Venom induced pressure elevation reversible syndrome: a severe pediatric rattlesnake envenomation, evidence for conservative management, and call for naming the syndromeVenom induced pressure elevation reversible syndrome: a severe pediatric rattlesnake envenomation, evidence for conservative management, and call for naming the syndrome

Posted by
  Venom induced pressure elevation reversible syndrome: a severe pediatric rattlesnake envenomation, evidence for conservative management, and call for naming the syndromeVenom induced pressure elevation reversible syndrome: a severe pediatric rattlesnake envenomation, evidence for conservative management, and call for naming the syndrome Abstract Introduction : Rattlesnake envenomation frequently mimics traumatic compartment syndrome, as both are characterized by severe pain, swelling, and elevated compartment pressures. Unlike traumatic compartment syndrome there have been no documented cases of ischemic limb injury after envenomated patients have received antivenom. Furthermore, there is experimental evidence that fasciotomy worsens myonecrosis. This has led medical toxicologists and surgical guidelines to shift from liberally recommending fasciotomy to near universal recommendation of antivenom alone. Despite this, fasciotomies continue to be recommended and performed on rattle...

Semi-hydraulic actuation in spider legs: The transport of the hemolymph does not hamper muscle driven leg joint flexion

Posted by

 


Semi-hydraulic actuation in spider legs: The transport of the hemolymph does not hamper muscle driven leg joint flexion

Abstract

Hemolymph channels (lacunae) in the legs of spiders are part of their open circulatory system. They are defined as hemolymph-filled spaces between tissues within the exoskeletal tubes of the legs which are otherwise largely filled with muscles. In two of the major leg joints, the leg segments are connected via hinge joints with axes that are located at their dorsal rims.
The lacunae are used to channel hemolymph, which acts as a hydraulic fluid, to the extensor-less joints during the extension of the legs. However, due to competing optimization criteria of muscle-driven flexion and drainage of the hemolymph, fluid drag in the lacunae may hinder movement and force generation during flexion. Numerical modelling of dynamic flexions of the tibia-metatarsus joint, considering anatomical and physiological properties identified in the hunting spider Cupiennius salei, was used to investigate the trade-off between muscular force and hemolymph-drainage. The results showed that the diameters of the hemolymph channels exhibit a broad optimum for quick flexion. Within a wide range of channel diameters flexion times are hardly affected. Muscle properties, especially the time of muscle activation, strongly dampen the effect of the reduced muscle cross-section available. With small loads of 0.1g, similar to the spiders’ common prey size, the radius of the observed effective lacunae seems to enable the fastest flexions. A change in the aspect ratio of the tibia while maintaining the proportionality of its radius and the radius of the effective hemolymph channels leads to an extension of the flexion time.
Blickhan, R., Siebert, T., & Weihmann, T. (2026). Semi-hydraulic actuation in spider legs: The transport of the hemolymph does not hamper muscle driven leg joint flexion. Journal of Theoretical Biology, 620, 112350. https://doi.org/10.1016/j.jtbi.2025.112350