HEMODYNAMIC MONTORING

1
HEMODYNAMIC MONTORING
2
Monitoring Circulation

• ECG
• Blood Pressure
• Pulse Oximeter
• CVP

3
Circulation (cont..)

• Pulmonary artery catheter
• Pulse Oximetry
• Skin color

4
ECG

• Documents electrical activity
• may not reflect output
• Wave form varies with lead placement
• know standard lead placement
• St segment analysis

5
Blood Pressure

• Traditional
• Korotkoff (1905)
• Oscillometric
• Roy Adami (1890)
• Invasive

6
Measuring Blood Pressure

• Auscultation - Korotkoff sounds
• Doppler - Reflection of sound waves

7
Measuring Blood Pressure

• Oscillometry - Electronically measures pressure
  at which oscillation amplitude changes
• Arterial tonometry - Pressure required to
  partially occlude the artery supported by a bone

8
Accuracy Depends Upon

• Size of cuff
• cuff too small high BP
• cuff too big low BP
• Site of cuff placement
• increased SBP decreased DBP as BP is measured
  more peripheral

9
Oscillometric

• Measures SBP, DBP MBP
• Mean BP DBP1/3 SBP-DBP
• Controlled by microprocessors
• error less than 5 mm/Hg
• Establish baseline before starting
• Set appropriate cycling interval

10
Arterial Line

• Beat to beat BP
• Provides waveform
• Provides sampling port

11
Transducer

• Converts mechanical impulse to electrical data
• Must be entirely fluid filled
• Use rigid tubing
• Position at level of heart

12
Terms Associated with Transducers

• Strain gauge
• Wheatstone bridge circuit
• Hyper resonance
• Damping

13
Assess Circulation

• Allens test (E.V. Allen, 1929)
• patient makes tight fist for 1 min.
• radial ulnar arteries compressed
• one artery released
• observe color return in hand
• repeat with other artery

14
Allens Test Findings

• Color return
• lt 5 seconds - normal
• 5 - 15 seconds - delayed
• gt 15 seconds - abnormal

15
Pulse Oximetry

• Some machines provide wave form
• Follow Allens test procedure
• Look for return of wave form rather than return
  of color

16
A-Line Information

• SBP
• DBP
• MBP
• Wave form

17
A-Line Wave Form

• Upstroke
• contractility
• Downstroke
• peripheral resistance
• Area under the curve
• cardiac output
• Size varies with ventilation
• hypovolemia

18
Sites for A-Line

• Radial
• Ulnar
• Brachial
• Femoral
• Dorsalis Pedis/Posterior tibial
• Axillary

19
Central Venous Pressure
20
Purpose of CVP line

• Monitoring central venous pressure
• Vascular access
• Access for pulmonary art cath
• Therapeutic uses (VAE)

21
Sites for Insertion of CVP

• Right internal jugular
• Subclavian
• Left internal jugular
• External jugular
• Antecubital
• Femoral

22
CVP Waveforms

• A-wave atrial contraction
• C-wave RV contraction
• X Descent relaxed R atrium
• V wave venous filling of atria
• y descent opening of tricuspid

23
CVP Things to Note

• Large V wave
• papillary muscle ischemia
• tricuspid regurgitation
• Elevated pressure with prominent A and V wave
• diminished RV compliance

24
Things to Note

• Monophasic with lost y descent
• Equalization of CVP, RV and PAOP
• cardiac tamponade

25
Indications for CVP

• Hypovolemia
• large fluid shifts
• trauma
• shock

26
Important Concept

• The CVP is only accurate with normal LV function.
  In the presence of LV dysfunction a pulmonary
  artery catheter is required.

27
When setting up CVP

• Obtain transducer
• Set up separate IV bag and tube
• Coordinate type of CVP line
• Get supplies prior to entering room

28
Complications of CVP

• Carotid puncture
• Dysrhythmias
• Pneumpthorax / hemothorax
• Brachial plexus injury
• Infection

29
Pulmonary Artery Pressure
30
Purpose of PA Monitoring

• Quantitative assessment of cardiopulmonary
  function
• Needed because right heart pressures do not
  always reflect left heart function

31
Indications for PA Catheter

• When the following information is required
• intracardiac pressures
• thermodilution cardiac output
• mixed venous oxygen saturation
• derived hemodynamic indices

32
Derived Parameters

• Cardiac index
• Systemic vascular resistance
• Pulmonary vascular resistance
• Stroke index
• LV stroke work index
• RV stroke work index

33
Know the formulas for these parameters and the
normal values

• Kirby table 21-18
• McIntosh table 6-6

34
Inserting the PA Catheter

• Landmarks same as CVP
• Insert large (8 fr) Cordus
• Float the PA catheter using the characteristic
  waveform to indicate position of the tip.

