Transcript ALS course slide set - the Australian Resuscitation Council

Arterial Blood Gas Analysis
Learning outcomes
By the end of this session you should understand:
• The normal ranges for arterial blood gas values
• How to use the 5-step approach to arterial blood gas
interpretation
• Some of the common causes of arterial blood gas abnormalities
and what to do to correct them
Venous Blood Gasses
• Significant correlation in pH, PaCO2, PaO2, Bicarbonate, and Base
Excess among ABG and VBG values in healthy individuals
• Caution: in the presence of shock, hypothermia, and hyperthermia,
including during cardiac arrest, there is a poor correlation (in PaO2 in
particular)
• Venous blood gas analysis reveals results rapidly for Electrolytes and
Haemoglobin
VBG normal values (with good perfusion)
PvO2
35 – 40 mmHg on air
pH
7.33 – 7.44
PvCO2
40 – 55 mmHg
HCO3
24 – 28 mmol l-1
BE
+/- 2 mmol l-1
Many slight variations to
normal reference ranges are
given in published literature
5-step approach to
arterial blood gas interpretation
5-step approach to
arterial blood gas interpretation
1. How is the patient?
•
Will provide useful clues to help with interpretation of the results
5-step approach to
arterial blood gas interpretation
1. How is the patient?
•
Will provide useful clues to help with interpretation of the results
2. Assess oxygenation
•
•
•
Is the patient hypoxaemic?
PaO2 > 75 mmHg on air (and increased with higher FiO2)
Aim for normal PaO2
5-step approach to
arterial blood gas interpretation
1. How is the patient?
•
Will provide useful clues to help with interpretation of the results
2. Assess oxygenation
3. Determine the pH (or H+ concentration)
•
Normal pH 7.35 to 7.45
5-step approach to
arterial blood gas interpretation
1. How is the patient?
•
Will provide useful clues to help with interpretation of the results
2. Assess oxygenation
3. Determine the pH (or H+ concentration)
4. Determine the respiratory component
•
Normal PaCO2

35mmHg to 45mmHg
5-step approach to
arterial blood gas interpretation
1. How is the patient?
2. Assess oxygenation
3. Determine the pH (or H+ concentration)
4. Determine the respiratory component
5. Determine the metabolic component
•
•
Normal HCO3  22 mmol l-1 to 26 mmol l-1
Normal base excess  -2 mmol l-1 to +2 mmol l-1
21 year old woman thrown from horse
Initial Information
I:
Paramedics have called
S:
21-year-old woman on the way to hospital has become increasingly drowsy
B:
She has been thrown from her horse at a local event
A:
A Was snoring/threatened - inserted an oropharyngeal airway - improved
B RR 8-10 given oxygen via a face-mask
(FiO2 approximately 40%)
C Pulse 51 - regular, BP 130/60, Capillary refill < 2 seconds, IV inserted and
functioning (bloods taken)
D
AVPU,
Glucose 5.3, no medications given. Dilated left pupil
E Eyes swollen/bruising
R:
Please review urgently and an arterial blood gas sample has been taken
21 year old woman thrown from horse (continued)
Initial Information
I:
Paramedics have called
S:
21-year-old woman on the way to hospital has become increasingly drowsy
B:
She has been thrown from her horse at a local event
A:
A Was snoring/threatened - inserted an oropharyngeal airway - improved
B RR 8-10 given oxygen via a face-mask
(FiO2 approximately 40%)
C Pulse 51 - regular, BP 130/60, Capillary refill < 2 seconds, IV inserted and
functioning (bloods taken)
D
AVPU, Glucose 5.3, no medications given. Dilated left pupil
E Eyes swollen/bruising
R:
Please review urgently and an arterial blood gas sample has been taken
• Step 1: How is the patient?
