Respiratory System - Important Medications and Diseases

Describe how arterial carbon dioxide pressure and bicarbonate determine acid–base status, with thresholds for respiratory and metabolic alkalosis and acidosis, and explain high and normal anion gap metabolic acidosis.

Angiotensin II, formed from angiotensinogen by liver and kidneys and ACE from the lungs, causes vasoconstriction, aldosterone-driven sodium reabsorption, and hypervolemia, raising blood pressure; ACE degrades bradykinin.

Explain how acute high-altitude exposure triggers hyperventilation, respiratory alkalosis, and altitude sickness, then describe chronic adaptations like bicarbonate excretion, acetazolamide use, secondary polycythemia, and increased mitochondrial density.

Explain diffusing capacity for carbon monoxide (dlco) and the dlco ratio to differentiate emphysema, chronic bronchitis, and asthma, and identify restrictive diseases like sarcoidosis, asbestosis, heart failure, scoliosis, and obesity.

Carbon dioxide is transported mainly as bicarbonate via carbonic anhydrase, with 5% dissolved and 5% bound to hemoglobin; chloride exchange and Bohr and Haldane effects operate during lung release.

Describe the normal oxygen–hemoglobin dissociation curve and explain right shifts releasing oxygen in hot, acidic active muscle, left shifts favoring uptake in the lungs, including methemoglobin and carboxyhemoglobin.

Understand the flow-volume loop, distinguishing normal and abnormal patterns; restrictive diseases shift right, COPD shifts left, and airway obstruction keeps the curve central but oval.

Asthma is classified as intermittent, mild, moderate, and severe. Acute exacerbations follow a four-step treatment—salbutamol, prednisolone, bronchodilators, then intubation—driven by blood carbon dioxide levels.

Recognize superior vena cava syndrome as compression of the superior vena cava causing edema of the arms, neck, and head, with headaches or confusion, a medical emergency.

Identify sleep apnea as recurrent loss of breathing during sleep, causing daytime sleepiness. Differentiate obstructive sleep apnea from airway obstruction (obesity) and central sleep apnea from reduced brain respiratory drive.

Pulmonary hypertension is defined as pulmonary pressure above 25, often idiopathic, diagnosed with imaging and right heart catheterization, treated with prostacyclin analogues and lung transplant.

Explore how deep vein thrombosis causes pulmonary embolism, with risk factors and emergency management, including CT angiography and anticoagulation with NOACs, LMWH, warfarin, and Andexanet reversal.

Pleural empyema, a pus-filled infection in the pleural space, resists antibiotics; low glucose and pH with high LDH and protein guide treatment, including drainage when WBC exceeds 50,000.

Assess inhalation burns to gauge prognosis by airway depth using clinical exam and bronchoscopy; treat with prone positioning, bronchodilators, nebulized acetylcysteine, and aerosolized heparin, watching for carbon monoxide poisoning.

Match breathing patterns to clinical scenarios to identify Biot's pattern in brain injury, Cheyne-Stokes in myocardial infarction, tachypnea from airway obstruction, and the rapid, deep breathing of diabetic ketoacidosis.

Explain how emphysema stems from smoking or alpha-1 antitrypsin deficiency and damages alveoli. Describe panacinar or central destruction, barrel chest, lucent lungs, and reduced DLCO with prolonged expiration.

Cystic fibrosis is an autosomal recessive CFTR defect on chromosome 7 causing thick mucus in lungs and pancreas, leading to infections, meconium ileus, infertility, and high sweat chloride.

Identify and compare normal breathing (eupnea) with tachypnea, bradypnea, Biot's, Cheyne-Stokes, and cosmos patterns, and link their causes to brain injury, cardiac damage, and acidotic states.

Grade tumors by differentiation and mitotic activity to assess prognosis, while TNM staging measures size, nodular involvement, and metastasis; C, P, and B denote clinical, pathological, or tumor symptoms.

Tumor lysis syndrome is emergency after chemotherapy, as cancer cells lyse releasing potassium, phosphate, calcium, and uric acid, causing hyperkalemia, hypocalcemia, hyperuricemia, and renal injury; treat with hydration and rasburicase.

Evaluate newly found lung nodules by comparing current chest x-ray with prior images; if inconclusive, CT guides biopsy options or surgical decisions.

Differentiate lung cancers by center versus periphery, highlighting squamous cell carcinoma in smokers. Note peripheral adenocarcinoma with mucus and nail clubbing, and large cell cancer secreting estrogen and beta hCG.

Explain adjuvant, neoadjuvant, salvage, induction, consolidation, and maintenance therapies in cancer treatment, with doxorubicin and cyclophosphamide illustrating additive therapy versus standard therapy and the progressive killing of cancer cells.

Outlines how streptococcus forms chains, produces toxins, evades immunity, and yields pus, causing scarlet fever, toxic shock-like syndrome, rheumatic fever, and glomerulonephritis, with M-protein and erythrogenic toxin as markers.

