Case 2: 62-year-old woman - Community-Acquired Pneumonia (CAP)

Question 1: Most Likely Diagnosis

• Fever (38.6°C), productive cough with yellow-green sputum, pleuritic right-sided chest pain
• RR 22/min, O2 saturation 92% on room air (hypoxemia)
• WBC 14,500/mm³ with neutrophil predominance (bacterial infection pattern)
• CRP elevated (acute-phase inflammatory marker)
• Chest X-ray: right lower lobe consolidation (hallmark of bacterial lobar pneumonia)
• Crackles on auscultation over the right lower lung field

Question 2: Most Appropriate Initial Empiric Antibiotic Therapy

• Ceftriaxone 1-2g IV daily + Azithromycin 500mg IV/PO daily (beta-lactam + macrolide combination), OR
• Levofloxacin 750mg IV/PO daily (respiratory fluoroquinolone monotherapy)

Question 3: Which CAP Patients Require Hospitalization?

CURB-65 (Goldman-Cecil Medicine, Table 85-4)

• Score 0-1: Outpatient treatment
• Score 2: Consider hospital admission
• Score >2: Hospital admission required; score ≥3 suggests ICU consideration

PSI (Pneumonia Severity Index)

Additional indications for hospitalization:

• O2 saturation <92% or PaO2 <60 mmHg
• Multi-lobe involvement
• Inability to maintain oral intake
• Significant comorbidities (diabetes, immunosuppression)
• Failure of outpatient therapy
• Social factors (inability to care for self at home)

Case 3: Wound

Question 1: Type of Wound

• By cause: Incised, lacerated, contused, abrasion, puncture, burn
• By depth: Superficial (skin only), partial-thickness (dermis), full-thickness (through dermis)
• By contamination: Clean, clean-contaminated, contaminated, dirty/infected
• By duration: Acute vs. chronic

Question 2: Types of Wound Healing

Question 3: Factors that Promote Wound Healing

• Adequate blood supply and tissue oxygenation
• Moist wound environment
• Absence of infection/foreign body
• Proper wound closure and minimal dead space
• Adequate debridement of necrotic tissue

• Good nutrition: Adequate protein (collagen synthesis), vitamin C (hydroxylation of proline/lysine in collagen), zinc (cofactor for enzymes), vitamin A
• Normal tissue perfusion and oxygenation (oxygen is required for collagen cross-linking and bacterial killing)
• Growth factors: PDGF, TGF-beta, EGF, bFGF, VEGF - all drive proliferation, angiogenesis, and matrix synthesis
• Controlled inflammation: Early, acute inflammatory phase is necessary for debridement and signaling
• Youthful age (growth factors more abundant, faster cellular response)
• Normal immune function
• Negative-pressure wound therapy (NPWT) and hyperbaric oxygen therapy (clinical adjuncts)

Question 4: Factors that Delay Wound Healing

• Diabetes mellitus - impairs neutrophil function, reduces growth factors, causes microvascular disease and neuropathy
• Malnutrition - deficiency of protein, vitamin C, zinc
• Advancing age - reduced proliferative capacity
• Obesity - poor tissue perfusion, increased wound tension, adipose tissue has poor blood supply
• Smoking - vasoconstriction, reduced tissue oxygenation, impaired collagen synthesis
• Immunocompromised states (HIV, chemotherapy, steroids) - impaired inflammatory and proliferative response
• Medications: Corticosteroids (suppress inflammation and collagen synthesis), NSAIDs (block thromboxane/prostaglandin signaling), immunosuppressants, chemotherapy agents
• Connective tissue diseases
• Anemia and cardiovascular disease - reduced oxygen delivery

• Infection - prolongs inflammation, destroys new tissue, diverts nutrients
• Ischemia - insufficient oxygen
• Foreign body - perpetuates inflammation
• Excessive wound tension - prevents approximation
• Hematoma/seroma - creates dead space and medium for infection
• Radiation injury - damages microvasculature, fibrosis

Question 5: Phases of Wound Healing

Phase 1 - Hemostasis (immediate, minutes to hours)

