Anesthesiology

Congenital Lobar Emphysema

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What the Anesthesiologist Should Know before the Operative Procedure

Tachypnea, cyanosis, retractions, and oxygen desaturation reflect the mass effect of intrathoracic air trapping in congenital lobar emphysema on pulmonary and cardiac function. Positive pressure ventilation and nitrous oxide may exacerbate the patient's clinical condition.

Diagnosis is usually made soon after birth, with 33% of patients presenting in the first several hours of life and 50% of patients by 1 month of age. Only 5% of individuals present after 6 months. A male predilection exists. Prenatal diagnosis by ultrasound and MRI has also been made though a postnatal chest radiograph is needed to see the extent of air trapping. Affecting upper lobes preferentially, particularly the left upper lobe, the pathology is thought to be caused by extrinsic or intrinsic lobar bronchial obstruction.

Although the exact cause is unknown in 50% of the cases, air trapping is thought be caused by dysplastic bronchial cartilages causing a ball valve obstruction, endobronchial obstruction from inspissated mucus or mucosal proliferation, extrinsic obstruction from aberrant vasculature or mass, or diffuse bronchial abnormalities from infection. Most patients have a normal number of alveoli that are overinflated though a variant exists with enlargement of the lobe caused by an increase in alveolar.

1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

Severe respiratory compromise though the least common presentation of congenital lobar emphysema usually indicates a need for emergent surgery. Worsening symptoms indicate further air trapping, right heart failure, pulmonary hypertension, and impending arrest.

Emergent: Neonates and infants with severe respiratory compromise often have a degree of right heart failure and pulmonary hypertension making the induction and maintenance of anesthesia even more dangerous. Minimizing respiratory and cardiac depression while trying to maintain spontaneous ventilation is key.

Urgent: Mildly tachypneic infants can worsen dramatically on the induction of anesthesia with increased air trapping and intrathoracic mass effect. Spontaneous ventilation, if possible, is preferable until the thoracotomy is performed.

Elective: Asymptomatic infants though less likely may air trap and worsen with the induction of anesthesia. Spontaneous ventilation is again desirable.

2. Preoperative evaluation

After evaluating evidence of respiratory failure, assessment of the degree of pulmonary hypertension and right heart failure will aid in the design of the anesthetic management plan. Since 14% of infants with congenital lobar emphysema also have congenital heart disease, examination of the structure of the heart is pertinent. Other congenital abnormalities have been associated with congenital lobar emphysema, including diaphragmatic hernia, chondroectodermal dysplasia, chondrodystrophy, cleft palate, and aplastic kidney. Concurrent appraisal of these conditions may be warranted depending on the symptoms.

Medically unstable conditions warranting further evaluation include impending arrest due to severe respiratory and cardiac failure or severe pulmonary hypertension may warrant placing the infant on ECMO as a temporizing and stabilizing technique.

Delaying surgery may be indicated if a child whose respiratory compromise is minimal may benefit by observation and careful surveillance to allow resolution of transient pulmonary hypertension issues of the newborn, stabilization of other associated congenital issues, and an increase in the size and age of the baby.

3. What are the implications of co-existing disease on perioperative care?

Perioperative evaluation

Following a detailed physical examination highlighting an evaluation of the airway, respiratory, and cardiovascular system, assessment of any respiratory support, including oxygen supplementation and ventilatory and cardiovascular support is mandatory. Review of a chest X-ray will reveal the size and location of the emphysematous lobe as well as impingement on the mediastinum. In the immediate postnatal period, the abnormal lobe may appear consolidated but usually quickly appears hyperlucent with pulmonary vasculature markings. A similar review of prenatal ultrasounds, if available, may provide confirmatory information and information about the rest of the lung, possibly compressed postnatally. An ultrafast CT and/or MRI will further define the lesion and extent of mediastinal impingement. An echocardiogram provides structural and functional information about the heart.

With significant mediastinal impingement, cardiac function may be significantly decreased secondary to preload and afterload effects of the mediastinal shift. Valvular regurgitation in the right heart and bowing of the septum might indicate significant pulmonary hypertension. A ventilation/perfusion scan confirms the extent of the lesion though may only be necessary in unclear cases where other pulmonary lesions might be present. Arterial blood gases, if available, may quantitatively aid in the assessment of respiratory compromise.

