Martial arts technique for control of severe external bleeding

ObjectivesHaemorrhage control is a critical component of preventing traumatic death. Other than the battlefield, haemostatic devices, such as tourniquets or bandages, may not be available, allowing for significant avoidable blood loss. We hypothesised that compression of vascular pressure points using a position adapted from the martial art of Brazilian Jiu-Jitsu could be adapted to decrease blood flow velocity in major extremity arteries.MethodsKnee mount compression was applied to the shoulder, groin and abdomen of healthy adult volunteer research subjects from Seattle, Washington, USA, from March through May 2018. Mean arterial blood flow velocity (MAV) was measured using ultrasound in the brachial and femoral arteries before and after compression. A MAV decrease greater than 20% with compression was deemed clinically relevant.ResultsFor 11 subjects, median (IQR) MAV combining all anatomical locations tested was 29.2 (34.1, 24.1) cm/s at baseline and decreased to 3.3 (0, 19.1) cm/s during compression (Wilcoxon p<0.001). MAV was significantly decreased during compression for each individual anatomical position tested (Wilcoxon p≤0.004). Per cent (95% CI) MAV reduction was significantly greater than 20% for shoulder compression at 97.5%(94% to 100%) and groin compression at 78%(56% to 100%), but was not statistically greater for abdominal compression at 35%(12% to 57%). Complete vessel occlusion was most common with compression at the shoulder (73%), followed by groin (55%) and abdomen (9%) (χ² LR, p=0.018).ConclusionThe Brazilian Jiu-Jitsu knee mount position can significantly decrease blood flow in major arteries of the extremities. This technique may be useful for bleeding control after injury.

Novel Utilization of the Bridge during Weaning off Venoarterial ECMO: The Hoffman Clamp Method

Standard practice for weaning patients off venoarterial extracorporeal membrane oxygenation (ECMO) occurs by decreasing pump flows until idle flow is achieved. This method is limited in its use because it is difficult to assess a patient's true potential to successfully come off ECMO when supported by idle flow. We have developed a weaning technique that uses a Hoffman clamp on the bridge to decrease blood flow to the patient beyond idle flow. This method was used to wean eight patients from venoarterial ECMO. No patients weaned with this technique required emergent reinstitution of ECMO. The Hoffman clamp technique has allowed us to safely wean patients off ECMO support while maintaining integrity of the circuit.

Effect of spaceflight on the subcutaneous venoarteriolar reflex in the human lower leg

Whenever the legs are lowered in humans, a venoarteriolar reflex is activated by the hydrostatic distension of the venules. Through local axon reflexes, the adjacent arterioles are contracted to decrease blood flow and prevent formation of edema. Because the venoarteriolar reflex is activated by gravity, we tested the hypothesis that long-term weightlessness would attenuate it. The reduction in subcutaneous blood flow was measured by the 133Xe washout technique just proximal to the ankle joint in dependent lower legs of eight supine astronauts, where the knee joint was passively bent by 90°. The measurements were conducted before spaceflight and 3–6 h on landing following 4–6.5 mo in space. Activation of the venoarteriolar reflex reduced subcutaneous blood flow by 37 ± 9% ( P = 0.016) before flight and by 64 ± 8% ( P < 0.001) following landing with no statistical significant difference between the two reductions ( P = 0.062). Therefore, our results show that the venoarteriolar reflex is not attenuated by weightlessness and therefore does not need the everyday stimulus of gravity to maintain efficiency.

Tissue-specific extravasation of albumin-bound Evans blue in hypothermic and rewarmed rats

The effects of hypothermia and rewarming on endothelial integrity were examined in intestines, kidney, heart, gastrocnemius muscle, liver, spleen, and brain by measuring albumin-bound Evans blue loss from the vasculature. Ten groups of twelve rats, normothermic with no pentobarbital, normothermic sampled at 2, 3, or 4 h after pentobarbital, hypothermic to 20, 25, or 30°C, and rewarmed from 20, 25, or 30°C, were cooled in copper coils through which water circulated. Hypothermic rats were cooled to the desired core temperature and maintained there for 1 h; rewarmed rats were cooled to the same core temperatures, maintained there for 1 h, and then rewarmed. Following Evans blue administration, animals were euthanized with methoxyflurane, tissues removed, and Evans blue extracted. Because hypothermia and rewarming significantly decrease blood flow, organ-specific flow rates for hypothermic and rewarmed tissues were used to predict extravasation. Hypothermia decreased extravasation in tissues with continuous endothelium (brain, muscle) and increased it in tissues with discontinuous endothelium (liver, lung, spleen). All tissues exhibited significant (p < 0.05) differences from normothermic controls. These differences are attributed to a combination of anesthesia, flow, and (or) change in endothelial permeability, suggesting that appropriate choice of organ and temperature would facilitate testing pharmacological means of promoting return to normal perfusion.Key words: hypothermia, rewarming, vascular permeability, Evans blue, endothelium, anesthesia, thermoregulation.

Vasopressin constricts outer medullary descending vasa recta isolated from rat kidneys

Arginine vasopressin (AVP) can selectively decrease blood flow in the renal medulla, but the sites of vasoconstriction are uncertain. We have examined the effects of vasopressin-receptor agonists and antagonists on the diameters of outer medullary descending vasa recta (OMDVR), isolated and perfused in vitro. AVP can constrict OMDVR, apparently via V1a-receptors. Ablumenal AVP (10(-10)-10(-6)M) or the selective V1a-receptor agonist [Phe2, Ile3, Orn8]-vasopressin (PO-VT, 10(-8) M) constricted OMDVR focally and (at higher AVP concentrations) transiently. The V1b agonist ideamino-Cys1,D-3-(pyridyl)Ala2,Arg8)vasopressin (DP-VP; 10(-8) M) and the V2 agonist [deamino-Cys1, D-Arg8]vasopressin (DDAVP; 10(-8) M) did not constrict OMDVR. The V1a antagonist [d(CH2)5(1), O-Me-Tyr2,Arg8]vasopressin (CTM-VP, 10(-10) 10(-8) M) inhibited vasoconstriction by AVP 10(-9 M), whereas the V2 antagonist [d(CH2)5(1), D-Ile2,Ile4 Arg8]vasopressin (II-VP) at low concentration (10(-10) M) did not. V2 stimulation seems to inhibit V1a constriction of OMDVR. DDAVP prevented constriction by PO-VT (10(-8) M) applied at the same time and dilated OMDVR preconstricted with PO-VT.

Inhibition of fluorouracil-induced stomatitis by oral cryotherapy.

Mucositis is a significant dose-limiting toxicity associated with fluorouracil (5FU), particularly when it is combined with leucovorin. We hypothesized that oral cryotherapy would cause local vasoconstriction and would temporarily decrease blood flow to the oral mucous membranes. If cryotherapy were used during the time of peak serum 5FU levels, then the oral mucous membranes would have less exposure to 5FU and thus develop less mucositis. To test this hypothesis, 95 patients scheduled to receive their first cycle of 5FU plus leucovorin were randomized to have oral cryotherapy at the time of chemotherapy administration or to serve as a control group. Subsequent mucositis was significantly reduced in the group assigned to receive cryotherapy as judged by the attending physicians (P = .0002) and by the patients themselves (P = .0001). We now routinely recommend this cryotherapy procedure for our patients receiving daily bolus 5FU plus leucovorin.