ANATOMY AND PHYSIOLOGY OF REPRODUCTIVE SYSTEM.pptx
Acid base disorders
1. Acid Base DisordersAcid Base Disorders
A Practical ApproachA Practical Approach
Ass. Lecturer critical care medicineAss. Lecturer critical care medicine
Cairo University HospitalCairo University Hospital
WALID KAMEL, MBChWALID KAMEL, MBCh
2. Regulation of acid-base balance:Regulation of acid-base balance:
Defense against the change in pH…
because H+ react highly with cellular
proteins resulting in alteration in their function.
Avoiding acidemia and alkalemia by tightly
regulation H+
is essential for normal cellular
function.
3. What information does ABG provide about the patient?What information does ABG provide about the patient?
ABG provide an assessment of the following:
1)PaO2
: Amount of o dissolved in the blood, it give initial
information on efficiency of oxygenation.
2)PaCO2
: Adequacy of ventilation is inversely proportional to
Paco2
(when ventilation increase PaCO2
decrease
and vice verse).
3) Acid base status (pH, HCO3
, base deficit, anion gap).
4) Hb, Hct, oxygen saturation.
5) Electrolyte e.g. Na+
, K+
.
4. Diagnosis of acid Base disordersDiagnosis of acid Base disorders
•Arterial blood sample is common utilized clinically
but venous blood may be useful in determining acid
base status. (Except in CHF and shock).
•Blood sample should be in heparin coated syringe.
•The sample should be analyzed as soon as possible.
•Air bubble should be eliminated.
•The syringe should be capped and placed in ice.
5. Acid Base -Basic ConceptsAcid Base -Basic Concepts
Hydrogen IonHydrogen Ion [H[H++
]]is tightly controlledis tightly controlled
[H[H++
]]is determined by the balance betweenis determined by the balance between
PaCOPaCO22 and serumand serum HCOHCO33 (bicarbonate)(bicarbonate)
Henderson-Hasselbalch EquationHenderson-Hasselbalch Equation
[H[H++
] = 24 (PaCO] = 24 (PaCO22 / HCO/ HCO33
--
))
11. Acid-Base AnalysisAcid-Base Analysis
What do You Need?What do You Need?
Arterial Blood gases (pH, COArterial Blood gases (pH, CO22))
Serum chemistry (Na, K, Cl, HCOSerum chemistry (Na, K, Cl, HCO33))
12. A 39 year old woman was admitted with a history ofA 39 year old woman was admitted with a history of
generalized weakness, dyspnea, continuous nauseageneralized weakness, dyspnea, continuous nausea
and diarrhea. Bowel motions were frequent andand diarrhea. Bowel motions were frequent and
watery.watery.
ABG: pH 7.29, PaCO2 25.6, PaO2 98ABG: pH 7.29, PaCO2 25.6, PaO2 98
NaNa++
=125, K=125, K++
=2.8, Cl=2.8, Cl--
=101, HCO=101, HCO33=14=14
Study CaseStudy Case
MetabolicMetabolic Acidosis
13. Simple Vs. MixedSimple Vs. Mixed
Compensation ConceptCompensation Concept
[H[H++
] = 24 (PaCO] = 24 (PaCO22 / HCO/ HCO33
--
))
Is compensation appropriate?Is compensation appropriate?
Must know “rules of thumb” of compensationMust know “rules of thumb” of compensation
18. Case Study - 1Case Study - 1
A 39 year old woman was admitted with a history of generalizedA 39 year old woman was admitted with a history of generalized
weakness, dyspnea, continuous nausea and diarrhea. Bowelweakness, dyspnea, continuous nausea and diarrhea. Bowel
motions were frequent and watery.motions were frequent and watery.