21 year old woman thrown from horse (continued)
Initial Information
I:
Paramedics have called
S:
21-year-old woman on the way to hospital has become increasingly drowsy
B:
She has been thrown from her horse at a local event
A:
A Was snoring/threatened - inserted an oropharyngeal airway - improved
B RR 8-10 given oxygen via a face-mask
(FiO2 approximately 40%)
C Pulse 51 - regular, BP 130/60, Capillary refill < 2 seconds, IV inserted and
functioning (bloods taken)
D
AVPU, Glucose 5.3, no medications given. Dilated left pupil
E Eyes swollen/bruising
R:
Please review urgently and an arterial blood gas sample has been taken
• Step 1: How is the patient?
-
The reduced level of consciousness will impair oxygenation and ventilation, causing an
increased PaCO2 , a respiratory acidosis
21 year old woman thrown from horse (continued)
Initial Information
I:
Paramedics have called
S:
21-year-old woman on the way to hospital has become increasingly drowsy
B:
She has been thrown from her horse at a local event
A:
A Was snoring/threatened - inserted an oropharyngeal airway - improved
B RR 8-10 given oxygen via a face-mask
(FiO2 approximately 40%)
C Pulse 51 - regular, BP 130/60, Capillary refill < 2 seconds, IV inserted and
functioning (bloods taken)
D
AVPU, Glucose 5.3, no medications given. Dilated left pupil
E Eyes swollen/bruising
R:
Please review urgently and an arterial blood gas sample has been taken
• Step 1: How is the patient?
• There is unlikely to be much compensation (change in bicarbonate)
because of the acuteness of the situation
21 year old woman thrown from horse (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
PaO2
pH
PaCO2
Bicarbonate
Base excess
• What is the next step?
110 mmHg
7.19
78 mmHg
23.6 mmol l-1
-2.4 mmol l-1
40% (FiO2 0.4)
normal values
> 75 mmHg on air
7.35 – 7.45
35 – 45 mmHg
22 – 26 mmol l-1
+/- 2 mmol l-1
21 year old woman thrown from horse (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
PaO2
pH
PaCO2
Bicarbonate
Base excess
110 mmHg
7.19
78 mmHg
23.6 mmol l-1
-2.4 mmol l-1
• What is the next step?
• Step 2: Assess oxygenation
• Is the patient hypoxaemic?
40% (FiO2 0.4)
normal values
> 75 mmHg on air
7.35 – 7.45
35 – 45 mmHg
22 – 26 mmol l-1
+/- 2 mmol l-1
21 year old woman thrown from horse (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
PaO2
pH
PaCO2
Bicarbonate
Base excess
• What is the next step?
110 mmHg
7.19
78 mmHg
23.6 mmol l-1
-2.4 mmol l-1
40% (FiO2 0.4)
normal values
> 75 mmHg on air
7.35 – 7.45
35 – 45 mmHg
22 – 26 mmol l-1
+/- 2 mmol l-1
21 year old woman thrown from horse (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
PaO2
pH
PaCO2
Bicarbonate
Base excess
110 mmHg
7.19
78 mmHg
23.6 mmol l-1
-2.4 mmol l-1
40% (FiO2 0.4)
normal values
> 75 mmHg on air
7.35 – 7.45
35 – 45 mmHg
22 – 26 mmol l-1
+/- 2 mmol l-1
• What is the next step?
• Step 3: Determine the pH (or H+ concentration)
• Is the patient acidaemic; pH < 7.35?
• Is the patient alkalaemic; pH > 7.45?
21 year old woman thrown from horse (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
PaO2
pH
PaCO2
Bicarbonate
Base excess
• What is the next step?
110 mmHg
7.19
78 mmHg
23.6 mmol l-1
-2.4 mmol l-1
40% (FiO2 0.4)
normal values
> 75 mmHg on air
7.35 – 7.45
35 – 45 mmHg
22 – 26 mmol l-1
+/- 2 mmol l-1
21 year old woman thrown from horse (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
PaO2
pH
PaCO2
Bicarbonate
Base excess
110 mmHg
7.19
78 mmHg
23.6 mmol l-1
-2.4 mmol l-1
40% (FiO2 0.4)
normal values
> 75 mmHg on air
7.35 – 7.45
35 – 45 mmHg
22 – 26 mmol l-1
+/- 2 mmol l-1
• What is the next step?
