Intensive and critical care

Energy, flow and pressure in the cardiovascular system: a narrative review of how the circulation works (2026)

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Type of publication:

Journal article

Author(s):

*Miller, Ashley; Kirk-Bayley, Justin; Peck, Marcus; Wilkinson, Jonathan.

Citation:

Anaesthesia. 81(10):1386-1399, 2026 Oct.

Abstract:

INTRODUCTION: Understanding what determines blood flow in the circulation is central to haemodynamic management in anaesthesia and critical care. Traditional teaching emphasises pressure-based concepts, such as preload; afterload; central venous pressure; and venous return curves. However, these frameworks generate confusion about causality and control. Interpreting pressure variables as drivers of flow has contributed to inconsistent physiological reasoning and potentially harmful treatment. This narrative review re-examines how blood flow is generated and regulated, integrating classical physiology with contemporary mechanisms and provides a coherent clinical framework.

METHODS: We performed a search of MEDLINE and Embase with key terms, supplemented by citation tracking. We also included seminal physiological studies.

RESULTS: The reviewed literature showed that blood flow is constrained by energy supply from the heart and pressure established by vascular volume, elastance and the impedance of the inflow pathway to the heart. Mean systemic pressure reflects potential energy stored within the compliant venous system but does not drive flow. Right atrial pressure and preload are dependent variables that report the equilibrium between venous return and cardiac function, but do not control flow. Starling's mechanism provides passive mechanical matching of inflow to outflow but does not regulate cardiac output actively. Resistance-based interpretations alone fail to account for the influence of compliance, impedance and pulsatility. Misinterpretation of graphical and algebraic representations, particularly venous return curves, has obscured these relationships.

DISCUSSION: We describe a unified physiological framework in which the heart supplies energy, vascular properties define what flow is possible, and pressures reflect system state rather than driving forces. This model reconciles historically opposing paradigms and clarifies the limits of pressure-targeted resuscitation. Clinically, it promotes assessing flow responsiveness and cardiac reserve over static pressure targets, and provides a mechanistic basis for contemporary shock management, thus avoiding interventions that increase congestion without improving perfusion.

DOI: 10.1111/anae.70238

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Developing a comprehensive haemodynamic ultrasound assessment for critical care: Rationale and methodology from the FUSIC programme (2026)

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Type of publication:

Journal article

Author(s):

*Miller, Ashley; Peck, Marcus; Conway, Hannah; Parulekar, Prashant; Rubino, Antonio; Stephens, Jennie; Wilkinson, Jonathan; Kirk-Bayley, Justin; Waraich, Manni; Griksaitis, Michael.

Citation:

The Journal of the Intensive Care Society. 17511437261470613, 2026 Jul 31.

Abstract:

Haemodynamic ultrasound is central to bedside assessment of circulatory failure in critical care. The Focused UltraSound in Intensive Care HaemoDynamics (FUSIC HD) programme was originally designed to provide a structured national framework for physiologically focused ultrasound assessment, distinct from comprehensive diagnostic echocardiography. Since publication of the original framework, experience from training cohorts, logbook review, and centralised summative assessment has shown that a broader range of haemodynamic parameters can be acquired and interpreted in routine practice. This article outlines the rationale, development process, and methodological principles underpinning the recent revision of the FUSIC HD dataset. The updated framework incorporates additional assessment of left ventricular performance, right ventricular function, and pulmonary vascular loading, together with a refined approach to estimating left atrial pressure while maintaining emphasis on physiological coherence, bedside feasibility, and avoidance of unnecessary diagnostic complexity. The aim is not to expand diagnostic echocardiography capability, but to support more integrated haemodynamic interpretation in critically ill patients within an established training and governance structure.

DOI: 10.1177/17511437261470613

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The 2026 Surviving Sepsis Campaign Guidelines: The dissenting opinion (2026)

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Type of publication:

Journal article

Author(s):

Spiegel, Rory; Haycock, Korbin; *Miller, Ashley; Weingart, Scott; Farkas, Joshua; Ajmo, Ian; Rola, Philippe.

Citation:

American Journal of Emergency Medicine. 110:411-415, 2026 Sep 15.

