PHYSIOLOGIC MONITORING OF SURGICAL PATIENT Flashcards
HEMODYNAMIC MONITORING
Indications for Arterial Catheterization
⦁ need for continuous BP monitoring
⦁ need for frequent arterial blood sampling
HEMODYNAMIC MONITORING
Conditions that need continuous & accurate BP monitoring
⦁ shock status
⦁ hypertensive crisis
⦁ surgery in high risk patients
⦁ use of potent vasoactive or inotropic drugs
⦁ controlled hypotensive anesthesia
⦁ situations that may lead to rapid changes in cardiac function
absolute contraindications to ART cath
NONE!
relative contraindications to ART cath
⦁ bleeding problems (hemophilia)
⦁ anticoagulant therapy
⦁ presence of a vascular prosthesis
⦁ local infection
- Sites for Arterial Catheterization
⦁ Radial artery ⦁ Axillary artery ⦁ Femoral artery ⦁ Dorsalis Pedis artery ⦁ Superficial temporal artery ⦁ Brachial artery
most commonly used site for arterial catheterization
radial artery
RADIAL ARTERY FOR ART CATH
- hand has dual blood supply (radial & ulnar)
- most commonly used site
- simple cannulation
- low complication rate
- Modified Allen’s Test = assess ulnar artery
- Doppler technique, Plethysmography, Pulse oximetry
MODIFIED ALLEN’S TEST
hand elevated, pt clenches fist x about 30 seconds. Pressure applied over ulnar & radial arteries (occlude both). Still elevated, hand is opened from fist - should be blanched/observe pallor. Then ulnar pressure is released, but maintain radial pressure. Color should return within 5-15 seconds
⦁ if color returns within 5-15 seconds, the Allen’s test = considered normal
⦁ if color fails to return, test considered abnormal, and it suggests that the ulnar artery supply to the hand is not sufficient = indicates that it may not be safe to use the radial artery. Try other hand…
AXILLARY ARTERY FOR ART CATH
- for long term monitoring
- large size
- close proximity to aorta
- deep location
- technical difficulty in insertion
- located near neurovascular structures
FEMORAL ARTERY FOR ART CATH
- large size & superficial location
- prone to atherosclerosis
- difficult to keep clean (near groin…)
SUPERFICIAL TEMPORAL ARTERY FOR ART CATH
- surgical exposure is required
- neurologic complications observed
BRACHIAL ARTERY FOR ART CATH
- for short term use only
- risk of median nerve contracture (Volkman’s contracture)
ARTERIAL CATHETERIZATION
- for short term
- for long term
- modified Allen’s test
- median nerve contracture risk (Volkman’s)
- prone to atherosclerosis
- easily inserted
- difficult to insert
- difficult to keep clean
- neurologic complication risk / surgical insertion
short term = brachial artery
long term = axillary artery
modified Allen’s test = radial artery
Volkman’s contracture risk = brachial artery
prone to atherosclerosis = femoral artery
easily inserted = radial artery
difficult to insert = axillary artery
difficult to keep clean = femoral artery
neurologic risk = superficial temporal artery
COMPLICATIONS OF ARTERIAL CATHETERIZATION
⦁ failure to cannulate
⦁ hematoma
⦁ disconnection from monitoring system
⦁ infection (if catheter in place > 4 days, if surgical insertion done. Local inflammation occurs)
⦁ retrograde cerebral embolization (AV fistula / pseudoaneurysm) - severe pain & distal necrosis
preferred site = radial artery
CVP MONITORING (central venous pressure)
CVP = direct measurement of blood pressure in right atrium & vena cava
- acquired by threading a central venous catheter (subclavian double lumen central line) into any of several large veins
- the line is threaded so that the tip of the catheter rests in the lower 3rd of the superior vena cava. The pressure monitoring assembly is attached to the distal port of a multilumen central vein catheter
why monitor cvp?
