HemaShock® Safety

Safety of HemaShock® – Effect on Limbs

Stopping arterial blood supply to a limb does not cause sustained injury due to limb ischemia if limited to 120 minutes (Klenermann L. The Tourniquet Manual)

This practice is used daily in orthopedics (about 16,000 cases/day) by using an Esmarch bandage, pneumatic tourniquet or the HemaClear®.

Emergency arterial tourniquets are recommended for stopping blood loss in severe limb injuries and have been recently used successfully in several hundreds of US soldiers in combat.

Time Limits

The effects of ischemia on a tissue vary depending on the oxygen and high energy compounds stores, the level of activity o, tissue, which determine the oxygen and metabolites consumption and the threshold for functionality cessation. In addition, the tissue capacity to generate ATP from anaerobic metabolism is important.

There is a large variability in all parameters between tissues. For example, the cardiac muscle has nearly no reserves of energy/oxygen stores. It extracts more oxygen from the blood flowing through the coronary circulation than any other tissue and is in constant high demand for oxygen and metabolites. The brain also lacks storage and is working hard even when seems idle. The brain has a very low tolerance for low oxygen supply and functionality will decrease or stop very soon after blood supply stops or becomes critically low. Nerves (axons), on the other hand, have little oxygen consumption, particularly when not activated.

Muscles, skin, fat and bone tissues, on the other hand, are much more resistive to blocking of the blood flow into them. Muscles are used to consuming more energy than is supplied to them. Energy is stored in the form of Creatine Phosphate which can easily transfer a phosphate to an ADP molecule and generate an ATP. In addition, oxygen is stored in the muscle as bound to a Heme component of the Myoglobin which can dissociate and become available when the tissue PO2 falls below 10 or so mm Hg. Also, there are some ATP stores available. Once the muscle PO2 falls sufficiently, glycogen stores are converted to glucose and anaerobic metabolism becomes active.

It should be noted that all the enzyme systems that are needed for these metabolic pathways are readily expressed in muscles. They provide energy when the muscles are active, and are available to prevent ischemic injury for quite some time.

It is generally accepted that blocking the arterial blood flow into a limb is safe for at least two hours. Abstracts shown below are a few of many publications that studied this issue in animal and human experiments.

Use of Tourniquets in Emergency Medicine

Read more about the history and use of combat/emergency tourniquet.

The most recent war in Iraq was associated with a large number of injuries to soldiers. Dr. John Krahg and his associates from the US Army Institute of Surgical Research, Fort Sam Houston, TX diligently followed the outcome of the use of hundreds of tourniquets on hundreds of limbs. The abstracts from their published studies are copied herewith.

Tourniquets have been used in combat and emergency medicine for several hundred years. The indication has always been to stop arterial flow into the limb and by doing so, stop the hemorrhage from a limb injury.

The use of the HemaShock® also reduces the ratio of unstressed to stress vascular volume.

The clear conclusion is that the use of the tourniquet in combat limb injuries is safe and effective. Most tourniquets did not stay on the limb for more than 2 hours, but some did. Nevertheless, no limbs were lost because of tourniquet use. This recent experience with devices that apply sufficient pressure to occlude arterial flow into the limb is highly relevant to the use of the HemaShock®.

Extending HemaShock® Beyond the 2 Hours Limit

The time limit of 120 minutes for the continuous use of HemaShock® is based on the standard practice in orthopedic surgery and with the use of emergency/combat tourniquet.

In most instances this should be sufficient time to evacuate the patient to definitive care in a medically controlled environment, to establish the other measures needed to stabilize the patient (diagnostic tests, Surgical intervention if needed, IV fluids, blood, vasoactive drugs, antibiotics, steroids and the like), and to stabilize the patient’s hemodynamics.

However, sometimes 120 minutes are not enough, due to a variety of clinical and/or logistical reasons. In addition, the requirement that the HemaShock® be removed from the patient gradually, in small steps, while monitoring his/her blood pressure and other indicators of hemodynamics, will sometimes require more time. The question of “buying” additional time becomes crucial.