Abstract:

The Surviving Sepsis Campaign (SSC) Guidelines once represented what was considered the pinnacle of care for patients with sepsis and septic shock. Unfortunately, over the past decade, successive iterations of the guidelines have drifted from what is now considered optimal care for critically ill patients with sepsis and septic shock. Moreover, the guidelines have shifted from recommendations intended to guide and support physicians based on the best available evidence, to mandated "bundles" which exert substantial influence over what is considered "standard of care" in sepsis management. This. Document is intended to serve as a refutation of sorts. A rebuttal to the most controversial and influential recommendations in the Surviving Sepsis Campaign Guidelines, while also offering guidance on how clinicians might move beyond the protocolized, metric-based care that has become the current standard promoted by the SSC and similar organizations.

DOI: 10.1016/j.ajem.2026.09.025

The spiked helmet sign in severe sepsis: an unusual electrocardiographic finding in a critically ill patient (2025)

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Type of publication:

Journal article

Author(s):

Manea, Hashim; Alhatemi, Ahmed Qasim Mohammed; Al-Ghuraibawi, Mohammedbaqer Ali; *Alhumairi, Ghaith Asaad; Al-Shammari, Ali Saad; Al-Ibraheem, Abdullah Muataz Taha; Ahmad, Ibrar; Abdulammer, Hussein Safaa.

Citation:

Oxford Medical Case Reports. 2025(11):omaf232, 2025 Nov.

Abstract:

Background: The 'spiked helmet' sign is a rare electrocardiographic (ECG) phenomenon characterized by transient ST-segment elevations mimicking an acute coronary syndrome, typically seen in critically ill patients. While often associated with severe physiological stress, its presence in sepsis is particularly uncommon.

Case Presentation: A 68-year-old male with a history of hypertension and diabetes mellitus presented to the emergency department with fever, altered mental status, and hypotension. Initial workup revealed severe sepsis secondary to pneumonia. His ECG showed pronounced ST-segment elevations in leads II, III, and aVF, with a distinctive 'spiked helmet' pattern. Troponin levels were mildly elevated, raising concerns for concurrent myocardial ischemia. However, the patient denied chest pain, and further cardiac evaluation, including echocardiography, showed no evidence of ischemia or infarction. Intensive care management included broad-spectrum antibiotics, intravenous fluids, and vasopressors. Despite the severity of his illness, the patient's condition gradually improved, and repeat ECGs showed resolution of the ST-segment elevations. The 'spiked helmet' sign was attributed to severe sepsis-induced autonomic dysfunction rather than primary cardiac pathology.

Conclusion: This case highlights the importance of recognizing the 'spiked helmet' sign as a marker of severe stress in critically ill patients, which may mimic myocardial ischemia on ECG. Prompt differentiation between this sign and true ischemia is crucial to avoid unnecessary interventions and focus on managing the underlying critical illness.

DOI: 10.1093/omcr/omaf232

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Diagnosis of Shock States (2025)

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Type of publication:

Journal article

Author(s):

*Miller A.; Wilkinson J.; Kasal J.

Citation:

Critical Care Clinics. 41(3):397-428, 2025 Jul.

Abstract:

Shock is a common and deadly illness with a dynamic course over time. Echocardiography is an essential diagnostic tool in the management of shock. Each phase of shock management requires a specific approach with different echocardiographic goals. The initial goal of echocardiography is to diagnose the cause of shock, followed by treatment optimization, stabilization, and deescalation. The initial examination is rapid and based on the recognition of patterns (low mean systemic pressure, left and right heart failure, tamponade, and catastrophic valve failure) using a qualitative 2-dimensional examination with selected Doppler techniques. Subsequent examinations are often more detailed, semiquantitative, and quantitative. 

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The use of echocardiography in the management of shock in critical care: a prospective, multi-centre, observational study (2024)

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Type of publication:
Journal article

Author(s):
Flower, Luke; Waite, Alicia; Boulton, Adam; Peck, Marcus; Akhtar, Waqas; Boyle, Andrew J; Gudibande, Sandeep; Ingram, Thomas E; Johnston, Brian; Marsh, Sarah; *Miller, Ashley; Nash, Amy; Olusanya, Olusegun; Parulekar, Prashant; Wagstaff, Daniel; Wilkinson, Jonathan; Proudfoot, Alastair G.

