Supportive Care and Fluid Therapy Flashcards
define supportive care
non-pharmaceutical methods to enhance the quality of care the patient receives, including thermal support, padding and positioning, eye protection, and management of oral secretions and regurgitation
how does heat loss occur? 4 mechanisms
radiation: most important
-heat generated in body is given off to atmosphere
conduction:
movement of heat from the body to a surface it is in contact with
convection:
a fluid (air or water flowing by the skin carries away heat (wind chill)
evaporation: of liquid (sweat) promotes heat loss from skin surface
describe normal thermoregulation
the body normally maintains its temp within 0.2 degrees celsius of normal when not anesthetized
response to cold: shivering and peripheral vascocontstriction
response to heat: sweating, panting, vasodilation
describe thermoregulation and anesthesia
- gen anesthesia depresses thermoregulation
- increases interthreshold range from +/- 0.2 to +/- 3.5!!
- hypothermia promoted by:
-cold operating rooms
-room temp scrub solutions
-room temp IV fluids and lavage
-contact with cold surgery tables
-heat loss to airway by admin of cold and dry gases
describe adverse effects of hypothermia
- increased infection rates
- prolonged recovery
- decreased anesthetic requirements
- cold discomfort
- increased viscosity of the blood: increases workload of heart
- abnormalities in coagulation
- arrhythmias
- cardiac arrest
describe prevention of each type of heat loss
radiation:
1. blankets: keep non surgical surface area of patient covered
2. warm opterating rooms
conduction:
1. ensure always a pad or blanket between the patient and the table
2. keep patient protected from other cold surfaces
convection:
1. warm scrub/lavage fluids
2. no fans in operating room
evaporation:
1. ensure patient stays as dry as possible at all times
2. only scrub areas that are required to be scrubbed
3. heat and moisture exchange devices
describe active warming
- forced air warming devices (bear hugger)- most common!
- circulating warm water blankets; can get holes though and patient is covered in water
- conductive polymer blankets: HotDog; pretty safe as long as towel between device and patient is kept dry
dangerous!!
1. microwaved objects!!- okay for awake patients that can get off if too hot, but NOT for anesthetized patients
2. warm fluid bags
3. microwavable discs
4. heating blankets designed for humans
describe hyperthermia and anesthesia
less frequently a concern than hypothermia
causes: often iatrogenic
1. overzealous active warming of patients
2. opioids
3. malignant hyperthermia; was in pigs, has mostly been bred out
describe padding and positioning
- most procedures requiring anesthesia place the patient in an abnormal position for a prolonged period of time (dorsal recumbency)
- inadequate padding and unnatural positioning can lead to post-anesthetic patient discomfort, wounds, myopathies, and neuropathies
- most concerning in: very large patients (horses, cattle), and patients without inherent padding (emaciated patients)
- ensure ample padding that is applicable to the individual:
-thinner pads or blankets are sufficient for small anima; patients
-10-15cm thick pads for large animals - place extremities and joints in a natural position if possible:
-avoid extreme extension or flexion of the legs
-ensure that the patient isn’t resting on top of the tail - pull dependent forelimb cranially in large animal patients to avoid radial nerve injury!
describe eye protection (why needed and consequences if not)
- patients are unable to protect their own eyes under anesthesia
-eyelids are often open
-patients do not blink while under anesthesia
-may have forced air warming device blowing dry air onto the cornea
-cornea may come into contact with towels, drapes, and surgery tables - common consequences of general anesthesia:
-corneal ulcerations and/or perforation
describe methods of protecting they eye
- frequent application of eye lubricant
- closing eyelids when possible
- taping the eyes shut: especially if surgeon is working around the head
describe management of saliva
- ruminant patients continue to produce saliva throughout anesthesia
- the pharynx should be elevated such that saliva goes forward and out of the mouth
- saliva entering the trachea can cause resp difficulty and if severe could lead to post op pneumonia
- if possible, the oral cavity can be suctioned periodically to remove saliva
why does regurgitation occur in patients under anesthesia? (3)
- relaxation of esophageal sphincters
- manipulation of abdominal contents
- dorsal positioning of the patient
what complications can result from regurgitation?
