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Shock
Shock
A broad term that describes a physiologic state where oxygen delivery to the
tissues is inadequate to meet metabolic requirements, causing global
hypoperfusion
TYPES OF SHOCK
1- Cardiogenic Shock:
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↓MAP = ↓ CO (HR x Stroke Volume) x ↑SVR
Decreased Contractility - (Myocardial Infarction)
Mechanical Dysfunction – (Severe Aortic Stenosis)
Arrhythmia – (Atrial fibrillation)
Cardiotoxicity - (B blocker and Calcium Channel Blocker Overdose)
2- Obstructive Shock:
↓MAP = ↓ CO (HR x Stroke Volume) x ↑SVR
Heart is working but there is a block to the outflow
– Massive pulmonary embolism
– Cardiac tamponade
– Tension pneumothorax
Obstruction of venous return to heart
– Vena cava syndrome - eg. neoplasms
3- Hypovolemic Shock:
↓MAP = ↓ CO (HR x Stroke Volume) x ↑SVR
Decreased Intravascular volume (Preload) leads to Decreased Stroke Volume
– Hemorrhagic - trauma, GI bleed, ectopic pregnancy
– Hypovolemic - burns, GI losses, dehydration, Diabetic Ketoacidosis
4- Distributive Shock:
↓MAP = ↑CO (HR x SV) x ↓ SVR
– Loss of Vessel tone
• Septic and Toxic Shock Syndrome
• Anaphylactic (drugs)
– Decreased sympathetic nervous system function
• Neurogenic - C spine or upper thoracic cord injuries
Empiric Criteria for Shock
4 out of 6 criteria have to be met
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Ill appearance or altered mental status
Heart rate >100
Respiratory rate > 22
Urine output < 0.5 ml/kg/hr
Arterial hypotension > 20 minutes duration
Lactate > 4
The shock index
• is easily calculated (heart rate divided by systolic blood pressure)
and can provide clues to the severity of the patient's condition.
• A normal index ranges from 0.5-0.7; repeated values >1.0 indicate
decreased left ventricular function and are associated with higher
mortality.
Laboratory values should be
examined, but do not wait for results
to begin your treatment.
Case 1
• 24 year old male , Previously healthy, Lives in a malaria endemic
area (PNG), Brought in by friends after a fight - he was kicked in
the abdomen. He is agitated, and won’t lie flat on the stretcher
• HR 92, BP 126/72, SaO2 95%, RR 26
Case 2
• 23 year old woman Has been fatigued and short of breath for
a few days. She fainted and family brought her in hospital
• They tell you she has a heart problem. HR 132, BP 76/36, SaO2
88%, RR 30, Temp 36.3. Appearance - obtunded
• Cardiovascular exam - S1, S2, irregular, murmer, JVP is
increased , no edema
• Chest - bilateral crackles, accessory muscle use
• Abdomen - unremarkable
• Rest of exam is normal
Case 3
• 36 year old woman Hitted by a car. She is brought into the
hospital 2 hrs after accident with Short of breath. She has been
complaining of chest pain
• HR 126, SBP 82, SaO2 70%, RR 36, Temp 35
• Obtunded, Accessory muscle use
• Trachea is deviated to Left
• Heart - distant heart sounds
• Chest - decreased air entry on the right, broken ribs,
subcutaneous emphysema
• Abdominal exam - normal
• Apart from bruises and scrapes no other signs of trauma
Fluid
replacement
therapy
Acid-Base Balance
Disturbances
Hydrogen ion homeostasis
Acids are produced continuously during normal metabolism.
(provide H+ to blood)
pH = - log (H+)
H+ ion concentration of blood varies between narrow limits
pH of the blood= 7.35 – 7.45
Constant H+ concentration within physiological limits is physiologically
important to preserve the enzyme activity and metabolism
Sources of acids of blood:
1- Volatile acids: - Carbon Dioxide CO2 (H2CO3)
2- Nonvolatile acids:
1- Organic acids:
- Lactic Acid from anaerobic glycolysis
- Ketone bodies after fatty acid oxidation
2- Inorganic acids from protein catabolism
- Sulphuric Acid
- Phosphoric Acid
Assessment of Acid-Base Balance
Normal pH of blood is not an indication of acid-base balance.
