Look at pressure, blood flow, breathing and the direction of change—before accepting “stable.”
At the bedside, the first question is whether the patient needs immediate treatment. Start with ABCDE and address life-threatening problems as you find them.
Then ask a second question:
Is this patient maintaining normal physiology comfortably, or working hard to compensate?
That distinction helps us recognize danger before the blood pressure falls.
1. Start with the patient, then read the monitor
Before focusing on numbers, watch the patient speak and breathe. Notice their interaction, posture, skin colour and effort.
Can they finish a sentence? Are they newly restless, confused or unusually quiet? Are their hands cold? Do they look more tired than at the last assessment?
Ask the nurse: “What has changed?”
A comfortable appearance is useful information, but it should fit the rest of the assessment.
2. Understand what blood pressure tells you
Blood pressure reflects the interaction between cardiac output and vascular resistance:
MAP − right atrial pressure ≈ cardiac output × systemic vascular resistance
And:
Cardiac output = heart rate × stroke volume
If stroke volume falls, tachycardia and vasoconstriction may help maintain arterial pressure. A normal BP can therefore coexist with impaired circulation. www.resus.org.uk
This is why a faster pulse, cold peripheries and deteriorating interaction deserve attention even when the systolic pressure looks acceptable.
Pressure is part of the assessment of perfusion. It does not measure blood flow directly.
3. Use MAP—but understand its limits
Mean arterial pressure is the average arterial pressure across the cardiac cycle. A familiar approximation is:
MAP ≈ (SBP + 2 × DBP) ÷ 3
For example, a BP of 90/60 mmHg gives an estimated MAP of 70 mmHg. The formula is less reliable with marked tachycardia or irregular rhythms.
MAP helps assess the pressure available to drive organ blood flow. However, flow also depends on vascular resistance and downstream pressure. A congested patient with elevated venous pressure may have an apparently acceptable MAP while organ perfusion remains compromised.
For septic shock, the 2026 Surviving Sepsis Campaign recommends an initial MAP target of 65 mmHg; it conditionally suggests 60–65 mmHg for adults aged 65 or older. These are starting targets for a specific condition, not universal definitions of adequate circulation. SCCM
At the bedside, ask:
“At this pressure, are the patient’s organs showing evidence of adequate perfusion?”
A history of hypertension provides context. It does not automatically mean that every lower reading represents shock or that the patient needs their usual outpatient BP restored.
4. Check perfusion in several places
Perfusion means blood reaching the tissues. Assess it through a combination of findings and their trends.
| Look at | What to assess | Important limitation |
|---|---|---|
| Brain | New confusion, restlessness, drowsiness or slower responses | Consider glucose, medication effects, hypercapnia and neurological disease |
| Skin | Capillary refill, temperature and mottling | Cold surroundings and peripheral vascular disease affect findings; warm skin does not exclude shock |
| Kidneys | Recent urine output and change over time | Oliguria can reflect obstruction or kidney disease as well as impaired circulation |
| Overall course | Whether these findings improve with treatment | One reassuring observation cannot settle the assessment |
Current ESICM guidance supports serial skin-perfusion assessment, including capillary refill, complemented by temperature and mottling. pubmed.ncbi.nlm.nih.gov
In a monitored adult, urine output below approximately 0.5 mL/kg/hour is concerning, but needs context. Do not wait for a prolonged urine-output record before treating obvious deterioration. Resuscitation Council UK
5. Separate oxygen saturation from oxygen delivery
SpO₂ estimates how much of the available haemoglobin is carrying oxygen. It does not tell you how much haemoglobin is present or how much blood reaches the tissues.
Oxygen delivery = cardiac output × arterial oxygen content
Consequently, severe anaemia or low cardiac output can compromise oxygen delivery despite a satisfactory saturation. This follows directly from oxygen-transport physiology. pubmed.ncbi.nlm.nih.gov
The practical questions are:
- Is the blood adequately oxygenated?
- Is there enough haemoglobin to carry oxygen?
- Is circulation delivering it?
