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The Catheterization Laboratory 15
5. Mouth or jaw irregularities or deformities, including loose or
capped teeth or dentures
American Society of Anesthesiologists
Physical Status Classification
The American Society of Anesthesiologists Physical Status Classification (Table 1-5) is helpful in determining the patient’s eligibility for
conscious sedation. It uses a 1 to 5 classification range, with 1 being
a healthy patient and 5 being a moribund patient. Procedural sedation
is appropriate for patients in classes 1, 2, and 3. Patients in classes 4
and higher are better suited for general anesthesia. There are several
contraindications to conscious sedation that include the following:
1. Recent (<2 hour) ingestion of large food or fluid volumes
2. A physical class 4 or greater
3. A lack of support staff or monitoring equipment
4. A lack of experience/credentialing on the part of the clinician
Monitoring Parameters
Level of Consciousness. The patient’s level of consciousness should
be assessed often before and during the procedure. The level of consciousness can be assessed by the patient’s response to verbal commands or to light tactile stimulation. Once aroused, the patient should
respond appropriately to verbal commands. The nurse or operator can
assess this easily by periodically talking to the patient and listening to
his or her response. When the patient’s only response is reflex withdrawal from painful stimuli, deep sedation is evident, and special care
must be taken to ensure patency of the air way, proper ventilation, and
hemodynamic stability.
Pulmona ry Ventilation. Pulmonary ventilation can be monitored
by the observation of spontaneous respiratory activity or, when possible, auscultation of breath sounds. During certain invasive procedures, direct monitoring of the respiratory rate is often difficult because
of sterile drapes and equipment.
Oxygenation. Continuous assessment of the patient’s blood oxygen
saturation by pulse oximetry should be a part of any conscious sedation monitoring and assessment protocol. This monitor is only a tool
and not a replacement for direct observation of the patient. There can
Table 1-5
American Society of Anesthesiologists Physical
Status Classification
Class Description
1 A healthy patient (e.g., varicose veins in an otherwise healthy
2 A patient with mild systemic disease that in no way inter feres
3 A patient with severe systemic disease that is not
4 A patient with severe systemic disease that is a constant
5 A moribund patient who is not expected to survive for 24 hours
patient)
with normal activity (e.g., controlled hypertension, controlled
diabetes, chronic bronchitis)
incapacitating (e.g., insulin-dependent diabetes, angina,
pulmonary insufficiency)
threat to life (e.g., cardiac failure, major organ insufficiency)
with or without surgery (e.g., intracranial hemorrhage in
coma)
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The Catheterization Laboratory
be a 1-minute delay between the onset of hypoxia and the decrease
in the monitor reading.
End-tidal carbon dioxide monitoring measures exhaled carbon
dioxide and is most commonly used in intubated patients receiving
mechanical ventilation, but it is also used in nonintubated patients
undergoing moderate or deep sedation. The measurement of end-tidal
carbon dioxide (E
), called capnography, is useful as an adjunct to
tCO2
other monitoring methods in detecting hypoventilation before pulse
oximetry indicates oxygen desaturation. It is a more sensitive gauge
of hypoventilation than visual observation. In procedural sedation,
side stream capnography equipment usually consists of sampling
probes to measure gases from the nose and sometimes the mouth.
Additional oxygen can be administered through the same cannula.
The Practice Guidelines for Sedation and Analgesia by NonAnesthesiologists published by the American Society of Anesthesiologists (ASA) outlines the following areas for patient monitoring during
moderate or deep sedation states: “During moderate or deep sedation,
the adequacy of ventilation shall be evaluated by continual observation
of qualitative clinical signs and monitoring for the presence of exhaled
carbon dioxide unless precluded or invalidated by the nature of the
patient, procedure, or equipment.” The ASA amended its Standards for
Basic Anesthetic Monitoring to include mandatory exhaled dioxide
E
monitoring during both moderate and deep sedation to its exist-
tCO2
ing requirement.
