PoA1 Flashcards
1
Q
Where does hypobaric solutions gravitate toward?
A
C3 (phrenic nerve) and L3, the high points when a patient is supine
2
Q
What arteries supply the cord? Where do they originate
A
Anterior Spinal Artery (from vertebral artery 75%), 2 Posterior Spinal Arteries (25%), and segmental spinal arteries
3
Q
Dura Mater origin and endpoint
A
Foramen magnum and to the end of Dural Sac S2
4
Q
CSF Factors
A
150ml total
decreased CSF amount means increased LA spread and to use a lower amount
Common causes are low weight increased abdominal pressure
5
Q
Thumb Dermatome
A
C6
6
Q
Spinal Considerations: Lidocaine
A
It’s pretty short acting, used for outpatient
7
Q
Which spinal is goated for duration
A
Bupivacaine (0.75% in 0.5% dextrose)
8
Q
Morphine Neuraxial Adjunct key points
A
Water soluble hydrophilic and will lead to delayed respiratory depression from slow spread in CSF
9
Q
Opioid Neuraxial side effect and prevention
A
Pruritus use <300 mcg morphine, 50-75mcg it’s absent, give 4mg zofran or Nubain prophylactically
Respiratory Depression lipophilics will occur sooner (Fent and Sufent) later with hydrophilic agents (morphine)
They DO NOT prolong block, only enhance density
And urinary retention
10
Q
Alpha 2 Agonist Neuraxial Effect
A
Intensifies and Prolongs the block and analgesia (Dex, Clonidine)
11
Q
Differential Blockade
A
nerve fibers withing a nerve means we see a progression of block onset
B sympathetic fibers, then C & A delta fibers (i.e. slow pain,touch and temp are blocked second),
B-Sympathetic, then C and A delta (pain, temp, touch), followed by A Gamma (Motor tone/NOT SENSORY) then A Beta (touch, pressure) then A Alpha (motor and proprioception) Recovery is inverse so B Sympathetic fibers are blocked longest
12
Q
LA Drug/Controlable Factors affecting (Spinal) block height
A
Dose (increase dose, increase duration), baracity, site of injection, patient position
13
Q
LA Patient/Non Controlable Factors affecting Spinal block height
A
CSF volume, age, baracity, increased intra-abdominal pressure (fluffy or pregnant)
Greater Cephalad spread with greater age(greater neural nerve sensitivity), baracity(?) and less CSF
13
Q
Bezold-Jarisch Reflex
A
Protects LV when active, leads to bradycardia and hypotension
BJR is treated by Zofran as it’s mediated by 5HT3 receptors in vagus nerve
14
Q
Respiratory Response to Neuraxial
A
If high thoracic (T4) block, loss of Abdominal Muscle contribution in forced expiration-limits ability for active exhalation
15
Q
Thermo response to Neuraxial
A
shivering-Meperidine and Precedex and clonidine will treat it
16
Q
LAST/Failed Block get out of jail free card
A
1.5ml/kg 20% intralipid bolus for LAST, followed by 0.25ml/kg/min gtt
17
Q
Most probable LA anaphylaxis cause
A
PABA in Ester LA
18
Q
Block height for C-Section
A
T4
19
Q
Block for Knee Tourniquet
A
T10
20
Q
Needle Insertion Layer Path
A
Skin, subQ fat, supraspinous, interspinous, ligamentum flavum, dura mater, subdural space, arachnoid mater, subarachnoid space
21
Q
What spinal approach for metal rods or scoliosis
A
Paramedian-10-15 angle difference from midline
22
Q
“Total or High” Spinal
A
Unexpected cephalic spread of LA to high cervical/cranial nerves
caused by excessive dosing (and why you should check dermatomes frequently) or Rapid LA injection
23
Q
Postdural Punction Headache
A
Failure of dura puncture site to heal
Headache is when pt is upright
24
PDPH Treatment
**2-3 days after Headache when upright**
Supine bedrest, NSAIDs, Fent, Caffeine/Methylxanthine (vasoconstriction), **blood patch ~48 hours post onset**
*More likely with an Epidural as the gauge required is larger*
25
Cauda Equina Syndrome
L2-S5 coccygeal nerves are affected by LA procedure
**2/2 High dose 5% lido, Microcatheter use-causes lido to pool in cauda equina, and Small Whiticare 25/26 needle **
**IF DISC COMPRESSION, LAMINECTOMY IS NEEDED IN UNDER 6 HOURS
*symptoms range from back pain, saddle anesthesia, to ED, GU/GI dysfunction*
26
Auditory/Facial/Ocular Effects
**Horner's syndrome- ptosis, miosis, anhydrosis**
27
Epidural Pregger Concern
**Baston's plexus is engorged in the Lateral epidural space**
Dont inject into them, blood upon CSE entry means youre too **lateral**
**Be a Chad and inject inert fluid to open the epidural space prior to catheter insertion
*Blood in the catheter is also seen with multiple attempts, stiffer catheters or trauma to the epidural vein*
28
Why is 3% Chloroprocaine the fastest onset with a pK of 9?
**High 3% concentration leads to quicker onset, whats used in surgical anesthesia**
very short-duration is 45min and is an ester
29
What is the order of LA route onset greatest to least?
**IV, tracheal, intercostal, caudal, paracervical, epidural, brachial, sciatic, subQ**
I Told Immediately Chelsea Please Eat Big Scallop Subs
30
Epidural Dosing per segment
**1-2mL per segment**
give 5mls at a time to avoid High Spinal
31
Neuraxial Alkanlinization
**Speeds up onset, bicarb (1mEq/10ml) decreases [H+]/Increases nonionized drug**
*increases diffusion of drug AND speed of block onset*
32
Epidural Procedure Unique steps
Loss of Resistance with the air or saline
**Test dose with 3mL of 1.5% Lido + (1:200,000) Epi to see if IT or IV**
**uses 45mg Lido and 15mcg Epi**
*If HR jumps 20% or patient has metalic taste in mouth O O F*
*If dense motor block within 5 minutes occurs-you did a spinal essentially whomp whomp*
33
Positive Test Dose Signs
**Tinnitus, circumoral numbness, metallic taste**
33
34
Why are esters metabolized quickly
**Plasma Cholinesterases are how they are metabolized**
35
36
Patients allergic to Tetracaine, Benzocaine, and cocaine have cross reactivity to?
**PABA, and other Esters**
37
ANAA monitoring frequency standards
**BP, HR, and RR are q5 min**
*pulse ox is continous/mandatory, most do q3 min*
37
What is the SpO2 if PaO2 is 40mmHg
**75%**
at 60 mmHg it's 90
at 27 mmHg its 50
38
How is SaO2 estimated in pulse oximetry
**Pulsatility of Arterial Blood**
38
Carboxyhemoglobin Pulse Ox Concern? What is the % COHb in smokers?