Citation:
Intensive Care Medicine. 2024 Oct;50(10):1668-1680.

Abstract:
PURPOSE: Echocardiography is recommended as a first-line tool in the assessment of patients with shock. The current provision of echocardiography in critical care is poorly defined. The aims of this work were to evaluate the utilisation of echocardiography in patients presenting to critical care with shock, its impact on decision making, and adherence to governance guidelines. METHODS: We conducted a prospective, multi-centre, observational study in 178 critical care units across the United Kingdom (UK) and Crown Dependencies, led by the UK's Trainee Research in Intensive Care Network. Consecutive adult patients (>= 18 years) admitted with shock were followed up for 72 h to ascertain whether they received an echocardiogram, the nature of any scan performed, and its effect on critical treatment decision making. RESULTS: 1015 patients with shock were included. An echocardiogram was performed on 545 (54%) patients within 72 h and 436 (43%) within 24 h of admission. Most scans were performed by the critical care team (n = 314, 58%). Echocardiography was reported to either reduce diagnostic uncertainty or change management in 291 (54%) cases. Patients with obstructive or cardiogenic shock had their management altered numerically more often by echocardiography (n = 15 [75%] and n = 100 [58%] respectively). Twenty-five percent of echocardiograms performed adhered to current national governance and image storage guidance. CONCLUSION: Use of echocardiography in the assessment of patients with shock remains heterogenous. When echocardiography is used, it improves diagnostic certainty or changes management in most patients. Future research should explore barriers to increasing use of echocardiography in assessing patients presenting with shock.

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A survey of United Kingdom intensive care echocardiography provision (2024)

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Type of publication:
Journal article

Author(s):
Akhtar W.; Marshal L.; Buglass H.; Billyard T.; Goedvolk C.; Mildner R.; Conway H.; Soliman Aboumarie H.; *Miller A.; Peck M.; Rubino A.

Citation:
Journal of the Intensive Care Society. 2024 Jul 27;25(4):407-409

Abstract:
This study, conducted under the oversight of National Health Service Blood & Transplant, aimed to evaluate the current feasibility and implementation of both comprehensive and focused donor echocardiography in United Kingdom Intensive Care Units through a nationwide survey. Responses from 95 hospitals across all 4 UK nations showed each ICU had median 4 (IQR 2, 6) personal with 3 (IQR 2, 5) consultants and 1 (IQR 0, 2) registrar trained in focused echocardiography. A comprehensive echocardiogram can be acquired in 48% (n = 46) of hospitals within 6 h during regular working hours. This percentage drops to 11% (n = 10) outside of regular working hours, with 53% (n = 50) indicating this would require more than 24 h. In the case of focused echocardiogram acquisition, 60% (n = 57) of hospitals can obtain it within 6 h during normal working hours. This figure decreases to 20% (n = 19) outside of regular working hours, with 32% (n = 30) indicating that this would require more than 24 h to obtain. Overall, 98% of responding units (n = 93) have point-of-care ultrasound machines (median 2 (IQR 2, 3) machines per ICU) all equipped with echocardiographic capabilities. However, only 52% (n = 49) of respondents indicated have the ability for remote viewing of echocardiogram images.

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Mitral valve prolapse presenting as a missed myocardial infarction (2023)

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Type of publication:Conference abstract

Author(s):*Champaneri K.; *Miller A.

Citation:Journal of the Intensive Care Society. Conference: Intensive Care Society State of the Art Congress, SOA 2023. Birmingham United Kingdom. 24(2 Supplement) (pp 194), 2023. Date of Publication: August 2023.

