Anaesthetics at WWBH Flashcards
Anesthesia Definition
Anesthesia: lack of sensation/perception
Toronto notes 2016
4 steps to Anaesthetics
- pre-operative assessment
- patient optimization
3. plan anesthetic various types of anesthesia pre-medication airway management monitors induction maintenance extubation
- Post-operative care
Toronto notes 2016
6 As of General Anesthesia
Anesthesia Anxiolysis Amnesia Areflexia (muscle relaxation not always required) Autonomic stability Analgesia
Toronto notes 2016
Types of Anesthesia
- general
- regional
- local
- sedation
Toronto notes 2016
Evaluation of Difficult Airway:
LEMON Look – obesity, beard, dental/facial abnormalities, neck, facial/neck trauma Evaluate – 3-2-1 rule Mallampati score Obstruction – stridor, foreign bodies Neck mobility
Toronto notes 2016
To Assess for Ventilation Difficulty:
To Assess for Ventilation Difficulty: BONES Beard Obesity (BMI>26) No teeth Elderly (age>55) Snoring Hx (sleep apnea)
Toronto notes 2016
Classification of oral opening
Mallampati
1. full view of uvula (body and base of uvula), can see tonsillar pillars
2 body and base of uvula, tonsillar pillars and tonsils (partial view)
3 base of uvula and post-pharyngeal wall
4 hard palate and no other structures visible
• routine pre-operative investigations are only necessary if there are comorbidities or certain
B
Chest Radiograph
C
ECG
B-hCG
Electrolytes and Creatinine
Fasting Glucose Level
H
CBC
Sickle Cell Screen
INR, aPTT
American Society of Anesthesiology Classification
• common classification of physical status at the time of surgery
• a gross predictor of overall outcome, NOT used as stratification for anesthetic risk (mortality rates)
• ASA 1: a healthy, fit patient
• ASA 2: a patient with mild systemic disease
ƒ e.g. controlled Type 2 DM, controlled essential HTN, obesity, smoker
• ASA 3: a patient with severe systemic disease that limits activity
ƒ e.g. stable CAD, COPD, DM, obesity
• ASA 4: a patient with incapacitating disease that is a constant threat to life
ƒ e.g. unstable CAD, renal failure, acute respiratory failure
• ASA 5: a moribund patient not expected to survive 24 h without surgery
ƒ e.g. ruptured abdominal aortic aneurysm (AAA), head trauma with increased ICP
• ASA 6: declared brain dead, a patient whose organs are being removed for donation purposes
• for emergency operations, add the letter E after classification (e.g. ASA 3E)
Layers traversed by spinal needle
google: The layers traversed by the spinal needle are the skin, subcutaneous tissue, supraspinous ligament, interspinous ligament, ligamentum flavum and the dura
max dose of ligdocaine
Trilon said 2mg/kg
Lx spinous processes found between iliac crests
L4 spinous processes found between iliac crests
Preoperative medication to stop: oral antihyperglycemic
stop morning of surgery
Preoperative medication to stop: antidepressant
stop on morning of surgery
Preoperative medication to stop:
ACE inhibitors and angiotension receptor blockers
may stop on morning of surgery (controversial)
Preoperative medication to stop:
ASA, NSAIDs
discussed with surgeons
Preoperative medication to stop:
ASA in non-cardiac surgery
in patients undergoing non-cardiac surgery, starting or continuing low-dose aspirin in the perioperative period does not appear to protect against post-operative MI or death, but increases the risk of major bleeding
– note: this does not apply to patients with bare metal stents or drug-eluting coronary stents
3 medications to adjust in pre-operative period
• insulin (consider insulin/dextrose infusion or holding dose), prednisone, bronchodilators
BP targets perioperatively
BP <180/110 is not an independent risk factor for perioperative cardiovascular complications
• target sBP <180 mmHg, dBP <110 mmHg
• assess for end-organ damage and treat accordingly
• ACC/AHA Guidelines (2014) recommend that at least x days should elapse after a MI before a noncardiac surgery in the absence of a coronary intervention
60
- this period carries an increased risk of reinfarction/death
mortality with perioperative MI is x
20-50%
perioperative β-blockers
-may decrease cardiac events and mortality (controversial, as recent data suggests increased stroke risk)
continue β-blocker if patient is routinely taking it prior to surgery
- consider initiation of β-blocker in: patients with CAD or indication for β-blocker OR intermediate risk surgery, especially vascular surgery
smoking effect on physiology that negatively impacts surgery
adverse effects: altered mucus secretion and clearance, decreased small airway caliber, and altered immune response
how long to abstrain from smoking preoperatively
abstain at least 8 wk pre-operatively if possible
if unable, abstaining even 24 h pre-operatively has shown benefit
avoid non-selective β-blockers due to risk of x
bronchospasm
delay elective surgery for poorly controlled asthma
delay elective surgery for poorly controlled asthma (increased cough or sputum production, active wheezing)
delay elective surgery by a minimum of x wk if patient develops URTI
6
pre-operative x for all COPD stage x patients to assess baseline respiratory acidosis and plan post-operative management of hypercapnea
