8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
1/105
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
2/105
Monitoring in Anaesthesia
and Intensive Care
2
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
3/105
Monitoring: A Definition ... interpret available clinical data to help
recognize present or future mishaps orunfavorable system conditions
... not restricted to anesthesia(change clinical data above to system data to apply to
aircraft and nuclear power plants )
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
4/105
What is monitoring?
Physiologic parameter & Patient safety parameter
Clinical skills & Monitoring equipment
Data collection, interpretation, evaluation, decision
Problem seeking, Severity assessment, Therapeuticassessment, Evaluation of Anesthetic interventions
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
5/105
Patient Monitoring and Management
Involves Things you measure (physiological measurement, such as
BP or HR)
Things you observe (e.g. observation of pupils) Planning to avoid trouble (e.g. planning induction of
anesthesia or planning extubation)
Inferring diagnoses (e.g. unilateral air entry may meanendobronchial intubation)
Planning to get out of trouble (e.g. differential diagnosis
and response algorithm formulation)
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
6/105
Level of monitoring Routine / Specialize / Extensive
Non-equipment / Non-invasive / Minimally invasive
/ Penetrating / Invasive / Highly invasive
Systematic Respiratory / Cardiovascular / Temperature/Fetal Neurological / Neuro-muscular / Volume status & Renal
Standards for basic intraoperative monitoring ( ASA)
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
7/105
Standards for basic intraoperative monitoring
( ASA :American Society of Anesthesiologists)
Standard I Qualified anesthesia personnel shall be present in the
room throughout the conduct of all GA, RA, MAC
Standard II During all anesthetics, the patients respiratory
(ventilation, oxygenation), circulation and temperature
shall be continually evaluated
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
8/105
Monitoring in AnesthesiaOBJECTIVES:1. Guidelines to the practice of anesthesia and patient monitoring
2. Elements to monitor(Anesthesia depth, Oxygenation, Ventilation, Circulation, Temperature)2.1. ECG2.2. Pulse Oximetry ( Function, Values, Limitations)2.3. Blood Pressure (methods, indications, limitations, Insertion sites, values)2.4. central venous line and pressure (methods, indications, limitations,
Insertion sites and it's advantages, Complications, values)
8
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
9/105
Monitoring in AnesthesiaOBJECTIVES:2.5. Capnography and EtCO2 (Uses, Measurement, values, factorsaffecting EtCO2)
2.6. Cyanosis2.7. The oxyhemoglobin dissociation curve (interpretation, causes ofLeft and right shifting , key values, O2-Content of Blood)2.8. Temperature ( Methods, Values, sites)
3. Normal values for a healthy adult undergoing anesthesia
9
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
10/105
Guidelines to the practice of anesthesia and patient monitoring:
Monitoring in the Past
1. Visual monitoring ofrespiration and overallclinical appearance
2. Finger on pulse
3. Blood pressure10
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
11/105
Monitoring in the Past
Finger on the pulse
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
12/105
Harvey Cushing Not just a famous neurosurgeon but the father of anesthesia monitoring
Invented and popularized the anesthetic chart
Recorded both BP and HR
Emphasized the relationship between vital signs andneurosurgical events ( increased intracranial pressure leads to hypertension and bradycardia )
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
13/105
Guidelines to the practice of anesthesia and patient monitoring:
1. Qualified anesthesia personnel shall be present inthe room throughout the conduct of :
- all general anesthetics- regional anesthetics- monitored anesthesia care
2. A completed pre-anesthetic checklist . (history, physical exam, lab investigations, NPO policy)
13
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
14/105
Guidelines to the practice of anesthesia and patientmonitoring: 3. An anesthetic record.
- in general anaesthesia, regional anesthesia, or monitored IVconscious sedation H R and BP shoul d be measured every 5min.
- also time, dose and route of drugs and fluids should be charted
4. During all anesthetics , the patients
- oxygenation- ventilation- circulation shal l be continously evaluated !- temperature
14
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
15/105
MONITORING
BP
MAP
Temp
RR
O2 sat
HR
15
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
16/105
Elements to Monitor :
Patients with local or regional anesthesia provide verbalfeedback regarding well being.
Onset of general anesthesia signaled by lack of response toverbal commands, in addition to loss of blink reflex to lighttouch.
