Lab 2 - Isohydria: Acid-base balance, gasometry Flashcards
(143 cards)
1
Q
What can acid-base disturbances signifficantly impact?
A
case morbidity and mortality
2
Q
What is isohydria
A
The concentration of H+ ions in the blood
PH= -log10 H+
3
Q
What is the stability of isohydria essential for
A
Cell membranes and enzyme activity
4
Q
What can a change in PH result in
A
electrolyte imbalance,
change in muscle irritability too
5
Q
Why is intracellular and extracellular buffers importaint
A
If the rate of H+ production is too rapid for elimination for the body
6
Q
What is the function of the buffer solution
A
It can resist PH changes
7
Q
What is the most importaint physicochemical buffer system in all fluid compartments?
A
Carbonic acid - bicarbonate system
8
Q
Besides Carbonic acid - bicarbonate system, what are the other systems
A
Primary - Seccondary phosphate system
Protein-Proteinate buffer system
9
Q
What form the vital buffer system
A
Lungs and kindey
10
Q
How does the lung regulate the PH acticity
A
by retaining or excreeting CO2
11
Q
What happens with the equation in the lung when the `H+ is increased
A
Equation moves to the left generating extra CO2
Leading to hypercapnia stimulating the ventilation and lungs can eliminate the CO2
12
Q
The capacity to retain CO2 is limited
True or False
A
True
Because of oxygen demand
13
Q
Pulmonary capacity to excrete CO2 is low
A
False
The Pulmonary capacity to excrete CO2 is it’s HUGE
14
Q
What is Kussmaul breathing
A
Normal frequency, but very deep inspiration and expiration
15
Q
The kidneys can excrete or retain CO2
True or false
A
False
The kidney can excrete or retain H+
and also regenerate HCO3- via Complex tubular mechanism
16
Q
How does the kidney regenerate HCO3-
A
via Complex tubular mechanism
17
Q
How long does it take for the complex tubular mechanism to regenerate HCO3-
A
Long time
Hours to days
18
Q
If the CO2 levels in the body increase, what happens with the EQUATION due to kidney buffer system
A
The equation will push to the RIGHT
- Produce excess H+ and HCO3- and then H+ can be eliminated by the KIDNEY
19
Q
Acid-Base evaluation is a routine test in emergency patients. True or false
A
True
20
Q
What can the acid-base status tell us something about
A
Function of the VITAL BUFFER SYSTEMS
21
Q
The acid-base analyzers are simple test not complex
true or false
A
False
They are complex devices
22
Q
What does the acid-base analyzers measure
A
blood-gas parameters electrolytes hemoglobin haemaocrit lactate glucose etc
23
Q
Venous blood is essential for assessment of the RESPIRATORY function
True or false
A
False
Arterial blood is ssential for assesment of the respiratory function
24
Q
Both arterial and venous sample provide usefull information about the metabolic state on the animal
True or false
A
True
25
You must avoid air contamination of the samples
| True or false
True
26
Astrup-technique is a CO2 retaining method
False
| Its a method to prevent air contamination of the sample
27
What will be present in aircontaminated samples
Increased pO2
| Note 150 mmHg pO2 in athmospheric air
28
CO2 will evaporate into the air shortly after sampling, the pCO2 may be DECREASED
True or false
True
29
When sampling anticoagulated blood should be used
| True or false
True
| Ca-equilibrated Li-Heparanized syringe
30
In case of longer storage of sample the pCO2 will be increased
True or false
True
31
How long can you store the sample in room temperature
No more than 5-10min
32
How long can you store the sample in the refrigerator (0-4 degree)
Not more than 30min
33
How do you measure PH and CO2
By Analyzers utilze ion selective electrodes (ISE)
34
At which temp are the samples analysed under?
37 degrees
35
The soluibility of gasses are dependent on temseratuse
| True or false
True
36
The measured values need to be corrected to the temperature of the patient
True or false
True
37
Actual PH in blood
Ph 7,35-7,45
38
Partial pressure
| pCO2
Respiratory Parameter
40mmHg
(35-45)
39
Standard Bicarbonate concentration
| HCO3- mmol/L
Metabolic Parameter
21-24 mmol/L
Bicarbonate conc of plasma, if the blood is equlibrated to 40mmHg pCO2 on 37 degrees its value depends on pCO2
40
Actual Base excess (ABE) (demand) or residue (mmol/L)
Metabolic Parameter
+-3,5 mmol/L
Titratable acidity or basicity - the amount of acid or base needed to equlibrate blood to PH 7,4 (pCO2 is stabilized at 40 mmHg/l on 37 degrees)
41
TCO2
| Total CO2 concentration in plasma (mmol/L)
23-30 mmol/L
| CO2 content of blood liberated by strong acid.
