MH, PONV, temp control Flashcards
1
Q
Postoperative Nausea and Vomiting (PONV)
A
Nausea, retching, or vomiting
In PACU & w/in 24H postop
2
Q
Post discharge nausea and vomiting (PDNV)
A
Symptoms that occur after discharge for outpatient procedures
3
Q
_______ is a frequent cause of “unexpected hospital admission” after ambulatory surgery
A
Prolonged vomiting
4
Q
T/F
Patients often rate PONV as worse than postoperative pain
A
True
5
Q
POV affects __ % of all surgical patients.
The incidence of nausea is __%.
PONV in high-risk patients can be up to __%.
A
30
50
80
6
Q
High Risk of PONV in Adults
A
Female
History of PONV or motion sickness
Nonsmokers
Younger
Type of surgery
Opioid analgesia
7
Q
T/F
PONV can delay PACU discharge
A
True
8
Q
Risk Score of PONV in Adults
(Apfel Simplified Risk Score)
A
2+ points = high risk
9
Q
Postdischarge Nausea and Vomiting (PDNV)
risk factors
A
Female Gender
History of PONV
Age <50
Use of opioids in PACU
Nausea in PACU
10
Q
Risk Score For PDNV in Adults
A
11
Q
PONV
Potential Consequences
A
Increased cost
Increased admission rates (ambulatory care)
Suture dehiscence
Aspiration
Increased ICP
Pneumothorax
Patient Dissatisfaction
12
Q
Factors that increase PONV
A
Hypercarbia, Gastric insufflation
Sympathetic stimulation
Methohexital
neostigmine?
Etomidate
Volatile anesthetics (↑ 2-3%)
(Limited to early postoperative period (30-60 mins))
Nitrous
Opioids
HypoTN, Dehydration, Fasting
Duration of anesthesia
Anesthetic technique
Experience of the anesthetist
Placement of airways
13
Q
PONV
Surgeries that can increase risk
A
Cholecystectomy
Gynecologic (GYN)
Laparoscopic Procedures
Eye and Ear surgery
Shoulder?
In Children:
Strabismus surgery
Adenotonsillectomy
Inguinal, scrotal or penile procedures
14
Q
On Apfel scoring, what is considered high and low risk?
A
15
Q
Pediatric APFEL Score
A
0= 10%
1= 10%
2= 30%
3= 50%
4= 70%
16
Q
Pathophysiology of PONV includes ____ & ____ mechanisms.
A
Central and Peripheral mechanisms
17
Q
Five principal neurotransmitter receptors
A
-Anticholinergic/Muscarinic M1
-Dopamine D2
-Histamine H1
-5-hydroxytryptamine (5HT-3) serotonin
-Neurokinin 1 (NK1) or Substance P
All may be targets for prevention or treatment
18
Q
Chemoreceptor Zone (CTZ)
A
4th ventricle in the area postrema
Dopamine D2 and 5HT-3
Susceptible to drugs and toxins (Chemo), anesthetic agents, opioids
19
Q
T/F
The CTZ is protected by the blood brain barrier
A
False
not protected
20
Q
Vestibular System
A
Histamine H1 and Muscarinic M1
Motion and equilibrium, middle ear
21
Q
Vomiting Center
A
in nucleus tractus solitarius in postrema and lower pons
22
Q
Physiologic Areas involved
A
Chemoreceptor Zone (CTZ)
Vestibular System
Vomiting Center
Cerebral cortex
GI tract
23
Q
GIT features involved in N/V
A
-Afferent vagus nerve
-Enterochromaffin cells release serotonin
24
Q
Strategies to Reduce Baseline Risk
A
-Avoid GA & use regional instead(A1)
-Adequate hydration(A1)
-Sugammadex instead of neostigmine (A1)
-Avoid nitrous in surgeries lasting over 1h (A1)
-Use propofol for induction & maintenance(A1)
-Avoid volatiles (A2)
-Minimize intraop (A2) & postop opioids (A1)
25
Opioid sparing/Postop pain control (ERAS)
Celebrex and Neurontin, Tylenol (IV or PO)
NSAIDS
Ketamine
Precedex
**Robaxin**
26
T/F
Avoiding hypertension will help prevent N/V.
