Peds 1&2 Flashcards
Neonate
Birth to 30 days
Post-gestational age (PGA) calculation
Post-gestational age (PGA) =
(# wks gestation @ birth) + (current age in wks)
Pre-term
< 37 weeks
What is considered low birth weight?
< 2500 grams
Extremely low gestational age (ELGAN):
- 23-27 weeks gestation
- all organs immature
- most vulnerable peds pt
Most vulnerable peds pt
Extremely low gestational age (ELGAN):
ALL pre-terms have potential for:
- Respiratory distress
- Apnea
- Hypoglycemia
- Electrolyte disturbances (▼Mg++, Ca++)
- Infection
- Hyperbilirubinemia
- Polycythemia
- Thrombocytopenia
Former premature infants up to ____ PGA are at increased r/f _____ and _____, requiring post-op monitoring & admission.
Former premature infants up to 60 weeks PGA are at ↑ r/f postop apnea and bradycardia, requiring postop monitoring & admission
Primary changes that occur at birth:
- Placenta is no longer primary source for oxygenated blood
- Ductus venosus closes
- Ductus arteriosus closes (d/t increased PaO2)
- Foramen ovale closes (functional closure—could reopen bc not anatomically closed yet)
- PVR ↓
- SVR ↑
Changes at Birth: Transitional circulation
- Occurs at birth for 1st several weeks
- Hypoxia, hypercapnia, or hypothermia can lead to…
- ↑ PA pressure
- reversal of flow through foramen ovale
- re-opening of ductus arteriosus
- shunting
- This hypoxia is difficult to correct
Fetal Circulation = ____PVR and ____SVR
High PVR
Low SVR
Cardiovascular System: Newborn heart
- Structurally immature
- Fewer myofibrils
- Sarcoplasmic reticulum immature
- Cardiac Ca++ stores reduced
-
greater dependency on serum ionized Ca++
- particularly vulnerable to effects of citrated blood products
-
greater dependency on serum ionized Ca++
Minimal intrauterine pulmonary blood flow =
only ~ 10% of the cardiac output
Newborn heart ventricles are _______(more/less) compliant.
less
What is cardiac output dependent upon in the neonate?
CO is HR-dependent
Baroreceptor reflex immature in neonate, so…
inability to substantially compensate for
hypotension w/ reflex tachycardia
Neonatal heart has ______ dominance and the ____ is immature.
Neonatal heart has PSNS dominance; SNS is immature. Therefore, there is tendency of bradycardia w/ suctioning & DL
Resting CO in neonate at birth
~400 mL/kg/min
Resting CO in infant
200 mL/kg/min
Resting CO in adolescent
100 mL/kg/min
The neonatal myocardium is not as compliant compared to an older child. What does this mean?
- Increased preload does not increase SV to same degree
- Hypovolemia and bradycardia produce dramatic ↓in CO that threaten organ perfusion
What is the preferred treatment of bradycardia and ↓ CO in peds pts and why?
Epinephrine (rather than atropine)
increases contractility & HR
What is the leading cause of bradycardia in children?
Hypoxia
Minimum SBP (without anesthesia) for neonate
70
Minimum SBP (without anesthesia) 2-10 yrs old
Minimum SBP (without anesthesia) 2-10 yrs old =
70 + age (in yrs) X 2
ex: 5 yr old = 70 + (5x2) = 80 SBP
Minimum SBP (without anesthesia) > 10 years old
90
Neonate Pulmonary System
- Alveoli ↑ in number & size up until 8 yo
-
Infants: small airway diameter = ↑ resistance
- Highly compliant airway & chest wall (more collapsible lungs; see retractions and flaring in distress)
- Early fatigue of diaphragmatic & intercostal muscles until age 2 (type 1 muscle fibers (slow twitch fibers that are resistant to fatigue) not mature)
- O2 consumption is 2-3 x’s the adult w/ increased alveolar ventilation
- Angulation of R mainstem bronchus (more susceptible to R mainstem intubation)
Neonate vs Adult
Oxygen consumption
Neonate: 6 mL/kg/min
Adult: 3.5 mL/kg/min
Neonate vs Adult
Alveolar Ventilation
Neonate: 130 mL/kg/min
Adult: 60 mL/kg/min
Neonate vs Adult
Respiratory Rate
Neonate: 35 bpm
Adult: 15 bpm
Neonate vs Adult
Tidal Volume
Neonate: 6 mL/kg
Adult: 6 mL/kg
Infant Airway
- Larger tongue in smaller submental space (less space to get a view)
- Edentulous
- Obligate nasal breathers
- Higher larynx (C2 to C4) (more anterior view)
- Funnel shaped larynx with narrowest region @ cricoid ring
- Omega shaped epiglottis = narrower; more difficult to lift
- Angled vocal cords (slant caudally) (more anterior view)
- Large occiputs & “sniffing” position favored for axis alignment
- Short trachea (4-5 cm) (head manipulation can lead to inadvertent R mainstem or extubation)
Gas Flow
- Young children have elevated airway resistance at baseline
- Diameter of small airways does not significantly increase until approx 5 yo
- Turbulent airflow is present to 5th bronchial division
- 50% ↓ in radius = ↑ pressure 32X
- Very prone to respiratory distress w/ any upper airway irritation or swelling
- Resistance inversely proportional to radius4 for laminar flow and radius5 for turbulent flow.
