CONTROLLED HYPOTENSIVE CONTROLLED HYPOTENSIVE ANAESTHESIAANAESTHESIA

…what is safe ?…what is safe ?

Dr Hussain AlmejadiDr Hussain Almejadi

AL RAZI HospitalAL RAZI Hospital

• Definition.Definition.• History and evolution.History and evolution.• Physiology.Physiology.• Blood pressure goal.Blood pressure goal.• Contraindications.Contraindications.• Techniques.Techniques.• Anaesthetic management.Anaesthetic management.• Our experience in Al RAZI hospital. Our experience in Al RAZI hospital.

• why should we be bothered with why should we be bothered with hypotensive anaesthesia ?hypotensive anaesthesia ?– Decrease blood loss.Decrease blood loss.– Improve operative field.Improve operative field.– Decrease duration of surgery.Decrease duration of surgery.

Decrease in blood loss by 55 % Decrease in blood loss by 55 % and shorten the operating time and shorten the operating time by one hour .by one hour .

. . Sum DC, Chung PC, Chen WCSum DC, Chung PC, Chen WC::    Deliberate hypotensive Deliberate hypotensive anesthesia with labetalol in reconstructive surgery foranesthesia with labetalol in reconstructive surgery for scoliosisscoliosis. Acta Anaesthesiol Sin 1996 Dec;34(4):203-207. Acta Anaesthesiol Sin 1996 Dec;34(4):203-207

Significant less blood loss and Significant less blood loss and improving of the surgical field.improving of the surgical field.

Precious DS, Splinter W, Bosco DPrecious DS, Splinter W, Bosco D::    Induced hypotensive Induced hypotensive anesthesia for adolescent orthognathic surgeryanesthesia for adolescent orthognathic surgery J Oral Maxillofac Surg 1996 Jun;54(6):680-683J Oral Maxillofac Surg 1996 Jun;54(6):680-683

Intraoperative blood loss is 40% Intraoperative blood loss is 40% less.less.

Nelson CL, Fontenot HJNelson CL, Fontenot HJ: : Ten strategies to reduce blood loss in Ten strategies to reduce blood loss in orthopedic surgeryorthopedic surgery Am J Surg 1995,  N°6A (Suppl.), 170:64-68 Am J Surg 1995,  N°6A (Suppl.), 170:64-68

Deliberate hypotension in orthopedic Deliberate hypotension in orthopedic surgery reduces blood loss, surgery reduces blood loss, a meta a meta analysis of RCTanalysis of RCT. .

CANADAIN JOURNAL OF ANESTHESIA 2007CANADAIN JOURNAL OF ANESTHESIA 2007McMaster ,Hamilton,Ontario.McMaster ,Hamilton,Ontario.

17 ARTICLES. 17 ARTICLES.

CONCLUSION : Deliberate hypotension does CONCLUSION : Deliberate hypotension does reduce blood loss.reduce blood loss.

DefinitionDefinition

• It is a State of induced hypotension It is a State of induced hypotension during anaesthesia to reduce during anaesthesia to reduce bleeding and improve the surgical bleeding and improve the surgical field adjusted to the patient’s field adjusted to the patient’s age ,pre-operative blood pressure age ,pre-operative blood pressure and past medical history. and past medical history.

DefinitionDefinition

• Effect VS Safety .Effect VS Safety .• Reduction in systolic blood pressure to Reduction in systolic blood pressure to 80 -90 mmHg.80 -90 mmHg.• Decrease in MAP to 50-60 mmHg in Decrease in MAP to 50-60 mmHg in

normotensive patients.normotensive patients.• Reduction in MAP by 30% of the baseline Reduction in MAP by 30% of the baseline

values.values.

HistoryHistory

• 1917 Harvey Cushing for neurosurgery.1917 Harvey Cushing for neurosurgery.• 1943 Kolhstaedt and Page on dogs arterial bleeding.1943 Kolhstaedt and Page on dogs arterial bleeding.• 1946 Gardner arteriotomy.1946 Gardner arteriotomy.• 1948 High spinal.1948 High spinal.• 1951 High epidural.1951 High epidural.• 1951 Enderby ganlion blockade .1951 Enderby ganlion blockade .• 1960 Murtagh halothane.1960 Murtagh halothane.• 1962 Moraca sodium nitroprusside.1962 Moraca sodium nitroprusside.• 1967 Dimant pacemaker.1967 Dimant pacemaker.• 1978 Fahmy nitroglycerin.1978 Fahmy nitroglycerin.• 1981 Zimpfer verapamil.1981 Zimpfer verapamil.• 1982 Fukunaga adenosine .1982 Fukunaga adenosine .

