Flashcards in Pediatric Anesthesia Week 4 Flash Cards Deck (110):
This is most reliable parenteral route for medications
How slow would you want to administer Vancomycin in a pediatric patient? What would the patient be at risk for if you administer too quickly?
- At least over 1 hour
- Redman Syndrome
How slow would you want to administer Gentamicin in a pediatric patient? What you the patient be at risk for if you administer too quickly?
- At least over 30 minutes
- Hearing loss
With intramuscular (IM) injections, which muscle has the faster absorption rate?
Deltoid (quicker than when administered in the thigh)
Which route would be useful in emergency situations should IV or IM not be available? What medications can be administered this route? Why is it useful?
- Epinephrine or Atropine
- Rapidly absorbed
When is medication by oral route (PO) contraindicated with pediatric patients?
- If a GI dysfunction exists like vomiting
__________ route is rapidly effective, however, is not well tolerated in children.
What procedure is intranasal route great after the child is anesthetized & does not require a peripheral IV?
Myringotomy (insertion of tympanostomy tubes)
How do children exhibit different pharmacokinetics from adults?
- Lower PROTEIN binding (more free drug = greater effect)
- Larger VOLUME of DISTRIBUTION (Vd) (require larger loading dose of WATER-SOLUBLE medications to achieve clinical effect)
- Smaller PROPORTION of FAT and MUSCLE stores (less redistribution into muscle/fat mass = large initial blood concentration)
- Immature RENAL & HEPATIC function (less metabolism & elimination)
What drugs will have a larger volume of distribution in the infant compared with the adult?
WATER-SOLUBLE drugs will have a larger volume of distribution in an infant compared to an adult
What drugs will have a smaller volume of distribution in the infant compared with the adult?
LIPID-SOLUBLE drugs will have a smaller volume of distribution in an infant compared to an adult
True/False: Given children exhibit different pharmacokinetics, they may reduce a drug's metabolism and/or delay elimination and, in some cases, may increase metabolism.
What is Kernicterus?
Bilirubin Encephalopathy caused from too much unconjugated bilirubin in the body either from:
- Immature liver unable to process or conjugate bilirubin
- Medications that are protein-binding competitive
Why is there an increases sensitivity in neonates to most sedatives, hypnotics, and narcotics?
May be in part related to INCREASED BRAIN PERMEABILITY from an incomplete myelination allowing non-lipid soluble medications to enter (an immature blood brain barrier)
Do volatile concentrations increase more rapidly or slowly in alveoli of children? What else does that mean?
- Increase more RAPIDLY
- Quick on, quick off
Rapid alveolar volatile concentration result in...?
- High level alveolar ventilation (Va) in relation to FRC
- Higher proportion of vessel-rick tissue that rapidly equilibrate with blood levels
- Lower blood-gas partition coefficients of volatile anesthetic in infants
When is N2O contraindicated? When should be avoided and why?
- With any procedure with gas-filled cavities
- Obstructed bowel
- Gas "bubble" within the eye
- ETT cuff
- Bubbles in veins
- Avoid N2O in emetogenic surgery
- Middle ear surgery
What is hyperoxia?
One of many factors causing Retinopathy of Prematurity (ROP)
What group of pediatrics are at high risk for Retinopathy of Prematurity (ROP) if O2 is excessively administered?
- LESS than 1500 grams
- LESS than 28 weeks gestation
What is the recommended dose for O2 to avoid hyperoxia?
Blend air w/ O2 to maintain SpO2 of 90 to 95%
What are the standards in administration for a Urine Pregnancy Test?
- 12 years of age or older
- Menstruating (child-bearing years)
Tell me about Halothane with pediatrics?
- Smooth & rapid inhalation
- Pleasant odor
- CAUSES BRONCHODILATION
- Causes CEREBRAL VASODILATION
- Produces MODERATE MUSCULAR RELAXATION
**Can cause Halothane Hepatitis (contraindicated in children with history of unexplained post-halothane jaundice
What should you monitor for with Halothane?
