IVRA Anesthesia: Technique, Safety & Contraindications

Regional Anesthesia (Spinal, Epidural, Nerve Block)

• Regional anesthesia involves using local anesthetics to block pain sensations in a large area of the body like an arm, leg, or abdomen
• This allows procedures to be performed on a specific region without the patient losing consciousness
• Combining regional anesthesia and analgesia with general anesthesia can provide optimal operating conditions and prolonged pain relief
• Pain relief from this enables faster post-op mobilization and earlier feeding, which speeds up rehab and recovery

Relative Indications

• Regional anesthesia helps avoid the risks of general anesthesia like difficult intubation or respiratory failure
• It can be requested by patients
• It delivers high-quality post-operative pain relief
• It quickens return to function

Relative Contraindications

• Uncooperative and restless patients are not suitable
• it is also not suitable for some psychiatric patients

Preparation for Injection

• Before injecting any local anesthetic, make sure the following are available:
• Intravenous cannula
• Tilting table or trolley
• Intermittent Positive Pressure Ventilation (IPPV) with oxygen

Essential Monitoring

• Patient monitoring should include:
• ECG
• Noninvasive blood pressure
• Pulse oximetry
• End-tidal carbon dioxide monitoring
• Additional needed support includes:
• Suction equipment, catheters
• Tranquilizers like midazolam
• Induction agents like Propofol
• Muscle relaxants like Suxamethonium
• Atropine
• Pressor agents like ephedrine
• Crystalloid and colloid solutions for infusion
• Resuscitation equipment and drugs including a defibrillator

Types of Regional Anesthesia

• Major types of regional anesthesia are peripheral nerve blocks and intravenous regional anesthesia

Peripheral Nerve Blocks

• A local anesthetic gets injected near a specific nerve or bundle to block pain from that area

Intravenous Regional Anesthesia (Bier's Block)

• Bier's block is a peripheral nerve block for body extremities, best for operations on the distal arm or leg, below the elbow or knee
• It's suitable for short surgical procedures, done in 40 mins or less
• Length of operating time is limited by tourniquet pain, which usually develops after 40–60 minutes
• In IVRA, the target region is exsanguinated to force blood out, then a tourniquet inflated to 100 mmHg above systolic blood pressure
• Anesthetic is then introduced intravenously into the limb and allowed to diffuse

Bier's Block Precautions

• Two intravenous cannulas should be placed, one distal to the tourniquet, one to the non-targeted arm
• Dose needed is 3-4 mg/kg of 0.5% plain solution of lidocaine or prilocaine
• Bupivacaine should never be used due to its cardiotoxicity leading to ventricular arrhythmias and death

Bier's Block Contraindications

• Crush injury to the limb, IVRA may cause further tissue damage secondary to hypoxia
• Reynold's disease (intermittent arteriolar vasospasm of distal limbs)
• Sickle cell anemia
• Scleroderma

Ultrasound-Guided Regional Anesthesia (USGRA)

• Ultrasound (US) to guide peripheral nerve blockade (PNB) was first used in Vienna in the mid-1990s
• Radiologists used ultrasound to guide needles for biopsy, which innovated PNB techniques
• Ultrasound-guided regional anesthesia techniques extends to brachial plexus and femoral blocks

Transversus Abdominis Plane (TAP) Block

• TAP block provides analgesia to the anterior and lateral abdominal wall
• It blocks the mid/lower thoracic and upper lumbar spinal nerves in the plane between transversus abdominis and internal oblique muscles
• Initial studies suggested T7-L1 blocks with bilateral injections, but later studies indicate T9/10 blocks
• TAP blocks are reliable for analgesia after surgery on the lower abdomen
• Hernia repair
• Open appendicectomy
• Caesarian section
• Total abdominal hysterectomy
• Radical prostatectomy

Spinal Cord Injections

• Local anesthetic is injected near the spinal cord and major nerves to block pain from a region like lower abdomen, hips, or legs
• Caudal block involves injecting local anesthetic into the epidural space through the sacral hiatus to anesthetize sacral and coccygeal nerve roots, indicated for skin grafting, perineal or lower limb surgery
• Spinal anesthesia (intradural) is done with an understanding of the anatomy: the spinal cord typically ends at L1 in adults and L3 in children
• Dural puncture above these levels can damage the spinal cord

