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DEPARTMENT OF ANESTHESIA
UNIVERSITY OF MANITOBA
Monitoring Training Module for
Para Professional Personnel
Preamble
The Department of Anesthesia at the University of Manitoba is committed to the
promotion of patient safety and quality of care. Education of providers of airway and
resuscitation support from all disciplines is a fundamental part of that mission. For this
educational effort to be effective, it is important to consider and incorporate the particular
needs of each group for whom skills development is contemplated. This document
outlines the structure, and goals and objectives of a program designed to meet the
developmental needs of paramedical personnel providing care for patients with respect to
monitoring physiologic well-being.
Program Outline
Each trainee will be provided with a program outline, including a reference manual,
orientation and contact information, and evaluation logs. At the end of the rotation, the
trainee will be expected to keep evaluation logs and provide them to the Coordinator of
the sponsoring program as proof of completion of the educational program.
The trainee will present to the assigned hospital OR suite on the first day of the rotation,
at the time and place indicated in the orientation manual. The senior resident or site
coordinator will direct the trainee to a primary staff person. This primary staffperson
shall
 Review the educational material with the trainee
 Provide resource discussion
 Evaluate the degree to which the trainee has met the knowledge objectives
 Record the results of that evaluation on the evaluation log
 Coordinate access to monitoring procedures with him/herself, enlisting other staff
as necessary and available
Each individual staff physician or resident who supervises airway management
techniques will
 Observe the trainee and provide formative feedback
 Evaluate the trainee’s competence with the technique
 Record the evaluation on the provided log
 As applicable review and evaluate elements of the curriculum as discussed with
the primary mentor
Goals and Objectives
By the end of this module, the trainee will be able to:
 Assess the presence and degree of cardiovascular instability by physical
examination
 Apply routine non-invasive monitors of cardiovascular integrity, including EKG
and non-invasive blood pressure monitoring
 Interpret the information from these monitors identifying
o The relevance of this information in context of information from other
sources
o The potential sources of error, and how to correct or allow for them
 Suggest appropriate additional monitoring of cardiovascular integrity including
urinary output and invasive arterial blood pressure monitoring, describing
o The relative advantages and disadvantages of adding that monitor
o The potential risks and complications
 Interpret the information from these monitors identifying
o The relevance of this information in context of information from other
sources
o The potential sources of error
 Assess the presence and degree of respiratory instability by physical examination
 Apply additional monitors of respiratory well-being, including Pulse oximetry,
airway pressure and flow measurement
 Describe the basic principles upon which each of the following monitors
functions
o EKG
o Non-invasive Blood pressure
o Oxygen saturation
Evaluation Log for Paramedical
Monitoring Training Module
Cognitive Objectives
EKG monitoring

Describes indications, contrainidications
and complications
 Correctly applies and sets up monitor
 Interprets for ischemia
 Identifies sources of error
NIBP monitoring
 Describes indications, contrainidications
and complications
 Correctly applies and sets up monitor
 Interprets for ischemia
 Identifies sources of error
Pulse Oximetry
 Describes indications, contrainidications
and complications
 Correctly applies and sets up monitor
 Interprets for ischemia
 Identifies sources of error
Technical Skills Objectives
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CARDIO-RESPIRATORY MONITORING IN ANESTHESIA
Roland DeBrouwere, MD, FRCPC
Of all the duties performed by the anesthesiologist perioperatively, none is more important
and more time consuming than monitoring of the cardio-respiratory system. When
anesthetics were first given 150 years ago, our professional ancestors had little to go by but
their own ability to observe the patient's colour and breathing while palpating the pulse for
rate and strength. Only in the twentieth century did devices to measure blood pressure and
to view the electrocardiogram come into existence. The new millennium should bring even
more exciting and exotic devices.