42
TCO2 is 10% higher than plasma HCO3-
| True or false
False
| TCO2 is 5% higher than plasma HCO3-
43
TCO2 gives no direct information about respiratory function.
| True or false
True
| TCO2 gives no direct information about respiratory function.
44
TCO2 may be ignored when HCO3- result is pressent
| True or false
True
45
PH in blood during acidosis
<7,4
46
PH in blood during alkalosis
>7,4
47
At which PH value is the Acidaemia decompensated
At PH <7,35,the Acidaemia is decompensated
48
At which PH value is Alkalaemia decompensated
At PH >7,45, the Alkalaemia is decompensated
49
What is step one in Acid-Base state analysis
Evaluate wheter Acidaemia (acidosis) or Alkalaemia (Alkalosis) is present
50
What is the blood PH referece range
Between 7,35-7,45
51
What does compensated/decompensated mean
Indications of the outcome, the effectiveness of all processes together - regardless of whether or not we see compensatory effort
52
Step 1 in evaluation of ABB state must not be omitted(excluded) because the shift of the other parameters are compared to the PH change
True or false
True
53
What is step 2 in AB state investigations
Search for the Cause = PRIMARY PROCESS of the alteration of the observed PH alteration
54
Acidaemia and alkalemia can occur due to metabolic or respiratory changes
True or false
True
55
Predominant change of pCO2 reffers primarly to
Respiratory proceses
56
Predominant change of HCO3- and ABE refers primarly to
Metabolic processes
57
Respiratory background
In case of pCO2 show a strong shift in the opposite direction as PH
True or False
False
| In case of pCO2 show a strong shift in the same direction as PH
58
Respiratory background
| What happens when pCO2 is >40mmHg
More of it binds to water and forms carbonic acid
59
Respiratory background
| Increased pCO2 can be called a shift in alkaloid direction
False
| Increased pCO2 result in acidic direction
60
Respiratory background
| In situations of impared gass exhange, the ramaining high CO2 forms? and lead to?
Carbonic acid
| Shifts PH to acidosis = RESPIRATORY ACIDOSIS
61
Respiratory background
| When does respiratory alkaloisis happen? Exsample
When hyperventilation is pressent - to mutch CO2 is exhaled = causes elevation of the PH = RESPIRATORY ALKALOISIS
62
Metabolic background
When the PH alteration is caused by a metabolic process or kidney malfunction
63
Metabolic background
| Metabolic parameters is
HCO3- and ABE
64
Metabolic background
| In case of Lactic acid production what will occur
Metabolic acidosis
| Both metabolic parameters are shifted to acidic direction
65
Metabolic background
| What is actual base excess
It is a calculated parameter which has a defined aid correction of acid base disturbances
In alkalosis - Parameter shifts from 0 to positive range= in the lack of acids.
66
Negative base excess means
a lack of base
67
Always evaluate wheter the change (resp and metab) parameter respond to ...........
The alteration of PH
68
The primary process is the one that leads to the acid-base disturbance = This parameter is always shifted in the SAME direction as the PH and usually this shift is significant
True or false
True
69
When can you detect compensatory effects
When the shift switches in the oposite direction compared to PH
70
If all parameters shift in the same direction as the PH
Primary process shows signifficantly bigger shift
71
What i s characterized as a bigger shift
25-30% more than normal value
72
What is mixed acidosis
All parameters shifted in same direction as PH - mostly seen in advance acidosis
73
What is step 3 in AB state evaluation
Evaluate wheter compensation effort is visuable in the result or not
74
If either respiratory or metabolic parameters is shifted in the opposite direction than the PH - what will happen
Compensatory effect is visuable
75
What happens due to Compensatory effect in metabolic acidosis in the lung
Lungs try to compensate by highly effective gas exchange
= Very deep breath and longer gas exchange
= Kussmaul breathing
= excretion of lots of CO2 - PH is acidic and CO2 changes in alkaline direction
76
What is step 4 in AB state evaluation
Give an example what can cause the established changes
77
Metabolic acidaemia/Acidosis
PH
HCO3-
BE
<7,4
| <20mml/L
78
Metabolic acidaemia/Acidosis
| Causes
1. HCO3- loss:
| 2. Increased acid intake:
79
Metabolic acidaemia/Acidosis
| Causes of HCO3 loss
diarrhoea
Ileus
kidney tubular disturbances
80
Metabolic acidaemia/Acidosis
| Causes of Increased acid intake:
Increased acid intake:
- Fruits
- too acidic silage
- overdose of acidifying drugs (ammonium chloride, vit C)
- Increased acid production - lactic acid prod due to anaerobic glycolysis, frequent in anorectic, weak animals
- In cattle - grain overdose, leading to volatile acid production.
