Pediatric Airway Anatomy and Physiology PDF

Pediatric Airway Anatomy o Head ▪ Larger in proportion to rest of the body ▪ Larger occiput ▪ In flexed position Absence of muscle tone + weight of head leads to this position...

Pediatric Airway Anatomy o Head ▪ Larger in proportion to rest of the body ▪ Larger occiput ▪ In flexed position Absence of muscle tone + weight of head leads to this position ▪ “We won’t really use a head ring, will more likely use shoulder/neck roll” o Nose ▪ Infant nostrils smaller in relation to trachea size ▪ Infants are obligate nose breathers for 1st year of life o Tongue ▪ Proportionally larger ▪ Smaller oropharynx ▪ Lack of muscle tone in jaw and pharynx will cause tongue to fall back and obstruct airway in a ball- valve fashion ▪ “With adults you typically have to scissor open the mouth; for peds, a gentle pull on the mouth opens everything and tongue follows” o Airway ▪ Larynx Higher in relation to C-spine than adult (C3-4) o “Tends to be a test question” Cords have concave appearance, slant forward and down Airway is more conical in shape Clinical implications o Picture A: adult, cylinder, reached in teenage years o Picture B: infant, funnel/cone, underdeveloped arytenoid cartilage ▪ ETT should be smaller size because airway is narrower as you pass through the cords “Size 3-3.5 are for your babies, anything smaller than that you won’t have a cuff. A microcuff is typically on the end of these so that way you can inflate the balloon past the cords and not mainstem” “Age/4 + 4 = uncuffed, Age/4 +3.5 = cuffed” “Where do we want our cuff leak to be? 20cmH2O” “We don’t want to mask over 20cmH2O to avoid inflating the stomach” ▪ Cricoid cartilage Narrowest portion of the airway ▪ Epiglottis Omega shaped Larger and stiffer than adults o Miller blades recommended to manually lift o “The younger the child, the more likely the epiglottis blocks your view, and you need to directly lift it” Hyoid bone (firmly attached to thyroid cartilage) tends to push base of tongue and epiglottis towards the pharyngeal cavity, causing the epiglottis to lie in a more horizontal position ▪ Vocal Cords Adult vocal cords sit perpendicular to trachea Infant’s vocal cords have lower point of attachment on anterior side of trachea o Vocal cords are slanted downward from posterior to anterior o Downward slope changes angle of entry into the glottic opening and makes ETT insertion more difficult ▪ Trachea/Mainstem Bronchi Infant’s major airways are narrower and shorter Mainstem bronchi divide more equally o Easier to mainstem either side but will more likely be on the right due to decreased angle o As soon as cuff is through the cords, stop  o Precordial should be used to assess placement (usually placed on left) ▪ Tracheobronchial Lumen Same amount of edema can significantly increase airway resistance (adult vs infant comparison) “If you look at their airway versus ours, 1mm of edema can decrease their airway cross sectional area by 75% compared to our 44%” “For them, resistance to airflow is 5-7x greater than adult”  Systems o Respiratory ▪ PVR Increases with o Hypoxia o Hypercarbia o Acidosis o Hyperinflation o Atelectasis o High Hct o Surgical Constriction Decreases with o Oxygen o Hypocarbia o Alkalosis o Normal FRC o Sympathetic stimulation blocking o Low Hct Think about how hypoxia and hypercarbia impact PVR! ▪ Ventilation Considerations In relation to body mass, ventilation is greater reflecting higher metabolic rate Response to hypercapnia o Less in neonate o Even less in preterm neonate o Hypoxemia decreases the response of the neonate to hypercapnia ▪ “Their body has not developed the mechanisms to responds to high CO2 or low O2” Any increase in ventilation is not well sustained o Energy stores can be depleted very easy Neonate is extremely sensitive to changes in arterial oxygen tension Periodic breathing o Seen in preterm infants and some full-term infants o Rapid ventilation with periods of apnea (may last 5-10 seconds) o Uncomfortable to watch, but normal Total Lung Capacity o Approximately 160mL in full term infant o Ventilator → should be pressure support, change set volume to be under this total o “If you change your age right away during setup, the vent should adjust to PS” FRC is half the TLC o Fall in FRC is anticipated with GA o Fall in FRC persists into post-op period ▪ Immature anatomy → Less chest wall stability, weak diaphragm ▪ Maximize ventilation peri-op and post-op ▪ Happens regardless +/- muscle relaxants Closing Volume o Higher in infants and young children than adults o May exceed FRC to encroach on the VT during normal ventilation ▪ Will desaturate quickly because there’s not a lot of reserve despite preoxygenation ▪ Airway closure during normal ventilation may account for lower-than-normal value of PaO2 during infancy and childhood Immature airways tend to collapse easier o “Remember volume is individual, capacity is a few volumes together” o Compliance is the ability of the lungs to expand, elasticity is the ability of the lung to bounce back o These kids have immature airways, and they tend to collapse easier; will need support  o May need physiologic PEEP o Cardiovascular ▪ Cardiac output is dependent on HR secondary to a fixed SV (noncompliant LV) Only way to increase CO is to increase HR Maintaining HR is super important ▪ Code starts when HR is 60 Verbal Airway Evaluation o Presence of URI predisposes patient to ▪ Coughing ▪ Laryngospasm ▪ Bronchospasm ▪ Airway edema ▪ Allergy flare up o Snoring/Noisy breathing can indicate ▪ Tonsil and adenoid hypertrophy ▪ OSA ▪ Pulm HTN o History of stridor/croup ▪ Subglottic stenosis Have smaller ETT sizes available, can be difficult to pass after your through the cords o Recurrent pneumonia/resp infections ▪ Frequent aspiration Secondary to incompetent larynx, GERD (very common in infants), TEF (we’ll talk about next semester), tracheobronchial fistula o Check for previous anesthesia problems ▪ Difficult intubation, mask ventilation, emergence/extubation, MH o Environmental allergies + exposure to secondhand smoke can increase airway reactivity o Congenital abnormalities o Airway ▪ Mallampati criteria ▪ Oral aperture ▪ Loose or missing teeth ▪ Mandibular size and shape Can tell you a lot about intubation ▪ Physically deformed ears (Microtia) Associated with mandibular hyperplasia 4 grades (1 best, 4 worst) o 1: External ear, small ear canal o 2: Partial developed ear, stenotic ear canal o 3: Absence of ear o 4: No canal, nothing Bilateral microtia is associated with 42% of children having difficulty visualizing the larynx (grade 3 – 4 view) Unilateral microtia is associated with less than 5% of children having difficulty viewing the larynx Formation of ears frequently goes with the airway o Ears, mouth, mandible issues suggest potential airway problems Physical Airway Evaluation o Can be difficult because children are frightened ▪ Make it a game  ▪ Get on their level or below their level ▪ May not be comfortable with eye contact ▪ May only get to do visual assessment o +/- respiratory distress ▪ Stridor Can indicate an airway obstruction ▪ Accessory muscle breathing Suprasternal, intercostal, subcostal retractions May need some positive pressure o Obvious congenital/developmental abnormalities ▪ Choana Definition A funnel shaped opening, usually pertaining to the posterior nares One of the communicating passageways between the nasal fossa and the pharynx ▪ Choanal Atresia Congenital disorder where back of the nasal passage (choana) is blocked, usually by abnormal bony or soft tissue (membranous) due to failed recanalization of the nasal fossae during fetal development Occurs in 1:8000 births The presenting symptom is cyanosis at rest relieved by crying or insertion of an oral airway o Remember that infants are obligate nose breathers o These infants may develop airway obstruction during induction (mask ventilation) which is relieved by inserting an oral airway or by intubation Avoid all nasal instrumentation (NGT, nasal airway/suction/ETT) ▪ Cleft Lip/Palate Occur 1:700 births worldwide More common in males Can be caused by genetics or exposure to teratogens Develops in the 1st Trimester Cleft lip o diagnosed by ultrasonography at 18-20wks gestation Cleft palate o diagnosed after delivery Disorders associated with cleft lip/palate o Pierre Robin Syndrome o Downs Syndrome o Klippel-Feil Syndrome o Velocardiofacial Syndrome o Nager Syndrome o Treacher Collins Syndrome o Fetal Alcohol Syndrome o Goldenhar’s Syndrome Anesthesia considerations o Determine extent of defect ▪ Variation of how involved palate is ▪ Usually once you are past tonsillar area, the airway is normal o Determine if other abnormalities are present ▪ Coexisting syndrome ▪ Micrognathia (small jaw) ▪ Glossoptosis (tongue inserts more caudal than normal) o Children with micrognathia, with or without a cleft deformity, are the most difficult to intubate ▪ Specifically, if the child is < 6 months old ▪ Children > 6 months old are easier because the jaw has had time to grow Down Syndrome o Physical Characteristics  ▪ Small mouth ▪ Hypoplastic mandible ▪ Protruding tongue o Children with Down Syndrome frequently need smaller than anticipated ETTs o Atlantoaxial Instability with or without subluxation ▪ Ligaments around C1 and C2 are looser than normal, leading to instability ▪ Sniffing position can cause vertebrae to shift excessively causing compression/damage to spinal cord Avoid extreme head tilting or neck movement Maintain neutral position Review XR or scans if possible VL instead of DL o Potential for difficult intubation Pierre-Robin Syndrome o Physical Characteristics ▪ Pseudo-macroglossia Any condition that causes the tongue to sit in an abnormal position ▪ Hypoplastic mandible ▪ +/- high arched palate ▪ +/- cleft palate o Potential for difficult intubation Treacher-Collins o Physical Characteristics ▪ Mandibular hypoplasia ▪ +/- Cleft Lip or Palate ▪ +/- Choanal Atresia ▪ Macro or microstomia Large or small oral aperture ▪ Macro or Microtia Ear deformities ▪ Associated cardiac disease o Potential for difficult intubation Airway Setup o Gas machine checked o Ambu bag available o Appropriately sized ETTs ▪ 3-5cc syringes o 2 OAWs + 2 tongue depressors o 2 handles with appropriately sized blades o LMA for difficult airway o Suction  Airway/Ventilation o Positioning ▪ Mask ventilation of neonatal infant → maintain normal alignment of head and neck ▪ As infant ages may find that stable extension of the neck (as done with adults) may be beneficial in mask ventilation ▪ Always ensure neutral head and neck position o NPA ▪ Under most circumstances NPAs are avoided to prevent trauma and bleeding from hypertrophied adenoids ▪ Proper length is directly proportional to the distance between the nares and the angle of the mandible o OPA ▪ Tongue is large compared to oropharynx and often obstructs