1) Typical features of neonatal and pediatric lung disease 2) Pediatric mechanical ventilation: Anything special to know? 3)Conventional vs high frequency.

1) Typical features of neonatal and pediatric lung disease

2) Pediatric mechanical ventilation: Anything special to know?

3) Conventional vs high frequency ventilation

Lower airway disease in children and neonates

pump failure

neuromuscular diseases

central nervous system disease

lung failure

primary lung disease (inflammatory)

of various etiology

IRDS (infant) / ARDS (adult = acute)

elevated PaCO2

minimal intrapulmonary shunting

easily managed with

conventional ventilation settings

diffuse atelectasis, permeability oedema

low lung compliance, and

intrapulmonary shunting (hypoxemia)

Acute respiratory failure in childhoood

1) Typical features of neonatal and pediatric lung disease:

• Infant respiratory distress syndrome

• Acute hypoxic respiratory failure (incl. ARDS)

• Bronchiolitis (RSV-Bronchopneumonia)

Clinical characteristics of infant RDS

Polypnea resp. freq. > 60 / Min

Intercostal Retractions use of accessory muscles

Grunting glottis closure at end-expiration

Cyanosis intra pulmonary shunting

HMD wet lung

congenital pneumoniameconial aspiration

LUNG IMMATURITY

Surfactant deficit

Preterm infant

ASPHYXIE, SHOCK, ACIDOSIS

Neonate at near-term or term

Normal lung aereation, thin septa

Generalized atelectasis, leukocyte infiltration, thick septa, hyaline membranes

1950 1960 1970 1980 1990

O2MechanicalVentilation

Antenatal steroids

ExogeneousSurfactant

Mortality

Medical developments in the treatment of infant RDS

CPAP

In the year 2000:Incidence of BPD = 26% < 1500g Lee, Canadian Network, Pediatrics 2000

Treatment-Concept No 1: Lung-Maturation

Airway pressure (cmH2O)

Vo

lum

e (l

)

(surfactant depleted

lung)

Normal lung ALIRDS at birth

severe(A)RDS

Reduced pulmonary compliance: C = V P

Concept No 2: Open the lung and keep it open

T --> Surfactant

Surfactant as a recruitment agent

PEEP PIP PEEP PIP

pre post

Vo

lum

e

Pressure

Kelly E Pediatr Pulmonol 1993;15:225-30

Soll RF (Cochrane Database) 2002

Mortality

Bronchopulmonary dysplasia

4-day-old, 26-week gestation infant 2-day-old, 38-week gestation infant

MRI signal intensity from non-dependent to dependent regionsThe water burden of the lung makes the lung of the preterm infant,

despite surfactant treatment,vulnerable to VILI

Adams EW AJRCCM 2002; 166:397–402

Concept No 2: Open the lung and keep it open

T --> Surfactant

P --> positive airway pressures:- CPAP- CMV / HFO

VILI prevention: Avoidance of shear, overdistension, cyclic stress and high intrathoracic pressures

High PEEP

Pressure limitation

+

Acute respiratory failure in childhoood

Preterm infant

Hyaline membrane disease= infant RDS

Lung immaturity

Congenital pneumonia

acquired lung diseases:nosocomial pneumoniabronchiolitis

sepsis

Newborn (at term)

Congenital pneumonia

Meconium aspiration

Malformations: Lung hypoplasia, CDH

acquired lung diseases:nosocomial pneumoniabronchiolitis

sepsis

Acute respiratory failure in childhoood

Infant (1- 12 months)

sepsis-syndrome

infectious pneumonia(RSV-bronchiolitis)

non infectious pneumonia- inhalational injury

circulatory arrest

Preschool age

sepsis-syndrome

infectious pneumonia(RSV-bronchiolitis)

non infectious pneumonia- foreign body aspiration- inhalational injury- drowning

trauma

circulatory arrest

Neonatal period: group B beta-hemolytic streptococci (GBS)

gram negative enteric bacilli (E.coli)

Infants and viral (especially RSV) small children:

bacterial: Streptococcus pneumoniae

mixed infections (e.g., viral-bacterial) can occur in 16-34% of patients

Common pathogens for respiratory infections:

Acute viral bronchiolitis

Primo-infection during the first year of life: 70%At the age of 2 years: 100%.

Transmission: surface, droplets

Variations: seasonal and biannual (?)

Respiratory syncytial virus (RSV) in > 80 % of all casesParainfluenza I et III, Adenovirus, Rhinovirus

Acute Bronchiolitis: Epidemiology

Classical resp. tract infection of the infant (up to 2 years)

Hospitalisation required in:1-3% normal infants10-25% infants prematurely born

Prematurity = single most important risk factor for both hypoxemia and respiratory failure in RSV bronchiolitis

15-25% infants with cardiac malformations15-45 % infnats with bronchopulmonary dysplasia

Prevention: Passiv ImmunizationMaternal antibodiesMonoclonal antibodies: Palivizumab (Synagis) 15mg/Kg im q 1 month

Cellular (lymphocytic) infiltration + edema

Normal bronchioli

Bronchiolitis: Physiopathology

Edema + infiltration increased resistance + mucus +/- cellular debris

~ 1/R

4

Insp. resist. < exp. resist.

