Date post: | 14-Apr-2018 |
Category: |
Documents |
Upload: | john-ervin-agena |
View: | 223 times |
Download: | 0 times |
of 78
7/30/2019 Celeste_acid Base Slides
1/78
1
7/30/2019 Celeste_acid Base Slides
2/78
Facts and Definitions
1. Acid-base homeostasis - necessary tomaintain life.
2. Acid base balance must be within a definiterange for cellular function to occur.
3. The acidity of a substance, determined bythe hydrogen ion (H+) concentration; is
expressed as pH.
2
7/30/2019 Celeste_acid Base Slides
3/78
pH - measures degree of acidity and
alkalinity
- indicator of H ion concentration
- Normal ph 7.35-7.45
3
7/30/2019 Celeste_acid Base Slides
4/78
4. Acids
a. Release hydrogen ions into solution
b. Have pH < 7
5. Alkalines (bases)
a. Accept hydrogen ions into solutionb. Have pH > 7
4
7/30/2019 Celeste_acid Base Slides
5/78
Acid- substance that can donate or releasehydrogen ions
ie Carbonic acid (H2CO3),Hydrochloric acid
** Carbon dioxide
combines with water toform carbonic acid
5
7/30/2019 Celeste_acid Base Slides
6/78
Base
- substance that can accept hydrogen ions
ie Bicarbonate (HCO3)
6
7/30/2019 Celeste_acid Base Slides
7/78
Body fluids
1. Normally slightly alkaline
2. Normal range is narrow: 7.35 7.45
(pH of 7 is neutral)3. Arterial blood pH < 7.35
is considered acid
4. Arterial blood pH > 7.45is considered alkaline
7
7/30/2019 Celeste_acid Base Slides
8/78
Acids and Bases in the body
1. Body functions constantly produce acids
2. Most acids and bases in the body are weak
3. Acids includea. Carbonic acid, which is eliminated as a gas, carbon
dioxide
b. Lactic, hydrochloric, phosphoric, sulfuric acids,
which are metabolized or excreted as fluids
4. Bicarbonate is the major base
8
7/30/2019 Celeste_acid Base Slides
9/78
Dynamics of Acid Base Balance
Acids and bases are constantly produced in the
body
They must be constantly regulated
CO2 and HCO3 are crucial in the balance
A HCO3:H2CO3 ratio of 20:1 should be
maintained
Respiratory and renal system are active inregulation
9
7/30/2019 Celeste_acid Base Slides
10/78
Body regulation of acid-base balance
Constant response to changes in pH to maintainthe pH in the normal range
3 systems in the body, with various responsetimes, to maintain acid-base balance :
1. Buffers/ Chemical Buffers
2. Respiratory System
3. Renal ( metabolic) System
10
7/30/2019 Celeste_acid Base Slides
11/78
A. Buffer System
1. Responds immediately, but has limited
capacity to maintain
2. Buffers: substances that bind or release
hydrogen ions
a. When body fluid becomes acid, buffers bindwith hydrogen ions to raise pH
b. When body fluid becomes alkaline, buffers
release hydrogen ions to lower pH
11
7/30/2019 Celeste_acid Base Slides
12/78
Buffer systems
a. Bicarbonate-carbonic acid buffer system- blood and interstitial fluid
CO2 + H20 H2C03 H+ + HC03
weak acid weak base
Process is reversible but the ratio of 20 (bicarbonate) to
1 (hydrogen) must be maintained
b. Protein buffer system - intracellular and plasma;
hemoglobin buffer
c. Phosphates buffer system renal tubules
12
7/30/2019 Celeste_acid Base Slides
13/78
B. Respiratory System
- controls CO2 and Carbonic acid content of ECF
1. Responds within minutes2. Includes respiratory center of brain stem and lungs
3. Occurs automatically, not under voluntary control
4. Adjusts the depth and frequency of respiration according to
the pH of the blood; increases or decreases the amount ofcarbon dioxide in the blood; controls the amount ofcarbonic acid formed and adjusts the pH of the blood
a. Hyperventilation: increased depth and frequency ofrespiration; blows off more CO2 in response to an acid pH
b. Hypoventilation: decreased depth and frequency ofrespiration; retains more CO2 in response to an alkaline pH
13
7/30/2019 Celeste_acid Base Slides
14/78
Respiratory System
14
H ions and CO2
(blood)
Stimulates theMedulla Oblongata
RR
Hyperventilation
(blows off CO2) H ions and CO2
(blood)
H ions and CO2
(blood)
Stimulates theMedulla Oblongata
RR
Hypoventilation
(retains CO2)
H ions and CO2(blood)
7/30/2019 Celeste_acid Base Slides
15/78
C. Renal (Metabolic) System
-regulates bicarbonate level in ECF
1. Responds within hours to days
2. Adjusts the amounts of hydrogen and bicarbonate(metabolic component) ions
a. Kidneys excrete H+ ions, or generate and reabsorbbicarbonate ions, in response to an acid pH
b. Kidneys retain H+ ions, or generate and excrete bicarbonate
ions, in response to an alkaline pH
15
7/30/2019 Celeste_acid Base Slides
16/78
How to obtain blood sample?