airway ▪ Insertion facilitated by tongue depressor ▪ If inappropriately sized OPA too large may push the epiglottis down, impinge on the uvula (causing swelling) OPA that is too small may aggravate airway obstruction ▪ Take care to avoid trauma to lips, teeth, and tongue ▪ If patient is in stage 2 insertion of an OPA may cause laryngospasm! o Techniques ▪ Mask During mask airway management, all necessary equipment for intubation should be available and ready Ensure mask fits appropriately o Hugs contours of face o Minimizes dead space o Top of the mask: rest on the bridge of the nose o Lower edge of the mask: rest on the mandible Care should be taken to avoid excess pressure on the eyes EC technique Minimize pressure on soft tissues to prevent airway collapse Normally utilized in quick, nonstimulating cases where the patient can SV NOT a protected airway ▪ LMA Primarily designed as substitute for mask anesthesia in SV patients Can be used with CV (as long as pressures are under 20) NOT a protected airway o Not to be used with GERD Can be used for emergency airway management Sizing o Too large and the LMA will not pass the posterior pharynx o Too small and the LMA will pass easily, but will not seal o Not expecting you to memorize chart → Insertion o Cuff inflated or deflated o Lubrication o Sniffing position o Insert with mask aperture facing anteriorly o Index finger in the cleft between the mask and the barrel o Follow palate to guide placement o Advance until some resistance is met o Inflate cuff o If no outward movement is observed with inflation of the mask, the LMA is not properly positioned!  Removal o Controversial o Can be removed awake or deep o Awake ▪ Ensure protective airway reflexes are intact ▪ Stimulating and since not a protected airway may lead to laryngospasm o Deep ▪ Avoids excessive airway irritation and decreases risk of laryngospasm ▪ Airway obstruction possible (may need oral airway) o Make sure you can mask patient! Will help to know you have this as a back up ▪ GETA ETT Sizing o Formula ▪ (Age in years + 4) /4 = uncuffed ▪ (Age in years + 4) /3.5 = cuffed o Be sure to include a size below and above your calculated size to ensure you have correct size ready to go during induction o ETT size refers to internal diameter ETT Depth o In children > 2 years old, the following formulas may be used to calculate the appropriate distance in cm. o Age (years)/2 + 12 or Weight (kg)/5 + 12 o 3 x diameter (“this is what I use”) ▪ Ex: 4.0 ETT should be 12cm @ lip o Check for BBS sounds o Cuff placement o If air in cuff can squeeze cuff and palpate cuff location Cuff vs Uncuffed o Used to use uncuffed ETTs in all kids < 8 o Cuffed ETTs commonly used in all age groups ▪ Consider microcuff ETT for 3.0 and 3.5 ETT sizes when available o Do NOT inflate cuff with intubation ▪ Confirm ETT is in correct location ▪ Listen for a cuff leak and inflate cuff until leak is resolved if indicated o If an air leak is not present, the result may be ischemic damage to the tracheal mucosa o Too large of an air leak may necessitate larger ETT placement (or inflation of cuff if cuffed ETT) o The air leak may be influenced by: ▪ Depth of anesthesia ▪ Presence or absence of muscle relaxation ▪ Head position ▪ Sub-glottic edema Laryngoscopy o Ensure proper positioning ▪ Elevate head with blanket or pillow to ensure alignment of oral, pharyngeal, and tracheal axes ▪ Not necessary in infants and younger children secondary to large occiput ▪ May need shoulder roll in neonate and small infants Sniffing position hurts us rather than helps us o Watch for unstable C-spine conditions ▪ Marfan’s, Trisomy 21 o Teeth ▪ Document pre-op o Miller blade superior for neonates and small infants o MAC blade useful in school-aged children o Technique ▪ Holding the laryngoscope in the left hand insert it into the right corner of the mouth and gently sweep the tongue toward the left side of the mouth ▪ Lift the laryngoscope so that you can view the glottic opening It may be necessary to use your right hand on the anterior portion of the neck to manipulate the thyroid to bring the glottic opening into view or adjust head positioning  Have your assistant hold the trachea where you want it ▪ Insert the Endotracheal tube Nasal Intubation o Insert a lubricated ETT into the infant’s nostril o Advance the ETT until it is in the posterior pharynx o Using a laryngoscope in the same manner as in oral intubation, obtain a view of the glottic opening o Grasp the distal end of the ETT with Magill Forceps ▪ As your assistant advances the ETT, guide its tip into the glottic opening Securing ETT o Do NOT let go of ETT until it is secured! o Check with surgeon when indicated about where to secured ETT ▪ E.g. ENT cases, plastics o Confirm BBS after taping ETT ▪ Small changes in head and ETT position can lead to mainstem intubation in pediatric patients ▪ Hose follows the nose o Disconnect ETT from circuit and hold ETT (even when taped) when repositioning patient (for everything) ▪ This includes diaper changes, bovie pad placement, etc. o Ventilation Management ▪ PCP Preferred method because it is more gentle ▪ Physiologic PEEP PEEP 4-5 (for high closing volumes) ▪ O2 Drop as soon as possible Risk of ROP (retinopathy of prematurity) until 44 weeks o O2 can be fairly toxic to the eyes as baby is maturing ▪ N2O Used in induction/emergence Analgesic properties are helpful for stimulating parts of procedures o Wears off