Chapter 13Controlled

Hypotension

Introduction

1.history ： 1917 ， the concept was first proposed by Cushing ； 1946 ， was introduced into clinical practice by Gardner

1948 ， Griffiths - “hypotensive spinal technique” ； 1950 ， ganglionic blockade - pentamethonium ； 1962 ， sodium nitroprousside ； Subsequent techniques:β- adrenergic receptor blocking drugs, a combination of α- and β- adrenergic receptor blocking drugs, volatile anesthetics, purine derivatives

Introduction

2. Controlled/Induced/Deliberated Hypotension

3.Purpose ：（ 1 ） decrease blood loss

（ 2 ） improved visibility of the operative field

（ 3 ） decreasing the need for blood transfusions

（ 4 ） decreasing the transmitting disease by blood transfusion

Rationale of controlled hypotension

1. Major factors of maintain blood pressure

（ 1 ） cardiac output （ CO ）（ 2 ） total systemic vascular resistance （ TSVR ）（ 3 ） blood volume

（ 4 ） blood viscosity （ BV ） 组织血液灌流量 = （ π×MAP× 血管内径 4 ） （ 8× 血液粘度 × 血管长度）

Rationale of controlled hypotension

2. Controlled hypotension ：（ 1 ） TSVR ：　① Tension of vascular system　② MAP ≥ 32mmHg - sufficient hemoperfusion　③ Safe limit ： MAP ≥ 60 mmHg 　 Older ≥ 80 mmHg（ 2 ） CO ：　① Venous system ： capacitance vessel 　 70% total blood volume　② Venous dilatation → returned blood volume↓ 　 → CO↓→MAP

Effect of hypotension on organs function

一、 Central Nervous System ：1. Changes in cerebral hemodynamics （ CBF ）（ 1 ） Autoregulation of CBF ： 60~150 mmHg

（ 2 ） MAP < 60mmHg → Autoregulation deprivation

（ 3 ）↑ FiO2→Tolerance for hypoxia↑

（ 4 ） PaCO2

2.Changes of using sodium nitroprusside and trimethaphan

3.Changes of using isoflurane

Effect of hypotension on organ function

二、 Heart ： 1.Maintenance of an oxygen supply sufficient ：

2. Autoregulation of coronary circulation ：

3.Suppress tachycardia ： β1-receptor - esmolol

labetalol 、 urapidil

4.Reduce metabolic requirements ： nitroglycerin

Effect of hypotension on organ function

三、 Kidneys ： 1. Autoregulation of Kidneys ： 80~180 mmHg

2. SBP↓75 mmHg → GFR↓→ anuresis

3.Sufficient Oxygen supply kidney vasodilatation

4. Normal renal function → albuminuria 、 cast 、 red cell

5. Nephropathy → sever disadvantage 、 renal inadequacy

Autoregulation of renal blood flow

5

4

3

2

1

0

100 200

平均动脉压（ mmHg)

肾血流(m

l/min/g

肾重)

Effect of hypotension on organ function

四、四、 Splanchnic CirculationSplanchnic Circulation ：： 1. liver hypoxic hazard1. liver hypoxic hazard

2. gastrointestinal tract2. gastrointestinal tract

五、五、 EyeEye ：：六、六、 Skin and MuscleSkin and Muscle ：：

Indications and Indications and ContraindicationsContraindications

一、一、 IndicationsIndications ：：1. Operations of tissue and organ which blood 1. Operations of tissue and organ which blood supply supply abundantly ：： head and neckhead and neck2. 2. Cardiovascular operationsoperations ：： aortic aneurysmaortic aneurysm 、、 patent ductus arteriosuspatent ductus arteriosus 、、 intracranial vascular malformationintracranial vascular malformation

3. Loss of large volume blood3. Loss of large volume blood ：： surgery on large tumorssurgery on large tumors 、、 total hip arthroplastytotal hip arthroplasty

Indications and Indications and ContraindicationsContraindications

4. 4. Clear operating field ：： middle earmiddle ear 、、 microsurgerymicrosurgery

5. 5. Hypertension 、、 intracranial hypertension 　 intraocular hypertension 　 during anesthesia which causing severe harmful consequence