• Step 4: Determine the respiratory component
• If the pH < 7.35, is the PaCO2 > 45 mmHg? – respiratory acidosis
• If the pH > 7.45, is the PaCO2 < 35 mmHg? – respiratory alkalosis
21 year old woman thrown from horse (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
PaO2
pH
PaCO2
Bicarbonate
Base excess
• What is the next step?
110 mmHg
7.19
78 mmHg
23.6 mmol l-1
-2.4 mmol l-1
40% (FiO2 0.4)
normal values
> 75 mmHg on air
7.35 – 7.45
35 – 45 mmHg
22 – 26 mmol l-1
+/- 2 mmol l-1
21 year old woman thrown from horse (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
PaO2
pH
PaCO2
Bicarbonate
Base excess
110 mmHg
7.19
78 mmHg
23.6 mmol l-1
-2.4 mmol l-1
40% (FiO2 0.4)
normal values
> 75 mmHg on air
7.35 – 7.45
35 – 45 mmHg
22 – 26 mmol l-1
+/- 2 mmol l-1
• What is the next step?
• Step 5: Determine the metabolic component
• If the pH < 7.35, is the HCO3- < 22 mmol l-1 (base excess < -2 mmol l-1) –
metabolic acidosis
• If the pH > 7.45, is the HCO3- > 26 mmol l-1 (base excess > +2 mmol l-1) –
metabolic alkalosis
21 year old woman thrown from horse (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
PaO2
pH
PaCO2
Bicarbonate
Base excess
110 mmHg
7.19
78 mmHg
23.6 mmol l-1
-2.4 mmol l-1
40% (FiO2 0.4)
normal values
> 75 mmHg on air
7.35 – 7.45
35 – 45 mmHg
22 – 26 mmol l-1
+/- 2 mmol l-1
In summary:
An acute respiratory acidosis with impaired ventilation.
Respiratory arrest
Initial Information - Use the 5-step approach to analyse the results of an arterial blood sample
I:
Nurses have called a medical emergency
S:
A 65-year-old man has been found collapsed in the respiratory unit
B:
Patient admitted with with severe COPD - initial assessment by the ward
nurse he was found to be apnoeic
A:
A Apnoeic - head tilt chin lift opening manoeuvre
B Nurse is attempting to ventilate with bag-mask, oxygen at 15 l min-1,
Oropharyngeal airway, SaO2 99%
C Easily palpable carotid pulse – 90 bpm – regular (not monitored)
Capillary refill < 3 seconds, IV inserted, BP not recorded
D
AVPU, Glucose 6.2mmoll-1, no medications given recently
E Nil
R:
Please review urgently and an arterial blood gas sample has been taken
Respiratory arrest (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
85% (FiO2 0.85) estimated
normal values
PaO2
147 mmHg
> 75 mmHg on air
pH
7.10
7.35 – 7.45
PaCO2
135 mmHg
35 – 45 mmHg
HCO3-
36 mmol l-1
22 – 26 mmol l-1
BE
+ 12 mmol l-1
+/- 2 mmol l-1
Respiratory arrest (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
85% (FiO2 0.85) estimated
normal values
PaO2
147 mmHg
> 75 mmHg on air
pH
7.10
7.35 – 7.45
PaCO2
135 mmHg
35 – 45 mmHg
HCO3-
36 mmol l-1
22 – 26 mmol l-1
BE
+ 12 mmol l-1
+/- 2 mmol l-1
In summary:
The significant acidaemia (pH 7.10) indicates an acute respiratory acidosis as a
result of the respiratory arrest.
There is pre-existing compensated chronic respiratory acidosis,
the pH would have been close to normal.
Ventilated Post VF Arrest
Initial Information - Use the 5-step approach to analyse the results of an arterial blood sample
I:
Emergency Department staff require assistance
S:
75-year-old woman is admitted to the ED following a VF cardiac arrest.