in about 20 minutes Worry about closed spaces (cuff of ETT, cuff of LMA) o Extubation ▪ Prior to extubation, ensure all equipment necessary to ventilate and reintubate are available and ready ▪ Ensure patient is fully awake or deep (no in between with kiddos!) ▪ Full monitors ▪ Awake The patient is allowed to fully emerge from anesthesia and regain their protective airway reflexes Advantages o Ability to protect airway against aspiration of stomach contents, sputum or blood o The patient remains intubated during Stage 2 (the Excitement Stage) protected from the possibility of laryngospasm due to the characteristic hyper-reactive airway during this stage of anesthesia Disadvantage o The endotracheal tube will be irritating causing coughing and retching on emergence ▪ Deep The patient is extubated while deeply anesthetized, then allowed to emerge without an endotracheal tube in place Advantages o Removal of the endotracheal tube before Stage 2, results in a smoother emergence o Decreased coughing or retching puts less strain on incisions and suture lines Disadvantages o Possibility of losing control of the airway o Lack of protective reflexes may make patient more prone to aspiration o Not recommended for airway surgery where bloody drainage will be an issue o Airway Complications ▪ Obstruction Upper airway obstruction interventions o Reposition head  o Chin lift o Oral airway o Nasal airway o Positive pressure (will probably do this before OSA or NPA) o Change anesthetic depth ▪ Laryngospasm Signs and Symptoms o Crowing o Retractions o Difficulty moving air Treatment o Positive pressure o Jaw thrust o Succinylcholine Severe laryngospasm on extubation may be followed by pulmonary edema (if this occurs continue PPV) Remember o This is someone’s baby o Peds airways require meticulous and constant attention o When in doubt, get help o Be prepared for all circumstances o Not a time to be prideful—do what is best and safe for the kid Basic Pediatrics Set-Up o All monitor settings changed to neonate or pediatric o Vent should be set for specific patient o Monitors/Equipment ▪ 3 lead EKG ▪ NIBP ▪ SpO2 ▪ Precordial Stethoscope ▪ Temp probe ▪ Make sure room is warm for neonates and premies Conserve their heat! Bair hugger, humidify/minimize flows, increase room temp (best way), primary way we lose heat is radiation (losing heat to cooler objects in the environment without direct contact) ▪ Bair hugger ▪ Appropriate ambu size and Jackson-Reese circuit o Airway ▪ Suction ▪ LMA Basic Pediatric Setup ▪ 2 blades and handles ▪ Age-appropriate ETTs and stylets One size up and one size down ▪ OAWs ▪ Tongue depressors ▪ Age-appropriate mask ▪ +/- OGT, bair hugger if required for case o IV Kit ▪ 20g, 22g, 24g IV ▪ ETOH pads ▪ Gauze ▪ TQ ▪ Tegaderm ▪ Coband ▪ +/- arm board ▪ EMLA cream (5% lidocaine), Mr. Freeze (spray) for pre-op IV EMLA Cream o Mix of 2.5% Lidocaine and 2.5% prilocaine o Cream placed over site of IV insertion prior to insertion o Onset of numbness can take up to 30min Mr. Freeze o Ethyl Chloride Spray o Numbs area prior to IV placement o May cause ▪ Discolored skin at site ▪ Itching ▪ Frostbite ▪ Slight discomfort/pain o IV Fluids ▪ Most children come back with fluids from pre-op Normally D5 solution Do not bolus dextrose solution—can make hyperglycemic ▪ 500mL LR on volutrol or microdrip tubing ▪ Stop-cock ▪ Extension ▪ T-piece connector ▪ Bubble filter Child who has septal defect, PDA, PFO o Have Available ▪ Vaporizers adequately filled ▪ Propofol Modified Neonatal Setup ▪ Fentanyl (0.5-1mcg/kg) or Morphine (0.1mg/kg) ▪ Muscle relaxants and reversal  ▪ Emergency drugs Atropine 0.02mg/kg Epinephrine 10mcg/kg o Actually, what the fuck I don’t get Kress’s dilution????? HELP Succinylcholine o IV 2mg/kg o IM 4mg/kg ▪ Flushes (consider the age of your child; grab smaller flushes for younger kids) ▪ Find out patients’ weight (or calculate average weight) when looking them out the night before (Age in years x 2) + 10 Pre-Op o Make it fun o Get down to their eye level o Head to toe ▪ Ask specifically about length of pregnancy “Did you carry 9 months” ▪ If premature ask about IVH and assisted ventilation ▪ Family history of anesthesia problems ▪ Sickle cell anemia ▪ GERD Kids up until 9 months can experience GERD ▪ NPO status/guidelines ▪ Recent colds/URI (more reactive airway for 6 weeks) Asthma (inhaler? Last use?) o Medication ▪ Separation anxiety is severe in toddlers Acknowledge their sadness ▪ May need to premedicate with versed Oral Versed Intranasal Precedex Intranasal Fentanyl Oral Ketamine Can make emergence slow or increase emergence delirium ▪ Make separation an adventure Pretend bed is car or train Red wagon if available Princess wave Pre-Induction o If able, transfer to OR table o If anxious, consider how you can tailor induction to keep them happy o Must have for induction ▪ Precordial (but not really) ▪ SpO2 o Can wait until after induction  ▪ EKG ▪ NIBP o Have everything for induction and emergency at an arm’s length Induction o Inhalation ▪ 70% N2O 30% O2 If able, try ‘stun dose’ of N2O prior to Sevo Turn N2O off once out Stage 2 (some places say turn N2O when HR drops) ▪ Gradual or full-blast Sevo Make sure vaporizers are full! ▪ Start at 8, and turn down to 6 eventually Don’t manually ventilate on 8 of Sevo; the benefit of having spontaneous ventilation is that they can regulate their own anesthesia. If they are light, they breathe faster. If they are too