Startprep 1 Flashcards
Pressure control vs support ventilation
Support: always pt-triggered; flow-cycled
Control: pt- or machine-triggered; time-cycled
In pressure-support, inspiration is terminated by ?
When inspiratory flow falls to a certain percentage (typically 25%) of peak inspiratory flow
Decelerating flow waveform in volume control
lower peak inspiratory pressure
In volume-control, which ventilator settings affect peak inspiratory pressure?
- TV
2. Inspiratory flow
What does a ventilator control?
- Volume
- pressure
- flow
- time
assisted vs controlled breath?
Assist control breath (hybrid mode)
- assisted: Pt initiates breath, which then triggers the ventilator.
- controlled: Ventilator initiates breath based on values prescribed by clinician.
auto-peep
Given that the alveoli are propped open by the positive pressure you are giving and not allowed time to deflate, this phenomenon is also known as auto-peep.
breath stacking
each breath is increasing the volume of lungs in the thorax
Assist-control mode (AC)
Detect pt-triggered breath—–>deliver full ventilator driven TV
Coronary perfusion pressure
DBP - LVEDP
Mitral vs tricuspid vavle
- MV: anterior & posterior leaflet
2. TV: septal, anterior, posterior leaflet
aorta
- intima
- media
- adventitia
coronary circulation
- Aortic root—>L & R Ostia–>L & R coronary artery
2.
SA node (Sinoatrial node)
- @ junction of SVC & RA
- single nodal artery: RCA (55-60%), LCX (40-45%)
- 60-100 bpm
AV node
- @ A-V junction
- 40-55 bpm
- RCA (80%), LCX (20%)
Note: SA–>atrial–>AV node–>bundels of His–>Purkinje fibers (slowest)–>
Heart-Ach
M2
Components of AV valve
leaflets, annulus, chordae, papillary muscles
phase of ventricular relaxation
(1) Isovolumetric: energy dependent
(2) Rapid filling phase
(3) Slow filling=diastasis (5%)
(4) Final filling during atrial systole (15-25%)
Baroreceptor reflex
carotid sinus reflex
- Maintenance of BP
- Carotid Sinus & aortic arch: circumferential & longitudinal receptors
- HTN–>(-) symp–>(-)HR, contractility, vascular tone; HypoNT–>reverse
- Blunt: anesthetics
Chemoreceptor reflex
- Carotid & aortic bodies: chemosensitive cells–>pH, PO2
- PaO2sinus nerve of Hering or Vagus–>medulla–>+ventilation
- para or symp via adrenal
Bainbridge reflex =atrial reflex
- stretch receptor: RA & cavoatrial junction
- (+) stretch—>vagal afferent—>CV center in medulla–>(-)para–>(+) HR
- EA or SA–>(-)sym–>vasodilation–>(-)atrial stretch–>(-)HR
Bezold-Jarisch reflex (BJR)
- noxious ventricular stimuli—> chemo- & mechano-receptors: LV wall–>hypoTN, bradycardia, coronary A dilatation
- bradycardia: atropine
Valsalva Maneuver
think
Cushing reflex
- Increased ICP–>medullary vasomotor center ischemia–>+symp–>HTN–>reflex bradycardia; –>irregular breathing or apnea
- Cushing’s triad: HTN, bradycadia, irregular breathing
Oculocardiac Reflex
- pressure on eye or traction on surrounding structure–>+para–>bradycardia: atropine
principal determinants of myocardial oxygen demand
- wall tension
- contractility
- heart rate
Predominant autonomic input to hear
parasympathetic via vagus at rest –>normal HR 60-80
Diastolic dysfunction is a major cause of heart failure: true or false?
True. Vernticular stiffening causing impaired ventricular filling is a major cause of heart failure
oculo-cardiac reflex is modulated by which CN
‘Five & dime’: afferent via trigeminal (V) & efferent via vagus (X) causing bradycardia
chief determinants of wall tension
- preload
2. afterload
Major determinant of osmotic pressure In capillary
Plasma proteins
Phase I vs phase II
I: train of four ratio>0.7
II: anticholinesterase drugs–>block
Fade on train of four stimulation
I + II: none has sustained tetanu
High vs low gas flow —> accuracy measuring gas flowing a Thorpe tube w/ a bobbin float
High: turbulence, gas density
Low: laminar, viscosity
A 50 year-old African-American woman has a history of chronic pain that has been stable on multimodal daily pain medication. She presents to the emergency room complaining of vivid dreams and feeling weird, which developed about a day after she started taking Isoniazid for tuberculosis.
Her pain medication regimen likely includes ketamine, and coadministration of isoniazid would likely decrease the metabolism of ketamine as a result of competitive hepatic metabolism. This increased plasma concentration of ketamine could lead to new side effects.
airway nerve innervation
- CN V: mucous membranes of nose: V1 anteriorly (anterior ethmoidal nerve), V2 posteriorly (sphenopalatine nerve); palatine N. (sensory fibers from V): palate; lingual N. (br. of V3): anterior 2/3 tongue
- CN IX (glossopharyngeal): posterior 1/3 tongue, roof of pharynx, tonsil, undersurface of soft palate; easily blocked where it crosses the palatoglossal arch
- Sensation of taste: VII anteriorly, IX posteriorly
- X: sensation bellow epiglottis–>superior laryngeal N–>external br. (motor–cricothyroid muscle) & internal br. (sensory–>larynx between epiglottis & vocal cords, hypopharynx posterior to those structures); recurrent laryngeal N–>sensory: larynx below vocal cords & trachea; motor: all laryngeal muscles except cricothyroid muscle
pharynx extends from base of skull to ?
cricoid cartilage
larynx
- epiglottis - lower end of cricoid cartilages
- 9 cartilages: 3 single (thyroid, cricoid, epiglotic), 3 paired (arytenoid, coniculate, cuneiform)
- cricothyroid membrane: best access–>percutaneous airway
recurrent laryngeal nerve
- Sensation below vocal cord
- all intrinsic muscles of larynx except chricothyroid muscle
- can be damaged during thyroid surgery & by ETT cuff laying just below vocal cord
- block: transtracheal injection via cricothyroid membrane
superior laryngeal nerves
- external branch: motor–>cricothyroid muscle
2. Internal: sensoryminimal; bil–>hoarseness & loss of sensation above vocal cords–>aspiration
Vocal Cord Palsies
- recurrent laryngeal N: unilateral –>hoarseness; bil–>aphonia, stridor, airway obstruction
- vagus N bil injury–>both