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Anesthesia inInterventional Radiology
K.Vishma, PoornachandraThejeswi, andG.S.Triveni
5
Key Messages
1. Interventional radiology has become increasingly complex, necessitating effective anaesthesia care to ensure
patient safety and comfort. The presence of anaesthesiologist is required for complex and prolonged procedures
and patients with comordidities.
2. In this chapter we have discussed the challenges faced by
anaesthesiologists, minimal necessary equipments
required for the conduct of moderate or deep sedation and
general anaesthesia. Anesthetic techniques and drugs
used depend on the procedure- specic and patient specic factors.
3. Anesthethesiologlists should be aware of specic challenges that may arise during and after IR procedures and
should be prepared to mitigate these situations.
Interventional radiologist should have knowledge of
commonly used anaesthetic drugs and procedures. There
should be a collaboration between radiologists, anaesthesiologists and other healthcare professionals to ensure
optimal patient outcome.
4. Considerations in specic IR procedures and a brief note
on management of aspiration, blood loss, difcult airway
and resuscitation are included in this chapter.
5.1 Introduction
Radiological intervention procedures are being carried out in
increasing numbers and with increasing complexity.
Interventional radiology procedures are minimally invasive
procedures but remain a potential source of anxiety and pain
K. Vishma (*)
Father Muller Medical College, Mangalore, India
P. Thejeswi
Department of Surgery, Kasturba Medical College,
Mangalore, India
G. S. Triveni
Department of Obstetrics and Gynecology, Vardhman Mahavir
Medical College and Safdarjung Hospital, Delhi, India
for patients. Since pain is often felt when any hardware is
inserted percutaneously, it is routinely performed under local
anesthesia. Managing the acute pain and anxiety associated
with medical procedures is a healthcare challenge [1]. There
is an increasing need for anesthetic care in IR suites for
patients requiring prolonged and complex procedures and
for patients with comorbidities. This chapter will review the
common concerns regarding the anesthetic management of
patients undergoing IR procedures.
5.2 Pre-procedure Tasks
5.2.1 Overview ofChallenges
1. Location of the IR suite: In many institutions, the IR suite
is located distant from the main operating area and is not
designed for the delivery of anesthetic care.
2. Radiation exposure: The anesthesiologist may be exposed
to the ionizing radiation, adjustment of drug dosage, or
troubleshooting monitoring equipment. Radiation dose is
determined by the duration of exposure time, distance
from the radiation source, and whether shields are used or
not. The major source of radiation is the X-ray tube, but
there may be leakage through the collimators and radiation scattered from surfaces surrounding the patient’s
head [2]. The amount of exposure responds to the inverse
square law: radiation intensity decreases proportionally
with the inverse of the square of the distance from the
source of radiation.
Therefore, precise radiation protection depends on the
following:
• Anesthesiologist should stay as far as possible, when-
ever feasible. A connected multiparameter monitor
from remote locations is used.
• They should wear protection apparels, particularly
lead aprons, thyroid shields, protective eyewear, and
radiation exposure badges.
• Movable lead glass screens should be used [2].
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024
S. H. Chandrashekhara (ed.), Textbook of Interventional Radiology, https://doi.org/10.1007/978-981-97-9601-4_5
35
36
K. Vishma et al.
3. Unfamiliar personnel: The persons working in the IR suite
may not be familiar with anesthesia care, particularly anesthesia-related emergencies. Hence, the resuscitation drugs
and equipment should be placed near the IR suite. Prior
communication with specialized personnel outside the IR
suite to ensure rapid response at the time of emergency.
5.2.2 Equipment andLogistic Organization
The American Society of Anaesthesiology (ASA) has specied the statement on the minimal necessary equipment and
organization for NORA [2].
In each location there should be:
• A reliable source of oxygen sufcient for as long as the
entire procedure (ideally piped and full backup E
cylinder)
• Adequate and reliable suction
• A reliable removal system for anesthetic gases (scaveng-
ing system)
• A bag valve mask, adequate anesthesia drugs, supplies,
and equipment
• Adequate monitoring systems and anesthesia machine
• An emergency cart with the debrillator and emergency
drugs
• Sufcient space for equipment and personnel to allow
rapid access to the patient
• Adequate illumination of the patient, anesthesia machine,
and monitoring equipment [2]
for the possibility of pregnancy. After a case is approved,
scheduled written and informed consent is taken. Good consent
must include the type of anesthesia delivered, risks, and benets involved. Many of the IR procedures may require antibiotic
prophylaxis. The rationale behind prophylaxis is to prevent
contamination of passage of needles and catheters through contaminated parts of the body and into the bloodstream [2].
