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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: • • • • ↓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 • • • • • • 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.