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| Dr. Marc Kalinowski attended
Medical School at the University of
Giessen and trained in the
Department of Diagnostic Radiology
at the University of Tübingen from
1996–1998. Since 1998, he has
been a Fellow in the Department of
Diagnostic Radiology at the
Philipps-University of Marburg. He
received Board certification in
Diagnostic Radiology in 2005.
Dr. Kalinowski’s research focus is
interventional radiology, in
particular experimental research on
restenosis following percutaneous
transluminal angioplasty. He has
also carries out research on
alternative contrast agents for
computed tomography and
angiography. |
Sedation and pain management in interventional radiology
Marc Kalinowski and
Hans-Joachim Wagner
Department of Diagnostic Radiology, Philipps-University
Hospital, Marburg, Germany
Address for correspondence:
Marc Kalinowski, MD
Department of Diagnostic Radiology
Philipps-University Hospital
Baldingerstrasse
35033 Marburg, Germany
Tel: +49-6421-286-6231 Fax: +49-6421-286-7066
Email: kalinows@med.uni-marburg.de
Abstract
Administration of sedation and analgesia in
interventional radiology is often necessary during
painful diagnostic and therapeutic procedures and
must be safe and comfortable for the patient. Nonanaesthesiologists
performing sedation should be fully
trained in the pharmacology of these medications, the
physiology of sedation and analgesia, the monitoring of
patients, airway support, ventilatory care, early and
appropriate management of complications, and
cardiopulmonary resuscitation. Although these agents
are generally safe, catastrophic complications related to
their use can occur, often as a result of incorrect drug
administration or inadequate patient monitoring. Good
sedation practice involves pre-sedation assessment and
optimal selection of patients, careful monitoring and
support from dedicated trained personnel in high-risk
patients and adherence to recovery and discharge criteria.
Introduction
Interventional radiological procedures have increased
during the past decades in number, complexity and
importance. They have been valued by clinicians and
patients because of their minimally invasive character
and as an alternative to major surgical procedures.
Nevertheless, as the patient is awake during the
majority of these interventions, it is important that
they feel the least possible distress. Apart from
producing pain and discomfort, these procedures can
also invoke fear and anxiety reactions,1 rendering
patients unable to follow breathing and movement
instructions. Furthermore, increased sympathetic
activity with tachycardia and hypertension has the
potential to precipitate myocardial ischaemia or
infarction in susceptible patients.2 Patients undergoing
these interventions often require sedation and analgesia
to enhance procedural safety, comfort and success.
The recent proliferation of these procedures has
increased the demand for sedation and analgesia.
Proper use of analgesic and/or sedative agents improves patient satisfaction, reduces procedure times and
stabilises haemodynamic status. However, sedation
carries significant risks for the patient, especially when
inappropriate techniques are used by inexperienced or
untrained personnel.3 Although anaesthesiologists are
best equipped to administer sedation and analgesia,
they are not usually available to attend all interventional
radiological procedures. As non-anaesthesiologists are
increasingly involved in sedation,4,5 it is crucial for them
to understand safety considerations and to receive
proper training.
This article will review the use of sedation and analgesia
in interventional radiology, describe the different
available pharmaceutical agents and outline factors
affecting the safety of procedural sedation, including
the performance and management of sedation and
analgesia. The recommendations included in this review
are primarily derived from practice guidelines outlined
by the American Society of Anesthesiologists (ASA) task
force on sedation and analgesia by non-anaesthesiologists
and other guidelines published in medical literature.6
Definitions
Sedation refers to the use of pharmacological or
non-pharmacological means to depress the central
nervous system and reduce patient anxiety and
irritability. Proper sedation achieves anxiolysis and in
some circumstances, amnesia. The stages of sedation
have been categorised in an attempt to define targeted
endpoints for drug administration. However, the depth
of sedation is not easily divided into stages but rather
refers to a therapeutic continuum ranging from minimal
anxiolysis to coma.6
The term ‘conscious sedation’ continues to be used in
medical literature. However, this term is no longer
included in the ASA Standards and its use should be
avoided because it is imprecise and potentially
misleading.7 Instead, the term ‘moderate sedation’
should be used. Moderate sedation is defined as a minimally depressed level of consciousness that retains
the patient’s ability to independently and continuously
maintain airway patency and respond appropriately to
physical stimulation or verbal commands. It is
produced by a pharmacological or non-pharmacological
method or a combination of these (see Table 1).
 |
| Table 1. Definitions of levels of sedation adapted from guidelines for
sedation and analgesia by non-anaesthesiologists |
The difference between analgesia and conscious
sedation is the intent.With conscious sedation, the
intention is to produce an altered mental state as
opposed to analgesia. Sedation and analgesia are
distinct processes: some patients require primarily
sedation, some primarily analgesia provided by opioids
or local anaesthetic agents, and some both of them.