Accordingly, in order to assess acid-base balance (status) of blood ,
we should assess pH & buffer concentration of blood
Relation between pH & buffer
Henderson-Hasselbach Equation
pH
=
[HCO3-]
6.1 + log --------------------------------pCO2 + 0.225
1-Metabolic Acidosis
↓↓ HCO3-
Causes
:
I- Increased production of H+
Common Causes of increased H+ (acids) in the blood:
1- Increased endogenous acid production.
- Diabetic ketoacidosis (increased ketone bodies in blood)
- Lactic acidosis (increased lactic acid in blood).
2-Ingestion of acids (or substance that produces an acid)
- Poisons: as salicylate (aspirin) overdose
- Methanol ingestion
- High protein diet.
II-decreased acid (H+) excretion by the kidney: in renal failure.
III- Loss of bicarbonate in GIT: e.g. in diarrhea
2-Respiratory Acidosis
↑↑ CO2
Causes
Impaired carbon dioxide excretion and thus blood pCO2 increases.
caused by any pulmonary (lung) cause resulting in hypoventilation.
1-Chronic respiratory acidosis: occurs due to chronic obstructive
airway diseases.
Chronic bronchitis
Emphysema
Bronchial asthma
2-Acute respiratory acidosis: occurs due to acute respiratory failure
Cardiac arrest
Respiratory muscle paralysis (poliomyelitis)
Depression of the respiratory centre in the brain
by: cerebral disease or drugs
3-Metabolic ALkalosis
↑↑ HCO3-
The primary abnormality in metabolic alkalosis is the increased plasma
bicarbonate level. (HCO3-).
Causes:
Less common
1- Intake of a large amounts of alkali as sodium bicarbonate:
(if intake is more than 1000 mmol/day)
More common
2- Loss of H+ (acids) from the body:
1- From the kidneys (increased excretion of acids, H+ ions):
a- Mineralcorticoid (aldosterone) excess
b- Severe potassium deficiency
2- From the GIT (increased loss acids, H+ ions): vomiting and gastric wash
4- Respiratory Alkalosis
↓↓ CO2
Causes:
The PCO2 is reduced due to:
Hyperventilation which may be due to:
1- Respiratory centre stimulation as in cases of:
Anxiety
Cerebral disease (infection, tumour)
2- pulmonary embolism (hypoxia).
3- Fevers (shivering)
4- Rib fractures
Blood Gas Report
•Acid-Base Information
• pH
• PCO2
• HCO3 [calculated vs measured]
•Oxygenation Information
• PO2 [oxygen tension]
• SO2 [oxygen saturation]
Practice Problem 1
• George Kent is a 54 year old widower with a history of chronic obstructive
pulmonary disease and was rushed to the emergency department with
increasing shortness of breath, pyrexia, and a productive cough with
yellow-green sputum. Upon examination, crackles and wheezes can be
heard in the lower lobes; he has a tachycardia and a bounding pulse.
Measurement of arterial blood gas shows pH 7.3, PaCO2 68 mm Hg, HCO3
28 mmol/L, and PaO2 60 mm Hg. How would you interpret this?
• A. Respiratory Acidosis, Uncompensated
B. Respiratory Acidosis, Partially Compensated
C. Metabolic Alkalosis, Uncompensated
D. Metabolic Acidosis, Partially Compensated
• Answer: B. Respiratory Acidosis, Partially Compensated
• The patient has respiratory acidosis (raised carbon dioxide) resulting from
an acute exacerbation of chronic obstructive pulmonary disease, with
partial compensation.
Practice Problem 2
Carl, an elementary student, was rushed to the hospital due to vomiting and a
decreased level of consciousness. The patient displays slow and deep breathing , and he
is lethargic and irritable in response to stimulation. He appears to be dehydrated—his
eyes are sunken and mucous membranes are dry—and he has a two week history of
polydipsia, polyuria, and weight loss. Measurement of arterial blood gas shows pH 7.0,
PaO2 90 mm Hg, PaCO2 23 mm Hg, and HCO3 12 mmol/L; other results are Na+ 126
mmol/L, K+ 5 mmol/L, and Cl- 95 mmol/L. What is your assessment?
