Test 4: PACU (pt 3/3) Hypothermia, PONV Flashcards
What is the definition of hypothermia?
A condition marked by an abnormally low internal body temperature (below 36°C), that occurs when systemic heat loss exceeds heat production.
The greatest amount of heat loss occurs during the _____ hour in the periop setting, and patients in rooms at a temperature of ____ degrees C will all develop hypothermia.
Reports suggest that the greatest amount of heat loss occurs during the first hour in the perioperative setting and that patients in rooms at a temperature of 21°C will all develop hypothermia.
What are the 4 Mechanisms for heat loss?
Radiation
Evaporation
Convection
Conduction
What is the mechanism responsible for the majority of heat loss?
Radiation
What is Radiation Heat Loss?
The loss of heat from a warm or hot surface (the body) to a cooler one (the environment).
-It does not require that the two surfaces be in direct contact with each other.
-Accounts for 40% to 60% of heat loss to the environment.
-Especially profound in the elderly, debilitated, and neonatal populations.
What is Convection Heat Loss?
-2nd most important contributor
-Convective heat loss depends on the existence of a temperature gradient between the body and the ambient air.
-This type of heat loss may occur in the OR, particularly in laminar flow rooms, and accounts for 25% to 50% of heat loss.
What is Conductive Heat Loss?
Loss of heat from a warm surface that comes into contact with a cooler one; it accounts for as much as 10% of heat loss in the OR, where patients lose heat to cooler OR tables, sheets, drapes, skin preparation fluids, and IV fluids or irrigants.
What is Evaporative Heat Loss?
Transfer of heat during the change from a liquid to a gas. Evaporative heat loss occurs via perspiration, respiration, or exposed viscera during surgery. Evaporation accounts for as much as 25% of heat loss in the OR.
What are other surgical related factors that cause hypothermia?
-Ambient room temperature
-Redistribution of lower-temp blood from the vasodilated, anesthetized periphery to the central compartment also accounts for significant heat loss.
-General and regional anesthesia inhibit thermoregulation and cause significant vasodilation such that temperature monitoring is warranted.
-Opioids and muscle relaxants depress shivering
-Any patient in whom a body cavity is entered will lose heat via convection/evaporation
-Irrigation solutions are cold
-During local anesthesia or sedation, temperature monitoring should be considered under circumstances in which the patient is at risk of hypothermia and should always be immediately available.
General anesthetics depress the _______________ center, with a usual temperature drop of ___°C to ____°C.
General anesthetics depress the thermoregulatory center, with a usual temperature drop of 1°C to 3°C.
Warming ____ induction can reduce redistribution hypothermia.
BEFORE induction
What are the physiologic consequences of Hypothermia?
-Increased O2 consumption 400-500% through shivering
-Increased risk CV events, MI, and sickling with sickle cell dz
-Impaired coagulation and cold-induced defect in platelet function (Increases surgical blood loss → increased transfusion rates)
-Decreased drug metabolism and elimination
-CNS depression
-Discomfort and decreased patient satisfaction
-Impaired wound healing, surgical site infection
-Prolonged PACU stay and increased hospital costs
____ of hypothermia is far superior to ______________________!!!
Prevention far superior to active rewarming!!!
What are strategies for Hypothermia Prevention?
-Assess every patient of the need for prewarming in preop
-Preoperative cutaneous warming: forced air warming blanket
-Airway heating and humidification (HME): More effective in pediatrics
-Warm IV fluids and fluid warmers (1U PRBC or 1 L crystalloid can decrease temp by 0.25oC )
-Warm ambient OR temperature (> 23oC required to maintain normothermia)
-Cutaneous heating: warm blankets, forced air warming systems
Postoperative nausea and vomiting (PONV) affects ___% to ___% of all surgical patients, and the chance for PONV can be as high as ___ to ___% for high-risk patients.
Postoperative nausea and vomiting (PONV) affects 20% to 30% of all surgical patients, and the chance for PONV can be as high as 70% to 80% for high-risk patients.
What are the patient-related factors that increase risk for PONV?
-Female gender
-Non-smoker
-Hx PONV/Motion sickness
-Childhood after infancy and younger adulthood
Possible factors:
-PS 1 or 2
-Hx of migraines
-Preop anxiety
-Hx of PONV in 1st degree relative
What are the surgery-related factors that increase risk for PONV?
-Increased duration of surgery (>3 hrs)
-Dehydration (ensure adequate hydration)
Possible factors:
-Type of surgery (Intra-abd, hernia repair, laparoscopic, gyn, ENT (strabismus), orthopedic)
-NPO status
What are the anesthesia-related factors that increase risk for PONV?