• Triggered by vascular injury
• Vasoconstriction followed by vasodilatation and increased permeability
• Platelet activation and aggregation via GPIIb-IIIa, binding to exposed collagen (requires von Willebrand factor)
• Platelet aggregation and fibrin clot formation seals the wound
• Platelets release growth factors: PDGF, TGF-beta, VEGF, EGF - these recruit inflammatory cells
• Goal: stop bleeding, seal wound surface, remove debris and bacteria

Phase 2 - Inflammatory Phase (hours to days 1-5)

• Increased vascular permeability, cellular migration by chemotaxis
• Neutrophils first responders (first 24-48h): phagocytose bacteria, release proteases and reactive oxygen species; primary role is antimicrobial defense
• Macrophages arrive by day 2-3 and are the master regulators: phagocytose debris, release IL-1, IL-6, TNF-alpha, TGF-beta, PDGF, MMPs
• IL-1 enhances collagenase production, stimulates fibroblast and keratinocyte growth
• TNF-alpha initiates the injury response, upregulates adhesion molecules
• Clinically: rubor, calor, dolor, tumor (redness, warmth, pain, swelling)

Phase 3 - Proliferative Phase (days 3-21)

• Angiogenesis: New capillaries form under VEGF stimulation (granulation tissue is highly vascular)
• Fibroplasia: Fibroblasts migrate in and synthesize collagen (initially type III, later replaced by type I) and extracellular matrix
• Wound contraction: Myofibroblasts pull wound edges together centripetally
• Re-epithelialization: Keratinocytes migrate from wound edges and adnexal structures to resurface the wound; driven by EGF, KGF, IFN-kappa
• Granulation tissue (pink, moist, vascular) fills the wound
• ECM components: collagen, fibronectin, glycosaminoglycans (GAGs)

Phase 4 - Maturation/Remodeling Phase (weeks to 1-2 years)

• Begins around week 3 and continues for up to 2 years
• Type III collagen progressively replaced by type I collagen (stronger)
• Collagen fibers are reorganized, cross-linked, and aligned along stress lines
• Wound vascularity decreases (granulation tissue "matures" into scar)
• Maximum tensile strength is ~80% of original skin, reached around 6-12 months
• MMPs degrade ECM and regulate matrix turnover
• Hypertrophic scars or keloids result if remodeling is dysregulated

Key concept: All four phases may occur simultaneously in a large wound. Failure to progress through phases (as in diabetes) leads to chronic non-healing wounds.

Type of Wound: Incised Wound

• Caused by: A sharp-edged object (knife, razor blade, glass shard)
• Edges: Clean, well-defined, regular margins with minimal surrounding tissue damage
• Length > Depth: The wound is longer than it is deep
• Bleeding: Often profuse (sharp cut severs blood vessels cleanly)
• Surrounding tissue: No bruising, crushing, or tearing
• Healing potential: Excellent if sutured promptly - heals by primary intention

How it differs from other wound types:

Management:

Case 2: 50-year-old woman with progressive dyspnea + systemic sclerosis

Question 1: Most Likely Diagnosis

• Progressive exertional dyspnea over 6 months
• Loud P2 (accentuated pulmonic component of S2) = elevated pulmonary artery pressure
• Jugular venous distension + peripheral edema = right heart failure (cor pulmonale)
• Echocardiography: Right ventricular enlargement + estimated pulmonary artery systolic pressure (PASP) 60 mmHg (normal <35 mmHg)
• Background of systemic sclerosis - one of the most common conditions associated with PAH (connective tissue disease is a well-recognized risk factor for Group 1 PAH)
• No chest pain or cough to suggest another etiology

Question 2: Initial Test to Confirm Pulmonary Hypertension

"Right heart catheterization is virtually always required to confirm the diagnosis of pulmonary hypertension, assess its severity, and evaluate ventricular function." - Goldman-Cecil Medicine

"Right heart catheterization is required to confirm the diagnosis of pulmonary hypertension, test for important cardiac causes, and in appropriate patients perform acute vasodilator trials to determine an initial approach to therapy." - Fishman's Pulmonary Diseases