6. Contraindications for blood transfusion6. Contraindications for blood transfusion

7. Religious beliefs7. Religious beliefs ： ： preclude blood transfusionpreclude blood transfusion

Indications and Indications and ContraindicationsContraindications

二、二、 ContraindicationsContraindications ：： 1. Absolute contraindications1. Absolute contraindications ：：（（ 11 ）） Organic diseaseOrganic disease ：： cerebrovascular diseasecerebrovascular disease

renal dysfunctionrenal dysfunction liver dysfunctionliver dysfunction severe coronary artery diseasesevere coronary artery disease long - term hypertensionlong - term hypertension arteriosclerosisarteriosclerosis

Indications and Indications and ContraindicationsContraindications

（（ 22 ）） Hypovolemia Hypovolemia 、、 severe anemiasevere anemia 、、 and respiratory insufficiencyand respiratory insufficiency

（（ 33 ）） Aspect of techniqueAspect of technique ：： not not familiar

with the theory and technique of technique of

controlled hypotension

Indications and Indications and ContraindicationsContraindications

2. Relative contraindications2. Relative contraindications ：：（（ 11 ）） Elderly patient or babyElderly patient or baby ；；（（ 22 ）） Chronic oxygen deficiencyChronic oxygen deficiency ；；（（ 33 ）） Ischemic peripheral angiopathyIschemic peripheral angiopathy ：： severe peripheral claudicationsevere peripheral claudication ；；（（ 44 ）） PhlebitisPhlebitis 、、 thrombusthrombus ；；（（ 55 ）） GlaucomaGlaucoma

COMPLICATIONSCOMPLICATIONS 1. Complications1. Complications ：：（（ 11 ）） Cerebral infarctionCerebral infarction 、、 cerebral anoxiacerebral anoxia

（（ 22 ）） Coronary artery embolizationCoronary artery embolization 、、 cardiac failurecardiac failure

（（ 33 ）） Renal dysfunction, anuria and oliguriaRenal dysfunction, anuria and oliguria

（（ 44 ）） Respiratory insufficiencyRespiratory insufficiency

（（ 55 ）） EmbolismEmbolism

（（ 66 ）） Postoperative bleedingPostoperative bleeding

（（ 77 ）） Persistence hypotensionPersistence hypotension

（（ 88 ）） Analepsia delayAnalepsia delay

COMPLICATIONSCOMPLICATIONS2.Reason2.Reason ： ： Hypotension → Hypotension → perfusion pressure↓↓

→ → slow slow blood flow → → thrombogenesis

3.Correlation factors3.Correlation factors ：：（（ 11 ）） Do not Do not control the the indications strictly

（（ 22 ）） Hypotension and and persistence time too long too long

（（ 33 ）） Fault of of technical management

（（ 44 ）） Insufficient transfusion →→hypovolemia

（（ 55 ）） Respiration management improperly

（（ 66 ）） Postoperative care is not strict

COMPLICATIONSCOMPLICATIONS

4. Prevention and Management4. Prevention and Management ：：（（ 11 ）） Control the the indications strictly

（（ 22 ）） Keep vein open 、 、 fluid infusion in time precise estimated blood loss 、 （（ 33 ）） Appropriate hypotension adaptive process

（（ 44 ）） Enhance respiration management maintain PaCOPaCO2 2 normal keep the keep the airway unobstructed

（（ 55 ）） EEnhance postoperative care

TECHNIQUES TO INDUCE TECHNIQUES TO INDUCE CONTROLLED HYPOTENSIONCONTROLLED HYPOTENSION

一、一、 Pharmacologic TechniquesPharmacologic Techniques ：： 1. M1. Medication combination ：： fast and short - acting vasoactive drug

volatile anesthetic + /orβ- /orβ- receptorblocker

2. 2. Forte ：： enhance hypotension effect→↓→↓drug

consumption→→prevent adverse effect

（（ reflex tachycardia 、、 rebound

hypertension 、、 drug fast ））

TECHNIQUES TO INDUCE TECHNIQUES TO INDUCE CONTROLLED HYPOTENSIONCONTROLLED HYPOTENSION

二、二、 Commonly Used DrugsCommonly Used Drugs ：： 1. Sodium Nitroprusside1. Sodium Nitroprusside ：： first selectfirst select