Extending the tourniquet time is discouraged.

Although the literature, including recommendations by authorities such as Mr. Leslie Klenerman from the UK, indicates that the use of a tourniquet for more than 2 hours (up to three hours) is not associated with irreversible injury to the limb, we do not recommend doing so, unless it is a clear case of “Life vs. Limb” condition with an explicit decision made by a competent physician.

The alternative is to apply a “rotating tourniquet” approach. It’s not unlike the old rotating (venous) tourniquet used in cases of severe Congestive Heart Failure before positive pressure ventilation became widely available. We propose removing HemaShock® from one leg while applying two child-size HemaShock® devices to the arms at about 90 minutes after onset.

About 30 minutes, re-apply a HemaShock® on the free leg while removing the HemaShock® from the second leg and from one or both arms. This process can be repeated while maintaining a very careful log of the duration of each limb blood flow occlusion.

This method can extend the duration of HemaShock® application for several hours if transport is very long or for other reasons.

Ischemia-Reperfusion & Time Interval Between HemaShock® Applications

The time interval from the removal of one HemaShock® and the application of another depends on the duration of the ischemia prior to the interval.

Studies in experimental animals show that after one hour of ischemia, 20 minutes are sufficient for recovery of standard bicarbonate, potassium and hydrogen ion levels in the tissues. (Klenerman L. et al.) Systemic and local effects of the application of a tourniquet. (Journal of Bone and Joint Surgery 1980; 62B: 385-388. [Also on page 31 of the Tourniquet Manual by Klenerman]). If the tourniquet is kept on the limb for 2 hours, the data in this study shows that 40 minutes are needed to fully recover HCO3-, K+, and H+ levels. By extrapolation, one may deduce that 30 minutes of recovery is required after 1.5 hours of blood flow occlusion. Combining these data render the Tang method reasonable, although prospective validation is indicated.

General Information About the Regulatory Status of HemaShock®

HemaShock® is intended for use in patients whose systolic blood pressure is pathologically low (i.e. less than 80 mm Hg in adults) due to Hemodynamic Shock or Circulatory (Cardiac) Arrest. HemaShock® shares technology with the Surgical Exsanguination Tourniquet manufactured by OHK as HemaClear® (www.HemaClear.com) which has been cleared for use in many countries around the world. The following is information on the regulatory status of the device in various countries. Should you have any questions, please contact us.

Europe
The device is classified as Class I, based on Annex IX, Rule 4 of the Medical Directive 93/42/EEC.

USA
The Surgical Exsanguination Tourniquet was cleared by the FDA in 2002. The HemaShock® FDA clearance needs a further submission.

Systemic and Local Effects of the Application of a Tourniquet [link]

J Bone Joint Surg Br. 1980 Aug; 62(3):385-8. KlenermanL, BiswasM, HulandsGH, Rhodes AM.

The effect of the application of a tourniquet to a limb and the release of the accumulated metabolites have been investigated with reference to the acid-base level in the blood from the limb and in the right atrium.

Investigations have been carried out experimentally in rhesus monkeys and observations have been made on patients undergoing reconstructive operations on the knee. The acidotic blood from the ischemic limb produces a little systemic effect. The limb recovers in approximately 40 minutes after a tourniquet has been in place for four hours. Three hours is recommended as a reasonable upper limit for the safe application of a pneumatic tourniquet.

