Guideline on The Management Of Acute Respiratory Distress Syndrome (ARDS) in Adult ICU

Aim and Scope
1)To ensure that all patients in ICU with ARDS are correctly identified and receive   the best evidence based treatment.
Definition
Onset of ARDS (diagnosis) must be acute, within 7 days of some defined event,  which may be sepsis, pneumonia, or simply a patient’s recognition of worsening  respiratory symptoms. (Most cases of ARDS occur within 72 hours of recognition of  the presumed trigger.)
Bilateral opacities consistent with pulmonary edema must be present but may be
detected on CT or chest X-ray. Ultrasound may also be used to define lung  pathology and the presence of non cardiogenic extra vascular lung water
Respiratory failure can be “not fully explained by cardiac failure or fluid overload,”
in the physician’s best estimation using available information.
ARDS Severity  PaO2/FiO2*  Mortality
()kpa
Mild 200 – 300 27%
(27 – 40)
Moderate 100 – 200 32%
(13-27)
Severe < 100 45%
(<13)
*on PEEP 5+ 
General Measures
1 All patients should have 100% compliance with the Ventilator Care  bundle
2 No chest physiotherapy unless as a trial to improve lobar collapse
3 Minimal suctioning via ETT
4 Normal feed as per protocol
5 Fluids. All patients will have a liberal fluid strategy during the initial resuscitation  phase (usually 0-48hours). If patients are then still vasopressor dependent, we will  aim to maintain a neutral fluid balance. Once inotropes are discontinued or are  being used in low doses to compensate for sedation, then we will aim to remove  the excess fluid that has been given. This will initially be performed using diuretics  but may require CVVHF if the fluid balance remains positive. Vasopressor may be  required to support the BP and  allow diuresis
6.     Ventilation
Mode: 1)VC SIMV  ( Volume control, synchronized mandatory ventilation)
           2) Volume assured PC SIMV (Pressure control, volume assured,  synchronized mandatory ventilation) This is not available on all ventilators
Settings: Peep 5-10cmH2O
               TV 6ml/kg ideal body weight.
               Plateau pressure < 30cmH20
               Rate: titrated to control PaCO2
Ideal body weight is calculated as follows:
Males        Length (in cm) – 100
Females   Length (in cm) – 105
The tidal volume required must be written every day at the top on the ICU  observation chart in red. It is the responsibility of the ICU consultant 1 to ensure that  this is done
7   All patients will have subglottic suction
The following patient group will be managed with an
extended ARDS care bundle
Diagnosis of ARDS as per above criteria
Ventilated for <36hours
A PaO2/FiO2 ratio<20kpa(150mmHg) for 12-24 hours on an FiO2 >0.6. 
NDMR
All patients who meet the above criteria  will be given a cisatracurium infusion. This  will be titrated to a train of four (TOF of 2 twitches). Paralyses will continue for as  long as they meet prone ventilation criteria.
Prone ventilation
All patients who do not have specific contraindications to prone ventilation will be  prone ventilated. They will be placed prone as per unit guidelines. They will remain  prone ventilated for at least 16 hours.

Prone ventilation will be stopped when any of the following criteria are met:
1) Improvement in oxygenation. This is defined as a Pao2:Fio2 ratio of ≥20, with a  PEEP of ≤10 cm of water and an Fio2 of ≤0.6. These criteria have to be sustained in  the supine position at least 4 hours after the end of the last prone session
2) A patient deteriorates compared to their PaO2:FiO2 ratio when supine
3) > 96 hours since first episode of prone ventilation
Management of a raised PaCO2
1) pH> 7.2 secondary to a respiratory acidosis will be tolerated
     The respiratory rate and not the tidal volume should be adjusted to help maintain  a    pH >7.2
2) If the pH remains less than 7.2  for >24 hours then consideration should be given  to using extra corporeal CO2 clearance
3) If the pH is < 7.1 for 4 hours or more with no other therapy (nebulisers etc)  available to reduce it, then extra corporeal CO2 clearance should be considered.
4) All patients being considered for extra corporeal CO2 clearance should initially  be discussed with our regional ECMO centre.
Management of a persistently low PaO2 (<8kpa)
1) Increase FiO2
2) Add nebulised prostacycline as per guideline
3) Maintain TV and peep
4) Discuss with regional ECMO centre
Recruitment maneuvers
1) All patients will have ‘inspiratory hold’ recruitment. This will be performed by  using the inspiratory hold function on the ventilators.
2) This will be 30cm H2O for 30 seconds
3) It should be performed after each disconnection or suctioning episode
4) It should be repeated as required when clinically it is felt that recruitment is  required.
5) It may be used as a trial to improve the PaO2

Steroids
All patients will be given methylprednisolone 0,5mg/kg/day (or equivalent) for 14  days unless contraindicated for standard reasons.
Documentation Control
Development of Policy: Consultation with: Approved by: Signature:
Print name and position: Date of Approval: Review Date:
References
            Dr James Low
Dr. Craig Morris, Dr. Nick Reynolds
ICU  Clinical Group
Nov 2013
Nov 2016
1) JAMA, June 2012 – Vol 307, No. 23
2) NEJM  June 2013 – Vol 368, No 23
3) NEJM  August 2001- Vol 345, No. 8
4) Crit Care Med. 2009 37(9):2680.