Why this matters: Critical care is the organised support of patients with actual or threatened failure of one or more organs. EMTs and emergency nurses do not need to wait for an ICU bed to think critically: early recognition, ABCDE, trend monitoring, infection prevention, communication and timely escalation improve survival in every setting.
Scope: This guide supports learning and does not replace local critical-care protocols, senior review or specialist decisions. Use the WHO/ICRC Basic Emergency Care approach and facility escalation pathways, and adapt interventions to available equipment and staffing.
Learning outcomes
- Explain how critical illness causes organ dysfunction and why trends matter.
- Use ABCDE, SAMPLE and early warning scores to identify deterioration.
- Monitor respiratory, cardiovascular, neurological, renal, metabolic and temperature status.
- Describe common organ-support principles: oxygen/ventilation, fluids/vasopressors, renal support and nutrition.
- Apply infection prevention, medication safety, pressure injury prevention and human-factors principles.
- Communicate escalation, referrals, family updates and end-of-life concerns professionally.
1. What makes a patient critically ill?
Critical illness is a rapidly changing state in which the body cannot maintain oxygen delivery, perfusion, ventilation, neurological function or metabolic balance without support. Causes include sepsis, trauma, burns, respiratory failure, poisoning, cardiac arrest, severe obstetric emergencies and postoperative complications. A patient may compensate for a time and then deteriorate rapidly; repeated observation is therefore essential.
| Organ system | Failure clues | Immediate questions |
|---|---|---|
| Airway/lungs | Stridor, exhaustion, cyanosis, rising CO2, low SpO2, silent chest. | Is the airway open? Is oxygen reaching the blood? Is ventilation adequate? |
| Circulation | Hypotension, weak pulse, cold skin, delayed capillary refill, oliguria, rising lactate. | Is there bleeding, sepsis, pump failure, obstruction or dehydration? |
| Brain | New confusion, agitation, reduced GCS, seizures, unequal pupils. | Glucose? Oxygen/CO2? Stroke, trauma, infection, toxins or hypoperfusion? |
| Kidneys/metabolism | Low urine, rising creatinine, potassium/pH abnormalities, acidosis. | Perfusion, nephrotoxins, obstruction, fluid balance and dialysis needs? |
| Skin/temperature | Mottling, fever/hypothermia, rash, burns, pressure injury. | Infection, exposure, shock, drug reaction or heat/cold injury? |
2. ABCDE and the first hour
- A — Airway: assess voice, obstruction, secretions and protection; suction, position and call airway help.
- B — Breathing: rate, effort, chest movement, SpO2, ETCO2/ABG, oxygen/ventilation support and treat reversible causes.
- C — Circulation: pulse/BP/perfusion, ECG, bleeding control, IV/IO access, fluids/blood/vasopressor pathway and lactate.
- D — Disability: GCS/AVPU, pupils, glucose, seizures, temperature and neurological trend.
- E — Exposure: inspect skin, wounds, abdomen, back, lines, urine, pressure areas and environmental hazards while preventing heat loss.
Resuscitation and diagnosis run together. Treat a life threat immediately, but keep asking why the patient is deteriorating: sepsis, bleeding, obstruction, toxicity, endocrine crisis, cardiac disease or trauma may coexist.