The Effect of Pneumatic Tourniquets on the Ultrastructure of Skeletal Muscle [link]

J Bone Joint Surg Br. 1979 May;61-B(2):178-83. Patterson S, KlenermanL

Experiments have been carried out on rhesus monkeys to determine the effect of the application of a pneumatic tourniquet on the ultrastructure of the muscles of the lower limb. Tourniquets were applied for periods lasting between one and five hours. The changes in the muscle lying immediately under the cuff of the tourniquet were more marked than those observed in muscle distal to the cuff. Three hours appear to be close to the limit of the time that a muscle can resist the sustained compression of a tourniquet

Tourniquet Ischaemia – Clinical and Biochemical Observations [link]

Ann Chir Gynaecol. 1978;67(6):210-3. SantavirtaS, KausteA, RindellK

The duration of tourniquet ischaemia was recorded in 1000 consecutive operations on extremities under a bloodless field, the average ischaemia time was 74.11 +/-29.52 minutes. The duration of tourniquet ischaemia in meniscectomies was 58.47 +/- 15.91 minutes, in osteosynthesis of malleolar fractures 88.46 +/- 23.33 minutes and in operations for endoprosthetic replacement of the knee joint 131.19 +/- 11.24 minutes. In 85 cases the commonly accepted two hour limit for tourniquet time was exceeded without clinical complications. LDH and CPK levels in venous blood were studied in 15 operations. No significant changes were seen in LDH levels when recorded up to 24 hours following the release of the tourniquet. CPK levels increased significantly (p less than 0.05) and highly significantly (p less than 0.005) when measured three hours and 24 hours after the release of the tourniquet, respectively. The results of the study suggest that two hours of ischaemia of the extremities is relatively well tolerated.

Practical Use of Emergency Tourniquets to Stop Bleeding in Major Limb Trauma [link]

J Trauma. 2008 Feb;64(2 Suppl):S38-49; discussion S49-50. KraghJF Jr, Walters TJ, Baer DG, Fox CJ, Wade CE, Salinas J, Holcomb JB. Source: US Army Institute of Surgical Research, Fort Sam Houston, TX 78234-6315, USA. john.kragh@amedd.army.mil

BACKGROUND

Previously we showed that tourniquets were lifesaving devices in the current war. Few studies, however, describe their actual morbidity in combat casualties. The purpose of this study was to measure tourniquet use and complications.

METHODS

A prospective survey of casualties who required tourniquets was performed at a combat support hospital in Baghdad during 7 months in 2006. Patients were evaluated for tourniquet use, limb outcome, and morbidity. We identified potential morbidities from the literature and looked for them prospectively. The protocol was approved by the institutional review board.

RESULTS

The 232 patients had 428 tourniquets applied on 309 injured limbs. The most effective tourniquets were the Emergency Medical Tourniquet (92%) and the Combat Application Tourniquet (79%). Four patients (1.7%) sustained transient nerve palsy at the level of the tourniquet, whereas six had palsies at the wound level. No association was seen between tourniquet time and morbidity. There was no apparent association of total tourniquet time and morbidity (clots, myonecrosis, rigor, pain, palsies, renal failure, amputation, and fasciotomy). No amputations resulted solely from tourniquet use. However, six (2.6%) casualties with eight preexisting traumatic amputation injuries then had completion surgical amputations and also had tourniquets on for >2 hours.
The rate of limbs with fasciotomies with tourniquet time <or=2 hours was 28% (75 of 272) and >2 hours was 36% (9 of 25, p = 0.4).

CONCLUSIONS

Morbidity risk was low, and there was a positive risk-benefit ratio in light of the survival benefit. No limbs were lost because of tourniquet use, and tourniquet duration was not associated with increased morbidity. Education for early military tourniquet use should continue.

Prehospital Tourniquet use in Operation Iraqi Freedom: Effect on Hemorrhage Control and Outcomes [link]

J Trauma. 2008 Feb; 64(2 Suppl):S28-37; discussion S37.  BeekleyAC, SebestaJA, BlackbourneLH, Herbert GS, KauvarDS, Baer DG,
Walters TJ, MullenixPS, Holcomb JB; 31st Combat Support Hospital Research Group. Source Department of General Surgery, Madigan Army Medical Center, Fort Lewis, WA 98431-1100, USA. alec.beekley@us.army.mil

BACKGROUND

Up to 9% of casualties killed in action during the Vietnam War died from exsanguination from extremity injuries. Retrospective reviews of prehospital tourniquet use in World War II and by the Israeli Defense Forces revealed improvements in extremity hemorrhage control and very few adverse limb outcomes when tourniquet times are less than 6 hours.

