PHYSIOLOGIC
MONITORING
I.
Hemodynamic Monitoring
- provides information as to the C-P status of
the patient
- traditional clinical assessment are usually
unreliable
- major changes in the cardiovascular status
may not be clinically obvious
- invasive techniques must be utilized
A. Arterial Catheterization
1. Indications
a. Need for continuous blood
pressure monitoring.
b. Need for frequent arterial blood
sampling.
Conditions that need continuous
and accurate BP monitoring:
i. shock states
ii. hypertensive crisis
iii. surgery in high risk patients
iv. use of potent vasoactive or
inotropic drugs
v. controlled hypotensive
anesthesia
vi. situations that may lead to rapid
changes in cardiac function
2. Contraindications
- no ABSOLUTE contraindication
to arterial catheterization
- RELATIVE contraindications are:
a. bleeding problems
(hemophelia)
b. anticoagulant therapy
c. presence of a vascular prosthesis
d. local infection
3. Sites of Catheterization
a. radial artrery
- dual blood supply
- most commonly used site
- simple canulation
- low complication rate
- modified “Allen’s” test – assess
ulnar artery
- Doppler technique, plethysmography,
pulse oximetry
b. axillary artery
- for long term monitoring
- large size
- close proximity to the aorta
- deep location
- technical difficulty in insertion
- located near neurovascular
structures
c. femoral artery
- large size and superficial
location
- prone to atherosclerosis
- difficult to keep clean
d. dorsalis pedis
e. superficial temporal artery
- surgical exposure is required
- neurologic complications observed
f. brachial artery
- for short term use only
- median nerve contracture
(Volkman’s contracture)
*Complications of arterial catheterization
1. failure to cannulate
2. hematoma
3. disconnection from monitoring system
4. infection
- catheters in place for more than 4 days
- surgical insertion
- local inflammation
5. retrograde cerebral embolization
6. A-V fistula / pseudoaneurysm
7. severe pain, distal necrosis
B. Central Venous Catheterization
1. Indications
a. access for fluid therapy
b. access for drug infusion
c. parenteral nutrition
d. CVP monitoring
e. other indications
- aspirate air embolism
- placement of cardiac
pacemaker / vena cava filters
- hemodialysis access
*Central Venous Pressure Monitoring
1. useful in hypotensive patients
2. tracings for arrythmias
3. gives information about the relationship between
intravascular volume and right ventricular function
4. use of a water manometer for pressure
measurements
5. Normal CVP measurement – 5-10 mmH2O
2. Sites of catheterization
a. subclavian vein
- easiest to cannulate
- pneumothorax most common complication
- difficult to control bleeding
b. internal jugular vein
- lower risk of pneumothorax
- arterial puncture most common complication
c. external jugular vein
d. basilic vein
*Complications
1. catheter malposition
2. dysrythmmias
3. embolization
4. vascular injury
5. cardiac, pleural, mediastinal, neurologic injury
II. Respiratory Monitoring
- monitoring ventilation and gas exchange
* Indications
1. Decision making for the need of
mechanical ventilation.
2. Assessment of response to therapy.
3. Optimize ventilatory management.
4. Decision to wean from ventilator.
A. Ventilation monitoring
1. Tidal volume – volume of air moved in or out of the lung an
a single breath
2. Vital capacity – maximal volume at expiration after a maximal
inspiration
3. Minute volume – total volume of air leaving the lung each minute
4. Phsiologic dead space – the portion of tidal volume that does not
participate in in gas exchange
a. anatomic dead space
b. phsiologic dead space
B. Gas Monitoring
- reported as directly measured partial pressures (PO2
and PCO2)
- use of pulse oximeters for continuous measurements
1. Blood gas analysis – information
about:
a. efficacy of gas exchange
b. adequacy of alveolar ventilation
c. acid – base status
2. Capnography
- graphic display of CO2 concentration in wave form
- available systems
a. infrared analysis
b. mass spectrometry
c. Raman scattering
d. disposable colorimetric devices
e. semi-quantitive measurement on the endtidal CO2 concentration
3. Pulse oximetry
- reliable, real time
estimation of the arterial
Hgb saturation
- wide clinical acceptance
4. Gastric Tonometry
- relatvely non-invasive monitor of
adequacy of aerobic metabolism in
organs whose superficial mucosal lining is
extremely vulnerable to low flow changes
and hypoxemia
III. Renal Monitoring
- the kidney is an excellent monitor of adequacy
of perfusion
- prevention of renal failure
- predict drug clearance and proper dose
adjustment
A. Urine Output
- commonly monitored but may be misleading
- normal urine output  0.5 ml/kg/hour
- correlates with glomerular filtration rate (GFR)
- high output may not accurately reflect GFR ex.
Diabetes Insipidus
- may be affected by other factors
B. Glomerular Function Tests
1. Blood Urea Nitrogen (BUN)
a. affected by GFR and urea
production
b. increased in TPN, GI bleeding,
trauma, sepsis, steroid use
c. lowered in starvation, liver
disease
d. not a reliable test
2. Plasma Creatinine
a. more accurate than BUN
b. directly proportional to creatinine
production
c. inversely related to GFR
d. not affected by protein or
nitrogen production or rate of fluid
flow through tubules
e. related to muscle mass
3. Creatinine Clearance
a. used if values of plasma
creatinine are affected by muscle
disease
b. serial determination of urine is
done and is currently the most
reliable method of assessing GFR
C. Tubular Function Tests
1. The most reliable test to distinguish prerenal azotemia from tubular necrosis
2. Requires simultaneous collected
urine and blood samples
IV. Neurologic Monitoring
- early recognition of cerebral dysfunction
- facilitate prompt intervention and treatment
A. Intracranial Pressure Monitoring
1. Cerebral Perfusion Pressure >70mmHg
2. Glasgow Coma Scale
B. Electrophysiologic Monitoring
- reflects spontaneous and on-going electrical activity in the brain
C. Transcranial Ultrasound
- monitors cerebral blood flow
- detects vasospasm
D. Jugular Venous Oximetry
- measures relationship of blood flow to O2 consumption
V. Metabolic Monitoring
A. Caloric Demands
B. Respiratory Quotient of Food
VI. Temperature Monitoring
A. Rectal
B. Middle Ear
C. Esophageal