- In seriously ill patients, the vital problem is determining the proper amount of fluids and blood requirements necessary to maintain an optimal blood volume in the preop, operative, and postop phase
- CVP monitoring = reliable procedure to properly and promptly evaluate the optimal fluid & blood requirements in these patients
- the procedure removes a lot of the guess work in rapid restoration and maintenance of adequate circulation without fear of overloading the heart
- CVP = measured anywhere in the SVC or IVC or their immediate tributaries, such as the Innominate and the Common Iliac Veins
- CVP determined by a complex interaction of
⦁ blood volume
⦁ cardiac pump action
⦁ vascular tone - CVP measurement serves as an index of circulating blood volume relative to the cardiac pump action
- CVP determined by a complex interaction of
⦁ blood volume
⦁ cardiac pump action
⦁ vascular tone
- CVP measurement serves as an index of
circulating blood volume relative to the cardiac pump action
CVP will reflect the ability of the Cardiac Pump Action to handle the returning blood volume at that particular time
INDICATIONS FOR CVP MONITORING
⦁ when massive blood replacement is instituted rapidly in rapid exsanguinating type of bleeding
⦁ In acute blood volume deficit in cases where the pt had surgery for a strangulating type of intestinal obstruction, where rapid fluid replacement is indicated
⦁ In obscure cases of shock immediately post-op, whether hypovolemic due to internal bleeding, or non-hypovolemic from MI
⦁ In elderly patients with limited cardiac reserve, who are undergoing difficult & time consuming operations
⦁ In surgical patients with anuria due to possible renal shutdown
normal CVP
4-7
Normal CVP = 4 - 7 cm/H2O
o a low CVP (0-3) indicates that the circulating blood volume is below the normal blood volume that the heart can handle
o a high CVP (8-20) indicates that the circulating blood volume is more than the heart can handle
a low CVP indicates that
a high CVP indicates that
o a low CVP (0-3) indicates that the circulating blood volume is below the normal blood volume that the heart can handle
o a high CVP (8-20) indicates that the circulating blood volume is more than the heart can handle
INDICATIONS FOR CENTRAL VENOUS CATHETERIZATION
⦁ access for fluid therapy ⦁ access for drug infusion ⦁ parenteral nutrition ⦁ CVP monitoring (aspirate air embolism) ⦁ placement of cardiac pacemaker / vena cava filters ⦁ hemodialysis access
OTHER USES FOR CENTRAL VENOUS CATHETERIZATION
⦁ useful in hypotensive patients
⦁ tracings for arrhythmias
⦁ provides information about the relationship between intravascular volume and right ventricular function
most common complication of venous catheter in subclavian vein
pneumothorax
sites of venous catheterization for CVP monitoring
⦁ Subclavian vein
⦁ Internal Jugular vein
⦁ External jugular vein
⦁ Basilic vein
SUBCLAVIAN VEIN CATHETERIZATION
- easiest to cannulate
- **Pneumothorax = most common complication
- difficult to control bleeding
easiest vein to cannulate
subclavian
but difficult to control bleeding
pneumothorax = most common complication
most common complication of internal jugular vein cath
arterial puncture
INTERNAL JUGULAR VEIN CATHETERIZATION
- lower risk of pneumothorax
- ***Arterial puncture = most common complication
technique for venous catheterization for CVP monitoring
- A polyethelene tube size French 8 and 42 inches long is inserted at the Basilic Vein just above the elbow and pushed up to 20 inches
- Connect an Intravenous administration set to the venous catheter through which IV fluid may be administered
- A Manometer is connected to IV set with a three way stopcock. Zero point should be at the level of the atrium or approximately at Mid-axillary line
PULMONARY ARTERY CATHETER (PAC) - SWAN-GANZ purpose =
diagnostic - used to detect heart failure, sepsis, monitor therapy, and evaluate the effects of drugs
- allows direct, simultaneous measurement of pressures in
⦁ right atrium
⦁ right ventricle
⦁ pulmonary artery
⦁ filling pressure (“wedge” pressure) of the left atrium
SITES FOR PAC
⦁ Right Internal Jugular Vein = shortest & straightest path to heart
⦁ Left Subclavian = doesn’t require PAC to pass at an acute angle to enter SVC (compared to right subclavian or internal jugular)
⦁ Femoral veins - distant sites, so can be difficult, especially if right sided cardiac chambers are enlarged. Often, fluoroscopic assistance is necessary. These sites are compressible, however, and may be preferred if risk of hemorrhage is high
shortest & straightest path to heart for PAC insertion
right internal jugular vein
CVP MONITORING COMPLICATIONS
- catheter malposition
- dysrhythmias
- embolization
- vascular injury
- cardiac, pleural, mediastinal, neurologic injury
INDICATIONS FOR RESPIRATORY MONITORING
- decision making for the need of mechanical ventilation
- assessment of response to therapy
- optimize ventilatory management
- decision to wean from ventilator
volume of air moved in or out of the lung in a single breath
tidal volume
maximal volume at expiration after a maximal inspiration
vital capacity
total volume of air leaving the lung each minute
minute volume
the portion of tidal volume that does not participate in gas exchange
physiologic dead space
GAS MONITORING
- reported as directly measured partial pressures (PO2 & PCO2)
- used of pulse oximeters for continuous measurements
- Blood gas analysis - gives info about
⦁ efficiency of gas exchange
⦁ adequacy of alveolar ventilation
⦁ acid-base status
graphic display of CO2 concentration in wave form
capnography
PULSE OX FOR GAS MONITORING
reliable, but not quite a real time estimation of the arterial Hgb saturation.