**Falsely elevates SpO2**
**typically over 6%- they desat quickly and youll need to adjust accordingly**
Every 1% COHb increases, SpO2 increases 1%
*due to COHb absorbing light in the 660nm range as O2Hb does*
39
Pulse Ox Artifact Causes
**IV dyes (methelyne blue will cause it to drop), Venous pulsatility (clots/transpo of great vessels)**
*ambient light, low perfusion, nail polish, and other Hb forms will mess it up*
40
Korotkoff Sounds
Phase I: the most turbulent/audible (SBP)
Phase II: softer and longer sounds
**Phase III: crisper and louder sounds**
Phase IV: softer and muffled sounds
Phase V: sounds disappear (DBP)
41
Artline Waveform Periphery effect
**Steeper upstroke, higher systolic peak, later dicrotic notch, lower End-Diastolic Pressure**
Distal pulse amplification is from **impedance**
42
Square wave test
no more than two oscililations after fast flush and should get smaller
**to look for good resolution- System dynamic response**
43
Overdampening Waveform
absent dicrotic notch, lower sBP, narrowed PP with accurate MAP
**Less detail**
44
Pressure Waveform Analysis
identifies **residual preload reserve and fluid status**
*looks at cyclic artieral BP change from respiratory cycle with **PPVenting** and Lung voume change*
45
Positive Pressure Ventilation Effects on Pressure
Early Inspiratory phase- greater intrathoracic pressure, **increased total lung volume** - leads to **less LV afterload** and increased LV preload causing SV, CO, MAP to *increase*
Decreased venous return, increased PVR- leads to increased RV afterload **causing decreased RV SV**
46
Stroke Volume Variation
**Normal is 10-13%**
Computer calculates the stroke volume variation based on patient factors
*if greater than 10-13% GIVE FLUID-youll see SVV of 12%*
47
Pulse Pressure Variation
Max and min PP over the **entire respiratory cycle**
**Normal is LESS than 13-17%**
On the exam, if a patient is 13-17% **GIVE THEM FLUID, YOULL SEE 14% PPV ON EXAM, GIVE VOLUME**
48
Side-stream Gas Mixture Analysis
Most common, **Lag time causes longer rise time**
affected by tube diameter, length, sampling rate-bigger diameter, faster interpretation
*Gas must be brought to analyzer, most common*
49
Infrared Analysis/Absorption
**O2 doesnt absorb IR radation (no dipole)**
*measures CO2, N2O, H2O, and volatiles based on the asymmetry of molecules absorbing light at different lengths
measures energy absorbed of a IR band as it passes through a gas sample
50
What facial Nerve reflects laryngeal muscle block?
**Corrugator Supercilii is goated-reflects laryngeal adductor and abdominal muscles** better than the adductor pollicis
Ulnar Nerve is gold standard
51
Deep Non-depolarizing blockade
**Absent TOF, post tetanic stim present
Reversed with 4mg/kg Sugammadex**
Intense block- no response, 3-6 minutes after intubation dose of ND NMBD, reversal impossible unless 16 mg/kg sugamma
moderate- gradual return of 4 responses of TOF stimulation, neostimine reversal is good and sugammadex is 2mg/kg
52
Depolarizing Blockade Phase II
**Presence of post-tetanic facilitation**
53
How many channels does BIS use
**4, 2 per hemisphere**
54
What nerve picks up heat/warmth
**Unmyelinated C**
55
Hypothermia Complications
**Coagulopathy-reversible platlet aggregation**
**Decreased O2 delivered to tissues**
*wound healing will take longer*
**Decreased Drug metabolism-NMB can be prolonged**
*Gotta be hot to clot*
*increases transfusion need by 22%, blood loss by 16%
*post thermal discomfort is a thing*
55
What is the order of heat transfer greatest to least
**Radiation (40%), Convection (30%), Evaporation (10%), Conduction (ask a magic 8 Ball)**
56
Hypocarbia concerns
**decreases CBF (cerebral vasoconstriction), blunts respiratory drive,** decreases PVR, K goes extra to intracellular
ETCO2 of 28 mmHg, below is risky dingo
57
Bohr Equation
**measures deadspace to tidal volume**
58
Increased ETCO2 causes
is measured at the end of phase 3, **largest just before inspriation**
**Caused by:
increased metabolism(Fever/MH/sepsis/seizures)
Bicarb
Decreased alveolar ventilation-hypoventilation/NM dz/High spinal**
**Equipment issue-rebreathing, CO2 absorber spent, leak in circuit, or faulty inspiratory/expiratory valve**
59
Decreased ETCO2
**Hypothermia
Cardiac Arrest
Hypotension
Hemorrhage
PE
HYPERventilation or Pain**
**Equipment wise- vent disconnect, goose egg intubation, complete airway obstruction(laryngospasm), poor sampling-the breathing rate cant be too fast for the line to grab a sample, ETT cuff leak-room air will dilute the expired sample**
60
ETCO2 Phase 1
Respiratory baseline at 0, exhalation of anatomic deadspace/apparatus
**1/3 of tidal volume is exhaled**
**No CO2 should be present unless rebreathing**
61
ETCO2 Phase II Alpha Angle
110ish degrees- widened with expiratory airflow obstruction (COPD looks sharkfin, Bronchospasm, kinked ETT)
**Causes slanted Phase 2, separates phase 2 and 3**
62
Faulty Inspiratory Valve Effects
**Widened Beta Angle, decreased slope of inspiratory downstroke (phase 0)
Can cause Rebreathing when not going back to 0 baseline**
63
Cardiac Oscillations
**More common in Peds**, heart proximity to trachea causes this during inspiratory phase
*rapid heartrate causes timing of various lung fields to be different*
64
Re-breathing and Soda Lime exhaustion effect
**CO2 rebreathing/Inspiration and baseline increases**
*phase 0 doesnt change*
**This and faulty valve will be on the exam**
65
Curare Cleft
**NMB is wearing off**
Patient is spontaneously breathing during mechanical ventilation
**reparalyze or flip off the vent if its the end of the case**
66
Esophageal Intubation capnography
*Wounded Pride Intensifies*
spontaneous waveform then goes away, but if a tubes in it should be regular
if wave form has right ETCO2 peaks and regular rate then falls off, tube fell out or got kinked
67
What monitoring is continous in OR
BP and RR
68
What is my SpO2 if PaO2 is 40mmHg
75%
69
What causes slanted phase 2 in capnography
**Faulty equipment, rebreathing**
Phase 2 is the expiratory upstroke, CO2 Rich alveolar gas and is steep
70
What is the sensory portion of Oculocardiac Reflex?