2
Sedative agents may cause arrhythmias and hypotension.
Although continuous ECG monitoring is performed during preprocedural patient preparations, blood pressure should also be monitored
often at 1- to 2-minute intervals during the onset of sedation and 5- to
10-minute intervals during the procedure. Hemodynamics should
return to baseline before discharge.
The Aldrete Scoring System (Table 1-6) can be used to assess the
effects of sedation on the patient’s major systems (neurologic, respiratory, and circulatory). A score of 0, 1, or 2 is given for level of activity,
level of consciousness, respiratory ability, blood pressure, and color.
Drugs for Conscious Sedation
First-line drugs and dosages for conscious sedation are listed in
Table 1-7.
Postprocedure Monitoring and
Discharge Criteria
Patients who receive conscious sedation should be monitored for 1 to
2 hours before discharge. During this time the patient should be
assessed and monitored with the same parameters used in the preprocedural assessment. When the patient returns to baseline, discharge
is appropriate. The following discharge criteria should be met before
the patient is sent back to the floor or home:
1. The Aldrete score has returned to baseline (summed Aldrete scores
of 9 or 10).
2. At least 2 hours have elapsed since the last dose of sedative agents.
3. Vital signs have returned to baseline.
4. Ventilation (respiratory rate and oxygen saturation) has returned to
baseline.
5. The patient is mentally alert, and all protective reflexes are
intact.
Outpatients who are being discharged to home should be able to
ambulate appropriately for their age and condition. An escort should
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The Catheterization Laboratory 17
Failure to elicit response Frank cyanosis
Fully alert and answers questions Normal pink
Arousable Pale, dusky, blotchy
BP ± 20% of baseline
BP ±20% to 50% of baseline
BP >50% of baseline
Aldrete Scoring System
Score Activity Respiration Circulation Consciousness Color
2 Able to move four extremities Able to breathe deeply and cough
1 Able to move two extremities Limited respirator y ef fort (dyspnea)
Table 1-6
0 Not able to control any extremities No spontaneous respirator y ef fort
BP, Blood pressure.
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Table 1-7
The Catheterization Laboratory
First-Line Drugs for Conscious Sedation
Drug Dose Max
Morphine (narcotic
analgesic)
Meperidine (narcotic
analgesic)
Fentanyl (narcotic
analgesic)
Midazolam (sedative,
amnesic)
1-2 mg 10 mg or
10-20 mg 100 mg or
25 µg 200 µg or
0.5-1.0 mg 5 -10 mg or
Onset
(min)
0.15 mg /kg
1.5 mg/kg
3 µg/kg
0.1 mg /kg
Duration
(min)
1-2 30- 60
1-2 20- 40
1 10-15
1-3 15-30
be available, and the patient should be instructed about not driving a
motor vehicle for an appropriate period.
Postcatheterization Check-Up
The operator should check on the patient several hours after the procedure. Vital signs should be normal. Low blood pressure is usually
due to diuresis and responds to normal saline. Tachycardia with low
blood pressure indicates blood loss until proven otherwise. The arterial access site should be checked for pain and hematoma. The operator should check the groin site and distal pulses in legs or the wrist for
loss of pulse. Urine output should be >
reflect unsatisfactory volume replacement or early onset of contrastinduced renal failure. A cool or painful extremity requires immediate
assessment to determine whether thrombus, spasm, or vasoconstriction is responsible for arterial occlusion. Limb ischemia including the
arm for radial cases or an enlarging hematoma requires urgent consultation with a vascular surgeon, repeat angiography, and at times an
urgent return to the catheterization laboratory.