deep, they breathe slower. Once you take over, that ability of the child to self-regulate is gone. You can go quickly from MAC to MAC BAR. ▪ IV start per CRNA or ologist or circulator (never give up the airway) o IV ▪ If IV in place may still do combined technique of inhalation and IV ▪ Small gauge has increased discomfort with propofol – consider 0.5mg/kg lidocaine mixed with propofol Maintenance o Volatiles ▪ All volatiles appropriate ▪ Greatest emergence delirium with Sevo ▪ Desflurane is a good choice because it supports HR o Narcotics ▪ Fentanyl is quick on/off, allows titration to patient need ▪ Morphine is a good choice for long procedure with anticipated post-op intubation o Regional ▪ Caudal ▪ TAPS o Non-Narcotics ▪ PR Tylenol “Highly recommend for BMT” ▪ IV Tylenol 10-15mg/kg depending on age ▪ Toradol (max dose 15mg) o Fluids ▪ See fluids lecture, maintenance fluid chart pictured below o “When it comes to kids, short acting is better” o “If patient bucking, flip them off of vent” Emergence o Return of spontaneous ventilation ▪ Make sure fascia is closed ▪ Consider SIMV mode, PS, and your flow trigger ▪ Titrate meds accordingly o Do not stimulate! ▪ Either remove NG/OG or suction when deep, otherwise wait! Will make the patient buck! o Determine if extubation will occur with patient fully awake or deep ▪ Awake Consider using N2O as a bridge Ensure patient is out of stage 2 Suction Pull ETT with positive pressure Immediately apply mask with positive pressure and jaw thrust until adequate respiration is noted ▪ Deep Suction OAW? Pull ETT and immediately provide jaw thrust and positive pressure Ensure patient is ventilating adequately Turn off gas and support airway Potential Complications o Stage 2 (can come back to Stage 2 more than once) ▪ Signs/Symptoms Thrashing Red sclera Dysconjugate gaze ▪ Resolution Return of normal gaze White sclera Gumming of ETT Swallowing Grimace Tear formation o Laryngospasm (can happen with induction especially with instrumentation of the airway) ▪ Definition Forceful, involuntary spasm of the laryngeal musculature from stimulation of the RLN ▪ Causes Upper airway obstruction, secretions, light anesthesia ▪ Treatment FiO2 of 100% Positive pressure (< 20 cm H2O) Jaw thrust Succinylcholine Will most likely have to follow up with positive pressure o Post-Extubation Stridor ▪ Causes High cuff pressures Airway swelling ETT movement in trachea ▪ Signs/Symptoms Stridor and seal like barking cough ▪ Treatment Humidified O2 Steroids Racemic Epi o Bronchospasm ▪ Definition Spasm of the bronchioles Can happen on induction/intubation but also at any time in the case! ▪ Causes Reactive airway disease or recent URI Mainstem ETT (takeoff to the right makes that easier) Mechanical obstruction (kinked ETT) ▪ Signs/Symptoms Difficulty or inability to ventilate even with an ETT in place High peak airway pressure Desaturation May not have ETCO2 or breath sounds with bronchospasm ▪ Treatment FiO2 of 100% Determine underlying problem and correct Medical Treatment o Deepen anesthesia with volatile ▪ Sevoflurane is the most potent bronchodilator that we have o Β-adrenergic agonist via ETT o IV epinephrine/terbutaline or SQ terbutaline o IV/IM ketamine o IV aminophylline, lidocaine, and corticosteroid o Emergence Delirium (warn parents in pre-op about this) ▪ Definition Common post-op problem in peds patients where psychomotor agitation accompanies emergence ▪ Signs/Symptoms Thrashing Crying Yelling ▪ Risk factors All children have potential (great) Pre-op medications Sevo > Iso and Des ▪ Treatment Medications o Precedex (0.5mcg) o Fentanyl (1-2mcg) o Propofol (2.5-3.5mg) Minimize Harm o Saline lock IV o Untangle monitors o Keep calm and stay therapeutic Complicated Pediatric Fluid Management “I want to review some definitions” o Neonate is < 30 days of age o Infant is 1-12 months o Child 1-12 years o Adolescence is after that Pharmacologic Principles o Size ▪ Smaller than adults o Body Mass Distribution ▪ Decreased fat and muscle content (compared to adults); this increases with age o Body Water ▪ % of body weight that is water decreases as you age As the % of body weight that is water decreases, the interstitial fluid space decreases in water content The number of insensible losses is INVERSELY proportional to gestational age (the older the kid, the less water loss) o Losses through respiratory, evaporation, metabolic processes are highest in our smallest kids ▪ Distribution of body water changes with age of child ▪ Total body water – ECF volume = ICF volume ECF = blood, plasma Interstitial is determined by Na and accompanying ions Cells are either going to absorb or excrete water based on the osmolarity of your ECF The inside of your cell is isotonic, its goal is to stay that way Your cell volume will remain constant when isotonic fluids are administered If you give hypotonic solution, it might rapidly increase The predominant extracellular cation is Na The predominant intracellular cation is K Infants are going to be about 40% of their weight that is extracellular fluid o The largest compartment in the ECF is your interstitial fluid o Why am I going over this? It’s important when we think about giving water soluble drugs—they are going to have a larger volume of distribution. Because of that they are going to require a larger, initial dose. Whereas a drug that requires it to go into fat (Fentanyl), those may have a longer clinical effect because these