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nu568 vaporizer/posi

QuestionAnswer
goals of positions 1. max surgical exposure 2. allow for access to the patient, vent drugs and monitors. 3. max surgical results to permit rapid return to preop
types of injuries minor skin abrasaion, serious morbidity. eyes, ears, skin, nose, genitalia, muscle, nerves blood vessels
Affects of injury prolongs hospital stay, cost to patient, psych trauma or perminant disablity.
Prevention and liabality can still be liable even all is done. sometimes it cant be avoided. document all standard of care. AANA 68% were CRNA 52% inappropriate standard of care.
pathophys of injury 1. compression soft tissue nere and vascular damage. 2. stretch injury superficial and have long course 3. transection with surgical injury.
most common nerve injury median in anticubital with IV, brachial stretch, femoral stretch
tissue ischemia 1. decrease tissue blood flow 2. despite lack of blood, metabolism continues, making acid 3. NA-K pump fails 4. intracellular Na builds, increased osmotic gradient and edema causing compartment syndrome
compartment syndrome life threating, nerual and vascualr damage. caused by prolonged operative procedure, hypotension, extremeites elavation. body habitus, precipiated by hypoten and leg elevation.
diagnosis and treatment of compartment syndrome if not treated properly neuromuscular damage occurs, Fasciotomoy is definative treatment, untreated tissue necrosis and acute renal failure with myoglobinuria. amputation and death may occur.
perioperative contributing factor to comp synd straps, crutch sirrups, arms board, hard surafaces, length of procedure greater than 4 hours.
anesthetic techniques and comp synd gen Anes, NMB increasing mobility , hypotensive techniques MAP at 50 only for healthy patients. Neuraxial and peripheral blocks, related to technique, hematoma and needle trauma.
body habitus and comp syn over under weight, muscular. Preexisting conditions PVD, smoking, peripheral neuropathy, subclincal ulnar entrapment, thoracic outlet syndrome.
thoracic outlet syndrome brachial plexus at c5 numbness and tingling of arm in certain positions due to narrowing of passage.
Nerve injuries most common are ulnar and brachial plexus in upper extremities and peroneal of the lower extremities.
Brachial plexus breakdown c5, c6,c7,c8,T1, MARMU musculocutaneous, auxilary, radial, median, Ulnar. 5ventral rami-3trunks-3anter/3posterior- 3cords
most difficulr nerve block is musculo-cutaneous
to block the bracial plexus is AKA interscaline block. To do a axialary block might miss some of the brachial plexus nerves.
Thoracic outlet syndrome weakness in 4th and 5th finger, supraclavicular tenderness, elevation of hand, selemonosky triad.
front view of hip nerves femoral, obturator is deep 30degrees. Nerve resection or lithotomy position can damage them
posterior view of hip nerve sciatic nerve which is longest nerve in body
contributing factor of injury positionsing devices: straps lateroral fem cutan of thigh, crutch stirrups can mess with common peroneal nerve, shoulderbraces with steep trendelenburg, arm boards, improperly places axillary rolls
Supine and complications alopecia or occiputal, excessive neck turning ie brachial pllexus, back aches due to lumbarsacral curve abolishment, crossed legs can mess with superficail proneal nerve. heals up, gel pads used, arms tucked or no abduction greater than 90.
Supine position the good min effect on circulation and perfusion of lungs. FRC decreased with from sitting to supine, dec muscle tone to chest, expan of ribs not limited, effects are offset by mechanical vent, hips and knees slighty flexed to increase venous return.
Trendelenburg does not improve CO, abdominal viscera pushes on diaphram decreases stroke volume, compress the lung bases, inreace ICP by elevating venous pressure
prone position compression of inferior vena cava and aorta d/t cephlad displacement of diaphram. Use Jackson table belly is free to breath, mechanical vent may also offset.
turning hear in prone obstruct juglar venous drainage, not recommendin with cerival arthritis, use prone pillow or mayfield headrest.
protect what in prone prominent aspect of face, arms on side or on boards, chest rolls used from clavicle to iliac crest to relieve abd pressure and faciliate venous return.
variation of prone knee-chest, freed abd and chest expansion, limit arm abduction. AKA kneeling position AKA jack knife position (spine lumbar spine)
Lateral decubitus significant circulatory and vent effects during mechanical vent. compression of vena cava esp with use of kidney rest.
