Ventilatory Support for Management of Type-II Acute Respiratory Failure

In this article, we will discuss Ventilatory Support for Management of Type-II Acute Respiratory Failure. So, let’s get started.

Ventilatory Support

Ventilatory support consists of maintaining patency of the airway and ensuring adequate alveolar ventilation. Mechanical ventilation may be provided via face mask (noninvasive) or through tracheal intubation.

1. Noninvasive positive-pressure ventilation: NPPV delivered via a full face mask or nasal mask has become first-line therapy in COPD patients with hypercapnic respiratory failure who can protect and maintain the patency of the airway, handle their own secretions, and tolerate the mask apparatus. Several studies have demonstrated the effectiveness of this therapy in reducing intubation rates and ICU stays in and patients with ventilatory failure. A bilevel positive pressure ventilation mode is preferred for most patients.

2. Tracheal intubation: Indications for tracheal intubation include: (1) hypoxemia despite supplemental oxygen, (2) upper airway obstruction (3) impaired airway protection, (4) inability to clear secretions, (5) respiratory acidosis, (6) progressive general fatigue, tachypnea, use of accessory respiratory muscles, or mental status deterioration, and (7) apnea. In general, orotracheal intubation is preferred to nasotracheal intubation in urgent or emergency situations because it is easier, faster, and less traumatic commonly only tracheal tubes with high-volume, low-pressure air-filled cafts should be used. Cuff inflations pressure should be kept below 20 mmHg if possible to minimize tracheal mucosal injury.

3. Mechanical ventilation: Indications for mechanical ventilation include (a) apnea, (b) acute hypercapnia that is not quickly reversed by appropriate specific therapy, (c) severe hypoxemia, and (d) progressive
patient fatigue despite appropriate
treatment.

Several modes of positive-pressure ventilation are available. Controlled mechanical ventilation (CMV; also known as assist-control or A-C) and synchronized intermittent mandatory ventilation (SIMV) are ventilatory modes in which the ventilator delivers a minimum number of breaths of a specified tidal volume each minute. In both CMV and SIMV, the patient may trigger the ventilator to deliver additional breaths. In CMV, the ventilator responds to breaths initiated by the patient above the set rate by delivering additional full tidal volume breaths. In SIMV, additional breaths are not supported by the ventilator unless the pressure support mode is added. Numerous alternative modes of mechanical ventilation now exist, the most popular being pressure support ventilation (PSV), pressure control ventilation (PCV), and CPAP. Complications of mechanical ventilation include migration of the tip of the endotracheal tube, bronchotrauma, respiratory alkalosis, hypotension and pneumonia.

• If PaCO2, continues to rise or patient cannot achieve a safe PaO2, without severe hypercapnia and acidosis, respiratory stimulant (e.g. doxapram 1.5 to 5 mg/min IV infusion) or mechanical ventilation (NIPPV or invasive) may be required. In case of COPD with acute exacerbation, if the patient is alert and the pH is >7.25, patient can be managed on noninvasive intermittent positive pressure ventilation (NIPPV) therapy through nasal or venture masks. If patient is visibly fatigued and has pH <7.25, then early mechanical ventilation will be ideal.

Monitoring for;
• Level of consciousness
• CVP
• Urine output
• Pulse, BP, temperature, respiration
• Urea, creatinine, electrolytes
• Arterial bloodgases
• Pulse oximetry
• ECG, TLC, DLC.

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