5.3 Anesthesia Techniques
The choice of anesthesia technique depends on patientspecic or procedure-specic considerations. It can be monitored anesthesia care (MAC) with minimal or deep sedation,
regional anesthesia, or general anesthesia.
The following considerations must be monitored:
A. Patient-specic factors
• Level of consciousness
• Hemodynamic instability
• Inability to lie supine
• Inability to cooperate due to pain or claustrophobia
• Difcult airway
• Obesity/obstructive sleep apnea
• Patient preference
B. Procedure-specic factors
• Type of procedure
• Duration and complexity of the procedure
• Need for an uncomfortable position
• Need for intermittent apnea
• Exposure to radiation
5.2.3 Management ofPatients During
Transport totheIR Suite
Patients with cerebrovascular diseases or injuries may have
highly unstable conditions and rapidly deteriorating neurological status [2]. During transport, the patient should be
accompanied by skilled personnel to monitor the patient’s
medical condition. The transport team should carry anesthesia emergency drugs and resuscitation equipment.
5.2.4 Pre-anesthetic Evaluation
Typically, the interventional radiologist consults anesthesia
personnel prior to the IR procedure to determine the type of
anesthesia care needed. The anesthesiologist must evaluate the
patient’s comorbidities, history of allergy to the contrast dye,
understand the nature of the procedure, and the interventionalist’s specic requirements including the position of the patient,
how painful the procedure will be, and the duration of the procedure. Also, women of childbearing age should be assessed
In many instances, interventional procedures is achieved
with conscious sedation or monitored anesthesia care
(MAC). In conscious sedation, the patient responds knowingly to verbal or tactile stimulation. No interventions are
required to maintain airway patency.
Midazolam 0.02–0.1mg/kg iv initially, if a further dose is
required 25% of the initial dose can be repeated after 3–5min
(Table5.1).
MAC includes monitoring the patient throughout the
procedure and administrating supplemental oxygen by
nasal cannula. Anesthesia drugs can be given intravenously
to provide anxiolysis (midazolam), analgesia (fentanyl),
and sedation (propofol). Propofol is ideal for MAC because
of the rapidity of onset and ease of titratable. It has a short
context sensitivity half-time and short effect-site equilibration time. It has a good quality of recovery and a low
incidence of nausea and vomiting. Though Propofol has a
rapid onset of action and quick recovery from sedation,
there are concerns about safety and potential side effects
when used by non- anesthesiologists. It has the potential to
induce general anesthesia, and there is no antagonist to
5 Anesthesia inInterventional Radiology
Table 5.1 Anesthetic drugs
Drug Dose Onset of action Duration of effect Route of administration
Midazolam 0.02–0.1mg/kg iv initially, if a further
dose is required 25% of the initial dose
can be repeated after 3–5min
Fentanyl 1mcg/kg 1min 0.5–1h Intravenous injection
Propofol Induction dose 1–2.5mg/kg
maintenance
Infusion 50–200mcg/kg/min
Dexmedetomidine 1mcg/kg over 10min
Maintenance 0.2–1mcg/kg/h
Table 5.2 Local anesthetic drugs
Drug Onset of action Duration of effect Maximum dose Route of administration
Lignocaine 2% 10–15min 1–2h Without adrenaline: 5mg/kg
Bupivacaine 0.25% 15–30min 2–3h 3mg/kg Subcutaneous injection
1–5min 1–4h Intravenous injection
30–60s The induction dose lasts for
10min.
The recovery was seen
within 5min after stopping
the infusion
With adrenaline: 7mg/kg
Intravenous injection
Intravenous injection
Subcutaneous injection
37
reverse its action. Propofol may be administered by an
anesthesiologist for moderate sedation, or under the direction of the proceduralist at a dose of 1–2.5mg/kg. When
used by non- anesthesiologists for the purpose of sedation,
there are guidelines by ASA stating that personnel must be
prepared to respond to deep sedation and loss of patent
airway if these complications inadvertently occur during
sedation.
Dexmedetomidine is a selective alpha 2 receptor agonist
that produces sedation and analgesia. It has minimal effects
on respiratory function and better patient satisfaction.
Regardless of the planned anesthesia technique, the anesthesiologist must always be ready to induce general anesthesia if necessary.
