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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
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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)
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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.