German Version

Machine-Assisted Autotransfusion in Deployment Medicine – 
Future Option or Gimmick?

Andreas García Bardon^a, Christoph Jänig^a

^a Bundeswehr Central Hospital Koblenz, Department of Anesthesiology, Intensive Care, Emergency Care, and Pain Treatment

Summary

Blood and blood components are a limited yet indispensable resource in medical care, both in civilian and military contexts. NATO projections for large-scale combat operations estimate a transfusion medicine-relevant demand of up to 10,000 whole blood equivalents per week. Combined with potential logistical supply bottlenecks, there is a need to continuously develop strategies to reduce the consumption of donor blood in the sense of Patient Blood Management (PBM) and adapt them to the specific conditions of military deployment medicine. While preoperative anemia diagnostics play a minor role in the deployment country, the rational use of blood products and the minimization of blood loss through medical and technical measures are central elements of this concept.

A proven tool for reducing donor blood consumption is machine-assisted autotransfusion (MAT). In addition to classic centrifugal systems (e.g., Cell Saver, CATSmart), HemoClear^®, a novel microfiltration-based method, is available, which operates entirely without electrical power and is gravity-driven. The system is lightweight, portable, designed as a disposable set, and ready for use quickly. In a closed loop, wound blood is filtered, washed, and processed into an erythrocyte suspension with a hematocrit of 50–60%. Unlike conventional MAT systems, HemoClear^® also allows significant recovery of functional platelets (on average 68%).

Initial in vitro data show a comparable erythrocyte concentration to the XTRA™ system and a reduction in dissolved plasma components (C3, C4, D-Dimer) by ≥ 90%. The hemolysis rate is 4.89%, higher than that of centrifugal systems (Ø 0.4%). The studies published so far originate exclusively from the manufacturer’s environment; reliable, independent clinical data are lacking. Therefore, a conclusive assessment of its suitability for military casualty care is not possible. Further investigations into the safety, effectiveness, and practicability of the method in the operational context are required.

Keywords: Autotransfusion, Patient Blood Management, Blood Supply, War, HemoClear, Microfiltration

Introduction and Background

Blood and blood components are already a scarce medical resource under regular supply conditions. According to the 21st Hemotherapy Report of the Paul Ehrlich Institute, 3,515,704 erythrocyte concentrates were distributed in Germany in 2021, of which 3,240,536 units were actually transfused [4]. These figures demonstrate that blood consumption in civilian care is already at the upper limit of what can be continuously covered by donor blood.

Blood Products – A Critical Bottleneck Resource

For military mass casualty scenarios – such as in the context of national and alliance defense or so-called Large Scale Combat Operations – NATO forecasts a significantly increased demand. A weekly requirement of up to 10,000 whole blood equivalents (WBE) is anticipated. It is assumed that about 20% of all hospitalized casualties will require blood products. The average need for these patients is 8 WBE per person [7]. From this, a requirement of 160 WBE for 100 casualties arises – equivalent to 160 erythrocyte concentrates (EC), 160 fresh frozen plasmas (FFP), 40 cryoprecipitates, and 40 platelet concentrates.

These figures vividly illustrate that blood products can quickly become critical bottlenecks in deployment scenarios. Logistical challenges, such as temperature-controlled transport, limited shelf life, or infrastructural disruptions, further exacerbate this problem. Against this backdrop, the concept of patient blood management (PBM) is gaining importance in optimizing the handling of available blood products and reducing the overall consumption of donor blood.

Patient Blood Management

The WHO called for the nationwide introduction of PBM programs in a 2011 policy paper to ensure safe, efficient, and resource-conserving handling of blood products [10]. PBM is based on three central pillars (Figure 1):

1. the rational use of blood products,
2. the minimization of blood loss through surgical, pharmacological, and organizational measures, and
3. the early detection and treatment of preoperative anemia [5].

Fig. 1: Schematic representation of the three central pillars of Patient Blood Management (PBM): The concept aims at a structured, evidence-based, and resource-conserving handling of blood products. It includes (1) early detection and therapy of anemia with potential postponement of elective interventions, (2) the rational use of blood products based on explicit indications, and (3) the consistent minimization of blood loss through operative and organizational measures. The WHO recommended the model as an international standard of care in 2011.

Reduction of Blood Loss

In the military medical context, the second pillar—the reduction of blood loss—gains relevance. Tourniquets, rapid prehospital hemorrhage control, targeted use of hemostatic drugs like tranexamic acid or calcium, and structured transfusion algorithms are established components of modern battlefield medicine. The application of procedures for the recovery of autologous blood, i.e., the immediate reinfusion of one’s blood loss, is increasingly coming into focus.

Rational and Indication-Appropriate Use of Blood Products

The first pillar of PBM, the rational and indication-appropriate use of blood products, remains fundamental. Recently, whole blood has been experiencing a renaissance in treating severely bleeding patients. Several studies demonstrate that using Fresh Whole Blood (FWB) in massive hemorrhage reduces the consumption of individual blood components and positively affects survival [3]. Integrating whole blood into deployment medical care models, such as through Walking Blood Bank concepts, is increasingly the subject of operational planning.

