Cardiopulmonary resuscitation Study Guide

📖 Core Concepts Cardiopulmonary Resuscitation (CPR) – emergency technique to keep blood‑flowing and oxygenating the brain until a heartbeat returns. CAB sequence – Compression first, then Airway, then Breathing (modern “hands‑only” emphasis). Compression‑to‑ventilation ratios – Adults 30:2, children with 2 rescuers 15:2. Effective compression parameters – Depth ≈ 5 cm (adults/children) / 4 cm (infants); Rate 100–120 /min; full chest recoil between pushes. Defibrillation indication – Shock advised for ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT); not for asystole or PEA. Brain‑time window – Irreversible injury after 7 min of no circulation; most effective CPR started ≤ 6 min. 📌 Must Remember Adult compression depth ≥ 5 cm (≈ 2 in) and rate 100–120 /min. Adult ratio 30 compressions : 2 breaths; child ratio (2 rescuers) 15 : 2. Compression‑only CPR = equal or better outcomes for adult out‑of‑hospital cardiac arrest of cardiac origin. Ventilation‑only is reserved for respiratory arrest with a pulse. AED pad placement – right upper chest & left lateral chest (pediatric pads ≤ 25 kg). Shockable rhythm → defibrillate ASAP; each minute of delay cuts survival 7‑10 %. End‑tidal CO₂ > 20 mm Hg during CPR predicts ROSC. Therapeutic hypothermia target 32‑34 °C for 24 h improves neurologic outcome after ROSC. 🔄 Key Processes Assess safety & responsiveness – tap, shout; if unresponsive, call for help. Check breathing – look for normal breaths; agonal gasps = start CPR. Begin compressions (CAB) Hands‑only: 30 compressions, then 2 breaths if trained. Use a metronome or “Stayin’ Alive” rhythm (≈ 100 bpm). Retrieve AED (as soon as possible) → attach pads, follow prompts. If two rescuers (children): rotate every 2 min to prevent fatigue. Post‑ROSC care – high‑flow oxygen, continuous ECG, consider therapeutic hypothermia. 🔍 Key Comparisons Compression‑Only vs. Standard CPR (adults) – ↔ equal or better survival for cardiac‑origin arrests; ↔ no benefit for asphyxial arrests. Adult vs. Child technique – Adult: two‑hand heel, 5 cm depth; Child: one‑hand (or two if needed) 5 cm depth; Infant: two‑finger 4 cm depth. AED shockable vs. non‑shockable rhythm – VF/VT → shock; Asystole/PEA → continue compressions, treat underlying cause. Layperson vs. Trained rescuer – Layperson: no pulse check, compression‑only; Trained: may assess pulse, incorporate breaths. ⚠️ Common Misunderstandings “Ventilation first” – Modern guidelines prioritize compressions first; delaying compressions reduces survival. “Chest compressions > 120/min are better” – Rates > 120/min impair venous return and lower survival. “All cardiac arrests need breaths” – Adult cardiac‑origin arrests respond well to compression‑only CPR. “AED shocks are dangerous for children” – Use pediatric pads or attenuate energy; defibrillation is lifesaving when indicated. 🧠 Mental Models / Intuition “Pump‑and‑push” – Think of the chest as a pump: push hard, let go fully, then repeat at a steady “beat” (≈ 100 bpm). “Four‑minute clock” – Brain cells start dying at 4 min; every minute of early CPR buys 10 % more chance of survival. “Shock‑or‑no‑shock” – If the AED says “no shock,” keep compressing; the rhythm will self‑correct or remain non‑shockable. 🚩 Exceptions & Edge Cases Traumatic cardiac arrest – CPR may be futile unless reversible cause (tension pneumothorax, tamponade) is treated. Drowning & hypoxia – Simultaneous ventilations with compressions are essential; prioritize breaths. Infants < 1 yr – Use two‑finger compressions, cover mouth & nose for breaths. Patients ≤ 25 kg – Apply pediatric AED pads; otherwise adult pads may deliver excessive energy. 📍 When to Use Which Adult out‑of‑hospital, witnessed, cardiac‑origin → hands‑only CPR + immediate AED. Adult respiratory arrest (pulse present) → ventilation‑focused (assist breaths, monitor pulse). Child or infant cardiac arrest → standard CPR (30:2 or 15:2) with breaths unless cardiac‑origin is certain. Drowning, opioid overdose, asphyxial arrests → compressions + ventilations from the start. 👀 Patterns to Recognize Agonal gasps = “not breathing” → start CPR immediately. Sudden collapse in a public place → high probability of witnessed arrest → prioritize rapid compressions & AED. EMS arrival > 6 min → survival drops sharply; reinforce bystander action early. Shockable rhythm on AED → immediate shock → then resume compressions. 🗂️ Exam Traps Choosing “ventilation first” – Many questions still test the newer CAB order; answer with “compressions first.” Rate > 120/min – Some options list 130/min as “optimal”; correct answer stays within 100‑120/min. Depth of 6 cm for adults – Guidelines specify ≈ 5 cm (2 in); 6 cm is excessive and can cause injury. AED use on infants – If pediatric pads unavailable, adult pads can be used after removing one pad to avoid double energy; not a “no‑shock” scenario. Compression‑only CPR for children – Only correct when the arrest is clearly cardiac; otherwise, standard CPR with breaths is required.