Allens test - evaluatepatency of radial and ulnarartery
Heparinized syringe and ice-filled container
Pressure dressing, noactivity at the site andcheck 5 ps distal to the siteof punctured artery
Note if patient is under O2
therapy Label the sample and send
immediately to thelaboratory
17
7/30/2019 Celeste_acid Base Slides
17/78
ABG Responsibilities
Arterial blood
Radial or ulnar artery
Allens test
Prepare
Heparinized (Syringe,
specimen container)
Note: 02 therapy Bring specimen to the
LAB (ice)
18
7/30/2019 Celeste_acid Base Slides
18/78
After injection
Maintain extension
position, no activity 8H
Apply pressure 5-15 min
Observe the site
Distal, 5 ps
(Pulselessness, Pain,
Paresthesia,Poikilothermia, Pallor)
Radial artery
30-45 degrees
Brachial artery60 degrees
Femoral artery
90 degrees
19
http://images.google.com.ph/imgres?imgurl=http://www.smithsoem.com/images/pd_arterial_blood_sampling.jpg&imgrefurl=http://www.smithsoem.com/pd_bloodsampling.php&h=368&w=200&sz=11&hl=tl&start=2&tbnid=sd57C6x8uBzdtM:&tbnh=122&tbnw=66&prev=/images%3Fq%3Darterial%2Bblood%2Bgas%26svnum%3D10%26hl%3Dtl%26lr%3D7/30/2019 Celeste_acid Base Slides
19/78
Handling of Specimen
Expel all air bubblesimmediately
Do not agitate the syringe
Discard frothy specimen 1:1000 U/ml HEPARIN
Place sample in ice
Cool sample to 5 C if it can
not be analyzed quickly
20
7/30/2019 Celeste_acid Base Slides
20/78
Determination of Acid-Base Balance: Analysis of
Arterial Blood Gases
pH
PaCO2
HCO3
21
7/30/2019 Celeste_acid Base Slides
21/78
A. pH
1. Normal: 7.35 3.45
2. Acidic: 7.45
22
7/30/2019 Celeste_acid Base Slides
22/78
B. PaCO2
Partial Pressure of carbon dioxide; respiratorycomponent
1. Normal: 35-45 mm Hg
2. Acidic: > 45 mm Hg
(carbon dioxide forms carbonic acid)