Insp. retractions PolypneaExp. wheezingHyperinflation

Respiratory fatigue Insuffisance respiratoire

The child will try to maintain normal minute ventilation

Hypercapny (= first warning sign)

Hypoxemia occurs later (= vital warning sign)

·

PaO2 mmHg PaCO2 mmHg

80 4050

40 60 F resp 60 80 F resp

Typical hyperinflation in bronchiolitis

Hyperinflation and atelectasis in bronchiolitis

HumidificationO2

Surveillance and respiratory monitoring

Bronchodilators -mimetics +/-ipratropium bromideinhaled adrenaline

Antiviral therapy Ribavarin- acute effect ?, - longterm benefit + Chest 2002; 122:935-9

Antiinflammatory tx: Steroides- acute phase: shortens length of hospital stay but not duration of ICU-stay or mechanical ventilation Thorax 1997; 52:634-7

- not effective on long term outcome Pediatr Pulmonol 2000; 30:92-96

CPAP, non-invasive ventilation, intubation + ev. HFO

Acute Bronchiolitis: Treatment

1) Typical features of neonatal and pediatric lung disease

2) Pediatric mechanical ventilation: Anything special to know?

3) Conventional vs high frequency ventilation

From the newborn to the adult: Physiology

Chest wall compliance

FRC

Elastic Recoil

Rib cage distortion

Pleural pressure distortion

From the newborn to the adult: Crs

chest wall chest wall

lunglung

Newborn Adult

Agostini J Appl Physiol 1959; 14: 909-913

From the newborn to the adult: FRC

chest wall chest wall

lunglung

Newborn Adult

Agostini J Appl Physiol 1959; 14: 909-913

To maintain a reasonable EELV the neonate closes his glottis at the end of expiration (to avoid lung unit closure)

Therefore:

An intubated neonate or infant is always ventilated with PEEP

From the newborn to the adult: Paw effect

chest wall chest wall

lunglung

Newborn Adult

Agostini J Appl Physiol 1959; 14: 909-913

EELV above FRC

EELV above FRC

decreased lung compliance

normal lung compliance

How much pressure in small children?

Adults and children: Acute respiratory distress syndrome (ARDS)

Newborn: Infant respiratory distress syndrome (iRDS)

Mortality: 25 - 35%

CLD: 15 - 25%

Ventilator induced lung

injury

Mechanical ventilation

Oxygenation

Lung volumes

Pulm. compliance

Airway pressure (cmH2O)

Vo

lum

e (l

)(surfactant depleted

lung)

Normal lung ALI

severe(A)RDS

Allowable Vt and disease severity

1) Typical features of neonatal and pediatric lung disease

2) Pediatric mechanical ventilation: Anything special to know?

3) Conventional vs high frequency ventilation

1. HFOV uses very small VTs. This allows the use of higher EELVs to achieve greater levels of lung recruitment while avoiding injury from excessive EILV.

CMVHFOV

CMVHFOV

Rationale for HFOV-based lung protective strategies

2. Respiratory rates with HFOV are much higher than with CV. This allows the maintenance of normal or near-normal PaCO2 levels, even with very small Vts.

Suzuki H Acta Pediatr Japan 1992; 34:494-500

The concept of volume recruitment during HFO

Favors HFO Favors CMV

Elective HFOV vs CMV in preterm infants: Outcome 28 days

With volume recruitment

All trials

0.0006 #

Survival and CLD Morbidity

all patients HFO (n=32) CMV (n=39) p - value

survivors to 30 days HFO (n=27) CMV (n=35)

Ventilation (days) 5 (3-6) 14 (6-23) 0.0004 *

Oxygen dependency (FiO2 > 0.21) (days) 12 (4-17) 51 (20-60) <0.0001 *

Oxygen at 28 d, no (%) 6 (22) 22 (63) 0.002 #

survivors to 36 weeks PCA HFO (n=27) CMV (n=34)

CLD; Oxygen > 36 weeks PCA, no (%) 0 (0) 12 (35)

Values are given as the median (95% CI) or the number (percentage) of patients; * Mantel-Cox log-rank; # Fisher's exact

Rimensberger PC et al. Pediatrics 2000; 105:1202-1208

First Intention HFO with early lung volume recruitment

Retrospective study with historical cohort in preterm infants with RDS,mean GA = 27.7 (± 1.9), < 32 w / mean BW = 970 (± 250), < 1200 g

MOAT II: Overall Survival

CV

HFOV

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 10 20 30 40 50 60 70 80 90

Pro

po

rti

on

of

Su

rv

ivo

rs

Days After Randomization

HFOV CVN 75 73 P/F 114 (37) 111 (42)

Derdak S Am J Respir Crit Care Med 2002; 166:801–808

30d p=0.05790d p=0.078

MOAT II: Survival - PIP 38 cmH20 (post-hoc)

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 10 20 30 40 50 60 70 80 90

Pro

po

rti

on

of

Su

rv

ivo

rs

Days After Randomization

CV

30d p=0.01990d p=0.026

HFOV

EuropeanHFV-Meeting2001

Conclusions

Although there exist some special respiratory pathologies in early childhood, treatment concepts are not to much different from the one in adult patients.

However, it is important to recognize early signs of respiratory distress in infants and small children, because this patients are at high risk for a sudden cardiac arrest.