Critical care: Admission and organ support

• Critical care basics: Levels of Care and Critical Care Services | Referral and Admission Decisions | Severity Scores | Monitoring in Critical Care | Blood Gas Interpretation
• Respiratory support: Respiratory Failure | High-flow Oxygen, CPAP and NIV | Invasive Mechanical Ventilation | ARDS | Weaning and Tracheostomy
• Other organ support: Cardiovascular Support — Vasopressors and Inotropes | Renal Replacement Therapy | Sedation, Analgesia and Neuromuscular Blockade | Nutrition and Glucose Control | ECMO and Transfer of the Critically Ill
• Revision: Organ Support at a Glance | Spot the Diagnosis | Exam-style Scenarios | Key Points | Guidelines and Further Reading

🫀 Critical care — admission and organ support — page 4 of the Anaesthetics and Critical Care chapter. Intensive care supports failing organs while the underlying illness is treated or recovers. It is a bridge, not a cure — so deciding who will benefit, recognising deterioration early and knowing what each form of support can and can't do are core skills for every acute physician and surgeon. (Shock and sepsis are covered in the Acute Medicine chapter.)
Your four questions for every critically ill patient: Which organs are failing — and how badly? Is the cause reversible, and will critical care benefit this patient (what would they want)? What support do they need now — oxygen, ventilation, vasopressors, renal replacement? What could go wrong next, and how will I know?

Levels of Care and Critical Care Services

• Levels of care (Intensive Care Society 2021):

  Level	Needs	Where and staffing
  0	Normal ward care	Ward
  1	At risk of deterioration, or recently stepped down; more frequent observations, outreach input	Ward (with outreach)
  1 enhanced	Enhanced care — e.g. high-risk postoperative monitoring	Enhanced perioperative care units
  2	Single organ support (e.g. NIV, single vasopressor, invasive monitoring) or step-down from level 3	HDU — nurse:patient about 1:2
  3	Advanced respiratory support (invasive ventilation) alone, or support of two or more organs	ICU — nurse:patient 1:1

• Critical care outreach teams — respond to deteriorating ward patients (NEWS2 triggers), support wards and follow up patients after ICU discharge.
• Critical care networks — regional networks coordinate capacity, transfers and specialist care (e.g. ECMO, neurosurgery, burns).
• Specialist units — cardiothoracic, neurosciences, liver, burns, paediatric (PICU) and neonatal (NICU).
• The ICU multidisciplinary team — intensivists, nurses, physiotherapists, dietitians, pharmacists, speech and language therapists, occupational therapists, psychologists, microbiologists.
• GPICS (Guidelines for the Provision of Intensive Care Services) — UK standards — consultant review within 12 hours of admission, twice-daily ward rounds, consultant to patient ratio, rehabilitation.

Referral and Admission Decisions

• When to refer — early, when a patient is deteriorating despite ward treatment: NEWS2 of 7 or more, airway compromise, falling GCS, respiratory failure (rising oxygen need, rising CO₂), shock not responding to fluid, lactate over 4, severe metabolic derangement, need for organ support; and after high-risk surgery.
• SBAR — Situation, Background, Assessment, Recommendation — structure for the referral.
• Deciding on admission — a shared, senior decision balancing:
  • Reversibility of the acute illness.
  • Baseline health — comorbidities, frailty (Clinical Frailty Scale — CFS 5 or more is associated with poorer outcomes, but frailty alone shouldn't decide), functional status.
  • The patient's wishes and values — advance decisions, ReSPECT forms, LPA, discussion with family.
  • Likely outcome — survival and quality of life after ICU (not "can we keep them alive" but "will this help them get back to a life they value?").
• Treatment escalation plans (TEPs) and ReSPECT — document early what treatments are appropriate (ward-based care, NIV ceiling, ICU, CPR) — ideally with the patient.
• Time-limited trials — admit for a defined period of organ support with clear goals; review and withdraw if not improving.
• If ICU isn't appropriate — ward-based maximal treatment with a ceiling, or palliative care — explain to patient and family; ensure symptom control.
• Capacity and disputes — best interests (Mental Capacity Act 2005), second opinions, mediation, ethics committee, courts as a last resort.