kiddos are more water and not as much fat and muscle—so there’s nowhere for them to redistribute to. o Temperature and Ventilation ▪ Acute hypercarbia is compensated for by loss of HCO3- and Cl ions and water from the cells to the interstitium → shrinks ICF and increased ECF ▪ Hypocarbia and hypothermia shift fluid water, HCO3-, and Cl- into the cells ▪ Another thing you can think about for compensation if things are hitting the fan. If you have a rapid volume loss, avoid hypothermia and maintain hypercarbia and that can help prevent loss of fluid from extracellular to intracellular. Estimating Blood Volume (EBV) o Preterm or LBW: 90-100mL/kg o Newborns: 80-90mL/kg ▪ Degree of variability based on placental transfusion during birth o 3 mo-2 years: ~80mL/kg o > 2 yrs-adolescence: 75-80mL/kg Organ Function o Kidney ▪ 1st year of life, renal plasma flow and GFR are ½ of adult values ▪ Diminished ability to concentrate urine ▪ Preterm infant has increased fractional excretion of Na and elevated serum Cr Usually stabilizes by 2nd month of life Why do you care? The diminished concentrating ability in the urine increases free water loss during excretion of a solute load. The high surface area to volume ratio that is produced increases evaporative water losses during surgery. Because of this increase in free water loss/evaporation loss, infants have large fluid requirements. Dehydration is common for them. Preterm and young infants also have trouble handling fluid and solute loads. Both sodium conservation and regulation of ECF volume are impaired compared to older children and adults.  o Liver ▪ Immature liver function in neonates ▪ Hepatic enzymatic metabolism is reduced ▪ HBF is reduced ▪ Why do we care? That means protein binding is both quantitatively and qualitatively decreased. Not only do we have less, what we have doesn’t work as well. That means when we give a highly protein bound drug, we have a higher free drug concentration. This means that it is important to titrate drugs in neonates—particularly if they have any underlying disease. NPO Rules o Thumbs and pacifiers are okay—but should not dip pacifiers in simply syrup to satiate them. Will increase gastric acid content. o Human milk has faster emptying times that formula and the pH is higher. During the first month of life, breastfed babies tend to gain more weight rapidly than bottle fed. o Advantages of Limited NPO ▪ Decreased hunger and thirst ▪ Increased comfort ▪ Increased patient satisfaction ▪ +/- Decreased incidence of HTN ▪ +/- Decreased need for glucose containing solutions o Implication for Limited NPO ▪ pH and gastric volume no difference noted with clears ▪ Kinetics of gastric emptying Half-life for clear liquids is 10-20 minutes Half-life for solids is 77-277 minutes ▪ Less flexibility with anesthesia start time Preoperative Fluids o Routine use during peds ambulatory surgery is controversial ▪ Pre-op fluids can cause hemodilution, so when you lose blood the amount that is RBCs will be less o Not indicated: ▪ Limited NPO ▪ Expected to eat and drink quickly after procedure o Indicated: ▪ Concurrent illness (Pyloric Stenosis, Sickle Cell Anemia) ▪ Poor nutrition status ▪ Hyperalimentation ▪ Endocrine/metabolic abnormalities ▪ In-patients during fasting ▪ Longer surgical procedures IV Placement o Usually placed after induction o If placed before induction: ▪ Consider EMLA cream, Mr. Freeze, lidocaine infiltration to provide comfort o May require sedation for placement o Size ▪ Consider catheter length and diameter on solution flow rates (Poiseuille’s Law) ▪ Changing the radius has the most effect on flow; when it comes to it, I want you to tell me what is directly proportional and indirectly proportional (know for exam) Indirect = Fluid viscosity, length of tubing Direct = Radius, pressure  Fluids o Isotonic preferred for surgical patients ▪ Most volume losses are isotonic ▪ Isotonic helps with maintenance of serum osmolality, electrolyte stability and preventing fluid shifts o Glucose containing solutions ▪ Operative stress evokes physiologic response that increases blood sugar—hypoglycemia isn’t often seen in healthy patients Another stress response to surgery is an increase in ADH (helps save water and free sodium) ▪ Should not be used to replace fluid deficits, 3rd space losses, or blood losses; rather we use them as a maintenance on a rate limiting device to avoid acute hyperglycemia and hyperosmolality. I just want you to remember that replacing deficits with a glucose containing solution can be problematic. ▪ Glucose levels should be kept above 45mg/100mL to avoid neurologic injury ▪ May be indicated for at risk populations Debilitated infants Small for age Cardiac surgery Refer to pre-op fluid slide to see other at-risk patients o Concurrent illnesses o Poor nutritional states o Hyperalimentation o Endocrine/Metabolic abnormalities o In-patients during fasting o Longer surgical procedures ▪ Symptoms of hypoglycemia Jitteriness Lethargy Temperature instability Convulsions Cool and clammy, need some candy; hot and dry, sugar is high o The Neonate ▪ Susceptible to dehydration and fluid overload ▪ Limited ability to handle Na (related back to the immaturity of their kidneys) ▪ Hyper/hypoglycemia may be an issue Hypo= glucose < 40 Hyper = glucose > 135 (term), >150 (preterm infants) On average, term infants require about 3-5mg/kg/min. Preterm neonates 5-6mg/kg/min of glucose to maintain. Usually, you