CARDIO-RESPIRATORY MONITORING – THE BASICS
Monitoring can be broadly broken down into two major categories: non-invasive and
invasive. As a general rule the more sophisticated monitors are more invasive and often
more expensive, require special skills and impose more risk to the patient. We therefore use
the less expensive and less risky monitoring routinely and save the more invasive monitors
for selected procedures and patients.
NON–INVASIVE MONITORS
1)
THE ANESTHESIOLOGIST
Anesthesiologists are trained to evaluate the cardio-respiratory system. Simple
techniques are used on every patient. These may seem like common sense but are
very important. These include:
1) Patient overall appearance.
2) Respiratory rate and depth – patency of the airway.
3) Skin colour – evidence of cyanosis, anaemia, poor peripheral perfusion.
4) Cerebral perfusion – alert, appropriate, confused, combative, comatose (this
modality is obviously lost under general anesthesia but is assessed
preoperatively in all patients).
These may sound like the ABC’s of resuscitation and in fact they are the simplest and
fastest way to assess the cardio-respiratory function of a patient. Next comes a more
detailed assessment and follows the traditional approach of inspection, palpation,
percussion and auscultation.
1) Peripheral pulses – presence/absence, rate, rhythm, quality
2) Cardiac auscultation - can be performed continuously with either a precordial or
esophageal stethoscope.
3) Respiratory auscultation – can also be performed continuously
One simple, yet highly valuable tool is the stethoscope. It can either be a precordial
head, taped to the left side of the patient's chest, or part of an esophageal probe
positioned so heart and breath sounds are well heard. By listening to the stethoscope,
frequency and effectiveness of ventilation can be determined, obstruction or
dislodgement of the airway or endotracheal tube can be detected and adventitial
sounds indicative of bronchospasm or pulmonary edema may be heard. Heart rate and
rhythm can be followed without constantly watching the ECG. A well position,
constantly monitored stethoscope is especially useful in pediatric, head and neck or
thoracic surgery where access to the patient may be very limited.
2)
THE BASIC NON-INVASIVE MONITORS
BLOOD PRESSURE:
Blood pressure is monitored in every patient in the operating room and is used along
with other monitors to assess overall cardiac function. Since PRESSURE = FLOW X
RESISTANCE, the presence of pressure indicates some flow and resistance is present
however it does not tell you the quantity of either. Flow, or cardiac output and
resistance (usually referred to as systemic vascular resistance) must be assessed by
other means. Blood pressure can be assessed manually with a cuff and stethoscope or
more commonly with an automatic machine set to cycle usually every three to five
minutes. Automated blood pressure devices free the anesthetist’s hands by measuring
systolic, diastolic and mean blood pressures at regular, pre-set intervals, displaying a
digital readout and many record the data. Patient movement (e.g. shivering) affects
them and awake patients often find them uncomfortable. Because of a longer inflation
time, nerve injury and limb ischemia has occasionally been implicated with these
devices.
ELECTROCARDIOGRAM:
Continuous monitoring of the electrical activity of the heart allows for ongoing
assessment of heart rate, rhythm and allows for real-time assessment of ST segments
to monitor for myocardial ischemia. Arrhythmias are extremely common during
anesthesia. Premature atrial or ventricular contractions or episodes of nodal rhythm
are frequent, but usually benign and self-limiting. Rarely, more serious arrhythmias
such as rapid supraventricular tachycardia or complex ventricular dysrhythmias may
require intervention. Any persistent arrhythmia should prompt a search for
underlying, life threatening problems such as hypoxemia, hypercarbia, acidosis or
ischemia. Coronary artery disease is often present in patients having non – cardiac
surgery. An imbalance between myocardial oxygen supply and demand may lead to
myocardial ischemia. The ECG is the best non-invasive perioperative monitor we
have available. Most electrocardiograms used in the O.R. utilize three limb leads
(positive, negative, and ground) which allow viewing one lead at a time in the screen
along with a digital display of the heart rate. Lead I, II or III can be continuously
monitored. Often Lead II is chosen as it gives the best visualization of p waves and
therefore rhythm assessment. The problem with only monitoring one lead at a time, is
that some problems may go undetected. PVC’s, which may look very abnormal on
one lead, may look almost normal on another. Ischemic changes are best seen on a
modified chest lead (CM5) but still if only this one lead is viewed a large percent of
such episodes may be missed. Simultaneous monitoring of more than one lead allows
better pick-up of abnormalities. Most monitors allow 5-lead capability with two
different leads viewed simultaneously. Also some machines continuously monitor
ST-segments for depression or elevation and can give a record of change over time.