Inadequate anesthesia can be signaled by : Facial grimacingor movement of arm or leg. But with muscle relaxants ( fully
paralysis), it can be signaled by : Hypertension, tachycardia,
tearing or sweating. Excessive anesthesia can be signaled by :
Cardiac depression, bradycardia, and Hypotension.And also may result in hypoventilation, hypercapnia andhypoxemia when muscle relaxants is not given.
I. Anesthetic Depth:
16
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
17/105
Elements to Monitor :
Clinically, monitored by patient color ( with adequateillumination ) and pulse oximetry .
Quantitavely monitored by using oxygen analyzer, equippedwith an audible low oxygen concentration alarm.
III. Temperature Continuous temperature measurements monitoring is
mandatory if changes in temperature are anticipated orsuspected.
II. Oxygenation :
17
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
18/105
Elements to Monitor :
Clinically, monitored by pulse palpation, heart auscultationand monitoring intra-arterial pressure or oximetry.
Quantitavely using ECG signals and arterial blood pressuremeasurements every 5 min.
V. Ventilation Clinically, monitored through a correctly positioned
endotracheal tube, also observing chest excursions, reservoir bag displacement, and breath sounds over both lungs.
Quantitavely by ETCO2 analysis , equipped with an audibledisconnection alarm.
Arterial blood gas analysis for assessing both oxygen andventilation.
IV. Circulation :
18
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
19/105
Monitoring: Electrocardiogram ECG:
A 3 or 5 lead electrode system is used for ECG monitoring in the OR.
The 3 lead system has electrodes positioned on the right arm, left arm and chestposition. ( placed in the left anterior axillary line at the 5 th interspace, referred
to as V5 ). Lead II is usually monitored by this system.
The 5 lead system adds a right leg and left leg electrodes, which allowsmonitoring v1, v2, v3, AVR, AVL, AVF and V5.
II and V5 very important !
ST segment
19
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
20/105
Monitoring: Electrocardiogram ECG:
Identification of P waves in lead II and its association with the QRScomplex is useful in distinguishing a sinus rhythm from otherrhythms.
Analysis of ST segment is used as an indicator of MI. ( Dep.-ischemia/ elev.-infarction )
Over 85% of ischemic events can be detected by monitoring ST seg.of leads II and V5.
20
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
21/105
Monitoring: Pulse Oximetry:
Allows beat to beat analysis of oxygenation.
Depends on differences in light absorption between oxyHb anddeoxyHb.
Red and Infra-red light frequencies transmitted through atranslucent portion. (finger-tip or earlobe)
Microprocessors then analyze amount of light absorbed by the 2wavelengths, comparing measured values, then determining
concentrations of oxygenated and deoxygenated forms. (oxy- anddeoxy-) 21
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
22/105
PULSEOXIMETRY is for OXYGENATION
Principle : Spectrophotometry & Plethysmography
relies on the differing absorption of light, at different wavelengths by the variousstates of oxyhaemoglobin
- HbO2 has a higher absorption at 940 nm (blue light)
- Hb has a higher absorption at 660 nm (red light)
the light signal following transmission throughthe tissues has a pulsatile component
-
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
23/105
- two LEDs : one emitting red light (660 nm) and theother a blue light (940nm) on the finger nail
- on the other side of the finger : photo sensor (photocell) detects the transmitted light
- the LEDs are switched on and off at 30 Hz to detectthe cyclical changes in the signal due to pulsatilearterial blood flow
- by calculating the absorption at the twowavelengths the processor can compute the
proportion of haemoglobin which is oxygenated
Hb HbO
HbO p
C C
C OS
2
2
2
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
24/105
Pulse oximeters measure:1. The oxygen saturation of haemoglobin in arterial blood- which i s a measure o f the average am ount o f o xygen b ound to each
haem oglob in m olecu le
- Haemoglobin is a compound of iron (haem) and globin chains.- Each globin chain is linked to one atom of iron, each of which can carry 4
molecules of oxygen , and as each molecule of oxygen contains two atoms ofoxygen (O2), each haemoglobin molecule can carry 8 atoms of oxygen .
This makes haemoglobin a very efficient means of oxygen transport: each gram ofhaemoglobin can carry 1.34ml of oxygen.
2. The pulse rate - in beats per minute, averaged over 5 to 20seconds.
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
25/105
A pulse oximeter is affected by :
ambient light shivering
abnormal haemoglobins ( carboxyhaemoglobin, methaemoglobin, dyes as methylene blue and bilirubin )
pulse rate and rhythm
vasoconstriction poor tissue perfusion ( shock, low CO, cold extremities )
NOT affected by : dark skin or anaemia.