O2 consumption & CBF in brain of children compared to adults
O2 consumption & CBF in brain of children is
~50% greater
than adults
Myelinization & synaptic connections not complete until what age?
Myelinization & synaptic connections not complete until
age 3-4 yrs
Rapid growth of brain in first…
…2 yrs of life
When do the fontanels close?
Anterior fontanel closed by 18 months
Posterior fontanel closed by ~2 months
Which type of muscle fibers are not mature in the infant?
- type 1 muscle fibers not mature
- (slow twitch fibers that are resistant to fatigue)
Anesthesia-Induced Developmental Neurotoxicity:
our knowledge is still growing in this area
- Increased and accelerated neuroapoptosis w/ virtually all anesthetics
- Single exposures of short duration are usually of no consequence
- Repeated &/or prolonged exposures at a young age (< 3-4 yrs) may be associated w/ later behavioral & learning difficulties- we do not have conclusive evidence
Pain: Somatic pain
-
Somatic pain: conveyed by unmyelinated C fibers (slow)
- Leads to protective reflexes such as autonomic reactions, muscle contraction, and rigidity
- C fibers fully functional from early fetal life onward
- Connections b/t C fibers and dorsal horn neurons not mature before 2nd wk life but nociceptive stimulations transmitted to dorsal horn by C fibers elicit long-lasting responses
What kind of response do neonates have to nociceptive stimuli and why?
- Neonates have exaggerated response to nociceptive stimuli
- Inhibitory control pathways immature at birth & develop over first 2 wks
Pain: Painful Procedures
- Painful procedures during neonatal period modify subsequent pain responses in infancy and childhood
- Pre-emptive analgesia leads to reduction in magnitude of long-term changes in pain behaviors
- Use pain scale appropriate to developmental level of child (< 3 yo usually unable to self-report)
- Procedural pain in infants and young children: common use of FLACC scale
Neuraxial Considerations
-
Conus medullaris ends at ~ L1 in adults and L2–L3 in neonates & infants.
- Conus medullaris is at L3 at birth & migrates to L1-L2 by 3 yrs
- In infants, line across iliac crests (intercristal line) crosses vert. column at L4–L5 or L5–S1 interspace, well below termination of spinal cord
- Dural sac in neonates and infants terminates in more caudad location compared to adults = S3 compared to adult S1
- Infants: lack lumbar lordosis compared to older children predisposes infant to high spinal blockade w/ changes in positioning
Renal
-
GFR impaired at birth but improves throughout 1st yr
- Greatest impairment first 4 wks of life
- Renal maturation delayed further w/ prematurity
- Renal tubular concentrating abilities do not achieve full capacity until ~2 yrs
- Very premature infants easily become hyponatremic bc of reduced proximal tubular reabsorption of Na+ & H2O and reduced receptors for hormones that influence tubular Na+ transport. As many as 1/3 of ELBW neonates develop hyponatremia.
-
Half-life of meds excreted by glomerular filtration are prolonged in very young
- In contrast, during childhood, renal clearance rate may increase to levels higher than adult clearance rates!!!!
Liver: Enzyme systems
- Enzyme systems still developing up until 1 yr of age
- Phase I CYP450 system is 50% of adult values at birth
-
Phase II (conjugation reactions) are impaired in neonates
- Long E½t of benzos and morphine
- Decreased bilirubin breakdown d/t reduction in glucuronyl tranferase (leading to jaundice)
- glucuronyl transferase also needed for metabolism of Tylenol
Liver: glycogen stores
Minimal glycogen stores = prone to hypoglycemia
Liver: Proteins
- Lower levels of albumin/other proteins for drug binding in newborns = larger proportion of unbound drug circulating
Liver: Clotting Factors
- Hepatic synthesis of clotting factors reach adult levels w/in 1 wk of birth
- At birth, vitamin K–dependent factors (2, 7, 9, 10) are 20-60% of adult values
- In preterm infants, values even less
- At birth, vitamin K–dependent factors (2, 7, 9, 10) are 20-60% of adult values
GI
- Coordination of swallowing w/ respiration not mature until 4-5 months old = high incidence reflux, especially in pre-terms
- Gastric juices less acidic (more neutral) up to ~3 yrs old
- Generally slower absorption of oral meds compared to adults
- GI tract is generally slower in children than adults
Specific GI differences between adults and children
- Children have differences in:
- gastric pH
- emptying time
- intestinal transit
- immaturity of secretions
- activity of both bile and pancreatic fluids
- Adults have a larger GI tract, faster gastric emptying time, and more protein transporters, which all cause an increase in absorption compared to children.
Thermoregulation
- Large surface area to body weight
- Lack of subq tissue as an insulator
- Inability to shiver: metabolize brown fat to ↑ heat production → can lead to met acid & ↑ O2 consumption
Factors of Thermoregulation
- Factors: cold OR, anesthetic-induced vasodilation, room-temp IV fluids, evaporative heat loss from surgical site, cool irrigating solutions on field, cool/dry anesthetic gases
- Active warming is critical:
- Warm OR; use warming mattress; incubators; cover w/ blankets; head coverings (up to 60% of heat loss); transport in isolette; humidify gases; use plastic wrap on the skin; warm prep & irrigation solutions; change wet diapers & remove wet clothing
- Anesthetics alter non-shivering thermogenesis in neonates
What is the most effective strategy to minimize heat loss in surgery in children >1 hr?