**CN V (Trigeminal Nerve)**
71
Common cause of high spinal
**Too high of a dose
rapid administration
incorrect positioning
misplaced epidural catheter**
72
What is the mechanism of action of LAs
**Na channel blockade, specifically from inside**
73
What layer of the spinal column is responsible for the "Pop" during spinal/epidural
Penetration of the **Dura Mater**, entering the sub dura layer
74
Epidural Space Rostral, Caudal, Anterior, Posterior and Lateral borders
**Rostral/Caudal: Foramen magnum to near S5/Sacrococcygeal ligament
Lateral: Vertbral Pedicles
Anterior: Posterior Longitudinal Ligament
Posterior: Ligamentum Flavum and Vertebral Lamina**
75
Epidural Space Contents
Nerves, Fatty tissue, Lymphatics, Blood Vessels
*Fatty tissue can absorb and decrease bupivcaine availabilty compared to Fent/Lido/Morphine*
76
Plica Mediana Dorsalis
Lateral connective tissue band **in the Epidural Space** thought to cause epidural catheter placement issues and **unilateral blocks**
77
How many Cervical, Thoracic, Lumbar, Sacral, and Coccal nerves are there
Cervical 8
Thoracic 12
Lumbar 5
Sacral 5
Coccal 1
78
Where are Sensory information carried and Motor information carried?
**Anterior** Nerve Roots: **Motor and Autonomic information from cord to body**
**Posterior** Nerve Roots: **Sensory information from the body to the cord**
79
Umbilicus Dermatome Level
**T10 Sensory Level**
80
Are there spinal nerves innervating the face for sensory fields?
Nope, dat der CN5/Trigeminal nerve with the following branches:
V1-Opthalmic Nerve
V2-Maxillary Nerve
V3-Mandibular Nerve
81
Spinal/SAB/Intrathecal Block site of action
**Subarachnoid space of the cord, specifically the myelinated preganglionic fibers of the spinal nerve roots**
Also inhibits neural transmission in the **superficial layers of the cord**
82
Epidural site of action
In the epidural space outside the dura mater **diffuses through the dural cuff to reach nerve roots to work**
| *can leak thorugh the intervertebral foramen to the paravertebral space*
83
Factors NOT affecting Spinal/SAB spread
Barbotage
Speed of injection
Bevel orientation
Vasoconstriction (e.g. Epi or Phenylephrine)addition
Gender
**ALL DO NOT AFFECT SPREAD**
84
EPIDURAL Factors affecting spread and block height
Controlable with significant effect:
**LA volume
Level of injection
LA Dose**
Controllable with less effect:
**Local anesthetic concentration
Patient Position (has a significant effect but whatever)
Plica maybehaps**
85
Epidural **NON CONTROLABLE** factors affecting spread
Greater affect: **Pregnancy
Older age**
Meh effect: **Height(Taller may need 2 ml per segement, shorter lesser per)**
86
Epidural factors that **DO NOT** affect spread
Additives (though they do intensify or prolong block)
direction of needle bevel
injection speed
87
Differential Blockade Zones
Sensory level is **2 levels higher** than motor
Sympathetic level is **2-6 levels**
So a T8 block has T10 motor blocked below and T2-T6 Sympathetic block-will need Phenylephrine/Ephedrine as HR and BP will drop
88
Bromage Scale
PACU Motor Blockade monitoring scale 0-3
0-gucci, born to run
1-slight block cant raise extended leg
**2-moderate cant raise leg or move knee, CAN move feet**
**3-complete motor block cant move legs, knee, or feet**
89
CV Systemic effects of Neuraxials
Preload is decreased from sympathetomy and venous pooling
Afterload decreased from partial arterial dilation-SVR decreases 15% in healthy people and **25% in elderly/trash EF patients**
Cardiac Output is reduced from SV decreasing from the SVR/Venous Return effects
*Intially CO may rise from the vessel dilation* then proceeds to fall off a cliff
90
Reverse Bainbridge Reflex
Bradycardia triggered by *reduced stretching* of RA
91
Sudden Cardiac Arrest Cause and Incidence
Young adults with high parasympathetic unopposed from our acctions, occurs 20-60 minutes after
**7:10,000 spinals
1:10,000 epidurals**
92
Which drugs are indicated for hypotension with bradycardia secondary to SAB/Epidural? Hypotension solo?
Ephedrine dose, for bradycardia alone a dose phenylephrine/Neo
*Wait for your HR to change before cycling the cuff, otherwise it'll be another cattywampus read*
93
Prevention of Spinal induced Hypotension
Vasopressors like Phenylephrine
5-HT3 antagonist Zofran to counter BJR
Fluids we move away from preloading and **Co-load with 15mL/kg** 700-1Lish. Please dont tank someone with trash EFs by fluid overload. Or kidney injury with colloids and making the blood too viscous
Positioning slight pelvic tilting/Head up to prevent **Hyperbaric** solutions to tank your pressures further
Atropine for bradycardia alone, however tachycardia in someone with CAD is a bad time
94
Pulmonary Effects of Neuraxial
Minimal Impact, even with **T4**, only **ERV is decreased and by extension Vital Capacity**
95
Pickwickian Syndrome
BMI 40-50 when laid flat they panic as ERV and VC are low from baseline
*Reassure them and raise the HOB and get Semi Fowler Action going*
*putting on a nasal cannula will be a dice throw, some will be bothered more by it*
96
Diaphragm Innervation
C3, C4, C5
97
GI Sympathetic innervation
**T5-L2**
Sympathetic afferent-sends visceral pain
Sympathetic efferent-inhibits peristalsis, gastric secretion also causes sphincter contraction, and vasoconstriction
98
GI Parasympathetic
Afferent-sends saitey, distention, nasuea
Efferent-tonic contraction, sphincter relaxation, peristalsis, and secretion
99
GI Neuraxial Effect
Increases Parasympathetic and reduces Sympathetic tone
**Increases Peristalsis, 20% incidence of N/V
Reduces post op ileus in abdominal surgery**
100
GU Neuraxial Effects
RBF is stable if MAP is maintained
If you block above T10 urinary sphincter tone is relaxed
**addition of Neuraxial Opioids decreases detrusor contraction and Increases bladder Capacitance**
PACU will probably need a reminder to bladder scan
101
Neuraxial Metabolic Effect
Surgical stimulus elevates catecholeamines, cortisol, and RAAS
can partially suppress or totally block (in lower extremity cases) neuroendocrine response **if it's placed before surgical stimulus**
102
What determines the hydrophilicity of LA?
**Tertiary Amine, it is what accepts protons**
103
LA intermediate chain big deal
determines drug class and allergic potential *cough cough Esters and PABA cough cough*
104
Amide Metabolism
P450
105
Local Anesthetic Duration
How protein bound to A1-Glycoprotein
106
Factors Affecting Vascular Uptake and Plasma Concentration of LAs
Site of injection
Tissue blood flow
Physiochem properties
Metabolism
Vasoconstrictor addition
107
Which baracity of LA is good-er for hips
Isobaric, based on positioning and duration it stays put
108
Where do Hyperbaric solutions like to settle when patient is supine?