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
26/105
A pu lse oxim eter g ives no in formation abo ut :
The oxygen content of the blood The amount of oxygen dissolved in the blood
The respiratory rate or tidal volume i.e . ventilation The cardiac output or blood pressure ?
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
27/105
Monitoring: Blood Pressure BP :
o Methods of BP measurement:
1. Simplest method of BP measurement,estimating the SBP, is by palpating the returnof arterial pulse as cuff is deflated (Riva-Rocci).
2.auscultation of the Kortokoff sounds on deflation
(providing both SBP and DBP)Mean Arterial PressureMAP = DBP + 1/3(SBP DBP)MAP = ( SBP + 2 DBP ) / 3
27
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
28/105
MEASUREMENT OF ARTERIAL PRESSURE
INDIRECT measurement (non-invasive)- signals generated by the occlusion of a major artery using a cuff
- gives not continous but intermittent measurements
- palpation method ( Riva Rocci)- auscultation of the Korotkoff sounds
- osccilometry method
DIRECT measurement (invasive and continous)
di h d f (1)
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
29/105
o Indirect Methods of BP measurement (1)
1. Riva Rocci: simplest method of BP measurement, estimating onlythe SBP, is by palpating the return of arterial pulse as cuff isdeflated.
2. Auscultation of the Korotkoff sounds (1905)on deflation created by the turbulent blood flow in the artery
(providing both SBP and DBP)Mean Arterial Pressure (MAP) = DBP + 1/3(SBP DBP)
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
30/105
Indirect Methods of BP measurement (2)
3. OSCCILOMETRY - a microprocessor controlled oscillometer. DINAMAP- a pressur e tr ansducer that digital izes signal s ( microprocesor).- rapid, accurate ( 9 mmHg) measurements of SBP, DBP, MAP and HR
- SAP corresponds to the onset of rapidly increasing oscillations- MAP corresponds to the maximal oscillation at the lowest cuff pressure- DAP corresponds to the onset of rapidly decreasing oscillations
LIMITATIONS:
- tendency to overestimate at low pressures and underestimate at high pressures - errors : movements, arrhythmias or BP fluctuations- compressive peripheral nerve injuries (repeated measurements )
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
31/105
Cuff Size
Too small cuff will result in false high blood pressure reading
Too large cuff will result in false low blood pressure reading
f rom
Ba
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
32/105
DIRECT Measurement of the BP invasive : catheter into the artery
METHODS
1. open Liquid column method (obsolete) , measures only MAP13.4 cm. H2O = 10 mm.Hg.
2. Liquid manometers (obsolete)
3. Electromechanical transducers :- conversion of mechanic signal into an electric signal
- and then electronically converted and displayed as :
SAP,DAP and MAP .
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
33/105
Electromechanical - TRANSDUCERS
The diaphragm :- is moved by arterial pulsations which push the saline column
- should be thin, small and rigid !
Transducers :
- based upon strain gauge principle : stretching (by PRESSURE ) a wire orsilicone crystal changes its electrical resistance
- connected to a wheatstone bridge circuit : so that the voltage output is proportionate to the pressure applied it
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
34/105
The 3 major problems may occur :
1. Improper zeroing and zero drift
2. Improper transducer / monitor calibration
3. Inadequate dynamic response of system : RF and damping
Resonant (natural) Frequency (RF) = frequency at which a system oscillates whenstimulated.
- if the frequency of an input signal (i.e., pressure waveform) approaches the RF of asystem : progressive amplification of the output signal occurs,
a phenomenon known as ringing.