Staphylococcus aureus is a gram-positive, beta-hemolytic, catalase- and coagulase-positive bacterium with protein A and hemolysin, causing skin infections, pneumonia, endocarditis, MRSA, toxic shock syndrome, scalded skin syndrome, and food poisoning.

Identify respiratory syncytial virus, a seasonal paramyxovirus with enveloped single-stranded RNA, causing upper to lower respiratory symptoms and apnea risk in newborns under two months; palivizumab targets the F protein.

Memorize Pseudomonas aeruginosa features with the Pseudomonas mnemonic, highlighting pneumonia, sepsis, ecthyma gangrenosum, UTIs, osteomyelitis, otitis externa, hot tub folliculitis, and toxins. Treat with antipseudomonal beta-lactams, aminoglycosides, and carbapenems.

Identify neonatal red-eye by onset timing to distinguish Neisseria infection, chlamydia, or viral infection, and apply appropriate treatment plus two drops in each eye containing azithromycin, tetracycline, or silver nitrate.

Nocardia forms long filaments like fungi, is a gram-positive aerobic bacterium found in dirt and soil, causes lung nodules and cough, is acid-fast, PPD negative, may spread to CNS.

Mycoplasma pneumoniae lacks a cell wall and is undetectable by gram stain; cold agglutinin IgM may occur. Cultured on agar, it causes walking pneumonia; treat with macrolides, doxycycline, or fluoroquinolones.

Listeria grows in raw meat and dairy, can cross the placenta. It spreads cell-to-cell using listeriolysin o and actin tails, risking pregnancy and immunocompromised states, and is treated with ampicillin.

Diagnose Legionella by silver stain, charcoal agar culture, or urine antigen; it transmits via water and air, not person-to-person, hyponatremia marks this infection, and treat with macrolides or fluoroquinolones.

Learn about bronchiectasis and infections in cystic fibrosis, including MRSA and pseudomonas, with age-based prevalence around 20 years; treat MRSA with vancomycin and pseudomonas with antipseudomonal penicillins, fluoroquinolones, or linezolid.

Explain how coronavirus, an enveloped pleomorphic virus, enters the respiratory tract via droplets, hijacks host cells to replicate, and triggers inflammation with fever within about 3 or 4 days.

Explore Bordetella pertussis, Parainfluenza, and Haemophilus influenzae with key imaging signs—butterfly chest for pertussis, steeple sign for Parainfluenza, and thumb sign for Haemophilus. Azithromycin treats Bordetella.

Bordetella pertussis, a gram-negative bacterium producing pertussis toxin, causes catarrhal, paroxysmal with whooping and post passive vomiting, and convalescent phases—treat with azithromycin during catarrhal stage and vaccinate to prevent.

Explore how bacillus anthracis is a gram-positive rod that weakens tissues, germinates, releases toxins, and forms spores, causing cutaneous anthrax with a painless eschar and pulmonary anthrax with 100% mortality.

Explore varenicline, a partial nicotine receptor agonist with a long half-life that reduces smoking cravings and withdrawal, and learn about bupropion's dnri role in tobacco cessation and depression.

Vancomycin inhibits peptidoglycan synthesis by binding the d-alanine d-alanine glycoprotein. Targets MRSA, VRE, and C. difficile; red man syndrome and ototoxicity occur, with resistance via alanine-alanine to alanine-lactate.

Treat infections with tetracyclines, including tetracycline, doxycycline, and minocycline, to cover MRSA and pelvic inflammatory disease, by inhibiting bacterial rna binding to ribosomes. Avoid milk, iron, calcium, magnesium with tetracyclines.

Penicillin binds penicillin-binding protein to block peptidoglycan crosslinking and transpeptidase, guiding Pensec indications and prompting beta-lactamase inhibitors like clavulanic acid.

Penicillinase-sensitive penicillins such as amoxicillin and ampicillin, often with beta-lactamase inhibitors, offer broad spectrum; penicillinase-resistant dicloxacillin, nafcillin, and oxacillin treat staph infections (not MRSA) with bile or urine excretion differences.

Metronidazole acts as a free radical generator, delivering antibacterial and antiprotozoal activity against anaerobes and organisms like amoeba, giardia, and h pylori, while risking a disulfiram-like reaction with alcohol.

Inhibits dihydrofolate reductase to block folate synthesis and DNA replication, reducing inflammation in rheumatoid arthritis; leucovorin rescue mitigates myelosuppression and it treats cancers such as acute lymphoid leukemia.

Treat campylobacter, legionella, atypical pneumonia, and pertussis with azithromycin and clarithromycin. Use azithromycin in sexually transmitted diseases; macrolides inhibit ribosomal RNA translocation and resist via RNA methylation.

Explore how folate inhibitors block dna synthesis by inhibiting synthase and reductase, from sulfonamides to trimethoprim, with uses against Nocardia, Salmonella, Pneumocystis jirovecii, toxoplasmosis and leprosy; resistance and adverse effects.