Perioperative Anemia Management

The third pillar—perioperative anemia management is subordinate to deployment due to the lack of elective interventions. Nevertheless, it should be given greater consideration in the home country. Early detection and, if necessary, treatment of existing anemia before a planned transfer can help make casualties more resilient to blood loss. In addition, elective interventions can be conducted with reduced donor blood consumption domestically, reducing the general consumption of blood products and freeing up capacity for deployment care.

Autologous Hemotherapy in Deployment?

In the context of these developments, the question arises whether established procedures of autologous hemotherapy, as they have been used in civilian hospitals for years, are also practicable under deployment conditions. Systems for machine-assisted autotransfusion (MAT), such as those used in elective surgical procedures, fundamentally offer the potential to reduce the need for donor blood. However, their application in the military context has so far been limited by size, weight, power dependency, and logistical complexity.

With the HemoClear^® system, a novel approach is now available that addresses these limitations. It is a microfiltration-based system for autologous blood processing that operates entirely gravity-driven and without electrical power. The disposable system is compact, lightweight (< 1 kg), easy to set up, and explicitly designed for resource-limited environments, such as those regularly encountered in military deployments.

This article aims to present the HemoClear^® system in detail and critically evaluate the current evidence, with special consideration of possible application scenarios in military casualty care.

Methods of Autologous Blood Transfusion

Machine-assisted autotransfusion (MAT) is a procedure for the recovery, processing, and retransfusion of autologous blood. It is classified as a permission-free measure under the German Medical Association for Hemotherapy guidelines, provided it is performed under direct medical responsibility and exclusively for personal application to the respective patient (§13 Abs. 2b Arzneimittelgesetz [2]). The application primarily encompasses intra- and postoperative situations where wound or drainage blood is converted into a washed erythrocyte suspension and retransfused to the patient.

Technical Process of MAT

The technical process is divided into three consecutive steps:

• Initially, blood is extracted directly from the surgical field using an operative suction device and protected from coagulation by adding an anticoagulant.
• Subsequently, it is collected and temporarily stored in a sterile reservoir.
• After reaching a sufficient volume, the machine processing begins with removing unwanted components and producing a transfusion-ready erythrocyte suspension.

Traditionally, two technically different systems are used in machine-assisted autotransfusion:

• discontinuous systems, as used in the Cell Saver^® (Haemonetics, USA) with the so-called Latham bowl, and
• continuously operating systems like the CATSmart^® (Fresenius Kabi, Germany).

Discontinuous System

The discontinuous system operates in sequential process steps: first, the wound blood is collected, then centrifuged, and finally, the cell concentrate bag is emptied. The centrifugation is carried out at a speed of about 5,650 rpm in a rotating centrifuge chamber (Latham bowl). Due to the resulting centrifugal force, the heavier erythrocytes are deposited on the bowl’s outer wall. At the same time, lighter components such as plasma, free hemoglobin, and cell debris rise and are drained into a waste bag.

After reaching a defined fill volume, the washing process begins, during which a specified amount of isotonic saline solution is used to remove further unwanted components. The processed erythrocyte suspension is then collected and ready for retransfusion. Due to its sequential operating principle, this procedure is exceptionally efficient for larger blood volumes but requires a particular minimum fill volume before the processing can begin.

Continuous System

In contrast, the continuously operating system allows for the ongoing processing of smaller blood volumes starting at about 30 ml. In the CATSmart^®, separation occurs via a rotating washing chamber with a spiral channel, operated at approximately 2,100 rpm, equivalent to a centrifugal acceleration of about 490 G. The blood to be processed is introduced at the inner edge of the channel and radially forced outward under centrifugal influence. The heavier erythrocytes settle on the outer side of the channel, while lighter plasma components and cell debris flow inward and are directed into the waste bag via a separate system. Washing coincides with introducing isotonic saline solution in the opposite direction. The continuous mode of operation enables nearly uninterrupted supply, especially in situations with unpredictable or intermittent blood loss. The manufacturer reported the effectiveness of plasma and fat elimination to be over 99% [6][11].

Advantages and Disadvantages of MAT Systems

Both the discontinuous and continuous MAT systems are characterized by high processing quality but are limited in terms of mobility and deployment flexibility. The devices are comparatively large, heavy, and designed for use in clinical settings. The Cell Saver^® system, for example, weighs over 20 kg, including accessories, and requires a stable power supply and sufficient space for setup and operation. The CATSmart^® system is also intended for stationary use and requires electrical power to operate the centrifuge and control the processing units. Application outside of established infrastructural frameworks – such as in tactical military operations or resource-poor regions – is thus only possible to a limited extent or not at all. This significantly limits the utility of both systems in situations with restricted logistical support.

Microfiltration – An Alternative?

