MMSC407 Exam 3 Acids and Bases

what is the purpose of blood gases?

management of respiratory and metabolic disorders

pCO2 and the lungs are apart of what system?

respiratory system

HCO3- and the kidneys represent what?

Metabolic

what is the reference range for partial pressure of CO2 gas?

35-45 mmHg (Arterial)

what is the reference range for partial pressure of O2 gas?

83-100 mmHg (Arterial)

what is the reference range for total CO2 gas?

22-29 mmol/L

dissolved CO2 formula

pCO2 (.0306)

H2CO3 =

dissolved CO2

Total CO2 = ______ + _______

H2CO3 + HCO3

blood buffer reference value

46-49 mEq/L

what blood buffer is the largest percentage?

hemoglobin (80%)

The concentration of titratable base when titrating the blood or plasma with a strong acid or base to a plasma pH of 7.40 at a pCO2 of __ mmHg at 37C

40

what is the reference value for the base excess?

+2.5 mmol/L

what is the reference value for the base deficit?

-2.5 mmol/L

used to estimate the amount of sodium bicarbonate to be given to correct pH problems

.1 (Base Excess) (PT weight Kg)

-log H+

pH

reference value for pH

7.35-7.45

Calculate the pH of a solution which contains 4 X10^-8 mmol/L of hydrogen ion

-logH+ (4 X10^-8)

-log10^-8 - log 4

8-.6

pH= 7.4

What is the pH of a solution with the

following hydrogen ion concentration?

H+ = 0.0000001

-log10^-7 - log1

7-0

pH=7

The in vivo blood pH is influenced by the plasma bicarbonate and dissolved ____ ___ levels

carbonic acid

pk + log HCO3 (metabolic) + H2CO3 (respiratory) =

pH

what arteries do you want to use for blood collection samples?

radial

brachial

what anticoagulant do you want to use for blood collection?

heparin

what are the drawing complications of the Allen test?

thrombosis

hemorrhage

Exposure of Arterial Blood Sample toAtmospheric Air will cause:

pH

pCO2

pO2

pO2 values over ____ will lose pO2

pH increases

pCO2 decreases

pO2 increases

pO2 values over 158 mmHg will lose pO2

Specimens not processed immediately willcause (due to glycolysis):

pH

pCO2

pO2

pH decreases

pCO2 increases

pO2 decreases

Syringe not properly capped

Bubbles

Clots

Venous Blood collected instead of arterial

other blood collection problems

Physiologic pH range of Blood "Compatible" with Life

6.8-7.8

Pre analytical Errors for accurate pH measurements

Potentiometry

The measurement of the electric potential (voltage) difference between two electrode sin an electrochemical cell

Potentiometry

This reference electrode produces a constant reference potential to which the indicator electrode potential can be compared. (244 mv)

Calomel Reference Electrode

Saturated KCL

This solution completes the circuit between the blood sample and both the reference and indicator electrodes

salt bridge

A glass membrane, specific for pH due toi ts mineral content, measures the electrical potential at its surface due to the hydrogen ion activity

indicator electrode

Mineral Content for pH

Hydrogen Sensitive Glass:

SiO2

Na2O

CaO

SiO2: 72.2%

Na2O: 21.4%

CaO: 6.4%

Mineral Content for pH

Sodium Sensitive Glass:

SiO2

Na2O

Al2O3

SiO2: 71%

Na2O: 11%

Al2O3: 18%

Known buffers are used to ____ the pH portion of blood gas analyzer

calibrate

what are the two pH's for calibration?

7.384 and 6.840

bromide contamination

protein build up on pH glass surface

scratched pH glass surface

incorrect pH buffers

sources of error

what is the reference value for blood pCO2 arterial?

35-45 mmHg

what is the reference value for blood pCO2 venous?

38-50 mmHg

Blood pCO2 is the ____ component of acid base balance

It is regulated by the ___

respiratory

lungs

hypercapnia definition

what is it caused by?

increased CO2 caused by hypoventilation

what does hypercapnia cause?

respiratory acidosis

during hypercapnia, pCO2 is

> 50 mm Hg

Hypoventilation: a decrease in alveolar ventilation causes a rate of gas exchange across the respiratory membrane. This is depended on what?

surface area and thickness of respiratory membrane

solubility of gas

difference in PP

What is emphysema? (COPD)

loss of lung elasticity

alveoli destroyed

what decreases with emphysema?

surface area and gas exchange

emphysema causes what?

