Transcript Controlled Hypotension

HYPOTENSIVE ANESTHESIA
By
Khosrou Naghibi MD
Isfahan University of Medical
Sciences
Synonyms of DH
• Controlled hypotension
• Induced hypotension
• Circulatory control
• Hypotensive anesthesia
Purpose of DH:
• This technique was deployed to:
• Decrease Blood loss
• Improve operative field
• Decrease duration of Sx.
DELIBERATE
HYPOTENSION
To reduce bleeding •
To reduce blood transfusions •
Indicated:
Oromaxillofacial surgery
Endoscopic sinus microsurgery
Middle ear microsurgery
Spinal surgery
Neuro surgery
Major orthopaedic surgery
Prostatectomy
CV surgery
Liver transplant surgery
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DH Cont..
Definition
 Reduction in systolic blood pressure
to 80-90 mmHg
 Decrease in MAP to 50-65 mmHg
in normotensive patients
 Reduction in MAP by one-third of its
baseline values
DELIBERATE
HYPOTENSION
DEFINITION:
Reduction of the systolic blood pressure •
to 80-90mmHg
Reduction of mean arterial pressure •
(MAP) to 50-65 mmHg
30% reduction of baseline MAP •
DRUG. 2007; 67 (7): 1053-76
DH Cont..
Safe level of DH
• Depends on the pt.
• Healthy young pt. tolerate mean B.P. as
low as 50-60 mmHg.
• Ch. hypertensive pts. tolerate a mean of
B.P. no more than 25% lower than the
base line.
• Pts. with TIA may not tolerate any
decrease in cerebral perfusion pressure.
• Extremes :
• Hypotension always avoided
• Hypotension produced for any desire of
surgeon.
DH Cont..
Indication
Neurosurgery
Orthopedics: THR, spine fusion
Ear, Nose, Throat/Oral
Surgery
Gynecologic/urologic:
radical pelvic surgery, prostatectomy
Religious blood refusal, rare blood type,
difficult cross matching
DH Cont..
Contraindications
• Infants
• Systemic disease compromising major
organ function
• Renal, cerebral, coronary artery diseases
• Pt. with sickle cell anemia
• Polycythemia (uncorrected)
DH Cont..
Significant reduction in O2
delivery:
• ANEMIA
• SEVER LUNG DISEASE
• LOW CARDIAC OUTPUT
DH Cont..
Absolute contraindications
• Cerebrovascular disease
• Inexperience of the anesthesiologist
DH Cont..
Complications
• Underperfusion of major organ:
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Cerebral thrombosis
Hemiplegia
ATN
Massive hepatic necrosis
Blindness
Retinal artery thrombosis
Ischemic optic neuropathy
• Surgical complications
• Reactionary hemorrhage
• Hematoma formation
COMPLICATIONS OF
DELIBERATE
HYPOTENSION
COMPLICATION
INCIDENCE(%)
Cerebral thrombosis
0,1 – 0,2
Coronary artery
thrombosis
0,3 – 0,7
Renal failure
COMMENT
0 – 0,2
Hepatic failure
Postop pulmonary
dysfunction
Rebound hypertension
Increased bleeding at
operative site
Inadequate hemostasis
(due to hypotension)
RELATIVE CONTRA INDICATIONS TO
INDUCED HYPOTENSION
Ischemic cerebrovascular desease •
Coronary artery desease •
Hypovolemia •
Anemia •
Severe hypertension •
Extremes of age •
Hemodynamic effects of
Hypotensive drugs:
TACHYPHYLAXIS:
• Response despite repeated
administration of the drug
• More frequently seen in young adults
• Has been reported with most drugs.
TACHYCARDIA.
Control of heart rate:
The key to preventing tachyphylaxia is
control of heart rate:
• Inhalational anesthesia
• Avoiding fluid overload
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Pre-Op. sedation + IV opioid.
Position:
Artérial and venous pressure
Reduction of bleeding : position
10-15° head up tilt position
head restHead position :
rotation
- controlateral ear
- jugular vein
- bracchial plexus
- carotid artery
DELIBERATE HYPOTENSION: NEW
TECHNIQUES
Use the natural hypotensive effects of •
anaesthetic drugs with regard to the
definition of the ideal hypotensive agent:
Easy to administer
Short onset time
Disappears quickly when stopped
Rapid elimination
No toxic metabolites
Negligible effect on vital organs
Predictable effect
Dose dependent effect
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Remifentanil Key Concepts
Remifentanil is an OPIOID 
Pure m agonist 
little binding at k, s, and d receptors
The effects of remifentanil are identical 
with other commonly used opioids
fentanyl
alfentanil
sufentanil
DELIBERATE HYPOTENSION: NEW
TECHNIQUES
Epidural anaesthesia •
- Propofol Remifentanil: •
- Isoflurane Remifentanil: •
- Desflurane
- Sevoflurane
Epinephrine and inhalation anesthetics
5.4 mcg/kg with isoflurane
10 mcg/kg with sevoflurane
10 mcg/kg with desflurane
BJA 2008 Jan; 100(1): 50-4
Rhinology 2007 mar; 45 (1): 72-8
Eur J. Anaesthesiol 2007 may; 24 (5): 441-6
AM J. Rhinol 2005 sept-oct; 19 (5): 514-20
Laryngoscopie 2003 aug; 113 (8): 1369-73
Monitoring
during
Controlled hypotension
DH Cont..
