Question 1a

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.

[Click here to toggle visibility of the answers]

College Answer

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.

  • Airway
    • 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
  • Breathing
    • 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
  • Circulation
    • ECG
    • 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.