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Acute respiratory distress syndrome :wind_chime: (:leaves:Management …
Acute respiratory distress syndrome :wind_chime:
:star:
Berlin Definition
:mountain:
Causes
:star:
Direct causes
initially injure alveolar membrane
Aspiration
Pulmonary infection (bac, viral, fungal, atypical)
Inhalational injury
Pulmonary contusion
Majority of Pediatrics ARDS - pneumonia (35% - 75%)
Indirect systemic causes
first affect the endothelial component of lung
:star:
Sepsis
- M/C cause
:red_flag: has greater mortality > direct cause
Non-thoracic trauma
Transfusion related therapies
:gear:
PathoPSO
Initial insult ➯ triggers cell-mediated mech ➯ releasing a cascade of a variety of mediators ➯ disturb integrity & func of cellular linings of
Alveolar-capillary unit
Hyaline mb, flooded alveoli with
Protein-rich edema fluid :corn: & Infilitrates of PMN, Macrophages :<3: and Erythrocytes
— leading
histological hallmarks of ARDS
:<3: secrete “IL-1,6,8,10 & TNF-α” ➯ stimulate and activate PMNs
:corn: into alevolus ➯ Inactivation of surfactant ➯ Unresolved fibrin depositions and fibrin-rich hyaline membranes are formed
:skull_and_crossbones:
Predictors of Mortality
Ped. ARDS m/c dies as a result of
multi-organ failure (sepsis)
or neurological injury
~ usu apparent within 1st week of illness
Predicts by
:skull_and_crossbones:
PaO2/FiO2 ratio
and/or
Oxygenation index
:skull_and_crossbones:
Multiple organ failure
:leaves:
Management
Asterisk
for optimize clinical outcomes
*Identify ARDS trigger source
*Achieve source control
Suspected sepsis ➯
Early ATB therapy
as sepsis is common trigger for ALI
Goals
:goal_net:
:arrow_down: M&M
Hasten recovery
Optimize long term cognitive & respi func
Minimize profound Hypoxia
as ➯ led to cell death and developing brain injury
Minimize 2dary Damage to injured lung
& other organ systems
:wind_blowing_face:
Respiratory supports
:star2: = ใช้มากสุด
Non-invasive ventilation (NIV)
Success in < 1/4 of ped pt with ARDS
Preferable to intubation
:!:Often in adequate & need careful observed trial in pt with milder ARDS
:star2:2. Conventional ventilation
**M/C uses
Mode of ventilation in ped:
Pressure
limited
เนื่องจากโอกาส pneumothorax ต่ำ
ไม่ใช้ volume control — เครื่องจะตีจนกว่าvolume จะได้ ดังนั้นโอกาสเกิด pneumothorax สูงกว่า
:stars:
Pressure limited at
< 28 cmH2O
VT (tidal volume) limited at
5-8 ml/kg
ideally
PEEP
5-15 cmH2O
in an attempt to minimize atelectasis
O2 sat
88-92%
pH
7.15-7.30
acceptable (
keep permissive hypercapnia for ARDS
)
More details :pig2:
Delivered :pig2:
Tidal volume
should be
in or below
range of physiologic VT for age/body wt (5-8 mL/kg predicted body weight)
according to Lung pathology & Respiratory system compliance
Poor respiratory system compliance: VT should be 3-6 mL/kg predicted body weight
Better preserved respiratory compliance: VT should be 5-8 mL/kg ideal body weight
closer to physiologic range
(nm around 8)
:pig2:
Peak inspiratory pressure
Should be limited 28 cmH2O
Pt with :arrow_up: chest wall elastase or :arrow_down: chest wall compliance allows 29-32 cmH2O
slightly higher plateau pressure
:pig2:
PEEP
Normal PSO peep ถ่างalveoliให้ventilate
adult: 5
children: 4-5
Severe ARDS: should titrate PEEP 10-15 cmH2O to observe oxygenation & hemodynamic response
Severe PARDS (ped. Acute respiratory distress syndrome): may need PEEP > 15 cmH2O
Titrate 2 แบบ: Incremental, Decremental
:arrow_up: PEEP should closely Monitor
O2 delivery