1. Arterial blood pressure
2. ECG – myocardial perfusion
Risk of:
Tachycardia
Bradycardia
Arrhythmias
St-sigment changes
Ishcemia
3. Gas exchange:
Capnography
is essential:
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As a disconnection alarm
Indicator of air embolism
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Correlation between ETCO2 & PaCO2 is limited
VD/VT) during DH
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Helps avoid hyperventilation in DH
Pulse oximetry
4. Temperature
Method
• Physiologic technique
• Pharmacologic technique
DELIBERATE
HYPOTENSION AGENTS
USED ALONE: •
Inhalation anaesthetics
Sodium nitroprusside
Nitroglycerin
Trimethaphan
Prostaglandine E1
Adenosine
Remifentanil
Agents for spinal
anaesthesia
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ALONE OR COMBINED: •
Calcium channel •
antagonists
Beta-Blockers •
Fenoldopam •
COMBINED: •
ACE inhibitors •
Clonidine •
Physiologic technique
 Body positioning
 Hemodynamic effects of
mechanical ventilation
 Changes in
heart rate & circulatory
volume
Pharmacologic technique
• Ideal agent
- Ease of administration
- Predictable & dose-dependent effect
- Rapid onset/offset
- Quick elimination without the
production of toxic metabolites
- Minimal effects on blood flow to vital
organs
1)Inhalational anesthetics
– negative inotropic effect
vasodilation
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Advantage
Provides surgical
anesthesia
Rapid
onset/offset
Easy to titrate
Cerebral
protection
Disadvantage
• Decreases CO
• Cerebral vasodilation
3)Sodium nitroprusside
Direct vasodilator (nitric oxide release)
Disadvantage
• Cyanide/thiocyanate
toxicity
• Increased ICP
• Increased pulm. shunt
• Sympathetic
stimulation
• Rebound hypertension
• Coronary steal
• Tachycardia
Advantage
• Rapid onset/offset
• East to titrate
• Increases CO
4)Nitroglycerin
Direct vasodilator
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(nitric oxide release)
Advantage
Rapid
onset/offset
East to titrate
Limited increase
in heart rate
No coronary steal
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Disadvantage
Lack of efficacydepending on
anesthetic technique
Increased ICP
Increased pulm. shunt
Methemoglobinemia
Inhibition of plt.
aggregation
5)Beta adrenergic antagonist
Beta adrenergic blockade
(decreased myocardial
contractility)
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Advantage
Rapid onset/offset
Decreased
myocardial O2
consumption
No increase in ICP
No increase in pulm.
shunt
Disadvantage
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Decreased CO
Heart block
Bronchospasm
Limited efficacy
when used alone
6)Calcium channel blocker
- vasodilation
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Advantage
Rapid onset
Limited increase in
HR
Increase CO
No effect on
airway reactivity
Increased
GFR/urine output
Disadvantage
• Prolonged duration
of action
• Increased ICP
• Increased pulm.
shunt
Intravenous drugs
7)Remifentanil
• Remifentanil is an OPIOID
• Pure m agonist
• little binding at k, s, and d receptors
 Rapid onset/offset
 Decreases blood pressure & heart rate
 No need for additional use of a potent
hypotensive or adjunct agents
Remifentanil Key Concepts
• Remifentanil is an ESTER
. Metabolized by nonspecific esterases in blood
and tissue
• Anesthesia maintained with high-dose
remifentanil will be associated with
rapid recovery.
 Within 5-10 minutes of turning off an infusion
there is virtually no residual remifentanil drug
effect
Remifentanil
Potential Benefits
• Changes in remifentanil drug effect
rapidly follow changes in the
remifentanil infusion rate.
• The analgesic effects are evanescent.
• Post-operative analgesic needs must be
anticipated.
Remifentanil Metabolism
• Extremely rapid
• Not influenced by:
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Hepatic disease
Renal disease
Pseudocholinesterase deficiency
Administration of neostigmine
Very young age
• Modest decrease in elderly patients
Anesthesia Technique
• Monitoring
• Induction
• Position head up 450
• BP drop range 20% - 40% of baseline
• HR range 50 – 60 beat/min
Observation, cont’d
• PONV:
• Nausea & Vomiting.
• prophylactic anti-emetics are given perioperatively.
DH…
• Ear Sx.
• Produce bloodless surgical field for
microscopy
• Stapedectomy :
• <0.75ml of blood loss
condition
• >1.5ml of blood loss
good op.
bad op. condition
• In middle ear Sx. Even slight hemorrhage
fibrosis so
B.P.
Improves the
results.
Deliberate Hypotension In
FESS
 Moderate DH (systolic pressure 80
80mmHg)
• Reduces the capillary bleeding
 Bloodless operative field provides
good sinuses surgical conditions
CONCLUSION
• Proper initiation of DH depends on the
anesthesiologist.
• Desired level of blood pressure can be
achieved by skillful use of gravity,
ventilation & drugs helped by proper
monitoring and adequate Post Op. care.
• Teamwork with cooperation between
anesthesiologist and surgeon is of great
importance in the care of pts. who
undergo deliberate hypotension.
THANK YOU
THANK YOU