Forced air warmers:
most effective strategy to minimize heat loss
in surgery in children > 1 hr
Temp Monitoring
- Essential for all peds cases
-
Hypothermia:
- delayed emergence
- reduced degradation of drugs
- increased infection
- Hyperthermia: MH?
What is the best temp monitoring in children?
Core temp best measure:
mid-esophageal probe
Advantage to axillary temp monitoring
Advantage to axillary temp if properly positioned:
proximity to deltopectoral group
improves recognition of elevated temp in MH
Forehead temp monitoring
Forehead temp:
not advised; 10 MH episodes occurred that were unrecognized w/ forehead temp (Barash)
Body Composition: TBW
TBW is highest in premature infants
&
decreases w/ age
Half life of meds compared to children and adults
Half-life of meds in >2 yrs old is
shorter or equivalent to adults
d/t significant CO to liver & kidneys
Protein binding and drugs in neonates
- Protein binding: < 6 months have decreased albumin & alpha-1 acid glycoprotein (AAG)
- Higher free-fraction of protein bound drugs
- Free fraction of lidocaine will be higher in very young
Neonates have less fat & muscle. What effect does this have on meds?
Drugs that depend on redistribution to fat for termination of action will have prolonged effects
Body Composition: Water soluble drugs
- Water soluble drugs have larger Vd
- Need larger initial dose (Sch; abx)
- Larger Vd can delay excretion
Hematocrit & Blood Volume
- Lower P50 of fetal hgb: L shift (19 mmHg vs. adult normal of 26 mmHg)
- Target hct in neonates higher d/t L shift & decreased CV reserve (minimum hct 40% instead of 30%)
- Neonatal polycythemia (central hct > 65%) occurs in 3-5% of full-term neonates
- Neonates have increased r/f bacterial infection d/t immaturity of leukocyte function
- Physiologic anemia 2-3 months old
____ of transfused PRBC’s increase _____ about ______
4-5 mL/kg of transfused PRBC’s increase hgb ~ 1 g/dL
Max Allowable Blood Loss (MABL)
-
Max allowable blood loss calculation
-
Variables:
- EBV
- patient starting hct
- minimum allowable hct
- MABL = EBV X [(starting hct - target hct)/ starting hct]
-
Variables:
Components of Fluid Replacement
- Fasting (NPO) deficit: (maintenance rate x hrs NPO for deficit)
- Baseline maintenance fluid requirement: LR most cases
- Replacement of blood loss: 3:1 crystalloid replacement
- Evaporative loss: based on invasiveness of surgery
Fluid Replacement
Holliday-Segar formula
- 4:2:1:
- < 10 kg: 4 mL/kg
- 11-20kg: 40 mL + next 10 kg @ 2 mL/kg
- > 20 kg: 60 mL + anything over 20 kg @ 1 mL/kg
HOLLIDAY-SEGAR: New Trends
- Rather than 4-2-1, new guidelines recognize impact of ADH secretion on fluid status
-
Healthy children undergoing elective surgery
-
Administer 20-40 mL/kg of crystalloid (balanced salt solution) over duration of case
- Takes into account maintenance fluid & NPO deficit
- and then still replace blood loss at 3:1
- Takes into account maintenance fluid & NPO deficit
-
Administer 20-40 mL/kg of crystalloid (balanced salt solution) over duration of case
- Be familiar w/ both
Fluid Replacement
-
LR typically used for maintenance in healthy children
- Glucose containing IVF may be needed in infants < 6 mo’s & in others at r/f hypoglycemia
- Minimize potential for error: smaller IV bags; buretrols
- Eliminate all air from IV line
Fluid Replacement: TPN
-
Do NOT stop TPN suddenly; either continue in OR or ramp down & bridged w/ glucose-containing IVF (ok to stop lipids)- deduct this from hourly maintenance calculated rate
- Never abruptly d/c TPN- circulating insulin levels have acclimated to this basal infusion of glucose and hypoglycemia will be problematic. Some do cut back to 1/3 to 1/2 d/t increase in glucose release d/t surgical stress- if you choose to do this then be sure to monitor glucose
Recognizing dehydraton in infants
- Recognize dehydration in infants: best measure of deficit is weight
- Mild: ~ 50 mL/kg deficit– dry mouth, poor skin turgor
- Moderate: ~ 100 mL/kg– mild sx + deficit sunken fontanel, oliguria, tachycardia
- Severe: ~ 150 mL/kg– moderate sx + sunken eyes, hypotension, & anuria
Intraoperative Fluid Management
-
Requires knowledge of age-related norms for HR and BP
- HR persistently increased, or vary w/ surgical stim?
-
Pulse pressure narrow, or, more ominously, is BP reduced for age?
- Does it vary w/ positive-pressure breaths?
- Warm extremities?
- Cap refill brisk?
- What is UOP?
- Are these variables changing?
- What is the rate of the change?
- When hypovolemia is suspected, observing response to a 10-to20-mL/kg bolus of isotonic crystalloid or colloid may test the hypothesis.