ASA dened four levels of sedation/analgesia as follows
[3–8]:
A. Minimal sedation (anxiolysis): It is a drug-induced
state during which patients respond normally to verbal
commands. Cognitive function and coordination are
impaired, and cardiovascular and respiratory functions
are not affected.
B. Moderate sedation/analgesia (“conscious” sedation):
In conscious sedation, the patient responds knowingly to
verbal or tactile stimulation. No interventions are
required to maintain a patent airway. Cardiovascular
function is maintained.
C. Deep sedation/analgesia: It is a drug-induced depres-
sion of consciousness during which patients cannot be
easily aroused but respond purposefully following
repeated or painful stimulation. The ability to maintain
ventilatory function may be impaired. Cardiovascular
function is usually maintained.
D. General anesthesia: It is a drug-induced depression of
consciousness where the patients are not arousable, even
by painful stimulation. Patients often require assistance
in maintaining a patent airway, and positive-pressure
ventilation may be required because of drug-induced
depression of neuromuscular function and depressed
spontaneous ventilation. Cardiovascular function may be
impaired.
For amnesia, sedative-hypnotic drugs should be given
at titratable doses. Giving large boluses can compromise
the cardio-respiratory functions. Opioids are useful in
patients with cardiac diseases. They also reduce the pain
due to positioning, procedure-related pain, and pain due
to pneumatic tourniquet. Administering high-dose opioid
can cause awareness and recall of intra procedure events
because opioids lack amnestic property. In patients who
are on chronic opioid requirement (e.g., oncological/
oncosurgical patients) opioids can cause transient effects
on signal processing due to neuroplastic changes in frontal and parietal cortices.
5.3.1 Local Anesthesia
The majority of IR procedures can be done under local anesthesia. Commonly used local anesthetics are lignocaine 1%
and bupivacaine 0.25% (Table5.2).
Epidural anesthesia and newer fascial plane blocks (e.g.,
serratus anterior plane, erector spinae plane, quadratus lumborum blocks) are the newer modalities of administering
anesthesia along with anxiolysis of the patient to remain
calm during the procedure.
38
K. Vishma et al.
Table 5.3 ASA fasting guidelines
Ingested material Minimum fast (h)
Clear uids 2
Breast milk 4
Infant formula milk 4–6
Non-human milk 6
Light meal 6
Heavy meal (contains fat and meat) 8
5.4 Pediatric IR Procedures
They require more extensive involvement of the anesthesia
team and increased attention to minimize radiation exposure.
Each child should be individually assessed and kept nil by
mouth (nbm) before sedation. ASA fasting guidelines are
shown in Table5.3 [3, 4].
For the ease of intravenous cannulation, EMLA (eutectic
mixture of a local anesthetic) cream can be applied on a suitable vein prior to cannulation. Oral sedation with syrup
Triclofos can be given to children less than 4years of age
(dose 50–100mg/kg). Oral sedation does not work well with
older children and those children, who are unable to cooperate will require a general anesthetic.
5.5 Anesthesia Considerations
The patient physical status and the anesthetic drug inuence on cardiovascular and respiratory systems need to be
assessed. The adequate immobility of the patients during
the procedure is essential for the success of the procedure
(e.g., aortic stenting, CNS interventions, GI bleeding, etc.).
The quick recovery following the IR procedure has to be
ensured. Anticoagulation monitoring may pose a challenge
in certain procedures such as thrombolysis. The inadvertent
complications, which may occur during the procedures like
embolism, occlusion, bleeding, etc., need to be instantly
managed. Adequate intra and post-procedure pain management (e.g., embolization procedures, post-embolization
syndrome) is essential. Anesthetic personnel are also
responsible for the transport to IR suites, especially critically ill patients [9].
The anesthetic agent chosen must have adequate efcacy,
predictable onset, and duration of action. Recovery should
be rapid for the patient after the procedure. Compared to oral
administration, intravenous administration offers a more predictable onset time and absorption rate. It is important to
titrate drugs in small increments. Before repeating the drug,
adequate time should be allowed. It is always essential to be
vigilant when a drug combination is used. If the IR procedure gets prolonged, it may be necessary to repeat the dose.
If the patient receives more than minimal sedation or analgesia, oxygen may be given via through facemask [9].
5.6 Type ofAnesthesia
Anesthetic techniques vary according to procedure-specic
and patient-specic factors. Most of the IR procedures in
cooperative patients are performed by interventional radiologists under local anesthesia. In uncooperative patients,
sometimes conscious sedation is necessary. The IR procedures in the pediatric population and high-risk cardio-pulmonary disease patients may require general anesthesia.
