Lower airway disease in children and neonates
1) Typical features of neonatal and pediatric
lung disease
2) Pediatric mechanical ventilation:
Anything special to know?
3) Conventional vs high frequency ventilation
Acute respiratory failure in childhoood
pump failure
lung failure
neuromuscular diseases
primary lung disease (inflammatory)
central nervous system disease
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)
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
Intercostal Retractions
Grunting
Cyanosis
resp. freq. > 60 / Min
use of accessory muscles
glottis closure at end-expiration
intra pulmonary shunting
HMD
wet lung
meconial aspiration
congenital pneumonia
Preterm infant
LUNG IMMATURITY
Surfactant deficit
ASPHYXIE, SHOCK, ACIDOSIS
Neonate at near-term or term
Normal lung aereation,
thin septa
Generalized atelectasis,
leukocyte infiltration,
thick septa,
hyaline membranes
Medical developments in the treatment of infant RDS
Mortality
In the year 2000:
Incidence of BPD = 26% < 1500g
Lee, Canadian Network, Pediatrics 2000
O2
Mechanical
Ventilation
Antenatal steroids
CPAP
1950
1960
1970
Exogeneous
Surfactant
1980
1990
Treatment-Concept No 1: Lung-Maturation
Volume (l)
Reduced pulmonary compliance:
Normal lung
DV
C=
DP
ALI
RDS at birth
(surfactant
depleted
lung)
severe
(A)RDS
Airway pressure (cmH2O)
Concept No 2: Open the lung and keep it open
T --> Surfactant
Surfactant as a recruitment agent
post
Volume
pre
PEEP
PIP
PEEP
PIP
Pressure
Kelly E Pediatr Pulmonol 1993;15:225-30
Mortality
Bronchopulmonary dysplasia
Soll RF (Cochrane Database) 2002
MRI signal intensity from non-dependent to dependent regions
The water burden of the lung makes the lung of the preterm infant,
despite surfactant treatment,vulnerable to VILI
4-day-old, 26-week gestation infant
2-day-old, 38-week gestation infant
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
Pressure
limitation
+
High
PEEP
Acute respiratory failure in childhoood
Preterm infant
Newborn (at term)
Hyaline membrane disease
= infant RDS
Congenital pneumonia
Lung immaturity
Meconium aspiration
Congenital pneumonia
Malformations:
Lung hypoplasia, CDH
acquired lung diseases:
nosocomial pneumonia
bronchiolitis
acquired lung diseases:
nosocomial pneumonia
bronchiolitis
sepsis
sepsis
Acute respiratory failure in childhoood
Infant (1- 12 months)
Preschool age
sepsis-syndrome
sepsis-syndrome
infectious pneumonia
(RSV-bronchiolitis)
infectious pneumonia
(RSV-bronchiolitis)
non infectious pneumonia
- inhalational injury
non infectious pneumonia
- foreign body aspiration
- inhalational injury
- drowning
circulatory arrest
trauma
circulatory arrest
Common pathogens for respiratory infections:
Neonatal period:
group B beta-hemolytic streptococci (GBS)
gram negative enteric bacilli (E.coli)
Infants and
small children:
viral (especially RSV)
bacterial: Streptococcus pneumoniae
mixed infections (e.g., viral-bacterial) can
occur in 16-34% of patients
Acute viral bronchiolitis
Respiratory syncytial virus (RSV) in > 80 % of all cases
Parainfluenza I et III, Adenovirus, Rhinovirus
Transmission: surface, droplets
Variations: seasonal and biannual (?)
Primo-infection during the first year of life: 70%
At the age of 2 years: 100%.
Acute Bronchiolitis: Epidemiology
Classical resp. tract infection of the infant (up to 2 years)
Hospitalisation required in:
1-3% normal infants
10-25% infants prematurely born
Prematurity = single most important risk factor for
both hypoxemia and respiratory failure in RSV bronchiolitis
15-25% infants with cardiac malformations
15-45 % infnats with bronchopulmonary dysplasia
Prevention: Passiv Immunization
Maternal antibodies
Monoclonal antibodies: Palivizumab (Synagis) 15mg/Kg im q 1 month
Cellular
(lymphocytic)
infiltration
+ edema
Normal
bronchioli
Bronchiolitis: Physiopathology
Edema + infiltration
+ mucus +/- cellular debris
~4
increased resistance 1/R
Insp. resist. < exp. resist.