PULSE OXIMETRY:
Adequate oxygenation and the ability to detect changes are critical during anesthesia.
Although direct observation of skin colour is helpful, it is quite subjective. Cyanosis
may be difficult to assess in anemic or dark skinned individuals. Pulse oximeters
provide an accurate, continuous non-invasive method of determining 02 saturation.
The pulse oximeter consists of a peripheral probe that can be clipped onto any finger,
toe or the ear lobe. One side of the probe shines two wavelengths of light through the
tissue. One wavelength corresponds to saturated, and the other to desaturated
hemoglobin. The other part of the probe picks up the light on the other side and, by
calculating the relative degree of absorption of the light, is able to quantify the percent
of saturated hemoglobin. Pulsatile flow is required. The oximeter will also measure
pulse rate. Though not quite instantaneous (a delay of a few seconds occurs before
changes are registered) the monitor rapidly shows changes in saturation. In many
units the tone of the signal corresponds to the saturation (a lower note equals lower
saturation) so it is possible to listen for changes without constantly viewing the screen.
The readout may be rendered inaccurate because of low flow states, movement,
electrocautery and the presence of abnormal hemoglobins.
VENTILATORY MONITORING:
End Tidal CO2 and Agent Monitors
A major cause of anesthetic morbidity and mortality is due to misplaced, displaced, or
disconnected endotracheal tubes. Methods for checking proper positioning of the tube
(seeing the tube pass between the cords, observing chest and abdominal movement,
auscultation) are very important, but not infallible, especially in obese patients. The
only definitive proof that a tube is endotracheal and not in the oesophagus is to detect
the presence of sustained CO2 in the expired gas, since of course only the lungs
produce CO2 - the stomach does not.
Though end tidal CO2 (ETCO2) units have been available for some time, only recently
have they become widely available. Most machines record inspired and expired CO2,
display the waveform on a screen, and measure respiratory rate. Using this device it is
possible to obtain a great deal of information.
There are basically two sources of information in the readout from a capnometer,
the number representing ETCO2, and the tracing, which is a continuous readout of
the CO2 at the level of the sampler over time. To derive useful information, one
must understand first where these signals come from.
The capnometer measures the CO2 at the aspiration point continuously. This is
usually placed at the end of an endotracheal tube. The capnograph is the resultant
trace, and is usually shaped as shown in Fig. 1.
40 mmHg
3
4
2
1
0 mmHg
Fig. 1
Phase 1, is comprised of inspiration, and early expiration. During inspiration, unless
the system is malfunctioning, the CO2 should be 0. During early expiration, the
patient is breathing out the anatomic dead space gas, which should be the same as
inspired (i.e. 0). Phase 2 begins when the mixed alveolar gas reaches the sampling
port later in expiration. Normal lungs empty at a relatively homogenous rate, and
so all the alveolar gas arrives as one front. As a result, the transition of Phase 1 to
Phase 2 is abrupt, going from baseline to the alveolar plateau in an almost vertical
step. Phase 3 is the alveolar plateau, which represents the mixed alveolar gas. This
should be constant, or very nearly so, and so Phase 3 is generally a straight line with
a slight upslope. Inspiration should bring another step change , which is phase 4,
back to Phase 1, to resume the cycle.