- Cardiac arrhythmias
- Cardiac output depression (bradycardia)
- Reduction in arterial blood pressure
- Limit epinephrine to < 1.5 mcg/kg when administering Halothane (increases incidence of arrhythmias)
Tell me about Isoflurane with pediatrics?
- NOT APPROPRIATE for inhalation induction
- PUNGENT odor
- IRRITATES airway reflexes, causing LARYNGOSPASM, BREATH HOLDING, and COUGHING
- Profound respiratory depressant
How effect does rapid administration of Isoflurane concentration have on a patient?
DECREASES BP, HR, and RR
Isoflurane, like Desflurane, (does/does not) react with desiccated soda lime or Baralyme to release _____ _______ into the breathing circuit.
- DOES REACT
- Carbon Monoxide
Tell me about Desflurane with pediatrics?
- Very low blood solubility
- Cardiovascular effects are similar to Isoflurane
- NOT APPROPRIATE for inhalation induction
- VERY PUNGENT odor
- AIRWAY IRRITANT causing LARYNGOSPASM, BREATH HOLDING, and COUGHING
How is emergence if Desflurane is used? What are they at risk for?
- Desflurane has a very rapid emergence, increasing risk for delirium, particularly if pain is present
- Emergence delirium
Tell me about Sevoflurane with pediatrics?
- EXCELLENT for inhalation induction
- Pleasant odor
- Does not cause airway irritation
- Cardiovascular effects are similar to Isoflurane
- Hydrolyze to form neprhotoxic Compound A
How is emergence if Sevoflurane is used? What are they at risk for?
- Emergence is smooth and rapid
- Also at risk for Emergence Delirium, particularly if pain is not well controlled and HIGH LEVELS of sevoflurane were given throughout the case
What is the treatment for Emergence Delirium?
Propofol to put them back to sleep and have them awake slowly
What is Emergence Delirium?
- A dissociated state of consciousness in which patients are inconsolable, irritable, uncompromising, and/or uncooperative
- Many do not recognize and respond to their parents
What is the incidence of Emergence Delirium? With which agent is incidence the lowest? What age is at highest risk? How do you minimize it?
- 2 to 80%
- Less prevalence with Halothane
- Ages 1 to 5
- Appropriate pain relief
List eight risk factors for Emergence Delirium in children?
1. Age of less than 5
2. Volatile agent used (SEVO, ISO, and DES increase risk)
3. Type of surgery (Ophthalmologic 28%, Otolaryngologic 26%)
4. Rapid emergence
*5. PREOPERATIVE ANXIETY
6. Child temperament (poor socialization, low adaptability scores
7. Adjunct medication (opioids)
8. Inadequate pain relief
What can trigger Malignant Hyperthermia?
ALL potent INHALATION ANESTHETICS
What is the treatment for MH?
Dantrolene 2.5 mg/kg
When compared to adults, infants dose of Succinylcholine tend to be....? Why?
- Require a relatively HIGH dose of Succinylcholine
- Do to the large ECF compartment and are MORE RESISTANT to its NEUROMUSCULAR EFFECTS
Which two diagnoses are Succinylcholine contraindicated in pediatrics?
MH susceptible and Duchenne Muscular Dystrophy
When can Succinylcholine be used?
Should be reserved for emergency intubation and during Laryngospasms or for IM route should IV not be available
What is the dose for emergency IV Succinylcholine? IM?
0.1 mg/kg IV or 4 mg/kg IM
What is "Trimus"?
An increase in Masseter muscle tone infrequently associated with Succinylcholine.
**When should do you AVOID Succinylcholine in pediatric patients?
- Any EYE trauma (increases intraocular pressure)
- With burns (greater than 24 hours old)
- Massive trauma,
- Major neurologic/neuromuscular disease
- Renal failure compounded by neuropathy
- Elevated K serum levels
- Bradycardic patients
How much does serum K+ concentration increase after administration
1 mEq/L or less
Cardiac wise, how can a single dose of Succinylcholine effect the heart? What can you administer prior to?