- Increased ketogenesis, leading to ketosis due to relative or objective starvation or DIABETES MELLITUS
- Decreased acid excretion: RENAL FAILURE
- Ion exchange: HYPER KALAEMIA (H/K PUMP)
- Some Xenobiotic- ethylene-glycol toxicosis:
Metabolites are acidic molecules leading to metabolic acidosis and finally remal failure will worsen it
81
What are the effects of Metabolic acidaemia/Acidosis
1. Kussmaul breathing = hyperventilation (not panting)
2. Hypercalcaemia - increased mobilation from bones in case of long term acidosis.
3. Vomiting, depression
4. Hyperkalaemia: decreased cardiac muscle activity.
SA, AV block, Bradycardia
5. in urine- titrable acidity increases(not process of renal origin)
82
Treatment of Metabolic acidaemia/Acidosis
Providing adequate ventilation
If PH <7,2 = Infusion therapy involving alkaline fluid
(amount is calculated by using ABE)
83
Treatment of Metabolic acidaemia/Acidosis
| ABE formula
Required amount of base (mmol) = ABE*Bwt*K
K is a coeffesient
K in small animals: 0,3
K in large animals: 0,2
Half of amount given first
1-2 hours control = is the other half nessessary
84
Treatment of Metabolic acidaemia/Acidosis
ABE formula - Half of the calculated amount shold be given first
True or false
True
85
What is the anion gap
The anion gap is a usefull parameter when attempting to determine the cause of metabolic acidaemia
86
The anion gap describes the difference between the....
Commonly measured cations in plasma, and the commonly measured anions
87
How do you maintain the electronneutrallity
By keeing the concentration of cations and anions equal in the plasma
88
Unmeasured cations (UC+) include
1. Proteins that are positively charged + at physiologic ph
| 2. Free or ionized forms of calcium (Ca2+) and magnesium (Mg2+) (Not seen in high concentration)
89
Unmeasuref anions (UA-) include
1. Proteins that are negatively charged - at physiologic ph (Albumin mostly)
2. Acids that are produced during physiologic and pathologic processes. (Lactate, Phosphates, Sulphates and ketones)
3. Some toxins and drugs: Methanol, salicylate, ethylene glycol.
90
UA- are found in lower concentration and are therefore hasn't got a great impact on the anion gap
True or false
False
They are found in higer concentration and has a greater impact on the anion gap.
91
What is the reference range for anion gap
8-16mmol/L
92
Why is the anion gap usefull for us to determine
Because its useful to determine wheter metabolic acidaemia is due to primary HCO3- loss or accumulation of organic acids
93
To maintain electronneutrality, how do youbalance a decrease in HCO3-
By an increase of Cl- or UA-. If CL- replaces the HCO3- it usually happen due to direct HCO3- loss (eg. Diarrhoea), the anion gap will be normal.
= Hyperchloraemic metabolic acidose
94
What happens if the reduction of HCO3- is due to accumulation of UA- (lactate, bhb)
The Cl- stays normal
| = Normochloraemic metabolic acidosis.
95
Name cases of NORMAL ANION GAP
| HYPERCHLORAEMIC
1. Diarrhoea (HCO3- loss)
2. Early kidney failure
(H+ retention, decreased ammonia excretion)
3. Renal tubular acidosis
(Proximal (FANCONI SYNDROME) or distal tubular effect)
4. Acidifying substances (NH4Cl)
96
Name cases of INCREASED ANION GAP
| NORMOCHLORAEMIC
1. Azotaemia or uraemia
( Advanced kidney failure - organic acid accumulation)
2. Lactacidosis
(Shock, hypovolaemia, poor tissue perfusion, tissue necrosis)
3. Ketoacidosis
( Diabetic ketoacidosis - increased hepatic production of ketone bodies)
4. Toxicosis
(Ethylene gycol toxicosis - also alcohol)
97
Metabolic alkalemia/ alkalosis
PH
HCO3-
BE
PH >7,4
HCO3- >28mmol/l
BE >+3,5mmol//L
98
Metabolic alkalemia/ alkalosis
| Causes
1. Increased allkaline intake
= Overdose of bicarbonate, or feeding rotten food
2. Increased ruminal alkaline production
= High protein intake, Low carbohydrate intake, anorexa, hypomotility
3. Decreased hepatic ammonia catabolism (liver failure)
4. Increased acid loss
= vomiting, gastric dilation volvulus syndrome, abomasal displacement
5. Ion exchange
= hypokalemia - due to henle loop diuretics remember H+/K+ pump.
