ENT and Ophthalmic Surgeries Lesson 1 PDF

[ENT Anesthesia] - Special considerations - Shared airway with surgeon - Pt is positioned 90-180 degrees away from anesthesia - Ensure ETT is secure and check after repositioning - Pay attention to IV lines - Controlled/permissive hypotension -...

[ENT Anesthesia] - Special considerations - Shared airway with surgeon - Pt is positioned 90-180 degrees away from anesthesia - Ensure ETT is secure and check after repositioning - Pay attention to IV lines - Controlled/permissive hypotension - MAP is reduced to reduce bleeding and improve surgical visualization - MAP is usually reduced 20% from baseline - Requires a-line - Chronic HTN pts may require higher MAP due to shifted autoregulatory curve - Monitor UO, MAP, CPP, ABGs, cardiac perfusion - Methods = inhalation agents, vasodilating agents, beta blockers, alpha-2 agonists, calcium channel blockers, ultra-short acting opioids, mag sulfate - ENT procedures are associated with a higher incidence of PONV - Local anesthetics - Cocaine= anesthetic and vasoconstrictive properties - Blocks reuptake of NE and epi at adrenergic nerve endings - Causes sympathetic stimulation so use with caution in CV disease s - Lidocaine = rapid acting and can be used in all areas of tracheobronchial tree - Benzocaine = short duration; can produce methemoglobinemia - Methemoglobinemia will show on the pulse ox as an SPO2 that approaches 85% no matter what - Bupivacaine = longer duration due to slow hepatic clearance - Mepivacaine = rapid acting, intermediate potency - Anticholinergics - Antisialagougue used to dry upper airway and reduce secretions - Atropine - Scopolamine - Less likely to increase HR - More often used for PONV due to slow onset - Glycopyrrolate - Less tachycardia - Does not cross BBB and no sedative effects - Longer duration of action - Corticosteroids - Used to decrease laryngeal edema and PONV - Prolong analgesic effects of LA due to inhibition of prostaglandin synthesis - Administer as early as possible - Vasoactive drugs - Used to minimize intraoperative blood loss and optimize visualization - Prolong effects of LA - E.g. cocaine, epi containing LA, oxymetazoline - MLT = micro laryngeal tubes - Smaller diameter, longer length - Have adult sized cuff located further away from the tube tip - Come in size 4,5, and 6 - Preformed RAE tubes - Have a preformed bend and no stylet for placement - Oral RAE (south facing) - Nasal RAE (north facing) - Reinforced/armored tubes - Have embedded coil for stability to provide increased flexibility and resistance to kinking - Good for procedures with neck flexion or where severe angles of ETT are required - Not intended for pts that remain intubated post-op - Can be easily occluded if pt bites down so place a bite block on emergence - NIM tube - Allows intraop monitoring of laryngeal muscles - Precision required for placement -- need glidescope - Not intended for pts that remain intubated post-op - Laser tube - Laser resistant and should be used for all airway laser procedures - Pilot balloon should be filled with saline mixed with methylene blue - Laser resistant tubes are not laser proof! - LMA - May be indicated in select procedures - Less tracheal stimulation than ETT - Less coughing on emergence - NMBAs not required - Can also be used for airway rescue scenarios - Provides conduit for surgical access to trachea and glottis - Isolates glottis from bleeding in pharynx - Throat pack is placed by surgeon to prevent secretions from falling into aiway - Airway management -- Ventilation - Standard intubation = Use smaller ETT or MLT - Intermittent apnea = Alternating periods of ventilation and apnea while the surgeon works - ETT can be removed and reinserted - Advantages = no special equipment - Disadvantages = potential inability to reintubate, CV lability - Insufflation (tracheal gas insufflation) - Used in laryngeal procedures - Smaller catheter introduced into the nasopharynx and placed above laryngeal opening - Can also use the side arm channel of the laryngoscope or bronchoscope to ventilate - Jet ventilation - No ETT/intubation required - Can be performed supraglottic, infraglottic, transtracheal, or via bronchoscope - No absolute contraindications except full stomach, trauma, or hiatal hernia - Delivers 60 psi on inhalation while exhalation is passive - Need to allow sufficient