Spontaneous circulation restored after 2 shocks, but the patient remained
apnoeic and unresponsive.
The arrest witnessed by paramedics had been preceded by 30 min of
severe central chest pain
B:
A:
A Intubated – ETT confirmed in trachea
B Ventilated her with an automatic ventilator tidal volume of 900 ml
rate of 18 breaths min-1, 100% oxygen, Symmetrical chest movement
C Pulse 100 min-1, BP 90/54 mmHg, IV inserted, Cap refill >3seconds
D
AVPU, Glucose 4.8 mmol l-1, 1mg Adrenaline given during
arrest
E Nil, Temp 36.7 oC
R:
Please review urgently and an arterial blood gas sample has been taken
Ventilated Post VF Arrest (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
100% (FiO2 1.0)
normal values
PaO2
192 mmHg
> 75 mmHg on air
pH
7.62
7.35 – 7.45
PaCO2
20 mmHg
35 – 45 mmHg
HCO3-
19 mmol l-1
22 – 26 mmol l-1
BE
- 4 mmol l-1
+/- 2 mmol l-1
Ventilated Post VF Arrest
(continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
100% (FiO2 1.0)
normal values
PaO2
192 mmHg
> 75 mmHg on air
pH
7.62
7.35 – 7.45
PaCO2
20 mmHg
35 – 45 mmHg
HCO3-
19 mmol l-1
22 – 26 mmol l-1
BE
- 4 mmol l-1
+/- 2 mmol l-1
In summary:
A respiratory alkalosis, mild metabolic acidosis.
Diabetic Patient Unwell
Initial Information - Use the 5-step approach to analyse the results of an arterial blood sample
I:
Staff require assistance
S:
An 18-year-old insulin dependent diabetic is unwell and staff concerned
B:
He has been vomiting for 48 h and because he was unable to eat, he has
taken no insulin
A:
A Airway clear/patent
B Breathing spontaneously RR 35 min-1, oxygen 4 l min-1 via Hudson mask,
SpO2 98%
C Pulse 100 min-1, BP 90/54 mmHg, IV inserted, Cap refill >3seconds
D AVPU (Alert earlier), GCS 12 (E3, M5, V4), No insulin given, bedside Blood
sugar “Hi”
E Nil, Temp 36.2 oC, Decreased skin turgor, dry tongue/mouth
R:
Please review urgently and an arterial blood gas sample has been taken
Diabetic Patient Unwell
(continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
PaO2
pH
PaCO2
HCO3BE
129 mmHg
6.89
19 mmHg
4.7 mmol l-1
- 29.2 mmol l-1
30% (FiO2 0.3) estimated
normal values
> 75 mmHg on air
7.35 – 7.45
35 – 45 mmHg
22 – 26 mmol l-1
+/- 2 mmol l-1
The blood glucose is 30 mmol l-1 and there are ketones +++ in the urine
Diabetic Patient Unwell (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
PaO2
pH
PaCO2
HCO3BE
129 mmHg
6.89
19 mmHg
4.7 mmol l-1
- 29.2 mmol l-1
30% (FiO2 0.3) estimated
normal values
> 75 mmHg on air
7.35 – 7.45
35 – 45 mmHg
22 – 26 mmol l-1
+/- 2 mmol l-1
The blood glucose is 30 mmol l-1 and there are ketones +++ in the urine
In summary:
These blood gas results are consistent with severe diabetic ketoacidosis.
Further evidence is the presence of ketones in his urine and the very high blood
glucose.
There is a primary metabolic acidosis with an element of compensation
provided by the respiratory alkalosis.
