ISMAIL M. SIALA. Acid-base disorders Pulse Hemoglobin Blood Pressure Temperature Ca, K, …...
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Transcript of ISMAIL M. SIALA. Acid-base disorders Pulse Hemoglobin Blood Pressure Temperature Ca, K, …...
ISMAIL M. SIALA
ACID-BASE DISORDERS
Acid-base disorders
Pulse
Haemoglobin
Ca, K, …Temperatur
e
Hydrogen Ion Concentratio
n
Blood Pressure
AbnormalCellularFunction
Acid-base disorders
Pulse
Hemoglobin
Blood Pressure
Tem
perat
ure
ProperCell
Function
Ca, K, …
Physiological
Daily Metabolism
Pathological
DKA
Hydrogen Ion Concentration
Acid-base disorders
Hydrogen Ion Concentration
H+H+
AcidosisAlkalosis
Compensatory Mechanisms
H+ should be normal for normal cellular function.
The body will try to restore the H+ to normal
Compensatory Mechanisms
Complete
H+ returns to normal range
Incomplete
H+ approaches normal range but still abnormal
Compensatory Mechanisms
Kidney
Lung
• CO2-HCO3 System• Hydroxyapatite-Bone• Haemoglobin
Body Buffers
CO2-bicarbonate system
H+ + HCO3 H2CO3 H2O + CO2
Kidney
Lung
pH and H+ concentration
The blood pH represents the H+ concentration pH = - log10 aH+ aH+ = 10 (-pH) )
where aH+ is activity of H+
H+ (nM) 44 40 36
pH 7.36 7.47.44
AlkalosisAcidosis
Acid-base disorders
Hydrogen Ion Concentration
H+H+
AcidosisAlkalosis
pHpH
PH 7.36-7.44 7.4 +.04
PaCO2 35 – 45 mmHg 40 + 5
HCO3 21 – 28 mmol\l 25 +3
PaO2 83 – 108 mmHg
Acid base disturbances
Arterial blood sample Normal values
Heparinized syringe
Radial artery
• A 2 ml syringe• Heparinized• Radial/ femoral artery• Draw 1 ml of blood• Send for analysis
immediately or send in an ice pack
Acid-base disorders
AcidosisAlkalosis
Acid-base disorders
AcidosisMetabolicRespiratory
AlkalosisMetabolicRespiratory
HCO3
Metabolic acidosis
a pH< 7.36 characterized by low plasma HCO3-.
PaCO2 will secondary to
hyperventilation .
Definition:
ACID PaCO2
ALKALI HCO3
H+ + HCO3 H2CO3 H2O + CO2
Mechanisms of Excess H+ in metabolic acidosis
H+ +HCO3 HCO3
Loss of HCO3 more production of H+
Kidney GIT
Small intestine Pancreas
H+ + HCO3 H2CO3 H2O + CO2
H+ + HCO3 H2CO3 H2O + CO2
Anion Gap
ANION GAP
Na+
Anion Gap
HCO3_
Cl-
“Anion gap represents the difference between readily measured anions and cations”
Anion gap = Plasma Na+ - (Cl- + HCO3-)
N= 8 – 14 mmol\l
Unmeasured Anions: albumin, phosphate, sulphate, lactate, ketoacids, others.
Unmeasured Cations: calcium, Mg, globulins, K.
Aetiology of metabolic acidosis
Na+
Anion GapHCO3
_
Cl-
Na+
Anion GapHCO3
_
Cl-
Increased Anion gap acidosis:Lactic acidosisKetoacidosis Diabetic
AlcoholToxins Methanol
Ethylene glycolSalicylate
Uraemia ARF CRF
Normal Anion gap acidosisHyperchloremic acidosis
GIT HCO3- lossDiarrheaPancreatic drainage
Renal tubular acidosisDrugs CA inhibitors
Anion Gap
Metabolic acidosis
Features of primary disease
• Kussmaul’s Breathing• Altered consciousness• Hypotension
Features of Metabolic Acidosis
Clinical Features:
Metabolic acidosis
For primary disease
• Arterial Blood Gas analysis.