Th ARTERIAL PRESSURE W f
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
35/105
The ARTERIAL PRESSURE Waveform
ARTERIAL WAVEFORM isa complex sine-wave The fundamental frequency (FF) or the 1-st harmonic is equal to the HR
( ex: for HR 60 b/min = 1 beat / sec = 1 cycle/sec = 1Hz.) physiologic peripheral arterial waveforms have a FF = 3 to 5 Hz
MONITORING SYSTEM The RF should be at least at least 5 times higher than the highest frequency in the
input signal or better : approx.10 times the FF
at least FR >20 Hz to avoid ringing and systolic overshoot
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
36/105
The ARTERIAL PRESSURE Waveform
The damping coefficient (DC) is a measure of how quickly an oscillating systemcomes to rest
method to test the DC: the fast-flush test ( square wave test) optimal damping
- underdamping = overestimates SAP and underestimates DAP
- overdamping = underestimates SAP and overestimates DAP
- both cases however MAP is relatively accurate
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
37/105
REDUCING ARTIFACTS IN A-LINES
Lines free of kinks and clots
Air Bubbles : small amount may augment systolic pressure reading, while largeamount cause an over-damped system
One stopcock per line
Heparinized saline flushed maintaining patency
Transducer should be electronically balanced or re-zeroed because the zeropoint may drift if the room temperature changes
to have an adequate damping = flushing TEST
Short and rigid : catheter and lines
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
38/105
Monitoring: Blood Pressure BP:
o Methods of BP measurement:
3. Automated non-invasive BP measurements.METHODOLOGY: a microprocessor controlled oscillometer
(Dinamap) which is used routinely intraoperatively. It
allows automatic inflation of the BP cuff at preset timeintervals, sending readings into a pressure transducer thatdigitalizes them. This technique gives rapid, accurate ( 9mmHg) measurements of SBP, DBP, MAP and HR several
times a minute. LIMITATIONS: Errors occur due tomovements, arrhythmias or BP fluctuations due torespiration. 3 5 minutes intervals is recommended to
prevent compressive peripheral nerve injury due to repeatedrapid measurements.
38
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
39/105
Monitoring: Blood Pressure BP:
o Methods of BP measurement:
4. Invasive BP measurements.(Arterial BP):
Indications: Rapid moment to moment BP changes Frequent blood sampling Major surgeries (cardiac, thoracic, vascular) Circulatory therapies: vasoactive drugs, deliberate
hypotension Failure of indirect BP: burns, morbid obesity Sever metabolic abnormalities Major traumaThe radial artery at the wrist is the most
common site for an arterial catheter.Alternatives are femoral, brachial anddorsalis pedis. 39
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
40/105
Central Venous line and Pressure (CVP)
Catheter inserted into the SVC providing an estimate ofthe right atrial and ventricular pressures .
Serial CVP measurements are more useful than a singlevalue in order to assess blood volume, venous tone andright ventricular performance. HR, BP and CVPresponse to a volume infusion (100 500 ml) is also auseful test of right ventricular performance.
40
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
41/105
Central Venous line and Pressure (CVP)
Indications: CVP monitoring provides Right Atrial and RightVentricle pressures
Advanced Cardiopulmonary disease + major
operation
Secure vascular access for drugs
Secure access for fluids + traumatic pts
Aspiration of entrained air: sitting craniotomies
Inadequate peripheral IV access41
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
42/105
Central Venous Line:PERFORMANCE of Right Internal Jugular Vein
Internal jugular (Int. Jug.) vein lies in groovebetween sternal and clavicular heads ofsternocleidomastoid muscle
It is lateral and slightly anterior to carotid artery
Aseptic technique, head down
Insert needle towards ipsilateral nipple
Seldinger method: 22 G finder; 18 G needle,guide-wire, scalpel blade, dilator and catheter
Observe ECG and maintain control of guide-wire
Ultrasound guidance; Chest-Xray post insertion. 42
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
43/105
Advantages of Right Int. Jug. vein
Consistent, predictable anatomic location Readily identifiable landmarks
Short straight course to Superior Vena Cava Easy access for anesthesiologist at patientshead
High success rate, 90-99%
43
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
44/105
Complications of Central lines (jugular):
Bleeding Injury to surrounding
structures as carotid artery Pneumothorax Arrhythmia
44
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
45/105
Central Venous line Alternative Sites Subclavian vein:
Easier to insert versus Int. Jug. vein Better patient comfort v. Int. Jug. Higher Risk of pneumothorax- 2%
External jugular: Easy to cannulate if visible. no risk of pneumothoroax, high risk or bleeding 20%: cannot access central circulation
45
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
46/105
Central Venous Pressure (CVP )Monitoring
Reflects pressure at junction of vena cava + RA CVP is driving force for filling RA + RV CVP provides estimate of:
Intravascular blood volume RV preload
Trends in CVP are very useful Measure at end-expiration Central Venous Pressure (CVP): 1-10 mmHg
46
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
47/105
SWAN GANZ = PA CATHETER
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
48/105
SWAN-GANZ catheterWaveform during Insertion
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
49/105
PA CATHETER
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
50/105
PA CATHETER Zone III allows for
uninterrupted bloodflow and a continuouscommunication withdistal intracardiacpressures. (PAand PVexceed Palv)
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
51/105
PAC Th dil ti
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
52/105
PAC-Thermodilution
The change of the blood s temperature in is measured in the pulmonary arteryusing the PAC thermistor
The thermistor records the temperature change and the monitor electronicallydisplays a temperature/time curve.
