Saturday, July 19, 2014

The Analysis of Blood Gas



Blood gas analysis (BGA) is also known as arterial blood gas determination (ABG), and is considered a special test in the clinical laboratory. The commonly assayed parameters are partial pressure carbon dioxide (pCO2), hydrogen ion concentration (pH) and bicarbonate (HCO3). The determination of these substances helps in the evaluation of the acid-base status of a patient.

Image credit: Lara Enriquez


The following are certain precautions observed by medical technologists in the extraction of arterial blood for blood gas analysis.

1. The best specimen is arterial blood.

This is because arterial blood is more homogenous than venous blood. The blood could be collected in the following common arterial sites: the radial artery, the brachial artery, the femoral artery and the scalp artery.

The most ideal anticoagulant is dry heparin, and the preferable syringe is a glass syringe. Recently, new receptacles are manufactured which are specifically for BGA.

2. Collect the specimen anaerobically (without air).

Your specimen should be covered at all times to prevent the escape of carbon dioxide to the air. It should be transported immediately to the testing laboratory. If it is left uncovered, unreliable results will be obtained which will lead to a wrong diagnosis by the Clinician/physician.

3. Preserve in crushed ice, if not tested immediately.

The low temperature has to be maintained. An increase in temperature would cause the gas to evaporate. It must also be preserved properly to obtain reliable results, aside from making sure that it is covered.

The body naturally maintains a state of balance called homeostasis. In the case of blood pH, this is done by the lungs and the kidneys which act as compensatory organs for one another. When the lungs are dysfunctional just like in respiratory diseases (emphysema, TB, chronic bronchitis, etc), the kidneys respond by excreting or retaining bicarbonate (HCO3).

On the other hand, when the kidneys are dysfunctional, the lung will respond by the increase retention or excretion of carbon dioxide (CO2). Through these physiologic processes, the critical pH (acidity and alkalinity) of blood is maintained at 7.35 to 7.45. Any slight variation from this pH, whether an increase or decrease, will lead to coma and eventually death. It is therefore imperative that the body maintains this slightly alkaline pH of blood for good health.

The following are acid-base conditions and the corresponding compensatory mechanisms :

Values : pH - decreased , PCO2 normal, HCO3 - decreased

Condition - metabolic acidosis

Compensatory mechanism - hyperventilation , increase excretion of CO2

decreased retention of CO2

Values: pH increased, HCO3 - increased , PCO2-normal

Condition - metabolic alkalosis

Compensatory mechanism - hypoventilation, decreased excretion of CO2

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increased retention of CO2

Values : pH- increased , PCO2 - decreased , HCO3 -normal

Condition - respiratory alkalosis

Compensatory mechanism : increased retention of HCO3

decreased excretion of H+

Values: pH-decreased , PCO2 -increased, HCO3 -normal

Condition: respiratory acidosis

Compensatory mechanism : increased retention of HCO3,

increased excretion of H+

Clinical laboratory scientists or medical technologists solve for the pH of blood making use of the

Henderson-Hasselbalch Equation: (H & H equation). The formula for this is:

pH = 6.1 + log (HCO3)/DCO2

HCO = TCO2-DCO2

DCO2 = PCO2 X 0.031

Where: pH =indicates the acidity or alkalinity of a solution (hydrogen ion concentration.

HCO3 - bicarbonate

DCO2 - dissolved carbon dioxide

TCO2 - total carbon dioxide

Normal values are:

pH = 7.35-7.45

HCO3 = 22 - 26 mmol/L

PCO2 = 35 - 35 mmHg

TCO2 = 23-27 mmol/L

Arterial blood gas has very important clinical significances. It is crucial that the Medical Technologists know the precautions and perform the determination accurately. A well performed ABG signifies a patient well served.




This was published by http://voices.yahoo.com/the-analysis-blood-gas-2482704.html?cat=5.

Reference:

Calbreath, Donald F. Fundamentals of Clinical Chemistry

Wednesday, May 21, 2014

CLINICAL CHEMISTRY 3 FINAL EXAMS - TABLE OF SPECIFICATIONS



CLINICAL CHEMISTRY 3 FINAL EXAMS  - TABLE OF SPECIFICATIONS

TOPIC
PERCENT (%)
ITEMS





ENDOCRINOLOGY
48
55

TOXICOLOGY
31
35

DRUG TESTING
21
25

TOTAL
100%
115
Grand Total= 130 items
TRANSCRIPTION

15


TRANSCRIPTION = 15 POINTS FOR A GRAND TOTAL OF 130.

Please Bring:
Calculator (no borrowing of calculators)
Blue book ( 1 pc.)
Permits
Pencil lead 2 (2 pcs) for SCANTRON answer sheet

Type of test

1. MULTIPLE CHOICE (115 pts), which includes:
Matching type (3 pts.)
      Problem solving (3 pts)
      Case analysis (7 pts.)

II. TRANSCRIPTION (15 pts.)

Wednesday, April 30, 2014

TABLE OF SPECIFICATIONS - CLINICAL CHEMISTRY 3- LECTURE



CLINICAL CHEMISTRY 3- LECTURE 

MIDTERM EXAMS,  SUMMER AY: 2013-2014

TABLE OF SPECIFICATIONS

TOPIC
 (%)
MC
MT
PS
CA
ID
TRANS
TOTAL ITEMS
ENDOCRINOLOGY
72
25
24
5
20
7
9
90
TOXICOLOGY
28
10
6
10

3
6
35









TOTAL

100%
35
30
15
20
10
15
125
GRAND TOTAL

LEGEND:

ID- IDENTIFICATION
MC – MULTIPLE CHOICE
MT- MATCHING TYPE
PS – PROBLEM SOLVING
CA - CASE ANALYSIS
TRANS - TRANSCRIPTION

WHAT TO BRING:

1.       BLACK OR BLUE BALLPENS (2)
2.       BLUEBOOK #1
3.       CALCULATORS (BORROWING OF CALCULATORS IS NOT ALLOWED)
4.       PERMITS

PLEASE COME IN COMPLETE UNIFORM.

FYI
/VBG

Sunday, April 20, 2014

Winners of Edublogging CC3 2012-2013



The prizes are not much because we do not have donors. Kaya lollipop na lang. Claim your prizes tomorrow from me at the ground floor, room of Sir Nino. Congratulations:

First Prize:

KIMBERLY MIRANDA - CCBLOGNOTES 8d-A - http://kimpressionist.blogspot.com/ 37.16% (123 votes)

Second Prize:

BLESSY CONTRERAS - CCBLOGNOTES 8b-A - http://clinchem8ba.blogspot.com/2013/04/adrenaline-rushsuperhuman.html  23.26% (77 votes)  

Third Prize:

BETINA - CCBLOGNOTES 10-d-C - http://mcbetina17.blogspot.com/  7.55%  (25 votes)  

TO VIEW ACTUAL RESULTS, CLICK HERE.