T6 and S2
109
Subarachnoid/Spinal dosing generally?
What would a T10 dose of 0.75% Bupivacaine be?
generally: are fixed, onset is 5 minutes, lastes 130-220 minutes
**15 mg, of .75% means 7.5mg per ml and so 2 mLs**
110
Epidural Dosing Concentrations
Very low concentrations-**Ropivicaine is 0.1-0.75%, Bupivacaine is 0.0625-0.5% as is Levobupivicaine**
111
Epidural Top Up dose
50-70% to be given **when sensory block segment drops 2 dermatomes**
112
Epidural: for a thoracic versus lumbar
**Lumbar space is dummy thicc so give 2 mls per segment, Thoracic is thinner so 1 will suffice as it'll spread more**
113
114
Epidural: Would a "walking epidural" be a lower or higher concentration? Why does it matter
lower concentration to achieve sensory block but spare motor
Concentration of LA in epidurals determines density/strength of block
115
Neuraxial Opioid Target
Substantia Gelatinosa of the dorsal horn (lamina 2)
Helps curb neurotransmission by decreasing cAMP, Ca2++ and increasing K++
116
Lipophilic Opioid adjuncts
Fent/Sufent have a shorter duration in CSF, and less spread
Onset is quicker, **but duration is shorter** so **respiratory depression occurs earlier**
117
Intrathecal Dose of Demerol/Meperidine? Epidural dose?
**Intrathecal: 10 mg**
**Epidural: 25-50mg**
Infusion rate is 10-60mg/hr
118
Intrathecal dose of Morphine? Epidural?
**Intrathecal: 0.25-0.30 mg**
**Epidural: 2-5mg**
infusion rate is 0.1-1 mg/hr
119
Neuraxial Alpha 2 Adjuncts and dose
Clonidine **15-45 mcg**
Precedex **3 mcg**
Intensifies and prolongs block, can cause bradycardia and hypotension
*off label use*
120
Neuraxial Vasoconstrictor adjuct dose and mechanism?
Epi 0.2-0.3 mg "epi wash"
Phenylephrine 2-5 mg
*Profoundly increases tetracaine duration*
121
Anticoagulation/Antiplatelet Neuraxial risk
Epidural hematoma, cord compression essentially
They'll get lower extremeity weakness numbness, low back pain, and GI/GU dysfunction
*whomp whomp if you DONT surgically decompress via laminectomy in 8 hours*
122
Aspirin and Montelukast mechanisms
Aspirin stops COX-1
**Risky if your stopping it in secondary use patient-means theyve already had a stroke**
Montelukast stops 5-LPO and helps asthmatics by curbing LTC4
123
Neuraxial guidelines for aspirin
High risk- oof and hold it 4-6 days *regardless of 81 or 325mg*
****Central doesn't require holding it****
124
NSAID Neuraxial precautions
For high risk procedures e.g. open aorta peripherial vascular **hold for 5 1/2 lives**
Central does not require any holding
125
Glycoprotein 2B/3A antagonist rec's for peripheral anesthesia
Hold Tirofiban and Eptifibatide **4-8 hours**
Abciximab **24-48**
126
Thienopyridine Derivative neuraxial guidlines
Clopidogrel **5-7 days**
Prasugrel **7-10**
Ticlopidine **10 days**
127
Unfractionated heparin rec's
Recall it puts factor 2/antithrombin on turbo, and inhibits **factors 2 and 10**
lower doses <5K units **4-6 hours**
Higher doeses ~20k units **12 hours**
therapeutic >20K or pregnant patient **hold 24 hours**
**If on it for over 4 days get a platelet count first prior to central neuraxial, hopefully it's over 100k**
128
LMWH (lovenox) heparin
*Prior to block* should be 12 hours since last dose for prophylactic
**delay for 24 hours if it's a bigboi therapeutic dose**
**Antifactor 10a in old farts/renal patients is a good idea**
129
Vitamin K Neuraxial Recs
*It impaires factors 2, 7, 9, 10*
Warfarin Hold for 5 days, make sure INR is gucci (<1.5)
130
Would you give regional/neuraxials after T-PA
Of course not. Absolute contraindication
Recall: thrombolytics activate plasminogen which bonk fibrin and break clots down
131
DOAC Rec's for Neuraxial
Eliquis, Bevyxxa (seriously?) Lixiana, Xarleto, Pradaxa all inhibit factor 10a
**D/C 72 hours before, look at anti-factor 10a if pressed**
132
Herbal Rec's for Neuraxial
behave similar to plasminogen, fine if patient isnt on any other blood thinners
133
Sphenopalatine Ganglion Block (SPG)
Soak or "pledge" a swab with LA (1-2% Lido or 0.5% Bupivacaine)
basically jam it in nostril toward the pack of the head, angled inline with the tragus line
**Works on the V2 divison of CN5**
134
Parethesia
*Fancy word for pain*
After a SAB/Epidural, patient has deficit near area of placement
associated with poor placement during needle advancement in Spinal/Epidural
Less likely with Epidural
More likely with CSE and not being midline
135
"Failed Spinal"
**No anesthesia**- You didnt stick the landing, if spinal is not active in the patient after 15-20 minutes try again
**Patchy block**- swallow pride and consider TIVA/GETA, repeat incurs neurotoxicity risk
**Unilateral Block**- adjust position, if that doesnt work TIVA/GETA is the play
136
GOAT antiseptic approach for neuraxial
*Neuraxial step 1: open kit
Neuraxial step 2: throw iodine in trash*
CHG + Alcohol pad
Dont be lazy, grab it ahead of time and wear gown, gloves, hat, the whole kit and kaboodle
137
Transient Neurologic Symptoms
Improper positioning stretching nerves, causing temporary myofacial strain/spasms
*typical s/s are radicular pain in the back and buttocks, onset within 6-36 hours of surgery. Lasts 1-7 days*
Caused (ish) by 5% lido, awkward positions like lithotomy (hip/knee flexion), and outpatient knee
**throw NSAIDS at them like candy and trigger point injections**
138
Retained Catheter Fragments
After epidural, remove introducer and catheter *together to avoid shearing*
139
Unilateral Epidural Block
Catheter was shot too far, exiting the epidural space or is smooshing a nerve
**pull cathere back 1-2 cm but ensure 3-5 cm still is in the epidural space**
**Also reposition patient to side that still isnt blocked i.e. left side down if their left side still is feeling it**
140
LAST
Common cause is inadvertent injection
usually seen with seizure, *if bupivacaine is the causitive agent cardiac arrest is seen first*
expect a spectrum of analgesia then circumoral numbness/tinnitus/hypotension and myocardial depression, then seizures, and finally coma/respiratory arrest with mounting plasma concentration
141
LAST systemic Risk/concerns
CNS: risk is higher with **hypercarbia**-higher cerebral perfusion higher LA drug deliver
**Hyperkalemia**-neurons are more excitable and
**metabolic acidosis**-lowers seizure threshold and increases brain drug retention via ion trapping
142
What *decreases* LAST risk
**Hypocarbia**
**Hypokalemia**
**CNS Depressants**
143
LAST Treatment
Manage airway-100% O2
Treat seizures- benzos **please dont crump cardiovascular system and avoid propofol**