Review of hemoglobin, BUN, creatinine, and calcium provide baseline assessments of hematologic and renal systems. Outside of the neonatal period, a growth curve will provide an assessment of the effect of respiratory dysfunction on the child's nutritional status with a normal growth curve likely representing mild respiratory disease and an abnormal curve typifying significant disease.

Perioperative risk reduction strategies

In the extreme case, ECMO preparedness or possibly preoperative ECMO institution may be considered. ECMO may allow concomitant pulmonary hypertension to abate or decrease. Although not without issues like significant bleeding, surgery could proceed with the infant on ECMO if there was concern about postoperative pulmonary failure due to the extent of the lesion. Having ECMO available postoperative as a rescue strategy may also be useful.

Discussion and institution of single-lung ventilation, although difficult in the small baby, may also facilitate thoracoscopic resection, if planned, and ventilation of normal lung. Availability of high-frequency ventilation may allow the use of small tidal volume ventilation to minimize further expansion of the emphysematous lobe.

b. Cardiovascular system:

Acute/unstable conditions

If the emphysematous lobe affects the mediastinum by increasing afterload, impinging on cardiac contractility and decreasing preload, heart function can be severely compromised though it usually dramatically improves with the thoracotomy. Cardiac inotropes, like dopamine and epinephrine, and repeated fluid boluses may be needed preoperatively to improve heart function.

c. Pulmonary:

Nitric oxide administration may be useful in the infant or child with pulmonary hypertension as the result of slow changes in the transitional circulation or from effects of the mass on pulmonary circulation. Preoperative single lung ventilation may limit the overexpansion of the emphysematous lobe in the severely affected infant.

d. Renal-GI:

N/A

e. Neurologic:

N/A

f. Endocrine:

N/A

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the anesthetic plan (e.g., musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

N/A

4. What are the patient's medications and how should they be managed in the perioperative period?

N/A

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

N/A

i. What should be recommended with regard to continuation of medications taken chronically?

N/A

j. How to modify care for patients with known allergies

N/A

k. Latex allergy - If the patient has a sensitivity to latex (e.g., rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.

N/A

l. Does the patient have any antibiotic allergies - Common antibiotic allergies and alternative antibiotics

N/A

m. Does the patient have a history of allergy to anesthesia?

Malignant hyperthermia (MH)

Documented: Avoid all trigger agents such as succinylcholine and inhalational agents. Follow a proposed general anesthetic plan: total intravenous anesthesia with propofol ± opioid infusion ± nitrous oxide. Ensure that an MH cart is available [MH protocol].

5. What laboratory tests should be obtained and has everything been reviewed?

The severity of the clinical condition may limit the preoperative laboratory evaluation. In the baby with severe pulmonary compromise, a chest X-ray identifying the pathological condition may be the only test easily obtained. Echocardiograms will allow qualification of cardiac function as well as structural abnormalities. The hypolucency of the emphysematous lobe may make good cardiac windows difficult to obtain. High-speed CT and MRI will provide further definition of the surgical lesion to the surgeon and anesthesiologist. In the very stable patient, ventilation/perfusion scans will further define the anatomy.

Measurement of a hemoglobin and an active type and cross for blood are necessary. In the severely dyspneic child, an arterial blood gas will confirm the extent of the disease and provide a measure of adequacy of ventilation.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

Intrathoracic surgery in infants and children requires general endotracheal anesthesia. Ideally, maintenance of spontaneous ventilation is desirable prior to chest wall incision to prevent additional expansion of the emphysematous lobe. The addition of a caudal epidural in infants or thoracic epidural in older children may aid in the control of pain postoperatively if a thoracotomy is performed as well as decreasing the intensity of a general anesthetic necessary.

For thoracoscopic surgical approaches, one-lung ventilation may be a surgical requirement, although sometimes difficult to achieve in small infants. One-lung ventilation may also occasionally improve ventilation with in patients having open thoracotomies.

Regional anesthesia

Epidural analgesia, as a supplement rather than primary technique in an open thoracotomy, may permit the use of less opioids and volatile anesthetic as well as help in postoperative pain control. Earlier extubation from less systemic depressants may be possible. In children under 2 years of age, the caudal approach allows easier access to the epidural space though thoracic positioning of the tip may require fluoroscopy or the use of other techniques to document placement.