exhalation time to avoid air trapping, barotrauma, hypercarbia - Can be difficult to maintain adequate oxygenation and CO2 elimination in some patients (morbid obesity, stiff thorax, advanced restrictive ad/or obstructive lung disease, pulmonary edema) - No scavenging -- environmental concern - THRIVE = transnasal humidified rapid-insufflation ventilatory exchange - Nasal high flow can be used in spontaneously breathing or apneic pts - Spontaneously breathing use = high FiO2, positive airway pressure promotes pharyngeal dead space washout and improves respiratory mechanics - Apneic use = highly turbulent supraglottic flow vortices and cardiogenic oscillations extends the apneic time before desaturation better than low-flow apneic ventilation - Laser= light amplification by stimulated emission of radiation - Characteristics - Monochromatic = one wavelength - Coherent = oscillates in the same phase - Collimated =exists as a narrow parallel beam - Advantages = surgical precision, hemostasis, less postop edema and pain - Wavelength is determined by the medium used - Increased wavelength = increased water absorption = decreased tissue penetration - Decreased wavelength = decreased water absorption = increased tissue penetration - Wavelength determines function - Types of mediums = type of laser e.g. Co2 laser, Ho:YAG, argon - Lasers used in ENT procedures = CO2 and Ho:YAG most commonly used - CO2 used in and around the larynx due to shallow depth of burn and extreme precision - Ho:YAG used for nasal surgery and tonsillectomies - Use of specialty glasses and cover OR windows during use - Respiratory mask for personnel - Prevent airway fire! - Minimize FiO2 (21% ) - Avoid nitrous oxide (supports combustion) - Laser-resistant and well-sealed ETT (2nd cuff with saline +/- methylene blue) - Limit laser intensity and duration - Saline-soaked pledgets in airway - AVAILABLE FIRE EXTINGUISHER! - Let prep solutions dry for at least 3 mins - Surgical fire - Triad of fire = ignition source, fuel, oxidizer - Common fuels in the OR = hair, tissue, alcohol preps, dressings, drapes - Silverstein fire risk assessment - Surgery above the xiphoid? - Open oxygen source? - Available ignition source? - Fire risk 1 = low risk so standard precautions - Fire risk 2 = low risk with potential to convert to high risk - Fire risk 3 = high risk - Use high flow, low FiO2 - Stop supplemental oxygen at least 1 min before and while using cautery - Use wet sponges - Keep syringe full of saline available for procedures in the oral cavity - Signs of fire = darkening of ETT or circuit with soot, orange/red glow to ETT - ETT will act like a blow torch during an airway fire - Actions in the event of an airway fire - Stop vent and remove ETT simultaneously - Turn off oxygen and disconnect circuit remove burning material from airway - Pour saline in airway - Ventilate and reintubate - Assess for damage - Consider bronchial lavage and steroids - Endoscopic procedures - E.g. laryngoscopy, panendoscopy, esophagoscopy, bronchoscopy - Preop eval = assess for airway problems - Use caution with routine premeds - Need profound muscle relaxation with rapid recovery - Procedures are very stimulating so one way to manage is to use baseline anesthetic e.g. gas with intermittent boluses - BMT (bilateral myringotomy tubes) i.e. ear tubes - Seen in pts with chronic otitis media, frequent URI - Preop eval for current URI - Ultrashort procedure - Mask induction - No IV - Have airway equipment always available - Turn off inhalation agent when starting second ear and use N2O at case completion - Avoid preop sedatives because they may outlast the procedure - N2O can be used for this procedure because its short and the tubes allow egress of gas. This is unique because N2O isn't typically used in ear procedures - Chest symptoms and active fever is a reason to postpone case - Tonsillectomy and adenoidectomy - Seen in pts with OSA, cardiac and respiratory anomalies, speech and swallowing disorders - Preop eval for URI and sleep disordered breathing (STUBR = Snoring, Trouble Breathing, UnRefreshed after sleep) - Peds - Inhalation induction - Cuffed tube if 8 or older - Per Dr. S -- she uses cuffed tubes on all pts - Want air leak of at least 20 cm of H2O - Adults - IV induction with balanced technique - Complications - Bleeding 6 hours/6 days - Laryngospasm - Bronchospasm - PONV - Emergence - Decompress stomach via OGT - PACU in tonsil position - Post-tonsillectomy hemorrhage = surgical emergency - Most common pediatric airway emergency - Risk factors = age \>15, frequent tonsillitis, hot cautery - Pt is a full stomach due to swallowing blood so RSI - DO NOT suction stomach prior to induction because this can dislodge clots - OGT of stomach after airway is secured - Awake extubation - Cleft palate and cleft lip - Often associated with other surgical anomalies - Surgical repair is performed in phased procedures - Rule of 10 to be optimized for this surgery = weight 10kg, Hgb \>10, WBC \10 weeks - Intubation can be difficult -- don't let blade slip in cleft - Use Oral RAE with flexible connector - Secure ETT at midline of lower lip - Tip of tongue sutured to cheek before emergence -- NO oral airway - Slight tension on suture resolves airway obstruction - Postop logan bow apparatus will make mask ventilation difficult or impossible - Thyroid gland - Largest endocrine gland in the body that is involved in the synthesis, storage, and secretion of thyroid hormones - RLN and external branch of the SLN lie close to the lateral lobes of the thyroid - Thyroidectomy - Often associated with hyperthyroidism, thyroid goiter, malignancy - Preop eval = assess for airway problems and thyroid hormone levels - Continue thyroid meds and beta-blockers - Pt should be euthyroid preop - Management = GA ETT with or without cervical plexus block and possible nerve monitoring - Use direct-acting vasopressor over indirect acting (phenyl preferred over ephedrine) - Position = supine with HOB elevated 30 degrees and neck extended - Consider steroid supplementation - Postop monitor for hypocalcemia 24-96 hours postop and nerve injury - Unilateral RLN injury = hoarseness but no respiratory distress - Bilateral RLN injury = respiratory distress due to unopposed abduction - External branch of SLN injury = impaired pitch and voice fatiguability - Postop hematoma = airway emergency that may require reintubation - Parathyroidectomy - Calcium levels are regulated by PTH - Anesthetic management is similar to thyroidectomy with the addition of intraoperative monitoring of calcium levels - Signs and symptoms of acute hypocalcemia = laryngospasm, bronchospasm, prolonged QT, circumoral numbness, distal extremity numbness, confusion, seizure, Chvostek sign, Trousseau sign - Cancer/radical neck dissection e.g. laryngectomy, glossectomy, pharyngectomy, hemi mandibulectomy, radical neck dissection - Typical pt is older with a hx of smoking, ETOH use, bronchitis, emphysema, CV disease - Can be due to HPV - Preop assess for airway patency and nerve monitoring - Intraop - Lengthy procedure with risk for blood loss -- get type and cross - Supine position with arms tucked and HOB elevated - Manipulation of carotid sinus and stellate ganglion can cause wide BP and HR variation - Surgeon can use LA infiltration to mitigate - Moderate controlled hypotension - Free flap = area of skin used for skin grafting - Following free flap, maintain BP, minimize vasoconstrictors/dilators, avoid excess diuresis - Emergence - Assess of RLN and SLN injury - Bilateral neck dissection can result in postop hypotension and loss of hypoxic drive due to denervation of carotid sinus and bodies - Monitor for hypocalcemia due to acute hypoparathyroidism due to unintentional removal of parathyroid glands - Tracheostomy - Preoxygenate unless surgeon is using electrocautery to enter trachea. If so, FiO2 30% or less - Suction trachea to limit aspiration - Deflate ETT prior to tracheal transection by surgeon - During tracheal transection, pull ETT back to level just above tracheal incision - Ventilation is difficult due to large tracheal leak - Placement verified before ETT is removed from mouth - Complications = bleeding, SQ emphysema, mediastinal emphysema, airway obstruction, pneumothorax - Laryngectomy - Total = removal of hyoid bone, entire larynx (including epiglottis, false cords, true cords), cricoid cartilage, 2-3 tracheal rings - Requires tracheostomy postop to ventilate - Supraglottic or horizontal laryngectomy = removal or hyoid bone, epiglottis, false cords - May aspirate easily - Vertical or hemi-laryngectomy = removal of one true cord, false cord, arytenoid cartilage half of thyroid cartilage - Partial laryngectomy = removal of one vocal cord - Hoarse voice - Endoscopic removal of early carcinoma = removal of one part of vocal cord - You're called to the unit to manage a patient with a tracheostomy but the nurses can't ventilate. What do you do? - Use existing stoma to manage airway - DO NOT try to intubate through nose or mouth - Ear procedures - Stapedotomy = surgical creation of a small hole in the stapes - Tympanoplasty = reconstruction of tympanic membrane - Mastoidectomy = removal of mastoid bone due to infection or for a cochlear implant - Anesthetic implications - No nitrous - Facial nerve monitoring so no muscle relaxants - Hemostasis - PONV and postop vertigo - Facial trauma - Le Fort Classifications - No nasal instrumentation for Le Fort 2 and 3 - If you are concerned about the airway -- tracheostomy under local or awake intubation - Planned intermaxillary fixation = nasal tube - Awake extubation with airway reflexes intact - Want wire cutters at bedside at all times - Innervation of the nose - Anterior ethmoidal nerve - Sphenopalatine nerve - Sinus and nasal procedures e.g. polypectomy, maxillary sinusotomy, rhinoplasty, septoplasty - Assess for difficulty mask ventilating - Anticipate need for oral airway due to nasal obstruction - Use reinforced or RAE ETT - Vasoconstriction - Prevent corneal abrasion - During endoscopic sinus surgery, one eye remains untaped - Muscle relaxation required due to close proximity to brain and eye - Posterior pharyngeal pack - Extubation -- awake vs deep - Foreign body aspiration and rigid bronchoscopy - Common site of foreign body is right bronchus - Supine during aspiration = right upper lobe - Standing during aspiration = right lower lobe - Signs and symptoms = wheezing, choking, coughing tachycardia, aphonia, cyanosis - Anesthetic implications - Keep pt breathing spontaneously - Anticipate laryngeal edema - Prepare for emergency cric or tracheostomy - Hypoxic cardiac arrest can occur during item retrieval - Avoid coughing or bucking - Check for edema before extubation [Ophthalmic Procedures ] - Eye structures - Iris regulates the amount of light that enters the eye via dilation and constriction - Pupil is the circular opening in the center of the iris - Cornea refracts light entering the eye onto the lens - Contains no blood vessels - Sensitive to pain - Choroid is the middle layer of the eye between the retina and the sclera - Lens is the transparent structure behind the pupil that refracts incoming light - Retina is comprised of light sensitive cells (rods and cones) - Macula is the yellow spot on the retina at the back of the eye - Eye muscles - SR = superior rectus moves the eye up i.e. supraducts - MR = medial rectus = adducts the eye - LR = lateral rectus = abducts the eye - SO = superior oblique = rotates the eye towards the nose i.e. intorts - IO = interior oblique = rotates eye towards temple i.e. extorts - Innervation of eye - LR6, SO4, R3 = Lateral rectus is CN 6, superior oblique is CN4, rest are all CN3 - Optic nerve - Senses incoming light and transmits to cerebral cortex - Works with oculomotor nerve to change pupil size - Oculomotor nerve (CN3) = motor innervation to most of the extraocular muscles; constriction/dilation (miosis/mydriasis) of the pupils - Trochlear nerve (CN4) = innervates superior oblique - Trigeminal nerve - 3 branches - Only ophthalmic branch innervates eye and serves as the afferent branch of corneal and lacrimation reflex - Abducens nerve (CN6) = innervates lateral rectus - Facial nerve = motor innervation of the orbicularis oculi muscle which controls eye closure and blinking - Vagus nerve = efferent limb of oculocardiac reflex - Oculocardiac reflex = 5 and dime reflex = Ascher phenomenon - Decrease in HR by 20% after traction to extraocular muscles and/or eyeball compression - Afferent limb = trigeminal - Efferent limb = vagal - Can occur with local infiltration of LA, retrobulbar block, and peribulbar block - Can occur during GA - Causes dysrhythmias e.g. bradycardia, AV block, PVCs, idioventricular rhythms, asystole, v fib - Almost completely abolished by atropine but routine prophylaxis is controversial - Most common in pediatric strabismus repair - Treatment - Stop stimulus - Confirm adequate ventilation, oxygenation, and anesthesia - IV anticholinergic is HR doesn't recover with cessation of stimulus - Infiltration of LA into rectus muscles - Repeated