- esophageal stricture due to damage caused by acidic stomach contents
- pneumonia caused by aspiration of gastric contents
- nasal and pharyngeal irritation
describe prevalence and reduction of regurgitation
- most frequently documented peri operative GI complication
- progression to aspiration pneumonia is 0.17%
- give antacids to make stomach contents less acidic, begin several days pre op for effect
- metaclopromide and cisapride decrease incidence but do not completely prevent regurg
-cerenia/metaclopramide does NOT decrease regurg!
describe regurgitation management during induction and operation
- observe patient diligently throughout premedication, induction, maintenance, and recovery
- capture airway rapidly after induction and inflate cuff appropriately
- recheck tube placement and cuff inflation frequently
- when regurgitating: keep head tipped down to encourage drainage of reflux out of the mouth as opposed toward airway (+/- suction)
describe regurgitation management during recovery
- examine oral cavity and pharynx prior to extubation
- lavage esophagus when regurg has occurred
- extubate the cuff partially inflated (squeegee contents out with it)
- position in sterna recumbency with head/nose down
what are 5 goals of peri-operative fluid therapy? when studying, also be familiar with distribution of body water slides!
- correction of pre-existing abnormalities
- correction of normal on-going and surgically induced losses
- support of cardiovascular function
- counter negative physiologic effects associated with anesthetic drugs
- maintenance of a patent intravenous catheter
describe the types of fluid used under anesthesia (3)
- replacement solutions (isotonic):
-LRS, plasmalyte A, 0.9% saline - hypertonic saline: resuscitation measures
-7.5% NaCl, 23.4% NaCl - colloids:
-hetastarch, vetstarch, albumin, etc.
describe isotonic replacement solutions
- most common fluid type used in anesthesia
- isotonic formulations containing electrolytes and buffers such as lactate and acetate
- high sodium concentrations close to ECF
- used for replacement of existing and ongoing losses
- advantages: low cost, low viscosity, vehicle for many fluid additives and drugs
describe hypertonic saline
- use:
-rapid resuscitation of patients in shock
-treatment of elevated intracranial pressure - 100mL of hypertonic expands plasma volume by up to 400mL (1:4 return); bolus effect only lasts for 20-30 minutes
- dose: 4-6ml/kg for dogs or 4ml/kg for cats, administered for over 5 minutes
- pulls volume from interstitial fluid
describe colloids
- cause an increase in colloid osmotic pressure which pulls fluid into the vasculature, expanding circulating volumne
- most useful in patients that are already hypoalbuminemic
- natural colloids: products containing albumin: whole blood, plasma, canine albumin
- synthetic: hydroxyethyl starches- modified polymers of amylopectin
-in patients under general anesthesia; generally administered as a single bolus of 3-5ml/kg IV
-adverse effects:
–altered coagulation, renal injury
–recommended to avoid in septic patient
current recommendation:
-do not exceed 20 ml/kg/day in dogs and 10ml/kg/day in cats
describe methods of fluid administration
- IV:
-most common
-simple, minimal adverse effects - intraosseous:
-often necessary in tiny patients when venous access unavailable
-complications: pain, potential fracture of bone, often fall out - subcutaneous:
-not commonly used peri-anesthetically
-less effective for rapid resuscitation
-fluid must be absorbed from interstitial space
what is the current IV fluid rate for healthy patients under anesthesia?
dogs: 5ml/kg/hour
cats: 3
rate should be adjusted to account based on patient needs (existing dehydration, cardiovascular disease, renal disease)
what is the current shock dose of fluids”
based on patient’s blood volume
dogs: 90ml/kg
cats: 55ml/kg
used in patients in need of rapid volume resuscitation: give 1/4 then reassess and repeat