Postop Fluid Management
- Isotonic crystalloid (LR) at ½ rate described in original 4-2-1 fluid regimen (ex: 2:1:0.5)
- If NO oral intake after 6-12 hrs, initiate standard maintenance fluid therapy (4-2-1) w/ hypotonic saline (0.45% saline) +/- glucose to avoid hypernatremia and fluid overload from prolonged administration of isotonic solutions.
Glucose/Hypoglycemia
- Routine use of glucose-containing IVF periop in children is not recommended
- Exception: Children at high r/f hypoglycemia– can use D5½NS @ maintenance rates
- Continuous TPN: must not suddenly stop
- Children w/ mitochondrial dz will definitely need glucose containing replacement fluid
“In general, most meds will have ___ E½t in preterm and term infants, a ____ E½t in children > 2 years up to early teenage years, and a _____ of E½t in those approaching adulthood.”
“In general, most meds will have
prolonged E½t in preterm and term infants,
a shortened E½t in children > 2 yrs up to early teenage yrs,
and a lengthening of E½t in those approaching adulthood.”
Inhaled Anesthetics:
Uptake is more rapid in children for several reasons…
- ↑ RR & CI
- larger proportion of blood to VRG (heart, brain, GI, kidneys, endocrine)
-
↓ tissue and blood solubility in infants
- Alveolar vent to FRC ratio is 5:1 in infants vs 1.5 :1 in adults
- ↑ r/f anesthetic overdose in infants/ toddlers
- ↑ incidence of hypotension in neonates & infants upon inhalational induction.
- More rapid uptake can unmask negative inotropic effects of volatiles in infant
MAC of VA’s
- MAC of VA’s (other than Sevo) ↑ until 2–3 months old and steadily declines w/ age thereafter
-
Sevo: Exception = MAC remains constant in neonates & infants up to 6 months
- MAC up to 6 months is ~3.2%
- MAC 6 mo – 12 yrs is constant at 2.4%
-
Sevo: Exception = MAC remains constant in neonates & infants up to 6 months
What is the primary agent used for inhalational induction?
-
Sevoflurane is primary agent used for inhalational induction
- Halothane also has low pungency but no longer used in US
- halothane frequently caused bradycardia at induction
- Halothane also has low pungency but no longer used in US
- Use of desflurane for induction limited by pungency
Table 7.4. Determinants of the Rapid Wash-in of Inhalational Agents in Infants Compared With Adults
- Greater ratio of alveolar ventilation to FRC
- Greater fraction of CO distributed to the VRG
- Reduced tissue/blood solubility
- Reduced blood/gas solubility
Inhaled Anesthetic Effects:
Respiratory
- Respiratory: same as adults:
- overall ↓MV
- ↓TV w/ ↑RR
- Depressed response to CO2 & hypoxia
- As concentration ↑, apnea ensues
- overall ↓MV
Inhaled Anesthetic Effects:
CV
- Dose dependent depression
- Halothane has greatest depression of contractility
- Sevo usually maintains or increases HR during induction
- All can cause prolonged QT
Inhaled Anesthetic Effects:
Liver
Halothane hepatitis:
antibody reaction; repeated exposure
Induction Agents (overall)
- Neonates: Immature BBB & decreased metabolism can increase sensitivity
- Older children & adolescents generally require increased doses of induction agents compared to adults
Induction Agents:
Propofol
-
Propofol
- Most commonly used IV induction agent in children
-
Pain of injection can be reduced with a mini Bier block:
- 0.5-1 mg/kg of Lidocaine for 60 sec
- Antiemetic properties
- Propofol infusion syndrome: long term infusions in ICU avoided in infants & children; still appropriate for TIVA
- Egg/soy: only avoid if documented anaphylaxis w/ eggs
Induction Agents:
Ketamine
- Ketamine: can be used IM, IN, PO, IV
- Induction w/ ketamine preferred in cyanotic heart dz, septic shock, & induction for mediastinal mass (need spontaneous ventilation)
- Emergence irritation can be reduced w/ co-admini w/ midazolam & waking up in a dark, quiet room
Induction Agents:
Etomidate
Etomidate:
only approved for use in age >10 yo in US;
0.2-0.3 mg/kg IV
Induction Agents:
Thiopental
Thiopental:
no longer available in US;
3-5 mg/kg IV
Sedatives:
Midazolam
- Midazolam: most widely used anxiolytic pre-op
- Oral dosing: dose increases in younger pts; poor oral bioavailability; bitter taste; allow 10-15 min
- Reversal: flumazenil 0.01 mg/kg IV
- Hepatic metabolism (CYP 3A4) & renal excretion
Sedatives:
Ketamine
- Ketamine
- Severe cognitive/ behaviorally challenged older children may have to be given IM Ketamine for sedation in preop (2-5 mg/kg)
- Onset will be 3-5 min w/ 30-40 min DOA
Sedatives:
Dexmedetomidine
-
Dexmedetomidine
- Hypotension w/ loading doses; bradycardia w/ high dose infusion
- Not adequate as sole anesthetic but can be helpful as adjunct