Insp. retractions
Polypnea
Exp. wheezing
Hyperinflation
The child will try to maintain
normal minute ventilation
Respiratory fatigue
Insuffisance respiratoire
Hypercapny
(= first warning sign)
·
Hypoxemia occurs later
(= vital warning sign)
PaO2 mmHg
80
50
PaCO2 mmHg
40
40
60
F resp
60 80 F resp
Typical hyperinflation in bronchiolitis
Hyperinflation and atelectasis in bronchiolitis
Acute Bronchiolitis: Treatment
Humidification
O2
Surveillance and respiratory monitoring
Bronchodilators
b-mimetics +/ipratropium bromide
inhaled adrenaline
Antiviral therapy
Ribavarin
- acute effect ?,
- longterm benefit +
Antiinflammatory tx:
Chest 2002; 122:935-9
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
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
Adult
Newborn
lung
lung
Agostini
J Appl Physiol 1959; 14: 909-913
From the newborn to the adult: FRC
chest wall
chest wall
Adult
Newborn
lung
lung
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
Newborn
EELV
above FRC
EELV
above FRC
Adult
lung
lung
Agostini
J Appl Physiol 1959; 14: 909-913
normal
lung compliance
decreased
lung compliance
How much pressure in small children?
Adults and children: Acute respiratory distress syndrome (ARDS)
Oxygenation
Lung volumes
Pulm. compliance
Mortality: 25 - 35%
Newborn: Infant respiratory distress syndrome (iRDS)
Mechanical
ventilation
Ventilator
induced lung
injury
CLD: 15 - 25%
Volume (l)
Allowable Vt and disease severity
Normal lung
ALI
(surfactant
depleted
lung)
severe
(A)RDS
Airway pressure (cmH2O)
1) Typical features of neonatal and pediatric
lung disease
2) Pediatric mechanical ventilation:
Anything special to know?
3) Conventional vs high frequency ventilation
Rationale for HFOV-based lung protective strategies
CMV
HFOV
CMV
HFOV
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.
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.
The concept of volume recruitment during HFO
Suzuki H Acta Pediatr Japan 1992; 34:494-500
Elective HFOV vs CMV in preterm infants: Outcome 28 days
All trials
Favors HFO
Favors CMV
With volume recruitment
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
Survival and CLD Morbidity
all patients
HFO (n=32)
CMV (n=39)
p - value
survivors to 30 days
HFO (n=27)
Ventilation (days)
5 (3-6)
Oxygen dependency (FiO2 > 0.21) (days)
12 (4-17)
Oxygen at 28 d, no (%)
6 (22)
CMV (n=35)
14 (6-23)
51 (20-60)
22 (63)
0.0004 *
<0.0001 *
0.002 #
survivors to 36 weeks PCA
CLD; Oxygen > 36 weeks PCA, no (%)
CMV (n=34)
12 (35)
HFO (n=27)
0 (0)
0.0006 #
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
MOAT II: Overall Survival
N
P/F
HFOV
CV
75
114 (37)
73
111 (42)
1
30d p=0.057
90d p=0.078
Proportion of Survivors
0.9
0.8
0.7
HFOV
0.6
0.5
0.4
CV
0.3
0.2
0
10
20 30 40 50 60 70 80
Days Af te r Random izat ion
90
Derdak S Am J Respir Crit Care Med 2002; 166:801–808
MOAT II: Survival - PIP  38 cmH20 (post-hoc)
1
30d p=0.019
90d p=0.026
Proportion of Survivors
0.9
0.8
0.7
HFOV
0.6
0.5
CV
0.4
0.3
0.2
0
10
20 30 40 50 60 70 80
Days Af te r Random izat ion
90
European
HFV-Meeting
2001
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.