HYPOTHESIS

We hypothesized that prehospital tourniquet use decreased hemorrhage from extremity injuries and saved lives, and was not associated with a substantial increase in adverse limb outcomes.

METHODS

This was an institutional review board-approved, retrospective review of the 31st combat support hospital for 1 year during Operation Iraqi Freedom. Inclusion criteria were any patient with a traumatic amputation, major extremity vascular injury, or documented prehospital tourniquet.

RESULTS

Among 3,444 total admissions, 165 patients met inclusion criteria. Sixty-seven patients had prehospital tourniquets (TK); 98 patients had severe extremity injuries but no prehospital tourniquet (No TK). Extremity Acute Injury Scores were the same (3.5 TK vs. 3.4 No TK) in both groups. Differences (p < 0.05) were noted in the numbers of patients with arm injuries (16.2% TK vs. 30.6% No TK), injuries requiring vascular reconstruction (29.9% TK vs. 52.5% No TK), traumatic amputations (41.8% TK vs. 26.3% No TK), and in those patients with adequate bleeding control on arrival (83% TK vs. 60% No TK). Secondary amputation rates (4 (6.0%) TK vs. 9 (9.1%) No TK); and mortality (3 (4.4%) TK vs. 4 (4.1%) No TK) did not differ. Tourniquet use was not deemed responsible for subsequent amputation in severely mangled extremities. Analysis revealed that four of seven deaths were potentially preventable with functionalprehospital tourniquet placement.

CONCLUSIONS

Prehospital tourniquet use was associated with improved hemorrhage control, particularly in the worse injured (Injury Severity Score >15) subset of patients. Fifty-seven percent of the deaths might have been prevented by earlier tourniquet use. There were no early adverse outcomes related to tourniquet use.

(Link: https://www.ncbi.nlm.nih.gov/pubmed/18376170)
J Trauma. 2008 Feb;64(2 Suppl):S38-49; discussion S49-50. KraghJF Jr, Walters TJ, Baer DG, Fox CJ, Wade CE, Salinas J, Holcomb JB. Source: US Army Institute of Surgical Research, Fort Sam Houston, TX 78234-6315, USA. john.kragh@amedd.army.mil

BACKGROUND

Previously we showed that tourniquets were lifesaving devices in the current war. Few studies, however, describe their actual morbidity in combat casualties. The purpose of this study was to measure tourniquet use and complications.

METHODS

A prospective survey of casualties who required tourniquets was performed at a combat support hospital in Baghdad during 7 months in 2006. Patients were evaluated for tourniquet use, limb outcome, and morbidity. We identified potential morbidities from the literature and looked for them prospectively. The protocol was approved by the institutional review board.

RESULTS

The 232 patients had 428 tourniquets applied on 309 injured limbs. The most effective tourniquets were the Emergency Medical Tourniquet (92%) and the Combat Application Tourniquet (79%). Four patients (1.7%) sustained transient nerve palsy at the level of the tourniquet, whereas six had palsies at the wound level. No association was seen between tourniquet time and morbidity. There was no apparent association of total tourniquet time and morbidity (clots, myonecrosis, rigor, pain, palsies, renal failure, amputation, and fasciotomy). No amputations resulted solely from tourniquet use. However, six (2.6%) casualties with eight preexisting traumatic amputation injuries then had completion surgical amputations and also had tourniquets on for >2 hours.
The rate of limbs with fasciotomies with tourniquet time <or=2 hours was 28% (75 of 272) and >2 hours was 36% (9 of 25, p = 0.4).

