Oscillometric versus femoral intra-arterial blood pressure in prehospital critical care
Date First Published:
August 27, 2026
Last Updated:
August 27, 2026
Report by:
Simon Carley, Consultant (Manchester NHS Foundation Trust)
Search checked by:
TBC, TBC
Three-Part Question:
In haemodynamically unstable adults receiving prehospital critical care, how accurately does oscillometric non-invasive blood-pressure monitoring agree with femoral intra-arterial blood-pressure measurement?
Clinical Scenario:
A 25-year-old man has been struck by a car. He has sustained a severe head injury and significant blunt chest trauma. He is unconscious, tachycardic and peripherally cold, with repeated oscillometric blood-pressure measurements that are low, variable and occasionally unobtainable. The prehospital critical-care team needs reliable blood-pressure measurements to balance treatment of suspected haemorrhagic shock against the need to maintain adequate cerebral perfusion. They consider inserting a femoral arterial line and wonder how accurately oscillometric non-invasive blood-pressure monitoring reflects femoral intra-arterial pressure in this setting.
Search Strategy:
All searches were run on 13 August 2026. The initial femoral-specific searches were retained in the record, then supplemented with broader searches after benchmark-paper testing showed that arterial site was often absent from searchable titles, abstracts and indexing.
MEDLINE, EMBASE and Cochrane were searched using the OVID database.
Additional papers were sought through reviewing references of relevant papers.
MEDLINE, EMBASE and Cochrane were searched using the OVID database.
Additional papers were sought through reviewing references of relevant papers.
Search Details:
Ovid MEDLINE(R): 1946 to August Week 2 2026
Initial femoral-specific strategy
((exp Femoral Artery/ or (femoral adj3 (arter* or catheter* or cannul* or line*)).tw,kf.) and (((intraarterial or intra-arterial or invasive) adj3 (blood pressure or arterial pressure or pressure monitor*)).tw,kf. or ((arterial or artery) adj3 (catheter* or cannul* or line*) adj5 (pressure or monitor*)).tw,kf.)) and (Blood Pressure Determination/ or Blood Pressure Monitors/ or (oscillometr* or noninvasive blood pressure or non-invasive blood pressure or noninvasive BP or non-invasive BP or NIBP).tw,kf. or ((blood pressure or BP) adj3 (cuff* or noninvasive or non-invasive or oscillometr*)).tw,kf.)
Limit: humans. Result: 49 records.
Supplementary broad strategy
(((intraarterial or intra-arterial or invasive or direct) adj3 (blood pressure or arterial pressure or pressure monitor*)).tw,kf. or ((arterial or artery) adj3 (catheter* or cannul* or line* or manometr*) adj5 (pressure or monitor*)).tw,kf.) and ((oscillometr* or noninvasive blood pressure or non-invasive blood pressure or noninvasive BP or non-invasive BP or NIBP).ti,ab,kw. or ((blood pressure or BP) adj3 (cuff* or noninvasive or non-invasive or oscillometr*)).ti,ab,kw.)
Limit: humans.
Ovid Embase: 1974 to 2026 Week 32
Initial femoral-specific strategy
((exp femoral artery/ or (femoral adj3 (arter* or catheter* or cannul* or line*)).ti,ab,kw.) and (((intraarterial or intra-arterial or invasive) adj3 (blood pressure or arterial pressure or pressure monitor*)).ti,ab,kw. or ((arterial or artery) adj3 (catheter* or cannul* or line*) adj5 (pressure or monitor*)).ti,ab,kw.)) and (exp blood pressure measurement/ or exp blood pressure monitor/ or (oscillometr* or noninvasive blood pressure or non-invasive blood pressure or noninvasive BP or non-invasive BP or NIBP).ti,ab,kw. or ((blood pressure or BP) adj3 (cuff* or noninvasive or non-invasive or oscillometr*)).ti,ab,kw.)
Supplementary broad strategy
(((intraarterial or intra-arterial or invasive or direct) adj3 (blood pressure or arterial pressure or pressure monitor*)).tw,kf. or ((arterial or artery) adj3 (catheter* or cannul* or line* or manometr*) adj5 (pressure or monitor*)).tw,kf.) and ((oscillometr* or noninvasive blood pressure or non-invasive blood pressure or noninvasive BP or non-invasive BP or NIBP).ti,ab,kw. or ((blood pressure or BP) adj3 (cuff* or noninvasive or non-invasive or oscillometr*)).ti,ab,kw.)
COCHRANE database:
(femoral artery OR femoral arterial OR femoral catheter OR femoral cannula OR femoral cannulation) AND (oscillometric OR non-invasive blood pressure OR noninvasive blood pressure OR NIBP OR blood pressure cuff)
Initial femoral-specific strategy
((exp Femoral Artery/ or (femoral adj3 (arter* or catheter* or cannul* or line*)).tw,kf.) and (((intraarterial or intra-arterial or invasive) adj3 (blood pressure or arterial pressure or pressure monitor*)).tw,kf. or ((arterial or artery) adj3 (catheter* or cannul* or line*) adj5 (pressure or monitor*)).tw,kf.)) and (Blood Pressure Determination/ or Blood Pressure Monitors/ or (oscillometr* or noninvasive blood pressure or non-invasive blood pressure or noninvasive BP or non-invasive BP or NIBP).tw,kf. or ((blood pressure or BP) adj3 (cuff* or noninvasive or non-invasive or oscillometr*)).tw,kf.)
