Viva 4

You have been asked to review a 56-years-old female in recovery, who became hypoxic post bronchoscopy. Bronchoscopy was done to investigate a history of 2 weeks increasing shortness of breath, associated with bilateral chest infiltrates on chest X-ray. She is currently intubated and ventilated, with a SpO2 of 88% on FiO2 1.0. 

Her respiratory function tests from one week prior to admission are tabulated below: 

Pre-Bronchodilator (BD)

Post- BD

Test

Actual

Predicted

% Predicted

Actual

% Change

FVC (L)

1.73

4.37

40

1.79

4

FEV1 (L)

1.57

3.65

43

1.58

0

FEV1/FVC (%)

91

84

88

- 3

RV (L)

1.01

1.98

51

TLC (L)

2.68

6.12

44

RV/TLC (%)

38

30

DLCO* corr

5.13

32.19

16

DLCO/VA

1.00

5.12

19

*DLCO is measured in ml/min/mmHg

List the differential diagnosis of hypoxia post bronchoscopy in this patient, and outline your management.

Diffuse pulmonary infiltrates in this patient could be caused by any damn thing:

Differential Diagnosis for Diffuse Bilateral Pulmonary Infiltrates

Vascular:

  • Pulmonary haemorrhage
  • Cardiogenic pulonary oedema

Infectious

  • Bacterial
  • Viral
  • Fungal
  • PJP

Neoplastic

  • Lymphangitis
  • Infiltrative neoplasm

Idiopathic

  • ARDS
  • Idiopathic pneumonia syndrome

Drug-induced

  • Eosinophilic pneumonitis
  • BOOP
  • Alveolar haemorrhage
  • Methotrexate-induced

Autoimmune

  • Goodpastures (haemorrhagic)
  • Rheumatoid pneumonitis
  • TRALI
  • Graft vs host disease in BMT
  • Engraftment syndrome
  • ATRA syndrome

Traumatic / postoperative

  • Bilateral atelectasis
  • Pulmonary contusions
  • Chemical pneumonitis
Can you explain the meaning of the variables in this pulmonary function test panel? What conclusion does this panel suggest, regarding the patient's respiratory function?

FEV1 is the forced expired volume over 1 second, and is a measure of maximal air flow. A decreased FEV1 may mean either an obstructive pattern of lung disease, or a diminished expiratory effort (eg. in a patient who has some sort of myopathy or neuropathy).

FVC is the forced vital capacity, from maximal inspiration to maximal expiration. A decreased FVC may reflect poor respiratory effort.

FEV1/FVC ratio is a measure of airway resistance. A FEV1/FVC ratio less than the 5th percentile of predicted suggests obstructive airways disease

PEF is the peak expiratory flow rate. A low PEF suggests obstructive disease.

FRC is the functional residual capacity. A high FRC suggests hyperinflation (eg. in asthma) or large volumes of dead space (eg. emphysema)

RV is the residual volume. As with FRC, a high RV suggests hyperinflation or bullous dead space.

TLC is the total lung capacity. A high TLC may coexist with a very poor FEV1 and FVC in emphysema. A low TLC (below the 5th percentile of predicted) suggests restrictive lung disease, such as pulmonary fibrosis.

DLCO is the diffusing capacity for carbon monoxide, a measure of the efficiency of the lung as a gas exchange surface.  Normal  spirometry and lung volumes associated with decreased DLCO may suggest anaemia, pulmonary vascular disorders, early interstitial pulmonary fibrosis or early emphysema. It is expressed in ml/min/mmHg, and a value below 40% of predicted suggests a severe diffusion defect. DLCO may also be decreased if there is reduced lung expansion (i.e. a reduced TLC).

KCO (DlCO/VA) is the transfer coefficient for carbon monoxide. It is calculated as the DLCO per unit of alveolar volume. As such, the KCO will not be confused by changes in lung volume, and is a more faithful representation of the gas diffusion efficiency.