Modified ACLS- give epi in low dose 1mcg/kg and amio for ventricular issues
Lipid emulsion- 20% lipid **100ml bolus, then 250ml over 15-20 minutes.** Repeat if still unstable
144
Arachnoiditis is associated with
LA with preservatives, and wipe off surgical prep off (especially if it's betadine)
Fever is the first sign in 1-3 days
*dont be a gilgamesh, make sure LA is farm fresh*
145
Why should you have a GETA set up for neuraxial
**Failed Spinal
High Spinal
LAST
Anaphylaxis
CV collapse
Case exceeds LA duration**
*Wrong dose, wrong location, or position are the causes*
146
146
Cutting Needles
That there be your Quincke and Pitkin and will likely be associated with PDPH
**Pencil point needles drag less shit and the "Pop" is more pronouced**
147
Spinal Steps
Timeout
Monitors (BP/SpO2)
Positioning (Mad Cat)
**ID/Mark SAB interspace**
Sterile prep with sponges
Drape
Draw meds with SAB filter
Wipe excess betadine off
localize with 1%
Instert spinal needle
**once crossing dura youll hear pop**
Withdraw stylet and watch for CSF
Rotate needle 360 (checks if youre in the right spot if CSF flow is weak-advance need a smidge more)
**Aspirate CSF with syringe of SAB LA to check for swirl (if it's hyperbaric)**
Inject SAB LA
Lay them flat quickly
BP/HR revaluation
Dermatome assessment
**5 minutes to prevent high spinal**
148
Common Spinal Problems
No flow when you spin the needle 360-advance
No swirl
paresthesia-reposition them
Blood instead of CSF-check it wasnt from the prior insertions
**No block-check dates in your kit, it might've expired**
Parital block
149
Epidural Needles
Tuohy-has the most curvature aobut 30 degrees and blunt tip protects SAB space
**Crawford is used when catheter placement is difficult or steep angle like thoracic- no curvature**
Weiss-has wings, 15 degree curve
150
Epidural Catheter factoids
If your Tuohy has 4 cm outside the patient how much is in the epidural space?
Multi-orifice catheter has better distripution
*optimal epidural space of the needle is 3-5 cm*
**the tuohy is the introducer sheath and is 9cm up to the hub, so 9-4cm means 5cm is in the patients epidural space**
For documentation of placement you put "10cm" at the skin-5 is in the go zone, and 4 is outside plus the cm window thus 10
151
Lumbar Tattoo and Epidural Concern
**Perform after 5 months of the tattoo**
Try to avoid henna or if your spooked it's fine to bail
*chart the concerns and discussion with patients*
152
During epidural how do you find your epidural space
**with the tuohy needle with the tuohy needle**
153
If lumbar epidural started at L4-L5 how many mLs are needed for T10?
start at the level and count backwards but not counting L4. So 6 levels, 1-2 mLs per level so 6-12 mLs
and if you rolled with 6, top up dose would be 3 cm (50%)
**again test with cold temps like a spoon and aspirate just in case of catheter migration to IV or SAB spaces**
154
Lidocaine top up dose time
60 min
155
2-Chloroprocaine top up dose time
45 min
156
Mepivacaine top up dose time
60 minutes
157
Bupivacaine and Ropivacaine
120 minutes
158
Epidural Common Mishaps
CSF "Wet Tap"-overpenetration into dural space and CSF comes out.
Paresthesia-plica might bonk your advance and
Cant advance or thread catheter- again plica
**Aspirate blood- wrong spot, always aspirate slow and give increments**
**Positive test dose, but dont be a goober and give it during a contraction-that'll be a false positive**
159
CSE
Combined spinal epidural
**Spinal is done first, but use Tuohy as introducer**
So find epidural space, then find dura which shouldnt be too much further for the **Pop** drop your LA for spinal
Leave the Tuohy in to thread the epidural catheter-retract tuohy a smidge then thread it
160
In preop if you auscultate and hear a random rhythm and EKG shows Afib and the patient doesnt know do you proceed?
*Nope, Cancelectomy unless you want to throw clots*
161
Beer lambert and Pulse ox light absorption
**Greater solute concentration (more stuff in blood) or greater light path length (vasodilation/more tissue) means more of the stuff in the vein/container is absorbing more light**
162
Pulse ox VS Co-oximetry
Pulse ox looks at 2 wave lengths,
*co-oximetry looks at 4, may be needed with elevated altitudes or COHb*
163
deO2Hb absorbs red light or IR more?
*More red light (660 nm)*
164
O2Hb absorbs more IR or Red light?
*IR light (940nm)*
165
Pulse Ox advantages
in healthy peeps withing ABG ~2% when over 70%
not affected by volatiles
noninvasion
continous
convenient and can pick up **cardiac output**
166
Pulse Ox disadvantages
Poor function in clamped states
Delayed hypoxic detection
Dysrhythmias throw it off-aflutter etc
different Hbs can throw it off
dyes will block the read, optical interference
167
Pulse ox tips
Detection of desaturation is slower peripherally e.g. an endoscope will show it faster
dont put it on index finger, patient could bonk themselves
**with epidural blocks toes would be primo**
**Tongue, cheek, forehead are less affected by vasoconstriction/reflects desatutation**
168
MAP formula
MAP = DP+1/3(SP-DP)
169
BP Auscultation issue
Shock/vasoconstriction states
Severe edema/Atherosclerotic vascular changes
Wrong cuff
**Cuff bladder should be 40% of circumference of arm**
**Bladder should be 80% of length of upper arm, centered over artery**
Extremes in habitus
170
Auto Cuff concerns
uses oscillometry-MAP maybe falsely low during hypertension, falsely high during hypotension
**in ill patients/elders SBP will differ the most than a-line**
Healthy folks it'll be accurate
**Atherosclerosis, edema, obesity and chronic HTN will narrow PP**
*check different arms if not arm surgery*
*Cuff too large- low BP*
*Cuff too small- high BP*
171
Allens' Test
**80% accurate (for 5 second return)**
**if color return to hand takes over 10 seconds-you have reduced collateral flow**
172
Seldinger's technique
Stab with needle
pass guidewire
remove needle
thread catheter
173
A-line tranfixion techinique
Same positioning/prep as Seldinger
stab through front and back wall intentionally
needle removed
catheter is withdrawn slowly until pulsatile flow appears and then is advanced
*supposedly not associated with higher complication rates*
174
A-line optimization
auto NS flus 1-3ml/hr to prevent thrombus
zero to atmospheric air
**level to aortic root**
Maximize waveform- limit stopcocks, tubing length, and **non-distensible tubing (stiff)**
175
What is happening at a-line waveform phase 2, 3, 4, 5, and 6?