• Mean pulmonary artery pressure (mPAP) ≥ 25 mmHg at rest (updated 2022 threshold: ≥20 mmHg)
• Pulmonary capillary wedge pressure (PCWP) ≤ 15 mmHg (to exclude left heart cause)
• Elevated pulmonary vascular resistance (PVR) > 3 Wood units

• PFTs (spirometry, DLCO - usually reduced in PAH-SSc)
• 6-minute walk test
• NT-proBNP (elevated = marker of RV strain)
• V/Q scan (to rule out chronic thromboembolic disease - Group 4 PH)
• High-resolution CT chest
• ANA, anti-Scl-70, anticentromere antibodies (already known to have SSc)

Question 3: Mainstay of Treatment for Group 1 PAH

Supportive Care (all PAH patients):

• Loop diuretics - reduce pulmonary vascular congestion and RV volume overload
• Supplemental oxygen - attenuates hypoxic pulmonary vasoconstriction
• Digoxin - may improve RV output by ~10% in RV failure
• Supervised exercise/pulmonary rehabilitation - proven benefit
• Vaccinations (influenza, pneumococcal)
• Avoid pregnancy (high maternal mortality)

PAH-Specific Pharmacotherapy (14 FDA-approved agents across 3 pathways):

Current Evidence-Based Strategy:

• AMBITION Trial: Combination of Ambrisentan + Tadalafil showed a 50% reduction in hazard for the composite endpoint (death, hospitalization, disease progression) vs. monotherapy (Braunwald's Heart Disease)
• For NYHA Class IV / cardiogenic shock / syncope / RV ischemia - immediate continuous IV prostacyclin therapy (epoprostenol) is indicated
• For patients with positive acute vasoreactivity test (~5% of iPAH): high-dose calcium channel blockers (nifedipine, diltiazem, amlodipine)

For This Patient (SSc-associated PAH):

• PDE-5 inhibitor (sildenafil or tadalafil) + ERA (ambrisentan or macitentan) is the standard initial combination
• Note: SSc-PAH patients rarely show vasoreactivity, so CCBs are generally not used
• Lung transplantation should be considered if the disease progresses despite maximal medical therapy

Case 3: 50-year-old male - Road Traffic Accident

Question 1: Name of This Sign

Question 2: Diagnosis

"Hemotympanum, mastoid ecchymosis (Battle sign), periorbital ecchymosis ('raccoon eyes'), and CSF otorrhea/rhinorrhea are indicative of a basilar skull fracture." - Washington Manual of Medical Therapeutics

"A fracture of the anterior skull base can result in anosmia, CSF drainage from the nose (rhinorrhea), or periorbital ecchymosis, known as raccoon eyes." - Schwartz's Principles of Surgery

• Battle's sign - bruising over mastoid process (middle fossa fracture)
• Hemotympanum - blood behind tympanic membrane
• CSF rhinorrhea (anterior fossa) or CSF otorrhea (middle fossa)
• Anosmia (olfactory nerve damage)
• CN VII or VIII palsy (petrous temporal bone fracture)

Question 3: Common Types of Skull Fractures

Question 4: Investigations to Confirm the Presence of CSF

Bedside Test:

• A drop of the bloody/clear fluid is placed on filter paper or a bed sheet
• CSF has lower viscosity than blood and migrates faster outward, forming a clear outer ring ("halo") surrounding a central bloody/red spot
• Positive halo = CSF present
• (Rosen's Emergency Medicine)

Laboratory Tests:

Most practical workflow: Halo sign at bedside → beta-2 transferrin to confirm → CT head to identify fracture and complications.