SOB

fluid accumulation leading to a barrier against gas diffusion

bronchopneumonia

swollen or inflamed bronchi

gas exchange is reduced

asthma

what regulates respiration?

medulla of the brain

what do receptors measure?

O2, CO2, pH levels in blood and CSF

Signals are sent to the medulla, which controls what?

rate and depth of respiration

what two condition depress the control center?

barbiturates

cerebral injury

examples of decreased mechanical / neuromuscular control of breathing

mechanical obstruction

asphyxiation

myasthenia gravis

crushed chest

muscle weakness due to decrease in acetyl choline

myasthenia gravis

congestive heart failure leads to less blood to lungs. This is an example of...

decreased cardiac output

what is the treatment for hypoventilation?

ventilate

hypocapnia definition and what is it caused by?

decreased CO2

caused by hyperventilation

what does hypocapnia cause?

respiratory alkalosis

hypocapnia pCO2 value

less than 35 mmHg

hyperventilation is caused by

hypoxemia

high altitude

salicylate poisoning

temp/ fever

hysteria / anxiety

below normal level of O2 in the blood, specifically in arteries

hypoxemia

hypocapnia Tx

breath in own CO2

pCO2 is measured by an ___ in _ activity at the pH sensitive glass electrode

increase in H+

H+ increases as pH...

decreases

(Barometric Pressure - Water Vapor Pressure) X % pCO2gas=

pCO2 (mmHg)

What would the 10.00% pCO2 gas be in mmHg under the same barometric conditions?

pCO2 mmHg = 713 mmHg X 0.10

pCO2 = 71.3 mmHg with a 10% Calibration gas

what are the sources of error in the calibration of the pCO2 electrode?

membrane

temp

calibration

what is the reference value for arterial blood pO2?

83-108 mmHg

does blood pO2 increase or decrease with age and high altitudes?

decrease

what is the reference value for venous blood pO2?

< 40 mmHg

what is the treatment for increased pO2 values?

enriched O2 (can be toxic)

what can retrolental fibroplasia contribute to (infants)?

glaucoma

retinal detachment

For adults, Pure Oxygen at normal atmospheric pressure for over 4 days can cause ___, ____, and decreased pulmonary function

pain

cough

hypoxia

lack of O2

(below 40 mmHg)

what leads to hypoxia?

high altitudes from decreased diffusion capacity of alveolar membrane

decreased diffusion capacity of alveolar membrane can lead to what conditions?

respiratory distress syndorme

Hypoxia is a complication in what type of infants (L/S ratio)

premature

high altitudes (hypoxia) can lead to a decrease in alveolar ventilation. This can lead to what?

emphysema

asthma

bronchopneumonia

hypoxia can lead to a decrease in mechanical / neuromuscular control of breathing. What four conditions can this lead to?

mechanical obstruction

asphyxiation

myasthenia gravis

crushed chest

hypoxia can lead to decreased cardiac output, leading to...

congestive heart failure

what type of accidents require arterial pO2 measurements?

cerebrovascular accidents (brain stem injury)

lung disorders, drug overdose, newborns, acute myocardial infarction is from what type of accident?

cerebrovascular accidents (brain stem injury)

Polarography is used to measure...

pO2

Supplying a constant voltage to an electrode and monitoring the current change (amps) as oxygen is reduced at the cathode

polarography

The electrode measures the rate of current flow which is proportional to the oxygen tension of the sample

polarograhy

what is used to calibrate the pO2 electrode?

gases

A ratio, expressed as a percentage of the volume of oxygen bound to Hemoglobin

pO2 saturation

what is the reference value for pO2 saturation?

95-98%

The pO2 saturation helps to predict the amount of ___ available for tissue ____.

O2

perfusion

measures concentrations of oxygenated hemoglobin (oxyHb), deoxygenated hemoglobin (deoxyHb or reduced Hb), carboxyhemoglobin (COHb), and methemoglobin (MetHb) as a percentage of the total hemoglobin concentration in the blood sample.

Co-oximetry

is Co-oximetry measured directly?

yes

Sample is aspirated into the Co-oximeter and is ____ with lysing reagent to release hemoglobin

lysed

what is measured with the co-oximeter?

absorbance at different wavelengths

Total Hemoglobin (tHb) =

O2Hb + HHb + COHb + MetHb

total amount of O2 that Hgb can carry

Oxygen content of Hgb

____ mL of Oxygen per gram of Hemoglobin

1.34

oxygen dissociation curve: Left Shift

decrease temp, 2 3DPG, H+

higher affinity

increase pH

oxygen dissociation curve: Right shift

increase temp, 2 3 DPG, H+

reduced affinity

decrease in pH