Page 383 - Hall et al (2015) Principles of Critical Care-McGraw-Hill

CHAPTER 33: Shock 253

volume resuscitation, cardiac output, hemoglobin, and oxygen satura-
TABLE 33-3 Urgent Resuscitation of the Patient With Shock—Managing
Factors Aggravating the Hypoperfusion State tion are more likely problems.
Which vasopressor is best? Recent randomized controlled trials
Respiratory therapy (RCTs) show no significant survival benefit of any particular vasopressor
Protect the airway—consider early elective intubation in treating hypotension due to shock. 15-18 However, these RCTs all show
Prevent excess respiratory work—ventilate with small volumes that increased β-adrenergic stimulation results in increased heart rate
and increased incidence of arrhythmias (epinephrine>norepinephrine,
Avoid respiratory acidosis—keep Pa low
CO 2 dopamine>norepinephrine, norepinephrine>vasopressin). This adverse
Maintain oxygen delivery—Fi , PEEP, hemoglobin action of β-adrenergic stimulation may be important in some patients.
O 2
Infection in presumed septic shock (see Chap. 64) Addition of low-dose vasopressin infusion to conventional norepineph-
rine infusion may improve survival in patients with less severe septic
Empirical rational antibiosis for all probable etiologies
shock, particularly in patients with a mild degree of sepsis-induced
18
Exclude allergies to antibiotics renal dysfunction. 19
Search, incise, and drain abscesses (consider laparotomy) Inotropes If evidence of inadequate perfusion persists (assessed by clinical
Arrhythmias aggravating shock (see Chap. 36) indicators, by Scv , by direct measurement of cardiac output, etc) despite
O 2
adequate circulating volume (Early Goal-Directed Therapy goal: CVP
Bradycardia
8-12 mm Hg), vasopressors (Early Goal-Directed Therapy goal: >65 mm Hg),
Correct hypoxemia—Fi of 1.0 and hemotocrit, then inotropic agents are indicated (eg, dobutamine
2,3
O 2
Atropine 0.6 mg, repeat × 2 for effect 2-20 µg/kg per minute). Inotropes are not effective when volume resus-
Increase dopamine to 10 mg/kg per minute citation is incomplete. In this case, the arterial vasodilating properties of
inotropes such as dobutamine and milrinone result in a drop in arterial
Add isoproterenol (1-10 mg/min) pressure that is not countered by an increase in cardiac output because
Consider transvenous pacer venous return is still limited by the inadequate volume resuscitation. The
Ventricular ectopy, tachycardia corollary is, if initiation of inotropes results in a significant drop in blood
pressure, then it follows that adequate volume resuscitation is not complete.
+
2+
Detect and correct K , Ca , Mg 2+ The objective of inotrope use is to increase cardiac output to achieve
Detect and treat myocardial ischemia adequate oxygen delivery to all tissues. Organ function (mentation, urine
Amiodarone for sustained ventricular tachycardia output, etc) is the best measure. Of the many alternative clinical and labo-
ratory indicators that should be measured, mixed venous O saturation
Supraventricular tachycardia 2
(when a pulmonary artery catheter is placed) or Scv is useful surrogate
O 2
Consider defibrillation early measures of adequacy of O delivery. Rapidly achieving a goal Scv
20
2
O 2
β-blocker, digoxin for rate control of atrial fibrillation greater than 70% results in a substantial improvement in survival and limits
the systemic inflammatory response so that the subsequent need for fur-
Sinus tachycardia 140/min
ther volume, red blood cell transfusion, vasopressor use, and mechanical
Detect and treat pain and anxiety ventilation is reduced. 3
Midazolam fentanyl drip Steroids Always controversial, steroids are currently not indicated for the
Morphine treatment of shock and uniformly increase the incidence of superinfec-
tion. When septic shock is so severe that it is resistant to high-dose
21
Detect and treat hypovolemia
catecholamine infusion then low-dose hydrocortisone (50 mg IV q6h, or
Metabolic (lactic) acidosis equivalent, with or without fludrocortisone) may enhance the effective-
Characterize to confirm anion gap without osmolal gap ness of catecholamines and may improve the dismal outcome of patients
22
Rule out or treat ketoacidosis, aspirin intoxication in this state. For chronically steroid dependent patients or for those
with frank adrenal insufficiency, corticosteroid treatment is essential.
Hyperventilate to keep Pa of 25 mm Hg
CO 2
Calculate bicarbonate deficit and replace half if pH <7.0 Drugs/Definitive Therapy: During the rapid initial assessment of the patient
in shock and initial resuscitation aimed at supporting respiration and
Correct ionized hypocalcemia
circulation, it is important to consider early institution of other defini-
Consider early dialysis tive therapy for specific causes of shock and early input from consul-
Hypothermia tant experts. When myocardial infarction is the cause of cardiogenic
shock, immediate thrombolysis or angioplasty is considered, using
Maintain skin dry and covered with warmed blankets
intra-aortic balloon pump support and coronary artery bypass surgery
Warm vascular volume expanders when necessary (see Chap. 37). During resuscitation of hypovolemic
9
Aggressive rewarming if temperature <35°C (95°F) shock, continuous and early application of techniques to anticipate,
prevent, or correct hypothermia prevents secondary coagulopathy,
Fi , fraction of inspired O ; P , partial pressure of CO ; PEEP, positive end-expiratory pressure.
coma, and nonresponsiveness to volume and pharmacologic resusci-
O 2 2 CO 2 2
tation. Hemostasis is the immediate goal for hemorrhage because
10
blood pressure by itself is insufficient and can distract from careful it removes the cause of hypovolemic shock and lessens the need for
reassessment of adequacy of oxygen delivery. If urine output increases, further volume expanders, none of which are as effective as keeping
mentation improves, and lactate levels decrease, then vasopressor ther- the patient’s own blood intravascular. Tranexamic acid may reduce
apy has achieved its goals, and there is no need to increase MAP further hemorrhage in trauma patients. Emergent radiologic and surgical
23
even if the MAP that reverses these signs of hypoperfusion is 55 mm Hg. consultation and intervention may be required. Similarly, when septic
If the measures of organ system perfusion are not improved by vaso- shock is secondary to a perforated viscus, an undrained abscess, or
pressor therapy, then arbitrarily driving MAP much above 70 mm Hg rapid spread of infection in devitalized tissue or in tissue planes (gas
is rarely useful and usually detrimental because cardiac output will gangrene, necrotizing fasciitis, etc), then immediate surgical interven-
decrease further and excessive vasoconstrictor tone will impair blood tion is fundamental to survival. Early institution of appropriate anti-
flow distribution. If evidence of hypoperfusion persists, then inadequate biotics has a profound effect on patient survival from septic shock. 24,25
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