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The Full Story on CPAMs

Here we cover Congenital Pulmonary Airway Malformations (CPAMs) through a story with the help of Dr. Todd Ponsky, Dr. Pam Choi, Dr. Beth Rymeski, Dr. Jacob Langer, and Dr. Steven Rothenberg.

Hosts: Ellen Encisco & Rod Gerardo

Chapter 1: Prenatal (00:00)

  1. Lung mass seen on a prenatal ultrasound (01:23)

    1. Differential diagnosis (01:50)

      1. Congenital Pulmonary Airway Malformation (CPAM)

      2. Bronchopulmonary Sequestration (BPS)

      3. Hybrid CPAM/BPS

      4. Congenital Lobar Emphysema (CLE)

      5. Bronchogenic Cyst (BC)

      6. Congenital Diaphragmatic Hernia (CDH)

    2. Ultrasound characteristics of lung lesions on differential (02:55)

      1. CPAM: hyperechoic, heterogeneous tissue with multiple hypoechoic cysts, which can be large or small 

      2. BPS: hyperechoic, relatively homogeneous mass. Evaluate vascular supply with Doppler 

      3. CLE: fluid-overloaded, expanded lung tissue with homogeneous hyperechogenicity 

      4. BC: anechoic, uni- or bilocular well-defined masses in middle mediastinum or perihilar regions. May see hyperechoic fluid representing retained fetal lung fluid from secondary bronchial compression 

      5. CDH: echogenic lung mass, cystic or solid 

  2. CPAMs general information (03:47)

    1. Groups of benign cystic pulmonary lesions with large or small cysts. Abnormally developed lung that arises from normal bronchial airways but doesn’t have normal alveoli so can’t participate in gas exchanged

    2. Epidemiology

      1. Incidence: 1 : 8,000-35,000 births

      2. 60% of prenatally-diagnosed lung lesions

    3. Embryology (04:23)

      1. Lung development stages:

        1. Embryonic stage (3-6 weeks)

        2. Pseudoglandular stage (5-17 weeks)

        3. Canalicular stage (16-25 weeks)

        4. Saccular stage (24 weeks – birth)

        5. Alveolar stage (36 weeks – 8 years)

      2. CPAMs: overgrowth of bronchioles with incomplete development of alveoli, thought to be related to transient bronchial obstruction

    4. Stocker classification (05:08)

      1. Type 0: tracheobronchial (rare)

      2. Type 1: distal bronchi/proximal bronchiole (most common, 60-70%)

      3. Type 2: bronchiolar (second most common)

      4. Type 3: distal bronchioles/alveoli

      5. Type 4: distal acini (rare)

    5. Natural history (06:45)

      1. Grow around weeks 20-25, plateau around week 28

  3. Prenatal assessment of CPAMs

    1. Imaging characteristics to look for (07:24)

      1. Size of lesion

      2. Mediastinal shift?

      3. Polyhydramnios?

      4. Hydrops?

        1. Hydrops = abnormal buildup of fluid in two or more body compartments (e.g. ascites, pleural effusion, pericardial effusion). Can happen with CPAMs because lung lesion can compress the heart, impair venous return, and lead to heart failure and subsequent fluid buildup elsewhere.

      5. Microcystic vs macrocystic

        1. Microcystic < 5 mm

        2. Macrocystic ≥ 5 mm

      6. CVR (CPAM Volume Ratio)

        1. = (CPAM Volume x 0.52) / head circumference

        2. CVR > 1.6 is associated with increased risk of hydrops (75%) and subsequent poor outcome

    2. Prenatal monitoring (09:50)

      1. Serial ultrasounds

        1. If CVR < 1.6, monitor weekly

        2. If CVR > 1.6 or other concerning findings, monitor twice weekly

      2. Consider fetal MRI

      3. Consider fetal echocardiogram if evidence of hydrops on ultrasound/MRI. Abnormal findings:

        1. Increased or decreased cardiac output

        2. Ventricular hypertrophy

        3. Atrial or ventricular chamber dilation

        4. Cardiomegaly

        5. Valvular regurgitation

        6. Diastolic dysfunction

  4. Management of CPAMs based on prenatal imaging findings (source: Morris et al, JPS, 2009) (12:48)

    1. CVR < 1.6

      1. Delivery plan 

        1. Can be normal vaginal delivery; C section not necessarily indicated

    2. High-risk (CVR > 1.6 or fetal hydrops)

      1. If ≥ 28 (or 32) weeks

        1. Delivery plan (should be at fetal care center)

          1. If no mediastinal shift – standard delivery

          2. If mediastinal shift – consider EXIT-to-resection

            1. Partially deliver fetus and perform a thoracotomy for lung lesion resection while still connected to umbilical cord

            2. Needs to be done quickly, before placenta starts to separate from uterine wall

      2. If < 28 (or 32) weeks

        1. First try maternal steroids: 12 mg betamethasone x 2 doses, 24 hours apart

        2. If no improvement with steroids:

          1. Macrocystic (≥ 5 mm) – thoraco-amniotic shunt

            1. Usually done by MFM under ultrasound guidance

            2. Aim for posterior rib spaces so hopefully the fetus doesn’t grab and dislodge

          2. Microcystic (< 5 mm) or macrocystic with no improvement after thoracoamniotic shunt – consider open fetal surgery

            1. Partially deliver fetus, remove lung lesion via thoracotomy, then put fetus back in uterus

            2. High-risk

    3. If the mother develops Mirror syndrome (mother is showing evidence of the fetus’s situation, such as peripheral edema, pulmonary effusion, etc.)

