Typhoid and Parayphoid fever

Typhoid and Paratyphoid fever manifest as a diarrhoeal enteric fever that is caused by the gram negative bacilli Salmonella typhi and S. paratyphi (serovars A,B,C).  Paratyphoid fever causes similar symptoms but is generally more benign and from here we will refer to both as Enteric fever.

Enteric fever may be responsible for up to 3% of ill travellers with a febrile illness (Reference - N Engl J Med 2006 Jan 12;354(2):119).  Between 1985 and 1994, 2445 patients were reported to the CDC in the USA:

• Mortality 0.4%
• international travel within the previous 30 days was seen in 72% of cases
• 6 countries accounted for 80% of cases - Mexico, India, Philippines, Pakistan, El Salvador, Haiti
• Reference - Arch Intern Med 1998 Mar 23;158(6):633

The human is the only host for these GNBs, and they live in the colon in the active state but can be carried within the gallbladder.  They are transmitted via the faeco-oral route.

Patients usually present as a returned traveller from SE Asia with variable symptoms including diarrhoea or constipation, abdominal pain, rash, and prolonged fever.  Examination may reveal high temperature, tender splenomegaly, or "Rose spots" (evanescent abdominal papules).

Differential diagnosis includes:

• Non-infectious gastroenteritis
• Malaria
• Dengue
• Leptospirosis
• Measles
• Chikungunya

The diagnosis is made on the basis of Blood Cultures and serologic testing.  Unfortunately the Widal Test (serology) is negative within the first week.  The untreated prognosis is death (10 - 30%) or resolution within 4 weeks, complications manifesting as sepsis, gastrointestinal haemorrhage and perforation, encephalitis, and metastatic abscesses.

Prevention with parenteral vaccination (Typherix - GSK, in Australia) or oral vaccination (Vivotif - CSL, in Australia) may be indicated for travellers to an endemic area.  Treatment is with fluoroquinolones or 3rd-generation cephalosporin, however Ciprofloxacin resistance is becoming an increasing problem in the sub-continent and SE Asia.  Susceptibility tests should be performed.

Caring for the critically ill

Give your patient a fast hug every day!

This mnemonic can be used to reduce errors and apply protocol-driven, evidence-based medicine at the bedside.  It can be applied daily on ward rounds in the ICU, or used as part of the package of care delivered in the ED on arrival of the critically ill patient

F  -  feeding
A  -  analgesia
S  -  sedation
T  -  thromboembolism prophylaxis
H  -  head of bed elevation
U  -  ulcer prophylaxis
G  -  glucose control

Vincent JL, Crit Care Med 2005 Vol. 33, No. 6

Penetrating neck injuries

General principles
Assume the knife/etc. is of any length, penetrated to any depth, and hit any structure. 
Apply pinpoint (focal) pressure if needed, not general pressure.
If airway slashed open, intubate it if able!
Gunshot wounds are very different to stab wounds due to cavitation injury.


Examination

Neck Zones

• Zone 1: clavicles to crycoid
• Zone 2: crycoid to angle of jaw
• Zone 3: above angle of jaw

Don't forget to check the hairline, ears etc.

Management
Traditional workup was to explore all Zone 2 injuries and angiography/panendoscopy to Zone 1 and 3.  Forget this. 
Remember the hole doesn't necessary correlate with the injury.  Does the patient have hard signs of vascular or aerodigestive tract injury?  If so, there's no role for radiologic investigation, these patients need to go to the OT.
However, the vast majority of patients have soft signs - these patients need CT angiography.  CT angiography has a Sensitivity of 100% and Specificity in the 90% (in the absence of fragments causing artifact, such as bullets).
Should you probe the wound?  Probably not.

