Management of Acute Respiratory Distress Syndrome (ARDS)

In this article, we will discuss the Management of Acute Respiratory Distress Syndrome (ARDS). So, let’s get started.

Management

Attempts should be made to establish the cause of ARDS and institute the specific therapy to treat it, if treatable (sepsis aspiration, trauma).
The other steps of management are:

1. General measures:
(a) Procure pulmonary and systemic I.V. access for haemodynamic monitoring and fluid therapy.
(b) Arterial O, saturation and arterial blood gas analysis must be monitored for progress.
(c) Adequate nutrition should be ensured through enteral feeding.
(d) If sepsis is the cause, empirical antibiotic therapy may be begun followed by specific therapy depending on the culture and sensitivity reports.
(e) Prophylaxis against pulmonary
embolism (anti-coagulants), GI bleed (H, blockers) aspiration (proper position) and infections.

2. Fluid restriction and diuretics: Try to maintain low CVP (<4 mmHg) or PCWP. (<10 mmHg) for few days by fluid restriction and diuretics. This management strategy will minimise the left atrial filling pressure and reduce interstitial oedema. Transfusion of blood or packed red cells is indicated if the patient is anaemic (Hb <7 g%)

3. Oxygen therapy: The simplest method and the lowest inspired fraction of O2 (FiO2) should be used to achieve a PaO2, of 60 mmHg (O2, saturation of about 90%). Initially spontaneous ventilation using a face mask with high flow rate can be used to improve PaO2 without increasing FiO2. If a FiO2 more than 0.6 then PEEP or inverse ratio ventilation (inspiratory time is more than expiratory time) must be considered.

4. Mechanical ventilation (assisted ventilatory support): In ARDS, adequate oxygenation is usually not achieved with these less invasive measures listed above. Mechanical ventilatory support after endotracheal intubation is initially started with volume cycled mechanical ventilators with low tidal volumes. To begin with the initial ventilator setting could be FiO2, as 1.0 (or a lower value that can achieve a PaO2, 60 mmHg and oxygen saturation >90%), low tidal volume 6 ml/kg body weight, PEEP less than or equal to 5 cm of water and inspiratory flow 760 L/min. High PEEP may be applied to increase the lung volume and keep the alveoli open. PEEP is applied in small increments of 3-5 cm H2O up to a maximum of 15 cm H2O to achieve maximum oxygen saturation of >90% with low non-toxic FiO2 levels (<0.6). Ventilatory rate of 20-25 breaths minute is needed to keep PaCO2, and pH normal. A multicentric trial has shown low mortality rates when low tidal volumes were used.
Airway pressure release ventilation
(inverse ratio ventilation) and high frequency ventilation are other newer methods of ventilation to improve oxygenatic.

5. Other ventilatory strategies: High
frequency ventilation or partial liquid
ventilation and lung replacement therapy with extracorporal membrane oxygenation has yield promising results in selected
patients.

6. Prone position: In situations where
maximal PEEP with FiO2, of 1.0 does not supply sufficient oxygen, placing the patient in the prone position has been found helpful.

7. Neuromuscular blockade: In severe ARDS early neuromuscular blockade increased the rate of survival and ventilator free days, hence to be used to facilitate mechanical ventilation.

8. Pharmacological treatment:
i. Corticosteroids therapy: To reduce
potentially deleterious pulmonary inflammation steroids have been used
with limited benefit.
ii. Recent reports using nitric oxide (NO) inhalation (5-80 parts per million) or prostacycline (PGI2) as a selective pulmonary vasodilator showed promising results on initial evaluation. They neither improved survival nor decreased the time of duration of ventilation, hence, not recommended now in ARDS.
iii. Certain antioxidants (N-acetylcysteine, glutathione, vitamin E) have been tried
to overcome free radical-mediated
injury without much success.

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