Hypotension Emergency
Initial Information - Use the 5-step approach to analyse the results of an arterial blood sample
I:
Ward staff activated medical emergency
S:
A 75-year-old man is on the surgical ward has become increasingly
hypotensive over the last 6 h despite 1000 ml 0.9% saline
2 days post operative - laparotomy for a perforated sigmoid colon
secondary to diverticular disease
B:
A:
A Patient speaking – Airway clear
B RR 35 min-1, (SpO2 90%) started on 4 l min-1 oxygen via facemask
SpO2 now poor signal, Symmetrical chest movement
C HR 120 min-1, sinus tachycardia, warm peripheries/sweaty cold centrally,
BP 70/40 mmHg, Capillary Refill 3 seconds
D AVPU, Glucose 5.8 mmoll-1, Urine output 90 ml in the last 6 h
GCS 13 (E3, M6, V4)
E Temperature not recorded, Patient lethargic
R:
Please review urgently and an arterial blood gas sample has been taken
Hypotension Emergency (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
40% (FiO2 0.4) estimated
normal values
PaO2
62 mmHg
> 75 mmHg on air
pH
7.17
7.35 – 7.45
PaCO2
24 mmHg
35 – 45 mmHg
HCO3-
12 mmol l-1
22 – 26 mmol l-1
BE
- 15 mmol l-1
+/- 2 mmol l-1
Hypotension Emergency (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
40% (FiO2 0.4) estimated
PaO2
62 mmHg
> 75 mmHg on air
pH
7.22
7.35 – 7.45
PaCO2
24 mmHg
35 – 45 mmHg
HCO3-
12 mmol l-1
22 – 26 mmol l-1
BE
- 15 mmol l-1
+/- 2 mmol l-1
In summary:
There is a primary metabolic acidosis with an element of compensation. The degree
of this is probably limited by the presence of an acute abdomen.
The most likely diagnosis is sepsis syndrome secondary to intra-abdominal infection.
Out of hospital witnessed arrest
Initial Information - Use the 5-step approach to analyse the results of an arterial blood sample
I:
Nurse has called as paramedics bring in patient
S:
Intubated, ventilated patient arrived post arrest
B:
A 60-year-old man, witnessed out-of-hospital cardiac arrest. The
paramedics arrived after 7 min, during which CPR had not been attempted.
His initial rhythm was VF and the paramedics subsequently restored a
spontaneous circulation after the 3rd shock.
A:
A Intubated
B RR 8-10, FiO2 50%
C Pulse 120 min-1 – SinusTachycardia, BP 150/95, Capillary refill < 2
seconds, IV inserted
D AVPU, Glucose 6.8, Adrenaline 1mg post 2nd shock & Amiodarone 300mg
after 3rd shock
E Cyanosed. Temp 35.7 oC
R:
Please review urgently and an arterial blood gas sample has been taken
Out of hospital witnessed arrest (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
50% (FiO2 0.5)
normal values
PaO2
56 mmHg
> 75 mmHg on air
pH
7.10
7.35 – 7.45
PaCO2
47 mmHg
35 – 45 mmHg
HCO3-
14 mmol l-1
22 – 26 mmol l-1
BE
- 10 mmol l-1
+/- 2 mmol l-1
Out of hospital witnessed arrest (continued)
• Arterial blood gas analysis reveals:
Inspired oxygen
50% (FiO2 0.5)
normal values
PaO2
56 mmHg
> 75 mmHg on air
pH
7.10
7.35 – 7.45
PaCO2
47 mmHg
35 – 45 mmHg
HCO3-
14 mmol l-1
22 – 26 mmol l-1
BE
- 10 mmol l-1
+/- 2 mmol l-1
In summary:
This is a typical ABG result after prolonged cardiac arrest.
There is a mixed metabolic and respiratory acidosis – the predominant component
is metabolic, with significant impairment of oxygenation.
Any questions?
Summary
This workshop has covered:
• The terms used to describe the results of arterial blood gas
•
•
•
•
analysis
The normal ranges for arterial blood gas values
How respiration and metabolism are linked
How to use the 5-step approach to arterial blood gas
interpretation
Some of the common causes of arterial blood gas abnormalities
and what to do to correct them
Advanced Life Support Course
Slide set
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©Australian Resuscitation Council and Resuscitation Council (UK) 2010; updated 2013