Use of a Centrifugal Vortex Blood Pump and Heparin-Bonded Circuit for Extracorporeal Rewarming of Severe Hypothermia in Acutely Injured and Coagulopathic Patients

Extracorporeal life support in trauma: Indications and techniques

BACKGROUND

Clarity about indications and techniques in extracorporeal life support (ECLS) in trauma is essential for timely and effective deployment, and to ensure good stewardship of an important resource. Extracorporeal life support deployments in a tertiary trauma center were reviewed to understand the indications, strategies, and tactics of ECLS in trauma.

METHODS

The provincial trauma registry was used to identify patients who received ECLS at a Level I trauma center and ECLS organization-accredited site between January 2014 and February 2021. Charts were reviewed for indications, technical factors, and outcomes following ECLS deployment. Based on this data, consensus around indications and techniques for ECLS in trauma was reached and refined by a multidisciplinary team discussion.

RESULTS

A total of 25 patients underwent ECLS as part of a comprehensive trauma resuscitation strategy. Eighteen patients underwent venovenous ECLS and seven received venoarterial ECLS. Nineteen patients survived the ECLS run, of which 15 survived to discharge. Four patients developed vascular injuries secondary to cannula insertion while four patients developed circuit clots. On multidisciplinary consensus, three broad indications for ECLS and their respective techniques were described: gas exchange for lung injury, extended damage control for severe injuries associated with the lethal triad, and circulatory support for cardiogenic shock or hypothermia.

CONCLUSION

The three broad indications for ECLS in trauma (gas exchange, extended damage control and circulatory support) require specific advanced planning and standardization of corresponding techniques (cannulation, circuit configuration, anticoagulation, and duration). When appropriately and effectively integrated into the trauma response, ECLS can extend the damage control paradigm to enable the management of complex multisystem injuries.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level IV.

Animal blood in translational research: How to adjust animal blood viscosity to the human standard

Animal blood is used in mock circulations or in forensic bloodstain pattern analysis. Blood viscosity is important in these settings as it determines the driving pressure through biomedical devices and the shape of the bloodstain. However, animal blood can never exactly mimic human blood due to erythrocyte properties differing among species. This results in the species-specific shear thinning behavior of blood suspensions, and it is therefore not enough to adjust the hematocrit of an animal blood sample to mimic the behavior of human blood over the entire range of shear rates that are present in the body. In order to optimize experiments that require animal blood, we need models to adapt the blood samples. We here offer mathematical models derived for each species using a multi linear regression approach to describe the influence of shear rate, hematocrit, and temperature on blood viscosity. Results show that pig blood cannot be recommended for experiments at low flow conditions (<200 s-1 ) even though erythrocyte properties are similar in pigs and humans. However, pig blood mimics human blood excellently at high flow condition. Horse blood is unsuitable as experimental model in this regard. For several studied conditions, sheep blood was the closest match to human blood viscosity among the tested species.

Use of an intravascular temperature control catheter for rewarming of hypothermic trauma patients with ongoing hemorrhagic shock after combined damage control thoracotomy and laparotomy: A case series

BACKGROUND

Correction of hypothermia is a key component of the resuscitation of critically injured patients with hemorrhagic shock who require damage control surgery. External rewarming methods may not be sufficient in this population, while extracorporeal techniques lack widespread feasibility. Intravascular catheter-based temperature modulation is increasingly being employed in different critically ill patient populations but has not been described as part of a damage control resuscitation strategy in trauma patients.

METHODS

We retrospectively reviewed the medical records of all patients admitted to our multi-trauma intensive care unit from July 1, 2015 - December 31, 2017 in whom an intravascular temperature control catheter (IVTCC) was employed for rewarming from hypothermia during the immediate postoperative resuscitation of continued hemorrhage after undergoing combined damage control thoracotomy and laparotomy for trauma. All patients received baseline treatment with active external rewarming modalities and inline fluid/blood warmers. Core temperature values over the first 24 h of hospital admission were analyzed. Efficacy (rewarming rate) and safety (associated adverse events) of the IVTCC system were determined.