In small infants, the quantity and concentration of local anesthetic used are limited by toxicity concerns. Concentration of local anesthetic to achieve the desired intensity of nerve block must be weighed against the volume needed to achieve the necessary spread. Because of the location of their insertion, caudal catheter insertion sites are difficult to keep clean for prolonged times unless tunneled away from the sacral hiatus.

6. What is the author's preferred method of anesthesia technique and why?

If surgery is necessary in the neonatal period, respiratory failure is likely a key feature of the infant’s condition. Intubation in the nursery is likely with concomitant insertion of an umbilical arterial line. Following transport to a warmed, operating room and application of usual monitors, the infant should be placed on a forced warm-air device and covered with plastic where possible to maintain body temperature. Overhead warming lights should be used to maintain temperature as the baby is prepared for surgery. Two avenues of venous access should be obtained to permit glucose administration in independent of fluid and medication administration. An umbilical venous catheter could be used as one intravenous system. A fluid-warming system should be charged so that blood can be immediately administered.

Resuscitationdrugs including calcium gluconate and epinephrine as well as dopamineand epinephrine infusions should be ready as precalculated doses orinfusions. Prechecked recently packed or washed red cells or whole bloodshould be in the room ready for administration. Point of care glucose,hemoglobin, and arterial blood gas devices should be ready in the roomor plans for rapid transport to a laboratory should be in place.Equipment and expertise to administer nitric oxide should be readilyavailable. Intravenous infusions should be carefully inspected and airshould be removed because of the frequency of accompanying congenitalheart disease and possibility of an open ductus arteriosus.

Prior to pleura incision, spontaneous ventilation should be maintained, if possible. Assisted ventilation with small tidal volumes and low inspiratory pressures may be required. Anesthesia should be induced with volatile anesthesia and a small dose of fentanyl (1-2 mcg/kg). If the infant is not already receiving antibiotics, then prophylactic antibiotics (cefazolin) should be administered prior to the incision. Since a rise in glucose is often seen with surgical incision, preexisting glucose infusions should be decreased. Intravenous infusion rates should be minimized to permit precise control of fluid administration.

Hypotension should be addressed with small volume infusions (5-10 mL/kg) of saline or blood or a dopamine infusion (5-20 mcg/kg/min), depending on fluid status and believed etiology of low pressure. A rigid bronchoscopy is often performed prior to a thoracic incision to further clarify the lesion. Lidocaine (1-2 mg/kg diluted in a 2-3 mL of saline), sprayed by the surgeon, through the bronchoscope on the vocal cords will minimize the infant’s response.

Prior to the chest incision, the infant is placed in the lateral position with arms extending above the head. Careful inspection of pressure points and extremity position is required. As the result of a decrease in mediastinal pressure from the emphysematous lobe once the chest is opened, hemodynamics and ventilation usually improve. Additional opioid (10-20 mcg/kg fentanyl) and muscle relaxant can be administered at this point. Hand ventilation may be required to allow the surgeon to control vascular and airway components of the emphysematous lobe. Intermittent surveillance of hemoglobin, glucose, and arterial gas measurement will allow adjustment of ventilation, and blood and glucose administration. Nitric oxide administration may be necessary if there is evidence of the deleterious effects of pulmonary hypertension. Because of the significant impairment caused preoperatively by the emphysematous lobe, postoperative ventilation until the state of the infant’s ventilation can be adequately assessed is indicated. Postoperative pain control may be easier in a ventilated infant in the initial postoperative period.

If the surgeon contemplates a thoracoscopic approach, lung isolation needs to be planned as part of the anesthetic management unless the anesthetist and surgeon believe that insufflation of carbon dioxide will create enough exposure for the surgery. Even with a traditional thoracotomy, lung isolation may improve ventilation by excluding the emphysematous lobe and preventing further unneeded mediastinal impairment caused by an expanding, diseased lung.

In a small infant, the anesthetist isolates a lung either by main stem bronchial intubation or through the use of a Fogarty catheter. Lung isolation by bronchial intubation requires selective intubation of the nondiseased lung. To achieve selective intubation, the anesthetist after intubating the trachea in the normal way can attempt external tube manipulation based on anatomic considerations, use a fiberoptic scope, or use fluoroscopy to place the end of the tracheal tube in the correct main stem bronchus. By turning the baby’s head to the side of the lesion and turning the tracheal tube away from the lesion, advancement of the tube achieves the selective intubation desired. Accomplishing right-sided intubation is usually achievable with this technique unless there is significant anatomic distortion from the emphysematous lung.