What other investigations would inform your management of this patient?

The candidate may suggest a whole series of possible investigations:

  • Bloods, which might include a normal panel 
  • BNP to discriminate cardiac from noncardiac causes
  • Procalcitonin to discriminate bacterial from viral or nonifgective
  • Cultures, including urinary antigens and atypical serology
  • A "vasculitic screen" might be asked for
  • Ultrasound of the lung to look for pulmonary oedema
  • A high-resolution CT or a CTPA
  • A TTE
The TTE was reported as "severe pulmonary hypertension" and moderate RV systolic dysfunction with moderate TR.
What is the upper limity normal pulmonary arterial pressure?

Pulmonary arterial pressure is 12-16 mmHg in the normal population. Pulmonary hypertension is diagnosed when the pressure exceeds 25mmHg at rest, or 30mmHg with exercise.

What are the possible causes of pulmonary hypertension? How do you classify them?

In brief, there are 5 major groups of disease which fall under the pulmonary hypertension heading:

  1. Pulmonary arterial hypertension 
    • associated with connective tissue disease
    • HIV
    • Congential or heriable
    • Drug-related
    • Due to portal hypertension
  2. Pulmonary hypertension due to left heart disease
    • ​LV systolic or diastolic dysfunction
    • Valve disease
    • Congential cardiomyopathies
  3. Pulmonary hypertension due to lung disease or hypoxia
    • COPD
    • Idiopathic pulmonary fibrosis
    • ​​OSA/obesity hypoventilation syndrome
    • Chronic exposure to high altitude
  4. Pulmonary hypertension due to chronic PE​​
  5. Pulmonary hypertension due to "unclear multifactorial mechanisms"
    • Myeloproliferative diseases
    • Haemolytic anaemias and MAHA
    • Sarcoidosis, pulmonary histiocytosis
    • Tumour obstruction
    • Fibrosing mediastinitis
Pulmonary Arterial Hypertension

Idiopathic PAH

  • Familial PAH
  • BMPR2 mutations (a member of the transforming growth factor β signaling family)

Drug and toxin induced PAH

  • Definite association: aminorex, fenfluramine, dexfenfluramine, toxic rapeseed oil
  • Possible association: cocaine, phenylpropanolamine, St Johns Wort, chemotherapy agents, SSRIs

Connective tissue disease

  • Systemic sclerosis
  • SLE
  • Sjogren syndrome
  • polymyositis
  • rheumatoid arthritis
HIV infection
  • clinical, hemodynamic, and histologic characteristics similar to those seen in idiopathic PAH
Portopulmonary hypertension
  • 2% to 6% of patients with portal hypertension have PAH
  • Pulmonary vascular resistance (PVR) is usually normal in these cases
Congential heart disease
  • systemic-to-pulmonary shunts
  • Eisenmenger syndrome
Schistosomiasis
  • Embolic obstruction of pulmonary arteries by schistosoma eggs
  • local vascular inflammation as a result of impacted schistosoma eggs
Chronic hemolytic anemia
  • sickle cell disease (SCD)
  • thalassemia
  • hereditary spherocytosis
  • stomatocytosis
  • microangiopathic hemolytic anemia
Left heart disease
  • LV failure
  • Mitral valve disease
Alveolar hypoxia
  • Alveolar hypoxia as a result of lung disease
  • Alveolar hypoxia due to impaired control of breathing (eg. OSA)\
  • Alveolar hypoxia due to residence at high altitude
Thromboembolism
  • obstruction of pulmonary arterial vessels by thromboemboli, tumors, or foreign bodies
Pulmonary hypertension due to unclear or multifactorial aetiologies
  • polycythemia vera
  • essential thrombocythemia
  • chronic myeloid leukemia
  • sarcoidosis
  • Langerhans histiocytosis
  • glycogen storage diseases
  • Gaucher disease
  • mediastinal fibrosis
What extrapulmonary diseases might be associated with pulmonary hypertension?
  • Rheumatoid arthritis
  • Sarcoidosis
  • Amyloidosis
  • Scleroderma
  • CREST syndrome
  • polycythemia vera
  • essential thrombocythemia
  • chronic myeloid leukemia
  • Langerhans histiocytosis
  • glycogen storage diseases
  • Gaucher disease
  • mediastinal fibrosis
You suspect that this patient suffers from some sort of connective tissue disease, either CREST syndrome or scleroderma. What are the cardinal features of CREST syndrome?
  • Calcinosis
  • Raynaud's phenomenon
  • Oesophageal dysmotility
  • Sclerodactily
  • Telangiectasia
And what are the cardinal features of scleroderma?