stimulation eventually fatigues the stimulus - Intraocular pressure = fluid pressure of the eye - Determined by aqueous humor (fluid between the lens and cornea) - Aqueous humor is produced by the ciliary epithelium in the posterior chamber - flows through the pupil into the anterior chamber - exits anterior chamber via the canal of Schlemm - Goldman equation = IOP = (F/C)+P - F = aqueous inflow - C = aqueous outflow - P = episcleral venous pressure - Normal IOP = 12-20 mmHg - Transient increases during blinking - Anything that increases venous pressure increases IOP e.g. intubation, hypercarbia, airway obstruction, hypoxia, coughing, t-berg position - Agents that reduce IOP = inhalation agents including nitrous oxide, propofol, benzos, opioids - NDNMBDs will have no effect or decrease - Succinylcholine will increase IOP 5-10 mmHg in 5-10 mins - Previously contraindicated in open glob injuries - Glaucoma - Medications = mydriatics or miotics - Mydriatics cause direct or indirect effect on dilator muscles of iris - Alpha-2 agonists reduce aqueous humor production - Contraindicated with MAOI - Cyclopegics cause temporary paralysis of ciliary muscle and muscles of accommodation - Can cause systemic HTN - Miotics = cholinergic agonists - Can cause bradycardia, bronchospasm - Glaucoma meds = alpha-2 agonists, cholinesterase inhibitors, beta blockers - Alpha-2 agonists reduce aqueous humor production - Contraindicated with MAOI - Cholinesterase inhibitors improve outflow of aqueous humor, produce mioisis, reduce plasma cholinesterase, inhibit metabolism of LA - May prolong effects of succs and esters LA - Beta blockers reduce aqueous humor production - Carbonic anhydrase inhibitors reduce aqueous humor production. Check electrolytes preop - Prostaglandins promote outflow of aqueous humor - Intraocular gas expansion - Used during retinal detachment surgery to flatten a detached retina and facilitate healing - N2O must be discontinued 15-30 mins prior to the bubble being placed - If pt returns to OR, avoid N2O until the gas bubble is fully absorbed - Anesthetic considerations for eye surgeries - Short procedures but immobility is required - PONV prophylaxis - Table will be turned away from CRNA - MAC/Regional - Not appropriate for posterior chamber procedures - LA used tetracaine 0.5% and lidocaine 2-4% - For cataract surgery 1 mg of versed and 50 mcg of fentanyl is adequate for most patients - Regional blocks - Goal is to anesthetize CN 3, 4, 5, 6, 7 - Medications used for sedation = midazolam, fentanyl, propofol - Retrobulbar block (RBB) - Provides akinesia, anesthesia, and abolishment of oculocardiac reflex - Technique - \#25g retrobulbar (dull) needle is inserted into the retrobulbar space - After negative aspiration 2-4 ml of local anesthetic is injected - Complications = trauma to optic nerve, blood vessels, globe, vision loss, intravascular injection - Peribulbar block (PBB) - Onset is delayed and may not obtain akinesia - Medial peribulbar approach is best for eyelid akinesia - Sub-tenon/episcleral block - Tenon's fascia surrounds the globe - LA injected into subscleral space between Tenon's fascia - Uses special blunt curved cannula - Fewer side effects compared to RBB and PBB - Facial nerve block - Utilized when akinesis of the eyelids is desired - Disadvantages = pt discomfort and proximity to eye - Proximal = O'Brien technique, Nadbath technique - Causes unilateral facial paralysis - Nadbath technique not recommended due to close proximity to glossopharyngeal nerve and vagus nerve - Distal - VanLint technique blocks zygomatic and temporal branches and is very painful - Obicularis oculi block is used if residual eyelid movement remains after RBB or PBB - Complications - Retrobulbar hemorrhage caused by trauma to orbital vessel - Causes proptosis and conjunctival hemorrhage - Increases pressure on optic nerve, vessels, and globe - Treatment = direct pressure and lateral canthotomy - Globe puncture - Optic nerve sheath trauma - Injected LA tracks back to optic chiasm and will cause contralateral amaurosis and pupil dilatation - Subarachnoid or subdural injection, BE PREPARED TO TREAT RESPIRATORY ARREST - Oscular ischemia - Extraocular palsy and ptosis - Bell's palsy - Intravascular injection - Open globe injury - IOP approaches atmospheric pressure with an open globe injury - Avoid further increases in IOP