35
Characteristic Waveforms

• CVP
• Right Ventricle
• Pulmonary artery
• Pulmonary artery occlusion

36
Interpreting the Numbers

• Look at the entire clinical picture
• Dont chase and individual number
• See McIntosh table 6-7

37
Mixed Venous Oxygen

• Reflects oxygen consumption by the cells.
• Oximetrix Swan-Ganz catheter
• Blood gas from proximal port

38
Elevated Mixed Venous O2

• Sepsis
• Pancreatitis
• Carbon Monoxide poisoning
• Portal caval shunt
• Cyanide poisoning
• Continuous wedged balloon

39
Decreased MVO2

• Fever
• Hypoxia
• Low cardiac output
• LV failure
• Increased metabolism

40
Cardiac Output

• Derived from estimates of blood pressure and flow
• Important for management of critically ill
  patients
• Thermodilution through PA catheter is common
  technique

41
CO technique

• Saline injected through PA cath
• Thermistor at tip records decrease in temp as
  fluid is cooled in the PA
• Compute analyzes data and provides a number.

42
Problems with CO Measurement

• CO too high or injectate volume too small
• Temp difference too small
• Improper position of temp sensor

43
Into the future

• Watch for development of Doppler based external
  probe of some sort which will assess cardiac
  output.

44
Transesophageal Echocardiography
45
TEE

• Probe placed in esophagus
• Doppler shifted ultrasound used to create image

46
Uses of TEE

• Wall motion (ischemia)
• Valvular competency
• Blood flow during systole and diastole
• Estimate chamber volume and CO

47
More sophisticated use

• Assess preload
• Determine the presence of air
• Observe regional wall motion

48
Disadvantage of TEE

• Large piece of equipment
• Very expensive
• Requires extensive hands-on training

49
Monitoring Temperature
50
Temperature

• Most patients should have temperature monitored
• All patients receiving general anesthesia must
  have temperature monitored

51
Hyperthermia

• Aggressive warming
• heat pad
• Bair hugger
• small surgical exposure
• Malignant Hyperthermia
• Coexisting disease

52
Hypothermia

• Cold environment
• room temp
• fluids
• prep
• Vasodilators
• Reduced metabolism

53
Does the site of the Temperature monitor really
make a difference?
54
First decide what area of the body you want to
monitor, then decide upon the location of the
probe
55
Sites for Temperature Monitoring

• Oral
• Esophageal
• Tympanic membrane
• Nasopharynx
• Pulmonary artery
• Bladder

56
Sites (continued)

• Rectum
• Skin
• forehead
• axilla
• toe

57
Volatile anesthetics vasodilate and shift the
body heat from the core to the peripheral areas
58
Preventing Hypothermia

• Warm the room
• Heat and humidify gases
• Cover the patient
• Actively heat the patient
• Warm the intravenous fluids

59
Temperature

• Must be monitored on all patients receiving
  general anesthesia

60
Temperature Sites

• Tympanic membrane
• convenient indicator of core temperature
• Skin
• may not reflect core temperature
• skin temp lt 33o - shivering

61
Temperature Site (Contd)

• Esophagus
• Rectum
• Bladder
• Axillary
• Skeletal muscle

62
Effects of General Anesthesia

• Vasodilation
• Reduced metabolism
• Inability to shiver

63
Specific Agents

• Isoflurane
• decreases threshold for vasoconstrictive response
  to hypothermia

64
Temperature Monitoring

• Must monitor all patients receiving general
  anesthesia
• Equipment immediately available for all other
  cases

65
Mechanism of Heat Loss

• Radiation
• Conduction
• Convection
• Evaporation

66
Mechanism of Heat Loss (Contd)

• Evaporation
• respiratory
• body cavities
• skin

67
Average Temperature Loss

• 1o c in the first hour
• 0.3o c each hour thereafter

68
Specific Agents (Contd)

• Regional Anesthesia
• inhibits cold sensation
• metabolic response inhibited
• slower rewarming in PACU
• Narcotics
• induce central hypothermia

69
Specific Agents (Contd)

• Barbiturates
• peripheral vasodilation
• Inhalation agents
• vasodilation
• Muscle relaxants
• prevent shivering

70
Remember

• Shivering increases oxygen consumption by up to
  400
• Extreme cold causes altered hemostasis