Important Anatomy Landmarks

• A line joining the tops of the iliac crests is at L4 to L4/5
• Spinous process of T7 is at the inferior angle of the scapula
• Tuffier's line is located at the body of L4 or L4–L5 interspace

Advantageous Conditions / Procedures

• Spinal anesthesia is advantageous in surgeries of the lower limbs, perineum, pelvis, or abdomen.
• It is ideal in renal failure greater by two or three segments
• It is appropriate for cardiac disease, liver disease, obstetric anesthesia, full stomach, and anatomic distortions of the upper airway
• Spinal is also suited for TURP surgery

Levels of Block

• Sympathetic paralysis, sensory block, then motor nerve blockade occur sequentially

Technique and injection site

• The local anesthetic is injected directly into cerebrospinal fluid using a smaller needle
• Needle insertion site is between the third and fourth lumbar vertebrae
• The area is numbed with a local anesthetic, then the needle is carefully inserted into the spinal canal, and the anesthetic is injected without the use of a catheter
• This numbs the body sometimes above the site of injection
• The person may not be able to move his or her legs until the anesthetic wears off.

Distribution of anesthesia factors

• Injection site
• Shape of spinal column
• Patient height
• Angulation of needle
• Volume of CSF
• Characteristics of local anesthetic like density, and specific gravity
• Dose, Volume and Patient position during & after

Cardiovascular Effects of Spinal Anesthesia

• Blockade of Sympathetic Preganglionic Neurons
• Sends signals to arteries and veins
• Predominant action is venodilation
• Reduces venous return, stroke volume, cardiac output and blood pressure
• T1-T4 Blockade causes unopposed vagal stimulation
• This causes Bradycardia
• Associated with decrease venous return & cardioaccelerator fibers blockade
• Decreased venous return to right atrium causes decreased
• stretch receptor response

Hypotension Treatment

• Best treated using physiologic not pharmacologic methods
• Primary treatment is to increase the cardiac preload by administrating large IV fluid bolus of minimum 1 liter of crystalloids within 30 minutes prior to spinal placement
• A secondary pharmacological treatment is ephedrine, being more effective than Phenylephrine

Respiratory System Effects

• Appropriate spinal blockade has little effect on ventilation
• A high spinal may decrease functional residual capacity by paralysis of abdominal muscles
• Intercostal muscle paralysis interferes with coughing and clearing secretions
• Apnea can result due to hypo-perfusion of respiratory center

Immediate Complications

• Immediate risks include hypotension, bradycardia, cardiac arrest, or high/total spinal block leading to respiratory arrest, and urinary retention

Late Complications

• Late risks involve post-dural puncture headache (PDPH), backache, nausea, neurological deficit, bacterial meningitis and sixth cranial nerve palsy

Spinal Headache

• Spinal headaches are more common in women ages 13-40
• It is found that with Larger needle size may increase severity
• Onset usually occurs first- or second-day post-op
• Treatment involves:
• Bed rest
• Fluids
• Simple analgesia (paracetamol, aspirin and codeine)
• Caffeine and Blood patch

Blood Patch

• This can increase pressure of CSF by placing blood in epidural space
• May do no more than two
• 95% success with first patch
• Second patch may be done 24 hours after first

Epidural (Extradural) Anesthesia

• Occurs in the epidural space, which a potential space between the dura mater and ligament flavum, made up of vasculature, nerves, fat and lymphatic
• Extends from foramen magnum to the sacrococcygeal ligament being segmented and not uniform in distribution
• Anteriorly it is bounded by the posterior longitudinal ligament
• Laterally it is bounded by pedicles and intervertebral ligaments
• Posteriorly it is bounded by the ligament Flavum

Epidural Space Size

• Widest at Level L2 (5-6mm)
• Narrowest at Level C5 (1-1.5mm)
• Average adult: 4-6cm (80%) from skin to epidural space
• Obese adult: up to 8cm
• Thin adult: 3cm
• Total Volume: 118ml

