Review Session Stars Flashcards
What is the RMP and TP for excitable tissue?
RMP -90mV
TP -60mV
How does hypokalemia affect RMP?
Makes it more negative i.e. hyper-polarizes the cell making it less excitable
How does hyperkalemia affect RMP?
Makes it more positive i.e. Hypopolarizes and tissue is more excitable
Potassium concentration in cardioplegia
15-40 mEq/L
Affect of hypercalcemia on conduction system?
TP becomes less negative (shifts away from RMP) and tissue becomes less excitable
Affect of hypocalcemia on conduction system?
TP becomes more negative (shifts closer tp RMP) and tissue becomes more excitable
Treatment option for hyperkalemia to stabilize membrane?
IV calcium
Free ionized calcium decreases with _________
Alkalosis (More protein bound)
Parathyroidectomy
Major neurotransmitter released from A-delta Fibers
Glutamate
Sensory input from A-Delta Fibers
Fast-Sharp Pain
Glutamate binds to
AMPA & NMDA
The major neurotransmitter released by C-Fibers
Substance-P
Pain from C-Fibers
Slow-Chronic Pain
Substance-P binds to
NK-1 (neurokinin-1)
What are the Ions for each phase of ventricular action potential?
Phase 4: K OUT (leak channels) Phase 0: Na+ INTO Phase 1: Na Closed; Cl IN; K OUT Phase 2: Ca IN Phase 3: K OUT
List the phases of the ventricular action potential?
Depolarization Phase 0 Initial Repolarization Phase 1 Plateau Phase 2 Repolarization Phase 3 Resting Phase 4
What is responsible for establishing RMP in ventricular cells?
K+
What is responsible for absolute refractory period in ventricular cell?
Na+ channels in the inactive state (Phase 1)
Hemodynamic events that accompany acute increase in preload?
Increased EDV (Inc PCWP) Increased SV(PV-Loop wider and taller) No change to ESV BP Increases Baroreceptor decrease in HR and SVR
Hemodynamic events that accompany acute decrease in preload?
Decreased BP (Dec SVR) Decreased ESV & EDV Increased HR (baroreceptor) Increased SV (Dec SVR)
PV-Loop changes for acute decrease in preload?
Shifts DOWN and to the LEFT
i.e. lower pressure smaller volumes
PV-Loop changes for acute Increase in preload?
Shifts to the RIGHT and TALLER
Hemodynamic changes seen with acute increases in contractility?
Increased SV/BP
Decreased ESV/EDV, HR, SVR
What PV-loop changes are seen with acute increases in contractility?
PV-Loop shifts UP and to the LEFT (i.e. digitalis and calcium)
Hemodynamic changes seen with acute decrease in contractility?
Increased ESV/EDV, HR, & SVR
Decrease in SV & BP
What PV-loop changes are seen with acute decrease in contractility?
PV-Loop shifts DOWN and to the RIGHT
Goals in anesthetic management of AS?
Low HR (60-90), SR ( depend one atrial kick), Maintain preload/afterload/contractilty
Most common valvular lesion in the US?
Aortic Stenosis
Hypertrophy seen with AS
Concentric Hypertrophy (Thick walls)
Normal aortic valve area?
2.5-3.5 cm2
Valve area for severe and critical AS
Severe 0.8-1.0 cm2
Critical 0.5-0.8 cm2
Motor innervation of the larynx is via
External SLN to the cricothyroid muscle
RLN to all other
Sensory innervation of the larynx
Internal branch of SLN (From vocal cords upward)
RLN to laryngeal mucosa inferior to the vocal cords
Function of intrinsic muscles of the larynx
Post. crycoarytenoid: Abduct cords (Open)
Lateral Cricoarytenoids : Adduct cords (Close)
Cricothyroid: Tenses Cords (Close/elongate)
Thyroarytenoid: reduce cord tension (relaxes/shorten)
Hypoxia is defined as
PaO2 < 60 mmHg
Things that cause a right shift in the oxyhemoglobin curve
(i.e. Right release) Inc PCO2 Inc temp Inc 2,3-DPG Sickle Cell Decreased pH
Things that cause a left shift in the oxyhemoglobin curve
Fetal hemoglobin Met HgB Carboxy HgB Dec PCO2 Dec Temp Dec 2,3-DPG Dec [H] (inc pH/Alkalosis)
The Bohr effect refers to
the shift in position of the oxyhemoglobin dissociation curve in response to changes in PCO2
What is the affect of hypercarbia on the oxygen dissociation curve? Hypocarbia?
Inc PCO2 will cause a rightward shift.
Dec PCO2 will cause a left shift
Amount of O2 dissolved in blood
0.3 mL O2/100mL (0.003 O2/mL)
What is P50?
The PO2 that produces a 50% saturation of HgB
How do changes in P50 affect the oxyhemoglobin dissociation curve?
- Inc P50 causes a rightward shift
- Dec P50 causes a leftward shift
What is the amount of oxygen carried by each gram of fully saturated hemoglobin?
1.34 mL O2/ g HgB
How to calculate hemoglobin bound to O2?
SpO2 x HgB x 1.34 mL O2/ g HB
Facts for the Dorsal Respiratory Group (DRC)
Maintains basic rhythm of respiration
Inspiratory pacemakers
Located in medulla
Efferent action potentials via phrenic and intercostal nerves (diaphragm & ext. intercostals)
Fact for the Ventral respiratory Group (VRG)
Influence both inspiration and expiration (external intercostals)
Function of the Pneumotaxic Center
Shuts off inspiration (located high in the PONS)
Function of apneustic center
promotes a pattern of breathing of maximal lung inflation with occasional brief expiratory gasps (locates low in the PONS)
Work together to control the rate and depth in inspiration
PnC and ApC
What stimulates the central chemoreceptors?