False
avoid hypotension
27
Instead of GA, use....
regional
TIVA
28
T/F
Supplemental O2 concentration can help prevent PONV.
True
29
PONV
Treatment/ Pretreatment
Scopolamine patch
Reglan
Decadron
Zofran
Propofol
Vistaril (Histamine 1)/Ephedrine 25/25 mg IM
30
Scopolamine patch
MoA
When to apply
When to remove
(competitive inhibitor at muscarinic sites)
2 hours prior to induction of anesthesia and remove 24 hours after use
31
Reglan MoA
Dopamine 2 antagonist
32
Decadron dosing
4-8 mg on induction (steroid)
33
Zofran
dose
MoA
4 mg at the end of surgery
(5-HT3 receptor antagonist)
34
used to treat Chemo-induced N/V (CINV)
Neurokinin 1/Substance P antagonists
Aprepitant PO (half-life of 40 hours)
Fosaprepitant IV
Rolapitant PO/IV (half life of 180 hours)
35
Phenergan (phenothiazine)
36
Butyrophenones for N/V
Droperidol
Haldol
37
(Effects of Opioids on N/V)
Incidence of PONV is greater than __% following balanced anesthesia
50
38
Opioids cause PONV by their effects on
the chemoreceptor zone (CTZ) in the area of the postrema of the brainstem
39
(Opioids)
Moving the patient (transport to the PACU) can exacerbate N/V d/t...
increased sensitivity of the vestibular system
40
CTZ receptors
**dopamine (D2)
serotonin (5HT3)**
histamine
opioid
muscarinic acetylcholine
41
these structures send neural projections to the vomiting center in the medulla
CTZ, vagal nerve, and vestibular organs
42
CTZ & vomiting center
location
CTZ: 4th ventricle of postrema (brainstem)
vomiting center: medulla
43
Opioid-Free Anesthesia
components
-**Exparel (liposomal bupivacaine)**
-**Magnesium**, Lidocaine IV
-Ketamine drip
-Propofol drip
-Antiemetics
-NSAID, Tylenol, Gabapentin, Celebrex
44
Enhanced Recovery After Surgery (ERAS)
components
**-No NG tube!
-Carbohydrate rich clear drink
-Regional Anesthesia/Transabdominal Blocks (TAP block)**
-TIVA
-Ketamine, Precedex, Lidocaine, Magnesium
-Gabapentin, Celebrex, Robaxin
-IV/PO Tylenol
-NSAIDs
-**Exparel (liposomal bupivacaine)**
45
Thermoregulation
3 phase process
Afferent thermal sensing
Central regulation or control
Efferent responses
46
Autonomic responses to heat & what mediates it?
sweating and active cutaneous vasodilation
**sweating is mediated by postganglionic cholinergic nerves**
47
Autonomic response to cold:
-Cutaneous vasoconstriction
(alpha-1 adrenergic receptors)
-Synergistically augmented by hypothermia-induced alpha-1 and 2 receptors
48
4 mechanisms of Heat Loss
Radiation
Conduction
Evaporation
Convection
49
#1 & #2 source for heat loss
#1: radiation
#2: convection
50
Radiation
Dissipation of heat to cooler surroundings
greatest heat loss (between 40-60%)
Depends on cutaneous blood flow & exposed surface area
Head
51
Convection
**Airflow** over exposed surfaces
Accounts for about 15-30% of intraoperative heat loss
52
Evaporation
Heat loss thru conversion of water → gas (body perspires)
8-10% of heat loss during surgery
Major open wound surgery
53
Conduction
Heat loss through physical contact with another object (cold surface; bed, mattress)
5% heat loss
54
Mechanisms of heat loss
%'s of heat loss
Radiation 40-60%
Convection 15-30%
Evaporation 8-10%
Conduction 5%
55
Hypothermia consequences
Wound infection & delayed healing
↑ O2 consumption (shivering)
↑ risk CV incidents (3x incidence of VT & cardiac events)
↑ sickling (sickle cell pts)
↓ platelet function
impairs coagulation cascade activation
(coagulopathy is the most well-studied complication of hypothermia)
56
Patients at high risk for hypothermia
Elderly: less subQ fat & altered hypothalamic fxn
Neonates
Intoxication: vasodilation & depressed heat regulatory center
Female
57
Certain drugs that cause alterations in thermoregulation
vasodilators, NSAIDs and phenothiazines
58
Neonates
-immature thermoreg center
-**high surface area: body mass**
-absent response to shivering (nonshivering thermogenesis)
59
If temperature falls from 37 to 35 by how much does the risk of infection increase?