- Useful in awake FOB, radiological procedures, & reduction of emergence delirium
Opioids (in general)
- Variety of choices: onset, potency, duration, & metabolism are factors just like in adults
- Also consider previous exposure to opioids (tolerance), severity of pain, & other multi-modal strategies
Opioids:
Fentanyl
- Most widely used opioid intra-op in children
- Dosing typically in range of 1-3 mcg/kg (IV) per single dose & titrated for effect
Opioids:
Remifentanil
Excellent for neonates d/t immaturity of renal/ hepatic metabolism/excretion
Opioids:
Demerol
Primarily given for shivering in small doses
Opioids:
Codeine
- Historically very commonly prescribed postop
- Withdrawn from markets d/t respiratory events
- SNP’s in ultra-rapid metabolizers confer r/f OD
Non-opioids:
Acetaminophen
- 10-15 mg/kg PO
- 15 mg/kg IV q6hrs (10-15 min onset)
- Rectal absorption is slow (1-2 hrs)
Non-opioids:
Ketorolac
- Typical dose IV 0.5 mg/kg
- Ask surgeon before giving
- Caution w/ all NSAIDS in severe asthma
Muscle Relaxants
- NMJ not fully mature until ~2 months of age
-
Infants: may be more sensitive to NDNMB but also have larger VD so dose/kg is usually same as adults
- Exception: Rocuronium- dose is lower in infants
- Always use nerve stimulator, response highly variable
-
Infants: may be more sensitive to NDNMB but also have larger VD so dose/kg is usually same as adults
- May see prolonged duration of action d/t immature renal/hepatic elimination
- Routine reversal for TOFR <0.9
- Infants & children, neostigmine dose is 30-40% lower than adults (0.02-0.04 mcg/kg) co-administered w/ anticholinergic
Succinylcholine
- Higher Sch doses needed in in neonates & infants d/t larger VD (3mg/kg)
- Sch IM 4mg/kg paralyzes w/in 1-2 min
- duration may be up to 20 min
-
Sch is limited to RSI and emergency tx of laryngospasm in Peds
- When given, concurrent atropine (0.02 mg/kg) administration is routine practice to prevent bradycardia and asystole (even with single dose administration)
- R/f bradycardia; hyperkalemia; masseter spasm; MH in children w/ undiagnosed myopathies
- Atracurium/ Cisatracurium: particularly useful in newborns and children w/ immature or abnormal hepatic or renal function (Hofman elimination…pH/temp dependent)
Local Anesthetics
- CO and local blood flow are 2-3X greater in infants than adults so systemic LA absorption is ↑
- Epinephrine is effective in slowing systemic uptake
- Plasma concentration of AAG is very low at birth (0.2 to 0.3 g/L) and does not reach adult levels (0.7 to 1.0 g/L) before 1 yo
- Free fraction of all LA’s is ↑ in infants
- Max doses of all amino-amides must be reduced
-
LA’s are metabolized by CYP450.
- CYP3A4 metabolizes lidocaine and bupivacaine.
- CYP1A2 metabolizes ropivaciane.
- These hepatic microsomal enzymatic systems are immature at birth and, as a result, hepatic clearance of amide anesthetics is delayed in children.
- Levels of plasma esterases that metabolize ester LA’s are also lower in infants; however, delay in metabolism is not significant.
Local Anesthetics
Max Doses (bolus and infusion)
Lidocaine
Lidocaine
Bolus Dose = 4 mg/kg
Infusion = 0.8 mg/kg/hr
Local Anesthetics
Max Doses (bolus)
Lidocaine with Epinephrine
Lidocaine with Epinephrine
Bolus dose: 7 mg/kg
Local Anesthetics
Max Doses (bolus and infusion)
Ropivacaine
Ropivicaine
Bolus: 3 or 2.5 mg/kg
Infusion: 0.3 mg/kg/hr
Local Anesthetics
Max Doses (bolus and infusion)
Bupivacaine
Bupivacaine
Bolus: 2.5 mg/kg
Infusion: 0.2 mg/kg/hr
Local Anesthetics
Max Doses (bolus and infusion)
Chloroprocaine
Chloroprocaine
Bolus: 12 mg/kg
Infusion: 12 mg/kg/hr
RR Range:
Preterm neonate
40-70
RR Range:
0-12 months
24-55
RR Range:
1-5 years
20-30
RR Range:
5-9 years
18-25
RR Range:
9-12 years
16-22
RR Range:
12 years and older
12-20
Developmental Considerations
- Preschool age: distraction & premedication
- Offer flavoring for the O2 mask if available
- Pre-op prep w/ OR equipment (see the mask, pick a flavor, etc.); child life specialists can assist
- Distractions: music/ singing, story telling, jokes, guided imagery; “changing flavor” of mask
- Avoid bright lights, loud voices, & lots of extra personnel in room
- Consider parental presence (especially in ages 1-6); parents must be educated on what to expect at induction
Preoperative Evaluation
- Standard adult history and physical exam must be adapted; some topics that require further emphasis in children
- Birth history; prematurity
- Neuro development: appropriate for chronological age? psychological issues?
- Airway anomalies, surgical history, previous intubations, and general medical health (heart, lung, endocrine, renal disorders)
- Genetic or dysmorphic syndrome?