      1. Deliver (no matter the gestational age)


Chapter 2: Postnatal (21:46)

  1. Postnatal assessment (22:05)

    1. Asymptomatic (majority of cases) vs symptomatic (respiratory distress)

      1. Air trapping: air enters area of CPAM but can’t come out as easily, so progressiver hyperventilation occurs and can lead to respiratory distress

      2. If symptomatic, proceed to surgical resection

    2. Postnatal imaging 

      1. Chest x-ray

        1. Assess laterality of lesion if patient is symptomatic and you are proceeding to surgery

        2. Normal radiograph does not rule out a pulmonary lesion 

      2. Multidetector CT angiogram (gold standard) – Can be done 1-3 months after term delivery if the infant remains asymptomatic. Imaging findings to assess: 

        1. Inspiratory and expiratory phases

        2. Location and extent of lesion 

        3. Airway/bronchial tree 

        4. Lesion characteristics 

          1. Cystic? Solid? Hybrid? 

          2. Largest and average cyst size – determine type of CPAM 

        5. Vascularization – feeding vessel?

        6. Surrounding tissues 

          1. Mediastinal shift 

          2. Atelectasis 

          3. Perilesional low-attenuation areas 

          4. Air-trapping and emphysema 

  2. Surgical decision-making (24:35)

    1. Indications for surgery 

      1. Symptomatic after birth 

      2. Asymptomatic CPAM – discussion with family

        1. Arguments for resection of asymptomatic lung malformation

          1. Malignancy (pre-existing or later transformation)

            1. Pleuropulmonary blastoma (PPB)

            2. Associated with DICER1 mutation

            3. 2021 MWPSC study

          2. Risk of infection 

          3. Possible compensatory lung growth

        2. Disadvantages of resection 

          1. Operative mortality 

          2. Operative morbidity 

          3. Development of malignancy despite resection 

    2. Alternatives to surgery 

      1. Observation 

        1. Possible routine imaging with CXR or CT but CXR may not show much and frequent CTs have the risk of malignancy development


Chapter 3: Surgery details (33:24)

  1. Possible operative approaches for lobectomy

    1. Thoracotomy (open resection)

    2. Thoracoscopy

  2. Risks of surgery (33:36)

    1. Bleeding requiring transfusion (3.7-11%)

    2. Prolonged post-op mechanical ventilation (8%)

    3. Surgical site infection (1.2%)

    4. Prolonged air leak (1.2-4%)

    5. Bronchial plug

    6. Temporary or permanent nerve injury (4%)

    7. Recurrent or persistent cystic lesions on radiographs (1.2-15%)

    8. Mortality

  3. Contraindications to surgery (34:38)

    1. Presence of other severe comorbidities that would significantly increase the risk of surgery 

    2. Active pneumonia or pulmonary abscess (wait 6-8 weeks after resolution)

    3. Multifocal CPAM where multiple resections would significantly decrease pulmonary function 

  4. Timing of surgery (35:30)

    1. Dependent on surgeon preference, usually within 6 months of birth

  5. Preoperative preparation (36:15)

    1. Labs: CBC, type & cross

    2. Review CT scan

    3. Have blood available

    4. Review with anesthesiology

      1. Single-lung ventilation preferable

        1. Main stem intubation usually

      2. If single-lung ventilation is not tolerated, CO2 insufflation can help collapse the lung

        1. Pitfalls: overventilation, high peak ventilator pressures

      3. Initial oxygen desaturation and hypercarbia will resolve

    5. Patient positioning (37:38)

      1. Lateral decubitus position 

      2. Dr. Rothenberg moves the patient to the edge of the table, surgeon and assistant face anterior chest

      3. Use towel rolls or beanbag to help with positioning

  6. Doing the operation. Note: details below describe a left lower lobectomy 

    1. Trocar placement (38:37)

      1. Depends on which lobe is being resected

      2. Scope port should be positioned over where you think the major fissure is, in the mid-axillary line, anterior to the tip of the scapula

        1. Usually 5th-6th interspace for lower lobectomy

      3. Working ports in anterior axillary line

        1. Left hand under camera port (5th-6th interspace)

        2. Right hand port just above diaphragm (8th or 9th interspace)

    2. Operative steps (40:20)

      1. ** Note about vascular control: dissect out each vessel, seal proximal and distal, then cut partway in between. If you see bleeding, then get control. Complete cut if no bleeding.