PhysiologyPhysiology

• Cerebral circulation.Cerebral circulation.

• Coronary circulation.Coronary circulation.

• Renal circulation.Renal circulation.

Cerebral AutoregulationCerebral Autoregulation

Cerebral CirculationCerebral Circulation

• PaCO2 .PaCO2 .

• PaO2.PaO2.

• Temperature.Temperature.

• Volatile agents.Volatile agents.

• Vasodilators.Vasodilators.

Coronary CirculationCoronary Circulation

• Dependent on aortic diastolic blood Dependent on aortic diastolic blood pressure.pressure.

• Myocardium extracts most of the Myocardium extracts most of the oxygen delivered.oxygen delivered.

• Circulation is autoregulated .Circulation is autoregulated .

Renal CirculationRenal Circulation

• Autoregulation over the range 80-Autoregulation over the range 80-180 mmHg ( Miles and Venton 1954 )180 mmHg ( Miles and Venton 1954 )

• MAP less than 75 mmHg leads to MAP less than 75 mmHg leads to decrease in GFR ( Larson et al, decrease in GFR ( Larson et al, 1974 )1974 )

• Opioids and inhalational agents Opioids and inhalational agents stimulate ADH release (Stunn 1974 )stimulate ADH release (Stunn 1974 )

Respiratory SystemRespiratory System

• Increase in blood flow to the Increase in blood flow to the dependent areas.dependent areas.

• Vasodilators inhibits hypoxic Vasodilators inhibits hypoxic pulmonary vasoconstriction.pulmonary vasoconstriction.

• PaCO2 and EtCO2 gradient increase. PaCO2 and EtCO2 gradient increase.

Blood Pressure GoalBlood Pressure Goal

• Reduce blood loss.Reduce blood loss.

• Improve the surgical field .Improve the surgical field .

ContraindicationsContraindications

• Anaethetist factors.Anaethetist factors.

• Patients factors.Patients factors.

Anaesthetist factorsAnaesthetist factors

• Lack of understanding of the Lack of understanding of the technique.technique.

• Lack of technical experience.Lack of technical experience.

• Inability to monitor the patient Inability to monitor the patient adequately.adequately.

Patient factorsPatient factors

• Cardiac disease .Cardiac disease .• Diabetes .Diabetes .• Anemia.Anemia.• Hepatic disease.Hepatic disease.• Ischaemic cerebrovascular disease.Ischaemic cerebrovascular disease.• Renal disease.Renal disease.• Respiratory insufficiency.Respiratory insufficiency.• Severe systemic hypertension.Severe systemic hypertension.• Intolerance to drugs used for hypotensive Intolerance to drugs used for hypotensive

anaesthesia. anaesthesia.

Absolute contraindicationsAbsolute contraindications

• Known drug allergy.Known drug allergy.

• Inability to monitor the patient Inability to monitor the patient adequately.adequately.

• Unfamiliarity with the technique.Unfamiliarity with the technique.

Morbidity and MortalityMorbidity and Mortality

1954 little et al 1954 little et al – mortality 1 in 291 mortality 1 in 291 – morbidity 1 in 31.morbidity 1 in 31.– Systolic pressure below 80 mmHg.Systolic pressure below 80 mmHg.

2008 karol et al Anaesthes and 2008 karol et al Anaesthes and Anlgesia.Anlgesia.

– NO DIFFERENCE.NO DIFFERENCE.

TechniquesTechniques

MAP = CO MAP = CO xx SYSTEMIC VASCULAR SYSTEMIC VASCULAR RESISTANCE RESISTANCE

Decrease cardiac outputDecrease cardiac output

• Reduce blood volume.Reduce blood volume.

• Dilate capacitance vessels.Dilate capacitance vessels.

• Decrease cardiac contractility .Decrease cardiac contractility .

• Decrease of heart rate.Decrease of heart rate.

Peripheral vascular Peripheral vascular resistanceresistance

• Blockade of alpha adrenergic Blockade of alpha adrenergic receptors.receptors.

• Blockade of autonomic ganglion.Blockade of autonomic ganglion.

• Ralaxation of vascular smooth Ralaxation of vascular smooth muscle.muscle.