Evidence Based Medicine - Asking an answerable question

We are regularly confronted with clinical situations where we do not have complete knowledge of the subject.  Part of the process of improving our knowledge involves being able to ask an answerable question.  A good clinical question has four components (PICO):
1.  Patient
     -  What are the important characteristics?
2.  Intervention (or exposure)
     -  Drug/test/procedure/environmental exposure
3.  Comparison
     -  What are you comparing the intervention to?
4.  Outcome
     -  What are you hoping to measure?

Clinical questions are commonly assessing therapy, harm, diagnosis, or prognosis.

Clinical scenarios

1. I was recently called to see a patient with an exacerbation of fluid overload in the setting of severe dilated cardiomyopathy (EF 18%, normal right heart).  The medical registrar felt that the patient needed a period of cardiac monitoring in the HDU.  I noted he had previously been considered for an AICD.  This begs the question (assessing a therapy):
• In adult patients with dilated cardiomyopathy and low ejection fraction, does the insertion of an AICD reduce the incidence of arrhythmogenic sudden cardiac death, compared with medical management?
2.  I recently attended the ED to see a patient transferred from a small community via RFDS where he had been diagnosed with NSTEMI.  Despite improvement in his (non-thrombolysable) ECG changes and adjunctive medical management (thrombin inhibition with Heparin, anti-platelet agents, GTN infusion, and analgesia) he had ongoing ischaemic-sounding chest pain.  I considered GP IIb/IIIa inhibitors and wondered (assessing harm):
• In adult patients with unstable acute coronary syndrome, does the addition of a GP IIb/IIIa inhibitor to standard medical treatment result in increased risk of major bleeding events or death?

Hopefully at some point I'll find the time to answer these questions!

Japanese Encephalitis

Kunjin virus has been detected in sentinal chickens near Darwin!

Japanese Encephalitis Virus (JEV) belongs to the Japanese encephalitis serocomplex made up of 10 flavivures which include Kunjin, West Nile, Murray Valley and St. Lous encephalitis.  It is the most significant arboviral encephalitis worldwide.

JEV is a systemic infection transmitted by the bite of mosquitoes in endemic areas in asia, primarily Culex tritaeniorhynchus (Aedes have also been implicated).  After infection a viraemia develops, with resulting inflammation of heart, lungs, liver and reticuloendothelial system.  The infection is usually cleared prior to CNS infection, resulting in subclinical disease.  When CNS invasion does occur the virus has a direct toxic effect on brain cells and in particular neural progenitor cells.  The infection can involve thalamus, basal ganglia, brain-stem, cortex, cerebellum and hippocampus

Symptomatic cases are approximately 1 in every 150,000 person-months spent in an endemic area, however only 1 in every 250 infections results in clinical disease.  Mortality with good intensive care support approximates 5 - 10% and may exceed 35% in less well-developed areas.  Up to 50% of survivors have major neurologic sequelae at 1 year.  Previous Dengue infection may have a protective effect.

Incubation period is 6 - 8 days.  Prodrome is characterised by an influenza-like illness with fevers, headache and myalgias.  Subsequent altered mental state can range from confusion to coma.  Seizures appear in 66% of cases.  Tremor or other involuntary movements are common.  Neurologic signs may vary but can include hypertonia and hyperreflexia.  Papilloedema develops in less than 10% of patients, and 33% have cranial nerve findings.  Extrapyramidal symptoms are common.

Test both blood and CSF for JEV IgM Ab.  MRI and CT scan often show bilateral thalamic lesions with haemorrhage.  Treatment is supportive, and may include interventions for raised ICP.  Steroids have not shown benefit.  JEV vaccine exists for prevention, has a risk of hypersensitivity reaction (such as angioedema) which can be delayed up to 10 days.

Information from eMedicine's Japanese Encephalitis page here

Welcome to VicCritCare

Hello, I'm Dr John Dyett and I'm an Emergency and Intensive Care Doctor training in Melbourne, Australia.

This Blog will be a collection of posts relating to the science and practice of Medicine, and is designed to store the information I am unable to contain within my head!