Technique and injection

• Involves the insertion of a hollow needle and a small, flexible catheter in the space
• Location is between the spinal column and outer membrane of the spinal cord (epidural space) in the middle or lower back
• Area needs be numbed with a local anesthetic
• The needle is then inserted and removed after the catheter has passed through it

Test Dose for correct placement

• 1.5% Lido with Epi 1:200,000
• Tachycardia (increase >30bpm over resting HR)
• High blood pressure
• Light headedness
• Metallic taste in mouth
• Ring in ears
• Facial numbness
• If beta is blocked increase only BP is seen, not HR

Level of Block testing criteria

If Sympathetic block occurs test for:

• Skin temperature sensation by checking for changes
• Sensory level with a Pin prick by using a sterile needle
• Loss of touch should be only two dermatomes lower than pin prick
• Motor block is measured by Modified Bromage scale of onset of motor Block

Central Neuraxial Blockade preparation

• All equipment, I.V fluids and facilities that mentioned in the preparation to local anesthetic injection should be available
• Assessment, explanation, consent and examination of the patient
• Full asepsis and "no – touch" technique is essential; surgical scrub, gown, mask, gloves,hat, a sterile field
• Equipment should be prepared in advance and in a sterile manner
• A sedative benzodiazepine should often help the patient to tolerate the procedure
• Ketamine at 0.1 – 0.25 mg/ kg can be given when positioning causes pain (such as fractured hip)
• If the patient heavily sedated or ill, he/ she should be positioned in the lateral position with his/her back parallel to the edge of the table and knees and head fixed
• Many anesthetists find the sitting position easier than the lateral position, the patient is placed across the table or bed with their feet resting comfortably on a stool – the spine should be flexed with the chin pressed on to the sternum, and pillow on the knees gives helpful support on the arms

Contraindications to central neuraxial blockade:

Absolute Spinal Anesthesia Contraindications:

• Raised intracranial pressure
• Coagulopathy, blood dyscrasias or full anticoagulant therapy
• Skin sepsis
• Marked spinal deformity
• Hypovolaemia
• Patient refusal

Relative Spinal Anesthesia Contraindications:

• Mildly impaired coagulation: weigh the risk of spinal hematoma against the benefits of avoiding general anesthesia in patients with platelets less than 80,000/mL. If coagulation is impaired, spinal anesthesia is preferred due to lower hematoma risk

Spinal Anesthesia vs Epidural Anesthesia

• Drug delivered to the subarachnoid space and into CSF vs. drug delivered outside the dura
• Injected only below the 3rd lumber vertebra to avoid piercing the spinal cord vs may be given at cervical, thoracic, lumber or sacral sites
• Smaller dose injected vs larger dose injected
• Onset is 2–5 min for initial effect, 20 min max vs. onset is 5–15 minutes for initial effect, 30–45 for maximum effect
• Causes a significant neuromuscular block (muscle relaxation) vs. does not cause significant neuromuscular block
• Gives profound block of all motor and sensory function below the level vs. blocks a band around the injection site
• Almost always a one-shot only vs. an indwelling catheter may be placed for repeated doses

Local Anesthetics

• Many drugs are used for neuraxial block; examples include lidocaine, bupivacaine,levobupivacaine, and ropivacaine.
• Doses change with amount of concentration of the solution, age, body height and weight, type and duration
• Bupivacaine: 0.5 to 2 ml of 0.75% solution for spinal anesthesia, and 10-20 ml of 0.25%, 0.50%, and 0.75% for epidural use

Renal Disease and Anesthesia

• Normal renal function is important for the excretion of anesthetics and medications, maintaining fluid and acid-base balance and regulating hemoglobin levels.
• The kidneys regulate fluid volume/composition, eliminate toxins, and elaborate renin, erythropoietin/Vitamin D
• Factors related to operative procedures and to anesthetic management frequently have a significant impact on kidney physiology/ function like perioperative fluid overload and hypovolemia
• Hypovolemia can cause cute kidney injury, and preop morbidity, extended hospital length of stay, and increased costs
• Kidneys are in the posterior abdominal wall, with the 11th and 12th ribs and diaphragm placed posteriorly, and are 10 cm in length, 5 cm in width, and 3 cm in thickness

