Does the pre-hospital insertion of an arterial line increase time on scene?
Date First Published:
January 21, 2026
Last Updated:
January 21, 2026
Report by:
Dr Jack Lyon & Sam Garner, Emergency Medicine ACCS ST2 & 5th Year Medical Student (Manchester Royal Infirmary & University of Manchester)
Search checked by:
Dr Gregory Yates, Emergency Medicine ST3
Three-Part Question:
In [patients attended by an enhanced pre-hospital care service] is [the pre-hospital insertion of an arterial line] associated with [an increase in time on scene].
Clinical Scenario:
You are a doctor working with an enhanced pre-hospital care team, tasked to a severely injured patient. They are comatose with a head injury and require a pre-hospital emergency anaesthetic. You consider inserting an arterial line for invasive blood pressure monitoring to optimise your pre-hospital emergency anaesthesia (PHEA) and/or improve your haemodynamic monitoring. You are cognisant however of minimising time on scene and wonder whether this may delay their transport to definitive care.
Search Strategy:
A database search was conducted using both MEDLINE (1946-2025) and EMBASE (1975-2025) via the Ovid interface to identify relevant studies. The search was conducted using the following keywords:
Air ambulance (exp) or pre-hospital or pre-hospital emergency medicine or Emergency medical service (exp) or Helicopter Emergency Medical Service$ or HEMS or enhanced pre-hospital care or prehospital or prehospital emergency medicine
AND
Arterial line$ or invasive arterial blood pressure or arterial catheter or arterial cannula or arterial catheterisation or arterial cannulation or intra-arterial blood pressure
The results were de-duplicated and exported to a Microsoft Excel spreadsheet. Following this, each paper was reviewed and screened against eligibility criteria. Each eligible paper was then searched using the Google Scholar ‘cited by’ function. This identified any additional studies that had referenced our eligible papers. Lastly, the reference list of each paper was screened to identify any studies missed by our search.
Air ambulance (exp) or pre-hospital or pre-hospital emergency medicine or Emergency medical service (exp) or Helicopter Emergency Medical Service$ or HEMS or enhanced pre-hospital care or prehospital or prehospital emergency medicine
AND
Arterial line$ or invasive arterial blood pressure or arterial catheter or arterial cannula or arterial catheterisation or arterial cannulation or intra-arterial blood pressure
The results were de-duplicated and exported to a Microsoft Excel spreadsheet. Following this, each paper was reviewed and screened against eligibility criteria. Each eligible paper was then searched using the Google Scholar ‘cited by’ function. This identified any additional studies that had referenced our eligible papers. Lastly, the reference list of each paper was screened to identify any studies missed by our search.
Search Details:
Inclusion
- Patients attended by an enhanced pre-hospital care service.
- Arterial line inserted in the pre-hospital setting.
- On scene times reported.
Exclusion
- Non-empirical studies (e.g. editorials)
- Case reports and case series
- Patients attended by an enhanced pre-hospital care service.
- Arterial line inserted in the pre-hospital setting.
- On scene times reported.
Exclusion
- Non-empirical studies (e.g. editorials)
- Case reports and case series
Outcome:
Our search identified a total of 468 papers. 456 were removed following title and abstract re-view as they were not relevant to our question. Of the remaining 12 papers, eight were exclud-ed following full text review because they didn’t contain original data on scene times. One of these papers was identified from screening the references of other eligible papers.
A total of four relevant papers were identified that met our eligibility criteria.
A total of four relevant papers were identified that met our eligibility criteria.
