Critical-Care Flashcards

1
Q

Rx: ARDS

A
  1. Low volume
  2. Prone position
  3. NM blockade Exp: only interventions known to help
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2
Q

01-Critical-Care

A
  1. Acute organ failure
  2. Acute respiratory failure
  3. Shock
  4. Poisoning

Critical care medicine focuses on the management of acute organ failure and other life-threatening illnesses. Treatment of acute respiratory failure and its common causes, including pneumonia, chronic obstructive pulmonary disease (COPD), and the acute respiratory distress syndrome (ARDS), is an important component of critical care management. The timely diagnosis and rapid treatment of septic, cardiogenic, and hypovolemic shock are crucial to the survival of patients with these life-threatening conditions. Recent emphasis on minimizing and preventing the complications of critical care therapies is also highlighted here. Because toxin exposures often require acute management in a critical care setting, a review of the major types of toxin exposures is included.

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3
Q

Acute-respiratory-failure

Two pathophysiologic causes of acute respiratory failure

Meta: pathophysiologic cause

A

Failure to:

  1. Oxygenate
  2. Ventilate
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4
Q

Acute-respiratory-failure.Hypoxemic

A

Inadequate Pao2 despite high levels of supplemental inspired O2

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5
Q

Acute-respiratory-failure.Hypoxemic

Measures of oxygenation

A
  1. SaO2
  2. PaO2
  3. A-a gradient
  4. PaO2/FiO2
  5. A-a oxygen ratio
  6. Oxygenation index

The arterial oxygen saturation (SaO2), arterial oxygen tension (PaO2), alveolar to arterial (A-a) oxygen gradient, and the PaO2/fraction of inspired oxygen (FiO2) ratio are common measures. Alternatively, the A-a oxygen ratio and the oxygenation index can be used

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6
Q

Acute-respiratory-failure.Hypoxemic

Normal PaO2

A

Conventionally: PaO2 <80 mmHg

Similar to oxygen saturation, an abnormal PaO2 has not been precisely defined because a threshold below which tissue hypoxia predictably occurs has not been identified. However, it seems reasonable to consider a PaO2 <80 mmHg abnormal, although the value should not be considered in isolatio

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7
Q

Acute-Respiratory-Failure.Hypoxemic.AetioCauses

A
  1. RL shunt
  2. VQ mismatch
  3. Reduced diffusion capacity
  4. Alveolar hypoventilation
  5. Low FiO2
  6. Right-to-left shunt: (e.g., pulmonary AVMs, intracardiac right-to-left shunts), or space-filling pulmonary parenchymal lesions (e.g., atelectasis or pneumonia). Will not correct with supplemental oxygen.
  7. ▪Ventilation-perfusion () mismatch: Regional imbalances between blood flow and ventilation (e.g., pulmonary embolism or lung parenchymal disease); corrects, partially or completely, with the addition of supplemental oxygen
  8. Reduced diffusion capacity (e.g., interstitial lung disease, emphysema); may be minimal at rest; more pronounced with exercise
  9. Alveolar hypoventilation (e.g., from central nervous system [CNS] depression, neuromuscular disease, or chest wall abnormality); the only type of hypoxic failure with a normal alveolar-arterial (A-a) gradient
  10. Low fraction of inspired oxygen (Fio2) (e.g., high altitude)
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8
Q

Acute-Respiratory-Failure.Hypoxemic

The only type that has a normal A-a gradient

A

Alveolar hypoventilation

(e.g., from central nervous system [CNS] depression, neuromuscular disease, or chest wall abnormality); the only type of hypoxic failure with a normal alveolar-arterial (A-a) gradient

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9
Q

Acute-respiratory-Failure.Hypoxemic.VQ-Mismatch

Mechanism, examples and effect of oxygenation

A

Regional imbalances between blood flow and ventilation

Eg: PE or parenchymal disease;

Corrects: partially or completely, with the addition of supplemental oxygen

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10
Q

Acute-Respiratory-Failure.Hypoxemic.RL-shunt

Mechanism, example, effect of O2

A
  1. Pathologic vascular communications. Eg: pulmonary AVMs, intracardiac right-to-left shunts
  2. Space-filling parenchymal lesions. Eg: atelectasis or pneumonia.