cancel/delay elective surgery for x
ABG
Stage II and III
acute exacerbation
β1-receptors are located primarily in the x
heart and kidneys
β2-receptors are located in the x
lungs
Cardioselective Beta blockers for B1
MANBABE
Metoprolol Atenolol Nebivolol Bisoprolol Acebutolol Betaxolol Esmolol
Fasting guidelines•
x h after a meal that includes meat, fried or fatty foods
8
Fasting guidelines•
x h after a light meal (such as toast or crackers) or after ingestion of infant formula or nonhuman milk
6
Fasting guidelines•
• x h after ingestion of breast milk
4
Fasting guidelines•
x h after clear fluids (water, black coffee, tea, carbonated beverages, juice without pulp)
2
What to do for addison’s disease intraoperatively
consider intraoperative steroids
The only indispensable monitor
the anaesthetist
Inadequate anesthetic depth
blink reflex present when eyelashes lightly touched, HTN, tachycardia, tearing or sweating
excessive anesthetic depth
hypotension, bradycardia
resistance to airflow through nasal passages accounts for approximately x of total airway resistance
2/3
pharyngeal airway extends from
posterior aspect of the nose to cricoid cartilage
what is glottic opening
triangular space formed between the true vocal cords
What is the triangular space formed between the true vocal cords
glottic opening
Which vertebrae does the trachea begin at?
C6
Trachea bifurcates at which vetebral level?
T4-T5 (approximately the sternal angle)
- non-definitive airway (patent airway)
ƒ jaw thrust/chin lift
ƒ oropharyngeal and nasopharyngeal airway
ƒ bag mask ventilation
ƒ laryngeal mask airway
- definitive airway (patent and protected airway)
ƒ endotracheal tube
ƒ surgical airway (cricothyrotomy or tracheostomy)
LMA sizing
3: 40-50
4: 50-70
5: 70-100
• align the three axes (x, x, x,) to allow
mouth, pharynx, and larynx
sniffing position
ƒ “sniffing position”: flexion of lower C-spine (C5-C6), bow head forward, and extension of upper C-spine at atlanto-occipital joint (C1), nose in the air
ƒ contraindicated in known/suspected C-spine fracture/instability
• laryngoscope tip placed in the epiglottic x in order to visualize cord
epiglottic vallecula
Medications that can be Given Through the ETT
NAVEL Naloxone Atropine Ventolin Epinephrine Lidocaine
laryngoscopy and ETT insertion can incite a significant sympathetic response via stimulation of cranial nerves x and x due to a “foreign body reflex” in the trachea, including x
9 and 10
including tachycardia, dysrhythmias, myocardial ischemia, increased BP, and coughing
• a malpositioned ETT is a potential hazard for the intubated patient
- if too deep, may result in x
deep, may result in right endobronchial intubation, which is associated with left-sided
atelectasis and right-sided tension pneumothorax
• a malpositioned ETT is a potential hazard for the intubated patient
- if too shallow, x
- if too shallow, may lead to accidental extubation, vocal cord trauma, or laryngeal paralysis as a result of pressure injury by the ETT cuff
• the tip of ETT should be located at the midpoint of the trachea at least x cm above the carina and the proximal end of the cuff should be placed at least x cm below the vocal cords
- approximately x cm mark at the right corner of the mouth for men and x cm for women
• the tip of ETT should be located at the midpoint of the trachea at least 2 cm above the carina and the proximal end of the cuff should be placed at least 2 cm below the vocal cords
- approximately 20-23 cm mark at the right corner of the mouth for men and 19-21 cm for women
Confirmation of Tracheal Placement of ETT
direct
vs
• indirect
direct
- visualization of ETT passing through cords
- bronchoscopic visualization of ETT in trachea
• indirect
- ETCO2 in exhaled gas measured by capnography
- auscultate for equal breath sounds bilaterally and absent breath sounds over epigastrium
- bilateral chest movement, condensation of water vapour in ETT visible during exhalation and no abdominal distention
- refilling of reservoir bag during exhalation
- CXR (rarely done): only confirms position of the tip of ETT and not that ETT is in the trachea
Esophageal intubation suspected when
• esophageal intubation suspected when
- ETCO2 zero or near zero on capnography
- abnormal sounds during assisted ventilation
- impairment of chest excursion
- hypoxia/cyanosis
- presence of gastric contents in ETT
- distention of stomach/epigastrium with ventilation
Complications During Laryngoscopy and Intubation
Complications During Laryngoscopy and Intubation
• dental damage
• laceration (lips, gums, tongue, pharynx, esophagus)
• laryngeal trauma
• esophageal or endobronchial intubation
• accidental extubation
• insufficient cuff inflation or cuff laceration: results in leaking and aspiration
• laryngospasm (see Extubation, A18 for definition)
• bronchospasm
Differential Diagnosis of Poor Bilateral Breath Sounds after Intubation
Differential Diagnosis of Poor Bilateral Breath Sounds after Intubation DOPE Displaced ETT Obstruction Pneumothorax Esophageal intubation
• if difficult airway expected, consider
- awake intubation
- intubating with bronchoscope, trachlight (lighted stylet), fibre optic laryngoscope, glidescope, etc.