Mechanical manoeuversMechanical manoeuvers

• Positioning .Positioning .

• Positive airway pressure.Positive airway pressure.

• Spinal anesthesia.Spinal anesthesia.

• Epidural anesthesia.Epidural anesthesia.

Pharmacologic techniquePharmacologic technique

• Ideal agentIdeal agent - E- Ease of administrationase of administration - Predictable & dose-dependent effect - Predictable & dose-dependent effect - Rapid onset/offset- Rapid onset/offset - Quick elimination without the - Quick elimination without the production of toxic metabolitesproduction of toxic metabolites - Minimal effects on blood flow to vital- Minimal effects on blood flow to vital organsorgans

Inhalational anestheticsInhalational anesthetics

negative inotropic effectnegative inotropic effect vasodilation vasodilation

AdvantageAdvantage

• Provides surgical Provides surgical anesthesiaanesthesia

• Rapid onset/offsetRapid onset/offset• Easy to titrateEasy to titrate• Cerebral protectionCerebral protection

DisadvantageDisadvantage

• Decreases CODecreases CO• Cerebral Cerebral

vasodilationvasodilation

Sodium nitroprussideSodium nitroprusside D Direct vasodilator (nitric oxide release)irect vasodilator (nitric oxide release)

AdvantageAdvantage• Rapid onset/offsetRapid onset/offset• East to titrateEast to titrate• Increases COIncreases CO

DisadvantageDisadvantage• Cyanide/thiocyanate Cyanide/thiocyanate

toxicitytoxicity

• Increased ICPIncreased ICP

• Increased pulm. shuntIncreased pulm. shunt

• Sympathetic Sympathetic stimulationstimulation

• Rebound hypertensionRebound hypertension

• Coronary stealCoronary steal

• TachycardiaTachycardia

NitroglycerinNitroglycerin D Direct vasodilator (nitric oxide release)irect vasodilator (nitric oxide release)

AdvantageAdvantage• Rapid onset/offsetRapid onset/offset• East to titrateEast to titrate• Limited increase Limited increase

in heart ratein heart rate• No coronary stealNo coronary steal

DisadvantageDisadvantage• Lack of efficacy-Lack of efficacy-

depending on depending on anesthetic techniqueanesthetic technique

• Increased ICPIncreased ICP• Increased pulm. Increased pulm.

shuntshunt• MethemoglobinemiaMethemoglobinemia• Inhibition of plt. Inhibition of plt.

aggregationaggregation

Beta adrenergic antagonistBeta adrenergic antagonist Beta adrenergic blockade (decreased Beta adrenergic blockade (decreased myocardial contractility)myocardial contractility)

AdvantageAdvantage

• Rapid onset/offsetRapid onset/offset• Decreased Decreased

myocardial O2 myocardial O2 consumptionconsumption

• No increase in ICPNo increase in ICP• No increase in pulm. No increase in pulm.

shuntshunt

DisadvantageDisadvantage

• Decreased CO Decreased CO • Heart blockHeart block• BronchospasmBronchospasm• Limited efficacy Limited efficacy

when used alonewhen used alone

Calcium channel blockerCalcium channel blocker - vasodilation- vasodilation

AdvantageAdvantage

• Rapid onsetRapid onset

• Limited increase in HRLimited increase in HR

• Increase COIncrease CO

• No effect on airway No effect on airway reactivityreactivity

• Increased GFR/urine Increased GFR/urine outputoutput

DisadvantageDisadvantage

• Prolonged duration of Prolonged duration of actionaction

• Increased ICPIncreased ICP

• Increased pulm. shuntIncreased pulm. shunt

RemifentanilRemifentanil

• Remifentanil is an OPIOIDRemifentanil is an OPIOID• Pure Pure agonist agonist

– little binding at little binding at and and receptors receptors Rapid onset/offsetRapid onset/offset Decreases blood pressure & heart Decreases blood pressure & heart

raterate No need for additional use of a potentNo need for additional use of a potent hypotensive or adjunct agents hypotensive or adjunct agents

Remifentanil Key ConceptsRemifentanil Key Concepts

• Remifentanil is an Remifentanil is an ESTERESTER. Metabolized by nonspecific esterases in . Metabolized by nonspecific esterases in

blood and tissueblood and tissue

• Anesthesia maintained with highAnesthesia maintained with high--dose remifentanil will be associated dose remifentanil will be associated with rapid recoverywith rapid recovery..Within 5-10 minutes of turning off an infusion Within 5-10 minutes of turning off an infusion

there is virtually no residual remifentanil drug there is virtually no residual remifentanil drug effecteffect

Dosing and AdministrationDosing and Administration

• Dex. should be administered using a Dex. should be administered using a controlled infusion device.controlled infusion device.