ABG: pH 7.29, PaCO2 25.6, PaO2 98ABG: pH 7.29, PaCO2 25.6, PaO2 98
NaNa++
=125, K=125, K++
=2.8, Cl=2.8, Cl--
=101, HCO=101, HCO33=12=12
PaCO2 = [1.5 x HCO3 + 8] ± 2PaCO2 = [1.5 x HCO3 + 8] ± 2
PaCo2=[1.5X12]+8 ± 2PaCo2=[1.5X12]+8 ± 2
PaCO2 =PaCO2 = 2525 ± 2± 2
Simple (compensated) metabolic acidosis
19. Metabolic AcidosisMetabolic Acidosis
Anion GapAnion Gap
Metabolic acidosis is groupedMetabolic acidosis is grouped
according to the anion gapaccording to the anion gap
Anion Gap (AG)Anion Gap (AG)
The difference between measured cationsThe difference between measured cations
and measured anions in the serumand measured anions in the serum
AG= NaAG= Na++
- [Cl- [Cl--
+ HCO+ HCO33
--
]]
Normal (9 - 12 mEq/LNormal (9 - 12 mEq/L))
22. Non anion gap metabolic acidosis:
Metabolic acidosis associated with normal AG is
typically characterized by hyperchloremia.
Calculation of AG in urine:
Urine AG = ( Na+
+ K+
) – CL-
In a patient with a hyperchloraemic metabolic
acidosis:
•A negative UAG GIT loss of bicarbonate (eg
diarrhoea)
•A positive UAG impaired renal distal acidification
(ie renal tubular acidosis).
23. BASE EXCESSBASE EXCESS
It is an estimate of the amount of strong acid orIt is an estimate of the amount of strong acid or
base needed to correct the met. component of anbase needed to correct the met. component of an
acid base disorder (restore plasma pH to 7.40at aacid base disorder (restore plasma pH to 7.40at a
PacoPaco22 40 mmHg)40 mmHg) represent only the metabolic
component of acid base disorders.
Its +ve value indicate metabolic alkalosis, wIts +ve value indicate metabolic alkalosis, while
–ve value indicate metabolic acidosis.
24. Study Case - 1Study Case - 1
A 39 year old woman was admitted with a history ofA 39 year old woman was admitted with a history of
generalized weakness, dyspnea, continuous nauseageneralized weakness, dyspnea, continuous nausea
and diarrhea. Bowel motions were frequent andand diarrhea. Bowel motions were frequent and
watery.watery.
ABG: pH 7.29, PaCO2 25.6, PaO2 98ABG: pH 7.29, PaCO2 25.6, PaO2 98
NaNa++
=125, K=125, K++
=2.8, Cl=2.8, Cl--
=101, HCO=101, HCO33=14=14
AG = Na – (Cl+HCO3)
AG = 125 – (101+14) = 10
Normal anion gap metabolic acidosis
25. Metabolic AlkalosisMetabolic Alkalosis
Characterized byCharacterized by
PrimaryPrimary ↑↑ in HCO3 concentrationin HCO3 concentration
CompensatoryCompensatory ↑↑ in PaCO2in PaCO2
Classified according to urinary chlorideClassified according to urinary chloride
Chloride responsiveChloride responsive
Chloride resistantChloride resistant
28. Case Study - 2Case Study - 2
A 78 year old lady presented with at a 1 weekA 78 year old lady presented with at a 1 week
history of abdominal pain and vomiting.history of abdominal pain and vomiting.
ABG: pH 7.49, PaCO2 52, PaO2 78ABG: pH 7.49, PaCO2 52, PaO2 78
Na 137, K 2.2, CL 91, HCO3 38Na 137, K 2.2, CL 91, HCO3 38
Urine CI 43Urine CI 43 mEq/LmEq/L
Metabolic Alkalosis
Vomiting and hypokalemia
30. Rule 1Rule 1
Validate the ABGValidate the ABG
[H[H++
] = 24 (PaCO] = 24 (PaCO22 / HCO/ HCO33
--
))
80 - [H80 - [H++
]] ~ the last two digits of the pH~ the last two digits of the pH
[H[H++
] of 24: pH of (80-24=56) ~ 7.] of 24: pH of (80-24=56) ~ 7.5656
[H[H++
] of 53: pH of (80-53=27) ~ 7.] of 53: pH of (80-53=27) ~ 7.2727
31. Another method
Determine if numbers fit:Determine if numbers fit:
H+ =H+ =
3
2
HCO
PCO24×
H+ = (7.8-PH)×100.H+ = (7.8-PH)×100.