A. Respiratory Acidosis, Uncompensated
B. Respiratory Acidosis, Partially Compensated
C. Metabolic Alkalosis, Uncompensated
D. Metabolic Acidosis, Partially, Compensated
Answer: D. Metabolic Acidosis, Partially, Compensated
The student was diagnosed having diabetes mellitus. The results show that he
has metabolic acidosis (low HCO3 -) with respiratory compensation (low CO2).
Practice Problem 3
A cigarette vendor was brought to the emergency department of a hospital after she fell
into the ground and hurt her left leg. She is noted to be tachycardic and tachypneic.
Painkillers were carried out to lessen her pain. Suddenly, she started complaining that she
is still in pain and now experiencing muscle cramps, tingling, and paraesthesia.
Measurement of arterial blood gas reveals pH 7.6, PaO2 100 mm Hg, PaCO2 31 mm Hg,
and HCO3 25 mmol/L. What does this mean?
A.Respiratory Alkalosis, Uncompensated
B. Respiratory Acidosis, Partially Compensated
C. Metabolic Alkalosis, Uncompensated
D. Metabolic Alkalosis, Partially Compensated
Answer: A. Respiratory Alkalosis, Uncompensated
The primary disorder is acute respiratory alkalosis (low CO2) due to the pain and anxiety
causing her to hyperventilate. There has not been time for metabolic compensation.
Practice Problem 4
Ricky’s grandmother is suffering from persistent vomiting for two days now. She appears
to be lethargic and weak and has myalgia. She is noted to have dry mucus membranes
and her capillary refill takes >4 seconds. She is diagnosed as having gastroenteritis and
dehydration. Measurement of arterial blood gas shows pH 7.5, PaO2 85 mm Hg, PaCO2
40 mm Hg, and HCO3 34 mmol/L. What acid-base disorder is shown?
A.Respiratory Alkalosis, Uncompensated
B. Respiratory Acidosis, Partially Compensated
C. Metabolic Alkalosis, Uncompensated
D. Metabolic Alkalosis, Partially Compensated
Answer: C. Metabolic Alkalosis, Uncompensated
The primary disorder is uncompensated metabolic alkalosis (high HCO3 -). As CO2 is the
strongest driver of respiration, it generally will not allow hypoventilation as
compensation for metabolic alkalosis.
Practice Problem 5
Mrs. Johansson, who had undergone surgery in the post-anesthesia care unit (PACU), is
difficult to arouse two hours following surgery. Nurse Florence in the PACU has been
administering Morphine Sulfate intravenously to the client for complaints of post-surgical
pain. The client’s respiratory rate is 7 per minute and demonstrates shallow breathing.
The patient does not respond to any stimuli! The nurse assesses the ABCs (remember
Airway, Breathing, Circulation!) and obtains ABGs STAT! Measurement of arterial blood
gas shows pH 7.10, PaCO2 70 mm Hg and HCO3 24 mEq/L. What does this mean?
A.Respiratory Alkalosis, Partially Compensated
B. Respiratory Acidosis, Uncompensated
C. Metabolic Alkalosis, Partially Compensated
D. Metabolic Acidosis, Uncompensated
Answer: B. Respiratory Acidosis, Uncompensated
The results show that Mrs. Johansson has respiratory acidosis because of decreased pH and
increased PaCO2 which mean acidic in nature. Meanwhile, it is uncompensated because
HCO3 is within the normal range.
Practice Problem 6
Baby Angela was rushed to the Emergency Room following her mother’s complaint that
the infant has been irritable, difficult to breastfeed and has had diarrhea for the past 3
days. The infant’s respiratory rate is elevated and the fontanels are sunken. The
Emergency Room physician orders ABGs after assessing the ABCs. The results from the
ABG results show pH 7.35, PaCO2 27 mmHg and HCO3 19 mEq/L. What does this mean?