lateral decubitus ie on your side and lungs dependent weighed down and under ventilated, non depend overvent due to increased compliance
VQ mismatch in lateral debubitus underventilated dependent lung has increased pulmonary flow, manifest in arterial hypoxemia.
positioning of lateral axillary roll, radial artery checked, pulse ox on dependent hand, pillow for netrual head, legs flexed with pillow between knees, non dep arm can be elevated on lateral arm rest
sitting position true at 90deg, modified at 45, CV decreased CO, CVP and PAWP. MAP decreases 0.75mmHg per cm of elevation. less effect on lungs,
most complication of sitting position VAE-venous air embolism. negative pressure gradient between right atrium and veins at operative site.
VAE left lateral postion, flood field, pre cordial stethoscope hears a mill-wheel murmur
Lithotomy position vent similar to supine causes cephalad displacement of diaphram by abd viscera. Combined with trendelenberg decreases FRC even further.
lithotomy position increases gastric pressure should be less than 15 max of 20. 20 or more vent becomes more difficult.
pts with these issues are asked to assume the lithotomy position hx of back and lumbar disease. injuries to peripheral nerves sciatic, common peroneal femoral saphenous and obtruartor are at danger.
positioning in lithotomy propper padding between leg braces, boths legs moved up and down together at the same time, min decreased venous return. thighs no more than 90deg before moving laterally, greater than 4 hours in lithotomy results in compartment syndrome.
bp and lithiotomy post op drop in BP seen after legs are brought down.
if peripheral nerve injury happens seek neurology consult, nerve conduction velocity and EMG studies, acute injury will appear 18 to 21 days after onset symptoms. early testing rule out preexisting injury. test both extremities. recovery 3-12 months pain some injuries are irreversible
Ulnar nerve injury most common post op neuropathy. 0.5% of cases, after cardiac is 38% due to surgical retractor
Ulnar nerve passes along the anterior asped of medial head of tricep, posterior into the groove of epicondyle of the humorous and olecranon.
ulnar nerve prevention bending elbow narrow the cubital tunnel and compress ulnar, calsping hands on abd causes supination of hand and roating the humoroous. should rest of arm boards less than 90deg and forearms supinated palms up. pronation of forarme increases injury.
symptoms of ulnar injury inability to abduct or oppose fifth finger. diminshed sensation ver both surfaces, Claw hand. eventual atrophy of hand.
brachial plexus C5-T1, second most common injury. stretch and compression injury. stretch neck over extended or arm abducted greater than 90. compression between clavical and first rib when should braces are not placed over the acromiocalvicular joint.
causes of brachial plexus shoulder straps, first rib fx, lateral decub poistion due to arm abduction than 90deg. sternal retractors move clavicle move posteriorly. stinger or burner syndrome.
Brachial plexus injury prevention avoid excessive or prolonged retraction when possible. do not abduct greater than 90, prone patients arms should be over head bent at elbow and abducted less than 90. keep head and neck alignment. axcilarry roll but not under acilla.
Radial Nerve injury if arm slips off table or is at edge for long time. pressure from distal edge of mechanial BP cuff.
symptoms of radial nerve injury wrist drop, weakness of abduction of thumb, decreased sensation over dorsal surface of later three and half fingers.
radial nerve dorsal back of thumb back of 2nd and 3rd finger
median nerve run along anticubital fossa
Median nerve injury due to IV placement or extravasation of drugs like thiopental. opposition and flexion of thumb lost. thumb and index fingers arrested in adduction and hyperextension. Ape hand deformity. decreased sensation on palmer surface of lateral three and one half finger.
sciatic nerve compression may occur as nerve passes the piriformis muscle. stretch injury during fixation of nerve increased with external roation or extension of knee.
fixation of sciatic nerve is sciatic notch and fibula
properties of sciatic nerve longest and widest single nerve, branches are tibial and common peroneal (next to fibula of knee)
causes of sciatic nerve injury improperly positioned in lithotomy, min stretch so external rotation of leg is min knees should be flexed. IM injection to buttocks could cause injury. IM should be in lateral aspect of thigh.
sciatic nerve injury manifestation weakness of all skeletal muscle below knee, diminished sensation of lateral half of leg almost all of foot.
common peroneal nerve a branch of sciatic nerve which is frequently damaged in lower extremity. compression of head of fibular and metal brace in lithotomy. check candy cain
common peroneal manifestation foot drop, loss of dorsal extension or toes, inability to evert(turn) foot.
