Viva 6

As the duty locum Intensivist you have been called to urgently review a patient on the medical ward of a small private hospital. The patient, Jane, is a 62-year-old female who was admitted to the ward yesterday with shortness of breath and leg swelling.

She presents with shortness of breath often, and has recently been started on a bronchodilator.

A local GP registrar was on the ward reviewing another patient and noticed that Jane was working very hard to breathe. The registrar emergently intubated her prior to your arrival.

You arrive on the ward 10 minutes post intubation. The registrar and a ward nurse are hand-ventilating Jane, who is hypoxic – O2 saturations 85% - and hypotensive – BP 75/50 mmHg.

The registrar and nurse are with the patient and you have been called to assist.

Please interpret this arterial blood gas result (FiO₂ 100%)

(After an initial period of slightly embarrassed simulation, this turned into a discussion of mechanical ventilation strategies for asthma. The gas was never part of this viva; it has been introduced so that the solitary viva coordinator is able to do a session on their own. Also, Jane was initially 32 yars old. The age was modified to turn this into a COPD discussion)

Gas interpretation:

• Mild acidaemia
• Severe hypoxia (A-a gradient 566; P/F ratio is 64)
• Metabolic alkalosis
• Respiratory acidosis (expected CO₂ is around 49)
• Hyponatremia

What are the possible explanations for these findings?

• Acidaemia - probably due to the respiratory acidosis
• Severe hypoxia (A-a gradient 566; P/F ratio is 64) - 
  • Differentials are broad: pneumonia, aspiration, PE, pulmonary oedema
• Metabolic alkalosis
  • Chronic adaptation to hypercapnea
  • Diuretic therapy
• Respiratory acidosis (expected CO₂ is around 49)
  • Tiring 
• Hyponatremia
  • Diuretic therapy (classically, a thiazide or a loop diuretic)

Describe how you would you assess the patient.

ABCDE approach may be attempted here. An appropriate series of steps:

Immediate assessment:

A) Make sure the ETT is in correct position by auscultating the chest

B) Ensure the manual resuscitator bag is connected to wall oxygen and the reservor is inflating well

C) Assess the cardiovascular system quickly by physical examination, looking for signs of heart failure

D) Review the recently administered medications.

Some collateral history would be useful from bystanders, and background history from the notes.

What changes would you make to her management?

The main issues are with the ventilator:

• Decrease PEEP (to nil, potentially)
• Decrease respiratory rate
• Decrease the I:E ratio
• Decrease the inspiratory rise time (i.e. make it more "steep"
• Aim for a tidal volume of 5-6ml/kg

Also: because of the evidence of bronchospasm, one might want to start her on corticosteroids.

What further investigations would you like to perform?

• ABG
• EUC / CMP / FBC / CRP /BNP
• Chest Xray - looking for pneumonia
• Transthoracic echo - to assess the contribution from heart failure
• Blood/sputum cultures
• Urinary pneumococcal and legionella antigens
• Atypical pneumonia serology

The family offer some background history. They tell you Jane has "smoker's chronic lung disease".  How would you assess the severity of this?

Historical features:

• exercise tolerance
• breathlessness with everyday activities
• presence of chronic cough
• high volume of sputum, suggestive of bronchiectasis
• haemoptysis, suggestive of malignancy
• home O2 requirement
• home CPAP requirement
• pattern of bronchodilator use
• pattern of steroid use
• frequency of hospitalisations
• previous mechanical ventilation
• anorexia and weight loss

Examination:

• features of malnutrition
• features of obesity (sedentary lifestyle)
• features of chronic steroid use
• central cyanosis
• breathlessness at rest
• hyperexpanded chest
• degree of air entry
• signs of right heart failure

The family asked you whether Jane has "a good chance". What indices are you aware of to help predict mortality in COPD?

Parameters such as the BODE index can be used:

Variable	Points on the BODE index
	0	1	2	3
FEV1 (% of predicted)	>65%	50-64%	36-49%	<35%
Distance walked in 6 minutes	<350	250-350	150-249	<149
MMRC dyspnoea scale	0-1	2	3	4
Body mass index (BMI)	>21	<21

- Among the most severe group, there is a 50% mortality at 36 months.

Another is the MMRC breathlessness scale,  a subjective report of how breathless the patient feels; 0 is "doin fine" and 4 is "can't leave the house".

The family inform you that Jane had fevers before coming to hospital. How does this alter your investigations or management?

• Streptococcus pneumoniae and Haemophilus influenzae account for 80% of the pathogens. The rest are atypicals and viruses, such as Moraxella,Mycoplasma pneumoniae, Pseudomonas, RSV, adenovirus, influenza and parainfluenza. There may or may not be an actual pneumonia (the left side of the chest was quiet)
• Antibiotics may benefit as this may be an infective exacerbation

Apart from antibiotics, what will your non-ventilator management consist of for the following days?

• Bronchodilators (salbutamil and anticholinergics)
• Methylxanthines
• Steroids
• Antibiotics
• Management of any underlying heart failure

Disclaimer: the viva stem above may be an original CICM stem, acquired from their publicly available past papers. Or, perhaps it is a slightly altered version of the original CICM stem. Or, it is a completely original viva stem, concocted by the monstrously amoral author of Deranged Physiology for nothing more than his own personal amusement. In either case, because the college do not make the main viva text or marking criteria available, almost everything here has been confabulated. It might sound like a plausible viva and it could be used for the purpose of practice, but all should be aware that it does not represent the "true" canonical CICM viva station.