3. Monitoring in critical care
| Domain | Core observations | Trend that demands escalation |
|---|---|---|
| Respiratory | RR, work of breathing, SpO2, oxygen device, ETCO2, ABG, breath sounds. | Increasing oxygen/ventilatory support, fatigue, rising CO2, silent chest or falling SpO2. |
| Cardiovascular | HR/rhythm, BP/MAP, capillary refill, skin, lactate, urine output. | Persistent hypotension, new arrhythmia, cold/mottled skin, rising lactate or escalating vasopressor. |
| Neurological | GCS/AVPU, pupils, pain/sedation score, seizures, delirium. | Falling consciousness, new focal deficit, unequal pupils, refractory agitation or seizures. |
| Renal/fluid | Hourly urine where indicated, fluid input/output, weight, creatinine/electrolytes. | Oliguria/anuria, pulmonary oedema, severe electrolyte/pH change. |
| Infection | Temperature, cultures, source, WBC/markers, lines/wounds. | New fever/hypothermia, shock, worsening organ function or line infection. |
4. Respiratory and cardiovascular support
| Support | Principles | Safety checks |
|---|---|---|
| Oxygen | Treat hypoxaemia and titrate to a target; reassess work of breathing and cause. | Correct device/flow, cylinder supply, humidification and SpO2 limitations. |
| NIV | Selected cooperative patients with respiratory failure; allows spontaneous breathing. | Airway protection, mask fit, aspiration risk, CO2/ABG, haemodynamics and escalation plan. |
| Invasive ventilation | Airway protection or failure of oxygenation/ventilation; use lung-protective strategy. | Tube/capnography, pressures, alarms, sedation/analgesia, infection prevention and backup BVM. |
| Fluids | Restore perfusion when hypovolaemia is likely; reassess after each bolus. | Overload harms lungs/heart/kidneys; consider bleeding, sepsis, cardiogenic and obstructive shock. |
| Vasopressors/inotropes | Support vascular tone or cardiac output when fluids alone are inadequate. | Infusion pump, dedicated line, extravasation precautions, ECG/BP and perfusion trend. |
5. Shock and perfusion
| Shock type | Typical clues | First priorities |
|---|---|---|
| Hypovolaemic | Bleeding/dehydration, tachycardia, cool skin, narrow pulse pressure. | Control source, access, blood/fluids, keep warm and reassess response. |
| Distributive/septic | Infection, fever/hypothermia, warm or mottled skin, vasodilation, lactate. | Early recognition, cultures/antibiotics pathway, fluids/vasopressor support and source control. |
| Cardiogenic | Chest pain, pulmonary oedema, raised JVP, cool skin, arrhythmia. | ECG/reperfusion pathway, cautious fluids, inotrope/vasopressor and critical-care review. |
| Obstructive | Tension pneumothorax, tamponade, massive PE; sudden collapse/PEA. | Relieve the obstruction by trained clinicians; avoid delaying for routine tests. |
| Anaphylactic | Airway/breathing/circulation compromise with possible hives/angioedema. | IM adrenaline first-line, oxygen/airway, fluids and observation for recurrence. |
6. Renal, metabolic and nutritional support
- Measure urine output, fluid balance, electrolytes, glucose, lactate and acid–base status; trends often reveal deterioration before creatinine changes.
- Review nephrotoxic medicines and contrast exposure; adjust doses with pharmacy/renal advice.
- Recognise hyperkalaemia, severe acidosis, hypoglycaemia, DKA, hyperthermia, hypothermia and refeeding risk.
- Start appropriate nutrition when stable; enteral feeding is often preferred when the gut works, with aspiration and glucose monitoring.
- Dialysis/renal replacement decisions require critical-care/nephrology teams; prepare access, haemodynamic support and infection precautions.
7. Delirium, pain and sedation
| Intervention | Good practice |
|---|---|
| Pain | Ask/observe, treat underlying cause, use multimodal analgesia and reassess respiratory/hemodynamic effects. |
| Sedation | Set a target, use the lightest effective level, review daily and avoid masking neurological deterioration. |
| Delirium | Look for hypoxia, infection, pain, retention, constipation, withdrawal, drugs, sleep deprivation and metabolic disease. |
| Communication | Reorientate, explain procedures, involve family/support, use glasses/hearing aids and preserve day/night cues. |
8. Infection prevention and device safety
- Perform hand hygiene before and after every patient/device contact; gloves never replace hand hygiene.
- Use aseptic technique for IV/IO, urinary, airway and central-line care; review daily whether each device remains necessary.
- Maintain ventilator bundles: head elevation where appropriate, oral care, suction, circuit hygiene and early weaning assessment.
- Inspect lines, drains, wounds and pressure points every shift; label infusions and trace every tube from patient to source.
- Isolate suspected communicable infection, use PPE, dispose of sharps safely and communicate exposure risks during transfer.
9. Medication and infusion safety
| Risk | Prevention |
|---|---|
| High-alert infusions | Standard concentrations, smart pumps where available, independent double-check and dedicated lines. |
| Look-alike/sound-alike drugs | Read labels three times, separate storage and verbal read-back. |
| Line confusion | Trace from pump to patient, label every lumen/tubing and never assume colour means drug. |
| Transitions of care | Reconcile medicines, last dose, infusion rate, allergies, renal/hepatic function and monitoring plan. |
| Extravasation | Inspect site, stop infusion without flushing, follow drug-specific protocol and notify senior staff. |
10. Pressure injury, mobility and thrombosis prevention
- Assess risk, reposition according to condition, protect heels/sacrum/occiput and keep skin clean/dry.
- Provide passive/active range-of-motion and early mobilisation with lines/airway secured.
- Use venous-thromboembolism prophylaxis when prescribed; balance bleeding/trauma risk.
- Maintain nutrition, hydration, temperature and continence care; treat pain before movement.
- Use safe manual handling and adequate staff—never pull a ventilated patient by tubes or lines.