Abnormalities of the shape of any of these components can yield information,
independent of the actual ETCO2. If phase 1 is not flat, or not 0, there is a system
malfunction. If Phase 2 is a gentle upslope, instead of a rapid upstroke, there is
likely expiratory obstruction at some level. An upsloping Phase 3 is a somewhat
more sensitive indicator of expiratory obstruction. If Phase 3 is not flat, it likely
represents inspiratory efforts, or chest compressions. Finally, a slow descent in
Phase 4 suggests, expiratory obstruction.
The actual number means little in the absence of an understanding of what it is.
The ETCO2 is the last level of Phase 3 measured by the machine prior to the onset
of Phase 4. This should represent the mixed alveolar concentration (PACO2), which
should , in turn approximate the arterial concentration (PaCO2).
PaCO2  PACO2  ETCO2 (actual)  ETCO2 (measured)
There are several sources of error in this relationship. First of all, in the normal
patient, there is a small gradient between the PaCO2 and the PACO2. An increased
gradient will thus lower the ETCO2 reading relative to the PaCO2. This gradient
will increase with an elevated dead space (PE), severe V/Q mismatch (obstruction),
or increased Zone 1. Zone 1 increases when there is an increase in airway pressure
(obstruction tension pneumothorax, peep), or decreased pulmonary perfusion
pressure(cardiac output).
There can also be a difference between the PACO2 and the ETCO2. This would
occur when there is an upward slope to Phase 3 as in expiratory obstruction (see Fig
2). The upward slope occurs because lung units that empty and fill rapidly are
better ventilated and thus have a lower CO2. Progressively slower units have a
progressively higher CO2. The uppermost limit of this progression is the PaCO2,
since no alveolus can exceed this, even if completely unventilated. So the upward
slope one sees is actually the beginning of a hyperbolic curve with an asymptote at
CO2 = PaCO2. If the expiratory time were sufficient, the ETCO2 would be accurate,
but with significant obstruction and normal respiratory rates, the next inspiration
will intervene before the ETCO2 has had a chance to reach the top if its curve, and a
gap will result, with the ETCO2 therefore being measured too low.
PaCO2
ETCO2
Fig. 2
The final source of error is between the actual ETCO2 and that measured by the
machine. If there is introduction of a leak in the circuit anywhere from the sample
port to the measuring chamber, the sample will be diluted with air, and show a
falsely low ETCO2.
You will note that all these sources of error show the ETCO2 too low. That is
because the only CO2 in the equation should be coming form the patient. The only
way the ETCO2 can read falsely high is to either be inhaling CO2.
INVASIVE MONITORING
1)
ARTERIAL LINES
Placing a catheter directly into a peripheral artery and transducing the pressure to an
electrical signal displayed on a monitor allows for continuous accurate beat-to-beat
observation of the blood pressure, assessment of the pressure wave form, and can be
used for periodic removal of blood samples for blood gas analysis or other laboratory
tests. However, the procedure is invasive, painful to the patient and associated with
complications such as damage to the artery. Therefore, arterial lines are limited to
higher risk patients in whom continuous blood pressure determination is vital, or in
which frequent arterial sampling will be necessary.
2)
CVP AND SWAN GANZ CATHETER MONITORING
The patient who has an uncertain intravascular volume status, or in whom major fluid
shifts are expected, or when close monitoring of myocardial function is required; a
more invasive approach is required.
The purpose of central pressure measurement is to estimate the preload on the heart.
When we say “preload”, what we generally mean is left ventricular preload, since
we are usually trying to assess the state of the systemic vasculature, rather than the
pulmonary system. Strictly speaking, the preload is the length of the ventricular
muscle fibres prior to contraction. The volume of the ventricle is a much more
practical clinical measurement of preload, and is directly related to length. Single
measurements of volume can be readily obtained using echocardiography, but the
only useful continuous form of this is transesophageal (see below). It has not gained
widespread use outside of the OR because it requires considerable expertise and
cost, and is of little use in conscious patients. It is much easier to continuously
measure pressures than volumes, and thus it is the mainstay of invasive monitoring.