(Paradoxical aciduria)
99
Metabolic alkalemia/ alkalosis
| Effects
1. Breathing depression (compensory resp. acidosis)
- low breathing rate - hypoventilation
2. Muscle weakness - hypokalemia
3. Hypocalcaemia due to increased Ca2+ bindings of ALBUMIN
4. Ammonia toxicosis
5. Arryhtmia, biphasic P, QT increase (AV conduction disorder), Flat T, U wave
6. Paradoxical aciduria
100
Metabolic alkalemia/ alkalosis
| Treatment
In general its enough to treat the underlying electrolyte imbalance
101
Respiratory acidaemia/acidosis
PH
pCO2
PO2
```
PH = <7,4
pCO2 = 40 mmHg
pO2 = <40mmHg
```
102
Respiratory acidaemia/acidosis
| Causes
1. Upper airway obstruction
2. Pleural cavity disease, PNEUMOTHORAX
3. Pulmonary disease: SEVERE PNEUMONIA, PULMONARY OEDEMA, DIFFUSE LUNG METASTASIS, PULMONARY THROMBOEMBOLISM
4. Depression of central control of respiration
DRUGS, TOXINS, BRAINSTEM DISEASE
5. Neuromuscular depression of respiratory muscles
6. Muscle weakness, eg. muscle weakness in hypokalemia
7. Cardiopulmonary arrest
103
Respiratory acidaemia/acidosis
| Effects
1. DYSPNOEA
2. CYANOSIS
3. SUFFOCATION
4. MUSCLE WEAKNES
5. TIREDNESS
104
Respiratory acidaemia/acidosis
| Treatment
1. Assisting the ventilation - providing fresh air or oxygen therapy
2. Treatment of the cause - eg
- DIURETIC treatment in case of fluid accumulation in the lung, PULMONARY OEDEMA,
- Specific cardiologic treatment, in case of underlying cardiac diseases
- Treatment of pneumonia= removal of fluid from plural space etc.
105
Respiratory acidaemia/acidosis
Treatment
Mildly anxiolytic/sedationg drugs to decrease the fear and excitement of animals caused by hypoxia
True or false
True
106
Respiratory alkalaemia/alkalosis
PH
pCO2
PO2
PH >7,4
pCO2 < 40 mmHg
pO2 > 40 mmHg
107
Respiratory alkalaemia/alkalosis
| Causes
1. Increased loss of CO2 = HYPERVENTILATION
- Excitation
- Forced ventilation (anaesthesia)
- Epileptiforme seizures
- Fever, hyperthermia
- Intertitial lung disease
108
Respiratory alkalaemia/alkalosis
| Effects
1. Hyperoxia, the decreased pCO2 : pO2 ratio may lead to APNOEA
2. Increased elimination of HCO3- by the KIDNEYS
109
Respiratory alkalaemia/alkalosis
| Treatment
1. Anxiolytic or mild sedative drug in case of HYPEREXCITATION
It is important to increase the pCO2 level by closing the nose or nostrils until breathing normalises (only few min)
110
Blood gas analysis is performed to .........
Assess effectiveness of gas exchange
| = Ventilation in the lung during anaesthesia or dyspnoea
111
Sample and sampling for Blood Gas analysis
| Where to take samples from
Arterial blood because it's essential for PRECICE assessment of respiratory FUNCTION
= How effective the gas exchange is in the alveoli
112
What does venous blood gas analysis reflect
How mutch oxygen that is consumed by the body
113
It is not necessary to use antigoagulated blood when performing blood gas analysis
True or False
FALSE
We use anticoagulated blood
Ca-equilibrated Li-heparinised plasma, preheparinized syringe
114
Which sampling method shall be used when performing blood gas analysis
The Astrup-technique
| - Closed sampling method
115
Why must the blood gas sample be stored with no air/vacum space
Because CO2 can evaporate
| Air contamination causes false increased pO2 pressure
116
How long can you store the sample before measuring
Within 15min or place on ice to minimize changes in blood gas PARTIAL PRESSURE as a result of continuous metabolism
117
The blood gas analyses....
