Ch 1- 3 Flashcards Preview

The ICU Book by Paul Marino > Ch 1- 3 > Flashcards

Flashcards in Ch 1- 3 Deck (54)
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1
Q

Calculate cardiac compliance

A

change in end-diastolic volume (ΔEDV)/change in end-diastolic pressure (ΔEDP)

1
Q

When is end-diastolic pressure not representative of preload?

A

when ventricular compliance is abnormal

2
Q

what are the most common causes of decrease in ventricular compliance? (2)

A

ventricular hypertrophy and ischemic heart disease

3
Q

define cardiac afterload

A

in the intact heart, afterload force is equal to the peak tension in the ventricle during systole

4
Q

how is ventricular tension calculated?

A

T = Pr, P = pressure at the end of systole, r = radius of the ventricle at the end of diastole

5
Q

Effects of negative thoracic pressure on ventricular function

A

impedes ventricular emptying by opposing contraction during systole

6
Q

define pulsus paradoxus

A

effect responsible for the exaggerated transient decrease in systolic blood pressure in excess of 15mmHg occurring during spontaneous inspiration

7
Q

What is the effect of positive-pressure mechanical ventilation on arterial blood pressure?

A

increases, increasing stroke volume and cardiac output

8
Q

What is the principal determinant of ventricular afterload?

A

Impedence, made up of compliance (elasticity of larger arteries) and resistance (opposition to steady flow in smaller arteries/arterioles)

9
Q

define the formula for vascular resistance

A

Resistance (R) = Pressure differential (ΔP)/rate of blood flow (Q)

10
Q

define the formula for systemic vascular resistance

A

Systemic vascular resistance (SVR) = mean systemic arterial pressure (SAP) - mean right atrial pressure (RAP)/cardiac output (CO)

11
Q

define the formula for pulmonary vascular resistance under normal circumstances

A

Pulmonary vascular resistance (PVR) = mean pulmonary artery pressure (PAP) - mean left arterial pressure (LAP)/cardiac output (CO)

12
Q

How is afterload measured/calculated indirectly?

A

Changes in the slow of ventricular function is used

13
Q

What outside factors (2) should be considered when measuring afterload indirectly?

A

Ventricular compliance and myocardial contractility

14
Q

What is the standard measure of contractility?

A

Ventricular pressure acceleration can be measured during cardiac catheterization by measuring the time from the onset of systole to the opening of the aortic valve

15
Q

When does vascular compression become a problem in patients on positive-pressure mechanical ventilation?

A

When alveolar pressure exceeds hydrostatic pressure in pulmonary capillaries

16
Q

Define the formula for pulmonary vascular resistance when the alveolar pressure exceeds average left atrial pressure

A

PVR = mean pulmonary artery pressure (PAP) - alveolar pressure (Palv)/CO

17
Q

What is the principal determinant of whole blood viscosity?

A

Concentration of erythrocytes (hematocrit)

18
Q

What is normal average hematocrit?

A

45%

19
Q

What is the ratio of the viscosity of blood to plasma?

A

3:1

20
Q

Describe changes that occur in flow as blood passes through capillaries smaller than 0.3mm

A

shear thinning: viscosity decreases and velocity increases (plasma > erythrocytes)

21
Q

Calculate arterial O2 content

A

1.34 x Hb x ratio of arterial oxygenated hemoglobin to total hemoglobin (SaO2)

22
Q

What is the principal determinant of the oxygen content of the blood?

A

Hemoglobin concentration

23
Q

What measure should be used to evaluate the efficiency of gas exchange in the lungs?

A

PaO2

24
Q

Given the amount of oxygen stored in the AV system, how long can aerobic metabolism be maintained just from stored oxygen?

A

3-4 minutes

25
Q

What is the maximal oxygen extraction from systemic capillaries?

A

40-50%

26
Q

What ratio of oxygen delivery rate (DO2) to oxygen dissociation rate(VO2) is required to avoid anaerobic metabolism?

A

DO2:VO2 = 4:1

27
Q

What are imidazole groups?

A

They buffer hemoglobin and are effective in the pH range 6-8

28
Q

What is the buffer range of bicarbonate, why is this important?

A

5.1-7.1, this is important because hemoglobin is a more effective buffer than bicarbonate

29
Q

What is the name for the increase in CO2 binding and buffering affinity that occurs after desaturation?

A

The Haldane effect

30
Q

What is the most frequently isolated bacteria on the hands of ICU personnel?

A

Staph epidermidis

31
Q

What is the most important consideration in using iodine as a germicide?

A

It must be left in contact with the skin for a few minutes

32
Q

What is the most effective germ prevention method for C. Difficile?

A

Gloved hands, hand washing, no antiseptics work

33
Q

Sterile or non-sterile gloves: central venous catheterization

A

sterile

34
Q

Sterile or non-sterile gloves: peripheral venous catheterization

A

nonsterile, as long as the hands don’t touch the catheter

35
Q

Sterile or non-sterile gloves: peripherally inserted central catheter (PICC)

A

sterile

36
Q

Sterile or non-sterile gloves: arterial catheterization

A

sterile

37
Q

Sterile or non-sterile gloves: closed space drain placement

A

sterile

38
Q

Sterile or non-sterile gloves: insertion of epidural catheter

A

sterile

39
Q

Surgical mask or Negative pressure isolation: Hemophilus influenza (type b) epiglottitis, pneumonia or meningitis

A

surgical mask

40
Q

Surgical mask or Negative pressure isolation: mycobacterium tuberculosis (pulmonary or laryngeal TB)

A

negative-pressure isolation

41
Q

Surgical mask or Negative pressure isolation: Neisseria meningitides pneumonia or meningitis

A

surgical mask

42
Q

Surgical mask or Negative pressure isolation: measles

A

negative-pressure isolation

43
Q

Surgical mask or Negative pressure isolation: diphtheria (pharyngeal)

A

surgical mask

44
Q

Surgical mask or Negative pressure isolation: respiratory mycoplasma

A

surgical mask

45
Q

Surgical mask or Negative pressure isolation: Varicella or disseminated zoster

A

negative-pressure isolation

46
Q

Surgical mask or Negative pressure isolation: group A strep pharyngitis or pneumonia

A

surgical mask

47
Q

Surgical mask or Negative pressure isolation: viral respiratory infections

A

surgical mask

48
Q

What is the average blood exchange of a puncture wound with a hollow needle?

A

One microliter

49
Q

What is the risk of HIV seroconversion from a single needlestick?

A

0.30%

50
Q

What is the risk of HIV seroconversion from a single exposure of broken skin or mucous membranes?

A

0.09%

51
Q

What is the follow up protocol after Hepatitis B vaccination?

A

Serum anti-HBs level should be measured 2 months afterwards. If it is <10mIU/mL, the 3-dose series should be repeated.

52
Q

What is the risk of HCV seroconversion from a single needlestick?

A

1.80%

53
Q

What is the protocol for follow up after confirmed HCV needlestick injury?

A

Serial testing monthly for 6 months.