RESULTS

Three patients (age 22 ± 4.6, 100% male, 100% torso gunshot wounds with prehospital cardiac arrest) meeting the inclusion criteria were treated with the IVTCC system during the study period. Temperature at the start of rewarming using the IVTCC ranged from 30.1 to 35.5 °C. Despite ongoing severe hemorrhagic shock (24-hour ICU blood product requirement: 104 ± 44 units), a mean rewarming rate of 1.04 ± 0.63°C/hour was achieved. One patient suffered an uncomplicated catheter-associated deep vein thrombosis. Two of the 3 patients survived to hospital discharge with intact cognitive function.

CONCLUSIONS

Use of an IVTCC may be a minimally-invasive, practical, and effective method for rewarming critically ill trauma patients with ongoing hemorrhagic shock after multi-cavitary damage control surgery. Further studies are needed to compare this technology with currently available rewarming methods.

Extracorporeal Rewarming From Accidental Hypothermia of Patient With Suspected Trauma

The use of extracorporeal membrane oxygenation is a new approach to rewarming patients with severe hypothermia and hemodynamic instability. There are, however, many questions regarding qualification for this technique in case of suspected or confirmed trauma.A male with confirmed accidental hypothermia (25°C) and after successful cardiopulmonary resuscitation from in-hospital cardiac arrest was subjected to a protocol of extracorporeal rewarming from profound hypothermia. Because of unclear history, a full trauma computed tomography was performed that showed pericerebral hematoma and signs of previously undergone right craniotomy, multiple right-sided rib fractures and the presence of intraperitoneal fluid. Based on repeated imaging and specialist consultation, no life-threatening injuries were identified and rewarming with extracorporeal membrane oxygenation was safely performed. In a year follow-up, the patient was found to be alive, with no neurologic deficits.Although this case highlights the first successful utilization of extracorporeal rewarming in a trauma patient at our center there are several limitations to its widespread use.

[Management of severe accidental hypothermia]

Accidental hypothermia is an environmental condition with basic principles of classification and resuscitation that apply to mountain, sea or urban scenarios. Along with coagulopathy and acidosis, hypothermia belongs to the lethal triad of trauma victims requiring critical care. A customized healthcare chain is involved in its management, extending from on site assistance to intensive care, cardiac surgery and/or the extracorporeal circulation protocols. A good classification of the degree of hypothermia preceding admission contributes to improve management and avoids inappropriate referrals between hospitals. The most important issue is to admit hypothermia victims in asystolia or ventricular fibrillation to those hospitals equipped with the medical technology which these special clinical scenarios require. This study attempts to establish the foundations for optimum management of accidental hypothermia from first emergency care on site to treatment in hospital including, resuscitation and rewarming with extracorporeal circulation.

Efficacy of portable and percutaneous cardiopulmonary bypass rewarming versus that of conventional internal rewarming for patients with accidental deep hypothermia

OBJECTIVE

Since 2001, at our institution, a portable and percutaneous cardiopulmonary bypass system has been used for rewarming of patients with accidental deep hypothermia. Before 2001, a conventional internal rewarming technique was used. The aim of this research is to examine the efficacy of portable and percutaneous cardiopulmonary bypass for rewarming of patients with accidental severe hypothermia and compare it with that of conventional rewarming methods.

DESIGN

Historical study.

SETTING

The exclusive emergency medical center and trauma center level 1 in Western Kanagawa, Japan.

PATIENTS

From April 1992 to March 2009, 70 patients with accidental deep hypothermia (core temperature <28°C) were transferred to our hospital. Two patients presented with intracranial hemorrhage on initial head computed tomography scans. These two patients were excluded because each required an emergency operation. Therefore, 68 patients were included in this study. We compared patients' clinical characteristics and outcomes. The parameters included the following: sex, age, vital signs on arrival to our hospital (Glasgow coma Scale scores, systolic blood pressure, heart rate, respiratory rate, core temperature), electrocardiogram on arrival to our hospital, rewarming speed, time of rewarming until 34°C was reached, ventricular fibrillation occurrence rate during rewarming, cause of cold environmental exposure, Glasgow Outcome Scale scores, and mortality. In addition, we divided the conventional and portable and percutaneous cardiopulmonary bypass rewarming groups into two categories depending on whether cardiopulmonary arrest occurred on arrival to our hospital. We also compared the survival rate and average Glasgow Outcome Scale scores for each group.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients' clinical backgrounds did not differ significantly between the conventional and portable and percutaneous cardiopulmonary bypass rewarming groups. Glasgow Outcome Scale scores and survival rates of the portable and percutaneous cardiopulmonary bypass rewarming group patients, irrespective of whether cardiopulmonary arrest was experienced on arrival to our hospital, were significantly higher than those of the conventional rewarming group.