The Rt side of the equation should beThe Rt side of the equation should be
within 10% of the Lt Side. If not so anotherwithin 10% of the Lt Side. If not so another
ABG or chemistry panel for HCO3 should beABG or chemistry panel for HCO3 should be
done.done.
32. Rule 2Rule 2
What is the pH?What is the pH?
> 7.40 → 1° disorder is alkalosis> 7.40 → 1° disorder is alkalosis
< 7.40 → 1° disorder is acidosis< 7.40 → 1° disorder is acidosis
Does theDoes the PaCOPaCO22 explains the pH?explains the pH?
YesYes → 1° disorder is respiratory→ 1° disorder is respiratory
No → 1° disorder is metabolicNo → 1° disorder is metabolic
33. Rule 3Rule 3
Does theDoes the PaCOPaCO22 explains the pH?explains the pH?
YesYes → 1° disorder is respiratory→ 1° disorder is respiratory
No → 1° disorder is metabolicNo → 1° disorder is metabolic
34. Rule 4Rule 4
Apply compensation rulesApply compensation rules
If calculated compensation:If calculated compensation:
Within the expected range → simpleWithin the expected range → simple
acid/base disorderacid/base disorder
Less or more than expected → 2°Less or more than expected → 2°
acid/base disorderacid/base disorder
35. There is no over correction orThere is no over correction or
compensation in acid base balance →compensation in acid base balance →
if the compensatory response is moreif the compensatory response is more
or less than expected → it is mixedor less than expected → it is mixed
acid base disorderacid base disorder
36. Case Study - 1Case Study - 1
A 39 year old woman was admitted with a historyA 39 year old woman was admitted with a history
of generalized weakness, dyspnea, continuousof generalized weakness, dyspnea, continuous
nausea and diarrhea. Bowel motions were frequentnausea and diarrhea. Bowel motions were frequent
and watery.and watery.
ABG: pH 7.29, PaCO2 26, PaO2 98ABG: pH 7.29, PaCO2 26, PaO2 98
NaNa++
=125, K=125, K++
=2.8, Cl=2.8, Cl--
=101, HCO=101, HCO33=12=12
PaCO2 = [1.5 x HCO3 + 8] ± 2PaCO2 = [1.5 x HCO3 + 8] ± 2
PaCO2 = 25 ± 2PaCO2 = 25 ± 2
Simple (compensated) metabolic acidosis
37. Case Study - 2Case Study - 2
A 78 year old lady presented with at least aA 78 year old lady presented with at least a
week history of abdominal pain and vomiting.week history of abdominal pain and vomiting.
ABG: pH 7.49, PaCO2 52, PaO2 78ABG: pH 7.49, PaCO2 52, PaO2 78
Na 137, K 2.2, CL 91, HCO3 38Na 137, K 2.2, CL 91, HCO3 38
Urine CI 43Urine CI 43 mEq/LmEq/L
Metabolic Alkalosis
∆∆PaCO2 = 0.9 ∆ HCO3 : 0.9 X 14 = 17PaCO2 = 0.9 ∆ HCO3 : 0.9 X 14 = 17
PaCO2 = 53PaCO2 = 53
Simple
38. Mixed Acid-Base DisordersMixed Acid-Base Disorders
pH may be within normal (7.35-7.45)pH may be within normal (7.35-7.45)
Cannot over-compensateCannot over-compensate
Simultaneous co-existence ofSimultaneous co-existence of
disordersdisorders
2 respiratory + 2 metabolic2 respiratory + 2 metabolic
Acute on top of chronicAcute on top of chronic
The pH determines which is primary:The pH determines which is primary:
pH < 7.40 – primary disorder is AcidosispH < 7.40 – primary disorder is Acidosis
pH > 7.40 – primary disorder is AlkalosispH > 7.40 – primary disorder is Alkalosis
39. A 21 year old MS is brought to the ER at ~3A 21 year old MS is brought to the ER at ~3
am, stuporous and tachypneic. History isam, stuporous and tachypneic. History is
remarkable for failing the respiratory moduleremarkable for failing the respiratory module
in 2in 2ndnd
year. An ABG and electrolytes haveyear. An ABG and electrolytes have
been drawn by the ER nurse.been drawn by the ER nurse.