- Potential for anomalies in the cervical spine (eg, Down syndrome) or craniofacial dysmorphia
-
Family history:
- MH
- pseudocholinesterase deficiency
- PONV
- congenital myopathies
- bleeding
- No lab work indicated for healthy children undergoing procedure w/ minimal blood loss anticipated
- Routine pregnancy testing controversial; parents may decline; history alone can be unreliable
- Higher r/f latex allergy in certain peds populations: spina bifida, myelodysplasia, urinary tract malformations; multiple previous surgeries
Airway History
- Presence of URI
- Snoring or noisy breathing
- Presence and nature of cough
- Past episodes of croup
- Inspiratory stridor, usually high pitched
- Hoarse voice
- Asthma and bronchodilator therapy
- Repeated pneumonias
- Previous anesthetic problems, particularly related to the airway
- Atopy, allergy
- History of a congenital syndrome
- Parents smoke in the house?
- Suspicion of a C-spine anomaly?
Airway History
Presence of URI could indicate what?
- Presence of URI = predisposition to
- Coughing
- Laryngospasm
- Bronchospasm
- Desat during anesthesia
- Postintubation subglottic edema
- Postop desat
Airway History
Snoring or noisy breathing could indicate what?
- Snoring or noisy breathing could indicate:
- Adenoidal hypertrophy
- Upper airway obstruction
- OSA
- Pulm HTN
Airway History
Presence/nature of cough could indicate what?
-
Presence/nature of cough could indicate:
-
“Croupy” cough may indicate:
- subglottic stenosis
- previous tracheoesophageal fistula repair
-
Productive cough may indicate:
- bronchitis
- pneumonia
-
“Croupy” cough may indicate:
Airway History
Past episodes of croup could indicate what?
- Postintubation croup
- Subglottic stenosis
Airway History
Inspiratory stridor, usually high pitched, could indicate what?
- Inspiratory stridor, usually high pitched could indicate:
- Subglottic narrowing
- Laryngomalacia
- Macroglossia
- Laryngeal web
- Extrathoracic foreign body
- Extrathoracic tracheal compression
Airway History
Hoarse voice could indicate what?
- laryngitis
- vocal cord palsy
- papillomatosis
- granuloma
Airway History
Asthma and bronchodilator therapy could indicate what?
Bronchospasm
Airway History
Repeated pneumonias could indicate what?
- incompetent larynx with aspiration
- gastroesophageal reflux
- cystic fibrosis
- bronchiectasis
- residual tracheoesophageal fistula
- pulmonary sequestration
- immune suppression
- congenital heart disease
Airway History
Previous anesthetic problems, particularly related to airway, could indicate what?
- difficult intubation
- difficult mask ventilation
- failed or problematic extubation
Airway History
Atopy, allergy could indicate what?
- increased airway reactivity/resistance
- increased propensity to desat
Airway Assessment
History of a congenital syndrome could indicate…
Many are associated w/ DA management
Airway Assessment
Parents smoke in the house could indicate…
increased airway reactivity
History:
Resp focus
- Resp focus:
- Frequent URIs?
- History of wheezing?
- History of noisy breathing?
- Hospitalizations?
- History of intubations?
- History of eczema/skin allergy?
- In daycare?
- Immunization status?
- Smokers in the house?
- Infant: Frequent vomiting after feeds/“choking” episodes?
- Child: Frequent tonsillitis? Ear infections? Snoring?
History:
CV focus
- CV focus:
- Any family history of
- CHD/chromosomal abnormalities
- Sudden/premature death
- Maternal illness/infections (both chronic and during pregnancy)
- Maternal medications/drug use
- Any family history of
- Infant: Any problems with poor feeding, sweating (especially on the forehead) during feeding, poor weight gain, FTT, decreased activity level
- Older child/ adolescent: Any inability to keep up with the activity level of peers, need for frequent periods of rest, anorexia, cough, wheezing, rales, chest pain, leg cramps, syncope, light-headedness, palpitations; any history of drug use; any family history of sudden death, syncope, or arrhythmias
- Any changes in color or cyanosis when crying?
Physical Exam
- Always talk through assessment; children like to know what to expect; get on their eye level; stay calm
- Airway: inspect face (include profile view), mouth opening, tongue mobility (“stick out tongue”), neck extension, loose teeth
- Assess respirations in position of comfort (moms arms), look for flaring, retractions
- Auscultate heart and lungs
- Rales or wheeze? request a cough and listen again
- Murmur detected? further investigate- cyanosis, syncope, arrhythmias, tachycardia, poor feeding, activity tolerance
- Innocent murmurs are found in up to 50% of normal children (especially age 2 to 6)- these are systolic ejection murmurs & are accentuated by stress, anemia, fever
- Diastolic murmurs &/or symptomatic murmurs need investigation
- Palpate liver if any reason to suspect fluid overload: Normal liver is 1-2 cm below costal margin
- Hepatomegaly is a sign of RV failure
- Cyanosis in infant: Arterial desaturation or central cyanosis is best detected in perioral area, the mucous membranes of mouth, lips, and gums.