With HemoClear^® (HemoClear BV, Netherlands), a portable, microfiltration-based system for autologous blood processing is available, and it operates entirely without electrical power (Figure 2). It was specifically designed for use under infrastructurally limited conditions, such as in regions without a stable power supply or in preclinical, military, and disaster medical scenarios. The entire system is designed as a disposable set, delivered in compact packaging, and can be set up by medical personnel within minutes. It weighs less than one kilogram in a ready-to-use state and can be easily transported in a backpack.

Fig. 2: Schematic representation of the HemoClear® system for gravity-based autologous blood processing (top left: collected blood in the collection bag; top right: isotonic saline solution (NaCl 0.9%) for rinsing):

The blood flows through a multi-layered microfiltration module, where erythrocytes and platelets are retained, and plasma components, leukocytes, and cell debris are filtered out. The washed cells are initially collected in the lower retransfusion bag. For effective washing, the process is conducted twice. The retransfusion bag is hung back over the filter system after the first pass, allowing gravity to return the blood to the upper bag, and the washing process can be repeated. Bottom right: Drainage of the filtrate into a separate waste bag. The system operates entirely without power supply. (Image: ©HemoClear)

Filtration by Gravity

The function is based on purely gravity-driven filtration through a multi-layered, semipermeable filter membrane. The wound or drainage blood is collected through a tubing system from an inlet bag and sent into the filter unit. The membrane structure separates erythrocytes and platelets from low-molecular-weight plasma components, leukocytes, cell debris, and dissolved inflammatory mediators. A subsequent washing process with isotonic saline solution removes remaining residues, and the erythrocytes are resuspended. The end product is a transfusion-ready erythrocyte suspension with a 50–60% hematocrit. The entire process takes approximately 25 to 30 minutes. A significant difference from conventional, centrifugal-based MAT systems is the simultaneous recovery of functional platelets, which could provide a potential advantage, especially in environments with limited availability of blood products.

Study Situation on the HemoClear^® System

In a manufacturer-initiated in vitro study, HemoClear^® was compared with the centrifugal autotransfusion system XTRA™. Both systems achieved comparable erythrocyte concentrations, with HemoClear® additionally enabling a reduction of complement factors C3 and C4 and D-Dimer by ≥ 90% [8]. While the overall elimination of dissolved plasma components was higher with the XTRA™ system, the authors attested that clinically acceptable blood quality was achieved with the HemoClear® method. The potential applicability in resource-limited contexts where classic, power-dependent cell separation devices are unavailable or impractical was highlighted as particularly advantageous.

The literature reports a hemolysis rate of about 0.4% for conventional MAT and 4.89% for HemoClear® [1]. However, the system enables substantial recovery of functional platelets with an average rate of 68% (± 10%), a functional difference from conventional methods [9].

The studies published on HemoClear® are limited in number and originate exclusively from the manufacturer’s environment. Independent, particularly clinical studies to evaluate the system’s effectiveness, safety, and practicability in real application scenarios are currently lacking.

Fig. 3: Application of the HemoClear® system in a simulated military medical station under field conditions: The setup of the system with blood and rinsing solution (NaCl 0.9%) at the top, the central microfiltration module, and the collection bag for washed erythrocytes is clearly visible. The operation is entirely gravity-controlled and without external power supply. (Image: ©HemoClear)

Conclusion

Blood and blood components are already a limited resource under current conditions, both in civilian and military areas, yet they are simultaneously indispensable for fulfilling the medical mission. A pre-planned concept for patient blood management and deployment medicine is essential. The necessity for alternative blood acquisition methods is increasingly evident in the context of potential “large-scale Combat Operations” with abruptly increasing demand and limited logistical supply.

HemoClear® offers a potential solution: The system is compact, mobile, and independent of an external power supply. Moreover, it allows the recovery of erythrocytes and platelets, which could prospectively contribute to closing a previously existing supply gap.

However, the data available so far are based exclusively on manufacturer-associated investigations. A clinical evaluation of the system’s safety and effectiveness is impossible without independent, methodologically robust studies. Further scientific investigations are, therefore, essential before potential integration into the armed forces’ medical capability profile.

References

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11. Seyfried TF, Gruber M, Pawlik MT et al.: A new approach for fat removal in a discontinuous autotransfusion device-concept and evaluation. Vox Sang 2017; 112(8): 759-766. read more

Manuscript Data

Citation

García Bardon A, Jänig C: Machine-Assisted Autotransfusion in Emergency Medicine – Future Option or Gimmick? WMM 2025; 69(6E): 7.

DOI: https://doi.org/10.48701/opus4-505

For the Authors

Commander (Navy MC) Dr. Andreas Garcia Bardon, MD

Bundeswehr Central Hospital Koblenz

Department of Anesthesiology, Intensive Care, Emergency Care, Pain Treatment

Rübenacher Str. 170, D-56072 Koblenz

E-Mail: andreasgarciabardon@bundeswehr.org