The use of fluoroscopy can improve the success of this technique. The selective intubation can be directly observed and adjustments to the external manipulation can be guided by what is seen on the fluoroscopic screen. Once the patient is positioned in the lateral position, repeat fluoroscopy can be performed easily to confirmed position. By using an ultrathin bronchoscope that has been passed through the tracheal tube, the appropriate main stem bronchus can also be seen and entered. The tracheal tube can be passed over the bronchoscope to achieve single-lung ventilation. If the baby has a precarious respiratory status, this technique may be poorly tolerated especially since ventilation cannot occur during the process. In the small infant, the anatomy may be difficult to distinguish especially with distortion from the lung abnormality. Ideally, a cuffed tube should be used with selective main stem intubation, to prevent leakage. Occasionally in the small infant, even thin-walled cuffed tubes are too large and uncuffed tubes need to be used.

Placement of a Fogarty catheter for lung isolation requires tracheal intubation as well as intubation and placement of a 2 or 3 French catheter alongside the tracheal tube. An ultrathin bronchoscope then is placed through the tracheal tube and allows surveillance of the external catheter when advanced into the appropriate bronchus as well as balloon inflation. External rotation of the catheter and head movement may be necessary to assist in correct placement.

The conduct of the anesthetic is similar to the type employed with an open thoracotomy. A major difference is that blood products need to be immediately available since control of a vascular injury requires a change to a thoracotomy – a time period where bleeding proceeds uncontrolled. With an open thoracotomy, the surgeon can directly control bleeding usually so bleeding is often not uncontrolled. In the sick neonate, a discussion with the surgeon needs to include whether the baby will tolerate the hypercarbia seen with this approach.

Older infants are usually less symptomatic than newborns. A mask induction with volatile anesthetic is used to anesthetize the infant. Venous access can be obtained once anesthetized. Depending on the expertise of the surgeon and condition of the baby, arterial access may or not be required. Bronchoscopy can be accomplished with a low-dose propofol infusion and preexisting volatile anesthetic. Spontaneous ventilation should be preserved as much as possible prior to thoracotomy, although likely less of an issue in an older and less symptomatic child. The conduct of the anesthetic should be similar to the neonate. Babies expected to get open thoracotomy should get concomitant epidural placement for postoperative pain relief. Extubation in the operating room should be planned and anesthetic be adjusted to achieve this goal. Lung isolation is easier in older infants if thoracoscopic resection is planned.

a. Neurologic:

N/A

b. If the patient is intubated, are there any special criteria for extubation?

N/A

c. Postoperative management

N/A

What's the Evidence?

Adzick, NS. "Management of fetal lung lesions". Clin Perinatol. vol. 36. 2009. pp. 363-376.

(This article summarizes the common neonatal lung lesions seen in the fetus.)

Azizkhan, RG, Crombleholme, TM. "Congenital cystic lung disease: contemporary antenatal and postnatal management". Pediatr Surg Int. vol. 24. 2008. pp. 643-657.

(This article provides an overview of diagnostic and management strategies for congenital lobar emphysema.)

Olutoye, OO, Coleman, BG. "Prenatal diagnosis and management of congenital lobar emphysema". J Pediatr Surg. vol. 35. 2000. pp. 792-795.

(This resource covers fetal diagnosis and management strategies.)

Cote, CJ. "The anesthetic management of congenital lobar emphysema". Anesthesiology. vol. 49. 1978. pp. 296-298.

(General strategy for the anesthetic management of the infant with lobar emphysema, noting the crucial anesthetic issues.)

Schmidt, C, Rellensmann, G. "Single-lung ventilation for pulmonary lobe resection in a newborn". Anesth Analg. vol. 101. 2005. pp. 362-364.

(Discussion of one-lung ventilation as an alternative management strategy.)

Rothenberg, SS. "First decade's experience with thoracoscopic lobectomy in infants and children". J Pediatr Surg. vol. 43. 2008. pp. 40-44.

(Surgical review of thoracoscopic lobectomies in infants.)

Tsai, AY, Liechty, KW. "Outcomes after postnatal resection of prenatally diagnosed asymptomatic cystic lung lesions". J Pediatr Surg. vol. 43. 2008. pp. 513-517.

(Outcomes after postnatal resection of cystic lesions.)
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