Severity Scores

• Purpose — describe severity, compare units (case mix adjustment), research — not to decide treatment for individual patients.
• APACHE II (Acute Physiology and Chronic Health Evaluation) — worst physiological values in the first 24 hours (temperature, MAP, heart rate, RR, oxygenation, pH, sodium, potassium, creatinine, haematocrit, WCC, GCS), age and chronic health — 0–71; predicts hospital mortality.
• SOFA (Sequential Organ Failure Assessment) — scores 6 organ systems (0–4 each):
  • Respiratory — PaO₂/FiO₂ ratio.
  • Coagulation — platelets.
  • Liver — bilirubin.
  • Cardiovascular — MAP and vasopressor dose.
  • CNS — GCS.
  • Renal — creatinine or urine output.
  — a rise of 2 or more points with infection defines sepsis (Sepsis-3); serial SOFA tracks progress.
• qSOFA — RR 22 or more, altered mentation, systolic BP 100 or less — bedside prognostic tool (not for diagnosis; NEWS2 is used in the UK).
• ICNARC model — UK risk model used for national audit (Case Mix Programme).
• SAPS, MODS — other systems; Clinical Frailty Scale — baseline frailty.
• Organ-specific scores — GCS, Child–Pugh and MELD (liver), CURB-65 (pneumonia), KDIGO (AKI), Murray score (lung injury — ECMO referral).

Monitoring in Critical Care

• Basic — continuous ECG, SpO₂, RR, temperature, hourly urine output (catheter), fluid balance, GCS and pupils, capillary glucose.
• Arterial line — beat-to-beat BP (MAP target usually 65 mmHg or more), frequent blood gases; the waveform's variation with ventilation (pulse pressure variation) suggests fluid responsiveness.
• Central venous catheter — vasopressors, irritant drugs, TPN; CVP (poor guide to fluid responsiveness on its own); ScvO₂ (central venous oxygen saturation — low under 70% suggests inadequate oxygen delivery).
• Cardiac output monitoring — pulse contour analysis (LiDCO, PiCCO), oesophageal Doppler, echocardiography (bedside focused echo — LV and RV function, tamponade, filling); pulmonary artery catheter (rare now).
• Fluid responsiveness — passive leg raise (about 300 mL "autotransfusion" — rise in stroke volume of 10% or more suggests responsiveness), fluid challenge with stroke volume measurement, pulse pressure variation (ventilated, sinus rhythm).
• Lactate — marker of tissue hypoperfusion (and other causes — adrenaline, liver failure, metformin, seizures); trend matters (lactate clearance).
• Neurological monitoring — ICP monitoring (traumatic brain injury), EEG (non-convulsive status), pupillometry, transcranial Doppler.
• Point-of-care ultrasound — lungs (B-lines, effusions, pneumothorax), heart, abdomen, vessels (DVT), line insertion.
• Daily checks — "FAST HUGS BID" — Feeding, Analgesia, Sedation, Thromboprophylaxis, Head-up position, Ulcer prophylaxis, Glucose control, Spontaneous breathing trial, Bowels, Indwelling catheters (lines — remove if not needed), De-escalation of antibiotics.

Blood Gas Interpretation

• Normal values (arterial) — pH 7.35–7.45; PaO₂ 10–13 kPa on air; PaCO₂ 4.7–6.0 kPa; HCO₃^– 22–26 mmol/L; base excess –2 to +2; lactate under 2 mmol/L.
• Step-by-step:
  • 1. Oxygenation — is PaO₂ appropriate for the FiO₂? (PaO₂ should be about 10 kPa less than the inspired % — e.g. FiO₂ 40% → PaO₂ about 30 kPa); P/F ratio (PaO₂ in kPa ÷ FiO₂ as a fraction — normal over 53 kPa (400 mmHg)).
  • 2. pH — acidaemia or alkalaemia?
  • 3. Primary process — CO₂ (respiratory) or HCO₃^–/base excess (metabolic)?
  • 4. Compensation — respiratory compensation for metabolic problems is fast (minutes); renal compensation takes days (chronic respiratory acidosis has a high bicarbonate); compensation never overcorrects.
  • 5. Anion gap in metabolic acidosis — (Na⁺ + K⁺) – (Cl^– + HCO₃^–) — normal about 10–18 (or 8–12 without potassium); correct for low albumin.
• Causes:

