General term for the pulmonary sequelae of premature birth. In fact, the definition of bronchodysplasia consists in the description of risk factors for its development. This definition has evolved according to the progressive improvement of the survival of premature babies following the improvement of artificial ventilation, prenatal administration of corticoids and surfactant.

Today, a distinction is made between:

-        old bronchodysplasia: for children born after 32 weeks of gestational age: oxygen dependency at 28 days of life. This is essentially a consequence of artificial ventilation

-        new bronchodysplasia: for children born before 32 weeks of gestational age: oxygen dependency at 36 weeks of postconceptional age, the severity of which is classified as:

- grade 1: nasal O2 < 2 L/min

- grade 2: nasal O2 > 2 L/min or CPAP or non-invasive ventilation

- grade 3: invasive ventilation

Physiopathology:

1) old bronchodysplasia

-        occurs in premature babies born > 32 weeks of gestation

-        is essentially the result of postnatal ventilation: aggressive ventilation, oxidative stress, infection, nutritional deficiency, fluid overload of the lung

-        structural consequences: areas of atelectasis and emphysema, interstitial fibroproliferation, hyperplasia of bronchial smooth muscles, hyperreactivity to other aggressions (infection, inflammation)

-        the presence of a congenital cardiopathy with a left-right shunt worsens the evolution of the pathology

-        leads to a clinical picture similar to chronic obstructive pulmonary disease but at an early age. In case of chronic hypoxemia, or left-right shunt, pulmonary hypertension may appear.

2) new bronchodysplasia

-        occurs in premature babies born < 32 weeks of gestation

-        is a complex and multifactorial disease due to several factors

a)        prenatal: pre-eclampsia, maternal smoking, placental pathology, intrauterine growth retardation, chorioamnionitis, genetic factors

b)        perinatal: premature birth

c)        post-natal: arrest of the pulmonary development, surfactant deficiency, corticosteroids, artificial ventilation, episodes of hyperoxia and oxidative stress, inflammation (infection, enterocolitis), AND cardiovascular factors: remodeling of the pulmonary vascular tree, shunts (ductus arteriosus, foramen ovale), pulmonary arterial hypertension, stenosis of the pulmonary veins

-        structural consequences; variable association of lesions in :

a)        large airways: stenosis and/or malacia (trachea, bronchi) (36 %)

b)        small airways: bronchial hyperreactivity which only partially responds to β2 agonists

c)        of the pulmonary parenchyma: alveolar simplification (fewer and larger alveoli) leading to decreased gas exchange surface and a  risk of chronic hypoxemia; the pulmonary function is diminished and progressively evolves towards an early chronic obstructive pulmonary disease (adolescence)

d)        pulmonary vascularization: anomalies in the development of pulmonary vessels by dysangiogenesis (decrease in vascular arborization and pulmonary capillaries), remodeling of the walls of the pulmonary arteries (hyperplasia of smooth muscle cells), endothelial dysfunction (less production of NO and prostacyclins): this combination of anatomical and functional factors leads to the development of pulmonary hypertension (15-25 % of cases) of variable severity aggravated by the persistence of fetal shunts (ductus arteriosus, foramen ovale). This pulmonary hypertension worsens with time

e)        systemic vascularization: presence of left ventricular diastolic dysfunction secondary to systemic hypertension (48 % of cases); it may lead to post-capillary pulmonary hypertension. Progressive stenosis of one or more pulmonary veins (23 %) may also occur (secondary to turbulent blood flow due to pulmonary hypertension)

-        variable evolution: some premature babies evolve towards a cure without major sequelae (no hypoxemia, but risk of bronchial hyperreactivity and, in the long term, pulmonary hypertension) but others present a progressive and severe pulmonary disease

Treatments: diuretics, bronchodilators, sildenafil in case of pulmonary hypertension or converting enzyme inhibitors (captopril) in case of left ventricular dysfunction, sometimes corticosteroids and O2 supplementation:

Anesthetic implications:

-        depending on gestational age at birth: old form (COPD) or new form (mainly vascular disease) ?

-        echocardiography: associated malformation ? ASD, VSD, pulmonary stenosis, ductus arteriosus ?

-        if old bronchodysplasia:

♦        treat as bronchial hyperreactivity: usual bronchodilator before induction,

- if new bronchodysplasia: grade ?

♦        ENT advice: tracheobronchomalacia ?

♦        recent complete echocardiac to look for:

1)        pulmonary hypertension: flattening of the septum or even bulging towards the LV, dilatation and or hypertrophy of the RV ? Look out ! Tricuspid valve regurgitation is not always present and bad function of the RV results in  underestimation of the pulmonary arterial pressure; pulmonary arterial pressure estimated normal, infra- (< 50 %) normo- (50-75 %) or suprasystemic (> 75 %) ? A cardiac catheterization is sometimes necessary;

2)        right ventricular function: hypertrophy ? systolic or diastolic dysfunction ?

3)        left ventricular function: diastolic dysfunction ? contractility ?

4)        presence of a patent foramen ovale ? If yes, it can act as a decompression valve of the RA and the RV in case of pulmonary hypertension crisis: desaturation but survival

5)        presence of pulmonary vein stenosis ? In these cases, it may be preferable to perform a dilatation by percutaneous catheterization before the planned surgery

♦        plan a stay in the intensive care unit for the post-operative period: risk of respiratory decompensation and pulmonary hypertension crisis

♦        treat as bronchial hyperreactivity: usual bronchodilator before induction

♦        induction: ketamine or etomidate rather than propofol

♦        intubation under deep anesthesia and curarization: avoid cough, bucking, laryngospasm, bronchospasm

♦        avoid systemic hypotension: risk of right ventricular ischemia and acute decompensation if the foramen ovale is not patent

♦        ventilation: ideal: volume-guaranteed pressure-controlled ventilation, otherwise controlled pressure; I/E ratio 1/1.5 except if bronchospasm, rather slow respiratory rate (20- 22/min), moderate PEEP

♦        extubation can be problematic: avoid coughing, bucking, laryngospasm, bronchospasm

References:

-        Thebaud B, Goss KN, Laughon M, Whitsett JA et al.
Disease Primers. Bronchopulmonary dysplasia.
Nature Review 2019;5:78

-        Krishnan U, Feinstein JA, Adatia I, Austin ED, Mullen MP, Hopper RK et al.
Evaluation and management of pulmonary hypertension in children with bronchopulmonary dysplasia.
J Pediatr 2017; 188:24-34, e1

-        Steurer MA, Nawaytou H, Guslits E, Colglazier E et al.
Mortality in infgants with bronchopulomnary dysplasia: data from cardiac catheterization.
Pediatr Pulmonol 2019; 54:804-13

-        Sehgal A, Steenhorst JJ, Mclennan DI, Merkus D, Ivy D, McNamara P.
The left heart, systemic circulation, and bronchopulmonary dysplasia: relevance to pathophysiology and therapeutics.
J Pediatr 2020; 225:13-33, e2

-        Schmidt AR, Ramamoorthy C.
Bronchopulmonary dysplasia.
Pediatr Anesth 2022; 32:174-80

-        Sabourdin N.
Mise au point sur la bronchodysplasie de l’ancien prématuré.
Anesth Réanim 2022; 8:576-81.

Updated: April 2023