Will not correct with supplemental oxygen.

I think the reason is that in this situation the blood never gets a chance to be oxygenated. Raising alveolar O2 in other parts of the lung does not help. In the case of a P

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11
Q

Acute-Respiratory-Failure.Ventilatory.EtioCauses

Meta: EtioCause

A

High Paco2 +decreased pH

  1. Increased CO2 production. Eg: sepsis, overfeeding, thyrotoxicosis
  2. Decreased CO2 elimination
    1. Decreased minute ventilation. Eg: CNS depression
    2. Decreased alveolar ventilation. Eg: COPD, increase in dead space from pneumonia or large PE
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12
Q

Acute-Respiratory-Failure.Cyanosis

Cyanosis occurs when deoxyhemoglobin level is greater than 5 g/dL, Sao2 around _%

A

Cyanosis occurs when deoxyhemoglobin level is greater than 5 g/dL, Sao2 around 67%

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13
Q

Pulse-oximeter is unreliable when:

A
  1. Steep part of O2-dissociation curve: ie < 90%
  2. Carboxyhemoglobin or methemoglobin
  3. Shock
  4. Nail polish
  5. Pigmented skin
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14
Q

Mechanical-ventilation.Indications

A
  1. PaO2 < 60 to 70 mm Hg and FiO2 > 80%
  2. PaCO2 ≥45 mm Hg and pH <7.35

Other indications:

  1. high respiratory rate with use of accessory muscles
  2. Inability to protect airway
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15
Q

Measures-of-oxygenation

A
  1. Arterial oxygen saturation (SaO2)
  2. Arterial oxygen tension (PaO2)
  3. A-a oxygen gradient
  4. PaO2/FiO2 ratio
  5. a-A oxygen ratio
  6. Oxygenation index
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16
Q

Acute-respiratory-failure.Hypoxemic

Goal of O2 therapy

A

SaO2 > 88%

or

PaO2 >55 mm Hg

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17
Q

Acute-Respiratory-Failure.Mechanical-Ventilation

Modes

A
  1. Volume cycled
    1. AC
    2. SIMV
  2. Pressure cycled
    1. PRVC
    2. PS
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18
Q

Acute-Respiratory-Failure.Mechanical-Ventilation

AC

A

Assist control: Patient receives a set tidal volume for every initiated breath. A preset number of breaths per minute prevents hypoventilation

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19
Q

SIMV

A

Synchronized intermittent mandatory ventilation (SIMV): Patient receives a set tidal volume for only a designated number of breaths per minute. Additional patient-initiated breaths have no support

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20
Q

PRVC

A

Pressure-regulated volume control (PRVC): Patient receives set tidal volume for every initiated breath as long as the pressure required to deliver remains below a preset value.

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21
Q

Pressure Support

A

Ventilator provides a constant preset pressure for each patient-initiated breath; primarily used in awake patients or as a weaning mode. Should not be used in patients without intact respiratory drive.

22
Q

Auto-PEEP

A

PEEP that is secondary to incomplete exhalation is referred to as auto-PEEP (also called intrinsic PEEP).