The CO is inversely proportional to :- the temperature change- the area under the curve
( PAC measures the Pulm.CO = Global CO if no intracardiac shunt )
C h d E CO2
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
53/105
Capnography and EtCO2
Capnometry : is the numerical measurement of CO 2 concentrationduring inspiration and expiration.
Capnogram : refers to the continuous display of the CO 2concentration waveform sampled from the patients airway duringventilation.
Capnography : is the continuous monitoring of a patientscapnogram. 53
C h d E CO2
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
54/105
Capnography and EtCO2 End-tidal CO 2 monitoring is standard for all patients undergoing
GA with mechanical ventilation.
It is an important safety monitor and a valuable monitor of the patients physiologic status, and it has been an important factor in reducinganesthesia-related mortality and morbidity.
CO 2 monitoring is considered the best method for verifying successfulintubation and extubation procedures .
It helps in assessment of the adequacy of ventilation and an indirect
estimate of PaCO 2.
Also it aids in diagnosis of PE, recognition of a partial airway obstruction,and indirect measurement of airway reactivity (bronchospasm).
ETCO 2 levels have also been used to predict outcome of resuscitation.
C h d E CO2
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
55/105
Capnography and EtCO2 Measurement of ETCO2 Sampling the patients respiratory gases near the airway . Using infra-red gas analysis or mass spectrometry on the values and
concentrations obtained.
Provided that when sampling, inspired CO 2 value should be nearzero. (i.e. ETCO 2 value is a function of CO 2 production, alveolarventilation and pulmonary circulation; excluding inspired CO 2).
During general anesthesia, with absence of ventilation perfusion
abnormalities, difference between PaCO 2 and ETCO 2 is about 5 mmHg (PaCO2 = 40 mmHg, ETCO2 = 35 mmHg)
Increases or decreases in ETCO2 values maybe the result of
increases or decreases in production and elimination .
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
56/105
Capnography and EtCO2
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
57/105
Capnography and EtCO2
Normal
Esophageal 0 ! > 4 curves !
Cardiac arrest bronhospasm
Curare cleft spontaneous
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
58/105
exhausted CO2 absorber
IMV
Expiratory Valve
Inspiratory valve
Hyper and hypo VENTILATION
Cyanosis
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
59/105
Cyanosis Defined as the presence of 5 g./dL of deoxygenated
hemoglobin (deoxy Hb). i.e. Hb level = 15 g/dL, 5 g/dL release O 2 which leaves 10 g/dL of
oxyhemoglobin
SaO 2 = OxyHb / (OxyHb + DeoxyHb) = 10 / (10 + 5) = 66%
SaO 2 of 66% corresponds to PaO 2 of 35mmHg.
In anemic patients the oxygen tension at which cyanosis isdetectable will be even lower.
i.e. Hb level = 10 gm/dL, 5 gm/dL release O 2 SaO 2 = OxyHb / (oxyHb + DeoxyHb) = 5 / (5 + 5) = 50%
SaO 2 of 50% corresponds to PaO 2 of only 27 mmHg.
Th h l bi di i ti
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
60/105
The oxyhemoglobin dissociation curve
It is a sigmoid curve that describes the relationship betweenoxygen tension (PaO 2) and binding (SpO 2).
When PaO 2 is low, the hemoglobin affinity to oxygen fallsrapidly , explaining the sharp sloping .(PaO 2< 60 mmHg)
The oxyhemoglobin dissociation curve
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
61/105
The oxyhemoglobin dissociation curve A decrease in PaO 2 of less than 60 mmHg (corresponding to SpO 2
90 %) results in a rapid fall in the oxygenation saturation.
The lowest acceptable O 2 saturation level is 90%.Left And Right Shifts of the
Oxyhemoglobin Dissociation CurveRight Left
Decreased affinity of Hb for O 2. Increased affinity of Hb for O 2.