Hypercapnia: elevated levels of carbon dioxide inblood
3. Alkaline: < 35 mm HgHypocapnia: decreased levels of carbon dioxide in
blood
23
7/30/2019 Celeste_acid Base Slides
23/78
C. HCO3
Bicarbonate; renal or metabolic component
1. Normal: 22 26 mEq/L2. Acidic: < 22 mEq/L
3. Alkaline: > 26 mEq/L
24
7/30/2019 Celeste_acid Base Slides
24/78
D. Base Excess
1. Calculated value for buffer base capacity: the
amount of acid or base added to blood to
obtain a pH of 7.4
2. Normal: -3 - +3
25
7/30/2019 Celeste_acid Base Slides
25/78
E. PaO2 or pO2
Pressure of oxygen in blood
1. Gives data about level of oxygenation; notused to calculate acid-base status of blood
2. Normal: 80 100 mm Hg
3. Hypoxemia: < 80 mm Hg
26
7/30/2019 Celeste_acid Base Slides
26/78
F. SaO2 oxygen saturation
95% - 100%
27
7/30/2019 Celeste_acid Base Slides
27/78
Interpreting ABG results
1. Check the pH.
2. Determine the PaCO2.
3. Watch the bicarbonate.4. Look for compensation.
5. Determine PaO2 and SaO2.
28
7/30/2019 Celeste_acid Base Slides
28/78
Parameter Normal Value
pH 7.357.45
PaCO2 35
45 mmHgHCO3 22-26 mEq/L
PaO2 80100 mmHg
SaO2 95100 %
29
7/30/2019 Celeste_acid Base Slides
29/78
Interpreting ABG results
1. Check the pH.
pH = 7.35 7.45 (normal)
pH = < 7.35 (acidosis)
pH = > 7.45 (alkalosis)
compensated normal pH
uncompensated abnormal pH
30
7/30/2019 Celeste_acid Base Slides
30/78
Interpreting ABG results
Determine primary cause of disturbance.
Figure out whether the cause is:
Respiratory (PaCO2) or
Metabolic (HCO3)
31
7/30/2019 Celeste_acid Base Slides
31/78
Interpreting ABG results
2. Determine the PaCO2. normal or abnormal
- Respiratory component
Normal: 35-45 mm Hg
a. PaCo2 < 35 mmHg respiratory alkalosis
? pH > 7.45 hypocapnia
a. PaCo2 > 45 mm Hg respiratory acidosis
? pH < 7.35 hypercapnia
32
7/30/2019 Celeste_acid Base Slides
32/78
Interpreting ABG results
3. Watch the bicarbonate.
renal or metabolic component
Normal: 22 26 mEq/L
HCO3 < 22 mEq/L metabolic acidosis
? pH < 7.35
HCO3 > 26 mEq/L metabolic alkalosis
? pH > 7.45
33
7/30/2019 Celeste_acid Base Slides
33/78
Interpreting ABG results
4. Look for compensation: look at the value whichdoes not match the acid base status of thepatients pH:
a. Within normal range: NO compensation
b. Above or below normal AND the pH itself isoutside the normal range: PARTIAL
c. Above or below normal AND the pH is within thenormal range: COMPLETE
34
7/30/2019 Celeste_acid Base Slides
34/78
Interpreting ABG results
5. Determine PaO2 and SaO2
PaO2 80100 mmHg
SaO2 95100 %
- Reflect bodys ability to pick up oxygen from the lungs
Low hypoxemia; can cause hyperventialtion
- Indicate when to make adjustments in theconcentration being administered to the patient
35
7/30/2019 Celeste_acid Base Slides
35/78
Interpreting ABG results Exercises
ACIDIC
dec pH
inc PaCO2 or pCO2
dec HCO3
ALKALINE/ BASIC
inc pH
dec PaCO2 or pCO2
inc HCO3
36
7/30/2019 Celeste_acid Base Slides
36/78
1. pH 7.20 dec acidic
2. pCO2 60 inc acidic
3. HCO3 24 normal normal*
RESPIRATORY ACIDOSIS
no/ absent compensation
37
7/30/2019 Celeste_acid Base Slides
37/78
1. pH 7.20 dec acidic
2. pCO2 60 inc acidic
3. HCO3 30 inc alkaline*
RESPIRATORY ACIDOSISpartial compensation
38
7/30/2019 Celeste_acid Base Slides
38/78
1. pH 7.40* normal acidic*
2. pCO2 48 inc acidic3. HCO3 24 normal normal*
RESPIRATORY ACIDOSISno/ absent compensation
NOTE: If pH is normal but PaCO2 or HCO3 is abnormal,
use 7.4 as a cut off point
7.35 - 7.40 acidosis
7.40 - 7.45 alkalosis
39
7/30/2019 Celeste_acid Base Slides
39/78
1. pH 7.60 inc alkaline
2. pCO2 20 dec alkaline
3. HCO3 18 dec acidic
RESPIRATORY ALKALOSIS
partial compensation
40
7/30/2019 Celeste_acid Base Slides
40/78
1. pH 7.50 inc alkaline
2. pCO2 60 inc acidic
3. HCO3 34 inc alkaline
METABOLIC ALKALOSIS
partial compensation
41
7/30/2019 Celeste_acid Base Slides
41/78
1. pH 7.36* normal acidic
2. pCO2 30 dec alkaline
3. HCO3 20 dec acidic
METABOLIC ACIDOSIS
complete/ full compensation
42
7/30/2019 Celeste_acid Base Slides
42/78
1. pH 7.30 dec acidic
2. pCO2 40 normal normal
3. HCO3 20 dec acidic
METABOLIC ACIDOSIS
no/ absent compensation
43
7/30/2019 Celeste_acid Base Slides
43/78
Acid-Base Imbalance
Classifications
1. Acidosis or alkalosis