Renal Circulation

• Renal function is related to renal blood flow (RBF)
• Blood flow determines oxygen consumption
• Both kidneys have 20% of output
• 80% of RBF goes to cortical nephrons, 10% to juxtamedullary
• Autoregulation of RBF is normally between pressures of 80- and 180-mm Hg
• Glomerular filtration usually stops when mean systemic arterial pressure is less than 40- to 50-mm Hg

Kidney Function

• Regulation of ions, blood volume and blood pH in the blood
• Production of hormones like Calcitriol and Erythropoietin

Waste Excretion

• Urea and creatinine
• Ammonia and amino acid.
• Drugs

Evaluating Kidney Function

• Impaired kidney function may be glomerular dysfunction, tubular dysfunction, or urinary tract obstruction.
• Serum Creatinine can be tested through creatine product of muscle metabolism that is nonenzymatically converted to creatinine and the rate of creatinine production and its volume of distribution is frequently abnormal in the critically ill which can cause Single serum creatinine measurement.

Creatinine Clearance

• Assessment is the most accurate method available for clinically assessing GFR, measurements are usually performed over 24 h, 2-h Creatinine clearances less than 25 mL/min are indicative of overt kidney failure

Effects of Anesthesia & Surgery on Kidney Function

• Acute kidney injury (AKI) is a common and underappreciated perioperative problem, occurring in 1% to 5% of all hospitalized patients and in ~50% of all ICU patients: fluid/electrolyte derangements, respiratory failure, major cardiovascular events, weakened immunocompetence, altered mental status, hepatic dysfunction, and gastrointestinal hemorrhage & a major cause of chronic kidney disease

Increased perioperative AKI Risk Factors

• Preexisting kidney disease
• Hypertension
• Diabetes mellitus
• Liver disease
• Sepsis
• Multiple myeloma
• Age greater than 55 years
• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Radiocontrast agents
• Antibiotics
• There are a few reversible decreases in RBF, GFR, urinary flow, and sodium excretion that occur during both neuraxial and general anesthesia and most changes are indirect autonomic/hormonal responses to anesthesia & risk of AKI when adequate intravascular volume + normal blood pressure are maintained

Chronic Kidney Disease

• Kidney damage or a GFR less than 60 mL/min for 3 months or more
• Oliguria does not a reliable marker of disease fluid overload/cardiac disease and laboratory testing, proteinuria and urinary sediment are helpful in diagnosis

Renal Failure Causes

• Diabetes Mellitus 25%
• Glomerulonephritis 14%
• Hypertension 8%
• Polycystic kidney disease 6%
• Pyelonephritis 6%
• Renal vascular disease 6%
• Others 17%/Uncertain 15%

Systemic Effects

• Cardiovascular system: Left ventricular hypertrophy, Atherosclerosis and hypertension
• Respiratory system: Pulmonary edema; Metabolic acidosis; Coagulopathy
• Autonomic neuropathy and Fluid/electrolyte
• Volume overload
• Hyperkalemia

Altered Kidney Function & Anestaesia

• The pharmacokinetics of both propofol and etomidate are minimally affected by impaired kidney function
• Patients with kidney disease often exhibit increased sensitivity to barbiturates during induction, even though pharmacokinetic profiles appear to be unchanged: increased free circulating barbiturate is caused a a more rapid entry of these agents into the brain
• Ketamine pharmacokinetics are minimally altered by kidney disease
• Increased benzodiazepine sensitivity in patients with hypoalbuminemia: diazepam and midazolam should be administered cautiously in the presence of kidney impairment
• Most opioids used in anesthetic practice are inactivated by the liver
• Remifentanil pharmacokinetics are unaffected by kidney function bc of the use of ester hydrolysis in blood but there will also be significant accumulation of active metabolites
• Accumulation of morphine and meperidine metabolites may worsen respiratory depression and promote seizure