Causes: Inc. PCO 2 Hyperthermia
Acidosis Increased altitude Increased 2,3-DPG Sickle Cell Anemia Inhalational anesthetics
Causes: Dec. PCO 2 Hypothermia
Alkalosis Fetal hemoglobin Decreased 2,3-DPG Carboxyhemoglobin Methemoglobin
Th h l bi di i ti
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
62/105
The oxyhemoglobin dissociation curve Key Values:a. At PO
2 100 mmHg, Hb 100% saturation .
b. At PO 2 40 mmHg, Hb 75% saturation.c. At PO 2 27 mmHg, Hb 50% saturation.
Oxygen content of blood: is the total amount of O 2 carried in blood, including bound and
dissolved O 2.O2 content = (O 2-binding capacity * % saturation) + O 2 dissolved
O2-binding capacity = maximal amount of O 2 bound to Hb at 100 % sat.
The dissolved O 2 isnt measured by oximetry but by blood gasanalysis.
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
63/105
Monitoring Temperature
Objectiveaid in maintaining appropriate body temperature
Applicationreadily available method to continuously monitortemperature if changes are intended, anticipated orsuspected
Methodsthermostattemperature sensitive chemical reactions
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
64/105
Monitoring Temperature
Potential heat loss or risk of hyperthermianecessitates continuous temperaturemonitoring
Normal heat loss during anesthesia averages0.5 - 1 C per hour, but usually not more that 2 -3 C
Temperature below 34C may lead tosignificant morbidity
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
65/105
Monitoring Temperature
Hypothermia develops when thermoregulationfails to control balance of metabolic heat
production and environment heat loss Normal response to heat loss is impaired
during anesthesia Those at high risk are elderly, burn patients
neonates, spinal cord injuries
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
66/105
Monitoring Temperature
Hyperthermia Causes Malignant hyperthermia Endogenous pyroxenes (IL1) Excessive environmental warming Increases in metabolic rate secondary to:
Thyrotoxicosis Pheochromocytoma
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
67/105
Monitoring Temperature
Monitoring Sites Tympanic
Esophagus Rectum Nasopharynx
67
Normal values for a healthy adult undergoing
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
68/105
y g ganesthesia
Systolic Blood Pressure Diastolic Blood Pressure Heart Rate Respiratory Rate Oxygen sat. by oximetry End Tidal Carbon Dioxide tension Skin appearance Color Temperature Urine Production
SBPDBPHRRRSpO2ETCO2
85 16050 9550 1008 2095 10033 45warm, drypink36 37.5>= 0.5
mmHgmmHgbpmrpm%mmHg
O Cml.kg -1.min -1
Central Venous Pressure Pulmonary Artery Pressure Pulmonary Capillary Wedge Pressure Mixed venous oxygen saturation Cardiac OutputMean Arterial Pressure
*MAP = DBP + 1/3 ( SBP DBP )
CVPPAP (mean)PCWPSvO2COMAP
1 1010 205 15754.5 680 120
mmHgmmHgmmHg%1.Min -1
mmHg
68
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
69/105
THANKYOU69
Clinical measurement
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
70/105
Clinical measurement is limited by 4 major constraints:
1. Feasibility
2. Reliability
3. Interpretation
4. Value
4 mandatory steps in clinical measurement:
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
71/105
4 mandatory steps in clinical measurement:
Detection : sensing device ( biological signal : mechanical, electrical, electromagnetichemical or thermal energy)
Transduction : the output is converted into another form, usually to a
continuous electrical signal
Amplification and signal processing : - extract and magnify the relevant features of the signal and reduce unwanted noise
Display and Storage : the output of the instrument is presented to the operator
Mechanical versus Digital instruments
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
72/105
Mechanical versus Digital instruments
Mechanical instruments ;
- use the natural signal energy to drive a display,with minimal intermediateprocessing
Digital instruments
- non-electrical signals are converted by a transducer to an electrical signal suitablefor electronic processing by digital computers.
- higher accuracy and precision
Essential requiremets for CLINICAL MEASUREMENT
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
73/105
q
Accuracy is the difference between the measurements and the real biological
signal , or in practice, between a certain techique and a superior 'gold standardtechnique.
Precision describes the reproducibility of repeated measurements of the samebiological signal.