- Can cause occasional BRADYCARDIA, even ASYSTOLE
- ATROPINE IV
What is the normal Atropine dose prior to administration of Succinylcholine in children?
10 to 20 mcg/kg IV
20 to 40 mcg /kg IM
What THREE factors cause preterm and full-term neonates and infants who are small for gestational age lose heat quickly?
1. They have a large skin-surface area compared to body mass ratio
2. Increased thermal conductance (thin layer of subcutaneous fat)
3. Increased evaporative heat loss (reduced keratin content on skin)
The combination of what TWO factors predisposes infants to hypothermia?
- Increased heat loss
- Diminished efficacy of the THERMOREGULATORY response (reduced ability to generate heat)
What TWO types of heat loss contribute the most to perioperative heat loss to the environment?
RADIATION and CONVECTION
During the first hour of general anesthesia a different mechanism contributes to intraoperative hypothermia, what is it?
Rapid decrease in core temperature is from CORE-to-PERIPHERAL redistribution of body heat
What are the FOUR primary processes of heat loss?
What is the most significant mechanism of heat loss in our bodies, especially under anesthesia? Which part of the body loses the greatest amount of heat via this mechanism?
How is radiation of heat defined? How much do we lose?
- The transfer of energy between 2 objects that are NOT IN DIRECT CONTACT, but differ in temperature
How is convection defined? How much do we lose?
- The process of creating air current by heat.
Think currents (i.e. wind chill factor
Approximately what percent of total heat loss from the body normally occurs by radiation and convection combined?
70% (40% via radiation and 30% by convection)
How is heat loss by evaporation defined? Who experiences this?
- Includes moisture evaporated from the skin as well as through the patients respiratory tract (i.e. exhaled water vapor (usually NOT a high heat loss with adults, but in kids))
- Patient that sweat or prepped with liquids experience heat loss via evaporation
Through which route does a burn patient lose the highest percentage of body heat?
Heat loss via EVAPORATION
How is heat loss by conduction defined?
- The transfer of heat by physically touching a less warm object. TWO objects MUST BE IN DIRECT CONTACT where heat exchange occurs (entropy)
Heat is lost from the body by radiation, convection, evaporation, and conduction. Rank these mechanisms from greatest to least heat loss?
Radiation > Convection > Evaporation > Conduction
How do we as anesthesia providers prevent loss of heat in our patients? Why?
- Forced warm air devices
- Lower gas flow rates
- Humidification systems
- Warming the OR (to 24 degrees centigrade (75F)
- Covering and insulating
- IV fluid warmer
- Use a esophageal (lower third) or rectal temp probe
*To decrease higher morbidity experiences by hypothermic patients
What do infants rely on in order to generate heat?
Non-shivering thermogenesis via BROWN ADIPOSE TISSUE
What is brown adipose tissue? Function?
- A collection of mitochondria that converts fat into heat. Highly vascularized and innervated with SYMPATHETIC nerve fibers
- Primary thermoregulatory control (heat) in infants
Where is brown adipose tissue located?
- Around the kidneys/adrenal glands
When does non-shivering thermogenesis occur?
Occurs within hours of birth and may persist up to 2 year of age
What is the significance of brown adipose tissue? Where is it located?
- Increases norepinephrine production enhancing metabolism
- Located in the interscapular space and around large blood vessels, neck, substernum, and around kindeys and adrenals
State four reasons why it is so difficult to keep newborns warm?
1. Readily lose heat due to their large surface area to body weight ratio
2. Cannot compensate by shivering
3. Have limited subcutaneous fat for insulation
4. Have limited stores of brown fat and unstable thermoregulatory systems
By which mechanism do infants lose most of their body heat?
Newborns produce heat primarily by what mechanism?