Inhaled VAs and Kidney Patients

• Volatile agents are ideal because they are not dependent on the kidneys for elimination and they have minimal direct effects on kidney blood flow
• Accelerated induction/emergence may be seen in severely anemic patients. Avoid sevoflurane and gas flows under 2 L/min for kidney-diseased patients who undergo lengthy procedures
• Omit or limit the use of nitrous oxide (or air) to maintain an FiO2 of 50% or greater and increase arterial oxygen content which may be justified in less than 7 g/dL
• Succinylcholine can be safely in the absence of hyperkalemia at the time of induction. It should be avoided in patients with serum potassium is known to be increased.

Important Renal Anesthesia Points

• Cisatracurium/Atracurium agents of choice and reduce muscle relaxation, Vecuronium & Rocuronium is eliminated up to 20% through urine
• Pancuronium depends on renal excretion mostly with Neuromuscular function should be closely monitored
• Edrophonium/neostigmine/pyridostigmine needs to be considered with renal excretion as a prime route of elimination

Important Notes on Renal Anesthesia

• Make Routine anesthetic along with special attention made to renal functions
• Hypotension and ischemic heart disease are both commonly see
• Proteinuria and hypoalbuminemia predispose to edema, Urinalysis cheap test to be preformed, Complete count will reveal more information
• Patients prepped with anti-hypertensives, Antibiotics , Routine transfusion is not recommended especially in chronic patients
• Use general with Open/Laparoscopic surgery, positive pressure ventilation

Important Notes on Analgesia

• Rapid sequence intubation is preferred espicially for chronic cases
• Can induce with Intravenous or Inhalatable Propofol is preferable for the fact to metabolization while being independent of kidney function
• Intraoperative is a good choice because Atacurium is metabolized in such manner
• Arteriovenious limb lines are required to manage blood flow and monitor is a must
• Temperature monitoring is required and warming the patient

Hepatic Blood Flow

• Anesthesia with caution because dehydration occurs especially in elders, output has to be 0.5-1 milk/kg/h in dehydration cases.
• Post Op pain relieve is only appropriate through multimodal opoid usage and no other nephrotic agents are suggested.
• Avoid fistula

Liver Disease and Anesthesia

• The liver is a large, complex organ with multiple multi-functions
• It can be a good and safe option for anestethist
• The liver is known to be Largest, weigh 1500 grammes
• Faliciform ligement splits it to L and R
• It has 50-100k Lobes at a good rate

Flow of liver material

• Hepatic areteiral flow is dependent of oxygen demand
• Gastric flow is dependent
• 20% of cardiac is in output
• 30 percent is flow
• 90 percent is oxygen demand

Portal Vein usage

• 70 percent is flow
• 10 percent is oxy demand
• Alter heptaic perfision depending on flow

Liver tests for proper use

• Bilirubin is considered by most sources with 1.5 mg/dL at max value
• Jaundice is present at levels over 3 mg/dL AST/ALT are two important enzyemed test for a liver problem, also tests like Alkaine phophatase are also to be looked after

Protein checks

• Albumin the protein must be at a rate of 3.5-5.5 g/dL

Functioning tests that need liver support are:

• Normal are between at a rate of 47 to 65 mmll
• prothromb time rate shoul be between 11 and 14 seconds.

Liver issues of concern:

• Hepatic integrity like a one lab test overall, tranamisnase should improve with normal hepataic levels

Problems In liver health :

• There are various abnormalities
• obstructive is when disorders affect exrection
• Parenchyma means a hepatictular function
• This can all be devided by function, injury and biliary

PT

• Prothrombin time needs to be with the extrinsic pathway of coagulation, it measures factors
• 1,2,v,7,10 etc
• definciecies causes all sort liver dysfiunction
• Albumin synthezed in the liver, may reflect liver funtion
• test are all damage based

How are high alt/ast levels caused

• tests liver damages however has not relation between leels and degree of damage
• tests with high liver injury suggest intra hepatcic problems