Painful procedures often require both sedation and
analgesia because sedation alone in the presence of
pain may cause confusion and restlessness. Non-painful
procedures in uncooperative patients may require
sedation alone. Drugs and techniques should be
selected on a case-by-case basis according to the effect
desired, procedural requirements and the needs of the
individual patient.8 Medication should be administered
in an attempt to achieve the following goals:
• To provide adequate analgesia, sedation, anxiolysis
and amnesia during the procedure.
• To control unwanted motor behaviour that inhibits
the performance of the procedure.
• To rapidly return the patient to a state of
consciousness.
• To minimise the risk of adverse events related to
the procedure.
The pharmacological profile of the most commonly
used drugs for the administration of sedation and
analgesia is summarised in Table 2. The lower end of the
dose range should be used initially to cater for
inter-patient differences.
 |
| Table 2.Medications commonly used for sedation |
Sedative dosage needs to be decreased in the elderly
or sick patient and in those with organ dysfunction,
highlighting the importance of pre-sedation
assessment. For non-anaesthesiologists, a stepwise
protocol should be used defining the initial, incremental
and maximum dosage found to be safe and effective.9,10
Pharmaceutical agents
Hypnotics and sedative drugs
Benzodiazepines produce a dose-related CNS
depression. They cause anxiolysis, antegrade amnesia, hypnosis and have an anticonvulsive effect. They have
no analgesic effects and, for this reason, they should be
combined with opioids when analgesia is required in
addition to sedation. The most commonly used
benzodiazepines for sedation are midazolam and
diazepam. Their short-acting sedative effects combined
with rapid recovery and low risk of respiratory
depression makes these drugs the favoured sedative
agents for use by non-anaesthesiologists.5,9
Hypnotic drugs like propofol and ketamine are
intravenous general induction anaesthetic agents.
At sub-hypnotic doses, these have good sedative and
antiemetic properties. Propofol has no analgesic effects
and is often combined with opioids, such as fentanyl.
Propofol can rapidly cause apnoea even in low sedative
doses and consequently current guidelines recommend
that propofol only be used under supervision of an
anaesthesiologist.11 However, it has been shown that
titrated doses of propofol can be used for effective
sedation during interventional radiological procedures
without inducing hypoxaemia or hypercapnia.5
Miscellaneous
Nitrous oxide has good analgesic effects and may be
useful for short duration procedures. However, it must
be used in well-ventilated rooms to avoid affecting the
operator. Inappropriate use can lead to severe
hypoxaemia and the risk of aspiration12
Chloral hydrate has long been used for paediatric
sedation, although it has a long duration of action
and residual effects are common. Motor imbalance,
agitation and restlessness can occur after the patient is
discharged home. Use is now restricted to children
younger than 3 years of age.13
Other drugs like methohexital, thiopental and
etomidate are potent drugs for inducing general
anaesthesia. Their use by non-anaesthesiologists is not
recommended.
Analgesics
Opioids are potent analgesics and have a sedative effect,
but may cause dysphoria, nausea, vomiting and
respiratory depression. These adverse effects limit their
use to painful procedures in which analgesia is required.
Fentanyl is a short-acting opioid and small doses may
reduce the required doses of sedatives. Fentanyl is
favoured over other opioids because of its rapid onset
and suitable duration of action. Sufentanil is a shortacting
opioid that is eight-to-ten times more potent
than fentanyl with a similar onset of effect. Remifentanil
is a new opioid with a rapid onset which is administered
by an infusion, titrated to the desired effect. Morphine is
a long-acting opiate that is a sedative, anxiolytic and
analgesic. Because of its longer duration of action, it is
less suitable than a titratable and reversible agent.14,15
Reversal agents
These agents should be given in increments, waiting at
least 1–2 minutes between each dose. Their use should
be reserved for instances in which patients have
inadvertently been sedated more deeply than was
intended. Naloxone is an opioid reversal agent that reverses
respiratory and analgesic effects. Because its duration of
effect is shorter than that of some opioids, patients have
to be closely monitored and repeat doses need to be given
if mandated. Flumazenil is a benzodiazepine reversal agent.