- Central cyanosis should be distinguished from peripheral cyanosis, which can occur in a cold environment, and acrocyanosis, which in newborns is d/t sluggish circulation in fingers and toes
Fasting Guidelines
- Clear liquids: Include only fluids w/out pulp, clear tea, or coffee w/out milk products
- Gum chewing: 70% ↑ in gastric fluid volume in first 15 min after initiating gum chewing, mostly saliva; most providers will proceed as long as gum is spit out (not swallowed)
- Clear liquids 2 hrs
- Breast milk 4 hrs
- Infant formula 6 hrs
- Solids (fatty/fried food) 8 hrs
Room Setup
- Range of sizes of airway equipment (face masks, OPA’s, ETT’s, LMA’s, blades)
- Appropriate size LMA should always be available even if intubation is planned in case of unanticipated difficult airway
- Straight blades most commonly preferred in infants d/t anatomical differences
- Appropriate sized BP cuff and pulse ox is present & functional
- Calculate drug doses, allowable blood loss, & fluid requirements
- Have primed bag of IV fluid ready and all supplies to start & secure IV set up & accessible
- Prepare pediatric circuit/ bag; Preset vent settings appropriate for size (& program in weight to anesthesia machine if applicable)
- Emergency drugs for every pediatric case:
- Weight appropriate doses of Sch & Atropine w/ a small gauge needle appropriate for IM injection
- Laryngospasm
- Syringe of propofol
- Facilitate intubation, break laryngospasm, increase depth of anesthesia quickly
- Epi diluted to 10 mcg/ml: not always drawn up but definitely consider drawing up in sick pt/ complex case
- Weight appropriate doses of Sch & Atropine w/ a small gauge needle appropriate for IM injection
- Plan for age appropriate distractions: have flavors for masks; consider parental presence if facility allows
- Warm room
Premedication
- Often needed at age ~10 months when separation anxiety becomes an issue
- Oral versed most common- SEE DOSING
- Severe distress/ need for profound sedation
- May combine meds (ketamine, atropine, versed combo PO)
- May use IM route if uncooperative w/ PO sedation
- Intranasal route is sometimes used but can really burn & make child more agitated
Mask Ventilation
- Sniffing position is critical
- Avoid pressure on soft tissue in submental triangle
- Jaw thrust
- Low threshold for 2-person ventilation
Induction
- Stay flexible! All monitors may not go on before induction (try for pulse ox); child may be afraid of mask
- Stay calm! Be warm and reassuring
-
Inhalational induction most common
- **Frequent monitoring of BP and HR during induction
- < 10 months: usually no premed required
- Alternative is pre-op IV w/ standard induction: topical anesthetics can be used for IV starts; EMLA cream onset is 45-60 min
- IM Ketamine rarely used for inductions in larger cognitively impaired/ extremely uncooperative children
- It is safest to maintain spontaneous ventilation for induction; taking over ventilation will increase risk of anesthetic overdose
Inhalation Induction
- Inhalational induction is common: seated or supine position
- One approach:
- Higher flows with 70% N2O and 30% O2
- Fully open APL
- Allow few breaths of N2O mix and then incrementally turn on Sevo to 8% (some providers turn up sevo to 8% w/out using incremental technique after few breaths of N2O- especially if crying)
- Turn off N2O to provide 100% O2
- Assist spontaneous ventilation PRN- caution about high inspired VA w/ assisted or controlled ventilation
- Obtain IV
- Once IV in, induction proceeds- give some propofol, narcotic, +/- NMB, etc at this point and then proceed w/ airway management appropriate for case (LMA, ETT); NOTE: intubation is often completed w/out NMB’s
- Be sure to turn down Sevo to normal MAC range for child; watch VS closely during induction
RSI in Children
- Same principle as adults to prevent aspiration
- Cricoid pressure in infants/ children is +/- (Barash says no); increased likelihood of obstructing an infants airway w/ little proven benefit
- Note that children will have rapid desat w/ hypoxia (limited reserve)
-
Equipment: ETT (pre-stylet) age calculated plus 0.5 smaller & 0.5 larger; laryngoscope (working), sxn immediately available at HOB, functioning IV, pre-drawn drugs
-
Propofol 2-4 mg/kg (stable) vs. ketamine 1-2 mg/kg or etomidate 0.2-0.3 mg/kg (unstable)
- plus Sch 2mg/kg (premed w/ Atropine 0.02 mg/kg)
- Consider Rocuronium 1.2 mg/kg if Sch contraindicated (45 to 75 min duration)
- Calcium (IV) should be immediately available in the event Sch leads to unanticipated hyperkalemia w/ ventricular arrhythmias
-
Propofol 2-4 mg/kg (stable) vs. ketamine 1-2 mg/kg or etomidate 0.2-0.3 mg/kg (unstable)
Airway Management
- Always have ranges of ETT sizes (0.5 smaller than calculated & 0.5 larger)
- Short trachea favors right mainstem intubation
- Breath sounds often referred
- Common formula over 2 yo
- (Age + 16) / 4
- Cuffed tubes are fine as long as cuff pressures are monitored- use ID 0.5 mm smaller tube
- Rough estimate of depth is 3x ID
- A leak should be maintained around cuff regardless @ 20-30 cm H20
Where should the ETT be located on CXR?
