NPLEX II flashcards

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

Cardiac output formula

Cardiac output equals heart rate multiplied by stroke volume. A typical resting adult value is about 5 L/min; increases occur through higher rate, greater contractility, or increased preload.

Mean arterial pressure

Approximated as diastolic pressure plus one third of the pulse pressure. Because most of the cardiac cycle is diastole, MAP reflects organ perfusion better than systolic pressure alone.

Glomerular filtration rate

The volume of plasma filtered per unit time, normally about 125 mL/min. Inulin clearance measures it directly; clinically it is estimated from creatinine, age, sex, and race-free equations.

Renal transport maximum

The saturation point of carrier-mediated tubular reabsorption. Glucose appears in urine once plasma glucose exceeds roughly 180–200 mg/dL, the renal threshold for the sodium-glucose cotransporter.

Anion gap calculation

Sodium minus the sum of chloride and bicarbonate, normally 8–12 mEq/L. Elevated values indicate unmeasured anions such as ketones, lactate, uremic acids, or ingested toxins.

Osmolar gap

Measured osmolality minus calculated osmolality. A gap above 10 mOsm/kg suggests unmeasured solutes such as methanol, ethylene glycol, isopropanol, or mannitol.

Henderson-Hasselbalch equation

pH equals 6.1 plus the log of bicarbonate divided by 0.03 times PaCO2. It links the respiratory component (CO2) and metabolic component (bicarbonate) of acid-base balance.

Competitive inhibition kinetics

The inhibitor competes with substrate at the active site. Km increases because more substrate is needed for half-maximal velocity, while Vmax stays unchanged since inhibition is surmountable.

Noncompetitive inhibition kinetics

The inhibitor binds a site other than the active site, reducing the number of functional enzyme molecules. Vmax falls while Km remains unchanged because remaining enzyme has normal affinity.

Beta-2 receptor effects

Stimulation causes bronchial smooth muscle relaxation and skeletal muscle vasodilation. Beta-2 agonists such as albuterol are used for acute bronchospasm; tremor and tachycardia are common adverse effects.

Alpha-1 receptor effects

Stimulation causes arteriolar and venous constriction, raises blood pressure, contracts the bladder neck and prostate, and dilates the pupil. Alpha-1 blockers treat benign prostatic hyperplasia and hypertension.

Immunoglobulin classes

IgM appears first in infection and fixes complement, IgG dominates secondary responses and crosses the placenta, IgA guards mucosa, IgE drives type I allergy, and IgD sits on naive B cells.

Cardiac action potential plateau

Phase 2 of the ventricular action potential results from slow calcium influx balancing potassium efflux. It prolongs depolarization, allowing calcium entry that triggers contraction.

Resting membrane potential

About −90 mV in cardiac and skeletal muscle, set mainly by potassium permeability and the sodium-potassium pump. Threshold depolarization near −70 mV opens voltage-gated sodium channels.

First-line hypertension therapy

Thiazide diuretics suit most patients; ACE inhibitors or ARBs are preferred with diabetes, proteinuria, or heart failure; calcium channel blockers or thiazides suit older adults. ACE inhibitors are contraindicated in pregnancy.

ST-elevation MI reperfusion

Primary percutaneous coronary intervention is preferred when achievable within 90 minutes of first medical contact; otherwise fibrinolysis is given within 30 minutes of arrival if no contraindication exists.

Diabetes diagnostic thresholds

Diabetes is diagnosed by fasting glucose at least 126 mg/dL, two-hour OGTT at least 200 mg/dL, HbA1c at least 6.5%, or random glucose at least 200 mg/dL with symptoms.

Metformin cautions

Metformin is first-line for type 2 diabetes but is avoided when estimated GFR falls below 30 mL/min/1.73 m2 and held before iodinated contrast because of lactic acidosis risk.

Primary hypothyroidism pattern

High TSH with low free T4 indicates thyroid gland failure. Subclinical disease shows high TSH with normal free T4; central hypothyroidism shows low TSH with low free T4.

Microcytic anemia causes

Low MCV anemias include iron deficiency, thalassemia, lead poisoning, sideroblastic anemia, and anemia of chronic disease. Iron studies and ferritin usually separate the leading causes.

Macrocytic anemia causes

High MCV anemias include vitamin B12 and folate deficiency, alcohol use, hypothyroidism, liver disease, and myelodysplasia. B12 deficiency also causes neurologic deficits and elevated methylmalonic acid.

Bacterial meningitis CSF

Findings include neutrophil-predominant pleocytosis, glucose below 40 mg/dL or a CSF-to-serum ratio under 0.4, and protein above 200 mg/dL. Viral meningitis shows lymphocytes and normal glucose.

Warfarin reversal

Serious bleeding on warfarin is treated with intravenous vitamin K plus four-factor prothrombin complex concentrate. Fresh frozen plasma is an alternative when concentrate is unavailable.

Heparin reversal

Protamine sulfate neutralizes unfractionated heparin, roughly 1 mg per 100 units given in the preceding hours. It partially reverses low-molecular-weight heparin and is not used for fondaparinux.

Asthma versus COPD

Asthma typically begins in childhood with reversible airflow limitation, atopy, and eosinophilia. COPD follows smoking exposure with persistent obstruction, hyperinflation, and reduced diffusing capacity.

Developmental milestones

Head control appears by 4 months, independent sitting by 8 months, walking by 15 months, and two-word phrases by 24 months. Regression of skills requires prompt evaluation.

Acute otitis media criteria

Diagnosis requires middle ear effusion plus acute inflammation, shown by bulging tympanic membrane, new-onset otorrhea, or significant pain. Amoxicillin is first-line for most children.

Community-acquired pneumonia

Typical features include fever, productive cough, tachypnea, and a focal infiltrate on chest imaging. CURB-65 or a pneumonia severity index guides outpatient versus inpatient treatment.

Acute kidney injury staging

KDIGO stages by serum creatinine rise or urine output: stage 1 is 1.5–1.9 times baseline, stage 2 is 2.0–2.9 times, and stage 3 is 3.0 times or dialysis requirement.

Hyperkalemia ECG changes

Progression includes peaked T waves, PR prolongation, loss of P waves, QRS widening, and sine wave pattern. Calcium gluconate stabilizes myocardium; insulin with glucose shifts potassium intracellularly.

Anaphylaxis treatment

Intramuscular epinephrine 0.3–0.5 mg of 1:1000 solution into the lateral thigh is first-line, repeated every 5–15 minutes. Antihistamines and corticosteroids are adjuncts, not initial therapy.

Diabetic ketoacidosis management

Treatment begins with isotonic saline, then intravenous insulin infusion after potassium is above 3.3 mEq/L, with dextrose added once glucose falls near 200 mg/dL to clear ketones.