  Disorder	Causes
  Raised anion gap metabolic acidosis	Lactate (shock, sepsis, ischaemia), ketones (DKA, alcohol, starvation), renal failure, toxins (methanol, ethylene glycol, salicylates, metformin, paracetamol — pyroglutamic acid)
  Normal anion gap (hyperchloraemic)	Diarrhoea, ileostomy, large-volume 0.9% saline, renal tubular acidosis, Addison's, acetazolamide, ureteric diversion
  Metabolic alkalosis	Vomiting and NG losses, diuretics, hypokalaemia, Conn's and Cushing's, post-hypercapnia
  Respiratory acidosis	COPD, opioids and sedatives, neuromuscular weakness (GBS, MG), chest wall disease, obesity hypoventilation, exhaustion (asthma)
  Respiratory alkalosis	Anxiety, pain, hypoxia (PE, pneumonia, altitude), early salicylate toxicity, pregnancy, liver failure, sepsis

• Type 1 respiratory failure — PaO₂ under 8 kPa with normal or low CO₂; type 2 — PaO₂ under 8 kPa with PaCO₂ over 6.0 kPa.
• Venous gas — pH, bicarbonate, lactate, potassium and glucose are close to arterial values; not reliable for oxygen (and CO₂ only to screen — a normal venous CO₂ excludes arterial hypercapnia).

Respiratory Failure

• Type 1 (hypoxaemic) — V/Q mismatch or shunt — pneumonia, pulmonary oedema, ARDS, PE, pulmonary fibrosis, atelectasis, COVID-19.
• Type 2 (hypercapnic) — ventilatory failure:
  • Reduced drive — opioids, sedatives, head injury, stroke, hypothyroidism.
  • Neuromuscular — Guillain–Barré syndrome, myasthenia gravis, motor neurone disease, high spinal cord injury, critical illness weakness.
  • Chest wall and pleura — kyphoscoliosis, obesity hypoventilation, flail chest.
  • Airways and lungs — COPD, severe asthma (exhaustion), bronchiectasis.
• Clinical features — breathlessness, tachypnoea, accessory muscles, inability to speak, cyanosis, tachycardia, confusion or drowsiness (hypercapnia — flapping tremor, bounding pulse, headache), paradoxical breathing, exhaustion.
• Neuromuscular respiratory failure — monitor forced vital capacity (FVC) — under 20 mL/kg (or falling quickly, or under 1 L) — consider ICU; intubate at about 15 mL/kg ("20/30/40 rule" — FVC under 20 mL/kg, maximum inspiratory pressure weaker than –30 cmH₂O, maximum expiratory pressure under 40 cmH₂O); SpO₂ and gases fall late; bulbar weakness (aspiration risk).
• Escalation — controlled oxygen → high-flow nasal oxygen or CPAP (type 1) or NIV (type 2) → invasive ventilation; set the ceiling of care early.

High-flow Oxygen, CPAP and NIV

• NIV in COPD (BTS 2016) — start within 60 minutes of the blood gas showing respiratory acidosis that persists despite treatment; decide the ceiling of care before starting (would intubation be appropriate if NIV fails?); NIV reduces mortality and intubation.
• Contraindications to NIV — undrained pneumothorax (relative — drain first), facial trauma or burns, upper airway obstruction, vomiting, recent upper GI surgery, inability to protect the airway (very low GCS — though hypercapnic coma may respond), copious secretions, haemodynamic instability, patient refusal.
• Signs of NIV failure — worsening pH and CO₂ after 1–4 hours, falling GCS, exhaustion, inability to tolerate — escalate to intubation (if appropriate) or palliation.
• Complications — mask leak, pressure sores on the nose (dressings), gastric distension, aspiration, dry eyes, claustrophobia, pneumothorax, hypotension.
• Delayed intubation — prolonged HFNO or NIV in failing patients may increase mortality — have a clear plan and review frequently.