Using pressures to estimate the volume of the heart involves several assumptions.
The first, and most basic, is that the volume and pressure within the heart will be
directly proportional. This would be true if the compliance of the ventricle were
constant. Unfortunately, in real life, compliance differs not only between people,
but within the same heart over time. So, although there are normal ranges, pressures
are much more meaningful trended over time, and when correlated with clinical
observation.
The second set of assumptions has to do with which pressure is measured. The
pressure we are ultimately trying to estimate is the left ventricular end diastolic
pressure (LVEDP). To actually insert a catheter into the left ventricle is a very
invasive procedure, and upstream pressures are used, which generally correlate well
with it. Several other pressures may be chosen, but the further upstream, the more
potential there is for intervening pathology to alter the relationship. A more
exhaustive discussion of these pressures and their physiologic meaning is covered
in your basic cardiovascular series, but generally, it can be assumed that
CVP  RAP  PADP  PCWP  LAP  LVEPD
The easiest of these to measure is the CVP. A central venous pressure line (CVP)
can be inserted via a large peripheral vein (e.g. internal jugular, subclavian, femoral)
into the vena cava or right atrium and right heart filling pressures can be measured. A
low CVP indicates a relative hypovolemic state either due to hemorrhage, dehydration
or systemic vasodilatation. A high CVP may indicate fluid overload or a failing heart.
For more specific estimation of cardiac function a balloon flotation pulmonary artery
(Swan Ganz) catheter is useful. A "Swan" is a long catheter with a small balloon at
the distal tip which is inserted through a large bore CVP catheter, through the right
atrium, tricuspid valve, and right ventricle until the tip comes to lie in a branch of the
pulmonary artery. A proximal orifice located in the right atrium measures the RAP
and a distal orifice measures pulmonary artery pressure. When the distal balloon is
inflated the artery is blocked temporarily creating a static column of blood between the
catheter tip and the left atrium, allowing left sided pressures to be measured. The
resulting pressure is called the pulmonary capillary wedge pressure (PCWP) which
equals the left atrial end diastolic pressure (LAP pressure) which, if the mitral valve is
normal, equals left ventricular end diastolic pressure (LVEDP). A rising LVEDP
suggests myocardial dysfunction.
By injecting cool saline through the catheter, thermistors measure temperature change
as the fluid bolus circulates and cardiac output is calculated. From this, cardiac index,
systemic and pulmonary vascular resistance, and portions of the right and left
ventricular function curves can be deduced.
These invasive techniques are not free of complications and the risk/benefit ratio must
be considered before subjecting a patient to them. When inserting a CVP, damage to
the vein or adjacent artery can occur. Attempts to cannulate the subclavian or internal
jugular veins may lead to a pneumothorax if the pleura are punctured. Inflation of the
balloon on a Swan Ganz may rupture the pulmonary artery, and passage often causes
arrhythmias.
TRANSESOPHAGEAL ECHOCARDIOGRAPHY
This modality is not only used for diagnosis but can also be used for real-time
monitoring of cardiac function. An ultrasound transducer is passed through the oropharynx
into the esophagus and stomach and the pericardium, cardiac chambers and valves and great
vessels can be visualized. This monitor was once isolated to patients undergoing cardiac
procedures. More and more it is being utilized in the perioperative period in high-risk
patients having a variety of non-cardiac procedures. There is a remote risk of esophageal or
gastric trauma or perforation with insertion of the probe and expertise is required in
positioning and interpretation of the ultrasound images.
CONCLUSION
In conclusion from the "finger on the pulse" days, anesthesia has evolved into a
technologically very advanced specialty allowing us to monitor continually many
physiologic parameters. The rewards of this has been increased patient safety when the
equipment is used properly and conscientiously and when appropriate action is taken when a
problem is detected.