Respiratory system compliance
Hemodynamics
Careful recruitment by
slow incremental & decremental PEEP steps
:!:
Not rec sustained inflation
:clubs:
Ventilator-induced lung injury
Overdistention
of alveoli by High transpulmonary pressures
Shear stress forces
by Repetitive alveolar recruitment and derecruitment (collapse) in pt with ARDS who receiving Mechanical ventilation
Airway pressure release ventilation (APRV)
:star2:4. High frequency oscillation ventilation (HFOV)
Hypoxic respiratory failure in pt whom
plateau airway pressures > 28 cmH2O
should considered
Exploration of potential for lung recruitment by Stepwise increase & decrease of Paw (continuous distending pressure)
under continuous monitoring of Oxygenation & CO2 response & :small_red_triangle:Hemodynamic variables
to achieve optimal lung volume (as High freq may found BP drops)
Gives relatively constant distending airway pressure with frequent small tidal variations
Should initiated
with Available CVS supports
— fluid and/or vasopressor to temporally support a decline in systemic venous return as HFOV can hv
hemodynamic effects
Settings
airway pressure (Paw) typically set
4-5 cmH2O
above mean Paw on conventional ventilation
Inspired O2 1.0
Power for adequate chest movement
Inspiratory time 33%
Flow rare 20 L/min
Frequency between 6-15 Hz
:wind_blowing_face:
Endotracheal tube
Conventionally ventilating pt with PARDS:
Cuffed
endotracheal tubes (ETTs) recommended
HFOV: allow an
ETT air leak
to augment ventilation
Normally uses
uncuffed
ETTs
:wind_blowing_face:
Gas exchange
Oxygenation & Ventilation goals titrated based on
perceived risks
of toxicity of ventilators support required
Mild
PARDS with
PEEP < 10 cmH2O
➯ keep
SpO2 92-97%
PARDS with
PEEP > 10 cmH2O
➯ keep
SpO2 88-92%
If
SpO2 < 92%
➯ monitor central venous saturation & markers of O2 delivery
Acute intracranial pathology & pulmonary HT ➯ :!:
permissive hypoxemia
Moderate to severe ARDS considers
permissive hypercapnia (pH 7.15-7.30)
to minimize ventilator-induced lung injury
Exceptions to Permissive hypercapnia
so keep normal pH
Severe pulmonary HT
Intracranial hypertension
Hemodynamic instability
Significant ventricular dysfunction
:wind_blowing_face:
Weaning method
No evidence to support specific mechanical ventilatory weaning methods for PARDS
Extubation failure m/c assoc. with Upper airway swelling
:wind_blowing_face:
Non-respiratory supportive care
Profound hypoxia or shock children ➯
maintain Hb conc
within normal range for age
Mechanically ventilated child ➯
appropriate sedation & analgesia
— standard care
:wind_blowing_face:
NO
Not routine
use
Considered in
Pt with Documented pulmonary HT
or
severe right ventricular dysfunction
Severe PARDS as a rescue form
or
Bridge to extracorporeal life support
:wind_blowing_face:
Corticosteroids
Benefits in Adult: low dose steroids within initial 2 wks of Acute lung injury
Only Clinical trial in Children
:wind_blowing_face:
Surfactant
Only children with
Direct lung injury
:wind_blowing_face:
Supporitve care
Sedation & Neuromuscular blockade
Nutrition to facilitate their recovery, maintain their growth, and meet their metabolic needs
Fluid Mx: maintain adequate intravascular volume & balance fluid
Transfusion: keep Hb > 7 mg/dL
:left_speech_bubble:
Practical points
ARDS best managed with
Low tidal volumes
Moderate PEEP
Permissive hypercapnia with Acceptable SpO2 85-94% and pH 7.2
NO & HFOV only demonstrated short-term improvements in Oxygenation
Surfactant still being studied