Invasive Mechanical Ventilation

• Indications — airway protection (GCS 8 or less, bulbar failure), respiratory failure not responding to non-invasive support, exhaustion, need for deep sedation or paralysis (agitation, ICP control, procedures), cardiovascular collapse, transfer.
• Modes:
  • Volume control — set tidal volume and rate; airway pressure varies (watch peak and plateau pressures).
  • Pressure control — set inspiratory pressure and rate; tidal volume varies with lung compliance.
  • SIMV and assist-control — mandatory breaths with patient-triggered breaths.
  • Pressure support (spontaneous mode — "CPAP/PS") — patient triggers every breath; ventilator adds pressure — used in weaning.
  • Others — BiLevel/APRV, neurally adjusted (NAVA).
• Key settings — FiO₂, PEEP (positive end-expiratory pressure — keeps alveoli open, improves oxygenation; can reduce venous return and BP), tidal volume, rate, inspiratory:expiratory (I:E) ratio (usually 1:2; prolonged expiration in asthma and COPD), trigger sensitivity.
• Improving oxygenation — raise FiO₂ and PEEP (and mean airway pressure), recruitment, prone positioning.
• Improving CO₂ clearance — raise minute ventilation (rate or tidal volume) — but accept "permissive hypercapnia" (pH over 7.2) in lung-protective ventilation.
• Complications of ventilation:
  • Ventilator-induced lung injury — volutrauma, barotrauma (pneumothorax), atelectrauma, biotrauma.
  • Ventilator-associated pneumonia (VAP) — prevention bundle: head of bed 30–45°, daily sedation holds and spontaneous breathing trials, subglottic secretion drainage, oral care (chlorhexidine use now debated), cuff pressure checks, avoid unnecessary reintubation.
  • Haemodynamic — reduced venous return and cardiac output (hypotension after intubation).
  • Dynamic hyperinflation (breath stacking — auto-PEEP) in asthma and COPD — hypotension, high pressures — disconnect from the ventilator briefly, slow rate, longer expiration.
  • Tube complications (displacement, blockage), sedation complications, ICU-acquired weakness, delirium, stress ulcers, VTE.

ARDS

• Acute respiratory distress syndrome — acute, diffuse, inflammatory lung injury with increased capillary permeability, non-cardiogenic pulmonary oedema and severe hypoxaemia.
• Berlin definition (2012):
  • Onset within 1 week of a known insult or new or worsening respiratory symptoms.
  • Bilateral opacities on chest X-ray or CT, not fully explained by effusions, collapse or nodules.
  • Respiratory failure not fully explained by cardiac failure or fluid overload (echo if no risk factor).
  • Oxygenation (with PEEP or CPAP 5 cmH₂O or more) — P/F ratio mild 200–300 mmHg (26.7–40 kPa), moderate 100–200 mmHg (13.3–26.7 kPa), severe 100 mmHg or less (13.3 kPa or less).
  • (A 2023 global definition extends this to patients on high-flow oxygen and uses SpO₂/FiO₂ where gases aren't available.)
• Causes — direct (pneumonia — commonest, aspiration, inhalation injury, near drowning, lung contusion, COVID-19) and indirect (sepsis, pancreatitis, major trauma, massive transfusion, TRALI, burns, drugs).
• Management (FICM/ICS guideline 2018):
  • Treat the cause (antibiotics, source control).
  • Lung-protective ventilation — tidal volume 6 mL/kg predicted (ideal) body weight, plateau pressure under 30 cmH₂O, appropriate PEEP, accept permissive hypercapnia (ARDSNet).
  • Prone positioning for at least 12–16 hours a day in moderate to severe ARDS (P/F under 150 mmHg — 20 kPa) — reduces mortality (PROSEVA).
  • Conservative fluid strategy once shock has resolved.
  • Neuromuscular blockade — consider early, short-term in severe ARDS (evidence mixed).
  • Steroids — for some (e.g. COVID-19 — dexamethasone; early severe ARDS — evidence evolving).
  • ECMO (VV-ECMO) — for severe refractory ARDS in selected patients — referral to a commissioned centre.
  • Not recommended — routine high-frequency oscillation, routine inhaled nitric oxide (rescue only).
• Outcome — mortality about 30–40%; survivors may have long-term breathlessness, weakness and psychological problems.