• Dex. dosing should be individualized and Dex. dosing should be individualized and titrated to the desired clinical effecttitrated to the desired clinical effect

• For adult patients Dex. is generally For adult patients Dex. is generally initiated with a infusion of 1mcg/kg over initiated with a infusion of 1mcg/kg over 10 minutes, followed by a maintenance 10 minutes, followed by a maintenance infusion of 0.2 to 0.7 mcg/kg/hrinfusion of 0.2 to 0.7 mcg/kg/hr

• It is not necessary to discontinue Dex. It is not necessary to discontinue Dex. prior to extubationprior to extubation

• Comparison between dexmedetomidine and Comparison between dexmedetomidine and remifentanil for controlled hypotension during remifentanil for controlled hypotension during tympanoplastytympanoplasty..

• CONCLUSIONSCONCLUSIONS: : Infusion of dexmedetomidine, at Infusion of dexmedetomidine, at the doses used in this study, was less effective than the doses used in this study, was less effective than remifentanil in achieving controlled hypotension, remifentanil in achieving controlled hypotension, good surgical field exposure condition and good surgical field exposure condition and surgeons' satisfaction during tympanoplastysurgeons' satisfaction during tympanoplasty..

2008-05, Eur J Anaesthesiol2008-05, Eur J Anaesthesiol.., 25, 25((55):):369-74369-74. . Epub 2008 Epub 2008

Feb 25Feb 25..

Preoperative managementPreoperative management

• Thorough knowledge by the Thorough knowledge by the anaesthetist.anaesthetist.

• Proper patient evaluation and Proper patient evaluation and selection.selection.

• HB of 10 g/dl.HB of 10 g/dl.

• Arterial blood gas analysis sampling.Arterial blood gas analysis sampling.

• Good level of anxiolytics ,analgesics .Good level of anxiolytics ,analgesics .

• Vagolytic drugs should be avoided.Vagolytic drugs should be avoided.

Intraoperative managementIntraoperative management

• Stress free induction.Stress free induction.

• Nasal intubation ?.Nasal intubation ?.

• Enough peripheral venous access.Enough peripheral venous access.

• Pressure points.Pressure points.

MonitoringMonitoring

• Invasive blood pressure .Invasive blood pressure .

• Invasive blood pressure.Invasive blood pressure.

• ECG V5 lead with ST segment analysis.ECG V5 lead with ST segment analysis.

• Central venous pressure.Central venous pressure.

• Urine output.Urine output.

• Temperature.Temperature.

• Blood loss.Blood loss.

Fluid therapyFluid therapy

• Deficit replacement.Deficit replacement.

• Maintenance.Maintenance.

• Blood loss.Blood loss.

• Induced hypotension should start at Induced hypotension should start at the time of mucosal incision .the time of mucosal incision .

• Only to the level needed to reduce Only to the level needed to reduce bleeding.bleeding.

• Only during specific surgical phase.Only during specific surgical phase.

Postoperative managementPostoperative management

• Rebound hypertension.Rebound hypertension.

• Reactionary hemorrhage.Reactionary hemorrhage.

Our experience in AL RAZI Our experience in AL RAZI hospitalhospital

• Strong points.Strong points.

• Area of improvement.Area of improvement.

Strong pointsStrong points

• One OT is allocated for hypotensive One OT is allocated for hypotensive anaesthesia/TIVA.anaesthesia/TIVA.

• Propofol – remifentenyl.Propofol – remifentenyl.

• Invasive monitoring is a must.Invasive monitoring is a must.

Area of improvementArea of improvement

• Patients selection.Patients selection.

• Reduction in blood transfusion.Reduction in blood transfusion.

Future studiesFuture studies

• Prospective.Prospective.

• Control of age and physical status.Control of age and physical status.

• Bigger sample size.Bigger sample size.

• Type of surgery.Type of surgery.

• Controlled studies.Controlled studies.

• Same technique.Same technique.

• Doppler technique.Doppler technique.

THANK YOUTHANK YOU

THANK YOUTHANK YOU