A realistic handwritten medical exam answer sheet on ruled white paper, written in blue ballpoint pen in neat student handwriting. The page shows: At the top center, underlined heading: "OXYGEN THERAPY" Below in smaller underlined text: "Indications, Modes and Complications" A horizontal line beneath. Section heading (underlined, bold-style): "INTRODUCTION" Paragraph text: "Oxygen therapy refers to the administration of oxygen at concentrations greater than 21% (atmospheric O₂) to treat or prevent hypoxia. O₂ is a drug with specific indications, dosing and adverse effects." Section heading (underlined): "A. INDICATIONS OF OXYGEN THERAPY" "1. PRIMARY INDICATION:" " → Arterial hypoxemia: PaO₂ < 60 mmHg OR SaO₂ < 90%" " → Tissue hypoxia (regardless of PaO₂)" "2. SPECIFIC CLINICAL CONDITIONS:" " a) Respiratory failure – Type I (hypoxic) and Type II (hypercapnic)" " b) Shock states – hypovolemic, septic, cardiogenic, obstructive" " c) Cardiac arrest – 100% O₂ immediately" " d) Carbon monoxide poisoning – 100% O₂ reduces COHb half-life" " from 4–5 hrs (room air) → ~1 hour" " e) Severe anaemia – to maximize saturation of available Hb" " f) Acute MI – only if SpO₂ < 90%, heart failure or shock present" " (NB: Routine O₂ in MI increases infarct size – avoid if normoxic)" " g) Post-operative recovery – prevent atelectasis" " h) Cluster headache – 100% O₂ is first-line abortive therapy" " i) High altitude sickness (AMS/HACE/HAPE)" " j) Cyanide poisoning, Pneumonia, Pulmonary embolism" "3. CAUTION (not absolute contraindication):" " • COPD with chronic CO₂ retention – give controlled O₂ (SpO₂ 88–92%)" " • Paraquat poisoning – O₂ worsens pulmonary toxicity" Small asterisk note at bottom: "* Never withhold O₂ from a truly hypoxic patient fearing complications" The handwriting is clean, uses underlining for headings, arrows and bullet points, slight variation in letter size as natural handwriting would appear. Lined paper background visible. Page number "1" at bottom right.

A realistic handwritten medical exam answer sheet on ruled white paper, written in blue ballpoint pen in neat student handwriting. The page shows: Top: underlined heading "B. MODES OF OXYGEN THERAPY (Delivery Devices)" A horizontal line beneath. "Classified into: (i) Low-flow systems (ii) High-flow systems (iii) Reservoir systems" Subheading underlined: "I. LOW-FLOW SYSTEMS (variable FiO₂ – depends on tidal volume)" "1. Nasal Cannula (Nasal Prongs)" " • Flow rate: 1–6 L/min" " • FiO₂: ~24–44% (each 1 L/min adds ~4% FiO₂)" " • Comfortable, allows eating/talking" " • HFNC (High Flow Nasal Cannula): up to 60 L/min, FiO₂ up to 100%" "2. Simple Face Mask" " • Flow rate: 5–10 L/min" " • FiO₂: ~35–55%" " • Minimum 5 L/min to flush CO₂ from mask" "3. Partial Non-Rebreather Mask" " • Has reservoir bag – one-way valve missing between bag and mask" " • Flow rate: 10–12 L/min → FiO₂: ~60–80%" "4. Non-Rebreather Mask (NRM)" " • Reservoir bag + two one-way valves" " • Prevents rebreathing of exhaled air" " • Flow rate: 15 L/min → FiO₂: ~70–90%" " • Used in: CO poisoning, severe hypoxia" Subheading underlined: "II. HIGH-FLOW SYSTEMS (fixed FiO₂ – accurate, reliable)" "5. Venturi Mask (Air-entrainment mask)" " • Most accurate O₂ delivery" " • Colour-coded adapters:" " Blue = 24% White = 28% Yellow = 35%" " Red = 40% Green = 60%" " • BEST for COPD patients – precise low-flow O₂" Subheading underlined: "III. INVASIVE / ADVANCED MODES" "6. CPAP/BiPAP (NIV) – adds positive pressure support" "7. Mechanical Ventilation (intubation) – FiO₂ 21–100% titrated" "8. Hyperbaric O₂ Therapy (HBO) – 100% O₂ at >1 atm pressure" " Indications: decompression sickness, CO poisoning, gas gangrene" "9. O₂ Tent / Incubator (paediatrics/neonates)" A small hand-drawn table with 3 columns labeled Device | Flow (L/min) | FiO₂ (%) with 4 rows of data filled in with numbers. Page number "2" at bottom right.