Phase 1 is **AFTER the R wave on EKG** and dicrotic notch signifies
176
A-line waveform closer to heart vs periphery
further away, arterial upstroke is steeper, systolic peak higher, dicrotic notch is later and end-diastolic pressure lower
**impedance and harmonic resonance along the vascular tree is why**
177
A-line waveform formation
Fundamental wave+ Harmonic wave
6-10 harmonics are required via **fourier analysis**
178
A-line Underdamping
Waveform looks very artifact heavy
**multiple notches**
179
A-line *overdampening*
Looks like a small hill
**systolic decreased**
**absent dicrotic notch**
**False narrowed PP**
**accurate MAP**
180
Aging changes with Pressures
less distensible/Atherosclerosis contribute to widened pulse pressure
waveform looks jagged/sharper
181
A-line complications
distal ischemia/pseudo aneurysm
hemorrage
arterial embolus
local infection
peripheral neuropathy from trauma/etc
182
Postive Pressure Ventilation effects on pressure during *exhalation*
opposite of inhalation
*decreased* RV stroke volume leads to **reduced LV filling, reduced LV SV, and reduced systemic arterial pressure**
183
Systolic Pressure Variation
in mechanically vented patients **normal is 7-10 mmHg**
basically the swing up of **2-4 mmHg and down 5-6 mmHg, more likely in sickies**
Increased SPV = give fluid/early sign of hypovolemia- means preload reserve is bupkis
so called "pressure swing"
184
What to PPV, SPV and SVV rely on for calculation
Mechancial ventilation of 8-10ml/kg
PEEP of over 5 mmHg
**Regular rate and rhythm**
normal intra-abdominal pressure
**CLOSED CHEST**
185
Frank Starling
Preload response curve
186
Expired gas sampling sites
Y-piece of mask circuit arm
jammed on a facemask
taped to a patient
it varies
187
Total Response time for gas analysis
Transit time- lag for gas to reach analyzer
Rise time- time taken by the analyzer to react to the change in gas concentration
side-stream responses- dependent on sampl
188
Mainstream and Side-stream gas sample shared issue
watervapor will condense in tubing/sampling site and will throw it off
same with vomiting/secretions
189
Mainstream sampling cons
More points for disconnects
blood/secretions will disable it
Rise time is faster, no time delay as it's in the circuit
190
Side-stream sampling issues
**Takes Longer**
Kink in tubing will throw it off
water vapor
**failure of sampling pump-wont have a read at all**
leaks in line - common at the screw in attachment points and with reuse
**Slow response time**
191
Dalton's Law
summative of the parital pressures
e.g. Room air PP is 160mmHg
160 mmHg/760mmHg) x 100% = 21 volumes %
192
Mass Spec vs Raman Spec
Mass we use all the time, concentration of gas versus mass/charge ratio to tell you what percent the gas mixture is of sevo/N20 etc.
**Can calculate 8 separate gasses**
Raman-argon laser blasts the shit of a gas sample to form protons, photon scatter is measured in a spectrum to identify gas and its concentration
NOT USED
193
IR analysis concept
gas has unique IR band absorption
IR light is beamed through a sample, then continues past in a narrow-band filter (simlar to a toy stereoscope) and the light detected = concentration
**Less light detected = higher concentration**
194
Water vapor calculation in gas sampling
*Side stream analyzers report ambient temperatures (ATPD) and DRY pressures*
Analyzers really should sample at body temp and pressure saturated values (BTPS)
whatever just subtract **47mmHg** from a sample to calculate partial pressure
**E.g. O2 at 30% PP? = (760-47)(0.3)= 214 mmHg**
195
Fuel/Galvanic Cell battery
O2 wont be analyzed because its used to measure current as O2 diffuses across the battery membrane
current is proportional to partial pressure of O2 in fuel cell
Short life span, **slow response time-monitor O2 in inspiratory limb**
196
Paramagnetic
detects sample line pressure changes from attraction of O2 and its mag field changes
signal change correlates with O2 concentration
**used in most side-stream sampling**
**Rapid interpretation- breath by breath**
*changes in ETCO2 can be faster than
197
Oxygen monitoring
Most important
**Calibrate for high and low concentrations**
**sample from Inspiratory limb, indicates if your air mixture is enough in your mix**
**tells you when denitrogenation is complete and ETO2 is 90% and above
198
Low O2 alarm causes
Pipeline crossover (OR hoses are swapped like N20 with O2)
Tanks on the back are filled wrong
**Failure of the proportioning system e.g. N2O**
199
High O2
**dont give 100% to premies and homies on bleomycin**
200
Airway pressure monitoring
look at the gauge/monitor, keeps you keyed in about ventilation, kinks, ETT occlusions or issues in the scavenging system
mechanical pressure gauges are always on and highly reliable-no recording
electronic gauges are integrated in the circuit
*circuit disconnects will be the most common offender*
201
Pressure alarms
Mostly for circuit disconnect/leaks
*doesnt pick up on partial leaks, low pressure limit should be just below normal peak airway pressure*
**70% of disconnects occur at Y piece**
202
Sub atmosphereic pressure alarm
measures/alerts circuit pressure for *reverse flow of gas*
negative pressures are super spooky- **flash pulmonary edema, atelectasis can occur**
can stem from suction scavenging malfuction
**PATIENT BREATHING AGAINST BLOCKED CIRCUIT LIKE LARYNGOSPASM**
whack fresh gas flow
suction to NGT/OGT in wrong spot
CO2 absorber is too moist
203
High pressure alarms
activate if pressure exceeds a limit
useful in pediatrics
usually caused by eh compliance lungs, coughing/straining kinked ETT, *endobronchial intubation*
204
What do continued pressure alarms mean for you
10 cm H20 over 15 seconds
*Fresh gas continues to enter circuit but cant exit*
APL valve is whack, scavenging system is occuluded, or you activated the O2 flush are usually why
PEEP malfunction also contributes
205
Types of nerve monitoring
Electronic and magnetic
*Magnetic sucks because its heavy, bulky, no TOF function and hard to illicit upramaximal effect (all or none stimulation pattern)*
*how many nerves activated determines muscle response*
206
What muscle is last to be knocked out and quickest to recover from paralytics
Diaphragm baby
207
Single twitch
single twich 1 Hz (each second) to 0.1 (each 10 seconds)
*need a reference before NMBD*
208
TOF
4 supramax stimuli every 0.5 seconds
TOFR is last response to 1st
**Partial ND block- TOFR decreases/fades and is inverse to degree of block**
e.g. immediately after NMBD expect 0 twitches, 20 minutes later the fade
209
Partial Depolarizing block
**No fade, ratio is 1:1**
**IF FADE IS PRESENT WITH DEPOLARIZING BLOCKADE YOU HAVE PHASE 2**
210
Double burst
2 short bursts of 50Hz
3.3 mode is 3 impulses in each of the 2 bursts
3.2 first burst hast 3, 2nd burst has 2
essentially compares the first twitch with the fade of the second twitch
211
Tetanic stimulation
50 Hz for 5 seconds, zaps the shit out of the patient
Non-depolarizing agents- one strong sustained contraction **with fade after stimulation**
painful and again less clinical utility
212
Tetanic stimulation with Depolarizing NMBD
Depolarizer agent- strong sustained contraction **without fade**
*if fade is present in depolarizing block-Phase 2 has occured*
*think pseudocholinesterase patients or sux readmission*
213
Post-tetanic Stimulation
Composite stim- 50hz for 5 seconds, then after a 3 second pause 10-15 single zaps at 1 Hz.