A saturation of 98% answers only part of that assessment.
6. Watch how the patient is breathing
Count the respiratory rate when the recorded value seems inconsistent. Assess depth, effort, speech and fatigue.
Rapid, deep breathing may be compensation for metabolic acidosis. Increased effort may reflect respiratory disease. Pain, fever and anxiety can also increase the rate—but should fit the clinical picture.
Pulse oximetry does not measure ventilation or exclude hypercapnia, particularly during supplemental oxygen therapy. www.resus.org.uk
A falling respiratory rate needs interpretation too. If breathing becomes shallow and the patient becomes drowsy, the change may represent exhaustion rather than recovery.
Ask: “Is breathing becoming easier, or is the patient losing the ability to sustain it?”
7. Use tests to clarify the physiology
Choose investigations around the uncertainty you need to resolve.
An ECG identifies the rhythm, but “sinus tachycardia” still needs a cause. Blood gas analysis can clarify acid–base disturbance and ventilation. Haemoglobin helps assess oxygen-carrying capacity.
Lactate can identify risk and help follow response, but it is not a direct measurement of tissue perfusion. Interpret it alongside examination, disease context and other results.
For sepsis, current guidance supports serial lactate assessment when elevated and advises against continuing fluids simply until lactate normalizes. SCCM
Use POCUS to answer focused questions about cardiac function, congestion or a possible obstructive process. ESICM recommends echocardiography as the first imaging approach for identifying the type of shock. A technically limited scan should leave the question open. pubmed.ncbi.nlm.nih.gov
8. Match treatment to the mechanism
Before repeating treatment, reconsider what is failing:
| Suspected mechanism | Direction of treatment |
|---|---|
| Volume loss | Replace the relevant loss and control its source |
| Pump failure | Assess ventricular function and congestion; tailor circulatory support |
| Vasodilation | Treat the cause and support vascular tone when indicated |
| Obstruction | Recognize and relieve the obstruction urgently |
Mixed mechanisms are common.
Persistent tachycardia, oliguria or elevated lactate should not automatically trigger another fluid bolus. After initial resuscitation, assess whether further fluid is likely to increase flow and whether the patient can tolerate it. Dynamic assessment is preferred when applicable. pubmed.ncbi.nlm.nih.gov
Fluid responsiveness means flow may increase with fluid. It does not, by itself, prove that fluid is needed.
9. Reassess the patient and the support required
After an intervention, return to the bedside.
Is interaction better? Is breathing easier? Is peripheral perfusion improving? What happened to heart rate, BP and oxygen requirement?
The same saturation on more oxygen represents a different clinical state. An acceptable BP maintained by increasing vasopressor support also needs a different interpretation.
Make the next review explicit: who, when, what triggers an earlier call, and what happens if treatment fails. Clinical concern can justify escalation even when an early warning score has not increased. www.nice.org.uk
10. Recognize when the next treatment is elsewhere
The ED can assess, resuscitate and begin treatment. Some patients need surgery, intensive care, the cath lab or specialist transfer.
Once that need becomes clear, arrange the destination while continuing stabilization, monitoring and safe handover. Avoid waiting for every number to normalize when definitive treatment is required to improve them.
Before leaving the bedside, ask:
How sick is this patient beyond the numbers?
What dangerous diagnosis could I be missing?
Which direction is the patient moving—and can we provide the next treatment here?
Recognize early. Act early. Reassess often.
References
- Resuscitation Council UK. The ABCDE Approach. Updated July 2024.
- SCCM and ESICM. Surviving Sepsis Campaign: International Guidelines for Management of Sepsis and Septic Shock 2026.
- Monnet X, Messina A, Greco M, et al. ESICM guidelines on circulatory shock and hemodynamic monitoring 2025. Intensive Care Medicine. 2025;51:1971–2012. doi:10.1007/s00134-025-08137-z.
- Oxygen delivery and resuscitation. Physiological background.
- NICE. Acutely ill adults in hospital: recognising and responding to deterioration (CG50).
