Venous Blood Gas – VBG-ABG correlation

Venous blood gas can be used toestimate systemic CO2 and pH levels.

Possible sites of VBG:

  1. peripheral venous sample (from venipuncture)
  2. central venous sample (from central venous catheter)
  3. mixed venous sample (from distal port of PAC)

Values from VBG:

  1. PvO2 – venous oxygen tension
  2. PvCO2 – venous carbon dioxide tension
  3. pH
  4. SvO2 – oxyhemoglobin saturation
  5. HCO3 – serum bicarbonate

PvCO2, pH, HCO3 – assess ventilation and/or acid-base status

SvO@ – guides resuscitation

PvO2 – no value

 

Correlations:

  1. Central venous sample
    1. pH – 0.03 to 0.05 pH units lower than arterial pH
    2. PvCO2 – 4-5 mm Hg higher than PaCO2
    3. HCO3 – little or no increase
  2. Mixed venous sample – similar tocentral venous sample
  3. peripheral venous sample
    1. pH – 0.02 to 0.04 pH units lower than arterial pH
    2. HCO3 –  1-2 mEq/L higher
    3. PvCO2 – 3-8 mm Hg higher than PaCO2

*varies with hemodynamic stability

 

Reference:

Uptodate.com. (2018). UpToDate. [online] Available at: https://www.uptodate.com/contents/venous-blood-gases-and-other-alternatives-to-arterial-blood-gases?search=venous%20blood%20gas&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1 [Accessed 22 Oct. 2018].

Canadian C-Spine Rules

Capture2

 

References:

Pathlms.com. (2018). [online] Available at: https://www.pathlms.com/ncs-ondemand/courses/6790/sections/9921/slide_presentations/101375 [Accessed 13 Oct. 2018].

Bandiera, G., Stiell, I., Wells, G., Clement, C., De Maio, V., Vandemheen, K., Greenberg, G., Lesiuk, H., Brison, R., Cass, D., Dreyer, J., Eisenhauer, M., MacPhail, I., McKnight, R., Morrison, L., Reardon, M., Schull, M. and Worthington, J. (2003). The Canadian C-Spine rule performs better than unstructured physician judgment. Annals of Emergency Medicine, 42(3), pp.395-402.

Steroid for Meningitis

There is evidence for use of dexamethasone in bacterial meningitis caused by Streptococcus pneumoniae.

Empiric dexamethasone until cultures return is reasonable.

  • reduces hearing loss in children with H. influenza type b meningitis
  • mortality improved in meningitis caused by Streptococcus pneumonia.

 

IDSA guidelines state:  “some authorities initiate dexamethasone in all adults with suspected bacterial meningitis because etiology is not always ascretained at initial evaluation.”

 

DOSE:  dexamethasone 10mg IV q6h x 2-4d ideally 10-20mins before first dose of antibiotic.

PEDS:  0.15mg/Kg q6h x 2-4d for children.

 

Reference:

Gaieski, D., O’Brien, N. and Hernandez, R. (2017). Emergency Neurologic Life Support: Meningitis and Encephalitis. Neurocritical Care, 27(S1), pp.124-133.

Checklist: Endovascular Intervention in Acute CVA

  • Consider giving tPA even if endovascular treatments are being considered
  • Criteria for endovascular therapy with stent retriever:
    Prestroke mRS 0-1
    AIS receiving tPA within 4.5h onset*
    Large vessel occlusion (M1 or ICA)**
    Age >=18y/o***
    NIHSS >=6
    ASPECTS >=6
    Treatment (groin puncture) can be initiated within 76h of symptom onset

*in carefully selected patients with anterior circulation occlusion who have C/I to tPA, endovascular therapy with stent retrievers completed within 6h of stroke onset is reasonable.

**in carefully selected patients with AIS from occlusion of M2 or M3, ACÁ, VA/BA or PCA, endovascular therapy with stent retrievers completed within 6h of symptom onset is reasonable, but benefits are uncertain.

***Endovascular therapy with stent retrievers may be reasonable for patients <18y with AIS with LVO, if treatment can be initiated within6h of symptom onset, but benefits are not established.

NOTE: Delaying endovascular therapy while observing clinical response to tPA is not recommended.

Reference:

Gross, Hartmut, and Noah Grose. 2017. “Emergency Neurological Life Support: Acute Ischemic Stroke”. Neurocritical Care 27 (S1): 102-115. doi:10.1007/s12028-017-0449-9.