Some complex procedures, such as TIPS and CNS procedures, may be performed under GA. The management of
pain and inducing sedation can be a challenge in liver failure
patients [9], as most of the drugs depend on the liver for its
metabolism. Opioid drugs and benzodiazepine dosage needs
to be reduced. In renal failure patients, short-acting opioids
like fentanyl are preferred. Prolonged sedative effect is seen
with midazolam; hence, dose reduction is necessary.
5.7 Dicult Airway Management
In some patients with difcult airway anatomy and obese
patients, securing the airway may pose a challenge in an IR
suite, which may have limited resources. Anesthesiologist
should evaluate the patient for potential airway difculties
assess the patients airway. All the necessary hardware in the
IR suite should be checked before inducing the patient for
anesthesia. Need for advanced airway techniques such as
beroptic intubation and videolarygoscope should be
considered.
5.8 Immediate Treatment ofAspiration
Appropriate fasting guidelines should be advised to patients
who require sedation/GA. The use of sedatives and anaesthetics increase the risk of aspiration by diminishing gag
reex.
Nil by mouth orders (6h for solid food, 4h for liquids,
and 2h for clear uids like water) should be instructed to
patients to avoid any risk of aspiration.
In spite of this if aspiration occurs, immediately turn the
patient to one side and oropharyngeal suction should be done
using a wide suction catheter. Provide supportive care by
administeing oxygen and antibiotic therapy.
5.9 Management ofBlood Loss
andDeranged Coagulation
Parameters
Adequate blood has to be arranged in cases of high-risk
patients of bleeding. The deranged coagulation parameters
have to be corrected before the procedures. In case of emer-
5 Anesthesia inInterventional Radiology
39
gent procedures, prior arrangements of fresh frozen plasma,
platelets, etc. should be made. Continous monitoring of
heart rate, blood pressue should be done. In cases of active
bleeding immediate uid resuscitation and blood transfusion is necessary and preparedness for shifting to operating
room for surgical intervention if embolization technique
fails.
5.10 Considerations forSpecic IR
Procedures
Anesthetic considerations and potential complications differ
for specic procedures performed in the IR suite.
Neurologic Procedures In emergencies, focused assessment of the patient’s mental status and neurological decits
must be documented. Also, baseline blood pressure and any
coexisting cardiovascular comorbidities should be noted.
Though interventional neuro-radiological procedures are
rarely painful, they will require a non-moving, cooperative
patient and episodes of controlled ventilation. This is ideally
achieved by total i.v. anesthesia (TIVA) or sometimes inhalation anesthetics along with intermittent boluses of neuromuscular blocking agent or infusion and/or remifentanil
infusion.
Spine Interventions Spine biopsies are usually performed
under LA. Sometimes, sedation or MAC with additional
intravenous analgesic injection may be needed before painful cement injections in vertebroplasty and kyphoplasty
procedures.
Gynecological Procedures The majority of the procedures
are performed under LA. Adequate pain management is
essential for uterine artery embolization. Conscious sedation
or MAC may be needed in some uncooperative patients.
Hepatic Interventions The pharmacodynamics and pharmacokinetics of most anesthetic drugs are altered in hepatic
disorders. The majority of the hepatic IR procedures are performed under LA. Conscious sedation or MAC may be
needed in some uncooperative patients. GA is preferred in
patients with hepatic encephalopathy or ascites to prevent
the risk of aspiration or when a prolonged procedure is anticipated. The liver ablative procedures, preoperative tumor
embolization, portal vein embolization, percutaneous tumor
embolization, and TACE (transarterial chemoembolization)
can be done under conscious sedation, MAC, or GA depending on the individual patient’s status.
Renal IR Procedures Most of the procedures are performed under LA. Adequate pain management is essential
for ablation or embolization procedures for the renal mass.
Conscious sedation or MAC may be needed in selected
individuals.
Gastrointestinal IR Procedures The majority of the procedures are performed under LA. Conscious sedation or
MAC may be needed in selected patients. Moderate to deep
sedation is often sufcient if there is no risk of aspiration, but
the need to induce general anesthesia may arise.
Vascular IR Procedures Most of the vascular procedures
are performed under LA.Conscious sedation or MAC may
be needed in some uncooperative patients. Peripheral angioplasty which needs an immobile limb can be done with
regional blocks like popliteal nerve block or popliteal-sciatic
nerve block. Balloon angioplasty for upper limb can be done
under brachial block. Endovascular laser ablation (EVLA) or
endovascular laser therapy (EVLT) can be done tumescent
local anesthesia or femoral sciatic block or under subarachnoid block with minimal sedation.