Mitral Valve Prolapse (MVP)

Definition

Etiology & Pathophysiology

Primary MVP (Myxomatous Degeneration)

• The most common form. Leaflets undergo myxomatous degeneration - accumulation of mucopolysaccharides in the spongiosa layer of the valve, leading to leaflet thickening, redundancy, and elongation of chordae tendineae
• Chordae become elongated, slack, or rupture - allowing leaflets to billow back into the LA
• Posterior leaflet is more commonly affected than the anterior
• The mitral annulus is often dilated

Genetics & Associated Conditions

• Can be familial - autosomal dominant with variable penetrance (BMPR2, LMCD1, SPTBN1, TGFB2 gene loci identified)
• Associated with heritable connective tissue disorders:
  • Marfan syndrome (most strongly associated)
  • Ehlers-Danlos syndrome
  • Osteogenesis imperfecta
• Other associations: skeletal deformities (high-arched palate, pectus excavatum, straight back syndrome), Ostium secundum ASD (~20% of cases), inguinal hernias

Secondary MVP

• Seen in: coronary artery disease, rheumatic heart disease, cardiomyopathies, acute rheumatic fever

Pathophysiologic consequences:

• Prolapsing leaflets cause excessive papillary muscle stress → localized ischemia → fibrosis (visible as late gadolinium enhancement on CMR) → nidus for ventricular arrhythmias
• Progressive annular dilation and calcification cause worsening mitral regurgitation (MR)
• Chordae rupture → flail leaflet → sudden severe MR

Epidemiology

• More common in women than men
• Most frequent between ages 15-30 years
• Older men (>50 years) tend to have more severe disease with chordal rupture
• MVP is now the most common cause of isolated severe MR requiring surgery in North America

Clinical Features

Symptoms

• Palpitations (most common - due to ventricular premature contractions, SVT, AF)
• Chest pain - often substernal, prolonged, not exertion-related; rarely resembles angina. May be due to papillary muscle ischemia
• Dizziness, presyncope, syncope - linked to autonomic dysfunction
• Dyspnea and fatigue - if significant MR develops
• Panic attacks - commonly described
• Rarely: transient cerebral ischemic attacks (emboli from mitral valve endothelial disruption)

Physical Examination - Classic Signs:

Dynamic Auscultation - Diagnostic Maneuvers:

Key concept: A smaller LV = more relative redundancy of leaflets and chordae = more prolapse = earlier click.

Investigations

ECG

• Usually normal
• May show: biphasic or inverted T waves in leads II, III, aVF
• Supraventricular or ventricular premature beats

Echocardiography (Diagnostic Gold Standard)

• Diagnostic criterion: Systolic displacement of mitral valve leaflet belly by ≥2 mm into the LA above the mitral annular plane on parasternal long-axis view
• Leaflet thickening ≥5 mm (myxomatous change) = higher risk of complications
• Color Doppler: assess severity of MR (often eccentric jet)
• Identifies flail leaflet, chordal rupture, annular dilation

• Used when more precise anatomic detail is needed
• Mandatory for intraoperative guidance during surgical/transcatheter repair

Transthoracic echo in parasternal long-axis view: both myxomatous leaflets (arrows) billowing into LA in late systole (left); color Doppler showing eccentric MR jet (right). - Harrison's Principles 22nd ed.

Cardiac MRI

• Detects papillary muscle fibrosis (late gadolinium enhancement)
• Precise LV volume assessment
• Identifies mitral annular disjunction

Complications

~10% of patients with thickened leaflets experience serious complications (endocarditis, stroke, severe MR, or sudden death). Men are ~2x more likely to progress to severe MR than women.

Treatment

Asymptomatic MVP (most patients):

• No treatment required
• Infective endocarditis prophylaxis NOT routinely recommended (unless prior history of endocarditis)
• Regular follow-up with echocardiography to monitor MR progression

Symptomatic MVP:

• Beta-blockers - for chest pain, palpitations, and autonomic dysfunction
• Anticoagulation (warfarin/DOAC) - if AF present (guided by CHA2DS2-VASc score); not routinely for MVP alone

Surgical / Interventional Indications (for severe primary MR due to MVP):

• Posterior leaflet prolapse: straightforward repair (resection/plication)
• Anterior/bileaflet prolapse (Barlow's): requires advanced surgical skills

Prognosis

• The vast majority of patients have a benign, lifelong course
• By age 50: ~1 in 200 men require surgery for MR
• By age 70: risk rises to ~3%
• Patients with thickened, redundant leaflets on echo carry higher risk and warrant closer surveillance