The Analysis of Blood Gases
Under some circumstances, such as in ICUs or emergency rooms, it may be convenient to sample venous blood gases (VBGs). Peripheral blood gases can be sampled by standard venipuncture; central venous blood gases through central venous catheters; and mixed
- PDF / 980,807 Bytes
- 14 Pages / 439.37 x 666.14 pts Page_size
- 53 Downloads / 173 Views
The Analysis of Blood Gases
Contents 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8
11.9
Normal Values............................................................................................................... 11.1.1 Venous Blood Gas (VBG) as a Surrogate for ABG Analysis.......................... Step 1: Authentication of Data...................................................................................... Step 2: Characterization of the Acid-Base Disturbance ............................................... Step 3: Calculation of the Expected Compensation...................................................... The Alpha-Numeric (a-1) Mnemonic ........................................................................... The Metabolic Track ..................................................................................................... The Respiratory Track .................................................................................................. Step 4: The ‘Bottom Line’: Clinical Correlation .......................................................... 11.8.1 Clinical Conditions Associated with Simple Acid-Base Disorders ................ 11.8.2 Mixed Disorders .............................................................................................. Acid-Base Maps ............................................................................................................
254 254 255 256 257 258 259 260 261 262 263 265
11
A. Hasan, Handbook of Blood Gas/Acid-Base Interpretation, DOI 10.1007/978-1-4471-4315-4_11, © Springer-Verlag London 2013
253
254
11.1
11
The Analysis of Blood Gases
Normal Values Mixed Venous
Peripheral Venous
95−100 mmHg (PaO2)
38−42 mmHg
40 mmHg
>95 %
>70 %
65−75 %
36−44 mmHg
44−46 mmHg
42−50 mmHg
Arterial
Partial Pressure of O2 Saturation Partial Pressure of CO2 Oxygen Content
~20 ml
~15 ml
~15 ml
O2/100 ml blood pH
7.36−7.44
H+
37−43 nEq/L
HCO3–
22−26 mEq/L
7.32−7.36
7.32−7.38 42−48 nEq/L
24−30 mEq/L
23−27 mEq/L
11.1.1 Venous Blood Gas (VBG) as a Surrogate for ABG Analysis Under some circumstances, such as in ICUs or emergency rooms, it may be convenient to sample venous blood gases (VBGs). Peripheral blood gases can be sampled by standard venipuncture; central venous blood gases through central venous catheters; and mixed venous blood gases through the distal port of a pulmonary artery catheter (PAC). The latter are convenient to assess in a patient who has already had a PAC inserted. Central and mixed venous gases more closely reflect arterial gas measurements than do peripheral venous gases. Venous pH, PvCO2, and HCO3− are used to follow trends in the arterial pH, PaCO2 and HCO3− respectively, provided there is no hemodynamic instability. PvO2 does not mirror PaO2 in view of the fact that O2 extraction by tissues occurs upstream to the venous sampling point.
11 Malatesha G, Singh NK, Bharija A, et al. Comparison of arterial and venous pH, bicarbonate, PCO2 and PO2 in initial emergency department assessment. Emerg Med J. 2007;24:569. Malinos
Data Loading...