Bilirubin

• tests biliary obstruciton
• various issues will cause it like hemolysis or drugs or other such syndrome etc
• jaunice appears is usually is at 2/3 mg/dl

LIVER-ALP

• it present in the body however is only elvatated when obsturction ,pregnancy or etc occours

HEpaitc isuses/problem

• Liver failure ranging from nausea to coma due to not taking enough, is diagnosed by coagulation
• encepehopthy means due to toxic protien but when not able to do so, gets high ammonia
• these issues consist jaunice and encepth
• common are those where accetimol and hepaitis and overload due to the toxic levels buildup

Liver issuses

• the heporennal gets damage like liver due kidney deahyrdation
• this in turn is like encephalapth with the builds up ammonia
• this has Hematigical changes: anemia issues with issues in bone
• with this liver damage we must find all coauglation factors is the only was to live and synthasize properly
• risks occour but must be in a certain ammount for safety to happen/or if the patient had issues with it

What to invetstigae ?

• find bleeding and anemia in order to help solve all coagulative proper/times.
• always administer k vitamin
• ecg is another option

What is the anesthic approcahe of choice ?

• avoid premdicsiton most cases and use agent of a choice
• to get an effective treatment do these;
  • lower heptaic and blook
  • can lead to prolonge dtime
  • must adminster vitmin k

Analgesia

• all ways follow blood and fluid level must keep eyes and ears up for safety and effectivness
• must make sure pt is warm and and safe to procaend into surgical procedrue

Anesthesia of Orthopedic Surgery:

• The most important points consist Trauma , Muscloskeletal disease ,Rheumetoid arhtrits RA, cardio pulmonary and and Endocrine issues as well

Problems in orthopeodci surgery or high incidence issues

• It is found young patietns having much abmornmalities, and with congenetal the surgery/cardic is limited
• If neurological/muscel are damaged may case hyperkalmia , this may cause cardic arrset
• Touniqute issue are alos a thing where usage may make the patient suffer in some cases
• Pneomonic Tourque creates extremitiy causes blood loss
• The pressure in the artery usually exceeds arterial pressure so a high point is needed and high time rate will cause pain
• With time limit in the surgery the inflation may case potential issues

Hemodynamic change (blood)

• The blood shift happens becuase it gets transferred/shifted inside the patient, can be bad in diasotoic issue related, pain then starts increasing

Trhomoemblesm

• This is a result of being a tourqurte for so long, muscel will be a result of the induced schemia, and will get thromosis
• Prolonged schemia results disfuntion will be result of permanent nerve damage as well will also impact childern
• BONE issue may be cement implants where more blood wil be added and the patient will have issues with trigger platelets, microthormbus with causes cardiovascular issues

HPOXIA (Increased pulmonary shunt )

• Can also cauase Arrthyms with decreased cardic output, can fix by increase o2
• Deep verinous thhrombosis and P.E pulmonary usually cause after surgery, risk increases
• Obestiy more then 60,30 min long will all add up to higher DVT -Use of tourqutes leads a lot

Position

• All postions must be in the best postions but will also casue risk of nereve cell domage as well - the surgeon needs to be slow and steady while make and using force

What type of hip replacement is safe?

• It is best a general spinal pidural which a combo is often used. as will all provide the most efficient care. Aoids effects like general antheisia
• Good early possitional are better

THR can be provided w/ some techniques while the surgery is a general anesthia

• Patient cant toletate a lyijng fla,t or fixed output state like Aortic Stenosis .
• **

Anesthia for lapascopic surgery. intro

• This a procedure visizlae the domian via endoscrope. It all works best when minimizing surigal incision, it is minamilly inasive
• Procsdure minimize pain
• There a limitations to range when moving. Like all types , it also has new complicatiosn that increase on average

How surgical tools work

• A carbine DIXXODE helps create what we see
• this carbon helps more water that is soluble into VS like N2/helim - like A wall ift is used here with copd

Explore IVRA anesthesia's physiological mechanisms, modifications for patients with peripheral vascular disease, and management of complications like perioral numbness and dizziness. Understand contraindications and risks associated with IVRA. Study tourniquet deflation complications and ACLS protocols.