CRNA (NCE) flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

MAC of isoflurane

Isoflurane MAC in adults is approximately 1.15% at 1 atm; MAC decreases about 6% per decade after age 40 and is lower with hypothermia, pregnancy, and opioid coadministration.

Meyer-Overton correlation

Anesthetic potency correlates directly with lipid solubility: agents with higher lipid solubility have lower MAC values, supporting a membrane lipid-based mechanism of action.

Succinylcholine phase I block

Depolarizing block produces decreased twitch height without fade or post-tetanic facilitation, and it is not reversed by anticholinesterases; recovery requires metabolism by plasma pseudocholinesterase.

Hepatic clearance formula

Clearance equals the product of hepatic blood flow and extraction ratio (Cl = Q x ER); agents with high extraction are flow-limited, while low-extraction drugs are capacity-limited.

Law of Laplace in alveoli

Alveolar wall tension (P = 2T/r) means smaller alveoli require higher pressure to remain open, a tendency offset by surfactant lowering surface tension.

Resting membrane potential

The resting potential of about -70 mV results mainly from potassium permeability; hypokalemia hyperpolarizes the cell and can reduce excitability, while hyperkalemia depolarizes it.

E cylinder oxygen volume

A full E cylinder holds about 660 L at 1900 psi; volume remaining equals gauge pressure in psi multiplied by 0.28 L/psi.

Pin Index Safety System

Cylinder yokes use two pins matched to specific gas cylinders to prevent misconnection; oxygen uses pins 2 and 5 on the valve stem.

Desflurane vaporizer design

Desflurane requires a heated, pressurized vaporizer (about 39 C, near 2 atm) because its high vapor pressure at room temperature would otherwise make a variable-bypass vaporizer inaccurate.

Soda lime CO2 absorption

About 100 g of soda lime absorbs roughly 26 L of carbon dioxide; exhaustion is signaled by color change and rising inspired carbon dioxide concentration.

Pulse oximeter wavelengths

Pulse oximetry compares absorption of 660 nm red and 940 nm infrared light to estimate oxyhemoglobin fraction; it is unreliable with methemoglobin, carboxyhemoglobin, and poor perfusion.

Rapid sequence induction

Rapid sequence induction combines preoxygenation, a rapidly acting induction agent, and succinylcholine 1-1.5 mg/kg with cricoid pressure to secure the airway and limit aspiration risk.

Tetanic stimulation fade

Fade during tetanic stimulation at 50-100 Hz reflects presynaptic depletion of acetylcholine and is characteristic of nondepolarizing neuromuscular blockade.

Train-of-four ratio 0.9

A train-of-four ratio of at least 0.9 at the adductor pollicis indicates adequate recovery from neuromuscular blockade, reducing residual weakness and postoperative pulmonary complications.

Malignant hyperthermia treatment

Stop triggering agents, hyperventilate with 100% oxygen, give dantrolene 2.5 mg/kg repeated as needed, and cool the patient while treating hyperkalemia and acidosis.

MAC-BAR

The concentration that blocks autonomic responses to a nociceptive stimulus, typically about 1.3-1.5 times MAC and higher than MAC-awake.

Propofol induction dose

Propofol 1.5-2.5 mg/kg IV produces hypnosis in 30-60 seconds; it causes hypotension through vasodilation and myocardial depression and has antiemetic properties.

Hyperbaric spinal solution

Hyperbaric bupivacaine contains dextrose, making it denser than cerebrospinal fluid so it settles with gravity; patient position after injection determines the spread of the block.

Lipid emulsion for LAST

For local anesthetic systemic toxicity, give 20% lipid emulsion 1.5 mL/kg bolus followed by 0.25 mL/kg/min infusion while supporting airway and circulation and treating seizures.

Dermatome of the umbilicus

The umbilicus corresponds to the T10 dermatome; nipple is T4, xiphoid T7, inguinal ligament L1, and the perineum S2-S4.

Interscalene block complication

Interscalene brachial plexus block frequently causes ipsilateral phrenic nerve paresis and Horner syndrome; it is avoided in patients with severe contralateral pulmonary disease.

Maximum lidocaine dose

Lidocaine without epinephrine is limited to about 4.5 mg/kg (300 mg) and with epinephrine about 7 mg/kg (500 mg) to reduce systemic toxicity risk.

Uncuffed ETT size formula

Uncuffed tracheal tube internal diameter in millimeters equals age in years divided by 4, plus 4; cuffed tubes are typically half a size smaller.

Left uterine displacement

After 20 weeks of gestation, tilt the patient or displace the uterus leftward to relieve aortocaval compression, which otherwise reduces venous return and cardiac output.

Pediatric sevoflurane MAC

Sevoflurane MAC peaks near 3.2% in infants aged 1-6 months and decreases with age; infants also have higher oxygen consumption and faster desaturation.

Cerebral perfusion pressure formula

Cerebral perfusion pressure equals mean arterial pressure minus intracranial pressure; in neuroanesthesia, targets usually keep CPP between 60 and 70 mmHg.

One-lung ventilation hypoxemia

If saturation falls during one-lung ventilation, apply CPAP to the non-dependent lung and PEEP to the dependent lung, and recheck tube position with bronchoscopy.

ASA physical status III

ASA III denotes severe systemic disease that is not incapacitating, for example poorly controlled diabetes, stable angina, or end-stage renal disease on dialysis.

Four elements of negligence

A malpractice claim requires duty owed to the patient, breach of that duty, injury, and a causal link between the breach and the injury.

Surgical safety time-out

Before incision, the team confirms patient identity, procedure, site, allergies, consent, antibiotic timing, and equipment availability as part of the universal protocol.

Airway fire sequence

On airway fire, stop all gases, remove the tracheal tube, flood the field with saline, ventilate with air once the fire is out, then reassess the airway by bronchoscopy.

SBAR handoff

SBAR structures handoff communication as Situation, Background, Assessment, and Recommendation, reducing omissions during transfer of anesthesia care.