- calibration is important( against predetermined signals or for absolute measurements to zero)
MECHANICAL SIGNALS:
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
74/105
MEASUREMENT OF ARTERIAL PRESSURE
a wide range of instruments are used to measure pressure :
liquid column manometers : height, zero point, fluid density
mechanical pressure gauges : aneroid manometer
diafragm gauges (coupled to transducers)
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
75/105
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
76/105
Potential Methods To Measure Cardiac Output
Fick metdod Indicator dilution Pulse waveform ( pulse contour) methods ULTRASOUNDS ( 2D-Echo and Doppler techique) Bioimpedance
ANGIOGRAPHY MRI
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
77/105
Ideal Cardiac Output Monitoring Technique
Precise and No bias Non-invasive Continous and instantaneous Automatic Operator independent Cheap Easy available in the ICU Leads to treatment changes / improvement in outcome
IT DOES NOT EXIST !
Use the Best Compromise : feasibility precision patient !
The FICK principle
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
78/105
defines flow by the ratio of the uptake or clearance of a tracer within an organ tothe arterio-venous difference in concentration
CO = VO2 / [CaO2 CvO2])*100
V O2 per minute using a spirometer + Douglas bag CvO2 is taken from the pulmonary artery CaO2 a cannula in a peripheral artery
The FICK method
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
79/105
considered to be the most accurate method for CO
but : - invasive, time consuming- accurate VO2 samples are difficult to acquire
discontinous CO : Deltatrac (Datex)
continous CO : possible, but no integrated system available
modified Fick equation : continous CO by NICO2 apparatus
INDICATOR DILUTION
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
80/105
INDICATOR DILUTION
Chemical indicator dilution (dye)
Thermal indicator dilution
( Thermodilution )
the widest used : PAC = Swan Ganz
INDICATOR DILUTION
http://illuminations.nctm.org/imath/912/cardiac/student/images/catheterbig.jpg8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
81/105
CO measurement by indicator dilution has 3 phases :
(a) an indicator is brought into the circulation (injection)
(b) the indicator mixes with the bloodstream(mixing and dilution)
(c) the concentration of the indicator is measured downstream(detection).
Chemical indicator dilution
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
82/105
Chemical indicator dilution The Stewart-Hamilton formula (time-concentration curve)
using indocyanine green as indicator was the conventional indicator dilutionmethod used to measure CO in ICU until the 1970s.
Indocyanine green :- nontoxic, inert, safe- short half-life,- not affected by arterial saturation
The Thermodilution (TD) method
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
83/105
The Thermodilution (TD) method
Thermodilution = indicator is the change in blood temperature
An injectate of known volume and temperature is injected into the right
atrium and the cooled blood traverses a thermistor in a major vessel branchdownstream over a duration of time.
TD Methods :
1. PULMONARY Thermodilution (P-TD)
1. TRANSPULMONARY Thermodiution (TP-TD)
The CLINICAL STANDARD is the PAC !
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
84/105
Pulmonary -TD
PAC-Thermodilution
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
85/105
The change of the blood s temperature in is measured in the pulmonary arteryusing the PAC thermistor
The thermistor records the temperature change and the monitor electronicallydisplays a temperature/time curve.
The CO is inversely proportional to :- the temperature change- the area under the curve
( PAC measures the Pulm.CO = Global CO if no intracardiac shunt )
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
86/105
Sources of measurement error for P-TD
Loss of indicator Variation of injectate temperature and volume Recirculation - IC shunts : false high CO values Tricuspid regurgitation : false low CO values Fluctuations in baseline temperature
...........................
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
87/105
10 ml. cold optimal < 4 sec. > 4-5 sec. false low CO! at least 3 measurements and less than < 10 % between them
Advantages of P-TD
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
88/105
Advantages of P TD The standard method for clinical CO measurement
Simple and Repeated measurements possible.
The modified PAC may provide CCO- thermal indicator : intermitent heating of a resistace- 44C for 1-4 sec each 30-60 sec
- Not really continous : mean of 3-4 min ! - expensive
The PAC provides, in addition, PA pressures, PAOP, SvO2, and optionally,RVEF and RVEDV.
PULMONARY Thermodilution TRANSPULMONARY Thermodiution
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
89/105
PULMONARY Thermodilution TRANSPULMONARY Thermodiution
The pulmonary artery TD curve appears earlier and has a higher peak temperature thanthe femoral artery TD curve.
TP-TD is less invasive than P-TD, but does NOT give : SvO2 an PAP values !
