Age-Related Considerations for Anesthesia & Analgesia Flashcards
What are neonatal, pediatric, and geriatric patients?
NEONATAL = up to 4 weeks
PEDIATRIC = up to 12 weeks
GERIATRIC = greater than 75-85% of breed/species life expectancy
How does age and size contribute to anesthesia risk?
- cats under 6 months have a lower risk of mortality
- smaller dogs (<5 kg) and cats (<2 kg) have a higher risk of mortality
Why are smaller patients at a higher risk for mortality?
- shivering and increased oxygen consumption
- monitoring challenges
- IV access
- airway management challenges
How does the cardiovascular system develop upon birth? How can this affect anesthesia?
BIRTH = increased SVR and decreased PVR, which causes a reversal of blood flow through PDA and closure of foramen ovale
changes are not anatomical for several weeks and hypoxemia or acid base imbalances from anesthesia can cause re-opening of fetal circulation due to an altered PVR
What determines MAP? CO? SV?
MAP = CO x SVR
CO = SV x HR
SV = inotropy x afterload x preload
What is especially poorly tolerated in the neonatal cardiovascular system? What does this result in?
bradycardia —> CO is rate dependent
- low pressure and SVR
- poor ability to vasoconstric
How does the pediatric SNS affect reaction to anesthetic drugs?
underdevelpment = poor response to inotropes and vasopressors
Other than bradycardia, what else is poorly tolerated in pediatric patients?
blood loss greater than 5 mL/kg —> hematopoiesis poor until 2-3 months
What are 4 differences in the pediatric respiratory system? How are they addressed for anesthetic procedures?
- large tongue + narrow airway = higher airway resistance
- FRC closer to or lower than CC = atelectasis
- high lung and chest wall compliance
- higher RR = tissue oxygenation demand higher
respiratory depressants have a profound negative effect —> supplemental oxygen and ventilatory assistance helpful
What is the pediatric hepatic system like? How does this affect anesthesia?
- immature microsomal enzyme system = drug metabolism and transformation not fully functional until 8 weeks
- minimal glycogen storage = supplemental glucose needed for longer procedures
- low plasma albumin = increased impact of protein-bound drugs
What is the pediatric renal system like?
reduced function until 6-8 weeks = cannot tolerate large volumes given rapidly and not as able to concentrate urine
What is hydration, temperature regulation, and BBB like in pediatric patients?
higher TBW and ECF volume = dehydration happens rapidly at smaller volume losses
low SQ body fat and high SA:body mass = hypothermia
increased permeability = lower anesthetic drug dose needed
What fasting is required in neonatal/pediatric anesthesia? What is necessary before performing anesthesia?
<2 hr or none at all - low glucose stores! (6 hr at most)
accurate BW day of procedure
What are important aspects of neonatal/pediatric anesthesia?
- dilute drugs for accuracy
- use reversible drugs
- pre-emptive analgesia including local blocks
- monitor HR and aggressively treat bradycardia
- avoid blood loss, be careful with fluid administration (immature renal function)
- monitor pulse ox and supplement oxygen
- prevent, avoid, and treat hypothermia
- keep anesthesia time to the shortest possible duration
What are the main 8 things that make anesthetic events difficult for puppies and kittens?
- handling can cause excitement at induction
- easy to traumatize soft tissue with intubation
- challenging IV access
- HYPOTHERMIA
- hypoglycemia
- bradycardia
- monitors do not work well due to size
- jaw tone and palpebral reflex not goof indicators of depth at this age —> rely on monitors and physiologic values
Is ketamine commonly used in neonates/pediatric patients?
may not be as useful due to underdeveloped NMDA receptors, but is is still a useful adjunct in reducing inhalant requirements
How do opioid effects differ in neonates/pediatric patients?
sedative and respiratory depressant effects are more profound, but they still remain a mainstay for analgesia and anesthesia —> monitor closely
What 3 drugs are avoided in neonates/pediatric patients?
- Acepromazine
- alpha-2 agonists
- Doxapram - can worsen cerebral hypoxia (just intubate!)