Limit: humans. Result: 49 records.
Supplementary broad strategy
(((intraarterial or intra-arterial or invasive or direct) adj3 (blood pressure or arterial pressure or pressure monitor*)).tw,kf. or ((arterial or artery) adj3 (catheter* or cannul* or line* or manometr*) adj5 (pressure or monitor*)).tw,kf.) and ((oscillometr* or noninvasive blood pressure or non-invasive blood pressure or noninvasive BP or non-invasive BP or NIBP).ti,ab,kw. or ((blood pressure or BP) adj3 (cuff* or noninvasive or non-invasive or oscillometr*)).ti,ab,kw.)
Limit: humans.
Ovid Embase: 1974 to 2026 Week 32
Initial femoral-specific strategy
((exp femoral artery/ or (femoral adj3 (arter* or catheter* or cannul* or line*)).ti,ab,kw.) and (((intraarterial or intra-arterial or invasive) adj3 (blood pressure or arterial pressure or pressure monitor*)).ti,ab,kw. or ((arterial or artery) adj3 (catheter* or cannul* or line*) adj5 (pressure or monitor*)).ti,ab,kw.)) and (exp blood pressure measurement/ or exp blood pressure monitor/ or (oscillometr* or noninvasive blood pressure or non-invasive blood pressure or noninvasive BP or non-invasive BP or NIBP).ti,ab,kw. or ((blood pressure or BP) adj3 (cuff* or noninvasive or non-invasive or oscillometr*)).ti,ab,kw.)
Supplementary broad strategy
(((intraarterial or intra-arterial or invasive or direct) adj3 (blood pressure or arterial pressure or pressure monitor*)).tw,kf. or ((arterial or artery) adj3 (catheter* or cannul* or line* or manometr*) adj5 (pressure or monitor*)).tw,kf.) and ((oscillometr* or noninvasive blood pressure or non-invasive blood pressure or noninvasive BP or non-invasive BP or NIBP).ti,ab,kw. or ((blood pressure or BP) adj3 (cuff* or noninvasive or non-invasive or oscillometr*)).ti,ab,kw.)
COCHRANE database:
(femoral artery OR femoral arterial OR femoral catheter OR femoral cannula OR femoral cannulation) AND (oscillometric OR non-invasive blood pressure OR noninvasive blood pressure OR NIBP OR blood pressure cuff)
Outcome:
MEDLINE:
Initial femoral-specific strategy — 49 records
Supplementary broad strategy — 1,268 records
EMBASE
Initial femoral-specific strategy — 142 records
Supplementary broad strategy — 3,588 records
Cochrane Library: CENTRAL
Pragmatic keyword strategy — 236 records
Initial femoral-specific strategy — 49 records
Supplementary broad strategy — 1,268 records
EMBASE
Initial femoral-specific strategy — 142 records
Supplementary broad strategy — 3,588 records
Cochrane Library: CENTRAL
Pragmatic keyword strategy — 236 records
Relevant Paper(s):
| Study Title | Patient Group | Study type (level of evidence) | Outcomes | Key results | Study Weaknesses |
|---|---|---|---|---|---|
| Non-invasive versus arterial pressure monitoring in the pre-hospital critical care environment: a paired comparison of concurrently recorded measurements. Perera Y, Raitt J, Poole K, et al. 2024 UK | 221 adults attended by a UK prehospital critical-care service; 2,359 paired readings. 34 patients had femoral lines. Cardiac arrest and major trauma predominated. | Retrospective single-service paired comparison of concurrent oscillometric NIBP and arterial manometry. | Pairwise agreement; regression-based Bland–Altman analysis; effects of shock, severe hypertension, transport and catheter site. | Overall agreement was clinically poor. In shock: acceptable agreement SBP 50.6%, DBP 67.1%, MAP 39.8%. Shock reduced agreement: SBP aOR 0.52; DBP 0.65; MAP 0.53. Femoral line reduced MAP agreement: aOR 0.65. NIBP overestimated SBP/MAP at low pressures and underestimated them at high pressures. | Retrospective; single service and monitor system; repeated observations clustered within patients; only five shocked individuals generated 261 observations; femoral subgroup small; implausible readings excluded; pragmatic agreement thresholds generous. |
| Accuracy of blood pressure measurements made aboard helicopters. Low RB, Martin D. 1988 USA | 20 critically ill helicopter patients; 222 comparisons; arterial sites predominantly radial. | Prospective simultaneous direct, palpation, Doppler and oscillometric comparisons during helicopter transport. | Measurement error and failure to obtain readings. | Oscillometric SBP error 0 ± 33 mmHg; MAP error +10 ± 15 mmHg; DBP error +10 ± 10 mmHg. Some substantial invasive pressures were undetectable non-invasively. | Small heterogeneous cohort; older devices; multiple techniques and unequal observations; mainly radial rather than femoral reference; transport technology differs from current practice. |
| Blood pressure measurement during transport: a comparison of direct and oscillotonometric readings in critically ill patients. Runcie CJ, Reeve WG, Reidy J, Dougall JR. 1990 USA | 44 critically ill transported patients divided across four portable monitor groups; mixed arterial sites, radial preferred where feasible. | Prospective comparison of simultaneous direct and oscillotonometric measurements during transport. | Device-specific proportional bias, 95% limits of agreement and invalid/unobtainable readings. | Devices under-read SBP by 13%, 21%, 19% and 13%; over-read DBP by 15%, 5%, 27% and 15%. Limits of agreement were broad; e.g. Dinamap SBP ranged from 34% below to 15% above direct pressure. | Small groups for each device; mixed arterial sites; older devices; invalid motion-affected readings removed; proportional/log-transformed outcomes complicate interpretation |