      2. Take down inferior pulmonary ligament to the level of the inferior pulmonary vein. If there is a feeding vessel, it would be in here.

      3. Assess major fissure – is it complete? 

      4. If complete, you’ll see pulmonary artery

      5. If fissure is incomplete, then slowly and methodically complete it front to back. Work posteriorly and down fissure with vessel sealer.

      6. Once pulmonary artery trunk is reached, will see four branches in lower lobe

        1. Superior segmental branch is a little higher and more posterior. Dissect and divide.

        2. Then access basal segments

      7. Bronchus is posterior to artery and can be used to guide dissection

      8. If adequate length, divide basal artery trunk. Otherwise, dissect and divide basal segment branches individually.

        1. If stapler is used, make sure to have enough proximal vessel exposed to apply a clamp and make sure you have vascular control.

      9. Dissect and divide bronchus similarly – superior segmental bronchus first. 

        1. Use clips or 5 mm stapler.

        2. If 10-15 kg child, can use 12 mm stapler

      10. Pulmonary vein is just posterior to bronchus, so you’ll see it after you divide the bronchus.

        1. Identify bifurcation. Dissect and divide inferior branch first.

        2. Divide trunk with stapler. Make sure to have control of proximal trunk with atraumatic grasper.

        3. Could also divide individual segmental branches separately.

        4. ** Make sure not to divide trunk near pericardium as if the device fails, the vessel will retract into the pericardium and massive hemorrhage will ensue.

    3. Other tips and tricks

      1. If large cysts are in your way, use vessel sealer to decompress

      2. Try to work anterior to posterior in the same plane, try not to flip back and forth

      3. Don’t be afraid to convert to open if you’re having a hard time

      4. Podcast with Dr. Rothenberg on Neonatal Lung Lesions + see videos of thoracoscopic lobectomies in the app!


Chapter 4: Post-operative care (51:00)

  1. Inpatient observation

    1. Chest tube remains until low output and no air leak

    2. Post-op pain management: consider regional blocks if thoracotomy performed. Oral opioids, NSAIDs, acetaminophen typically used

    3. Average length of stay 2-3 days

  2. Outpatient follow-up

    1. 3-4 weeks after surgery with chest x-ray

    2. Then at regular intervals per surgeon discretion

  3. Follow-up pathology report to check for malignancy


References 

  • Kunisaki, Shaun M, et al. “Congenital Pulmonary Airway Malformations.” Pediatric Surgery NaT, American Pediatric Surgical Association, 2021. APSA Webapp, www.pedsurglibrary.com/apsa/view/Pediatric-Surgery-NaT/829070/all/Congenital_Pulmonary_Airway_Malfor…. 

  • Alamo, Leonor, et al. “Prenatal diagnosis of congenital lung malformations.” Pediatric radiology 42.3 (2012): 273-283. 

  • Kunisaki, Shaun M., et al. “Vanishing fetal lung malformations: prenatal sonographic characteristics and postnatal outcomes.” Journal of pediatric surgery 50.6 (2015): 978-982. 

  • Downard, Cynthia D., et al. “Treatment of congenital pulmonary airway malformations: a systematic review from the APSA outcomes and evidence based practice committee.” Pediatric surgery international 33.9 (2017): 939-953. 

  • Hermelijn, Sergei M., et al. “A clinical guideline for structured assessment of CT-imaging in congenital lung abnormalities.” Paediatric respiratory reviews 37 (2021): 80-88. 

  • Baird, Robert, Pramod S. Puligandla, and Jean-Martin Laberge. “Congenital lung malformations: informing best practice.” Seminars in pediatric surgery. Vol. 23. No. 5. WB Saunders, 2014. 

  • Loh, Kenneth C., et al. “Microcystic congenital pulmonary airway malformation with hydrops fetalis: steroids vs open fetal resection.” Journal of pediatric surgery 47.1 (2012): 36-39. 

  • Stocker, J. Thomas. “Cystic lung disease in infants and children.” Fetal and pediatric pathology 28.4 (2009): 155-184. 

  • Davenport, Mark, and Ernst Eber. “Long term respiratory outcomes of congenital thoracic malformations.” Seminars in Fetal and Neonatal Medicine. Vol. 17. No. 2. WB Saunders, 2012. 

  • Miniati, Douglas N., et al. “Prenatal presentation and outcome of children with pleuropulmonary blastoma.” Journal of pediatric surgery 41.1 (2006): 66-71. 

  • Hall, Nigel J., and Michael P. Stanton. “Long-term outcomes of congenital lung malformations.” Seminars in pediatric surgery. Vol. 26. No. 5. WB Saunders, 2017. 

  • Morris, Lee M., et al. “High-risk fetal congenital pulmonary airway malformations have a variable response to steroids.” Journal of pediatric surgery 44.1 (2009): 60-65.

  • Kunisaki, Shaun M., et al. “Pleuropulmonary Blastoma in Pediatric Lung Lesions.” Pediatrics 147.4 (2021).

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