use a glucose containing solution set up on a pump to do maintenance IVF. Your balanced salt solution for blousing drugs, replacing 3rd spacing etc. o Common Fluids ▪ D5LR ▪ D5¼NS (with or without K) May see in neonates due to their inability to handle Na ▪ NS o Moral of the Story ▪ Children at risk for hypoglycemia → consider glucose containing solutions for maintenance ▪ Use isotonic, glucose-free solutions to treat surgical loss, deficits, and 3rd spacing ▪ Know that losses for kids are a lot of times their minute ventilation and general exposure o Fluid Requirement Calculations ▪ Hourly maintenance fluid rate 4mL/kg/hr for first 10kg 2mL/kg/hr for second 10kg (11-20kg) 1mL/kg/hr for each kg > 20kg thereafter ▪ Trick If >20kg, simply add 40 to their weight for their hourly maintenance Deficit Replacement o Complete replacement of the calculated deficit is frequently unnecessary o Remember to consider factors that may increase fluid requirements above normal ▪ Fever, prematurity, decreased renal concentrating ability  o If replacing, ½ of deficit given in 1st hr, remainder given over next 2 hrs o Don’t stop parenteral nutrition but pay attention to run times! o Must be careful to give only what is truly needed (high risk for fluid overload); get a thorough pre-op/NICU/PICU report. Infants and neonates don’t need much. Could we adjust anesthetic depth, choice of anesthetic, positioning to increase BP before giving lots of fluids? Types of Loss o Blood ▪ Capillary leak and surgical trauma cause extravasation of isotonic, protein-containing fluid into nonfunctional compartments (also known as 3rd space) o Virtual ▪ Anesthetic induced relation of sympathetic tone → vasodilation and relative hypovolemia o The Neonate ▪ Insensible water losses are several times greater because there is transepidermal water loss ▪ Exposed premature infants have 15x more evaporative losses than term during first several days of life ▪ Greater loss via respiration o Replacement of Losses ▪ Blood 1mL of RBC or colloid (5% albumin) for each 1mL of blood lost 3mL of crystalloid solution for each 1mL of blood lost ▪ Third Space Loss Mild: 3-4mL/kg/hr Moderate: 5-7mL/kg/hr Large: may approach 10mL/kg/hr These losses include evaporation and redistribution o Why do we care about redistribution? We care because it can be exacerbated by fluid administration. Premies have low plasma oncotic pressure and protein. Even modest fluid overload can lead to pulmonary edema, prolonged ductal patency and congestive heart failure. It is very much a balancing act. Fluid shifts can be bad, particularly when we are giving hypotonic fluids, because we have a cell membrane that is freely permeable to water. So, the osmolarity of our ECF is approximately equal to that of our ICF. Therefore, plasma osmolality is a good guide for us on what our intracellular osmolality looks like. It shows that changes in ECF osmolality have a great effect on ICF osmolarity. When we have these changes we might see changes with cell function, generalized swelling (anasarca), cell lysis, from their volume being too large. If I have a test question that says mild fluid losses I’m going to give you a number. I will be specific because ranges vary. o This chart is for 10kg child with minimal fluid losses o 3rd spacing → 2-4- 6mL/kg, open belly/bigger cases 8- 10mL/kg o Will be on test Vigilance o To prevent accidental volume overload ▪ Amount of IV fluid available to a child should not exceed the child’s calculated hourly requirement (do not hang a bag that isn’t appropriate for the child if it were to accidently all infuse) ▪ Microdrip ▪ Buritrol (ball-valve closure) ▪ Dial-a-flow o Other concerns ▪ Warm fluids ▪ Blood set-up ▪ Bubble filter Assessing IV Volume o Begins with knowledge of age-related norms (ask yourself these questions) ▪ Is HR persistently high or does it vary with surgical stimulation? ▪ Is the pulse pressure narrow? Could indicate ↓LV SV or ↓preload ▪ Is the BP low for age? Does it vary with PPV? Can help determine if needing IVF, +/- anesthesia ▪ Are the extremities warm? ▪ How is capillary refill? ▪ UO? Should be 0.5-1mL/kg/hr ▪ Fluid challenge/Test: Bolus 10 - 20 mL/kg ▪ Don’t react to one piece of data, look at the overall patterns Common Pediatric Procedures Rules of Pediatric Surgery o Preparation ▪ Prepared for all scenarios ▪ Emergency equipment within reach o Open and closed loop communication ▪ Talk to surgeon before you do anything ▪ Be clear/concise ▪ Question or concerns? Voice them! o Teamwork ▪ Do not discount any staff in the room ▪ Everyone is there to provide help o Back-up ▪ Do not hesitate to ask for help or second opinion BMT (Bilateral Myringotomy with Tubes) o Patient Population ▪ Usually, health kids with exception of cold or ear infections ▪ Done to treat recurrent otitis media o Procedure ▪ Insertion of ventilation tubes into tympanic membrane with opening so fluid can drain o Position ▪ Supine, arms at sides ▪ Will turn head side to side o Anesthetic Plan ▪ Mask case ▪ Inhalation induction with 70/30 N2O/O2 with Sevo Once on second ear, turn gas off ▪ No IV or meds ▪ Rectal Tylenol T&A (Tonsillectomy and Adenoidectomy) o Patient population ▪ Usually healthy kid ▪ Performed for treatment of hypertrophic tonsils/adenoids and recurrent respiratory infections o Procedure ▪ Excision of palatine tonsils and adenoids o Position ▪ Supine, arms at sides ▪ Bed will be turned 90 degrees o