💡 Clinical Pearl: Calculate tidal volume from predicted body weight (based on height and sex), not actual weight. A short, obese woman ventilated at "6 mL/kg" of actual weight may be receiving double the lung-protective volume.

Weaning and Tracheostomy

• Readiness to wean — improving underlying cause, adequate oxygenation (FiO₂ 0.4 or less, PEEP 5–8 or less), haemodynamically stable (minimal vasopressors), awake and cooperative (daily sedation hold), adequate cough and secretion clearance, normal electrolytes (potassium, magnesium, phosphate).
• Spontaneous breathing trial (SBT) — 30–120 minutes on low pressure support or a T-piece — success if breathing is comfortable, RR and heart rate stable, oxygenation maintained.
• Rapid shallow breathing index (RR ÷ tidal volume in litres) — under 105 suggests a successful wean.
• Extubation — after a successful SBT, with a plan; high-flow oxygen or NIV after extubation in high-risk patients (reduces reintubation); assess for post-extubation stridor (cuff leak test; steroids if high risk).
• Failed weaning — causes: unresolved illness, fluid overload, cardiac dysfunction, ICU-acquired weakness, diaphragm dysfunction, delirium, malnutrition, electrolyte disturbance, anxiety.
• Tracheostomy:
  • Indications — prolonged ventilation or weaning (often after 7–14 days), inability to protect the airway or clear secretions (neurological injury, bulbar weakness), upper airway obstruction.
  • Advantages — less sedation, more comfort, easier mouth care, communication (speaking valve), mobilisation, reduced dead space.
  • Percutaneous (bedside, in ICU) or surgical.
  • Complications — bleeding, displacement, blockage (secretions), infection, pneumothorax, tracheal stenosis, tracheo-innominate fistula (late massive bleeding).
• Tracheostomy and laryngectomy emergencies (National Tracheostomy Safety Project) — know whether the patient has a patent upper airway (tracheostomy) or not (laryngectomy — neck breather only); bedhead signs; emergency algorithm — call for help, oxygen to face and stoma, remove speaking valve and inner tube, pass a suction catheter, deflate the cuff, remove the tube if blocked; oxygenate via the stoma (laryngectomy) or orally (tracheostomy).

Cardiovascular Support — Vasopressors and Inotropes

• Aim — restore tissue perfusion — usually MAP 65 mmHg or more (higher in chronic hypertension; lower targets — 60–65 — in older people may be acceptable — 65 trial), adequate urine output, falling lactate, improving mental state and skin perfusion.
• Fluids first — in hypovolaemia and sepsis (assess fluid responsiveness); avoid fluid overload.
• Vasoactive drugs:

  Drug	Receptors	Main effects and uses
  Noradrenaline	Mainly α1 (some β1)	Vasoconstriction — raises SVR and MAP — first-line vasopressor in septic shock
  Vasopressin	V1 receptors	Vasoconstriction — second-line added to noradrenaline in septic shock (noradrenaline-sparing)
  Adrenaline	α and β (β at low doses)	Inotrope and vasopressor — anaphylaxis, cardiac arrest, refractory shock; raises lactate and glucose; arrhythmias
  Dobutamine	Mainly β1 (some β2)	Inotrope — cardiogenic shock and sepsis with poor cardiac function; can drop BP (vasodilatation)
  Milrinone	Phosphodiesterase-3 inhibitor	Inodilator — heart failure, right ventricular failure, after cardiac surgery; hypotension
  Levosimendan	Calcium sensitiser	Inotrope — acute heart failure (specialist)
  Metaraminol, phenylephrine	α1	Short-term peripheral vasopressors (theatre, ED, before central access)
  Dopamine	Dose-dependent D1, β1, α	Rarely used now (arrhythmias); "renal dose" dopamine doesn't protect kidneys