Relevant Paper(s):
| Study Title | Patient Group | Study type (level of evidence) | Outcomes | Key results | Study Weaknesses |
|---|---|---|---|---|---|
| Implementing prehospital invasive arterial blood pressure monitoring in critically ill patients-a prospective observational first year analysis. Jakob Ule, Tobias Hüppe, Julian Thiel, Ulrich Berwanger, Thomas Schlechtriemen, David Conrad and Benedikt Merscher 2025 Germany | Number of patients with indication for arterial line insertion = 108 Number of patients who had a pre-hospital arterial line insertion attempt = 68. Male 60.2%. Average age 66. Patients requiring CPR - 57% Polytrauma patients = 9% | Single-centre. Prospective observational cohort study. | Mean time on scene (pre-hospital arterial line insertion vs no insertion) | + 7.4 minutes | Prospective observational cohort study, creating a risk of selection bias and confounding. Conducted in a single organisation with a physician-staffed EMS system limits generalisability. Small number of cases with 68 IABP attempts and 60 successful insertions. Clinician-driven case selection, so groups may differ in illness severity. IABP criteria stated but implementation was not standardised, introducing variation in practice. No predefined control group or confirmed baseline comparability, limiting internal validity. Scene time derived from routine timestamps rather than direct observation, introducing potential measurement inaccuracy. |
| Association of prehospital invasive blood pressure measurement and treatment times of intubated patients with suspected stroke – a retrospective study. Michael Eichlseder, Nikolaus Schreiber, Alexander Pichler, Michael Eichinger, Sebastian Labenbacher, Barbara Hallmann, Simon Orlob, Paul Zajic and Simon Fandler‑Höfler 2025 Austria | Number of patients who were attended as a primary mission with a suspected stroke, received a pre-hospital emergency anaesthetic and had an arterial line inserted = 100 Number of patients who had a pre-hospital arterial line = 67 Male 57%. Average age = 72yrs Initial median GCS = 5. | Single-centre. Retrospective observational cohort study. | Median time on scene (pre-hospital arterial line insertion vs in-hospital). | + 9 minutes | Retrospective single-centre design with risk of selection bias. Propensity-score matching attempts to reduced differences between groups. Risk of residual confounding. Conducted in a single physician-staffed Austrian EMS/HEMS system, reducing generalisability. Small matched sample (33 per group) lowers statistical robustness, and exclusions for missing or incomplete records introduce selection bias. IABP use was clinician-driven with no protocol. Failed or abandoned attempts could not be identified. Scene time and treatment intervals were derived from registry timestamps without validation, introducing potential measurement inaccuracy. |
| Median time from on scene arrival to CT head (pre-hospital arterial line insertion vs in-hospital). | + 6 minutes | ||||
| Is time to first CT scan in patients with isolated severe traumatic brain injury prolonged when Prehospital Arterial Cannulation is performed? A retrospective non-inferiority study. Michael Eichlseder, Sebastian Labenbacher, Alexander Pichler, Michael Eichinger, Thomas Kuenzer, Philipp Zoidl, Barbara Hallmann, Felix Stelzl, Nikolaus Schreiber and Paul Zajic 2024 Austria | Number of patients with isolated severe traumatic brain injury (AIS > 3 in head region, GCS 2 in any other body region) who received a pre-hospital emergency anaesthetic, had an arterial line inserted and went for a CT head directly following initial resuscitation room treatment = 181. Number of patients who had a pre-hospital arterial line = 87. Male 66.9%. Median age 66 Initial median GCS = 4 Median ISS = 25 (Identical in both groups). | Single-centre. Retrospective observational non-inferiority study. | Median time on scene (pre-hospital arterial line insertion vs in-hospital) | + 4 minutes | Retrospective non-inferiority cohort design with risk of selection bias. Single Austrian tertiary centre with physician-staffed HEMS limits generalisability. Planned sample size not reached, reducing power. Arterial cannulation identified retrospectively, with failed or undocumented attempts excluded, potentially underestimating delays. No randomisation or confirmed baseline comparability between groups, leaving residual confounding. Scene time and CT timings drawn from registry timestamps without validation, introducing possible measurement inaccuracy. |
| Median time from on scene arrival to CT head (pre-hospital arterial line insertion vs in-hospital) | - 2 minutes | ||||
| Predictors of prehospital on scene time in an Australian emergency retrieval service. Patrick T. Fok , David Teubner , Jeremy Purdell-Lewis and Andrew Pearce 2019 Australia | Total number of primary missions = 506. Male 68%. Mean age 41. Number of patients who had a pre-hospital arterial line = 19. | Single-centre. Retrospective observational cohort study. | Mean time on scene (pre-hospital arterial line insertion vs no insertion). | + 34.4 minutes | Retrospective non-randomised design with risk of selection bias and confounding. Single organisation with a physician-led retrieval system limits generalisability. Remote geographical setting of retrieval service changes clinical interventions and priorities due to prolonged transport times. Reduced generalisability to urban settings. Very small arterial-line subgroup (n = 19, 3.8%) and heterogeneous case mix. Infrequent insertion will likely reduce familiarity with procedure and increase insertion times. Scene time obtained from registry smartphone timestamps without reported validation, introducing potential timing inaccuracy. |
Author Commentary:
Arterial lines are the standard of care in-hospital for blood pressure monitoring in critically unwell patients. Continuous blood pressure monitoring allows clinicians to accurately understand their patient’s physiology and tailor their interventions accordingly to improve outcomes. Globally, multiple enhanced pre-hospital care (EPHC) services have demonstrated the feasibility of delivering this monitoring pre-hospital. The question is, does establishing this cause a significant delay on scene and, if so, is this clinically meaningful?
