ICU Fellowship Vivas – Anti-fungal treatment, Failure to Wean and Pacemaker troubleshooting

Written by – Dr Madhuri Anupindi

1. 26M who remains ventilated one week after an MVA in which he sustained severe intra-abdominal and head injuries as well as multiple fractures. He underwent an immediate trauma laparotomy and required a splenectomy and repair of a bowel perforation. He has had persistent fevers since admission and has received a course of Tazocin. He is currently receiving low dose noradrenaline and TPN via a non tunnelled CVC. He has a history of IVDU. Give a differential diagnosis for the fever in this patient.

Multiple causes both infectious and non-infectious.

Infectious:

• Concern regarding MRO or fungal infection given persistent fevers despite tazocin
  • ESCAPPM organisms may not be covered
  • Multi resistant gram-negative organisms
  • MRSA/VRE infections
  • Fungal infection
  • Penicillin resistant organisms
• Lack of/reduced penetration or inadequate dose despite bacterial sensitivity
  • Intra-abdominal collections
  • Meningitis
  • Infective endocarditis
• Location may be multiple: CNS, sinusitis, skin, line, VAP, intra-abdominal, joint, UTI, infective endocarditis
  • Also asplenic so at risk of infection by encapsulated organisms

Non-infectious:

• Drug related
  • Serotonin syndrome
  • Withdrawal
  • Drug fever: antibiotics
• Inflammatory
  • Acalculous cholecystitis
  • Seizures secondary to head injury
  • Aspiration pneumonitis
  • Pancreatitis
• Transfusion-related
• Vascular
  • DVT/PE
  • Ischaemic bowel
  • Intracranial haemorrhage  worsening of the initial injury
• Endocrine
  • Overfeeding

What would your assessment of this patient involve?

The assessment would involve a thorough history, examination and targeted investigations in order to determine the cause of this patient’s fever and to progress this patient’s management.

Assessment: history, exam, investigations

• History:
  • Trauma-related: the extent of his injuries and treatment received, recent CT scans
  • Fever related: recent microbiological tests, age of current central lines, trend of fever and vasopressor requirement, dates of antimicrobial treatment, post-splenectomy prophylaxis, localising symptoms of fever, other potential culprit medications and transfusions given
  • Background: details about IVDU, any other drug/alcohol use
  • Trajectory in ICU: ventilator requirements, vasopressor requirement, organ function, screening dopplers, nutrition
• Examination
  • Vital signs
  • Localising signs of fever – meningism, line sites, respiratory exam/sputum, abdomen, signs of DVT
• Investigations
  • Bedside: ECG, ABG, TTE
  • Bloods: full septic screen – peripheral and central cultures, sputum/urine culture, organ function (UEC, LFT), FBC, consider inflammatory markers PCT/CRP, lipase, serum galactomannan
  • Imaging: CXR, consider CT pan scan/TOE depending on findings
  • Further investigations e.g. LP, US abdomen, bronchoscopy would depend on the results of the assessment

A set of peripheral blood cultures is positive for Candida Glabrata. Outline your specific management.

Treat candidemia:

• Use Echincandin: Anidulafungin 200mg IV first dose then 100mg daily (as species demonstrates a high resistance to azoles)
• May be able to de-escalate to fluconazole if it found to be a susceptible species
• Daily blood cultures until culture results are negative
• Anti-fungal treatment for 14 days after the culture results are negative if there are no metastatic complications of the infection. If there are metastatic complications such as liver abscess then requires 4 – 6 weeks of therapy

Identify source:

• Check findings of investigations including peripheral/central cultures, recent imaging, sputum/urine cultures
• Low threshold for repeat imaging if concerns regarding metastatic infection
• Change CVC, send previous CVC tip for culture and take new blood cultures with insertion of CVC

Evaluate for complications and treat

• Endophthalmitis: should have dilated fundoscopic examination by ophthal
• Endocarditis: should have an echocardiogram
• Can also get
  • Arthritis – inspect joints
  • Pulmonary candidiasis: may have nodules on CT surrounded by a halo
  • Hepatic and splenic (not in this patient) abscesses: may see on CT

What are the risk factors for invasive non-Albicans Candidiasis?

• Prolonged ICU stay
• Exposure to broad-spectrum antibiotics
• Exposure to fluconazole
• Central venous catheter
• TPN
• Diabetes
• Renal failure
• Repeated abdominal surgery
• Immunosuppression: malignancy, steroid use, stem cell/solid organ transplant, HIV

Briefly outline the role of empirical antifungal treatment in the critically ill.  

The role of empirical antifungal treatment in the ICU population has not been fully elucidated. Evidence such as the EMPIRICUS trial has shown no significant benefit in patient-centred outcomes.

EMPIRICUS trial 2016:

• RCT of 260 mechanically ventilated patients with at least one organ failure and new ICU acquired sepsis of unknown origin
• Empiric treatment with Micafungin vs placebo for 2 weeks
• No statistically significant difference in 28-day infection-free survival
• Micafungin group had a lower incidence of new proven invasive fungal infections

There are multiple unanswered questions in regards to; the specific patient subgroups that may benefit from the commencement of empiric antifungal therapy, the criteria for commencement and the optimal timing. The Australian Society for Infectious Diseases Consensus Guideline recommends empiric antifungal therapy for clinically unstable haematology patients.  In clinical practice, I rarely commence empiric antifungal therapy, except in patients who have multiple risk factors for invasive candidiasis and have a high-risk event such as an oesophageal rupture, or who have multiple risk factors and have a deteriorating clinical state despite appropriate antibiotic therapy.