a. Acidosis: Hydrogen ion concentration in bloodincreases above normal and pH is below 7.35
b. Alkalosis: Hydrogen ion concentration in blooddecreases below normal and pH is above 7.45
2. Origin of the problema. From the respiratory system
b. From the metabolic system
44
7/30/2019 Celeste_acid Base Slides
44/78
Disorders: Simple or Combined
1. Primary disorders
a. Simple
b. One cause, either respiratory or metabolic
2. Combined disorders
a. More severeb. Both the respiratory and metabolic systems are the
cause of the same imbalance
45
7/30/2019 Celeste_acid Base Slides
45/78
Compensation
1. Only occurs with primary disorders
2. Response by the system not causing the imbalanceto correct the pH
Example: with respiratory acidosis, the kidneys wouldeliminate hydrogen ions in urine to offset the
acidosis caused by hypoventilation of lungs.3. Complete Compensation occurs if the pH is corrected
to the normal range (7.35 7.45)
4. Partial Compensation occurs if there is improvement
in the pH but not to the normal range.5. Compensation can be determined by analysis of the
arterial blood gas results.
46
7/30/2019 Celeste_acid Base Slides
46/78
Treatment
1. Urgency
a. Mental ability and level of consciousness is
often affectedb. Brain function usually affected; brain cells
need proper conditions to perform cellularfunctions
c. Cells cannot function properly if significantacidosis or alkalosis occurs
47
7/30/2019 Celeste_acid Base Slides
47/78
2. Indirect treatment
a. Treating and correcting the precipitating condition
often corrects the acid-base imbalanceb. Directly treating the acid-base imbalance, by
adding or removing hydrogen or bicarbonate ions,
may lead to further imbalances
c. Not usually first line of treatment
48
7/30/2019 Celeste_acid Base Slides
48/78
Types of Acid-Base Imbalances
A. Respiratory Acidosis
pH < 7.35
pCO2 > 45 mm Hg (excess carbon dioxide in the
blood)
Respiratory system impaired and retaining CO2;causing acidosis
49
7/30/2019 Celeste_acid Base Slides
49/78
50
Etiology: pulmonary edema, aspiration,
atelectasis, pneumothorax, sleep apnea
syndrome, pneumonia, asthma,bronchiectasis, overdose of medications
(sedatives, narcotics, anesthetics),
neuromuscular d/o ( Guillain Barre),hypoventilation
s/sx: sudden hypercapnia produces incPR, RR, inc BP, mental cloudinesss,
feeling of fullness in head, papilledema
and dilated conjunctival blood vessels
7/30/2019 Celeste_acid Base Slides
50/78
Respiratory Acidosis
Common Stimuli
a. Acute respiratory failure from airwayobstruction
b. Over-sedation from anesthesia or narcoticsc. Some neuromuscular diseases that affect
ability to use chest muscles
d. Chronic respiratory problems, such as ChronicObstructive Lung Disease
51
7/30/2019 Celeste_acid Base Slides
51/78
Respiratory Acidosis
Signs and Symptoms
a. Compensation: kidneys respond by generating andreabsorbing bicarbonate ions, so HCO3 >26 mm Hg
b. Respiratory: hypoventilation, slow or shallowrespirations
c. Neuro: headache, blurred vision, irritability,confusion
d. Respiratory collapse leads to unconsciousness andcardiovascular collapse
52
7/30/2019 Celeste_acid Base Slides
52/78
Respiratory Acidosis
Collaborative Care
a. Early recognition of respiratory status and treatcause
b. Restore ventilation and gas exchange; CPR forrespiratory failure with oxygen supplementation;intubation and ventilator support if indicated
c. Treatment of respiratory infections with
bronchodilators, antibiotic therapyd. Reverse excess anesthetics and narcotics with
medications such as naloxone (Narcan)
53
7/30/2019 Celeste_acid Base Slides
53/78
Respiratory Acidosis
e. Chronic respiratory conditions
a. Breathe in response to low oxygen levels
b. Adjusted to high carbon dioxide level through metaboliccompensation (therefore, high CO2 not a breathing trigger)
c. Cannot receive high levels of oxygen, or will have notrigger to breathe; will develop carbon dioxide narcosis
d. Treat with no higher than 2 liters O2 per cannula
f. Continue respiratory assessments, monitor further arterialblood gas results
54
7/30/2019 Celeste_acid Base Slides
54/78
Respiratory Acidosis
Nursing Diagnoses
a. Impaired Gas Exchange
b. Ineffective Airway Clearance
55
7/30/2019 Celeste_acid Base Slides
55/78
B. Respiratory Alkalosis
pH > 7.45
pCO2 < 35 mm Hg.
