Resp-failure neo-ped

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Transcript Resp-failure neo-ped

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 neuromuscular diseases central nervous system disease

elevated PaCO2 minimal intrapulmonary shunting easily managed with conventional ventilation settings

lung failure primary lung disease (inflammatory) of various etiology IRDS (infant) / ARDS (adult = acute)

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 O 2 Mechanical Ventilation In the year 2000: Incidence of BPD = 26% < 1500g

Lee, Canadian Network, Pediatrics 2000

Antenatal steroids CPAP Exogeneous Surfactant

1950 1960 1970 1980 1990

Treatment-Concept No 1: Lung-Maturation

Reduced pulmonary compliance: C =

D D

V P Normal lung ALI RDS at birth

(surfactant depleted lung)

severe (A)RDS Airway pressure (cmH 2 O)

Concept No 2: Open the lung and keep it open T --> Surfactant

Surfactant as a recruitment agent

pre post 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 Hyaline membrane disease = infant RDS Lung immaturity Congenital pneumonia acquired lung diseases: nosocomial pneumonia bronchiolitis sepsis Newborn (at term) Congenital pneumonia Meconium aspiration Malformations: Lung hypoplasia, CDH acquired lung diseases: nosocomial pneumonia bronchiolitis 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

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 ~ increased resistance 4 Insp. resist. < exp. resist.

Insp. retractions Polypnea Exp. wheezing · Hyperinflation Respiratory fatigue Insuffisance respiratoire The child will try to maintain normal minute ventilation Hypercapny (= first warning sign) 80 50 PaO2 mmHg 40 PaCO2 mmHg F resp Hypoxemia occurs later (= vital warning sign) 60 80 F resp

Typical hyperinflation in bronchiolitis

Hyperinflation and atelectasis in bronchiolitis

Acute Bronchiolitis: Treatment

Humidification O 2 Surveillance and respiratory monitoring Bronchodilators

b

-mimetics +/ ipratropium bromide inhaled adrenaline Antiviral therapy Antiinflammatory tx: Ribavarin - acute effect ?, - longterm benefit +

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

Newborn Adult

lung lung Agostini J Appl Physiol 1959; 14: 909-913

From the newborn to the adult: FRC

chest wall chest wall

Newborn Adult

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 lung

Newborn EELV above FRC

chest wall

EELV above FRC Adult

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%

Allowable V t and disease severity Normal lung ALI

(surfactant depleted lung)

severe (A)RDS Airway pressure (cmH 2 O)

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 survivors to 36 weeks PCA

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

HFO (n=32) survivors to 30 days

Ventilation (days) Oxygen dependency (FiO2 > 0.21) (days) Oxygen at 28 d, no (%)

HFO (n=27)

5 (3-6) 12 (4-17) 6 (22)

HFO (n=27)

0 (0)

CMV (n=39) CMV (n=35)

14 (6-23) 51 (20-60) 22 (63)

CMV (n=34)

12 (35) p - value 0.0004 * <0.0001 * 0.002 # 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 75 114 (37) CV 73 111 (42)

1 0.9

0.8

30d p=0.057

90d p=0.078

0.7

0.6

0.5

0.4

HFOV CV

0.3

0.2

0 10 20 30 40 50 60 70

Days After Randomiz ation

80 90 Derdak S Am J Respir Crit Care Med 2002; 166:801 –808

MOAT II: Survival - PIP

38 cmH20 (post-hoc)

1 0.9

30d p=0.019

90d p=0.026

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0

HFOV CV

10 20 30 40 50 60 70

Days After Randomiz ation

80 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.