Cardiopulmonary Resuscitation in IR Suite As mentioned earlier in the chapter, the persons working in the IR
suite may not be familiar with anesthesia care, particularly
anesthesia-related emergencies. Hence, the resuscitation
drugs and equipment should be placed near the IR suite.
Prior communication must be made with specialized personnel outside the IR suite to ensure rapid response at the time
of emergency. Cardiac arrest in IR suite is rare, but if it
occurs it is dangerous. Patient susceptibility to cardiac arrest
depends upon the age, ASA physical status, procedure type,
and urgency. Recent study shows that incidence of cardiac
arrest is more in pediatric age group and in cases taken up as
emergency. Vascular procedures posed more risk than nonvascular procedures. Cardiac arrest is a damaging adverse
event associated with multiorgan dysfunction, traumatic
complications, and death. Careful patient selection, preprocedure optimization, and vigilant monitoring during the
procedure can prevent cardiac arrest in IR suite. Position of
the patient, emergency access to the airway, giving chest
compressions is a task in this setup. Detection of arrest may
be delayed especially when all the monitors are not available, which may lead to delay in initiating cardiac
compressions.
5.11 Conclusion
FNAC and Biopsy Procedures
The majority of the proce-
dures are performed under LA.Pediatric patients may require
GA.
Adequate anesthesia and analgesia in IR procedures will
ensure patients have less pain, lower intraprocedural risk,
and shorter recovery time. The presence of an anesthesiolo-
40
K. Vishma et al.
gist in IR suites will make these complex procedures safer
for the patients and easier for the radiologists. The complex, time-consuming procedures and patient comorbidities
necessitate good anesthesia care in interventional
radiology.
References
1. Chiumello D. Practical trends in anesthesia and intensive care
2020–2021. Springer International Publishing AG. ISBN:
3031146115.
2. Martin ML, Lennox PH. Sedation and analgesia in the interven-
tional radiology department. J Vasc Interv Radiol. 2003;14(9 Pt
1):1119–28.
3. American Society of Anesthesiologists Task Force on Sedation
and Analgesia by Non Anesthesiologists. Practice guidelines for
sedation and analgesia by non anesthesiologists. Anesthesiology.
2002;96(4):1004–17.
4. Mesbah A, Thomas M.Preoperative fasting in children. BJA Educ.
2017;10:346–50.
5. Practice guidelines for sedation and analgesia by nonanesthesiologists. Anesthesiology. 2002;96:1004–17.
6. Innes G, Murphy M, Nijssen-Jordan C, Ducharme J, Drummond
A.Procedural sedation and analgesia in the emergency department.
Canadian Consensus Guidelines. J Emerg Med. 1999;17:145–56.
7. Krauss B, Green SM.Sedation and analgesia for procedures in children. N Engl J Med. 2000;342:938–45.
8. Arepally A, Oechsle D, Kirkwood S, Savader SJ.Safety of conscious sedation in interventional radiology. Cardiovasc Intervent
Radiol. 2001;24:185–90.
9. Garg R, Pandey R, Darlong V, Punj J.Anesthetic considerations for
interventional radiology. Internet J Anesthesiol. 19(1):4.
Periprocedural Bleeding
andThrombotic Considerations
inInterventional Radiology
NehaBaijal, HarpinderSingh, andS.H.Chandrashekhara
6
Key Messages
1. An understanding of the pathways of hemostasis is
essential to understand the periprocedural risk of bleeding and thrombosis.
2. Primary hemostasis involves the vessel wall and platelets, while secondary hemostasis involves various coagulation factors. Abnormality in any of these can lead to
an increased periprocedural risk.
3. Pre-procedure workup includes a thorough history to
identify a bleeding or thrombotic tendency, relevant
comorbidities, and drug intake which may impact the
hemostatic pathways.
4. Periprocedural risk of bleeding depends on patient- and
procedure-related factors.
5. Patient factors affecting bleeding risk include hypertension, renal disease, liver disease, bleeding history, recent
stroke, age, and drug intake.
6. Laboratory investigations to assess bleeding risk test the
primary and secondary hemostatic mechanisms, including platelet count, PT-INR, aPTT, and
thromboelastography.
7. Procedures can be divided into low-risk and high-risk based
on ease of detection and management of a bleed if it occurs.
8. High-risk procedures require laboratory investigations
and optimization of parameters prior to the procedure,
while low-risk procedures in low-risk patients require no
additional workup.