2. 75F previously fit and well admitted with hypoxic respiratory failure due to CAP. She has developed multi-organ failure over the first 3 days and required extensive support. Her cardiorespiratory status gradually improved but now she remains ventilator-dependent at day 10. What might be the specific barriers to her weaning from the ventilator and how might they be managed?

There are multiple potential specific barriers in this patient including neurological, metabolic, gastrointestinal, cardiac and respiratory.

CNS:

• Neuropsychiatric: delirium, anxiety, pain
  • Minimise sedation and multiple pharmacological agents
  • Adequately treat pain
  • Optimise sleep-wake cycle
  • Screen and treat delirium
• Decreased neuromuscular capacity especially critical illness polymyoneuropathy
  • Adequate nutrition
  • Physiotherapy
  • Avoid steroids/NMBs
  • Optimise electrolytes

Metabolic/renal

• Increased demand: hypoxemia, fever/sepsis, severe anaemia
  • Treat infections, paracetamol for fever, correct anaemia, treat any other causes of hyperdynamic circulation
• Metabolic acidosis
  • Treat cause
• Renal failure:
  • ?requires dialysis

GIT

• Abdominal distension
  • Aperients, NG decompression, physio
• Overfeeding
  • Optimise nutrition, decrease carbohydrate
  • Optimise electrolytes

Cardiac:

• New ischaemia, arrhythmias or dysfunction
  • Assess and diagnose ECG/TTE
  • Treat myocardial dysfunction
• Fluid overload
  • Optimise fluid balance: diuretics, concentrated feed, drain effusions

Respiratory

• Increased resistance: bronchospasm, secretions
  • Consider tracheostomy, humidification, physio, bronchodilators, bronchoscopy for the removal of secretions
• Decreased compliance
  • Appropriate ventilator settings, treat lung disease, sit up

List the complications of prolonged invasive mechanical ventilation

Anatomical:

• Laryngeal or tracheal injury
• Bronchial injury from suctioning
• Laryngeal or tracheal stenosis
• Tracheomalacia

CNS

• Sleep disturbance
• PTSD, depression, anxiety and other neuropsychiatric complication ns
• Muscle wasting, critical illness polymyoneuropathy

Infections

• Ventilator-associated pneumonia
• Line infections, sinusitis
• Multi-resistant organism colonisation

GIT

• Swallowing dysfunction
• Mucosal ulceration

Other

• DVTs
• Pressure areas

3. 68M who is 2 days post AVR for AS with good LVF. Recovery was uneventful other than a junctional bradycardia of 40bpm which required VVI pacing at 80bpm via an epicardial RV wire placed at the time of surgery. His nurse asks for your help as his BP has been falling. He is on nasal prongs and remains conscious. His bedside monitor shows pacemaker spikes with no corresponding QRS complex. How would you approach this problem? 

This pacemaker is failing to capture which is a potentially life-threatening situation although currently the patient’s level of consciousness and respiratory function seems to be stable. Ongoing management will depend on whether he is haemodynamically stable or unstable.

If unstable:

• Call for help: ICU team/cardiothoracic, arrest trolley/airway trolley
• Concurrent assessment and resuscitation
  • Evaluate the cause of falling BP: is it just a rhythm issue?
    • Current HR, BP, RR sats and their trajectory, temperature
    • Chest drains still in situ? Output
    • ECG, ABG, consider TTE, CXR, electrolytes
    • Current medications
  • Optimise rhythm
    • Apply transcutaneous pads: pace externally if required  give patient sedation first and be prepared for intubation
    • Troubleshoot pacemaker:
      • Emergency mode  Increase output to maximum, Place pacing on DDD (if also has atrial leads) or VOO
      • Check all leads, connections, batteries and replace if faulty
      • Try reversing polarity
      • Converting bipolar to a unipolar circuit with cutaneous pacing stitch
    • Consider pharmacotherapy: isoprenaline
    • PA sheath still in situ? Can potentially float a pacing swan or temporary pacing wire when patient is stable
    • Optimise electrolytes
  • Optimise haemodynamics and treat the specific cause
    • If not purely a rhythm issue
      • Fluid/blood, vasopressors, inotropes  depending on findings but less likely given good LVEF and uneventful post-op course

If stable:

• Evaluate and treat potential other causes of falling blood pressure if identified
• Optimise pacing
  • What is patient’s underlying rhythm and is it maintaining sufficient cardiac output i.e. does the patient still require pacing?
  • Check all leads, connections, batteries of pacemaker and replace if faulty
  • Increase pacemaker output until capture achieved
    • If not achieved and patient still requires pacing then can try reversing polarity, notify cardiothoracics, apply transcutaneous pads, consider transvenous pacing or pharmacotherapy
    • If rapidly escalating capture threshold then apply pads, notify cardiothoracics and have contingency plan for pacing failure
  • Check sensitivity
  • Optimise temperature and electrolytes

What are the causes of failure to capture?

• Wire malposition
• Acid Base abnormalities
• Hypo or Hyperkalaemia
• Hyperglycaemia
• Drugs e.g. B blockers, calcium antagonists
• Fibrin deposition on the wire