CONCLUSIONS

Portable and percutaneous cardiopulmonary bypass rewarming can improve the mortality rates and Glasgow Outcome Scale scores of accidental deep hypothermia patients.

Severe traumatic injury during long duration spaceflight: Light years beyond ATLS

Traumatic injury strikes unexpectedly among the healthiest members of the human population, and has been an inevitable companion of exploration throughout history. In space flight beyond the Earth's orbit, NASA considers trauma to be the highest level of concern regarding the probable incidence versus impact on mission and health. Because of limited resources, medical care will have to focus on the conditions most likely to occur, as well as those with the most significant impact on the crew and mission. Although the relative risk of disabling injuries is significantly higher than traumatic deaths on earth, either issue would have catastrophic implications during space flight. As a result this review focuses on serious life-threatening injuries during space flight as determined by a NASA consensus conference attended by experts in all aspects of injury and space flight.In addition to discussing the impact of various mission profiles on the risk of injury, this manuscript outlines all issues relevant to trauma during space flight. These include the epidemiology of trauma, the pathophysiology of injury during weightlessness, pre-hospital issues, novel technologies, the concept of a space surgeon, appropriate training for a space physician, resuscitation of injured astronauts, hemorrhage control (cavitary and external), surgery in space (open and minimally invasive), postoperative care, vascular access, interventional radiology and pharmacology.Given the risks and isolation inherent in long duration space flight, a well trained surgeon and/or surgical capability will be required onboard any exploration vessel. More specifically, a broadly-trained surgically capable emergency/critical care specialist with innate capabilities to problem-solve and improvise would be desirable. It will be the ultimate remote setting, and hopefully one in which the most advanced of our societies' technologies can be pre-positioned to safeguard precious astronaut lives. Like so many previous space-related technologies, these developments will also greatly improve terrestrial care on earth.

The efficacy of rewarming with a portable and percutaneous cardiopulmonary bypass system in accidental deep hypothermia patients with hemodynamic instability

OBJECTIVE

Accidental deep hypothermia (ADH)--a condition in which the core body temperature is less than 28 degrees C--is a medical emergency; the mortality rates for ADH remain high. The efficacy of cardiopulmonary bypass (CPB) rewarming has been proved in ADH patients with cardiopulmonary arrest; however, its efficacy in the ADH patients without cardiopulmonary arrest remains controversial. In our study, we evaluated the efficacy of portable percutaneous cardiopulmonary bypass (PPCPB) for rewarming and providing cardiovascular support in the hemodynamically unstable ADH patients without cardiopulmonary arrest.

METHODS

Between April 2001 and March 2006, we performed a retrospective study at Tokai University, Kanagawa, Japan. We studied 24 ADH patients without cardiopulmonary arrest (male:female ratio, 15:9; mean age, 68.5 +/- 12.9 years) with hemodynamic instability who had not developed intracranial hemorrhage. We evaluated the efficacy of PPCPB rewarming by estimating the mean time of initiation of PPCPB after admission, rewarming speed, the success rate of rewarming, the rate of weaning from PPCPB, the incidence of ventricular fibrillation (Vf) during rewarming, complications associated with PPCPB, mortality rate, and the Glasgow Outcome Scale (GOS) scores of the patients who survived.

RESULTS

The mean time of initiation of PPCPB after admission was 41.9 +/- 7.9 minutes. The rewarming speed was 4.0 +/- 1.5 degrees C/h. A 100% success rate was achieved after the rewarming procedure, whereas the rate of weaning from PPCPB was 91.7%. Vf during rewarming developed in one case; however, electrical defibrillation was possible. No direct complications of PPCPB were observed. The mortality rate was 12.5% (3/24). The GOS scores of the patients who survived were as follows: 5 points, 17 cases; 4 points, 3 cases; and 3 points, 1 case.

CONCLUSION

PPCPB rewarming is a clinically efficacious procedure for rewarming and providing cardiovascular support in hemodynamically unstable ADH patients without cardiopulmonary arrest who have not developed intracranial hemorrhage.

