Relative contraindications for Manual Vent. for General anesthesia?
Full stomach or Rx for aspiration
Anticipated/known difficult airway
What are these & why use?
Ring, Adair, Elwin (RAE) ETTs
For nasal intubations
What benefit does Miller offer over MAC?
(but you have to have total control of tongue)
How many receptors are blocked when you loose the 3rd Twitch?
85 % of receptors blocked
What is Electromyography (EMG)?
- Based on measurement of muscle compound action potential that occurs with muscle membrane depolarization (electrical not mechanical)
- used at UIHC - uses small amp (20 mv) w/ 100-350 volts
- JUST SHOWS MEMBRANE DEPOLARIZATION - not contraction, either on or off.
Self Inflating mask
What is a Train of four ratio measuring?
Amplitude of 4th twitch/ amp of 1st twitch
When TOF >70-80% = 20% receptors arent blocked and normal muscle contraction should occur
What does Pre-Oxygenation do?
Fills FRC (approx. 2.5 Litres)
What is Post tetanic Count (PTC)?
- 50 Hz tetanic stimulation for 5 sec; wait 3 sec; then supramaximal stimulus at 1 Hz
- If 5-7 responses are detectable after tetanic stimulation, return of TOF response is imminent.
TOF Less than .90 is associated w/?
Functional impairments of the pharynx & lower esophagus
Increasing aspiration and Post op complications
How many receptors are blocked when you loose the 4th Twitch?
75-80% blocked post synaptically
APSF Prevention Focus: Avoiding preventable injury by 7 necessary components?
1. Reliable delivery of Oxygen at any concentration up to 100%
2. Reliable means of positive pressure ventilation (PPV)
3. Backup vent.
4. Controlled release of PPV
5. Anesthetic Vapor delivery - if part of plan
6. Adequate Suctioning
7. Conform to standards of monitoring - ACLS/PALS
What is FRC?
FRC: Lung volume at end of normal exhalation.
FRC, the elastic recoil forces of the lungs and chest wall are equal but opposite and there is no exertion by the diaphragm or other respiratory muscles
How many receptors are blocked when you loose the 2nd Twitch?
Who may benefit from a Oral airway?
- Edentulous patients
- Down syndrome and pediatric patients with large tongues
- Sleep apnea patients
- Never really hurts to place one (be careful with loose teeth)
- Make sure patient is deep enough
How to treat Laryngospasm?
Forward displacement of the jaw and apply positive pressure with 100% oxygen
• Severe spasm may require small doses of succinylcholine (0.1 to 1 mg/kg) and re-intuba&on. – May be given intramuscularly or by sublingual injection.
• Laryngospasm will eventually cease as hypercarbia and hypoxia develop.
Flow inflating Bag Mask
Gas can ONLY exit from an ______ if no other leaks exists in a vent. circuit.
APL valve - adjustable pressure Limit or "pop off" valve
What has to be present to get a TOF ratio?
What is Mechanomyography?
Classic gold standard
Uses Add Pol. Based on isometric measurements of muscle force
Manual Ventilation Peak pressure upper limit?
20 cm H2O
How many receptors are blocked when you loose the 1st(aka ALL) Twitches on a TOF?
What kind of blade is this?
Laryngospasm is controlled by which nerve?
superior laryngeal nerve
“gold standard” for anticipated difficult airway
Flexible Fiberoptic Laryngoscopes (Bronchoscopes)
What is accleromyography?
New gold standard
- Uses force = Mass * acceleration
muscle force is directly proportional to muscle acceleration
***have to use adduct. Pollicis ==> extremity cant be immobile***
What kind of blade are these?
Optimal position for intubation
Ramped, sniffed position
What TOF ratio is considered adequate reversal?
At least .8 (.90 is better)
How to pick a ETT for pediatric patients?
– ID ~ Age divided by 4 + 4
– Compare diameter of ETT to pinky size
– Depth = ~ ETT size x 3 (4.0 X 3 = 12cm deep)
Pressure (BP) = ______ X ________
Flow ( CO= HR X SV)
Resistance (SVR & PVR)
How is Oxygen Content of blood measured?
(Hemoglobin X Saturation % X 1.34) + (PaO2 X 0.003)
MAP = _______ X ________
CO (SV * HR) x SVR
3 Factors that control Stroke Volume?
Best Indicator of Tissue perfusion?
Pulse Pressure = ???
Systolic pressure - diastolic
(Reflects diff. in volume ejected from LV into arterial vessels and the volume already there)
Causes for Wide PP variation?
Difference between manual BP measurements and Automated?
Automated measures MAP from MAX oscilation amp. and deduces systolic and diastolic
(Diastolic P is the most unreliable measure w/ automatic)
MANUAL - uses Korotkov sounds to measure SBP & DBP
What happens when SBP is less than 80 w/ NIBP cuff?
MAP is often overestimated
BP Cuff length and Width?
Length = 80% circumference of arm
Width = 40% arm circumference
Reasons for Inserting Art line?
– Hemodynamic instability or predicted instability.
– Surgical procedure with antcipated significant blood loss or fluid shifts
– Monitoring of induced hypotension
– Monitoring response to vasoactive drugs
– NIBP is not feasible (burns, obese, shock)
– Repeated blood sampling
What happens to Art lines as the are placed more distally?
greater distance from aortic arch = Higher SBP & greater variability
What always remains constant in dampened and hyperressonant Art line waveforms?
MAP & DBP
a - atrial contraction, absent in a fib, larger in tricuspid stenosis, pulmonary stenosis and pulmonary HTN
• c – due to bulging of tricuspid valve into RA
• x - atrial relaxation
• v - rise in arterial P before tricuspid valve opens
• y - atrial emptying as blood enters ventricle
Pulse Pressure variation level responsive to fluid?
Fluid responsive Systolic Pressure Variation?
How to deflate balloon during PA cath check?
Always deflate passively
Normal PA pressures & Wedge Pressures?
S - 15-30 mmHg
D - 5-15 mmHg
Wedge (PACWP) - 4-14 mmHg (true LV preload)
Lead II Covers?
Lead V5 covers?
2 - Inferior portion of the heart supplied by the RCA
5 - Bulk of LV supplied by LAD
(2 most common used leads in OR)
What major vessel is missed w/ just lead 2 & 5?
Circumflex artery - lead 1
Measures movement of the chest electrodes.
Difference in light absorbance between oxyHb & DeoxyHB?
OXY - absorbs more infrared Light (940nm) than red light
DEOXY (REDuced) - absorbs mre red light (660nm) than infrared light
If Saturation is at 85% regaurdless of changes in oxygen?
Think - Methemoglobin - (benzocaine & Meth