23
Q

Acute-Respiratory-Failure.Mechanical-Ventilation

Non-invasive

A
  1. CPAP: Constant pressure provided throughout respiratory cycle
  2. BiPAP: Different pressures provided upon inspiration and expiration
24
Q

ARDS.Causes

A
  1. Sepsis
  2. Pneumonia
  3. Inhalation injury
25
Q

ARDS: cause of death

A

Sepsis and multiorgan system failure

26
Q

ARDS: Definition

A
  1. Acute onset
  2. Diffuse bilateral infiltrates
  3. Pao2/Fio2 ratio less than 200 (Pao2/Fio2 ratio <300 defines acute lung injury [ALI])
  4. No evidence of left-heart failure (PCWP <18 mm Hg)
27
Q

Sepsis: common causes

Meta: ID topic

A

Gram-positive organisms now most common cause of sepsis, followed closely by gram-negative organisms

28
Q

Sepsis: old definition

A
  1. T >38°C or T<36°C)
  2. P >90
  3. RR>24 breaths/min, PaCO2 <32 mm Hg) or ventilation
  4. WBC >12,000/mm3 or <4000/mm3

Pretty weird

29
Q

Sepsis: severe and septic shock

A
  1. Severe: Sepsis + organ failure
  2. Septic shock: hypotension unresponsive to fluids + end-organ damage

Mortality rates 15% to 20% for sepsis; 50% to 60% for septic shock

30
Q

Sepsis: SOFA score

A

(http://clincalc.com/IcuMortality/SOFA.aspx):

  1. Respiratory system – the ratio of arterial oxygen tension to fraction of inspired oxygen (PaO2/FiO2)
  2. CVS – the amount of vasoactive medication necessary to prevent hypotension
  3. Hepatic system – the bilirubin level
  4. Coagulation system – the platelet concentration
  5. Neurologic system – the Glasgow coma score
  6. Renal system – the serum creatinine or urine output
31
Q

Sepsis: qSOFA

A
  1. RR ≥22/minute
  2. Altered mentation
  3. SBP ≤100 mmHg

Easy to calculate since it only has three components, each of which are readily identifiable at the bedside and are allocated one point:

●Respiratory rate ≥22/minute

●Altered mentation

●Systolic blood pressure ≤100 mmHg

The qSOFA score was originally validated in 2016 as most useful in patients suspected as having sepsis outside of the intensive care unit (ICU) [28]. It has since been prospectively validated in the emergency department (ED) and confirmed to be less valuable in the ICU setting

32
Q

Sepsis: EGDT

A
  1. MAP > 65
  2. CVP > 8
  3. urine output > 0.5 mL/kg/hr
  4. Mixed venous O2 sat > 70%
  5. Decreasing lactate level

mean arterial pressure greater than 65 mm Hg, central venous pressure greater than 8 mm Hg, and urine output greater than 0.5 mL/kg/hr; may also include either mixed venous O2 saturation greater than 70% or decreasing lactate levels.

Similar goal-directed therapy late in management (i.e., after 24 hours) does not improve outcomes

33
Q

Shock: signs

A
  1. hypotension;
  2. oliguria;
  3. abnormal mental status;
  4. tachypnea;
  5. cool, clammy skin;
  6. Lactate up
34
Q

Shock: undifferentiated shock, Mx

A

IVF

  1. Epinephrine: anaphylaxis
  2. Pericardiocentesis: tamponade
  3. Chest tube: pneumothorax/hemothorax
  4. Surgery: hemorrhagic shock/valve rupture/dissection
  5. Cardioversion or pacemaker placement: arrhythmias
  6. Antibiotics: sepsis
  7. Cardiac-Cath: MI
  8. Thrombolysis: massive PE
  9. IV hydrocortiosone: adrenal crisis

In patients with undifferentiated hypotension or shock, the clinician should stratify the patient according to the severity of shock and the need for immediate or early intervention so that empiric lifesaving therapies can be administered promptly. Such therapies include intramuscular epinephrine (anaphylaxis), pericardiocentesis (pericardial tamponade), chest tube insertion (tension pneumothorax), surgical intervention (hemorrhagic shock, valve rupture, aortic dissection), cardioversion or pacemaker placement (life-threatening arrhythmias), intravenous antibiotics (sepsis), revascularization procedures (myocardial infarction), systemic thrombolysis (massive pulmonary embolism), and intravenous glucocorticoids (adrenal crisis). (See ‘Risk stratification’ above.)