Abstract:Introduction: An elderly but very active gentleman presented overnight with progressive shortness of breath and leg swelling, two weeks after experiencing chest pain while lifting heavy objects in the garden. The presumed diagnosis was a missed myocardial infarction leading to heart failure exacerbated by a new diagnosis of atrial fibrillation. Despite diuresis and rate control, he became progressively more hypoxic and was taken to ICU for non-invasive ventilation. An initial POCUS scan of heart and lungs by an ultrasound fellow undertaking FUSIC accreditation showed a hyperdynamic heart, pulmonary oedema, and bilateral pleural effusions. The echocardiogram was reviewed and repeated by an advanced level operator which dramatically altered the patient's diagnosis and management. Main body: A gentleman in his early 80s presented to the Emergency Department in type one respiratory failure with a high work of breathing. Examination and investigations demonstrated raised inflammatory markers, new atrial fibrillation with a rate of 140, large bilateral plural effusions, and pitting oedema to the groin. Troponin was normal, and the BNP was 4500. ECG showed no ischaemic changes and CXR was consistent with fluid overload and/or pneumonia. Initial management consisted of supplemental oxygen, diuretics, heart rate control, and antibiotics. Despite this his oxygenation deteriorated and he was admitted to the ICU for CPAP, and metaraminol for his hypotension. An initial FUSIC heart scan did not show any signs of ventricular failure. In fact, the heart was hyperdynamic which was more consistent with sepsis. A lung ultrasound did however demonstrate large bilateral plural effusions and the significant pitting oedema of the lower limbs found on clinical examination still suggested a cardiac cause and so help was asked of an advanced level operator. A review of the images and a repeat scan revealed a severe prolapse of the posterior mitral valve leaflet with free, eccentric mitral regurgitation. The leaflet prolapse was not visible on the 1st set of images and was only discovered by more comprehensive scanning. The patient was reviewed by a cardiologist within 30 minutes and transfer to a tertiary centre for emergency mitral valve repair was arranged. Conclusion(s): Standard history, examination, and investigations of this patient led to a presumed diagnosis of ischaemic ventricular failure. While a basic heart ultrasound did not reveal the pathology, it did demonstrate signs not consistent with the suspected diagnosis prompting a request for a more comprehensive ultrasound assessment. This revealed the underlying pathology, significantly altering the patient's management. This was all done by intensive care clinicians at the bedside, significantly shortening the time to diagnosis and correct management. This case is a good example of why Intensive Care clinicians should be trained in point of care ultrasound at both basic and advanced levels.

Focused transoesophageal TOE (fTOE): A new accreditation pathway (2023)

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Type of publication:
Journal article

Author(s):
Rubino A.; Peck M.; *Miller A.; Edmiston T.; Klein A.A.; Orme R.; Sankar V.; Fletcher N.; O'Keeffe N.; Skinner H.

Citation:
Journal of the Intensive Care Society. Date of Publication: 2023 Nov;24(4):419-426

Abstract:
The concept of a focused ultrasound study to identify sources of haemodynamic instability has revolutionized patient care. Point-of-care ultrasound (POCUS) using transthoracic scanning protocols, such as FUSIC Heart, has empowered non-cardiologists to rapidly identify and treat the major causes of haemodynamic instability. There are, however, circumstances when a transoesphageal, rather than transthoracic approach, may be preferrable. Due to the close anatomical proximity between the oesophagus, stomach and heart, a transoesphageal echocardiogram (TOE) can potentially overcome many of the limitations encountered in patients with poor transthoracic ultrasound windows. These are typically patients with severe obesity, chest wall injuries, inability to lie in the left lateral decubitus position and those receiving high levels of positive airway pressure. In 2022, to provide all acute care practitioners with the opportunity to acquire competency in focused TOE, the Intensive Care Society (ICS) and Association of Anaesthetists (AA) launched a new accreditation pathway, known as Focused Transoesophageal Echo (fTOE). The aim of fTOE is to provide the practitioner with the necessary information to identify the aetiology of haemodynamic instability. Focused TOE can be taught in a shorter period of time than comprehensive and teaching programmes are achievable with support from cardiothoracic anaesthetists, intensivists and cardiologists. Registration for fTOE accreditation requires registration via the ICS website. Learning material include theoretical modules, clinical cases and multiple-choice questions. Fifty fTOE examinations are required for the logbook, and these must cover a range of pathology, including ventricular dysfunction, pericardial effusion, tamponade, pleural effusion and low preload. The final practical assessment may be undertaken when the supervisors deem the candidate's knowledge and skills consistent with that required for independent practice. After the practitioner has been accredited in fTOE, they must maintain knowledge and competence through relevant continuing medical education. Accreditation in fTOE represents a joint venture between the ICS and AA and is endorsed by Association of Cardiothoracic Anaesthesia and Critical care (ACTACC). The process is led by TOE experts, and represents a valuable expansion in the armamentarium of acute care practitioners to assess haemodynamically unstable patients.

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