Has wide clinical acceptance
GASTRIC TONOMETRY
relatively non-invasive monitoring of the adequacy of aerobic metabolism in organs whose superficial mucosal lining is extremely vulnerable to low flow changes and hypoxemia
- assesses perfusion based on stomach’s mucosal pH by measuring gastric luminal PCO2
- tonometer balloon inserted into gastric lumen - reflects intramucosal CO2
PURPOSE OF RENAL MONITORING
- the kidney = an excellent monitor of the adequacy of perfusion
- done to prevent renal failure
- predicts drug clearance to allow for proper dose adjustment
urine output for renal monitoring
- commonly monitored, but may be misleading
- normal urine output = 0.5 mL / kg / hr
- correlates with GFR
- high output may not accurately reflect GFR, however (ex: Diabetes Insipidus - not enough ADH or resistant to ADH –> continuously urinating)
- may be affected by other factors
foley catheter for renal monitoring
- flexible tube passed through urethra and into bladder to drain urine
- foley catheter = most common type of indwelling urinary catheter
- has 2 separated lumens running down its length
⦁ one lumen = open at both ends, and drains urine into a collection bag
⦁ other lumen = has a valve on the outside end and connects to a balloon at the tip - inflated with sterile water when it lies inside bladder to stop it from slipping out - foley catheter commonly made from silicone rubber or natural rubber
- should only be used when indicated, as use increases the risk of UTIs
BUN
- BUN = affected by GFR and Urea production
- BUN is increased in TPN, GI bleeding, trauma, sepsis, steroid use
- BUN is decreased in starvation, liver disease
- BUN = not always a reliable test
BUN increased with
TPN GI bleeding steroid use trauma sepsis
BUN decreased with
starvation
liver disease
SERUM CREATININE
- more reliable than BUN
- directly proportional to creatinine production
- inversely related to GFR
- not affected by protein or nitrogen production, or rate of fluid flow through tubules
- related to muscle mass
currently the most reliable method
of assessing GFR
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CREATININE CLEARANCE
CREATININE CLEARANCE
- used if values of plasma creatinine are affected by muscle disease
- serial determination of urine is done and is CURRENTLY THE MOST RELIABLE METHOD OF ASSESSING GFR
tubular function tests
- the most reliable test to distinguish pre-renal azotemia from tubular necrosis*
- requires simultaneous collected urine & blood samples
- the most reliable test to distinguish pre-renal azotemia from tubular necrosis*
tubular function tests
neurological monitoring
- for early recognition of cerebral dysfunction
- to facilitate prompt intervention & treatment
⦁ Glasgow Coma Scale
⦁ Bedside serial neuro checks by nursing staff
⦁ ICP (normally 7-15 mmHg for a supine adult)
⦁ Cerebral Perfusion Pressure (CPP) = difference between MAP & ICP (> 70 mmHg)
normal ICP
7-15 mmHg for supine adult
CPP (cerebral perfusion pressure) =
MAP - ICP
should be > 70 mmHg
EEG
reflects spontaneous and on-going electrical activity in the brain
transcranial ultrasound
- monitors cerebral blood flow
- detects vasospasms
Measures the relationship of blood flow to O2 consumption
jugular venous oximetry
for neurological monitoring
ratio of CO2 produced to O2 consumed, while food is being metabolized
RESPIRATORY QUOTIENT OF FOOD (RQ)
metabolic monitoring
temperature monitoring
- rectal
- oral
- axillary
- middle ear
- esophageal
