A 44 year old man, with morbid obesity (175 cm tall and 210 kg) presents to the Emergency Department with respiratory failure.
He is obtunded with an arterial blood gas (ABG) showing
- pH 7.25
- Pa C02 82 mmHg
- PaO2 53 mm Hg
CXR reveals cardiomegaly and clear lung fields.
(a) Describe your management of this problem in the first 24 hours.
Management includes history and examination, investigations (appropriate and interpreted) and ongoing therapy (including triage, monitoring, pharmacology and non-pharmacological inventions).
ABG confirms hypoxic and hypercapnic respiratory failure (on some unspecified level of supplemental oxygen), with an acute on chronic respiratory acidosis (with a compensatory metabolic alkalosis [calculated HC03 of 36]).
Cardiomegaly could be due to an AP portable, semi-erect film. but the cardiac enlargement should not be discounted(? cardiomyopathy,?? pericardial effusion). Obtundation should not be assumed to be due to the hypercapnia.
The goal of overall management should be to ensure safety of the patient (attention to ABCs), support the patient (posture: upright or on side, consider non-invasive ventilatory support), and identify and treat any specific reversible causes.
History and examination should suggest/exclude many diagnoses including: ischaemic heart disease, cardiac failure (left and right sided), chronic obstructive lung disease, venous thromboembolism, respiratory tract infection, CNS disorder (stroke/haemorrhage), diabetes (and DKA/Hyperosmolar Hyperoncotic Non-ketotic Coma) -·er other endocrine -problem (eg. hypothyroidism) and the potential for drug related problems (prescribed or over the counter eg.codeine).
Simple investigations should be ordered and reviewed to assist above differential diagnosis and assist treatment (eg. blood glucose, electrolytes, full blood examination, ECG) and to confirm suspicions.
Treatment should be directed at clinical suspicions (appropriate antibiotics [drugs and doses], heparin or equivalent [prevention or treatment], bronchodilators [including steroids] etc.). Discussion.of attempts to prevent intubation should be provided (difficulty with intubation, and risks of ventilation higher). Non-invasive ventilation is covered in short answers, but general principles should be mentioned.
Management will consist of attention to the ABCs with simultaneous rapid focused physical examination, and brief history.
- Assess the need for intubation
- Assess the difficulty of intubation, and access relevant specialty staff to assist, as well as the equipment required
- Maintain airway by basic adjuncts including oropharyngeal and nasopharyngeal airways
- Maintain normoxia by supplementing high flow oxygen
- Progress to NIV as soon as it becomes avaliable, if airway reflexes are intact and there are no other contraindications
- ventilator settings need to be adjusted to compensate for increase mass of the chest all, and increased upper airway resistance
- Ideally, ventilation should remain non-invasive
- TTE to assess chamber volume and contractility, and to rule out pericardial effusion
- Secure venous access
- Specific management
- history to determine aetiological cause of the hypercapnic hypoxic respiratory failure
- consider drugs with potential to cause sedation
- administer ny appropriate antidoes
- consider sepsis and pneumonia as a cause of gas exchange defect
- commence antibiotics
- Correct cardiac failure with appropriate use of vasoactive drugs, afterload reduction and preload optimisation
- Consider CTPA if allowed by CT scanner aperture, and V/Q scan if not.