• Administration — central venous catheter preferred (extravasation causes tissue necrosis); peripheral noradrenaline at low concentrations is increasingly used short term via a large, well-functioning cannula; arterial line for monitoring.
• Hydrocortisone — in septic shock needing ongoing vasopressors (e.g. 200 mg a day) — speeds shock reversal (ADRENAL, APROCCHSS).
• Mechanical support (cardiogenic shock — specialist centres) — intra-aortic balloon pump (no mortality benefit in AMI shock — IABP-SHOCK II), Impella, VA-ECMO.
• Classifying shock — hypovolaemic, distributive (sepsis, anaphylaxis, neurogenic), cardiogenic, obstructive (PE, tamponade, tension pneumothorax) — see Acute Medicine chapter.

Renal Replacement Therapy

• AKI in critical care — common (up to half of ICU patients) — sepsis, hypotension, nephrotoxins, contrast, rhabdomyolysis, abdominal compartment syndrome; associated with higher mortality.
• Indications for renal replacement therapy (RRT) — "AEIOU":
  • Acidosis — severe metabolic acidosis (pH under 7.15) not responding to treatment.
  • Electrolytes — refractory hyperkalaemia (over 6.5 mmol/L or with ECG changes despite treatment).
  • Intoxication — dialysable toxins (lithium, methanol, ethylene glycol, salicylates, metformin-associated lactic acidosis, valproate).
  • Overload — fluid overload (pulmonary oedema) not responding to diuretics.
  • Uraemia — complications (pericarditis, encephalopathy, bleeding).
• Timing — early "pre-emptive" RRT has no clear benefit over a watchful strategy without urgent indications (STARRT-AKI, AKIKI).
• Modes:
  • Continuous RRT (CRRT) — haemofiltration (CVVH — convection), haemodialysis (CVVHD — diffusion) or both (CVVHDF) — gentler on haemodynamics — standard in UK ICUs.
  • Intermittent haemodialysis — faster solute removal (toxins, severe hyperkalaemia) — needs stable BP.
  • Peritoneal dialysis — rarely used in adult ICU.
• Practicalities — large-bore dual-lumen vascath (internal jugular or femoral), anticoagulation of the circuit (citrate — regional; or heparin), dose about 20–25 mL/kg/hour effluent.
• Complications — hypotension, electrolyte shifts (hypophosphataemia, hypokalaemia, hypocalcaemia — citrate accumulation in liver failure), bleeding, line infection and thrombosis, hypothermia, drug removal (adjust antibiotic doses).
• Recovery — most ICU survivors with AKI recover renal function, but there is an increased risk of CKD — follow-up of renal function after discharge.

Sedation, Analgesia and Neuromuscular Blockade

• Principle — "analgesia first" (analgosedation), then the lightest sedation that keeps the patient safe and comfortable.
• Sedation scoring — RASS (Richmond Agitation–Sedation Scale — +4 combative to –5 unrousable); target usually 0 to –2 (calm, alert or lightly sedated) unless deep sedation is needed (raised ICP, severe ARDS, paralysis, status epilepticus).
• Drugs:
  • Propofol — short-acting, easy to titrate; hypotension; propofol infusion syndrome (high doses over 4 mg/kg/hour for over 48 hours); calories (lipid).
  • Opioids — fentanyl, alfentanil, remifentanil, morphine (accumulates in AKI).
  • Alpha-2 agonists — dexmedetomidine and clonidine — light sedation, helpful in agitation and alcohol withdrawal; bradycardia and hypotension.
  • Benzodiazepines (midazolam) — accumulate and increase delirium — avoid as routine sedation (except seizures, alcohol withdrawal, deep sedation needs).
  • Ketamine — adjunct for analgesia and in asthma.
• Daily sedation interruption ("sedation hold") with spontaneous breathing trials — shorter ventilation and ICU stay.
• Neuromuscular blockade — for intubation, severe ARDS (short term), ICP control, therapeutic hypothermia (shivering), ventilator dyssynchrony; requires deep sedation (awareness risk — BIS monitoring); contributes to ICU-acquired weakness.
• ABCDEF bundle (ICU liberation) — Assess, prevent and manage pain; Both spontaneous awakening and breathing trials; Choice of analgesia and sedation; Delirium — assess, prevent, manage (CAM-ICU); Early mobility and exercise; Family engagement.