0.01%0.01%

0.5~8.0 μg/kg/min ivgtt0.5~8.0 μg/kg/min ivgtt

total amount ≤ 1.5mg/kg≤ 1.5mg/kg

2. Nitroglycerin2. Nitroglycerin ：： 3. Volatile Anesthetic Drugs3. Volatile Anesthetic Drugs

TECHNIQUES TO INDUCE TECHNIQUES TO INDUCE CONTROLLED HYPOTENSIONCONTROLLED HYPOTENSION

4. α- Adrenergic receptor-blocking drug4. α- Adrenergic receptor-blocking drug ： ： phentolaminephentolamine 、、 urapidilurapidil

5.5. Purine DerivativesPurine Derivatives ：： ATPATP

6.6. EsmololEsmolol ：： short-acting cardioselective β-short-acting cardioselective β- adrenergic receptor-blocking drugadrenergic receptor-blocking drug

7.7. LabetalolLabetalol ：： block both αblock both α11 - and β - and β11- receptors- receptors

also blocks βalso blocks β22 -receptors -receptors

8.8. NicardipineNicardipine ：： calcium channel blocking drugcalcium channel blocking drug 600~800 μg/kg/h600~800 μg/kg/h

TECHNIQUES TO INDUCE TECHNIQUES TO INDUCE CONTROLLED HYPOTENSIONCONTROLLED HYPOTENSION

三、三、 Commonly Used TechniquesCommonly Used Techniques ：：

11 ．． Volatile Anesthetic DrugsVolatile Anesthetic Drugs ：：

（（ 11 ）） HalothaneHalothane ：： deep anesthesia→→

inhibit myocardium→CO↓→CO↓

（（ 22 ）） EnfluraneEnflurane ：： dilate peripheral vessels

（（ 33 ）） IsofluraneIsoflurane ：： dilate peripheral vessels

TECHNIQUES TO INDUCE TECHNIQUES TO INDUCE CONTROLLED HYPOTENSIONCONTROLLED HYPOTENSION

2. Angiotenic2. Angiotenic ：：（（ 11 ）） Sodium NitroprussideSodium Nitroprusside ：： ① ①Note ：： Solution instability→→protect from light Suddenly withdrawal→→rebound hypertension →→captopril long-term use→→quickly drug tolerance compensatory tachycardia→→propranolol

② ②Cyanide poisoningCyanide poisoning ：： large dose or long time →→cyanate cumulation

TECHNIQUES TO INDUCE TECHNIQUES TO INDUCE CONTROLLED HYPOTENSIONCONTROLLED HYPOTENSION

（（ 22 ）） NitroglycerinNitroglycerin

（（ 33 ）） Calcium channel blockerCalcium channel blocker

（（ 44 ）） α- α- Adrenergic receptor-blockerAdrenergic receptor-blocker ① ① PhentolaminePhentolamine

② ② UrapidilUrapidil

（（ 55 ）） ATPATP

Monitoring During Monitoring During Induced HypotensionInduced Hypotension

一、一、 Requirement of Anesthetic TechniqueRequirement of Anesthetic Technique

二、二、 Precise estimate of Blood LossPrecise estimate of Blood Loss

三、三、 Extent of Deliberate HypotensionExtent of Deliberate Hypotension

Safe limitSafe limit ：： MAP ≥ 60~70 mmHgMAP ≥ 60~70 mmHg ； ； hypertension 、、 vascular sclerosis 、、 olderolder ：≥ ：≥ 40% 40% original BPP

preoperative DBP - SBP = 0~10 mmHgDBP - SBP = 0~10 mmHg

Monitoring During Monitoring During Induced HypotensionInduced Hypotension

四、四、 Body positioning Body positioning

五、五、 Ventilation and Oxygenation Ventilation and Oxygenation

六、六、 MonitoringMonitoring ：： BPBP 、、 ECGECG 、、 SPOSPO22 、、 PPETETCOCO22 、、 urine volumeurine volume 、、 blood gas analysisblood gas analysis 、 、

HbHb 、、 HctHct

七、七、 Termination of hypotension Termination of hypotension

八、八、 Management of postoperationManagement of postoperation