• if intubation unsuccessful after induction
• if intubation unsuccessful after induction
- CALL FOR HELP
- ventilate with 100% O2 via bag and mask
- consider returning to spontaneous ventilation and/or waking patient
• if bag and mask ventilation inadequate
• if bag and mask ventilation inadequate
- CALL FOR HELP
- attempt ventilation with oral airway
- consider/attempt LMA
- emergency invasive airway access (e.g. rigid bronchoscope, cricothyrotomy, or tracheostomy)
small decrease in saturation below SaO2 of x% corresponds to a large drop in arterial partial pressure of oxygen (PaO2)
small decrease in saturation below SaO2 of 90% corresponds to a large drop in arterial partial pressure of oxygen (PaO2)
cyanosis can be detected at SaO2
cyanosis can be detected at SaO2 <85%, frank cyanosis at SaO2 = 67%
nasal prongs, nasopharynx acts as an anatomic x that collects O2
nasopharynx acts as an anatomic reservoir that collects O2
- delivered oxygen concentration (FiO2) can be estimated by adding x% for every additional litre of O2 delivered
- provides FiO2 of 24-44% at O2 flow rates of 1-6 L/min
- delivered oxygen concentration (FiO2) can be estimated by adding 4% for every additional litre of O2 delivered
- provides FiO2 of 24-44% at O2 flow rates of 1-6 L/min
hudson mask
ƒ fed by small bore O2 tubing at a rate of at least x L/min to ensure that exhaled CO2 is flushed through the exhalation ports and not rebreathed
ƒ fed by small bore O2 tubing at a rate of at least 6 L/min to ensure that exhaled CO2 is flushed through the exhalation ports and not rebreathed
provides FiO2 of x% at O2 flow rates of 10 L/min
provides FiO2 of 55% at O2 flow rates of 10 L/min
non-rebreather mask
ƒ a reservoir bag and a series of one-way valves prevent expired gases from re-entering the bag
ƒ during the exhalation phase, the bag accumulates with oxygen
ƒ provides FiO2 of x% at O2 flow rates of 10-15 L/min
80
Venturi mask
ƒ delivers specific FiO2 by varying the size of x
ƒ oxygen concentration determined by x and x
Venturi mask
ƒ delivers specific FiO2 by varying the size of air entrapment
ƒ oxygen concentration determined by mask’s port and NOT the wall flow rate
What is the common name for assist-control ventilation
volume control
in basic pg 41 it says
assist-control = volume control = IPPV = volume control
high-frequency oscillatory ventilation (HFOV)
ƒ high breathing rate (up to x breaths/min in an adult), very low tidal volumes
ƒ used commonly in x
ƒ used in adults when x
high-frequency oscillatory ventilation (HFOV)
ƒ high breathing rate (up to 900 breaths/min in an adult), very low tidal volumes
ƒ used commonly in neonatal and pediatric respiratory failure
ƒ used in adults when conventional mechanical ventilation is failing
Causes of hypocapnea
hyperventilation
hypothermia
Decreased pulmonary blood flow
Technical issues
V/Q mismatch
causes of Hypercapnea
hypoventilation
hyperthermia and other hypermetabolic states
improved pulmonary blood flow after resuscitation or hypotension
technical issues
low bicarb (i don’t understand this)
Positive End Expiratory Pressure (PEEP)
• Positive pressure applied at the end of ventilation that helps to keep alveoli open, x V/Q mismatch
decreasing