Directly the pCO2 and pO2 with the iron spesific electrodes (ISE)
118
In which condition are the samples investigated under
Standarized temp 37 degrees
119
The dissociation of gasses is independent of temp
| True or false
False
| Both standard 37 degrees and the patient temp has to be accounted for
120
Parameters and refferance ranges
| pO2 - Partial pressure of oxygen
Indicates the ability of the lung to oxygenate blood
Arterial= 88-118 mmHg
Venous= 35-45 mmHg
121
Parameters and refferance ranges
| pCO2 - Partial pressure of carbon dioxide
Indicates the ability of the alveolar gas exchange to remove the CO2.
It is directly proportional to the rate of CO2 production, and inversely proportional to alveolar ventilation
Arterial = 35-45 mmHg
Venous = 35-45 mmHg
122
Parameters and refferance ranges
Oxygen saturation
SAT or SatO2
```
Oxygen saturation (%)= Calculated from Hb and pO2
Indicates the fraction of oxygen-saturated hemoglobin relative to total hemoglobin in the blood
Arterial= 90-100%
Venous= 70-80%
```
123
Parameters and refferance ranges
FiO2
Fraction of inspired oxygen
Is the assumed % of O2 concentration participating in gas exchange in the alveoli
Room air= 0,209 = 20.9%
O2 enriched= 0,21-1,0
>0,5 risk of O2 toxicity
124
What is the most importaint parameter to access the gas exchange capacity in animals
paO2 and paCO2
125
Overall effectiveness of gass exchange are catherorized into 3 groups
```
Normventilation
- Arterial= 80-110 mmHg in room air
-
Hypoventilation <60 mmHG
Hyperventilation - for CO2 hypocapnia or hypercapnia are used
```
126
Oxygen saturation value in room air
97-100%
127
Partial oxygen pressure under 40-50 mmHg - what could be visuable
Cyanosis
128
Hypoventilation
| pCO2
>45 mmHg (most reliable in arterial blood)
129
Hypoventilation
Hypoxemia depends on the degree of hypercapnea, and the FiO2
True or false
True
130
Hypoventilation
| Low O2 saturation depends on
Blood Hb concentration, RBC cound
131
Hypoventilation
pCO2
Hypoxemia
Low O2 saturation
132
Hypoventilation causes
1. Upper airway obstruction
2. pleural effusion
3. drugs or disorders affecting central control of respiration = general anesthesia
4. Neuromuscular diseases (reacts on muscle and respiratory system, eg. HYPOKALAEMIA)
5. Overcompensation of metabolic alkalosis
133
Hypoventilation Effects
Dyspnoea
| Cyanosis
134
Hypoventilation treatment
1. Assisting ventilation eg. assisted breathing, oxygen treatment
2. Diurethic treatment - incase of fluid accumulation in lungs, pulmonary oedema> or in the thoracic cavity
3. Mildly anxiolytic/ sedating treatment
135
Additional to hypoventilation, arterial blood gas tensions are also influenced by
Ventilation perfusion missmatch (VA/Q)
136
Ventilation perfusion missmatch
1. Normal ventilation
2. Inadequate ventilation
1. Normal ventilation with inadequate perfusion
blood passes alveoli for oxygen= EMBIOLA, HEART INSUFFIENCY
2. Inadequate ventilation with normal perfusion
ventilation of alveoli doesn't allow enough oxygen
137
Hyperventilation
| PaCO2
<35 mmHg
138
Hyperventilation
Hyperoxaemia is usually present together with decreased SAT
True or false
False
Hyperoxaemia is usually present together with INcreased SAT
139
Hyperventilation
| Causes
1. Iatrogen
= Forced ventilation during anesthesia (high FiO2)
2. Seizures, epilepsy
3. Excitation
(mild=frequently visiting vet. Extreme= shock after accident)
4. Compensation of severe metabolic acidosis
= Kussmaul breathing
140
Hyperventilation
Venous samples should not be used to assess directly gas exchange
True or false
True
141
Hyperventilation
| What does oxygen saturation inform us about
It informs about tissue O2 usage
142
Hyperventilation
| When does ISCHEMIC reaction occur
Venous saturation below 60% indicates that the body is in lack of oxygen
143
IMPORTAINT
| acid-base or blood gas analyzers regardless which name we use include......
1. ISE for pH, CO2, HCO3-
2. Ions: Ca2+, Na+, K+, Cl-
WHen we interpret, all 3 barameters should be considered
- ACID BASE PARAMETER
- BLOOD GAS ANALYSIS
- INOGRAM