Hypothermia in the geriatric population

Hypothermia is common in the geriatric population and its significance perhaps under-recognized. Hypothermia is associated with substantial morbidity and fatality, but to some extent is preventable provided caregivers and providers of healthcare to older adults adopt preventive measures to lower its occurrence. Hypothermia occurs in both cold and warm settings; its pathogenesis involves alterations in the age-related physiology of thermoregulation, along with a variable combination of environmental factors, disease processes and medications, many of which are recognizable. Once diagnosed, treatment must be prompt and aggressive, and must consider several options for rewarming. Education of healthcare providers regarding early recognition of hypothermia and a better understanding of preventive and treatment measures will undoubtedly lower complications of hypothermia in affected elderly.

Active internal re-warming using a centrifugal pump and heat exchanger following haemorrhagic shock, surgical trauma and hypothermia in a porcine model

BACKGROUND

The centrifugal vortex blood pump (CVBP) using heparin-bonded circuitry allows re-warming of hypothermic trauma patients without anticoagulation. Study objectives were to confirm efficacy, and to characterise the physiology of CVBP re-warming in a porcine model.

METHODS

Sixteen pigs were randomised to conventional or CVBP re-warming. They were bled to a mean arterial pressure of 30 mmHg and cooled to 29 degrees C. A physiological analysis was recorded during resuscitation to normo-tension and re-warming back to 37 degrees C.

RESULTS

CVBP animals re-warmed significantly faster: 85.0+16.4 min versus 217.4+49.3 min (p<0.0001). Activated clotting time was significantly elevated in both groups at 29 degrees C with a marked trend to normalise faster in CVBP pigs. The peak cardiac index (CI) was significantly lower (1.14+0.68 versus 4.83+1.50 L/(min m2), while the systemic vascular resistance (SVR) was significantly higher (4239.9+1173.0 versus 1472.6+451.2 dyn x S x m2/cm5) with CVBP (p<0.001).

CONCLUSION

CVBP is simple and very effective at re-warming hypothermic animals and may also reverse coagulopathy more quickly. Physiological derangements of elevated SVR and diminished CI require further study to elaborate underlying aetiology, and define optimal re-warming strategies.

Hypothermia and injury

PURPOSE OF REVIEW

Recent studies demonstrating that mild therapeutic hypothermia can improve the outcome from several ischemic and traumatic insults have led to increased interest in the potential benefits of hypothermia after injury. Previous clinical studies, however, have suggested that hypothermia is detrimental to trauma patients. This most likely is a result of differences in the physiologic effects between uncontrolled exposure hypothermia and controlled therapeutic hypothermia. The laboratory and clinical data regarding traumatic hemorrhagic shock and hypothermia are presented, as well as a novel approach to the patient with exsanguinating trauma: suspended animation. Therapeutic hypothermia for traumatic brain injury is discussed.

RECENT FINDINGS

Laboratory studies of hemorrhagic shock demonstrate improved survival with mild hypothermia. For the first time, this was shown in a study in a large animal outcome model of hemorrhagic shock with trauma and intensive care. Because clinical studies continue to suggest an association between the development of hypothermia and worse outcomes in trauma patients, clinicians are continuing efforts to prevent and treat hypothermia. For exsanguination cardiac arrest, laboratory studies have demonstrated the feasibility of inducing hypothermic preservation via a rapid aortic flush (suspended animation). For traumatic brain injury, the most recent clinical trial did not show an overall benefit, but it seems that patients who arrive mildly hypothermic have better outcomes if hypothermia is maintained.

SUMMARY

The dichotomy between laboratory findings that show a benefit of hypothermia and clinical findings that suggest detrimental effects remains difficult to explain. For now, preventing hypothermia remains prudent. Suspended animation seems promising for patients with exsanguinating trauma. Clinical trials of mild hypothermia during hemorrhagic shock and suspended animation for exsanguination are indicated. Clinical trials of hypothermia for traumatic brain injury are in progress.

Damage control surgery and the abdomen

There is a complex interplay between primary injury, particularly major abdominal injury in the multi-system trauma patient, and secondary injury, which relate to patient physiology, decision making and surgical technique. Analysis of outcomes is further confounded by the variety of surgical techniques used. The challenge is to match the correct operation, for a critically injured patient, with the patient's physiology. Excellence in general surgery does not equate with excellence in trauma surgery, and a clear understanding of damage control is essential.