A.Respiratory Alkalosis, Compensated
B. Metabolic Acidosis, Uncompensated
C. Metabolic Acidosis, Compensated
D. Respiratory Acidosis, Uncompensated
Answer: C. Metabolic Acidosis, Compensated
Baby Angela has metabolic acidosis due to decreased HCO3 and slightly acidic pH. Her pH
value is within the normal range which made the result fully compensated.
Practice Problem 7
Mr. Wales, who underwent post-abdominal surgery, has a nasogastric tube. The nurse on
duty notes that the nasogastric tube (NGT) is draining a large amount (900 cc in 2 hours)
of coffee ground secretions. The client is not oriented to person, place, or time. The
nurse contacts the attending physician and STAT ABGs are ordered. The results from the
ABGs show pH 7.57, PaCO2 37 mmHg and HCO3 30 mEq/L. What is your assessment?
A.Metabolic Acidosis, Uncompensated
B. Metabolic Alkalosis, Uncompensated
C. Respiratory Alkalosis, Uncompensated
D. Metabolic Alkalosis, Partially Compensated
Answer: B. Metabolic Alkalosis, Uncompensated
The postoperative client’s ABG results show that he has metabolic alkalosis because of an
increased pH and HCO3. It is uncompensated due to the normal PaCO2 which is within 35
to 45 mmHg.
Practice Problem 8
Client Z is admitted to the hospital and is to undergo brain surgery. The client is very
anxious and scared of the upcoming surgery. He begins to hyperventilate and becomes
very dizzy. The client loses consciousness and the STAT ABGs reveal pH 7.61, PaCO2 22
mmHg and HCO3 25 mEq/L. What is the ABG interpretation based on the findings?
A. Metabolic Acidosis, Uncompensated
B. Respiratory Alkalosis, Partially Compensated
C. Respiratory Alkalosis, Uncompensated
D. Metabolic Alkalosis, Partially Compensated
Answer: C. Respiratory Alkalosis, Uncompensated
The results show that client Z has respiratory alkalosis since there is an increase in the pH
value and a decrease in PaCO2 which are both basic. It is uncompensated due to the
normal HCO3 which is within 22-26 mEq/L.
Practice Problem 9
Three-year-old Adrian is admitted to the hospital with a diagnosis of asthma and
respiratory distress syndrome. The mother of the child reports to the nurse on duty that
she has witnessed slight tremors and behavioral changes in her child over the past four
days. The attending physician orders routine ABGs following an assessment of the ABCs.
The ABG results are pH 7.35, PaCO2 72 mmHg and HCO3 38 mEq/L. What acid-base
disorder is shown?
A. Respiratory Acidosis, Uncompensated
B. Respiratory Acidosis, Fully Compensated
C. Respiratory Alkalosis, Fully Compensated
D. Metabolic Alkalosis, Partially Compensated
Answer: B. Respiratory Acidosis, Fully Compensated
The patient has respiratory acidosis (raised carbon dioxide) resulting from asthma and
respiratory distress syndrome, with compensation having normal pH value within 7.35to
7.45, increased PaCO2 which is acidic and increased HCO3 which is basic.
Practice Problem 10
Anne, who is drinking beer at a party, falls and hits her head on the ground. Her friend
Liza dials “911” because Anne is unconscious, depressed ventilation (shallow and slow
respirations), rapid heart rate, and is profusely bleeding from both ears. Which primary
acid-base imbalance is Anne at risk for if medical attention is not provided?
A. Metabolic Acidosis
B. Metabolic Alkalosis
C. Respiratory Acidosis
D. Respiratory Alkalosis
Answer: C. Respiratory Acidosis
One of the risk factors of having respiratory acidosis is hypoventilation which may be due
to brain trauma, coma, and hypothyroidism or myxedema. Other risk factors
include COPD, Respiratory conditions such as pneumothorax, pneumonia and status
asthmaticus. Drugs such as Morphine and MgSO4 toxicity are also risk factors of
respiratory acidosis.