depends on blockade
frequency/duration of tetanic stim
frequency of single twitch stimulation
*for deep surgical blockade, done every 6 seconds*
214
Depolarizing Blockade
Phase 1- no fade or tetanic stimulation, post tetanic also absent
All 4 responses are reduced **but equal** and then disappear at the same time
**normal plasma cholinesterase**
Phase 2- **fade present in TOF and tetanic stim- post tetanic stimulation faciculation present also**
resembles non-depolarizing blockade
**abnormal plasma cholinesterase activity**
215
Peripheral Nerve stimulation caveats
Keep them warm-cold nerves dont respond as well
attach old school probes before induction and turn on after unconsciousness
**Moderate blockade is fine at 1-2 responses to TOF, tell surgeon womp womp**
Reverse at 4/4 TOF otherwise delayed recovery and will have issues
**Check for head lift 5 seconds, leg lift for 5 seconds, hand grip for 5 seconds, or max inspiratory pressures**
216
EEG stuff
looks at excitatory and inhibitory PS potentials
electrodes correlate with surface area over cortical regions **uses at least 16 channels
identifies: awake, zonked, seizure activity, stages of sleep, coma
**hypoxemia or ischemia as well**
Amplitude-size/voltage of signal
Frequency-number of hits/oscillations over 0-voltage line
Time-duration of sample signal
217
EEG OR uses
used to ID cerebral cortex ischemia
correlates anesthetic CRMO2 reduction
can be used to correctly gauge hypnotic state and if anesthetics need to be dialed back
can predict outcome after brain insult
218
EEG waves
Beta- over 13 Hz- awake and alert
219
EEG Alpha wave
8-13 Hz- eyes closed
**So 10Hz on the exam, put anesthesia/asleep**
**ideally where you want your patients-alpha land**
220
EEG Theta and Delta
Theta 4-7hz
Delta less than 4 hz
they be depressed
*slower frequency and lower amplitude*
221
BIS/Processed EEG
Compresses 4 channels into one wave form, **2 channels per hemisphere**
**both hemispheres are necessary to check if both sides are good, or if one is rekt from carotid clamping**
has artifact with the EEG signal so chart why if you ditched it
222
BIS
0- flat line
100- awake
**60-40** should be GA land, no response to verbal stimulus or likelihood recall
**again not bulletproof compared to endtidal agent monitoring- if youre giving 2.2% sevo and they have 2.2% on Fe they zonked zonked**
223
Sensory-Evoked Responses
Most common evoked potentials used
CNS zaps intraop in spine/neuro cases to assess nerve anatomy integrity- looks at the cortical, subcortical, and periphery
**described in latency-time to response after the zap
amplitude-size/voltage of recorded zap to baseline**
224
SSEPs
Monitor peripheral motor and sensory nerve stimulation and sensorimotor cortex response
Mostly will use short latency SSEPs as anesthesia will prevent the longer ones
Induction, neurological age, or different electrode locations can alter the SSEP waves
225
BAEP
*Brainstem Auditory Evoked Potentials*
**foam earplug inserts send a click in the ear to the auditory cortex, and the brainstem response is recorded**
226
VEP
Visual Evoked potential
weird light goggles send a flash stimulating retina and response is recorded
**again SSEP will be the most common**
227
Motor-Evoked Potentials
Monitors signaling over the motor tracts, spinal columns, peripheral nerves, and innervated muscle for boo boos
**Transcranial motor-evoke potentials are the most common MEP**
**looks at the stimuli along motor tract via transcranial zaps overlying the motor cortex**
228
Electromyography
monitors cranial and peripheral motor response to zaps to **alert early detection of surgical damage and assess nerve function**
**looks at cranial or peripheral nerves at risk during surgery**
229
Temperature monitoring
**Primary thermocontrol-hypothalamus**
Unmyelinated C fibers - heat and warmth receptors
Alpha and delta fibers - cold receptors
**Response is dictated by:
Threshold-is the temp low/high enough to get a response
Gain- how intense is the stimulus
Response-does the temp force sweating, vasodilation/constriction, or shivering**
Anesthesia, age, menstral shit, drugs, ETOH, and circadian will alter it
230
GA hypothermia
**initally 0.5 to 1.5 C from anesthesia induced vasodilation, further heat loss from body heat reduction that occurs over 30min**
**next slow linear reduction at 0.3 C per hour, GA reduces metabolic rate by 20-30% as heat loss exceeds production 1-2 hours after anesthesia
**3rd is plateau steady state, heat loss and production are the same, vasoconstriction prevents core heat loss but periphery still has heat bleed**
231
Neuraxial Hypothermia
Patients wont complain of feeling cold-epidural will block the C fibers
Heat loss may not reach plateau phase as peripheral vasoconstriction threshold is altered/doesnt occur
**Neuraxials decrease thresholds that trigger peripheral vasoconstriction and shivering-central thermoregulation is off**
**Autonomic thermoregulation defenses impaired so techincally sweating, vasodilation, shivering, and vasoconstriction are impaired**
232
Radiation
heat loss to environment- **40% of patient heat loss**
Body surface area exposed to environment and babies have a high BSA/body mass ratio making them vulnerable
233
Convection
Loss of heat to air immediately surrounding the body **approximately 30%**
*clothes/draping decreases loss, increased in rooms with laminar flow*
234
Evaporation
**latent heat of vaporization of water from open body cavities, resportory tracts-8-10%**
*sweating is the main pathway, in ex-laps saline soaked gauze averts it*
*excessive sweating under GA should set off your spidey senses-check a sugar probably hypoglycemic*
235
Conduction
heat loss from direct body tissue contact with cold fluids/materials, is negligible
e.g. contact between skin and OR table, IV compartment and cold iv infusion during MH event
236
Hypothermia Benefits
Protects against cerebral ischemia
**Reduces metabolism 8% per degree celsius**
MH theorhetically will be harder to trigger
useful in NSGY with expected ischemia