Anesthetic Plan ▪ Pre-op Versed Atropine given as antisialagogue and prevent bradycardia ▪ Induction Inhalation vs IV GETA o Ask surgeon for preference on securement location o ETT either taped to bottom of lip or marked with tape ▪ Maintenance Low O2 o Cautery is used o Mouth is held open via device (very stimulating) IVF o Can’t eat or drink afterwards; give something with dextrose o Can help with N/V Antiemetics o Decadron for swelling (ask first) o Zofran OAW prior to extubation per surgeon  Empty stomach (OGT dropped to empty stomach before end of case) ▪ Extubation Deep or awake are acceptable Wear glasses Transport laterally with blow by oxygen with HOB elevated o Complications ▪ Bleeding (most significant) 75% rebleed in 6 hours post-op, 25% rebleed in 24hrs Can be seen as scar slough off Can swallow large volume of blood o If inducing rebleed patient, they are considered a full stomach Will need IV access and hydration established prior to induction if coming to OR for intervention Inguinal Hernia Repair o May be unilateral, unilateral with diagnostic look on other side, or bilateral o Patient Population ▪ Variable o Position ▪ Supine, arms at sides o Anesthetic Implications ▪ Pre-op +/- premedication ▪ Induction Inhalation vs IV Caudal block ▪ Maintenance Narcotics Non-narcotic pain medications IVF (10-20mL/kg) o Usually able to drink afterwards o Decreases PONV so can be helpful ▪ Emergence/Extubation Minimize bucking (more bucking = more likely to damage repair) Deep vs awake Umbilical Hernia Repair o Patient population ▪ Usually > 1yr, often > 3 yr Usually resolve on own with time ▪ Often healthy o Procedure ▪ Repair of hernia in the belly button o Anesthetic Implications ▪ Induction Inhalation vs IV TAPS block (helps minimize pain but may take a while to take effect since surgery is so fast) ▪ Maintenance IVF (10-20mL/kg) Narcotics Non-narcotics Zofran ▪ Emergence/Extubation Minimize bucking (more bucking = more likely to damage repair) Deep vs awake  Pyloromyotomy o Hypertrophy of muscle fibers of the pyloric sphincter resulting in gastric outlet obstruction o Olive shaped mass palpable in abdomen o Is NOT a surgical emergency. It is a medical emergency. Need to correct fluid and electrolyte imbalance (d/t persistent vomiting) o Patient Population ▪ Boys > Girls ▪ Usually only several weeks old ▪ Healthy except for projectile vomiting from gastric outlet obstruction o Positioning ▪ Supine ▪ Patient may be turned 90 on bed o Anesthetic Implications ▪ Empty stomach with OGT while patient awake; want them to vomit ▪ RSI ▪ Patient needs to be fully awake for extubation o Complications ▪ Delayed emergence “These kids have dehydrated hyperchloremic metabolic alkalosis. They will start to have an abnormal response to CO2. Central chemoreceptors on the ventrolateral surface of the medulla detect pH. The change in pH causes them to reset making it take forever to wake up because they do not response to CO2 the same.” ▪ Postoperative respiratory depression ▪ Both are the result of pre-operative alkalosis on the pH of CSF Broviac and Mediport o Patient Population ▪ Patients requiring frequent or long-term IV access o Procedure ▪ Done under fluoroscopy ▪ Broviac or Hickman Like CVL ▪ Mediport Small port placed under skin with connection to central circulation o Anesthetic Implications ▪ Induction Inhalation vs IV ▪ Maintenance Not very painful (1/2 dose narcotics usually sufficient) May see ectopy while surgeon threading catheter ▪ Emergence Awake vs deep  o Special Considerations ▪ Sickle cell Warm them (cold precipitates sickling; sickling causes vascular occlusion and is incredibly painfully) o Warm room o Bair hugger o Fluid warmer IVF Preinduction EKG Core temp monitors Detailed history o Acute chest syndrome o Last blood transfusion o Pain, dehydration and cold can cause sickling; Avoid hypercarbia ▪ Cancer Family interaction Immunocompromised o Scrub the hub!!!!! Chemo o Dehydrated o Pain o How advanced is their cancer? May have adjunct procedures o Bone marrow biopsy o LP Circumcision o Neonatal ▪ Done within day or two after delivery ▪ Simplest anesthetic technique is subcutaneous ring block at base of penis Potential adverse effects are hematoma and ischemia of penis o Other ▪ May be done later in life Evidence showing uncircumcised males have higher incidence of UTIs which could lead to parenchymal damage Conflicting recommendations ▪ GA indicated ▪ Consider penile ring block for post-op analgesia Nissen Fundoplication o Used to treat GERD o Fundus of stomach is wrapped around 3-4cm segment of the lower esophagus to provide reinforcement o May include G-tube o Patient Population ▪ Varied o Procedure ▪ Laparoscopic vs open (usually lap) o Anesthetic Implications ▪ Patients have chronic GERD RSI ▪ Bougie placement should be done with extreme caution (document “done per surgeon request”) Passed from mouth to esophagus so surgeon knows how big the esophagus should be and how much to wrap  Strabismus o Deviation of one eye relative to the visual axis of the other ▪ Esphoria (inward) ▪ Exophoria (outward) ▪ Esotropia/convergent (inward deviation of both eyes) o Surgery ▪ Repositioning of extraocular muscles ▪ High incidence of PONV IVF Zofran ▪ Oculocardiac reflex (5 and Dime) Trigeminovagal reflex Due to mechanical stimulation of the eyeballs Presents as sinus bradycardia → can lead to arrest ▪ Treatment Tell surgeon to FKN STOP Administer meds (atropine, glyco)