30 mL/hr. Low urine output may
Angiogram Review
To provide the patient and family with an understanding of the coronary artery disease or other findings, a preliminary schematic diagram
of the heart and coronary arteries can be provided. A similar diagram
should be put in the chart to help others understand the findings. A
catheterization instruction book is helpful and may contain a blank
standard diagram (Fig. 1-4). The booklet explains the catheterization
procedure and the possible meaning of various findings on the coronary angiogram. In some cases, reviewing the actual coronary cineangiograms with the patient and family members may be helpful. After
discharge the patient may wish to see the angiograms to understand
the disease better and to ask questions and receive answers specifically with regard to future treatment (after the operator discusses the
findings and plans with the referring or primary care physician).
Taking the time to explain the findings by referring directly to the
diagram or cineangiographic film is rewarding. “No one ever took time
to explain my heart problem this way, and now I understand what is
wrong” is a frequent comment. The risk of a patient becoming alarmed
or depressed after viewing the cineangiogram has not been borne out
by experience with thousands of patients and their families. The additional burden of taking the time to show the angiograms to the patient
is worth the effort. In some busy laboratories, this approach may not
be feasible, but with images on disks, almost every laboratory has an
open computer to share the angiograms with the patient. The operator
should always discuss the findings and possible recommendations
with the primary physician first because catheterization is principally
a consultative service.
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The Catheterization Laboratory 19
A
Figure 1- 4
contact information of practitioner is included. B, Details of angiogram is
drawn on figure. (Reprinted with permission from the Cath Lab Digest.
Copyright HMP Communications.)
Diagram for patient after cardiac catheterization. A, Name and
B
Special Preparations for Cardiac
Catheterization
Table 1-8 lists conditions that require special preparations.
Table 1-8
Conditions Requiring Special Preparations
Condition Management
1. Allergy
a. Prior contrast studies
b. Iodine, fish
c. Premedication allerg y
d. Lidocaine
2. Patients receiving anticoagulation
(INR >1.5)
3. Diabetes
a. NPH insulin (protamine
reaction)
b. Renal function (prone to
contrast-induced renal failure)
c. Metformin usage
4. Electrolyte imbalance (K+, Mg2+)
5. Arrhythmias 5. Defer procedure, administer
6. Anemia 6. Defer procedure
7. Dehydration 7. Hydr ation
8. Renal failure 8. Limit contrast
INR, International normalized r atio; NPH, neutral protamine Hagedor n.
1. Allergy
a. Contrast premedication
b. Contrast reaction algorithm
c. Hold premedication
d. Use Marcaine (1 mg/mL)
2. Defer procedure
a. Vitamin K+, 10 mEq/hr
b. Fresh frozen plasma
c. Hold heparin
d. Protamine for heparin
3. Hydration to increase urine
output >50 mL/hr; met formin
held 48 hours; if renal
insufficiency, postpone
catheterization and consider
urgency and risks of lactic
acidosis
4. Defer procedure, replenish or
correct electrolytes
antiarrhythmics
a. Control bleeding
b. Transfuse
a. Maintain high urine output
b. Hydrate
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The Catheterization Laboratory
Contrast Media Reactions
The Committee on Safety of Contrast Media of the International Society
of Radiology reported that in more than 300,000 patients the overall
incidence of adverse reaction was 5% or less. Adverse reactions were
found in 10% to 12% of patients with a history of allergy and in 15% of
patients with reported reaction on previous x-ray examination. From
these reports, major reactions do not tend to recur on reexamination,
whereas minor reactions are more likely to be repeated. There are
three types of contrast allergies (Box 1-4): (1) cutaneous and mucosal
manifestations, (2) smooth muscle and minor anaphylactoid
responses, and (3) cardiovascular and major anaphylactoid responses.
Management of contrast reactions is summarized in Table 1-9.
Major reactions involving laryngeal or pulmonar y edema are
often accompanied by minor, or less severe, reactions. Although some
reactions to a pretest contrast dose may be violent (but rarely life
threatening), pretesting has been found to be of no value in determining who will have an adverse reaction.
Full emergency resuscitation equipment and a trained team
should always be available for any patient receiving contrast media.