Anterior tibial nerve foot drop post op if feel are plantar flexed for extended time. should have rolls under anterior aspect of ankle to maintain extended position
femoral nerve injury compressed at pelvic brim by self retaining retractor during laparotomy or excessive angulation of thigh when in lithotomy.
femoral injury symptoms decrease knee jerk, loss of flexion of ip and extension of knee as result of quadricep femoris injury. sensation over superior thigh medial and anterior thigh absent to decreased.
saphenous nerve branch of femoral nerve, compression against medial tibial condyle if foot is suspended lateral to vertical brace. medial knee and leg pain with walking or standing for long time.
saphenous nerve location above knee tibial side
peroneal nerve location above or at knee on fibula side
sural cutaneous nerve location below the peroneal nerve on fibula.
obturator nerve location and manifestation right behind femoral nerve, inability to adduct legs and decrease sensation over medial side of thigh. excessive flexion of thigh to groin.
non neural injury skin, eyes, appendages
skin injuries pressure, ischemia, may need grafts, ulceration at corner of mouth ETT, groin necrosis due to positioning for hip surgery.
postoperative visual loss rare but devestating. 0.02%, higher in cardiac and prone spine surgery. more prone spine. retina supply axon to optice nerve and brain.
optic nerve extends from globe to optic chiasm divided to 4 sections: intraocular, intraorbital, intracannilicular, intracranial.
retina and optic nerve blood supply through the central retinal artery and long and short posterior cialiary arteries that arrive from internal carotid. prone and hypotension puts pt at greater risks.
post operative visual loss these arteries lack autoregulation in event of hypo-perfusion
Preexisting/conditions conditions that effect autoregulation diabetes, hypertension makes pts more susceptible. head rest in prone, thrombosis of central retinal artery with perminant blindness, deliberate or accidental hypotension, IOP increased
Appendage damage fingers or toes when surgical table moves, trauma most likely to finger with foot of bed returning horizontal fro lithiotomy (pinch) ears, if pinched on table or mattress.
damage related to mask 1.perm hair loss to outer third of eyebrow. gauze prevent. 2.buccal brach of facial nerve ie no more whistle or kiss motion. 3. necrosis of bridge of nose, remove.
4. suborbital from nasal ETT 5. facial nerve compression of fingers with asceding ramus of pt mandible.
vaporization vapor is gasous state of liquid
gas substance in gaseous state under standard pressure and temp
rate of vaporization depends on temp, vapor pressure of liquid, partial pressure of vapor above evaporating liquid
William Henry Law conc of dissolved gas depend on partial pressure of gas, partial pressure controls number of gas mol collisions with surface of solution. with partial pressure doubled then collisions double. increased collsion more dissolved gas.
Latent heat of vaporization heat needed to change liquid to vapor
Latent heat of vaporization of 1g of water at 1atm 540calories,
Endothermic absorbs energy from solid to liquid to gas
exothermic release energy and heat
vapor pressure molecules of volatile in closed container are distributed between liquid and gas. gas mol bounce off container making vapor pressure.
Vapor pressure and temp higher temp higher tendancy of liquid to gas
vaporization requires energy, temp of liquid drops and vaporization decreases, surrounding temp also drops. making ice crystal
early vaporization chronology open drop ether, water baths no way to measure concentration delivered. then copper kettle, agent specific vap, and heated vapor
anesthetic output calibbration=
copper kettle utilized two gas sources carrier and dilutent, first to be concen measured
copper kettle why use it? relatively high specific heat, heat required to raise the temp of 1g by one deg C, thermal conductivity, maintain constant temp, use carrier and dilutent gas
vapor pressure of volatiles halothane 243, isoflurane is 240, sevo 160, desflurane 681 all are at 20deg C. Des boiling point is 23degC 1atm= 760mmHg
copper kettle and vernitrol are not agent specific
Measured flow or vernitrol vaporizer utilized in military, similar to copper, if it cools new calc needed, unit is out of circuit. not agent specific.