Nutrition and Glucose Control

• Critical illness is catabolic — rapid muscle loss (up to 2% a day in the first week); malnutrition worsens outcomes.
• Enteral nutrition first — start early (within 24–48 hours) once haemodynamically stable — nasogastric tube; maintains gut integrity; trophic feeding at first, building up over days; avoid overfeeding in the first week.
• NG tube position — confirm with aspirate pH 5.5 or less or chest X-ray before first use (misplaced NG tube feeding is a never event).
• Parenteral nutrition (PN) — if enteral feeding is impossible or inadequate (gut failure, obstruction, high-output fistula) — central line (or PICC); risks — line sepsis, hyperglycaemia, liver dysfunction, refeeding.
• Requirements — energy about 20–25 kcal/kg/day initially (indirect calorimetry if available), protein 1.2–2 g/kg/day; remember calories from propofol.
• Refeeding syndrome — after starvation, alcohol excess or low BMI — hypophosphataemia, hypokalaemia, hypomagnesaemia, thiamine deficiency, fluid overload, arrhythmias — start feeding slowly (10 kcal/kg/day in high risk), check and replace electrolytes, thiamine before feeding (NICE CG32).
• Stress ulcer prophylaxis — PPI or H2 antagonist for high-risk patients (mechanical ventilation with coagulopathy, shock) — reassess daily (risk of pneumonia and C. difficile).
• Glucose control — stress hyperglycaemia is common; target 6–10 mmol/L (avoid tight control — 4.5–6.0 increased mortality in NICE-SUGAR) with insulin infusion; avoid hypoglycaemia.
• Bowel care — constipation (opioids) and diarrhoea (feeds, antibiotics, C. difficile) — bowel protocol.

ECMO and Transfer of the Critically Ill

• ECMO (extracorporeal membrane oxygenation):
  • VV-ECMO (veno-venous) — blood drained from a large vein, oxygenated and CO₂ removed, returned to a vein — respiratory support for severe, potentially reversible respiratory failure (ARDS, COVID-19, status asthmaticus) — e.g. Murray score 3 or more, or pH under 7.20 from uncompensated hypercapnia.
  • VA-ECMO (veno-arterial) — returns blood to an artery — cardiac and respiratory support — cardiogenic shock, refractory cardiac arrest (ECPR), massive PE, hypothermia rewarming.
  • Complications — bleeding (systemic anticoagulation), thrombosis, limb ischaemia, infection, stroke, haemolysis.
  • Provided by a small number of commissioned adult respiratory ECMO centres in England — referral by the treating ICU; mobile ECMO retrieval teams.
• Transfers of critically ill patients — intrahospital (CT, theatre) or interhospital (specialist care, capacity):
  • Indication and risk–benefit — "stabilise before transfer" (but some — e.g. extradural haematoma, ruptured AAA — need transfer as part of resuscitation).
  • Secure the airway before transfer if there's any doubt (intubate rather than risk deterioration on the road).
  • Equipment — transport ventilator, monitoring (ECG, SpO₂, invasive BP, capnography), enough oxygen (calculate — plus a reserve), suction, drugs, infusions on battery syringe drivers, defibrillator.
  • Personnel — a trained doctor (airway skills) and a trained nurse or practitioner; communication with the receiving unit (handover — SBAR, ABCDE), documentation, notes and imaging.
  • Physiology of transport — acceleration and deceleration (hypotension), vibration, temperature, noise, altitude (air transfer — gas expansion — drain pneumothoraces).
  • Use checklists (Intensive Care Society transfer guidance 2019; FICM/ICS); regional adult critical care transfer services in England.

Organ Support at a Glance