-Use of Volatile anesthetics/ N2O
-Use of intra and postop opioids
Possible factors:
-Increased duration (>3 hrs)
-Use of GA
-Use of longer acting opioids (morphine)
-Use of Neostigmine for reversal (>2.5 mg)
1-2 risk factors is what risk for PONV? How do you prevent it?
Moderate-to-severe risk
-Prevention with 2 to 3 drugs from different classes
3-4 risk factors is what risk for PONV? How do you prevent it?
Severe risk
-Consider avoiding GA or use a propofol-based anesthetic
-Minimize opioids (5)
-Prevention with 3 drugs from different classes
What should you do if you cannot avoid GA?
-Use TIVA with propofol and opioid adjuncts
-Opioid sparing techniques
-Encourage preop oral intake of clear fluids
What medications are utilized in PONV Prophylaxis?
-Ondansetron (5HT3 antagonist)
-Metoclopramide (D2 Antagonist in the CTZ)
-Droperidol (D2 Antagonist) - caution with sedation effects up to 12 hrs
-Dexamethasone (suppresses GI peritubular inflammation)
-Scopolamine transdermal (Anti-muscarinic: most useful with motion sickness)
-Pregabalin (reduces need for opioids)
What are the intended and adverse effects of Scopolamine?
-Acetylcholine muscarinic antagonist
-Crosses the BBB
-Long acting effects (up to 72 hrs): good for PDNV
Adverse effects:
-Sedation
-Dry mouth
-Blurry vision
-Confusion
-Central cholinergic syndrome
-Mydriasis and cycloplegia
-Can worsen narrow-angle glaucoma
What are the goals of fluid management during the perioperative period?
To maintain adequate intravascular fluid volume, left ventricular filling pressure, cardiac output, systemic blood pressure, and oxygen delivery to tissues.
-Appropriate concentrations of body fluid and electrolytes in the perioperative patient is essential to normal physiologic function of all body systems.
What are the symptoms of hypovolemia?
-UO can be misleading
-Poor skin perfusion (cool, pale, and clammy skin, particularly in the feet)
-oliguria
-hypotension
-tachycardia
-tachypnea
What causes hypovolemia in the periop period?
-Failure to replace preoperative fluid deficit and fluid or blood lost during surgery
-Ongoing hemorrhage, sweating, and exudation of fluid into tissues (i.e., third-space losses) in the PACU
-Occult blood loss (RP bleeding)
-Diffuse oozing r/t coagulopathy
-Hemorrhage into muscle after trauma or orthopedic procedures
T/F: Hypothermia can mask low intravascular volume.
True; In a hypothermic, vasoconstricted patient, a low intravascular volume might maintain cardiac output on PACU admission but cause hypotension when venous capacity increases during rewarming.
What is the leading cause of AKI in hospitalized patients?
Surgery
What are triggers of tubular dysfunction?
-hypotension
-hypovolemia
-cardiac dysfunction
-nephrotoxins (meds and contrast dye)
-tissue edema
-fluid overload
-abdominal hypertension
-microvascular dysfunction
-inflammatory-mediated sepsis
What are patient risk factors for AKI and Oliguria (<0.5 mL/kg/hr)?
-CKD
-obesity/metabolic syndrome
-DM
-CV dz
-hepatobiliary dz
-anemia
-Foley catheter functioning?
What provides the greatest protective benefit for kidney function?
Maintaining mean arterial pressure within renal autoregulation and administration of appropriate fluid therapy provide the greatest protective benefit.
What are the Renal Protective Strategies?
1) Correct anemia and minimize blood transfusions
2) Maintain perfusion MAP 80-160mmHg (Autoregulation)
3) Avoid nephrotoxins (aminoglycosides, vanco, contrast)
-If contrast is needed, give N-acetylcysteine and Sodium Bicarb for protection
4) Use balanced crystalloid solutions
-Avoid 0.9% NaCl and HES solutions
5) Avoid diuretics: furosemide and mannitol
6) Continue statin therapy
7) Maintain normoglycemia
8) Consider low-dose dexmedetomidine and sodium bicarbonate infusions
9) Dexamethasone (protective effect)
10) Early initiation renal replacement therapy
What meds do you hold preop to prevent AKI?
-ACEIs
-ARBs
-NSAIDs
-Diuretics
What do PACU orders typically include?
-Vital signs & parameters
-Respiratory support (NC, CPAP, nebulizers)
-Fluids
-Analgesics, anxiolytics, antiemetics
-Other PRN medications: antihypertensives, respiratory, insulin
-Laboratory and diagnostic tests (CXR)
-Discharge criteria
What is the most commonly used PACU discharge assessment score? What criteria does it use and what is the discharge criteria score?
Aldrete;
LOC, Activity, Circulation, Respiratory effort, and Oxygenation
-Discharge criteria is 9-10