Cutaneous manifestations

  • Skin thickening
  • Oedema of the digits
  • Sclerodactyly
  • Pitting ulceration, particularly at the fingertip
  • Calcinosis over joints
  • Telangiectasia
  • Raynauds phenomenon

Other associated clinical features:

  • Sjogren syndrome
  • Limited mouth opening
  • Signs of pulmonary hypertension (loud P2, etc)
  • Cardiac arrhythmias
  • Features of heart failure
  • Features of Cushing syndrome due to long term steroids
  • Renal artery bruitts
Are you aware of any tests which might confirm the diagnosis of scleroderma?
  • Anti-centromere antibodies (most associated with pulmonary hypertension)
  • Scl-70 
  • RNA polymerase III
A diagnosis of scleroderma is confirmed with a positive anti-centromere antibody titer. What other organ or systemic issues would you anticipate in an ICU patient with this disorder?
  1. Difficult intubation:
    1. Limited neck extension
    2. Limited mouth opening
  2.   Respiratory involvement:
    1. Pulmonary fibrosis
    2. Restrictive lung disease
    3. Pulmonary hypertension
    4. SpO2 monitoring may be frustrated by poor end-digital perfusion
    5. The rapidly fatal "scleroderma-pulmonary-renal syndrome (SPRS)" may develop, which manifests as a fulminant course of acute normotensive renal failure associated with diffuse alveolar hemorrhage.
  3. Cardiovascular involvement of the disease process:
    1. Cardiac problems:
      1. Arrhythmias,
      2. Myocardial fibrosis (thus, restrictive diastolic failure)
      3. Pericardial stricture (also restricts diastolic filling)
    2. Vascular problems
      1. Difficult vascular access: the skin, being very thick, makes it difficult to palpate vessels (veins and arteries both)
      2. Poor distal perfusion of the extremities, leading to gangrene- as one might expect this is not improved by arterial cannulation.
      3. Poor skin perfusion promotes pressure areas
  4. Neurological sequelae: 
    1. Corticosteroid-associated psychosis
    2. Cerebral vasculitis
  5. Electrolyte disturbances
    1. Hyponatremia and fluid retention due to corticosteroid therapy
    2. Hyperkalemia due to renal failure
  6. Renal involvement
    1. Renal failure, renal artery stenosis
    2. Scleroderma "renal crisis"
  7. Gastrointestinal and nutritional issues
    1. Oesophagitis
    2. Poor gut motility
    3. Decreased feed tolerance
    4. Risk of aspiration.
    5. Risk of oesophageal perforation
    6. Telangiectasia is present also on mucosal surfaces; there is an increased risk of bleeding from upper GI sites
  8. Haematological problems:
    1. Anaemia of chronic disease is coupled with the poor EPO synthesis from damaged kidneys.
    2. Bone marrow function may be suppressed in other ways, particularly if serious immunosuppresants are in use (eg. cyclophosphamide)
  9.     Immunosuppressive therapy
    1. Increased infection risk
How would you manage pulmonary arterial hypertension in this patient?