CONCLUSIONS

Morbidity risk was low, and there was a positive risk-benefit ratio in light of the survival benefit. No limbs were lost because of tourniquet use, and tourniquet duration was not associated with increased morbidity. Education for early military tourniquet use should continue.

Is MAST a Must?

Noam Gavriely MD, DSc
[Janna: Link to the pdf document “is mast a must?” ]

Survival with Emergency Tourniquet Use to Stop Bleeding in Major Limb Trauma [link]

Ann Surg. 2009 Jan;249(1):1-7. KraghJF Jr, Walters TJ, Baer DG, Fox CJ, Wade CE, Salinas J, Holcomb JB. Source: US Army Institute of Surgical Research, Fort Sam Houston, TX, USA.

OBJECTIVE

The purpose of this study was to determine if emergency tourniquet use saved lives.

BACKGROUND DATA

Tourniquets have been proposed as lifesaving devices in the current war and are now issued to all soldiers. Few studies, however, describe their actual use in combat casualties.

METHODS

A prospective survey of injured who required tourniquets was performed over 7 months in 2006 (NCT00517166 at ClinicalTrials.gov). Follow-up averaged 28 days. The study was at a combat support hospital in Baghdad. Among 2,838 injured and admitted civilian and military casualties with major limb trauma, 232 (8%) had 428 tourniquets applied on 309 injured limbs. We looked at emergency tourniquet use, and casualties were evaluated for shock (weak or absent radial pulse) and prehospital versus emergency department (ED) tourniquet use. We also looked at those casualties indicated for tourniquets but had none used. We assessed survival rates and limb outcome.

RESULTS

There were 31 deaths (13%). Tourniquet use when shock was absent was strongly associated with survival (90% vs. 10%; P < 0.001). Prehospital tourniquets were applied in 194 patients of which 22 died (11% mortality), whereas 38 patients had ED application of which 9 died (24% mortality; P = 0.05). The 5 casualties indicated for tourniquets but had none used had a survival rate of 0% versus 87% for those casualties with tourniquets used (P < 0.001). Four patients (1.7%) sustained transient nerve palsy at the level of the tourniquet. No amputations resulted solely from tourniquet use.

CONCLUSIONS

Tourniquet use when shock was absent was strongly associated with saved lives, and prehospital use was also strongly associated with lifesaving. No limbs were lost due to tourniquet use.

Education and fielding of prehospital tourniquets in the military environment should continue.

The Pneumatic Anti-Shock Garment (PASG), also called Medical (Military) Anti-Shock Trousers (MAST).

It is shown ready for use with the two leg compartments (on right) and the abdominal wrap (on left). The air bladders are connected to the foot pump (black circular element) and a gauge with a relief valve which limits the pressure to 104 mm Hg above ambient pressure.

The pressure during pumping up is distributed evenly and does not act from proximal to distal as required for displacing blood into the central circulation.

Comparison of HemaShock® & PASG/MAST

We developed the HemaShock®, an Auto-Transfusion tourniquet, which is an elastic torus with a long sleeve wrapped around it that, when applied to a limb, squeezes the blood away from the limb into the central circulation and blocks the re-entry of blood into it.

Below is an outline of the differences and similarities between our new approach to external counter-pressure and the current pneumatic anti-shock garments (PASG) including the MAST:

a. Auto-transfusion – in more than 150 journal papers that we collected and read on the PASG there was NOT even ONE study that demonstrated sustained auto-transfusion that was induced by the device. The HemaShock®, on the other hand, induced more than 1000 ml of auto-transfusion from the legs to the central circulation in our study, which is attached herein. This difference is due to the mode of pressure application sequence of the two devices: the HemaShock® applies the pressure from distal to proximal, while the PASG applies it to the lower body.

b. HemaShock® acts on the legs alone and does not interfere with blood flow to the abdominal organs, as does the PASG. As such, it does not cause ischemia of the gut and/or liver and does not impede their normal activity. We believe that the reason for the slight drop in lactic acid and CPK levels found in our study during HemaShock® application is actually due to elevated hepatic blood flow induced by the auto-transfusion.