2-3 times
60
How does hypothermia increase infxn risk?
Vasoconstriction
↓
Decreased blood & O2 delivery to the wound
**Decreased superoxide production**
60
If intraop temp falls to ___ degrees will increase the hospital stay by 2.5 days
35
61
Perioperative period and Hypothermia
General anesthesia:
Peripheral vasodilation
altered thermoregulation
inability to generate heat by shivering
62
(Neuraxial anesthesia)
Perioperative period and Hypothermia
d/t:
sympathetic blockade
muscle relaxation
lack of afferent sensory input → central thermoregulatory centers
63
Perioperative period and Hypothermia
OR practices
Cold fluids and blood, prep solutions, exposure
64
⭐️
fall in temperature during GA
3 phases:
1) initial rapid decrease **~0.5 - 1.5°C in ~30 min**
2) slow linear reduction of about 0.3°C per hour
3) plateau phase as shown
65
Chapter 13 in Anesthesia equipment read and understand how anesthesia affects the body
🤨😒
66
Redistribution
-Internal distribution of body heat after GA induction
-Hypothermia after **SAB or Epidural** induction = added redistribution to **legs**
67
If the temperature falls from 37 to 35.5, what is the average increase in estimated blood loss (EBL)?
~500 cc
Decreased activity of clotting factors
68
T/F
Coag panels will show hypothermia induced coagulopathy
False
Labs run at inconsistent temps
you wont see hypothermia-induced coagulopathy on your coag panel
TEG (tests the strength of the clot) is usually warmed, but not mandatory
69
Why is hypothermia BAD for the heart?
(As pt rewarms after surgery)
Shivering
Arrhythmias
Hypertension
Tachycardia
(note: hypothermia causes hypoTN and brady<3 but we're talking about going from cold to warm in this instance)
70
Compared to temperature of 35 degrees, normothermia is associated with a reduction in cardiac morbidity by ___%
55
71
Hypothermia and the ECG
mild & moderate
Mild hypothermia: sinus brady
Moderate hypothermia: prolonged PR, widened QRS, prolonged QT
72
Hypothermia and the ECG
severe
(below 32 degrees)
**hypothermic hump/J-wave (Osborne)**
elevation at the junction of the QRS and ST segments
73
⭐️
MAC is decreased ___% per degree C decrease in core body temperature
5-7%
hypothermia DECREASES MAC
74
Hypothermia
liver and renal fx
↓ renal blood flow and clearance
↓ hepatic blood flow can decrease metabolism
75
Hypothermia (decreases/increases) Protein binding
increases
76
Hypothermia & NMBs
Prolongs muscle relaxants
77
These drugs can depress voluntary shivering that generates heat
Opioids and muscle relaxants
78
During the first hour after induction of anesthesia, core body temperature can drop by 1.5° C due to what?
redistribution of body heat from core to periphery
79
What is the definition of hypothermia?
core temp 36 C or less **within 1H of start of case**
80
Which of the following is not an adverse effect of intraoperative hypothermia?
Increased risk of DVT/PE
Hypertension and tachycardia
81
Peds
methods of heat loss %'s
Radiation 39%
Convection 34%
Evaporation 24%
Conduction 3%
(note: same order from greatest to least as adults; just diff %'s)
82
Room temperature should be increased to at least ___℃ before *nonfebrile* neonates and infants arrive
26
83
The 4 heat loss mechanisms
84
How can we prevent or decrease the drop in patient temperature from redistribution after induction?
Increasing mean body temp
via
Pre-warming
usually need 30 min to be effective
(60 mins for large spinal surgeries)
85
⭐️
most effective non-invasive method of warming a patient?
Forced air warming blanket
86
⭐️
overall most effective method for warming a patient (invasive and noninvasive)?