Improves cardiac arrest recovery
237
Peri-Op temp management
airway heating/humidification in circuit **more seen in peds**
warm IV fluids and blood-prevents cooling
Skin warming- **keep room temp higher in liver xplants, trauma, peds**
Insulation as well with blankets, slows loss by 30%
Hot water mattress-*more effective and safe on top of patient*
Forced air warming-more common and prevent loss from radiation, **e.g. bair hugger using convection**
238
Temp monitoring sites
P.A. is the gold standard but eh were getting away from it- correlates with tympanic, distal esophageal, and nasopharyngeal temps
**Tympanic temps-approximates hypothalamustemp, but can perf it**
Nasopharyngl reflects brain temp but is prone to errors, nose bleeds
Esophagus-safe, accessible, accurate **place in lower third/fourth of esophagus**
239
OR Temperature generally
**70F or 21C for peds**
65F or 18C
240
Capnography big picture
Tells us about ventilation, metabolism, and CV
*what goes in must come out*
*to a lesser extent can tell us pulm blood flow, aerobic metabolism, ETT/LMA placement, breathing circuit integrity and CO*
**If ETCO2 drops off randomly-check the circuit and swap it out and it should return**
**compressions are on point if ETCO2 returns**
241
Hypercarbia effects
Respiratory Acidosis
Increase in CBF-**ICP risk in neuro patients-back off on opioids**
Pulmonary Vascular Resistance
K shifts from intracellular to intravascular
242
Bohr Equation
**Calculates physiological dead space to tidal volume**
243
Dead space
Mouth to just before gas exchange regions of lungs
*150ish ccs for this class*
244
Anatomic deadspace
conducting zones of airway-nose, trachea, bronchi
245
Physiologic deadspace
airway deadspace+**alveolar dead space**
Alveolar dead space- physio deadspace not exchanging gas in the **alveolar space**
246
Causes of Alveolar Deadspace (V/Q mismatch)
Hypovolemia
Pulm HTN
PE
Ventilation of nonvascular airspace
precapilary obstruction pulm vessels
Obstruction of pulmonary circulation from outside forces
Alveolar distention
247
Capnometry
Measurement and quantification of inhaled or exhaled CO2 as measured by capnometer
248
Capnography
method of CO2 measurement *and graphic display of time, breath to breath*
**outside of CXR best way to confirm intubation**
**we want three accurate, strong wave forms**
249
Time capnography
Pressure vs Time plot-most common representation
CO2 concentrations are recorded as inspired or end tidal
Highspeed-shows detail of each breath shows nice detail of each one
Slowspeed-shows trend looks all squiggly
*strips look opposite of what youd think*
250
ETCO2 measurement location
at the end of phase 3
**usually just prior to inspiration, is the largest value but can vary manufacturer to manufacturer**
**will be asked "is it end of expiration" on exam-yes it is**
251
Arterial/ETCO2 difference
5 mmHg, so ETCO2 of 35 means arterial ETCO2 is 40mmHg
*V/Q mismatch increases the difference of PaCO2 and PACO2-PE or Endobronchial intubation*
COPD, bronchospasm, and neonate breathing can make it worse
*Capnograph can have an issue and will tell you to recalibrate if slow response time to breathing pattern, or sample catheter has a leak*
252
Noninvasive McGuyver ETCO2 method
jam the sample line in a face mask and tape the side vents, or Nasal cannulas will have it in the cannula
253
Clinical measurement of ETCO2
IR light absorption-greater CO2 in sample, less IR light reaches detector
Chemical indicators turn pH paper yellow if CO2 is present-sensitive to low CO2 but ETT needs second verification as it could be in the esophagus
254
ETCO2 monitor requirements
CO2 Read must be withing 12% of actual value
manufactures has to disclose if ethanol, acetone, or halogenated requirements
**Must have a high CO2 alarm for inhaled and exhaled CO2**
**Must have a low exhaled CO2 alarm**
255
Time Capnogram Interpretation
interpreting CO2 values, approximate blood CO2 levels, Pulmonary Blood Flow, and Alveolar Ventilation can be inferred by capnogram
**DDx of loss of exhaled CO2- Goose egg intubation, accidental extubation, sample line disconnect, apnea, bronchospasm or cardiac arrest**
Inspiratory - phase 0 the down slope
**Expiratory- phase 1, 2, and 3**
256
ETCO2 Phase 3
plateau phase, representative of CO2 in alveolus, **indicator of ventilation heterogeneity, slight increaseing slope-not all alveoli close at the same time otherwise it wouldnt have a slope**
257
ETCO2 Phase 4
**phase4isphase0phase4isphase0**
inspiration of fresh gas is washing out remaining CO2, downstroke returns to baseline
258
Occasional Phase 4
sharp upstroke in PCO2 at the very end of Phase 3, resulting from closure of lung units with lower PCO2 causing a little upstroke at the end of the ETCO2 waveform
**Commonly seen in pregnant/obese patients-decreased FRC and LC**
**also denoted as Phase 4'**
259
Beta angle
separates Phase 3 and Phase 0
90 degreesish, can widen with **malfunctioning inspiratory uni valves, rebreathing, or guppy breathing(high RR, low TV)
260
Normal Capnograph
261
Inadequate ETT Cuff seal
Beta angle falls off as room air is being entrained around tube and Phase 3 is cut short
262
Sample Line Leak
Note the read capping at 20mmHg
*it's half normal as the line is probably broken and room air is diluting the expired sample*
**the end jump is not phase 4 prime it's not at 40mmHg nor an FRC/LC issue from being fat**
263
Hyperventilation wave form
Light anesthesia, Metabolic acidosis is leading to higher RR
264
Hypoventilation capnography
ETCO2 is climbing
MH, Sepsis, fever, narcotics, hyperthyroidism, hypoventilation
265
Airway obstruction capnograph
sharkfin, alpha angle is gone
phase 2 and 3 have merged
266
Vent overbreathing
Patient is intiating breaths between mechanical breaths-if its a large wave they dont need support just dial in narcotics to 12-20 RR
*with smaller patient breaths/wave theyre weak you could flip the vent off and close the APL valve a bit and depress the bag to support the tidal volume goal or reparalyze them/blast them fent*
