Monthly Archives: October 2018

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].

Advertisements

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.

Intraoseous (IO) Meds

Here is a list of medications that can be given via the intraosseous route.

IO meds

Alteplase not included in the list, although there are case reports of tPA given via the IO route.  Tenecteplase can be given IO.

 

 

(Thanks Ben Wee for the info!)