Carbon dioxide deficit, secondary to
hyperventilation
56
7/30/2019 Celeste_acid Base Slides
56/78
57
Etiology: extreme anxiety, hypoxemia,
Fever, hyperventilation, hysteria, hypoxia,
Salicycates (early)
s/sx: lightheadednes, inability to
concentrate, numbness, tingling, loss of
consciousness
7/30/2019 Celeste_acid Base Slides
57/78
Respiratory Alkalosis
Common Stimuli
a. Hyperventilation with anxiety from
uncontrolled fear, pain, stress (e.g. women in
labor, trauma victims)
b. High fever
c. Mechanical ventilation, during anesthesia
58
7/30/2019 Celeste_acid Base Slides
58/78
Respiratory Alkalosis
Signs and Symptoms
a. Compensation: kidneys compensate by eliminatingbicarbonate ions; decrease in bicarbonate HCO3 < 22 mm Hg.
b. Respiratory: hyperventilating: shallow, rapid breathing
c. Neuro: panicked, light-headed, tremors, may develop tetany,numb hands and feet (related to symptoms of hypocalcemia;with elevated pH more Ca ions are bound to serum albuminand less ionized active calcium available for nerve andmuscle conduction)
d. May progress to seizures, loss of consciousness (when normalbreathing pattern returns)
e. Cardiac: palpitations, sensation of chest tightness
59
7/30/2019 Celeste_acid Base Slides
59/78
Respiratory Alkalosis
Collaborative Care
a. Treatment: encourage client to breathe slowly in apaper bag to rebreathe CO2
b. Breathe slowly; breathe with the patient; provideemotional support and reassurance, anti-anxietyagents, sedation
c. On ventilator, adjustment of ventilation settings
(decrease rate and tidal volume)d. Prevention: pre-procedure teaching, preventative
emotional support, monitor blood gases as indicated
60
7/30/2019 Celeste_acid Base Slides
60/78
C. Metabolic Acidosis
pH
7/30/2019 Celeste_acid Base Slides
61/78
62
Etiology: diarrhea, fistulas, diuretics, TPN
w/o Bicarbonate, lactic acidosis, DM,DKA, excessive ingestion of salicylates
(late)- aspirin, high fat diet, malnutrition,
renal insufficiency/ failure
S/sx: headache, confusion, drowsiness,
inc RR, dec BP, cold clammy skin,
dysrythmia, shock
7/30/2019 Celeste_acid Base Slides
62/78
Metabolic Acidosis
Common Stimuli
a. Acute lactic acidosis from tissue hypoxia (lactic acid producedfrom anaerobic metabolism with shock, cardiac arrest)
b. Ketoacidosis (fatty acids are released and converted toketones when fat is used to supply glucose needs as inuncontrolled Type 1 diabetes or starvation)
c. Acute or chronic renal failure (kidneys unable to regulateelectrolytes)
d. Excessive bicarbonate loss (severe diarrhea, intestinal suction,bowel fistulas)
63
7/30/2019 Celeste_acid Base Slides
63/78
Metabolic Acidosis
e. Usually results from some other disease and is
often accompanied by electrolyte and fluid
imbalances
f. Hyperkalemia often occurs as the hydrogenions enter cells to lower the pH displacing the
intracellular potassium; hypercalcemia and
hypomagnesemia may occur
64
7/30/2019 Celeste_acid Base Slides
64/78
7/30/2019 Celeste_acid Base Slides
65/78
Metabolic Acidosis
f. Respiratory: tries to compensate by
hyperventilation: deep and rapid respirations
known as Kussmauls respirations
g. Diagnostic test findings:
1. ABG: pH < 7.35, HCO3 < 22
2. Electrolytes: Serum K+ >5.0 mEq/L
3. Serum Ca+2 > 10.0 mg/dL
4. Serum Mg+2 < 1.6 mg/dL
66
7/30/2019 Celeste_acid Base Slides
66/78
Metabolic Acidosis
Collaborative Carea. Medications: Correcting underlying cause will often improve
acidosis
b. Restore fluid balance, prevent dehydration with IV fluids
c. Correct electrolyte imbalances
d. Administer Sodium Bicarbonate IV, if acidosis is severe anddoes not respond rapidly enough to treatment of primarycause. (Oral bicarbonate is sometimes given to clients withchronic metabolic acidosis) Be careful not to overtreat andput client into alkalosis
e. As acidosis improves, hydrogen ions shift out of cells andpotassium moves intracellularly. Hyperkalemia may becomehypokalemia and potassium replacement will be needed.