All four studies identified in our search noted an association between arterial line insertion and increased scene time (4 to 34.4 minutes). The strength and interpretability of this evidence, however, is limited.
From a methodological perspective, none of the identified papers directly measured the procedural time required to insert an arterial line or isolated its specific contribution to overall scene time. Instead, most studies retrospectively compared patients deemed eligible for an arterial line, contrasting those who received an arterial line with those who did not. Whilst attempts were made to account for confounding variables, such as matching patient characteristics or adjusting for known contributing factors that prolong scene time, this is inherently difficult to fully mitigate in this study design. Additionally, the studies included have not been able to report the nuances in patient acuity, physiological instability or the specific details of concurrent interventions such as pre-hospital emergency anaesthesia (PHEA). These pieces of information will heavily influence the clinician’s decision making process surrounding arterial line insertion and time on scene, yet these studies fail to capture this rationale.
Exploring whether increased scene time is clinically important is challenging. For some patients, rapid transfer to a place of definitive management is required. This is most apparent in a haemorrhaging poly-trauma patient for example. However, a longer scene time in which enhanced monitoring and interventions can be established may be of greater benefit for others. For example, preventing secondary insult in patients with a traumatic brain injury (TBI).
In TBI, we know that periods of hypo- or hypertension are deleterious. Therefore, it is imperative to have accurate BP monitoring to maintain good BP control. Furthermore, research tells us that pre-hospital non-invasive blood pressure (NIBP) readings are often incongruous with IABP readings, and that this discordance is amplified at the extremes of hypo- or hypertension (5, 6). The potential to earlier implement accurate BP monitoring, identify periods of hypo- or hypertension and intervene has the potential to make a material difference in outcomes.
Whilst not examining scene time directly, two additional studies have investigated the time required to insert and set up an arterial line in the pre-hospital setting. One reported a median of 2 minutes for cannulation and 3 minutes for equipment setup, while another identified a median time of 12 minutes from opening the arterial line pack to obtaining the first IABP measurement (7,8). One UK based HEMS service reported that 39% of their arterial lines were inserted whilst enroute to hospital (9). Whilst unclear if this was carried out in moving transport or whether transportation was paused to allow safer insertion, this may present a method of reducing on scene time if cannulation can be done when stationery with the remaining elements performed whilst mobile. Additionally, there is variation in team numbers, composition and scope of practice between services. Optimising this may also convey a benefit.
(5) Griggs, J. et al. (2025) Diagnostic accuracy of pre-hospital invasive arterial blood pressure monitoring for haemodynamic management in traumatic brain injury and spontaneous intracranial haemorrhage. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine, doi:10.1186/s13049-025-01393-4
(6) Perrera, Y. et al. (2024) Non-invasive versus arterial pressure monitoring in the pre-hospital critical care environment: a paired comparison of concurrently recorded measurements. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine, doi: 10.1186/s13049-024-01240-y
(7) Wildner, G. et al. (2011) Arterial line in prehospital emergency settings – a feasibility study in four physician-staffed emergency medical systems. Resuscitation, 82(9), pp. 1198–1201. doi:10.1016/j.resuscitation.2011.05.002.
(8) Sende, J. et al. (2009) Invasive arterial blood pressure monitoring in an out-of-hospital setting: An observational study. Emergency Medicine Journal, 26(3), pp. 210–212. doi:10.1136/emj.2008.060608.
(9) Butterfield, E. et al. (2024) Prehospital invasive arterial blood pressure monitoring in critically ill patients attended by a UK Helicopter Emergency Medical Service – a retrospective observational review of practice. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine, doi:10.1186/s13049-024-01193-2.
All four studies identified in our search noted an association between arterial line insertion and increased scene time (4 to 34.4 minutes). The strength and interpretability of this evidence, however, is limited.
From a methodological perspective, none of the identified papers directly measured the procedural time required to insert an arterial line or isolated its specific contribution to overall scene time. Instead, most studies retrospectively compared patients deemed eligible for an arterial line, contrasting those who received an arterial line with those who did not. Whilst attempts were made to account for confounding variables, such as matching patient characteristics or adjusting for known contributing factors that prolong scene time, this is inherently difficult to fully mitigate in this study design. Additionally, the studies included have not been able to report the nuances in patient acuity, physiological instability or the specific details of concurrent interventions such as pre-hospital emergency anaesthesia (PHEA). These pieces of information will heavily influence the clinician’s decision making process surrounding arterial line insertion and time on scene, yet these studies fail to capture this rationale.