Cardiopulmonary bypass
87
Pre-warming
-prevent/decrease drop in temp from redistribution after induction
-Increases mean body temp
-30 min to be effective
(60 mins for large spinal surgeries)
88
Where is the most accurate place to measure body temperature (closest to what the hypothalamus sees)?
Distal esophagus
45 cm from nose
89
Temperature Monitoring
Sites
🏆 Pulmonary artery (PA)
Distal Esophageal
Skin
Nasopharynx
Rectal
Bladder
External auditory canal
90
Distal Esophageal Temp monitor
optimal position
45cm from the nose
91
Hyperthermia
definition
⬆️ body temp 2C/hr
-or-
Core > 38C
92
Hyperthermia vs Hypothermia
which is uncommon in the OR?
hyperthermia
93
⭐️
Hyperthermia
Usual causes
sepsis or **overheating due to active warming**
other causes:
Malignant Hyperthermia (MH) or other syndromes
94
Manifestations of Hyperthermia
Increased metabolic requirements
Increased O2 consumption
**Increased minute ventilation**
Sweating and vasodilation
Tachycardia
95
Conditions associated with Hyperthermia
MH and Neuroleptic Malignant Syndrome
Pheochromocytosis, sepsis
Transfusion reaction
Serotonin syndrome
96
Malignant Hyperthermia
Inherited clinical syndrome
characterized by:
elevated **core** temperature
tachycardia
tachypnea
hypercarbia
muscle rigidity
rhabdomyolysis
acidosis
hyperkalemia
97
⭐️
Malignant Hyperthermia
Underlying abnormality relates to
uncontrolled release of intracellular calcium from the sarcoplasmic reticulum
98
Those susceptible to MH have a mutation of the _________ that allows ________ of calcium from SR
ryanodine receptor
uncontrolled release
99
Malignant Hyperthermia
Leads to activation of:
muscle contractile elements
hypermetabolism
100
MH
Mode of Inheritance
70% + of MH cases are linked to RYR1
(on chromosome 19)
The channel is the RYR1 because it binds to plant alkaloid ryanodine
MH is an inherited in an autosomal dominant manner
Does NOT skip generations
101
RYR1
calcium channel in the membrane of the sarcoplasmic reticulum of skeletal muscle
MH = defective
102
Why is it called the RYR1 receptor?
it binds to plant alkaloid ryanodine
103
⭐️
T/F
MH can skip a generation
FALSE
104
MH
Pathophysiology
abnormal/uncontrolled elevation of intracellular calcium levels in skeletal muscle
RYR1 calcium channel locked open
↓
uncontrolled Ca release (ICF Ca high)
↓
Continuous muscle activation
↓
ATP breakdown (even more heat production)
↓
SR Ca pump unable to reuptake Ca
105
Family History significance in MH
Any Family history
**especially** first-degree relative
106
MH
Associated skeletal muscle diseases:
Central core disease
King-Denborough syndrome
Multiminicore disease
Centronuclear myopathy
Congenital fiber-type disproportion
Native American myopathy
107
MH
Specific Clinical Features
Uncontrolled, exaggerated, hypermetabolic state triggered by inhaled anesthetics and/or succinylcholine
Unexplained ↑ETCO2 during constant ventilation
Generalized & Masseter rigidity
↑ T (rarely >40 degrees C)
108
MH
most sensitive and specific sign
Unexplained Increase in end-tidal carbon dioxide during constant ventilation
109
Generalized rigidity vs Masseter muscle rigidity
which is more specific?
Generalized rigidity (HIGH specificity)
Masseter rigidity (not as specific)
110
MH
Non-Specific Clinical Features
Tachycardia (earliest & most consistent sign, but not specific)
Tachypnea
Arrhythmias
Skin Mottling
Profuse sweating
Altered blood pressure
111
Tachycardia as a sign in MH
earliest and most consistent sign, although not specific
112
MH
Hyperkalemic Cardiac Arrest
Sudden hyperkalemic cardiac arrest after MH triggering agents in children with undiagnosed myopathy
especially dystrophinopathies, Duchenne or Becker's muscular dystrophy
113
T/F
Hyperkalemic Cardiac Arrest is a result of pathophysiologic changes typical of MH
False
not a result of this
114
MH
Hyperkalemic Cardiac Arrest is r/t...