,
The Clinical USE of TP-TD
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
90/105
The Clinical USE of TP-TD
Mainly : as a calibration method for othersystems : PiCCO, LiDCO-Pulse CO
PiCCO and LiDCO-Pulse CO are able after the initial calibration, tomeasure in a continous manner
( beat by beat ) the C.O, using :
the Pulse Contour method
The Pulse Contour method
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
91/105
1. CALIBRATED techniquesPiCCO
LiDCO Pulse CO
2. NON-CALIBRATED techniques
Flow-Track VIGILEONexfin
CCO by the pulse contour method
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
92/105
y p
The area under the systolic part of the AP waveform correlates :
- directly with Left Ventricular STROKE VOLUME- inversely with aortic impedance
For calibrated techiques : the Aortic impedance is estimated from AP and CO pre-measured values
( calibration : CO is ussualy measured by TP-TD)
SV
PiCCO
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
93/105
Continous pulse contour analysis with intermittent TP-TD calibration.
Enables continuous hemodynamic monitoring using:- femoral or axillary artery catheter
- central venous catheter
LiDCO Pulse CO
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
94/105
the independent calibration technique is : Lithium indicator Dilution
safe and minimally invasive : peripheral venous and arterial catheters
The PulseCO algorithm used by LiDCO is based on pulse power derivation.
Continuous, real-time cardiovascular monitoring
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
95/105
BIOIMPEDANCE
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
96/105
bio tissues (bone, muscle,blood, etc) have different electric proprieties blood is the most conductive tissue ( Na+ and Cl-)
pulsatile modification of ITBV TB TB ~ stroke volume
SV = K x (dZ / dt) / Zo x TEV
TB is measured by : producing and transmiting electricity ( high = 70 kHz low A = 2,5 mA ) betwwen 2 pairs of electrodes
E h di g h f i g th CO
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
97/105
Echocardiography for measuring the CO
2 D method
Doppler - method
Ultrasounds (1.)
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
98/105
US techniques can detect : the shape, size and movement of tissueinterfaces, especially soft tissues and blood (RBC)
US are defined by :- amplitude of oscillation (delta pressure : ambient to peak) dB- the wavelength (distance between successive peaks)
- frequency (inversely proportional to wavelength, nr. of cycles / second )
human ear can detect frequencies : 20-20,000 Hz. US have frequencies > 20,000 cycles /sec ( 20 KHz) diagnostic US uses frequencies in the range of 1-10 MHz.
Ultrasounds (2.)
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
99/105
Transducers :- generate and sense US- are made from ceramic materials able to transform mechanical energy (pressure) to
electrical energy and vice versa ( the piezoelectric effect )
- Transducers : generates ultrasound of the same frequency as the applied voltage
Shorter wavelengths and higher frequencies improve the resolution of distance,but tissue penetration is simultaneously reduced.
Amplitude determines the intensity of the ultrasound beam and therefore thesensitivity of the instrument.
2-D Method
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
100/105
Principle
Stroke volume= End diastolic volume End systolic volume
LV volumes estimated by Simpsons method, which is the summation ofthe volume of stacked cylinders within the LV at end-diastole and end-systole
150 ml - 52 ml= 98 ml
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
101/105
Doppler Effect - 3
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
102/105
pp Doppler effect represented by:
V = _ F . c _
2 F0 cos
Where V = velocity of objectF = frequency shiftc = speed of sound in medium (body tissue here)F0 = frequency of emitted sound
cos = angle between sound wave and flow (RBC)
cos 90 = 0 so the US beam should be parallel to RBC Maximum angle = 20
Doppler MethodPrinciple
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
103/105
Flow (stroke volume)=Area x Velocity
CO=Stroke volume * Heart rateArea of left ventricular outflow tractObtain LVOT dimension in parasternal long axis view
Simplified formula = (2.1cm) 2 * 0.785
D=2.1 cm
3 46 cm 2
Flow Velocity at LVOT Pulsed wave Doppler at LVOT in apical5 chamber view
Velocity time integral 25 cm
25 cm = 87 cm 3X OESOPHAGEAL DOPPLER
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
104/105
Measurement of blood flow velocity in the descending aorta atthe tip of the flexible probe
4 MHz continuous or 5 MHz pulsed wave
CO (cardiac output)SV (stroke volume)FTc (corrected f low time)PV (peak velocity)MD (minute distance)HR (heart rate)
THANKS for your attention !
8/10/2019 Curs 2012 Monitoring in Anesthesia.ppt
105/105
THANKS for your attention !