ABG: pH=7.38, PaCOABG: pH=7.38, PaCO22=18=18
NaNa++
=140, K=140, K++
=3.8, Cl=3.8, Cl--
=106, HCO=106, HCO33=12=12
Case Study - 3Case Study - 3
40. A 21 year old MS is brought to the ER at ~3 am, stuporous and tachypneic.A 21 year old MS is brought to the ER at ~3 am, stuporous and tachypneic.
History is remarkable for failing the respiratory module in 2History is remarkable for failing the respiratory module in 2ndnd
year. An ABG andyear. An ABG and
electrolytes have been drawn by the ER nurse.electrolytes have been drawn by the ER nurse.
ABG: pH=7.38, PaCOABG: pH=7.38, PaCO22=18=18
NaNa++
=143, K=143, K++
=3.8, Cl=3.8, Cl--
=106, HCO=106, HCO33=12=12
Case Study - 3Case Study - 3
AG = 143-106-12 = 25
Wide AG Metabolic acidosis
PaCO2 = 1.5 X 12 +8 = 26 ±2
Wide AG metabolic acidosis and Respiratory Alkalosis
Aspirin
Overdose
42. A 55 year old woman presented to the ERA 55 year old woman presented to the ER
with dyspnea and wheezes. She is heavywith dyspnea and wheezes. She is heavy
smoker. An ABG and electrolytes have beensmoker. An ABG and electrolytes have been
drawn by the ER nurse.drawn by the ER nurse.
ABG: pH=7.33, PaCOABG: pH=7.33, PaCO22=65=65
NaNa++
=144, K=144, K++
=4.2, Cl=4.2, Cl--
=104, HCO=104, HCO33=32=32
Case Study - 4Case Study - 4
43. A 55 year old woman presented to the ER with dyspnea andA 55 year old woman presented to the ER with dyspnea and
wheezes. She is heavy smoker. An ABG and electrolytes havewheezes. She is heavy smoker. An ABG and electrolytes have
been drawn by the ER nurse.been drawn by the ER nurse.
ABG: pH=7.33, PaCOABG: pH=7.33, PaCO22=65=65
NaNa++
=144, K=144, K++
=4.2, Cl=4.2, Cl--
=104, HCO=104, HCO33=32=32
Case Study - 4Case Study - 4
Chronic Respiratory Acidosis
44. Approach To ALL Acid/BaseApproach To ALL Acid/Base
ProblemsProblems
Don’t get overwhelmed by all the numbersDon’t get overwhelmed by all the numbers
at once!at once!
Use a methodical system to dissect theUse a methodical system to dissect the
numbers.numbers.
Don’t jump ahead when doing calculations.Don’t jump ahead when doing calculations.
45. METHODICAL SYSTEMMETHODICAL SYSTEM
Get all your numbers in front you first…Get all your numbers in front you first…
Look at pH first: Acidotic or alkalotic?Look at pH first: Acidotic or alkalotic?
Metabolic or Respiratory?Metabolic or Respiratory?
Go straight to Bicarb!Go straight to Bicarb!
Correlate bicarb with PCO2 and it should beCorrelate bicarb with PCO2 and it should be
obviousobvious
Calculate anion gap no matter what theCalculate anion gap no matter what the
disturbance is!disturbance is!
46. SYSTEM…continuedSYSTEM…continued
After you come up with “primary disturbance”,After you come up with “primary disturbance”,
your next question should ALWAYS BE =your next question should ALWAYS BE =
““Is there compensation?”Is there compensation?”
For metabolic acidosis… do last two digits of pHFor metabolic acidosis… do last two digits of pH
equal PCO2 or notequal PCO2 or not
For resp acidosis… is it acute or chronic, and isFor resp acidosis… is it acute or chronic, and is
the HCO3 up appropriately?the HCO3 up appropriately?
For resp alkalosis… is it acute or chronic, and isFor resp alkalosis… is it acute or chronic, and is
the HCO3 down appropriately?the HCO3 down appropriately?