c. Unlike the PASG, HemaShock® can be removed stepwise while monitoring the patient’s condition. It can easily be rolled down from thigh to knee level, each leg at a time and then down to the ankle. Any attempt to remove the PASG by slow deflation is bound to cause trapping of blood distal to the partially inflated abdominal compartment with pooling of venous blood. This venous occlusion effect of the partially inflated MAST actually removes blood from the central circulation. In addition, the pooled blood quickly becomes rich in Potassium, acids, and other toxic by-products of ischemia. When the pressure is completely released the blood outpours into the central circulation with negative effects on the heart and other essential organs. We believe that distal blood trapping is a major flaw in the design of the PASG, which is responsible, in large part, to the overall poor outcome of the PASG use. This problem is overcome by the HemaShock® design.

d. The effect of the HemaShock® can be titrated to maintain a desired BP of 90-100 mm Hg. This is done by selecting the number of limbs (1 – 4, including the arms) and the level of the elastic ring position on the limb. The ring can easily be rolled up and down to meet the needs of the patient’s treatment if so desired. This cannot be done with the PASG. Deflation of the PASG to less than the maximum pressure of 104 mm Hg in a patient whose systolic BP is higher than the PASG pressure causes arterial blood to escape beyond the proximal (abdominal) compartment. This blood gets trapped due to the venous occlusion effect of the partially inflated PASG. Re-inflation of the PASG pressure does not induce re-infusion of the trapped blood, particularly the blood pooled in the body segments not directly under the effect of the MAST cuffs (the genitals, the pelvis, etc.).

e. The HemaShock® is not different in essence from the method used in orthopedic surgery to maintain ‘bloodless’ surgical field. The extremity is tightly wrapped with an elastic strip followed by inflation of a pneumatic cuff at the proximal end of the limb. The cuff is typically inflated to 250 mm Hg. The current teaching is to keep the cuff inflated for not more than 2 hours, but there are animal studies that show that this period can be extended if the limb is hypothermic. This method is routinely used in almost every elective orthopedic procedure with a rate of complications reported to be one per 5000-8000, mostly transient paresis due to direct mechanical compression of the nerves beneath the occluding cuff. The HemaShock® pressure inside the limb is lower (130 mm Hg). The literature on clinical and animal studies with the orthopedic tourniquet does not mention any severe systemic effects during its use and/or after its removal. A detailed description and discussion of the orthopedic tourniquet method may be found in Canale TS. Campbell’s Operative Orthopaedics. 9th ed. St. Louis, Mosby 1998:30-31. Additional references will be provided upon request.

f. There are several technological differences between the PASG and the HemaShock®:

HemaShock® is much smaller (320 g per set of two vs. 4.5 kg) and occupies much less space.

HemaShock® is intended for single use, while the PASG is not.

Once HemaShock® is applied, the sleeve may be cut away to permit access to a wound if that is necessary. This is not possible with the PASG.

HemaShock® is not a pneumatic device. As such it is not affected by changes in ambient atmospheric pressure and/or temperature.

The HemaShock® cannot be removed inadvertently as was reported with the Velcro fasteners of some versions of the PASG.

Applying HemaShock® by one person is feasible, even during transport. Using the PASG usually requires a team of at least two men.
It takes 6-12 seconds to apply the HemaShock® to each limb. A trained team of medics can put the PASG on a patient within one minute, but then it takes 2-4 additional minutes to inflate it. A large study of MAST use showed an average of 5 minutes longer transport time in patients who were treated with MAST.

Training: use of the HemaShock® is simple, requires minimal training and can be applied by persons with no medical background. Safe application of the MAST requires several hours of training.

Cost:: HemaShock® cost is lower than that of the PASG.

Learn About HemaShock®

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