Vaporization rate of vaporization depends on temp, VP, and partial pressure of vapor above evaporation liquid
Variable bypass vaporizor small fresh gas flow, flow over. safer method, temp compensated.
type of variable bypass, flow over vaporizer TECH 4, 5, 7 Splitting ratio: gas entering the vaporizer chamber diveded by total gas flow. auto determined by internal resistance to flow. higher setting is higher gas through vaporizer chamber called chamber flow or carrier gas.
chamber flow or carrier gas gas send through the vaporizing chamber, increased as the dial is set higher.
Tech4 has wicks and baffles esure full saturation of carrier gas. diluted with fresh gas bypassed the vaporizing chamber. this mix makes final concentration.
temp compensating valve brass zinc mixture: bimetalic strip
Modern vaporizers major characteristic agent specific, constatnt vapor concentration regardless of temp pressure or gas flow through vaporizer. fractionalizes gas flow ie variable bypass. out of circut vaporizer ie gas is not recirculated through vaporizer no condensation
modern vaporizers gas delivery delivered conc may be diluted by O2 or N2O. change of conc in circut depends on fresh gas flow, high gas flow achieves equilibrium faster ie overpressure
safety in modern vaporizers operator can dial only one gas at a time due to interlock system. keyfilled, site glass for filling status, overfilling may hurt patient.
all variable bypass vaporizers must be turned off prior to filling not true, the Desflurane tech 6 can be filled while in use less at 8L and 8%.
Sevoflurane at high fresh gas flow tend to be less accurate, end up delievering less than dial setting. due to low VP, this effect is accentuated when almost empty. ie it wont run properly.
tech6 for desflurane needs to be plugged in with heating element. without heat the overcooling of agent stops it from working. only one that delivers in Volume %
Tech 6 heated to 39C or 102 F to 2atm.
Celcius= 1.8(F) +32
tech 6 for desflurane mechanism of action freshgas does NOT flow over liquid. vapor is added to FGF. First circuit point controlled by concentraion dial. Point2 is transducer responds to amoutof FGF
Tech6 to deliver more anestheritc vapor increase the concentration dial or FGF. Second circuit heats to 39C VP equals 1500mmHg,
Desflurane in a variable bypass would constitute a 100% putput and hypoxic mixture will result.
battery safety check of tech6 battery, turn on1% and unplug. in 15 seconds and no output light and alarm should activate if battery needs to be replaced.
Tech6 no output alarm tilting device over 10Deg, power failure longer than 10 seconds, internala malfunction, if this occurs then change to different gas IMMEDIATELY or else pt wakes up very quickly.
Drager Vapor 19 is tipple, fits with interlock system . if removed then a block must be added to prevent leak. all modern vaporizer turn up counter clockwise. T setting for transport or tipping (not for long)
Datex omeda ADU vaporizer are tippable are cassets with control wheel on left hand side.
Hazzards of contemp vaporizers why wont work right almost impossible but can be filled with wrong agent. , if tipped over 45deg, must be serviced, otherise unpredicable to use. do not overfill, may decaliberate. , may be hung wrong, mising gasket, ADU covered with vomit do not work
Key lock filler system agent specific. one to bottle one to vaporizer. specific collar with each agent to vaporizer.
pumping effect cause intermittent back pressure of transmitted from the breathing circuit. or use of oxygen flush valve. increases vaporizer output. check valves between the vaporizer and common gas outlet. reduction of vap chamber and baffle almost immune to pumping.
what helps reduce pumping effect wicks, baffles, check valves, channels. pumping generally increases vaporizer output.
pressurizing effect carrier gas is compressed due to pressure applied, increasing concentration of carrier gas. ie less vapor and more FGF, decrease in vaporizer output. Does not happen with open system.
low flow anesthesia prolongs induction, used for mantance save flow, save money, does not save CO2 absorber. Induction howerver, overpressure example 18% Desflurane.
1ml of liquid volatile= 200ml of Gas vapor.
anesthetic wash in requires both fresh gas and concenctration of agent.
Low flow maintained at 1to 2 L/min after equilibrium. this concerves heat and humidity gas and agent.
Emergence occurs with high flow and no gas
CO2 absorber allows for rebreathing system to occur, conserving agent, gas and humidity. prevent acidosis, low flow of 0.3 to 0.5L/min in circle system provide near total rebreathing with co2 absover.
High flow 5 to 8L/min and CO2 absorber rely little on CO2 absorber, the CO2 is rapidly diluted and scavenged at these flow.