9. Patients who require anticoagulants or antiplatelets, such
as for coronary artery disease, mechanical heart valves,
and stroke, need careful balancing of the bleeding risk
due to the procedure and thrombotic risk from the underlying disease if antithrombotic agents are discontinued.
N. Baijal (*) · H. Singh
Department of Radiodiagnosis and Interventional Radiology, All
India Institute of Medical Sciences, Delhi, India
S. H. Chandrashekhara
Department of Radiodiagnosis and Interventional Radiology,
IRCH, All India Institute of Medical Sciences, Delhi, India
10. Bridging of anticoagulants may have to be done in such
patients to discontinue long-acting irreversible anticoagulants and cover the periprocedural period with shortacting drugs like heparin that can be titrated and reversed
if required.
6.1 Introduction
Hemostasis is a complex physiological process that involves
interaction between platelets, von Willebrand factor, endothelium, and coagulation factors. Understanding the mechanism of hemostasis and pathophysiology of various
conditions affecting the hemostatic process allows the interventional radiologist to minimize periprocedural complications related to bleeding and thrombosis.
In this chapter, we begin with a brief review of the physiology of hemostasis and relevant laboratory investigations.
This will be followed by a discussion of the various factors
that predispose a patient to bleeding or thrombotic complications and evidence-based guidelines on their management in
the periprocedural period.
6.2 Physiology ofHemostasis
The rst step in hemostasis after injury to the vessel wall is
reactive vasoconstriction. Endothelial injury leads to the
exposure of the extracellular matrix containing collagen and
von Willebrand factor (vWF). This results in platelet adhesion, activation, and aggregation at the site of injury with the
formation of a temporary platelet plug [1]. This is known as
primary hemostasis. The tissue factor released after endothelial injury activates factor VII and thus triggers the extrinsic
pathway of coagulation. Thrombin is produced as a result,
and it activates the intrinsic pathway, acting as a catalyst for
several steps of the coagulation cascade. The nal common
pathway leads to the formation of brin monomers, which
undergo cross-linking to form a brin polymer mesh. Fibrin,
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2024
S. H. Chandrashekhara (ed.), Textbook of Interventional Radiology, https://doi.org/10.1007/978-981-97-9601-4_6
41
42
EXTRINSIC PATHWAY
INTRINSIC PATHWAY
Fig. 6.1 Flowchart showing
the coagulation pathway of
secondary hemostasis
Tissue Factor
Prothrombin
Time (PT)
VII VIIa
SECONDARY HAEMOSTASIS
Ca
Ca
X
Prothrombin
Xa
Ca
Va
Thrombin
VIIIa
IXa
XIa
XIIa
Ca
IX
N. Baijal et al.
XII
XI
Activated Partial
Thromboplastin
Time (aPTT)
along with the trapped platelets, forms a stable clot.
Simultaneous activation of plasminogen and anticoagulants
such as antithrombin III and protein C and S limits the extent
of thrombus formation and restores blood ow in the injured
vessel. An understanding of the pathways of hemostasis is
essential to understand the periprocedural risk of bleeding
and thrombosis. The coagulation pathway of secondary
hemostasis is shown in Fig.6.1.
6.3 Pre-procedural Workup
A detailed history must be taken to assess the bleeding or
thrombotic risk in the patient [2]. Past history of excessive
bleeding, family history of a bleeding diathesis, and history
of intake of antiplatelet or anticoagulant drugs must be elicited. The patient’s comorbidities should be reviewed to identify any factor that may lead to periprocedural hemorrhagic
or thrombotic complications.
Several laboratory investigations that are available to
assess the coagulation prole have been criticized for not
being sensitive or specic enough to accurately predict the
bleeding risk. A patient with a normal coagulation prole
may develop excessive bleeding, while some patients with
deranged parameters might not develop any clinically signicant complications [2].
Clinical risk stratication scores have thus been developed to predict the risk of bleeding based on several clinical
trials on patients with non-valvular atrial brillation.
Although not validated specically for interventional radiology procedures, the HAS-BLED score is a commonly used
scoring system based on various clinical parameters, including hypertension, abnormal renal or liver function, stroke,
bleeding history or predisposition, labile INR, elderly, drugs/
FibrinogenFibrin
alcohol concomitantly [3]. Score≥3 has moderate discriminatory performance in predicting periprocedural bleeding
[4].
Commonly performed laboratory investigations for
assessing the coagulation cascade include platelet count,
prothrombin time (PT), and activated partial thromboplastin
time (aPTT).