Nonionic, low-osmolar ionic, or iso-osmolar contrast media have
replaced ionic high-osmolar contrast media to minimize the chance
of adverse contrast-media-related events (e.g., allergic reaction or
contrast-induced nephropathy).
Patients reporting allergic reactions to contrast media should be
premedicated with prednisone and diphenhydramine (Benadryl). The
routine for the laboratory may var y, but common dosages include
Box 1-4 Anaphylactoid Reactions to Contrast Medium
Cutaneous and Mucosal
Angioedema
Flushing
Laryngeal edema
Pruritus
Urticaria
Smooth Muscle
Bronchospasm
Gastrointestinal spasm
Uterine contraction
Cardiovascular
Arrhy thmia
Hypotension (shock)
Vasodilation
Table 1-9
Anaphylactoid Reaction Prophylaxis for Emergency
Percutaneous Coronary Intervention
Medication Dosage Route Mechanism
Standard Agents
Methylprednisolone or
Dexamethasone or
Solu-Cor tef
Cimetidine
Benadr yl
Modified from Klein LW, S heldon MW, Brinker J, et al: The use of r adiogr aphic
contrast media during PCI: a focused review. A position statement of the Society of
Cardiovascular Angiography and Inter ventions. Cath Cardiovasc Inter vent 74:728–
746, 2009.
80-125 mg IV Antiinflammator y
16 mg IV Antiinflammator y
100 mg IV Antiinflammator y
300 mg IV H2 blockage
25-50 mg IV or PO H1 blockage
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The Catheterization Laboratory 21
60 mg of prednisone the night before and 60 mg of prednisone the
morning of the procedure, along with 50 mg of oral Benadryl given at
the time of call to the catheterization laboratory. Pretreatment with
corticosteroids to alleviate reactions to IV contrast media has been
found to be helpful in reducing all types of reactions except those
characterized predominantly by hives. Premedication may not completely prevent the occurrence of adverse reactions. Routine treatment
of patients with prior allergic reactions with an H
blocker (e.g., cimeti-
2
dine) does not appear to have any benefit. Patients with known prior
anaphylactoid reactions to contrast dye should be pretreated with steroids and an H
blocker.
2
Protamine Reactions
Although protamine is used widely for reversing systemic heparinization after cardiac catheterization, major reactions simulating anaphylaxis can occur, albeit rarely. Minor protamine reactions may appear
as back and flank pain or flushing with peripheral vasodilation and
low blood pressure. Major reactions involve marked facial flushing
and vasomotor collapse, which may be fatal. Patients taking NPH
insulin have an increased sensitivity to protamine. The incidence of
major protamine reactions in NPH insulin-dependent diabetics is 27%
compared with 0.5% in patients with no history of insulin use. Diabetic
patients receiving NPH insulin and patients with allergies to fish
should not be given protamine after cardiac catheterization. If use of
protamine is necessary for these patients, it should be administered
cautiously in anticipation of a major reaction.
Contrast-Induced Renal Failure
(Contrast-Induced Nephropathy)
Patients with diabetes or renal insufficiency or patients who are dehydrated from any cause are at risk for contrast-induced renal failure.
Advance preparations to limit contrast-induced renal failure include
hydration and maintenance of large-volume urine flow (≥
These patients should be hydrated intravenously the night before the
procedure. After the catheterization procedure, IV fluids should be
continued liberally unless intravascular volume overload is a problem.
Furosemide (Lasix), mannitol, and calcium channel blockers are not
helpful in reducing contrast-induced renal failure (Box 1-5). In the
Box 1-5 Pharmacologic Prophylaxis for Contrast-Induced
Nephropathy
Detrimental
Furosemide
Mannitol
Endothelin receptor antagonist
Ineffective
Fenoldopam
Dopamine
Calcium channel blockers
Atrial natriuretic peptide
L-Arginine
Merits Further Study
Theophylline
Statins
Ascorbic acid
Prostaglandin E
1
200 mL/hr).