Exploring whether increased scene time is clinically important is challenging. For some patients, rapid transfer to a place of definitive management is required. This is most apparent in a haemorrhaging poly-trauma patient for example. However, a longer scene time in which enhanced monitoring and interventions can be established may be of greater benefit for others. For example, preventing secondary insult in patients with a traumatic brain injury (TBI).
In TBI, we know that periods of hypo- or hypertension are deleterious. Therefore, it is imperative to have accurate BP monitoring to maintain good BP control. Furthermore, research tells us that pre-hospital non-invasive blood pressure (NIBP) readings are often incongruous with IABP readings, and that this discordance is amplified at the extremes of hypo- or hypertension (5, 6). The potential to earlier implement accurate BP monitoring, identify periods of hypo- or hypertension and intervene has the potential to make a material difference in outcomes.
Whilst not examining scene time directly, two additional studies have investigated the time required to insert and set up an arterial line in the pre-hospital setting. One reported a median of 2 minutes for cannulation and 3 minutes for equipment setup, while another identified a median time of 12 minutes from opening the arterial line pack to obtaining the first IABP measurement (7,8). One UK based HEMS service reported that 39% of their arterial lines were inserted whilst enroute to hospital (9). Whilst unclear if this was carried out in moving transport or whether transportation was paused to allow safer insertion, this may present a method of reducing on scene time if cannulation can be done when stationery with the remaining elements performed whilst mobile. Additionally, there is variation in team numbers, composition and scope of practice between services. Optimising this may also convey a benefit.
(5) Griggs, J. et al. (2025) Diagnostic accuracy of pre-hospital invasive arterial blood pressure monitoring for haemodynamic management in traumatic brain injury and spontaneous intracranial haemorrhage. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine, doi:10.1186/s13049-025-01393-4
(6) Perrera, Y. et al. (2024) Non-invasive versus arterial pressure monitoring in the pre-hospital critical care environment: a paired comparison of concurrently recorded measurements. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine, doi: 10.1186/s13049-024-01240-y
(7) Wildner, G. et al. (2011) Arterial line in prehospital emergency settings – a feasibility study in four physician-staffed emergency medical systems. Resuscitation, 82(9), pp. 1198–1201. doi:10.1016/j.resuscitation.2011.05.002.
(8) Sende, J. et al. (2009) Invasive arterial blood pressure monitoring in an out-of-hospital setting: An observational study. Emergency Medicine Journal, 26(3), pp. 210–212. doi:10.1136/emj.2008.060608.
(9) Butterfield, E. et al. (2024) Prehospital invasive arterial blood pressure monitoring in critically ill patients attended by a UK Helicopter Emergency Medical Service – a retrospective observational review of practice. Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine, doi:10.1186/s13049-024-01193-2.
Bottom Line:
The pre-hospital insertion of an arterial line is associated with an increase in time on scene. However, the evidence for this is not robust and is subject to significant confounding. The clinical significance of this delay is unclear and is likely to be context specific. Further research is required to identify which patient groups derive most benefit from IABP monitoring and how this can be optimally integrated into pre-hospital care without adversely impacting time to definitive treatment.
Level of Evidence:
Level 3: Small numbers of small studies or great heterogeneity or very different population
References:
- Jakob Ule, Tobias Hüppe, Julian Thiel, Ulrich Berwanger, Thomas Schlechtriemen, David Conrad and Benedikt Merscher. Implementing prehospital invasive arterial blood pressure monitoring in critically ill patients-a prospective observational first year analysis.
- Michael Eichlseder, Nikolaus Schreiber, Alexander Pichler, Michael Eichinger, Sebastian Labenbacher, Barbara Hallmann, Simon Orlob, Paul Zajic and Simon Fandler‑Höfler. Association of prehospital invasive blood pressure measurement and treatment times of intubated patients with suspected stroke – a retrospective study.
- Michael Eichlseder, Sebastian Labenbacher, Alexander Pichler, Michael Eichinger, Thomas Kuenzer, Philipp Zoidl, Barbara Hallmann, Felix Stelzl, Nikolaus Schreiber and Paul Zajic. Is time to first CT scan in patients with isolated severe traumatic brain injury prolonged when Prehospital Arterial Cannulation is performed? A retrospective non-inferiority study.
- Patrick T. Fok , David Teubner , Jeremy Purdell-Lewis and Andrew Pearce. Predictors of prehospital on scene time in an Australian emergency retrieval service.