11. Human factors and escalation
- Use structured handover (SBAR/ATMIST) and state the urgent concern at the beginning.
- Escalate based on trend, not a single “normal” value; a rising RR or oxygen requirement may precede hypotension.
- Use checklists for airway, transfer, line insertion, medication and resuscitation.
- Invite the team to speak up about a safety concern; confirm orders with closed-loop communication.
- After a critical event, debrief, document, report near misses and support staff wellbeing.
12. Communication, consent and family-centred care
- Explain what is known, what is uncertain and what is being done next using plain language.
- Check decision-making capacity; involve a surrogate only when appropriate and document who was consulted.
- Respect culture, language, privacy, spiritual needs and the patient’s advance wishes.
- Protect confidentiality while sharing information needed for safe care.
- When prognosis is poor, senior clinicians should lead honest goals-of-care discussions and symptom-focused care; EMTs provide compassionate support and accurate observations.
13. Transfer to ICU or higher-level care
| Before leaving | During transfer | On arrival |
|---|---|---|
| Stabilise ABCDE as far as possible, secure airway/lines, prepare oxygen/medicines, verify destination and document. | Continuous monitor, trained escort, backup BVM/oxygen/suction, battery and communication. | Structured handover, repeat vitals/ABG, reconcile infusions and confirm responsibility. |
| Bring imaging, labs, medication chart, allergies, consent and contact details. | Anticipate deterioration from movement, disconnection, pain or temperature loss. | Trace every device, confirm ventilator/infusion settings and document time of transfer. |
14. Critical-care scenarios
Scenario 1 — Sepsis trend: A patient’s RR rises from 24 to 34, SpO2 needs increase, urine falls and lactate rises while BP remains “normal.” Escalate now; trend deterioration can precede shock.
Scenario 2 — Ventilated hypotension: A patient becomes hypotensive after PEEP is increased. Assess preload, right-heart function, pneumothorax, bleeding, sedation and sepsis; involve critical care rather than changing settings alone.
Scenario 3 — Delirium: An ICU patient pulls at lines and becomes confused at night. Check oxygenation, glucose, pain, infection, retention, withdrawal and medicines; use reorientation and the least restrictive safety plan.
Scenario 4 — Transfer risk: During movement to CT, the oxygen cylinder empties and the ventilator alarms. Stop, manually ventilate, call for help and use the backup plan. A transport checklist should have prevented this.
Scenario 5 — AKI: Urine output falls, potassium rises and the patient develops weakness/ECG changes. Escalate urgently, stop nephrotoxins, obtain access and follow hyperkalaemia/renal-replacement protocols.
15. Daily critical-care checklist
- Airway/device position, oxygen/ventilation settings, ABG/ETCO2 and weaning readiness.
- Circulation: rhythm, BP/perfusion, lactate, access, fluids, vasopressors and bleeding.
- Neurology: GCS/pupils, pain, sedation target, delirium, seizures and communication.
- Renal/metabolic: urine, fluid balance, electrolytes, glucose, nutrition and medication doses.
- Infection: cultures/antibiotics, temperature, lines, wounds and device necessity.
- Mobility/skin: pressure areas, turning, physiotherapy, VTE prophylaxis and safe handling.
- Family/goals: updates, consent, escalation ceiling, resuscitation status and discharge/transfer plan.
16. Revision questions
- Why does a rising respiratory rate matter even when BP is normal?
- How can positive-pressure ventilation cause hypotension?
- List five causes of new ICU delirium.
- What steps reduce ventilator-associated infection?
- What should be checked before transporting a ventilated patient to CT?
- How do trend monitoring and early warning scores support escalation?
- What details belong in a critical-care handover?
- Why is a medication/infusion double-check essential for high-alert drugs?
- How can EMTs support family-centred care and confidentiality?
- What features suggest the need for renal/critical-care review?
17. Key take-home points
- Critical care is a system of early recognition, organ support, monitoring, infection prevention and teamwork.
- ABCDE is repeated after every intervention and whenever the patient or trend changes.
- Trend respiratory effort, perfusion, urine, mental state and oxygen requirement—not isolated “normal” values.
- Prevent harm from lines, ventilators, medicines, pressure, immobility and communication failures.
- Safe transfers require preparation, backup equipment, trained escort and structured handover.
Selected authoritative resources
- WHO Emergency Care Toolkit.
- WHO/ICRC Basic Emergency Care course.
- WHO infection prevention and control resources.
- WHO clinical management of sepsis.
For EMT practice: A critically ill patient needs a reliable team, not just a high-technology bed. Recognise early, support the failing organ, prevent avoidable harm and communicate every change.