For Metaboli
c Acidosis
Investigations:
Arterial blood gas findings
METABOLIC ACIDOSIS
pH
N
PaCO2
/N
HCO3
Compensated
Treatment of Metabolic Acidosis
Treat the underlying cause Correct Acidosis
Correct fluid & electrolyte disturbances
Oral HCO3 replacement in GI loss or RTA .
parentral Na HCO3 in severe acidosis pH <7.1
CO
2
RESPIRATORY ACIDOSIS
Definition:a pH < 7.36 due to retention
of CO2 as a result of alveolar ventilation ACID
PaCO2
ALKALI HCO3
H+ + HCO3 H2CO3 H2O + CO2
Respiratory Physiology
RC
RN
Ms
Ribs
Pl S
Lu
Br
Air
InspirationACTIVE
ExpirationPASSIVE
Acute Chronic
Airway Obstruction
• Foreign body• Laryngospasm• Severe bronchospasm
• COAD
Respiratory Center Depression
• Morphine overdose• CVA• Trauma -
Neuromuscular
• High cervical cord resection
• Myasthenia gravis• Gullian Barre syndrome• Organophosphorus
• MS• Muscular dystrophies• Motor neuron
disease• Diaphragmatic
paralysis
Restriction of chest movements
• Tension Pneumothorax• Flail chest
• Kyphoscolisis• Ankylosing spodylitis
-• Primary alveolar
hypoventilation-Obesity
Aetiology (CO2 Retention)
Respiratory acidosis
Features of primary disease
• CO2 Retention:• Throbbing Headache • Altered level of consciousness(severe)• Myoclonus &hyperreflexia• Astrexis, Flapping tremors• Central cyanosis • Collapsing pulse• Warm periphery• Papilloedema
Features of Respiratory Acidosis
Clinical Features:
Respiratory acidosis
For primary disease
• Arterial Blood Gas analysis.
For Respiratory Acidosis
Investigations:
Arterial blood gas findings
RESPIRATORY ACIDOSIS
pH
N
PaCO2
HCO3
N/
Compensated
Respiratory failure
Type I respiratory
failure
PaO2 < 60 mmHg
N/ PaCO2
Type II respiratory
failure
PaCO2 >50 mmHg
Hypoxia with any value of PaO2
Treatment of Respiratroy Acidosis
Treat the underlying cause Correct CO2 Retention
Naloxone if Narcotic overdose is suspected
Low oxygen concentration
Mechanical ventilation in severe cases
HC
O3
METABOLIC ALKALOSIS
Definition:a pH > 7.44 characterized
by high plasma HCO3
PaCO2 may .In normal renal function it
is rare, why?
ACID PaCO2
ALKALI HCO3
H+ + HCO3 H2CO3 H2O + CO2
Aetiology
• GIT loss• Vomiting• Aspiration of gastric contents
Loss of H+, Cl, & Na (Associated with EC volume depletion)
• Diuretics• penicillinsLoss through kidney
K depletion
• Cushing• OthersMineralocorticoid excess
• In patients with impaired renal functionExogenous alkali
Metabolic Alkalosis
Features of primary disease
• Tetany:• Acute Fall in Ionized Calcium level.
• Manifest:• Carpo-pedal Spasm.• Laryngeal spasm.
• Latent:
• Aletered level of consciousness
Features of Alkalosis
Clinical Features:
Chvostok sign Traussau sign
Metabolic Alkalosis
For primary disease
• Arterial Blood Gas analysis.
For Metaboli
c Alkalosis
Investigations:
Arterial blood gas findings
METABOLIC ALKALOSIS
pH
N
PaCO2
N/
HCO3
Compensated
Treatment of Metabolic Alkalosis
Treat the underlying cause
Mineralo corticoid excess
Hypokalaemia
Improve GFR
Correct EC fluid depletion GFR enhance HCO3 excretion.
CO
2
RESPIRATORY ALKALOSIS
Definition: pH>7.44 due to CO2
washout as a result of hyperventilation
ACID PaCO2
ALKALI HCO3
H+ + HCO3 H2CO3 H2O + CO2
Aetiology
Hypoxia Voluntary CNS Disease
CVA Infections Trauma Tumours
DrugsAspirin Hepatic Failure Gram Negative Septicaemia Heat Exposure Mechanical overventilation
Respiratory Alkalosis
Features of primary disease
• Tetany:• Acute Fall in Ionized Calcium level.
• Manifest:• Parasthesia, numbness around mouth• Carpo-pedal Spasm.• Laryngeal spasm.
• Latent:
• Aletered level of consciousness
Features of Alkalosis
Clinical Features:
Chvostok sign Traussau sign
Respiratory Alkalosis
For primary disease
• Arterial Blood Gas analysis.
For Respiratory Alkalosis
Investigations:
Arterial blood gas findings
RESPIRATORY ALKALOSIS
pH
N
PaCO2
HCO3
/N
Compensated
Treatment of Respiratory Alkalosis
Treat the underlying cause Supportive measures
Rebreathing in a paper bag in Hyperventilation syndrome + sedation
pH PaCO2 HCO3
METABOLIC ACIDOSIS
(OR LOW
NORMAL)
Compensatory
METABOLIC
ALKALOSIS
(OR HIGH NORMAL)
Compensatory
RESPIRATORY ACIDOSIS
(OR LOW
NORMAL)
Compensatory
RESPIRATORY ALKALOSIS
(OR HIGH
NORMAL)
Compensatory
Summary