Learn how fluoroquinolones, including moxifloxacin, inhibit DNA gyrase and treat gram-positive and gram-negative infections, including COPD-associated pneumonia. Adverse effects include tendon injuries and GI disturbance; resistance arises from gyrase mutations.

Clindamycin is a bacteriostatic antibiotic that inhibits protein synthesis by targeting the ribosomal subunit and treats anaerobic infections above the diaphragm, but can cause pseudomembranous colitis from Clostridium difficile.

Analyze cephalosporins across five generations, linking gram-positive to gram-negative coverage with agents like cefazolin, ceftriaxone, and cefepime, and review their beta-lactam cell-wall inhibition, blood-brain barrier penetration, excretion, and safety.

Carbapenems kill bacteria by using outer membrane porins to create holes in the cell wall; Ertapenem is especially effective for Pseudomonas.

Describe how beta blockers like propranolol, atenolol, labetalol, and esmolol antagonize beta-1 receptors to slow the heart, aiding in angina, SVT, hypertension, and glaucoma management.

Atropine blocks muscarinic receptors, increasing sympathetic drive to reduce secretions and bladder tone, dilate pupils for eye exams, and treat bradycardia and insecticide poisoning, but causes dry mouth and glaucoma.

Aminoglycosides irreversibly inhibit the 30S subunit, require oxygen for uptake, and treat gram-negative rods with beta-lactams; they cause nephrotoxicity, ototoxicity (deafness in the newborn), and teratogenicity.

Outline adrenergic receptors, including alpha and beta subtypes activated by norepinephrine and epinephrine, and how agonists and antagonists influence vascular tone and smooth muscle for hypertension and asthma.

Assess tuberculosis infection using chest x-ray and sputum analysis, biopsy confirmation, and tuberculin skin test (PPD) with induration thresholds, plus IGRA blood tests; positive results indicate isolation and treatment.

Explore high-yield tb drugs—streptomycin, isoniazid, pyrazinamide, ethambutol, rifamycins—and learn mechanisms like 30S ribosome interference, katG activation, mycolic acid synthesis inhibition, and RNA polymerase inhibition, with key side effects.

ACE inhibitors block ACE, lower angiotensin II, and increase bradykinin to reduce blood pressure and protect kidneys in diabetes; they can cause dry cough and angioedema.

Angiotensin II receptor blockers, or sartan drugs, lower blood pressure with no bradykinin cough. They protect against diabetic nephropathy, may raise creatinine transiently, and cause hyperkalemia and teratogenicity.

Potassium-sparing diuretics, including spironolactone and eplerenone, block sodium channels in collecting ducts to promote diuresis, treating hyperaldosteronism, heart failure, hyperandrogenism, nephrogenic diabetes insipidus, and arthritis, with hyperkalemia risk.

Highlight thiazide diuretics that inhibit sodium chloride reabsorption and calcium excretion in the distal ducts, causing diuresis and hypercalcemia, used for hypertension and heart failure.

Learn how loop diuretics inhibit the sodium potassium two chloride cotransporter in the ascending loop of hennelly to promote diuresis and treat edema, hypertension, and hypercalcemia.

Fludrocortisone is a synthetic aldosterone analogue with glucocorticoid effects, used for primary adrenal insufficiency, causing hypervolemia and edema, and infections via nuclear transcription of anti-inflammatory peptides.

Acetazolamide inhibits renal carbonic anhydrase, depleting bicarbonate and causing metabolic acidosis, alkalizing urine to treat aspirin overdose, altitude sickness, and Pseudotumor Cerebri, with optic nerve fenestration for glaucoma.

Explains the delta, kappa, and mu opioid receptors and how agonism reduces pain mediator release while reviewing major opioids, their receptor actions, uses, withdrawal risks with antagonists, and side effects.

Explain how non-steroidal anti-inflammatory drugs block cyclooxygenase-1 and -2 to reduce prostaglandin synthesis. They relieve pain and fever, affect gastric mucosa protection, PDA status, and renal perfusion.

Aspirin (acetylsalicylic acid) irreversibly inhibits COX-1 at low doses, yielding antiplatelet blood thinning; at high doses it inhibits COX-2 for anti-inflammatory effects, with risks like Reye's syndrome and gastric ulcers.

Explains how acetaminophen inhibits central cyclooxygenase to reduce fever and provide analgesia, with no peripheral anti-inflammatory action, and outlines overdose risks and glutathione-based treatment with NAC or inositol cysteine.

Explore curb 65 criteria for pneumonia admission, including confusion, uremia, respiratory rate, blood pressure, and age, and the corresponding outpatient, inpatient, and icu treatment regimens.

If the tube shifts into a bronchus, the unventilated lung collapses, causing hypoxia; pull the tube back to the common bronchus. If hypoxia persists, consider pneumothorax or atelectasis.