Pulmonary arterial vasodilators:

  • Short term:
    • Inhaled nitric oxide
    • Inhaled prostacycline
  • Long term:
    • Sildenafil
    • Bosantan
    • Ambrisantant

The candidate should then go on to talk about optimising RV function.
If not, ask them the next question:

How will you manage right heart failure in this patient?

This is straight from the college answer to Question 17 from the second paper of 2009:

Therapy

Advantages

Disadvantages

Volume

Effective, as RV needs a
higher filling pressure. A PA catheter may be useful in guiding volume therapy.

Determination of preload
is problematic, RA pressure may be high in chronic right heart failure and may not be a predictor of volume response. Functional parameters of volume responsiveness not useful in right heart failure

Inotropes and vasopressors

-May be of benefit in RV
infarction where they may increase coronary perfusion pressure
- Some suggestion that levosimendan may improve RV afterload in ARDS

No large scale published
data on any specific inotrope or pressor in isolated RV failure

Afterload manipulation
- Control of hypoxia and hypercapnia and acidosis

reduce PA pressures

Optimal target levels unclear.

Prostaglandins

Reduce pulmonary
pressures

May cause systemic
hypotension, flushing

NO

Improves VQ matching,
improves oxygenation

Met Hb, platelet
dysfunction, requires special delivery systems, not shown to improve mortality

Bosentan

Reduce pulmonary
pressures

No large scale data

Phosphodiesterase
inhibitors - sildefanil

Reduce pulmonary
pressures

No large scale data

Pacing to improve A-V
synchrony

Improves preload

 

Mechanical ventilation

May improve oxygenation
and CO2 transfer and may reduce pulmonary hypertension

Deleterious effects of
IPPV

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. 

References

Pellegrino, Riccardo, et al. "Interpretative strategies for lung function tests."European Respiratory Journal 26.5 (2005): 948-968.

The American Throacic Society has a page which features an excellent bibliography of the articles which support their interpretation standards.

Simonneau, Gérald, et al. "Updated clinical classification of pulmonary hypertension." Journal of the American College of Cardiology 54.1s1 (2009): S43-S54.

Simonneau, Gerald, et al. "Updated clinical classification of pulmonary hypertension." Journal of the American College of Cardiology 62.25 (2013): D34-D41.

Galiè, Nazzareno, et al. "2015 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension." European heart journal (2015): ehv317.

Legerton 3rd, C. W., Edwin A. Smith, and Richard M. Silver. "Systemic sclerosis (scleroderma). Clinical management of its major complications."Rheumatic diseases clinics of North America 21.1 (1995): 203-216.

TUFFANELLI, DENNY L., and R. K. Winkelmann. "Systemic scleroderma: a clinical study of 727 cases." Archives of Dermatology 84.3 (1961): 359-371.

Silver, Richard M. "Clinical aspects of systemic sclerosis (scleroderma)." Ann Rheum Dis 50.suppl 4 (1991): 854-61.

Farber, Harrison W., Robert W. Simms, and Robert Lafyatis. "Analytic Review: Care of Patients With Scleroderma in the Intensive Care Setting." Journal of intensive care medicine 25.5 (2010): 247-258.

Doti, P. I., et al. "Mortality prognostic factors of patients with systemic autoimmune diseases admitted to an intensive care unit." INTENSIVE CARE MEDICINE. Vol. 40. 233 SPRING ST, NEW YORK, NY 10013 USA: SPRINGER, 2014.

Shalev, T., et al. "Outcome of patients with scleroderma admitted to intensive care unit. A report of nine cases." Clinical and experimental rheumatology 24.4 (2006): 380.

Janssen, Namieta M., Dilip R. Karnad, and Kalpalatha K. Guntupalli. "Rheumatologic diseases in the intensive care unit: epidemiology, clinical approach, management, and outcome." Critical care clinics 18.4 (2002): 729-748.

Price, Laura C., et al. "Pulmonary vascular and right ventricular dysfunction in adult critical care: current and emerging options for management: a systematic literature review." Crit Care 14.5 (2010): R169.