CO2 absorber Ionic reaction on surface of soda-lime, 10-20% water content speeds the efficiency. dry granules exhaust faster, may contain NaOH or KOH strong bases to increase reation
NaOH and KOH with carbonate ions or CO2 in reversible reaction that yields water and heat. one mole of CO2 produces 13,000Kcal of heat
Ethyl violet dye added to soda lime, serves as pH indicator, critical at 10.3 starts at 14, colorless to blue/purple.
compound A sevo and sodalime no good. lethal at 130-340ppm or renal injur at 25-50ppm in rats. in human comparable to des. flow of 2L required for MAC of 2 hours.
carbon monoxide and VA Des>enflurane>Iso. Halothane = sevo. worse in dry absorber.
CO2 absorber Purpose recieve exhaled gas from pt, neutralize CO2, neutralize gas given back to pt.
channeling and co2 absorber produces a channel with least path of resistance. makes absorber much less efficient. same as wall effect.
stacked series of CO2 absorber top does most of work, bottom to top and and new one placed on bottom.
CO2 and water on surface of hygroscopic granules yields carbonic acid. H2CO3. if you add water you create Alkaline water, dangerous to pt.
baralyme not in use anymore. causes fire, degrades agents, reduce efficiency.
H2CO3 carbonic acid reacts with base making neutral salt. exhaled gases are then inhaled by pt without CO2.
Sodalime bases calcium hydroxide94% NaOH 5% and KOH 1%. Ca and K with desiccated absorbent makes CO and other toxins. Na and K speed up rx. Silica added as hardener. Prevent dust.
CO2 on market carbolime, Amsorb, dragersorb 800plus, drager sorb free
CO2 price comp A , CO with strong bases K or NaOH. OR fire sevo and baralyme implicated.
CO2 energy 1mole of CO2 makes 13000Kcal, exothermic RX, soda lime does not Regen, does not matter if color goes back
CO2 + H2O H2CO3 carbonic acid 1st neutralization
H2CO3+NaOH Na2CO3 soda ash (tide) + H2O + energy (exothermic)
NaCO3 + Ca(OH)2 CaCO3 decreases+NaOH second neutralization. NaOH is regeneration of activator.
compound A an ethyl methyl ether produced in desiccated or nondesiccated. in presence of Sevo only. NOT an issue in humans. Danger level, 130ppm, renal injury 25-50ppm. 2L FGF for MAC of 2 or more hours.
CO and baralyme CO make with deiccated baralyme, strong bases KOH and NaOH have been implicated. Desflurane most susecptable to CO formation with desiccated granules.
early signs of CO2 exhaustion resp acidosis, sympathetic nervous system activation(flush, cardiac irregularities, sweating.) Partial pressure of end tidal CO2 increased CO2 inhalation.
Late sign of CO2 exhaustion increase then later decrease of HR and BP, dysrhythmia.
CO2 absorber contains 1Kg of granules 1500ml volume. each 100g absorbes 15L of CO2. avg adult makes 15L perhour. what is the lifepsan of one canister. 10 hours per container.
CO2 should be changed every 48 hours, every monday, shake canister to settle so no wall or channel effect.
advantage of circle system economy of agent, warming, humidifcation of gases. advanced scavenging reduces enviromental pollution.
disadvantage of circle system costly, bulky, co2 absorber and one way valves increase resistance to breathing. CO2 abs dust, anesthetic level change slowly with low flow anesthesia.
release pressure check of the APL valve not through the elbow but by opening the APL valve. reduces dust.
capnorgraphy AB is baseling, BC expiraroty upslope, CD expirartoy plateau. D end tidal value.
if base line on capnorgraphy is not coming back CO2 rebreathing might be happening.
incompetent inpiratory valve cirlce will have no return to baseline and back slash down slope.
pop off closed barotrauma, or not enough gas, need less fgf, rapid co2 drying may make toxins: compA, CO, methanol, formaldehyde
Halothane 0,75MAC=5.7mmHg partial pressure
Isoflurane MAC 1.15MAC=8.7mmHg partial pressure
Desflurane MAC 6-7.25MAC= 46-55mmHg partial pressure
Sevoflorane MAC 2.1MAC=16mmHg partial pressure
Agent Partial Pressure= MACx760/100

Created by: Rooz