Midway b/t cords and carina
LMA use
- Used during routine surgeries & as a rescue device for failed intubation
- Low failure rate for insertion (< 1%)
LMA Contraindications
- Contraindicated in children w/ r/f pulmonary aspiration
- Other specific pediatric contraindications:
- Mediastinal masses
- Children requiring high peak airway pressures to ventilate
- Tracheomalacia
- Very limited mouth opening
Laryngeal Mask Sizes and Weights
- 1: < 5 kg
- 1.5: 5-10 kg
- 2: 10-20 kg
- 2.5: 20-30 kg
- 3: 30-50 kg
- 4: 50-70 kg
- 5: 70-100 kg
- 6: >100 kg
ETT Size, cuff pressure monitoring
- 95% of subglottic stenosis is acquired
- Post-intubation injury most common cause of acquired subglottic stenosis
- Avoid oversized ETT’s
- Cuff pressures must be monitored throughout long cases/ extended intubations
- Maintained at a level below 20-30 cm H2O
Risk factors associated w/ acquired SGS:
- Risk factors associated w/ acquired SGS:
- Trauma during intubation
- ETT movement during intubation
- Prematurity
- Presence of infection at time of intubation
Ventilation
- 6 to 8 mL/kg is typical
- Sustained plateau airway pressures > 35 cm H2O can lead to barotrauma:
- PTX
- pneumomediastinum
- subq emphysema
- Lung protective strategies apply
Laryngospasm
- More frequent in infants; risk decreases w/ increasing age
- Reflex closure of false & true vocal cords
Symptoms of laryngospasm
- Stridor
- Retractions
- Flailing of lower ribs
- “Rocking horse” chest wall movement
- Stridor will be absent with complete closure = “silent inspiratory effort”
- Can lead to profound bradycardia & desat if unrelieved
Laryngospasm risks
- Recent URI
- secondhand smoke
- stimulation while “light”
- secretions in airway
Laryngospasm treatment
- Continuous positive airway pressure
- 100% O2
- jaw thrust at mandibular condyles
- sxn secretions
- Deepen anesthesia (propofol)
- Unresolved?
- Atropine & Sch- if no IV access then give IM
- Can lead to negative pressure pulmonary edema especially in healthy, muscular adolescents- may have to remain intubated for 12-24 hrs & may need furosemide
What is the leading cause of bradycardia in children?
Hypoxia
“Other” causes of bradycardia in children
- Vagal stimulation
- Increased ICP
- CHD
- Hypothermia
- Air emboli
- Tension PTX
- Meds
- single dose Sch
- clonidine, beta blockers, Sevo esp in downs syndrome, propofol infusion syndrome, some eye drops
Bradycardia in infants
< 100 bpm
Bradycardia in 1-5 yo
< 80 bpm
Bradycardia in >5 yo
< 60 bpm
Treatment for bradycardia in children
- Treat cause: think oxygenation and ventilation first!
- Atropine if vagal origin 0.02 mg/kg IV
- Epinephrine if decompensated 10 mcg/kg
3 phases of emergence
- 3 phases:
- Early phase: coughing intermittently, gagging, struggling, moving nonpurposefully
- 2nd phase: apnea, agitation, straining, breathholding
- 3rd (final) phase: regular RR, purposeful movement, coughing, eyes open spontaneously- extubation now appropriate
Position of transport/recovery
- Transport in lateral decubitus position “recovery position”
Emergence
PACU complications
- PACU complications in ~5% of children:
- Vomiting 77% (more common in > 8 yo)
- Airway compromise 22% (more common in < 1 yo)
- CV compromise is < 1%
Emergence
- Neuromuscular function: check & reverse if appropriate
- Different techniques for extubation: always prioritize patient safety
- Awake extubation: must be awake & purposeful; laryngospasms happen when pts are extubated in early & 2nd phase, “if in doubt…don’t take it out!”
-
Deep extubation: Sevo increased to 1.5-2 MAC for at least 10 min
- Ensure no response (cough, breath holding) to suctioning or tube movement & ensure regular respirations
Regional Anesthesia
-
Caudal anesthesia
- Lower abdominal & LE surgery in <5-6 yrs of age
- Single shot block w/ LA will last 4-6 hrs
- Done following GA induction in lateral position
- Epidural & spinal anesthesia also used in children but are most frequently completed under general anesthesia
- Technique similar to adult
Increased risk of PONV in children in certain surgeries:
- Hernia
- Orchidopexy
- T&A
- Strabismus
- Middle ear
- Laparoscopic
Prevention of PONV in children
- Prevention: hydration, multi-modal analgesia (opioid sparing)
- Typical 2 agent strategy for prevention in at-risk (decreases risk by 80%):
- Ondansetron 0.05-0.15 mg/kg IV (note risk in undiagnosed long QT syndrome)
- Dexamethasone 0.0625-1 mg/kg IV
Population of children w/ peak incidence of PONV
Females
Age 10-16
Emergence Delirium
- Phenomenon characterized by non-purposeful restlessness and agitation, thrashing, crying or moaning, and disorientation
- 18% of all children undergoing surgery and anesthesia develop emergence delirium
Factors that affect incidence of emergence delirium:
- young age
- previous surgery
- type of procedure
- type of anesthetic
- level of preop anxiety is predictive
What age does emergence delirium peak?
Age 2-6 years
Emergence delirium is most common with what?
Most common after Sevo (then Des)
How long does emergence delirium last?
- Usually lasts ~ 10-15 min
- Protect from self-harm