Modified from St acul F, Adam A , Be cker CR, et al: Strategies to reduce the risk of
contrast-induced nephropathy. A m J Cardiol 98(suppl):59K–77K, 2006.
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recovery area and medical floor, the patient’s urine output should be
monitored. If output falls and is not responsive to increased IV fluids,
renal insufficiency should be suspected. A consultation with a nephrologist may be helpful. Nonionic or low-osmolar contrast agents have a
lower incidence of contrast-induced nephropathy than ionic agents.
The Catheterization Laboratory
Insulin-Dependent Diabetic Patients
For patients taking subcutaneous insulin (NPH, regular), an overnight
fast with their normal dose of insulin could cause hypoglycemia. The
dose of NPH insulin should be decreased by 50% for patients coming
to the catheterization laboratory when they are NPO in the early
morning. Recall that patients receiving NPH insulin are at higher risk
for protamine reactions.
Diabetic Patients Using Metformin
Metformin (Glucophage) is an analog of phenformin, an oral antihyperglycemic agent that was withdrawn from the market because of the
risk of lactic acidosis. Rare cases of metformin-associated lactic acidosis have been reported in diabetic patients with chronic renal insufficiency. Contraindications and precautions in the product literature
state the following:
Parenteral contrast studies with iodinated materials can lead to acute
renal failure and have been associated with lactic acidosis in patients
receiving Glucophage. Therefore in patients in whom any such study
is planned, Glucophage should be withheld for at least 48 hours
before and 48 hours subsequent to the procedure and reinstituted
only after renal function has been reevaluated and found to be
normal.
Metformin is contraindicated in patients with renal dysfunction,
as determined by elevated serum creatinine levels. There is no evidence that withholding metformin for 48 hours before a contrast procedure in patients with normal renal function provides any clinical
benefit.
Guidelines for Use of Metformin and Iodinated
Contrast Material (Adopted from the University
of Kentucky)
A. Elective procedures
1. If renal function is normal (serum creatinine <1.5 mg/dL), con-
trast material may be administered parenterally without discontinuing metformin before the study. The patient should be
hydrated.
2. After the study, the patient should consult with his or her physician before resuming metformin. In most cases, the patient may
resume metformin after 48 hours unless there is evidence of
acute renal failure or the patient is at high risk for renal failure
related to the following:
a. Low cardiac output
b. Hypovolemia
c. Contrast administration (<72 hours) or excess contrast load
>3 mg/kg
d. Cyclosporine therapy
3. If renal function is abnormal (serum creatinine ≥1.5 mg/dL), the
contrast study should be postponed for patients who have
received metformin within 48 hours.
B. Emergency procedures
1. If renal function is normal, the study may proceed as with elective procedures.
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2. If renal function is abnormal, the relative risks versus benefits
must be considered and the following precautions taken:
a. Discontinue metformin.
b. Hydrate the patient during and after the procedure (IV saline
1 mL/kg/hr).
c. Increase urine output (if possible).
d. Minimize the volume of low-osmolality contrast material.
e. Monitor renal function closely after the procedure.
f. If acute renal failure occurs after the procedure, do not resume
metformin.
g. Monitor the patient for signs of lactic acidosis (e.g., abdominal
pain, obtundation, hypotension, hypercapnia) when metfor-
min is resumed. Arterial blood gas analysis and measure-
ment of plasma lactate, glucose, and ketones (including
β-hydroxybutyrate dehydrogenase) confirm the diagnosis.
Early hemodialysis may be needed.
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The Catheterization Laboratory 23
Team Approach to
Cardiac Catheterization
Physician Viewpoint
A new person in the cardiac catheterization laboratory should observe
the variety of catheterization procedures for at least 10 consecutive
cases. This observation period gives the new member of the catheterization team a chance to appreciate the timing, rhythm, and recurrent
steps that are required of each member as an integral part of the laboratory. Each laboratory has an individual routine that may vary among
operators. No one laboratory routine is best, but learning the routine
and joining the team smoothly are important first steps.