A realistic handwritten medical exam answer sheet on ruled white paper, written in blue ballpoint pen in neat student handwriting. The page shows: Top: underlined heading "C. COMPLICATIONS OF OXYGEN THERAPY" A horizontal line beneath. Subheading underlined: "I. OXYGEN TOXICITY (most important complication)" "Mechanism: Excess O₂ → formation of Reactive Oxygen Species (ROS)" " → superoxide, hydroxyl radicals, hydrogen peroxide" " → lipid peroxidation of cell membranes → cell death" "A. Pulmonary Oxygen Toxicity:" " Stage 1 – Tracheobronchitis (within 6–24 hrs of 100% O₂)" " Sx: substernal chest pain, cough, dyspnoea" " Stage 2 – ARDS-like picture (after 24–48 hrs)" " Diffuse alveolar damage, protein-rich exudate, decreased compliance" " Threshold: FiO₂ > 0.6 for > 24 hours → significant risk" " FiO₂ < 0.5 is considered safe" "B. Retinopathy of Prematurity (ROP):" " Premature neonates (<32 wks) – hyperoxia → vasoconstriction" " → retinal neovascularization → retinal detachment → blindness" " Target SpO₂ in preterm: 91–95%" Subheading underlined: "II. HYPERCAPNIA / CO₂ RETENTION" "Mainly in COPD patients (chronic hypercapnia)" "Mechanisms:" " a) Haldane Effect: O₂ displaces CO₂ from Hb → ↑ dissolved CO₂" " b) ↓ Hypoxic drive: removes the hypoxic ventilatory stimulus" " c) V/Q mismatch worsening: O₂ reverses hypoxic vasoconstriction" " → blood flow to poorly ventilated alveoli → CO₂ rises" "Result: Respiratory acidosis, narcosis, coma" "Prevention: Controlled O₂ therapy (target SpO₂ 88–92% in COPD)" Subheading underlined: "III. ABSORPTION ATELECTASIS" "High FiO₂ replaces N₂ (which normally 'splints' alveoli open)" "O₂ is rapidly absorbed → alveolar collapse → atelectasis" "Especially in regions with low V/Q ratio" Page number "3" at bottom right. Handwriting is clean, uses underlining for headings, arrows, bullet points, with natural handwriting variation.

A realistic handwritten medical exam answer sheet on ruled white paper, written in blue ballpoint pen in neat student handwriting. The page shows: At top: underlined heading "COMPLICATIONS (continued) + MONITORING + CONCLUSION" A horizontal line beneath. Subheading underlined: "IV. OTHER COMPLICATIONS" "4. Fire hazard / Combustion risk" " O₂ supports combustion – patient must not smoke" " Serious burns possible (esp. with nasal cannula use)" "5. Drying of mucous membranes" " Unhumidified O₂ at high flow rates → nasal dryness, crusting" " Prevention: humidification at flow > 4 L/min" "6. Infection risk" " From O₂ delivery equipment (masks, tubing, humidifiers)" " Regular change of equipment necessary" "7. Suppression of erythropoiesis" " Long-term hyperoxia → reduced EPO → ↓ RBC production" "8. Hyperbaric O₂ specific complications:" " • Barotrauma (ear, sinus)" " • Central nervous system (CNS) O₂ toxicity" " (Paul Bert effect) – convulsions, seizures at pO₂ > 1.6 atm" " • Claustrophobia" Subheading underlined: "D. MONITORING OF OXYGEN THERAPY" " • Pulse oximetry (SpO₂) – continuous, non-invasive" " • ABG (Arterial Blood Gas) – gold standard" " – PaO₂, PaCO₂, pH, HCO₃⁻" " • SpO₂ targets:" " General patients: 94–98%" " COPD / type II RF: 88–92%" " Preterm neonates: 91–95%" Subheading underlined: "CONCLUSION" "Oxygen therapy is life-saving when used correctly. The key principles are:" " 1. Treat hypoxia promptly – never withhold O₂ from a hypoxic patient" " 2. Use lowest effective FiO₂ to achieve target SpO₂" " 3. FiO₂ < 0.5 is safe long-term; above 0.6 risks toxicity" " 4. Controlled therapy in COPD to prevent CO₂ narcosis" " 5. Monitor continuously – ABG + SpO₂" At the very bottom a small diagram showing a simple oxygen delivery device spectrum from left to right: "Room Air (21%) → Nasal prongs → Simple mask → NRM → Venturi → Mechanical ventilation (100%)" with an arrow pointing right labelled "Increasing FiO₂" Page number "4" at bottom right.