Non-shivering thermogenesis via brown adipose tissue metabolism
What controls non-shivering thermogenesis in infants?
The AUTONOMIC NERVOUS SYSTEM
What is the best way to maintain an infant's body heat? What is the best way to warm an infant in the OR?
- Maintain high ambient temperature
- Increase the OR temperature
Premature infants may require what ambient temperature to maintain a normothermic state?
26 degrees Celsius (about 75 degrees F)
_____thermia appears to be far more dangerous than a comparable degree of _____thermia.
- Hyper (hyperthermia)
- Hypo (hypothermia)
What can cause hyperthermia in the OR?
- Overuse of heat-conserving measures
- Pyrexial reactions (from manipulation of an infected organ or blood transfusion reaction)
- Very rare, can by caused by MALIGNANT HYPERPYREXIA SYNDROME
At what temperature do you want to stay below?
No GREATER than 37.7 degrees celsius
At what age does an infant's posterior fontanelle close? Anterior fontanelle?
- Posterior fontanelle closes at FOUR MONTHS of age
- Anterior fontanelle closes at 9 to 18 MONTHS of age
What can palpation of an infant's fontanelles assess?
- Hydration status
- Intracranial pressure
- Increase PaCO2
In sick newborns how is cerebral blood flow regulated?
CBF is pressure related, not autoregulated
What factors predisposes infants to intracranial hemorrhage?
- Fluctuations in arterial/venous pressure or CBF
- Low hematocrit
- Overtransfusion or rapid administration of hypertonic fluids (Dextrose / Bicarb)
What is the incidence of Retinopathy of Prematurity? What is the relationship between ROP and birth weight/ gestational age?
- Occurs in approximately 50% of extremely low birth weight infants (preterm infants)
- Inversely proportional (decrease risk of ROP if increase birth weight and gestational age)
What is another name for Retinopathy of Prematurity?
What causes ROP?
Unknown. One theory holds that the combination of hyperoxic VASOCONTRICTION of retinal vessels, induction of vascular endothelial growth factor, and free oxygen radicals DAMAGE THE SPINDLE CELLS IN THE RETINA
How do we decrease the risk for ROP?
Use the lowest inspired O2 concentration that provides SpO2 between 92% and 96% to avoid significant fluctuations in O2 saturations
What is ROP associated with? (factors that increase incidence)
- Neonatal O2 exposure
- Blood transfusion
- Fluctuation in levels of CO2
At what gestational age does the risk of Retinopathy of Prematurity (ROP) become negligible? Why?
- After 44 WEEKS post-conception (11 months)
- Because retinal vasculogenesis is complete between 42 to 44 weeks post-conception
Neonatal Retrolental Fibroplasia is a result of oxygen toxicity above what FiO2?
GREATER than 40% (but some say safest at room concentration)
What is Bell's Phenomenon? What is it indicative of?
- If the eye is irritated or exposed to noxious stimuli, the eyes roll upward
- "Light" anesthesia
What can upper respiratory infections increase risks for during anesthesia?
- Increase airway sensitivity to noxious stimuli
- Arterial O2 desaturation
- Breath holding
- Severe coughing
Which symptoms can a child proceed with anesthesia for a procedure?
- Uncomplicated URI
- Clear secretions
- and is otherwise healthy
Which symptoms should a child be postponed for an elective procedure? How long?
With more severe symptoms: (postpone 4 to 6 weeks)
- Mucopurulent secretions
- Productive cough
- Pyrexia GREATER than 38 degrees Celsius (100.4F)
- Pulmonary involvement
- If bacterial infection is suspected (appropriate antibiotics)
- Present comorbities (asthma, cardiac disease, etc.)
Which airways are associated with fewer episodes of respiratory events with URI's?
Mask ventilation and LMA's (less than ETT's)
How would you extubate and emerge pediatric patients with URI's?
Deep extubation w/ suctioning
Asthma is a common ....?
Chronic OBSTRUCTIVE disorder of the airways
What is the treatment of an intra-operative bronchospasm?