35
Q

Shock: transfusion threshold

A

7

Without coronary artery disease or active bleeding, a transfusion threshold of hemoglobin of 7 g/dL was as effective as, and possibly superior to, using a transfusion threshold of hemoglobin of 10 g/dL

36
Q

Sepsis: dopamine versus norepinephrine

A
  1. Similar mortality rates.
  2. Dopamine may increase mortality in patients with cardiogenic shock.
  3. Dopamine: more likely to cause tachyarrhythmias
  4. Norepinephrine: more potent vasopressor
37
Q

Shock: Vasopressors: Indxn

A

MAP < 60, SBP drop > 30

Vasopressors are indicated for a MAP <60 mmHg, or a decrease of systolic blood pressure that exceeds 30 mmHg from baseline, when either condition results in end-organ dysfunction due to hypoperfusion. (See ‘Principles’ above.)

Hypovolemia should be corrected prior to vasopressor therapy. Re-evaluate frequently

38
Q

Toxin exposure: exceptions to activated charcoal therapy

A
  1. alkalis
  2. lithium,
  3. iron, and
  4. insecticides
39
Q

Toxin-Exposure: TCA-overdose: effects

A

anticholinergic, α-adrenergic blocking, and adrenergic uptake–inhibiting properties

40
Q

Toxin-Exposure: TCA overdose: predictor of toxicity

A

QRS > 100

41
Q

Toxin-Exposure: TCA-overdose: signs

A

Arrhythmias, hypotension, and

anticholinergic effects:

hyperthermia, flushing, dilated pupils, ileus, retention, and sinus tachycardia

42
Q

Toxin-exposure: Sedatives

A
  1. Benzos
  2. Opiates
43
Q

Toxin-Exposure: toxidromes

A
  1. Sympathomimetic: Cocaine
  2. Anticholinergic: TCA, Jimson weed
  3. Hallucinogenic: PCP
  4. Opioid: Heroin
  5. Sedative-hypnotic: Benzos, alcohols
  6. Cholinergic: Organophosphate
  7. Serotonin: MAOI, SSRI, TCA
44
Q

Toxin-Exposure: EvaluationParameters

Meta: DxApproach, EvaluationParameter

A
  1. Mental status
  2. Pupils
  3. Vital signs
  4. Reflexes
  5. Specific features
45
Q

Toxin-Exposure: TCA poisoning: Mx

A

Sodium bicarbonate

Alkalinization to serum pH of 7.4 to 7.5 with IV sodium bicarbonate is indicated to reduce occurrence of arrhythmias

46
Q

Toxin-exposure: β-blocker

A

Glucagon

IVF, pacing and vasopressor or inotrope with β1 activity

47
Q

Toxin-Exposure: Methemoglobulinemia: Rx

A

methylene blue (MB) —

Acquired methemoglobinemia may be life-threatening when there is an acute increase above baseline in the level of methemoglobin amounting to more than 30 percent.

No RCTs: MB can be life-saving and is considered the treatment of choice. MB, given intravenously in a dose of 1 to 2 mg/kg over five minutes,

48
Q

Toxin-Exposure: Alcohol-poisoning-Rx

Methanol, ethylene glycol, isopropranol

A

Fomepizole

49
Q

Shock: PA parameters

A
  1. cardiogenic shock: low CO and high PCWP.
  2. pericardial tamponade: low CO and equalization of RAP, pulmonary artery diastolic pressure, and PCWP.
  3. PE, air embolus: low CO with high PAP and RAP.
  4. Septic shock: high CO with low-to-normal filling pressures.
50
Q

Sepsis: Ddx

A
  1. Acute myocardial infarction
  2. Acute pulmonary embolus
  3. Acute pancreatitis
  4. Fat emboli syndrome
  5. Acute adrenal insufficiency
  6. Acute gastrointestinal hemorrhage
  7. Overzealous diuresis
  8. Transfusion reactions
  9. Adverse drug reactions
  10. Procedure-related transient bacteremia
  11. Amniotic fluid embolism