47. CompensationCompensation
The Two Given Rules of Compensation:The Two Given Rules of Compensation:
1.1. METABOLIC = BICARB (HCO3)METABOLIC = BICARB (HCO3)
……So if you dealing with figuring out yourSo if you dealing with figuring out your
disturbance and it is metabolic (up or downdisturbance and it is metabolic (up or down
HCO3), then the compensation will beHCO3), then the compensation will be
RESPIRATORY (is the PCO2 appropriatelyRESPIRATORY (is the PCO2 appropriately
up or down)up or down)
48. Compensation…continuedCompensation…continued
2.2. RESPIRATORY = PCO2RESPIRATORY = PCO2
……So if you are dealing with respiratorySo if you are dealing with respiratory
alkalosis or acidosis, you want to know ifalkalosis or acidosis, you want to know if
the METABOLIC (HCO3) compensationthe METABOLIC (HCO3) compensation
is appropriate or notis appropriate or not
49. SYSTEM…continuedSYSTEM…continued
If the compensation is INAPPROPRIATE, thenIf the compensation is INAPPROPRIATE, then
you automatically have a SECONDyou automatically have a SECOND
superimposed acid/base disordersuperimposed acid/base disorder
50. Case 1Case 1
A 75-year-old man presents to the ED after aA 75-year-old man presents to the ED after a
witnessed out of hospital VF cardiac arrest.witnessed out of hospital VF cardiac arrest.
Arrived after 10 minutes, CPR had not beenArrived after 10 minutes, CPR had not been
attempted.attempted.
The paramedics had successfully restoredThe paramedics had successfully restored
spontaneous circulation after 6 shocks.spontaneous circulation after 6 shocks.
On arrival the man is comatose with a GCS of 3On arrival the man is comatose with a GCS of 3
and his lungs are being ventilated with 50%and his lungs are being ventilated with 50%
oxygen via ET tube.oxygen via ET tube.
He has HR of 120/min and a blood pressure ofHe has HR of 120/min and a blood pressure of
150/95 mmHg.150/95 mmHg.
52. Case 2Case 2
A 65-year-old man with severe COPDA 65-year-old man with severe COPD
has just collapsed in the respiratoryhas just collapsed in the respiratory
high-care unit.high-care unit.
On initial assessment he is found to beOn initial assessment he is found to be
apnoeic but has an easily palpableapnoeic but has an easily palpable
carotid pulse at 90/min.carotid pulse at 90/min.
A nurse is ventilating his lungs withA nurse is ventilating his lungs with
an Ambu bag and supplementary O2an Ambu bag and supplementary O2
54. Case 3Case 3
A 75-year-old lady is admitted to the EDA 75-year-old lady is admitted to the ED
following a VF cardiac arrest, which wasfollowing a VF cardiac arrest, which was
witnessed by the paramedics.witnessed by the paramedics.
A spontaneous circulation was restoredA spontaneous circulation was restored
after 4 shocks, but the patient remainedafter 4 shocks, but the patient remained
comatose and apnoeic.comatose and apnoeic.
The paramedics intubated her trachea,The paramedics intubated her trachea,
and on arrival in hospital her lungs areand on arrival in hospital her lungs are
being ventilated with an automaticbeing ventilated with an automatic
ventilator using a tidal volume of 900 mlventilator using a tidal volume of 900 ml
and a rate of 18 breaths/min.and a rate of 18 breaths/min.
56. Case 4Case 4
An 18-year-old male insulin dependentAn 18-year-old male insulin dependent
diabetic is admitted to the ED.diabetic is admitted to the ED.
He has been vomiting for 48 hours andHe has been vomiting for 48 hours and
because he was unable to eat, he omittedbecause he was unable to eat, he omitted
his insulin.his insulin.
He has HR of 130/min and his bloodHe has HR of 130/min and his blood
pressure is 90/65 mmHg.pressure is 90/65 mmHg.
He is breathing spontaneously with deepHe is breathing spontaneously with deep
breaths at a rate of 35/min. His GCS is 12breaths at a rate of 35/min. His GCS is 12
(E3, M5, V4(E3, M5, V4).).