Why an analgesia especially important in neonates/pediatric patients? When are NSAIDs able to be used?
brief painful procedures can alter pain tolerance later in life
- DOGS = 10-12 weeks
- CATS = 4-5 months
What are the 4 most important monitors for procedures done in neonates?
- BG every 1-2 hrs
- HR
- temperature
- BP - doppler for smaller patients
What blood pressures are acceptable in neonates/pediatric patients?
<8 weeks - SAP > 70 mmHg, MAP > 50 mmHg
8-12 weeks - SAP > 80 mmHg, MAP > 55 mmHg
What must be closely monitors during recovery of neonatal/pediatric patients?
temperature and oxygenation —> get them up, eating, and maintaining body temp ASAP
How does the geriatric patient physiology differ compared to other patients?
- reduced blood volume, CO, baroreceptor activity, and autoregulation of blood flow = decreased cardiac reserve and ability to maintain BP + more rapid inhalant onset and impact
- decreased lung elasticity
- decreased RR, tidal volume, MV
- decreased O2 consumption and CO2 production
- decreased O2 diffusion capacity
- decreased respiratory muscle strength, chest wall compliance, elastic recoil, vital capacity, and protective airway reflexes
HYPOXEMIA + HYPOVENTILATION
What pre-procedure patient assessment should be added in geriatric patients?
- changes in weight, activity, appetite, or behavior
- current medications, what was given in the morning
- thorough PE
- blood work + other diagnostics
What are the 4 ideal parts of pre-anesthetic diagnostics for geriatric patients? What should be added in patients with history of cardiac disease?
- PCV and TS day of
- UA, CBC, Chem (+ T4) within 6 months, if abnormal repeat
- thoracic radiographs within 6 months
- BP in cats +/- dogs
updated thoracic radiographs and echo if unstable
What is the current AAHA recommendation for blood work before a procedure for geriatric patients? What should be done if diagnostics have been done within 6 months and the patient has no changes in health status?
screening CBC and chemistry within 2 weeks of an anesthetic event
repeat if there is a history of abnormalities, based on health status, procedure to be performed, and prior results
How is anxiety approached in geriatric patients? What fasting is recommended? Why is hydration evaluation especially important?
older cats and dogs are often more anxious in hospital and can benefit from at-home sedation - Trazadone, Gabapentin
consideration of breed, pre-exisiting disease, etc - no longer than 8 hours
these patients are not as readily mobile
Why is hypotension risk increased in geriatric patients? What is done to combat this? What is avoided?
increased sensitivity to negative effects of inhalants coupled with reduced cardiac reserve
analgesic CRIs (+ dopamine/dobutamine) and local/regional anesthesia to reduce inhalant requirements
too many boluses of IV fluids —> pre-existing disease common, especially cardiac disease
When is hypotension treated in geriatric patients? How?
SAP < 85 mmHg, MAP < 65 mmHg
- treat bradycardia
- decreased inhalants, add/increase CRI
- IV bolus when appropriate (no cardiac disease)
- pressors or inotropes
When is hyp0ventilation investigated and treated?
> 50 mmHg
What should be done when a geriatric patient is recovering slowly? When is this especially common?
- check HR and rhythm, pulse quality, BP, RR, MM color, and CRT
- confirm airway is protected, especially is brachycephalic or laryngeal paralysis
- stop inhalant and injectables
- stimulate patient - check jaw tone, pinch toes, change recumbency
- check ETCO2 for hypoventilation
worsened cognitive function
What is considered when determining drugs to use in geriatric patients? How are drugs adjusted?
pre-existing renal, hepatic, endocrine, neurologic, and cardiac disease
- reducing drugs with multimodal analgesia (local and regional anesthesia!)
- reduce inhalants
When can NSAIDs be used in geriatric patients?
CAREFULLY - must be hemodynamically stable, adequately hydrated, and otherwise healthy
- consider looking at history of use of NSAIDs - any adverse reaction or undesired responses