Respond to Hydrogen Ions
What stimulates peripheral chemoreceptors?
Decreased PaO2**
Increased H ion
Increased PaCO2
__________ carries afferent information from the carotid body chemoreceptors
Glossopharyngeal Nerve
___________ carries afferent information from the aortic bodies and lung stretch receptors
The Vagus Nerve
In what population is the Hering-breur reflex most relevant
Neonates
Purpose of Heiring-breuer reflex
Prevent excess lung inflation
Definition of pKa
The pH at which 50% of a drug is ionized and 50% is non-ionized
When is a weak acid more non-ionized
When pH < pKa
Which form of a drug crosses biological membranes?
non-ionized (aka the weak acid while the ionized form is the conjugate base)
When is a weak base more non-ionized?
pH > pKa
pKa of lidocaine
7.7 (7.9)
Examples of drugs that are weak bases include
ketamine, opioids, and benzos
Mnemonic for rate of systematic absorption
I (IV) Think (Tracheal) I (Intercostal) Can (caudal) Push (paracervical) Each (epidural) Bolus (Brachial Plexus) SSlowly (subarachnoid/sciatic) For (femoral) Safety (sub-Q)
IV > Tracheal > Intercostal > Caudal > Paracervical > Epidural > Brachial Plexus > Subarachnoid/Sciatic > Femoral > Sub-Q
Order of nerve fiber blockade after epidural
B > C/Adelta > Agamma > Abeta > Aalpha
Roots blocked by the cervical Plexus block
C2-C4
Volume of LA for cervical Plexus block
3-5 mL per level
Cervical plexus block is used for what surgeries
Lymph Node dissection
Plastic repairs
CAE
Fluid maintenance for infants < 6 months
4 mL/kg for 1st 10 kg
2 mL/kg for next 10 kg (up to 20kg)
1 mL/kg over 20 kg
Fluid maintenance for infants and children > 6 months
10-40 mL/kg over 1-4 hours
Components of fetal circulation
RA to LA via PFO
PA to Aorta via ductus arteriosus
Associated anomalies for trisomy 21
SUBGLOTTIC STENOSIS: Also Congenital heart dz, Recurrent pulm infection, RTracheoesophageal fistula (TEF), Seizures, Floppy soft palate, Bowel atresia, Enlarged tonsils, OSA, Macroglossia, ASD/VSD, Endocardial cushion defect, PDA, TOF
What causes increased Work of Breathing in the geriatric population?
Skeletal calcification, increased airway resistance
What is the most common postoperative complication in older adults?
Post-operative Delirium
Postoperative delirium is characterized by
Disruption of perception, phsychomotor behavior, consciousness, thinking’s/memory, sleep-wake cycle, and attention
Risk factors for postoperative delirium
Older age, male, dementia, hx of EtOH, depression, duration of anesthesia, poor functional status, abn. electrolytes and glucose, parkinsons, CV disease, dehydration, metabolic dz, anticholinergic drugs used intraoperatively, patient admission to ICU, type of sx
In what procedures is post-operative delirium most common?
Ortho procedures, patients undergoing cardiac surgery
Define apnea
Airflow cessation greater than 10 seconds, >= 5x per hour in combination with a 4% decrease in arterial O2 saturation
Define OSA
A cessation of breathing for periods longer than 10 seconds during sleep.
- Includes apnea and hypopnea
Risk factors for OSA in obese patients
Male,
Middle age,
BMI > 30,
Evening EtOH consumption
What is the hallmark of OSA
Snoring, daytime symptoms of sleepiness, impaired concentration, memory problems, & morning headaches
Definitive diagnosis of OSA
polysomnography
What is pickwickian syndrome
a complication of extreme obesity, characterized by OSA, hypercapnea, daytime hypersomnolence, arterial hypoxemia, cyanosis-induced polycythemia, respiratory acidosis, pulmonary hypertension, and right-sided failure.
Define central apnea
apnea without respiratory effort. ( seen in OHS)
OHS is defined as
- BMI>30 kg/m2
- Daytime hypoventilation with awake PCO2 > 45 mmHg
- Sleep disordered breathing in the absence of other causes of hypoventilation.
Formula for IBW
Female= Height (cm) - 105 Male= Height (cm) - 100
How does CO change in obese patients
increased by 20-30 mL/kg of excess body fat
What is metabolic syndrome?
A constellation of metabolic abnormalities including abdominal obesity, glucose intolerance, HTN, and dyslipidemia.
Metabolic syndrome is associated with an increased risk of
Vascular events
Diagnosis of metabolic syndrome
At least 3 of the following:
- Central (android) obesity; i.e. waist circumference . 102cm in males or >88 cm in females
- Elevated serum triglycerides: >= 150 mg/dL
- Reduced serum HDL: men <= 40 mg/dL; women <= 50 mg/dL
- HTN: >130/85 mmHg, or taking antihypertensive medication
- Elevated fasting serum glucose >= 100 mg/dL
the most common mononeuropathy after bariatric surgery
Carpal Tunnel Syndrome
Affect of supine position in obese patient
ventilatory impairment: decreased FRC and oxygenation
Provides the longest safe apnea period during induction of anesthesia in an obese patient
Head-Up Position