6.3.1 Prothrombin Time (PT-INR)
Prothrombin time (PT) is the time taken for the formation of
a brin clot after the addition of tissue factor, calcium, and
phospholipid to plasma invitro, and it represents the integrity of the extrinsic and the common pathways [5]. It is standardized for different laboratories using the International
Normalized Ratio (INR). PT is commonly used to monitor
patients on oral anticoagulation with vitamin K antagonists.
Isolated prolongation of PT occurs in factor VII deciency,
while other coagulopathies usually cause derangement of
aPTT as well.
6.3.2 Activated Partial Thromboplastin Time
This test assesses the intrinsic and common pathway of the
coagulation cascade and represents the time taken for brin
clot formation after the addition of contact activator, phospholipid, and calcium to plasma invitro [5]. It is commonly
used to monitor patients receiving unfractionated heparin
(UFH). Isolated prolongation of aPTT is seen in hemophilia,
prekallikrein deciency, and in the presence of lupus
anticoagulant.
(monomers)
(aPTT)
PT and aPTT
Ca
Fibrin Polymers
6 Periprocedural Bleeding andThrombotic Considerations inInterventional Radiology
43
Other coagulopathies such as liver disease, disseminated
intravascular coagulation, dilutional coagulopathy, vitamin
K deciency, and use of anticoagulant medications such as
direct thrombin inhibitors result in prolongation of both
PT-INR and aPTT. Patients receiving anticoagulants may
have an increased risk of bleeding despite the lab values
being normal. Conversely, lupus anticoagulant would cause
a prolonged aPTT but lead to a prothrombotic state. Thus,
the British Committee for Standards in Hematology and the
National Institute for Health and Clinical Excellence (NICE)
advise against indiscriminate use of coagulation screening
before invasive procedures or surgery [2, 6].
6.3.3 Viscoelastic Tests
Viscoelastic tests include thromboelastography (TEG),
thromboelastometry (ROTEM), and sonoclot. Activators
such as kaolin, heparinase, aprotinin, or tissue factor are
added to whole blood and placed in a cup that moves relative
to the rest of the machine. An electromechanical transducer
detects the resistance to motion as the brin clot is formed
and a graph is obtained. The graph can be divided into four
sections that provide information on the time to rst brin
formation, the kinetics of brin polymerization, measures of
clot strength, and clot lysis. As they assess both clot formation and lysis, viscoelastic assays are said to be better at predicting bleeding risk in liver disease as compared to other
standard tests, which can only detect hypocoagulable states.
They can be used to guide brinogen replacement in liver
disease patients with bleeding complications [7].
6.4 Bleeding Risk inInterventional
Radiology Procedures
An understanding of factors that may lead to bleeding complications in the periprocedural period is essential in order to
prevent and manage them appropriately. These factors may
be procedure-related or patient-related.
6.4.1 Procedure-Related Bleeding Risk
Some procedures are associated with an inherent risk of
bleeding owing to the nature of the intervention being performed. Preprocedural work-up must be tailored accordingly
to identify and correct any conditions that may lead to hemorrhagic complications. Society of Interventional Radiology
(SIR) consensus guidelines divide procedures into two
groups based on associated bleeding risk. Procedures are
said to pose a low risk if the incidence of bleeding is low
(<1.5%) and if bleeding is easy to detect and manage.
Drainage or biopsy of supercial lesions that are easily com-
pressed and do not have major blood vessels in their vicinity
are classied as procedures with low bleeding risk. Routine
laboratory screening of all patients posted for procedures
known to have a low bleeding risk is not recommended.
Patients at a higher risk of bleeding due to factors such as
liver disease, renal disease, malignancy, mechanical heart
valves, or medication intake should undergo pre-procedure
testing. The recommended range of platelets is >20,000/μL
and INR is <2.0–3.0. While arterial interventions using a 6F
or smaller arterial sheath, diagnostic angiography, and embolotherapy are also considered to pose a low risk for periprocedural bleed, INR <1.8 is recommended for femoral access
and INR<2.2 for radial access [8].
On the other hand, all biliary, portal venous, and urinary
tract interventions pose a high bleeding risk because bleeding at such sites can be difcult to control and may lead to
major complications. Similarly, drainage or biopsy of lesions
located in deep organs within the chest, abdomen, or pelvis
are associated with a high procedural bleeding risk. In
patients undergoing high risk procedures, routine screening
is recommended. Platelets should be transfused if the platelet
count is <50,000/μL and INR should be <1.5–1.8. Liver disease results in unique changes in the physiology of coagulation, and management recommendations are discussed
separately in subsequent sections.