| Comparison of non-invasive and invasive blood pressure in aeromedical care. McMahon N, Hogg LA, Corfield AR, Exton AD. 2012 UK | 56 critically ill aeromedical retrieval patients with complete paired pre-flight and in-flight data. | Retrospective paired comparison using Propaq Encore; one paired set before flight and one during flight. | Bias and Bland–Altman 95% limits of agreement for SBP and MAP. | Pre-flight SBP −37.3 to 30.0 mmHg; MAP −20.5 to 25.0. In-flight SBP −40.6 to 33.1; MAP −23.6 to 24.6. Bias across analyses +0.6 to −3.8 mmHg. Flight did not worsen agreement. | Only 56 of 251 eligible patients had complete data; small study; arterial site not reported; retrospective; correct cuff size assumed; simultaneous NIBP sometimes switched off. |
Author Commentary:
The evidence shows that NIBP is unreliable. Several studies report modest mean bias but very wide limits of agreement, meaning individual NIBP readings may differ enough from invasive pressure to alter treatment. This is most concerning at physiological extremes.
Perera et al. provides the most applicable evidence. NIBP systematically overestimated SBP and MAP during hypotension and underestimated them during severe hypertension. Such direction-dependent error can conceal shock, delay vasopressor or fluid treatment, or mask dangerous hypertension. The same pattern is supported by older transport and hospital studies.
The evidence does not establish that inserting a prehospital femoral arterial catheter improves patient-centred outcomes. Decisions must balance the value of continuous, more central pressure measurement against insertion time, training requirements and complications. Applicability is strongest when cuff readings are inconsistent or unobtainable, vasoactive treatment is being titrated, or tight pressure control is clinically important.
Only Perera et al. reported a femoral subgroup, and this comprised 34 patients. Low and Runcie predominantly used radial arterial measurements, while McMahon did not report arterial site. The evidence therefore supports concern about the interchangeability of NIBP and invasive pressure during prehospital care, but the femoral-specific evidence remains limited.
Perera et al. provides the most applicable evidence. NIBP systematically overestimated SBP and MAP during hypotension and underestimated them during severe hypertension. Such direction-dependent error can conceal shock, delay vasopressor or fluid treatment, or mask dangerous hypertension. The same pattern is supported by older transport and hospital studies.
The evidence does not establish that inserting a prehospital femoral arterial catheter improves patient-centred outcomes. Decisions must balance the value of continuous, more central pressure measurement against insertion time, training requirements and complications. Applicability is strongest when cuff readings are inconsistent or unobtainable, vasoactive treatment is being titrated, or tight pressure control is clinically important.
Only Perera et al. reported a femoral subgroup, and this comprised 34 patients. Low and Runcie predominantly used radial arterial measurements, while McMahon did not report arterial site. The evidence therefore supports concern about the interchangeability of NIBP and invasive pressure during prehospital care, but the femoral-specific evidence remains limited.
Bottom Line:
Oscillometric NIBP and invasive arterial pressure should not be considered interchangeable in haemodynamically unstable prehospital patients. Agreement is particularly poor at blood-pressure extremes: NIBP may overestimate SBP and MAP during hypotension and underestimate them during severe hypertension. Invasive monitoring may therefore provide clinically important information when accurate, continuous pressure measurement is required. However, femoral-specific prehospital evidence is limited and there is no evidence that prehospital femoral monitoring improves patient outcomes.
Level of Evidence:
Level 3: Small numbers of small studies or great heterogeneity or very different population
References:
- Perera Y, Raitt J, Poole K, et al.. Non-invasive versus arterial pressure monitoring in the pre-hospital critical care environment: a paired comparison of concurrently recorded measurements.
- Low RB, Martin D.. Accuracy of blood pressure measurements made aboard helicopters.
- Runcie CJ, Reeve WG, Reidy J, Dougall JR.. Blood pressure measurement during transport: a comparison of direct and oscillotonometric readings in critically ill patients.
- McMahon N, Hogg LA, Corfield AR, Exton AD.. Comparison of non-invasive and invasive blood pressure in aeromedical care.