If administered, patients must be monitored for 2 hours to
ensure that they do not become re-sedated.
Clinical use
Many different medications are available for sedation
and analgesia during interventional radiological
procedures and the drug or drug combination will vary
depending on operator preference and skills. The following
principles may help to ensure safe and effective use:
• Sedative drugs should be easily titrated to the desired
clinical effect and should have a predictable onset and
duration of effect with a rapid recovery.
• Intravenous administration is favoured because it
results in a more reliable rate of onset.
• Each drug should be given in increments.
• Appropriate time intervals need to be left between
increments to allow the drug effect to be evaluated
before the next incremental dose or a different drug
is administered.
• Drug combinations need to be used prudently and
according to the required effect and patient response.
• Repeated increments need to be given throughout
the procedure to maintain an adequate level of
patient comfort.
Safety aspects
Staff and skills
All personnel responsible for the administration
of sedation and analgesia and monitoring must be
capable of recognising and acting on complications
of over-sedation. Personnel should be capable of
maintaining airway patency and assisted ventilation
and it is recommended that advanced cardiac lifesupport
skills be immediately available. Two qualified
individuals must be present to ensure adequate care.
The radiologist is responsible for overseeing drug
administration and ensuring patient safety while a
second trained person (e.g. a nurse) must be present to
monitor the patient. The practice of a single operator
providing sedation should be condemned. Physicians and
medical personnel involved in sedation should undergo
regular re-certifications of advanced cardiac life support.
Staff should also receive training in the use of sedative
drugs and in the appropriate monitoring and management
of complications.6,9,15
Equipment and settings
Appropriate equipment and drugs required for
cardiopulmonary resuscitation and airway support
should be available in the area where sedation is conducted. In addition, adequate suctioning facilities,
airway control devices such as endotracheal tubes and
laryngoscopes, defibrillators and reversal agents should
be available.
Monitoring and patient care
 |
| Table 3. Recommendations for monitoring during analgo-sedation in
interventional radiological procedures |
Monitoring during sedation is the key to a safe practice.
All patients receiving moderate sedation should receive
supplemental oxygen through nasal prongs or by mask
and should have adequate venous access. Patients must
be continuously monitored to assess the depth of
sedation and to recognise signs of over-sedation.
Vital signs (blood pressure, pulse, respiratory rate)
should also be monitored continuously at appropriate
intervals. Electrocardiographic monitoring should be
used in patients with significant cardiovascular disease
undergoing sedation. All patients should be monitored
by pulse oximetry, although monitoring oxygenation is
not a substitute for monitoring ventilatory function.
Deeply sedated patients can hypoventilate and become
significantly hypercapnic without becoming hypoxic if
they are given supplemental oxygen. End-tidal CO2
monitoring may detect respiratory depression sooner
than pulse oximetry.16-18 Table 3 summarizes
recommendations for monitoring during analgosedation
in interventional radiological procedures.
Post-sedation care
Patients continue to be at significant risk of developing
complications related to sedation and analgesia
following the procedure. Continued observation and
monitoring should be carried out in an appropriate
area until the patients are at their baseline level of
consciousness. The following discharge criteria are
recommended:
• Patients should have returned to baseline level
of consciousness.
• Vital signs are stable within acceptable limits.
• Sufficient time should have elapsed following
administration of reversal agents to ensure that
patients do not become re-sedated.
• Outpatients should be discharged in the presence of
a responsible adult who will accompany them home.
Non-pharmacological analgesia and anxiolysis
Non-pharmacological methods of analgesia and
sedation such as hypnosis and anodyne therapy have been successfully used in interventional radiology and
have been shown to significantly reduce drug
requirements. Furthermore, adjunct hypnosis is a
cost-effective method during interventional procedures.
Although the training of staff is reported to be
relatively simple, the practice of using nonpharmacological
methods is not yet widespread.19-22
Conclusions
The safety and comfort of patients is the main priority
in patient management. The provision of sedation carries
the risk of potentially life-threatening complications
and adherence to recommended guidelines is therefore
mandatory. Choice of agents, techniques and personnel
for proper care should be based on the specific needs of
patients. To ensure the safety of all patients undergoing
sedation and analgesia, training of staff and provision of
support facilities for maximum patient care are
also important.
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