The new operator-in-training learns that the attending physician
is ultimately responsible for all aspects of the procedure and must
check each step of the procedure to ensure accuracy and safety.
A similar approach can be recommended for new nurses and
technicians.
Learning the “Routine” Overview
1. The patient is seen by a member of the cardiac catheterization
team, indications for the procedure are discussed, risks are
explained, consent is obtained, special preparations are made, and
orders and chart notes are written.
2. The patient arrives in the laboratory, greeted by the nurses, moved
from a holding area into the angiographic suite, and prepared and
draped in a sterile fashion. The physician may or may not participate with the nurses in the draping.
3. Arterial and venous access is obtained depending on the patient’s
clinical problem and the routine of the laboratory.
4. Right-sided heart catheterization, coronar y angiography, and left-
sided ventriculography are performed as indicated by the clinical
situation with the appropriate hemodynamic and angiographic
measurements. PCI may proceed ad hoc if the patient has consented in advance.
5. At the conclusion of data collection, angiographic study, and pos-
sible intervention, the catheters are removed.
6. For femoral access procedures, hemostasis may be obtained in
the lab with a vascular closure device (VCD). Alternatively, the
patient may be transferred to the holding area where the sheath is
pulled, and hemostasis is obtained with manual compression. The
patient is returned to his or her room. For 5-F to 6-F femoral sheaths,
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7. Several hours after the procedure, a member of the catheterization
8. Preparations for discharge (that day or the following morning) or
The Catheterization Laboratory
recovery usually requires 4 hours or more of bed rest. For procedures using sheaths of 5 F or less or procedures in which hemostasis is obtained with a VCD, 1 to 2 hours of bed rest with 4 hours of
observation before discharge is usually sufficient. For radial artery
access and hemostasis, the patient can sit in a reclining chair and
after premedication has worn off can be discharged (usually within
2 to 3 hours).
team checks the patient’s arterial access site(s), identifies (and
treats) any problems that may have occurred, and presents the
preliminary findings again to the patient and family after discussion
with the referring physician. Unless the operator is also the primary
care physician, the catheterization team should discuss results and
management options with the patient’s primary care physician
before taking the patient’s treatment into their own hands.
for further procedures are made after the cardiac catheterization data have been reviewed by the attending and referring
physicians.
Nurse and Technician Viewpoint—The
Catheterization Team
The composition of a catheterization team varies among laboratories.
The smallest functioning unit would consist of a physician, an assisting
physician or nurse, a nurse circulator or recording technician assigned
to the laboratory, and a nurse outside the laboratory able to assist. For
more specialized procedures, the team is increased appropriately.
Personnel are trained specifically to provide technical support
necessary for the safe performance of cardiac catheterization procedures. Several disciplines are called on to provide this support.
Each member of the team assumes an important role during the
procedure.
Personnel and Functions
1. A circulating nurse or technologist must be capable of assisting the
physician in all aspects of care of the patient, including routine
cardiovascular emergency care.
2. A scrub nurse or technologist is needed at the x-ray table to assist
the operating physician with all equipment and supplies used in
catheterization. This person assists in the exchanging of catheters
and other specialized maneuvers.
3. A radiologic technologist is trained in x-ray principles related
to cardiovascular procedures, cineangiography, fluoroscopy, and
the use of power contrast injectors and digital cineangiographic
imaging systems.
4. A monitoring and recording technologist is responsible for monitor-
ing and recording the ECG and hemodynamic data and keeping
the physician apprised of changes in cardiac pressures and
rhythms. The technician must be able to interpret pressure and ECG
waveforms and operate all physiologic recording equipment.
Rule for Success: Communication in the
Catheterization Laboratory
Communication among team members is critical. Communication at
the beginning of the day with team members will improve efficiency.
Keeping the physician informed as to the status of his or her procedure
will enhance his or her ability to manage time and minimize delays
in arriving to the laboratory. Likewise, communication from the
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