Monthly Archives: November 2017

MRI evolution of Cerebral Abscess

img_1682.jpg

 

Reference:

Criner, G., Barnette, R. and D’Alonzo, G. (2010). Critical Care Study Guide. Dordrecht: Springer.

 

 

Advertisements

Pulmonary Artery Catheter Waveforms and Normal Values

As the PAC is inserted, the following waveforms can be observed.

1. When the catheters enters the RA, a CVP tracing is seen – characterized by a and v waves.img_1652

 

 

 

 

 

 

 

 

 

2. As the catheter enters the RV, a sharp increase in systolic pressure is noted.img_1653

3. As the catheter is advanced to the pulmonary artery, an increment in diastolic pressure is seen as well as the presence of a dichromatic notch. img_1654

4. When the catheter is advanced further into the pulmonary artery, and wedged – a sine wave that oscillates with respiration is seen. img_1655

THE RA WAVEFORM:

The RA waveform is characterized by presence of 2 waves: a wave (contraction of the RA) and the v wave (passive filling of the RA).

The x descent represents RA relaxation, which is interrupted by the c wave which represents closure of the tricuspid valve.

The y descent follows the v wave, which signals the opening of the tricuspid valve and exit of blood from the RA to the RV.

img_1656

OVERDAMPING:

The wave below illustrates flushing of the catheter – which results in high pressures in the transducer (1). Flushing stops, and results in fall in pressures and an overshoot (2), and a return to normal waveform.

img_1661

The wave below – overshooting is absent, and the waveform is flattened, which is found in an overdamped waveform. Overdamping can be caused by a kinked catheter, air bubbles, fibrin clot.

img_1662

 

 

 

 

 

CATHETER WHIP.

The graph below illustrate catheter whip – where ventrcicular contractions are transmitted to the PAC.

img_1663

OVERWEDGING:

The arrow indicates when the balloon is inflated. There is a sustained increment in pressure reading.

img_1664

 

 

 

 

ACUTE MITRAL INSUFFICIENCY

Prominent v waves represent blood that enters the LA during ventricular systole due to an incompetent mitral valve.

img_1665

 

 

 

 

TRICUSPID REGURGITATION

Broad c-v waves can be seen.

img_1666

 

 

 

 

 

RV INFARCTION

Marked acute dilatation of the RV occurs. Acute dilatation is limited by the pericardium. Deep x and y descents, resembling the letter W is seen.

img_1667

 

 

 

 

 

MEASURED HEMODYNAMICS VARIABLES:

img_1648

DERIVED HEMODYNAMICS VARIABLES

img_1649

OXYGEN TRANSPORT VARIABLES

img_1650

Reference:

Criner, G., Barnette, R. and D’Alonzo, G. (2010). Critical Care Study Guide. Dordrecht: Springer.

Formulae: Acid-base disorders

img_1647

 

 

Reference:

Criner, G., Barnette, R. and D’Alonzo, G. (2010). Critical Care Study Guide. Dordrecht: Springer.

Pediatric GCS (Glasgow Coma Scale)

img_1646

 

 

 

References

Garvin, R. and Mangat, H. (2017). Emergency Neurological Life Support: Severe Traumatic Brain Injury. Neurocritical Care, 27(S1), pp.159-169.

Checklist: Vascular Work-up for TBI

Don’t forget to assess cerebral vasculature in TBI patients

Imaging with CTA MRA MRV or DSA should be considered in these patients:

1. Penetrating injury

2. Fracture over venous sinus

3. Neurologic deficit unexplained by head CT

4. C-spine injuries such as severe flex ion/ext injury or Fx through transverse foramen

5. Petrous bone fracture

6. LeFort II or II facial fractures

Suspected cause of injury s.a. Aneurysms rupture

7. Near hanging, seat belt abrasions of neck, anterior neck soft tissue swelling (?blunt injury to carotid / vertebral arteries?)

REFERENCE:

ENLS 2017

TIA Management

Low-risk TIA

  • ABCD scores 0-3
  • out patient work-up in the next 1-2 days
  • alternative is to admit
  • begin ASA 81mg or plavix 75 or ASA 25/ER dipyridamole 200mg BID
  • perform carotid imaging: US, CTA, MRA
  • consider TTE (if bilateral infarcts on CT, high suspicion of cardioembolic source and TTE normal – obtain TEE)
  • consider 30d ambulatory cardiac monitor to document cryptogenic Afib
  • smoking cessation
  • Statins:
    • start high-dose statin (atorvastatin 40-80; rosuvastatin 20-40)
    • consider mod intensity statin if >75 y/o (atorvastatin 10-20, rosuvastatin 5-10, simvastatin 20-40, pravastatin 40-80)
  • consider anticoagulation if ECG (+) Afib, calculate CHADS or CHADSVASC and HAS-BLED scores
  • ? Referral to vascular neurologist or cardiologist

 

High-Risk TIA:

  • admit
  • permissive HTN
  • gradually lower BP limits over 24-48h

 

 

Reference:

Gross, H. and Grose, N. (2017). Emergency Neurological Life Support: Acute Ischemic Stroke. Neurocritical Care, 27(S1), pp.102-115.

Criteria for Thrombectomy / Endovascular Treatment of Stroke

Patients eligible for intravenous alteplase should receive intravenous alteplase even if endovascular treatments are being considered

Patients should receive endovascular therapy with a stent retriever if they meet all the following criteria:

  1. prestroke mRS score 0–1,
  2. acute ischemic stroke receiving intravenous alteplase within 4.5 h of onset
  3. causative occlusion of the internal carotid artery or proximal MCA (M1),
  4. age >18 years, (note: there is no upper age limit),
  5. NIHSS score of C6,
  6. ASPECTS of C6
  7. treatment can be initiated (groin puncture) within 6 h of symptom onset

As with intravenous alteplase, reduced time from symptom onset to reperfusion with endovascular therapies is highly associated with better clinical outcomes

When treatment is initiated beyond 6 h from symptom onset, the effectiveness of endovascular therapy is uncertain for patients with acute ischemic stroke who havecausative occlusion of the internal carotid artery or proximal MCA (M1)

In carefully selected patients with anterior circulation occlusion who have contraindications to intravenous alteplase, endovascular therapy with stent retrievers completed within 6 h of stroke onset is reasonable

Although the benefits are uncertain, use of endovascular therapy with stent retrievers may be reasonable for carefully selected patients with acute ischemic stroke in whom treatment can be initiated (groin puncture) within 6 h of symptom onset and who have causative occlusion of the M2 or M3 portion of the MCAs, anterior cerebral arteries, vertebral arteries, basilar artery, or posterior cerebral arteries

Endovascular therapy with stent retrievers may be reasonable for some patients <18 years of age with acute ischemic stroke who have demonstrated large vessel occlusion in whom treatment can be initiated (groin puncture) within 6 h of symptom onset, but the benefits are not established in this age group

Observing patients after intravenous alteplase to assess for clinical response before pursuing endovascular therapy is not required to achieve beneficial outcomes and is not recommended

Endovascular therapy with stent retrievers is recommended over intra-arterial fibrinolysis as first-line therapy

It might be reasonable to favor conscious sedation over general anesthesia during endovascular therapy for acute ischemic stroke. However, the ultimate selection of anesthetic technique during endovascular therapy for acute ischemic stroke should be individualized based on patient risk factors, tolerance of the procedure, and other clinical characteristics

Reference:

Gross, H. and Grose, N. (2017). Emergency Neurological Life Support: Acute Ischemic Stroke. Neurocritical Care, 27(S1), pp.102-115.