- Deepen anesthesia/analgesia
- Increase FiO2
- Increase expiratory time (1: 2.5)
- Repeat B2 agonist
- If severe, give small doses of Epinephrine 10 to 20 mcg IV or via ETT)
What is Cystic Fibrosis?
Autosomal recessive disorder (requires 2 copies of a gene mutation). Disruption of electrolyte transport in epithelial cells in sweat ducts, airway, pancreatic duct, intestine, biliary tree. Leads to viscous mucus production, lung disease, intestinal obstruction, pancreatic insufficiency, and biliary cirrhosis
What do you want to avoid giving in CF patients?
Avoid any extra GLYCOPYRROLATE
What are some anesthesia consideration in patients with CF?
- Give anxiolytics
- Hydrate well
- Give nebulized saline treatment prior to and after surgery
- Circuit humidifier, optimize ventilation with FiO2
- Expect high airway pressure (careful with barotrauma/pneumo)
- Suction ETT under DEEP ANESTHESIA
- Complete reversal of NMB BUT AVOID EXTRA GLYCO
What is the appropriate internal diameter of an ETT for the premature newborn? For the full-term newborn?
- Premature newborn: 2.5 to 3.0 mm UNCUFFED
- Full-term newborn: 3.0 to 3.5 mm UNCUFFED
What ETT size and length are required for the neonate? 2 year old? 6 year old? 10 year old?
Neonate: 3.0 to 3.5 (uncuffed) at 10 cm
2 year old: 4.5 (uncuffed) at 12 to 13 cm
6 year old: 5.5 (uncuffed) at 15 cm
10 year old: 6.5 (uncuffed) at 17 cm
*Reduce by 0.5 for cuffed sizes
How do infants react to hypoxia?
They react with BRADYCARDIA progressing to cardiac arrest
How many breaths per minute should be produced by the ventilator for the neonate? For the adult?
- 30 to 50 breaths per minute for the neonate
- 12 to 16 breaths per minute for the adult
What are two advantages of using Randal-Baker masks in pediatric anesthesia?
- Designed to fit the facial contours more closely
- Reduce the size of dead space (firm rubber)
What is the intrapleural pressure (in cmH2O) generated during the first breath of neonatal life?
A distending pressure of 40 to 80 cmH2O
The adult lungs comprise of about 300 to 480 million alveoli, how many alveoli comprise the neonatal lungs? When do they form? Up to how old?
- 30 million alveoli (approximately 1/10th of the adult lungs)
- Most form by 18 months, continues until 8 years of age
What are the angles of the left and right bronchi in a child less then 3 years of age?
Left Bronchi: 55 degrees
Right Bronchi: 25 to 75 degrees
Why is subglottic stenosis potentially more severe in the pediatric patient than in the adult? What size ETT should you use?
- Relatively small cross-sectional area than in the adult
- Should use an ETT 0.5 size down
In newborns, the closing capacity is higher than the FRC, what does this mean?
Some airways close during the expiratory phase of normal tidal breathing
What factors contribute to the decreased functional residual capacity (FRC) in the neonate and infant during general anesthesia?
- Chest wall is less rigid (more compliant)
- Permits less elastic recoil due to the boxlike configuration of the infants thorax
- More vulnerable to muscle fatigue, decreasing stability
- Infants chest wall is extremely compliant, but with poorly compliant lungs leads to decreased FRC.
How is deadspace calculated in children? What is the deadspace of a 30 kg child?
- Deadspace is 2.0 to 2.5 ml/kg
- 30 x (2 or 2.5) = 60 ml of deadspace
What is the tidal volume of a neonate in ml/kg?
7 ml/kg (normal 6 to 8 ml/kg)
What is the minute volume per kg for a neonate?
Tv is 7 ml/kg and RR is 30 to 50 bpm
MinVolVent= Tv x RR
210 to 300 ml/kg/min (250 ml/kg/min is reasonable)