67
7/30/2019 Celeste_acid Base Slides
67/78
Metabolic Acidosis
f. Assessment
1. Vital signs
2. Intake and output
3. Neuro, GI, and respiratory status;
4. Cardiac monitoring
5. Reassess repeated arterial blood gases andelectrolytes
68
7/30/2019 Celeste_acid Base Slides
68/78
Metabolic Acidosis
Nursing Diagnoses
a. Decreased Cardiac Output
b. Risk for Excess Fluid Volume
c. Risk for Injury
69
7/30/2019 Celeste_acid Base Slides
69/78
D. Metabolic Alkalosis
pH >7.45
HCO3 > 26 mEq/L
Caused by a bicarbonate excess, due to loss of
acid, or a bicarbonate excess in the body
70
7/30/2019 Celeste_acid Base Slides
70/78
Etiology: excessive vomiting, diuretic,
hyperaldosteronism, hypokalemia, excessive
alkali ingestion, ingestion of excess sodium
bicarbonate/ antacids, massive transfusion ofwhole blood
s/sx: tingling of toes, dizziness, dec RR, inc PR,ventricular disturbances
71
7/30/2019 Celeste_acid Base Slides
71/78
Metabolic Alkalosis
Common Stimuli
a. Loss of hydrogen and chloride ions through
excessive vomiting, gastric suctioning, or
excessive diuretic therapy
b. Response to hypokalemia
c. Excess ingestion of bicarbonate rich antacids
or excessive treatment of acidosis with
Sodium Bicarbonate
72
7/30/2019 Celeste_acid Base Slides
72/78
Metabolic Alkalosis
Signs and Symptoms
a. Compensation: Lungs respond by decreasing the
depth and rate of respiration in effort to retain
carbon dioxide and lower pHb. Neuro: altered mental status, numbness and tingling
around mouth, fingers, toes, dizziness, muscle
spasms (similar to hypocalcemia due to less ionized
calcium levels)
c. Respiratory: shallow, slow breathing
73
7/30/2019 Celeste_acid Base Slides
73/78
Metabolic Alkalosis
d. Diagnostic test findings
1. ABGs: pH> 7.45, HCO3 >26
2. Electrolytes: Serum K+ < 3.5 mEq/L
3. Electrocardiogram: as with hypokalemia
74
7/30/2019 Celeste_acid Base Slides
74/78
Metabolic Alkalosis
Collaborative Care
a. Correcting underlying cause will often improve
alkalosis
b. Restore fluid volume and correct electrolyte
imbalances (usually IV NaCl with KCL).
c. With severe cases, acidifying solution may be
administered.
75
7/30/2019 Celeste_acid Base Slides
75/78
Metabolic Alkalosis
d. Assessment
1. Vital signs
2. Neuro, cardiac, respiratory assessment
3. Repeat arterial blood gases and electrolytes
76
7/30/2019 Celeste_acid Base Slides
76/78
Metabolic Alkalosis
Nursing Diagnoses
a. Impaired Gas Exchange
b. Ineffective Airway Clearance
c. Risk for Injury
77
7/30/2019 Celeste_acid Base Slides
77/78
78
7/30/2019 Celeste_acid Base Slides
78/78