muscle membrane destruction leading to hyperkalemia
115
MH
Hyperkalemic Cardiac Arrest
Treatment
Treatment for hyperkalemia
116
Lab Findings of Acute MH
117
MH
Preop Evaluation
Detailed medical history:
Previous surgery and issues
Family history
History of **heat stroke or exaggerated reactions to heat and exercise**
118
MH
Preparing the anesthesia machine
1) Disable/remove/cover vaporizers
2) new breathing circuit & reservoir to y-piece of circle system
3) inflate (10L/min of fresh gas for up to 60-90 min; older machines 10L/min FGF for 20 min)
4) Change the CO2 absorbent
5) Activated charcoal filters to both limbs of the anesthesia breathing circuit before and during the procedure to reduce **vapor [ ] to <5 ppm (increases washout period)**
119
MH
Med cart preparation
Cover/Tape the succinylcholine or remove it
120
How does Dantrolene/Ryanodex work?
Direct-acting skeletal muscle relaxant
**hydantoin derivative (anticonvulsant – Dilantin derivative)**
Directly interferes w/ contraction
-**inhibits Ca release** from SR
? binds to the RYR1r
121
Dantrolene/Ryanodex
temp control
Can lower temp in
-neuroleptic malignant syndrome
-thyroid storm
122
MH Algorithm
123
Most accurate diagnostic for MH
exposure of biopsied skeletal muscle to halothane, caffeine, and ryanodine
124
MH
skeletal biopsy testing
-Thigh biopsy
-suspended in awater bath at 37C
-exposed to halothane, caffeine, or ryanodine
diagnosis of MH is based on:
Isometric contracture measured w/ strain gauge
(threshold & height of contracture)
125
MH
muscle biopsy test statistics
highly sensitive and close to 100%
20% of positive results are false-positives
126
Neuroleptic Malignant Syndrome
Signs/Symptoms
Muscle Rigidity and rhabdomyolysis, acidosis and tachycardia
Increased temperature
Depressed consciousness
Autonomic instability
127
⭐️
Neuroleptic Malignant Syndrome
Underlying pathophysiology
R/t **central dopaminergic blockade at hypothalamus**
128
Neuroleptic Malignant Syndrome
Triggers:
neuroleptics (Haldol)
antidopinergics
phenothiazines
other centrally acting drugs (Compazine, Reglan, Droperidol, and Phenergan)
129
Neuroleptic Malignant Syndrome
Treatment
Benzodiazepines
Dopamine agonist (**bromocriptine**)
May respond symptomatically to dantrolene
130
Serotonin Syndrome/Toxicity
excess serotonin in the CNS
131
Serotonin Syndrome/Toxicity
S/S
Mental status changes
Autonomic hyperactivity (fever, tachy🩷, HTN, diaphoresis)
Neuromuscular abnormalities (tremor, **hyperreflexia**)
132
Serotonin Syndrome/Toxicity
r/t pts on...
SSRIs, **MAOI**, tricyclics, amphetamines, **Demerol**
methylene blue
(acts as MAOI; increases serotonin levels, can be a trigger for serotonin syndrome)
133
Serotonin Syndrome/Toxicity
Treatment
Active cooling
IV fluids
↑ anesthetic depth to ↓ autonomic hyperactivity
Serotonin antagonist
(Chloropromazine IV, Cyproheptadine PO)
134
T/F
Avoid antipyretics in Serotonin Syndrome/Toxicity
True
Antipyretics have no role in this syndrome and should be avoided
Use NMB to help reduce rising body temperature
135
Drugs that can Increase risk for Hyperthermia
↑ basal metab rate & heat production:
-Sympathomimetic drugs
-Monoamine oxidase inhibitors
-Cocaine
-Amphetamines
-Tricyclic antidepressants
↑ T by suppressing sweating:
-Anticholinergics
-Antihistamines
136
How to treat Hyperthermia
Expose skin surfaces
Cooling blankets
Ice packs
Cool fluids
Antipyretics
Treat the cause
TURN OFF THE BAIR HUGGER
137
Dantrium/Revonto vs Ryanodex
