgeon. Nitric oxide may improve ventilation/ perfusion matching of the dependent lung. Changing the anesthetic to an intravenous technique supports HPV in adults. Finally, clamping of the pulmonary artery, especially when lobectomy or pneumonectomy are performed, (temporarily) aborting one lung ventilation, and considering ECMO or cardiopulmonary bypass would restore oxygenation.

1.2.7.1Congenital lung lesions in neonates and infants

These lesions can overlap and are congenital pulmonary airway malformation (CPAM, connected to the airway), including previously termed congenital cystic adenomatoid malformation (CCAM), pulmonary sequestration (PS, not connected to the airway, systemic blood supply), congenital lobar emphysema (CLE, connected to the airway with large bullae), bronchogenic and enteric duplication cysts (cysts not connected to the airway).

Expanding lesions in the neonate

Stable lesions

Tracheo-esophageal fistula (TEF)

Patients with pure EA (gas free abdomen) can be subjected to positive pressure ventilation as necessary. In the presence of a TEF, the abdomen is gas filled and pronounced gastric distention may exist, if positive pressure ventilation was performed during neonatal resuscitation. The patient should not be intubated electively preoperatively, spontaneous respirations should be maintained as long as possible. Positive pressure ventilation during anesthetic management can similarly distend the stomach, impair diaphragmatic excursion, limit ventilation and result in hypercarbia and desaturation. Management varies by institution, and anesthesiologist and surgeon should discuss their plans preoperatively.