A list of bleeding risks associated with various procedures and recommended preprocedural screening is given in
Table6.1.
These recommendations are based on consensus guidelines developed on the basis of limited evidence from studies
in various surgical and interventional procedures—not specically designed for image-guided interventions. Thus, the
strength of the recommendation is low. Also, the complex
hemostatic mechanisms and their derangements in a given
patient represent a challenging problem to be solved by a
team consisting of hematology, cardiology, and internal
medicine experts [8].
6.4.2 Periprocedural Management
ofAntiplatelet andAnticoagulant
Agents
The decision to withhold anticoagulant and antiplatelet
agents prior to a procedure depends upon the patient factors
including bleeding and thrombotic risks, bleeding risk associated with the procedure, and the duration of action of the
agent being given. The drug should be stopped well in
advance to minimize the incidence of excessive bleeding
during the procedure while ensuring that the patient is off
medication only for the minimum required period to reduce
the risk of thrombosis. The timing of withholding various
drugs with increased bleeding risk before a procedure is
given in Table6.2. These agents need to be withheld only
44
Table 6.1 Categorization of image-guided procedures according to their risk of bleeding [8]
Low-risk procedures High-risk procedures
• Screening for coagulation parameters not routinely recommended
• Recommended threshold for performing the procedure—platelet count
>20,000/mm
3
, PT/INR <2–3
• Procedures:
– Diagnostic arteriography
– Diagnostic venography
– Arterial interventions—sheath <6F, embolization
– Venous interventions—pelvis and extremities
– Transjugular liver biopsy
– IVC lter placement and removal
– Non-tunneled or tunneled venous catheter placement or removal
– Dialysis access interventions
– Supercial biopsy or abscess drainage
– Tunneled drainage catheter placement
– Exchange of gastrostomy, biliary, nephrostomy or abscess drainage
catheters
– Paracentesis, thoracocentesis
– Lumbar puncture
– Facet joint injections of thoracic and lumbar spine
• Recommended screening tests—platelet count, hemoglobin
level, PT/INR
• Recommended threshold for performing the procedure—
platelet count >50,000/mm
• Procedures:
– Arterial interventions—>7F, aortic, pelvic, mesenteric, and
neuro-interventions
– Venous interventions- intrathoracic and neuro-interventions
– Catheter-directed thrombolysis
– Transjugular intrahepatic portosystemic shunt
– Portal vein interventions
– Complex IVC lter removal
– Biliary interventions including cholecystostomy
– Urinary tract interventions
– Gastrostomy and gastrojejunostomy
– Intrathoracic or intraabdominal abscess drainage or biopsy
– Spine procedures- kyphoplasty, vertebroplasty, epidural
injections
– Facet joint injections of cervical spine
– Peripheral nerve blocks
– Peripheral joint or musculoskeletal injections
– Sacroiliac joint injections
– Trigger point injections
PT/INR prothrombin time/International normalized ratio
3
, PT/INR <1.5
N. Baijal et al.
Table 6.2 SIR guidelines for withholding antiplatelet and anticoagulant agents prior to the procedure and re-initiation after the procedure [8]
S no. Drug Withholding before the procedure Restarting after the procedure
Anticoagulant agents
1. Parenteral anticoagulants
1.A. Indirect thrombin inhibitors:
Unfractionated heparin 4–6h, check aPTT or factor Xa levels 6–8h
Low molecular weight
heparin
Fondaparinux 2–3 d if CrCl >50ml/min; 3–5 d if CrCl
24h, check anti-Xa levels if renal function
impaired
12h
24h
<50ml/min
1.B. Direct thrombin inhibitors:
Bivalirudin, argatroban 2–4h, check aPTT 4–6h
2. Oral anticoagulants
2.A. Vitamin K antagonist
Warfarin 5 d, till INR <1.8 1day
2.B. Direct factor Xa inhibitors:
Rivaroxaban Skip two doses if CrCl >30ml/min; three
24h
doses if CrCl <30ml/min
Apixaban Skip four doses if CrCl >50ml/min; six doses
24h
if CrCl 30–50ml/min
Betrixaban Skip three doses 24h
Edoxaban Skip two doses 24h
2.C. Direct thrombin inhibitors:
Dabigatran Skip four doses if CrCl <50mL/min; six to
24h
eight doses if CrCl <30–50mL/min
Antiplatelet agents
(continued)