Other Regional and Local Analgesia
Pamela E. Macintyre, Stephan A. Schug in Acute Pain Management, 2021
The use of regional and local anesthetic techniques other than neuraxial blockade to provide postoperative and postinjury analgesia continues to gain in popularity. The technique provides extended regional analgesia with minimal systemic adverse effects, facilitating recovery and ongoing physiotherapy and rehabilitation. However, there are no clinical benefits from adding either clonidine or epinephrine to solutions used for CPNB; epinephrine may even carry an increased risk of reduced blood flow to nerves due to prolonged vasoconstriction. Newer pumps have the capability to deliver bolus doses on patient request or automatically at set dosing intervals. Standard orders for CPNB should cover monitoring and documentation, medication orders and responses required for inadequate analgesia or management of adverse effects. However, patient-controlled CPNB, using patient-controlled bolus doses with a continuous background infusion, consistently reduce total consumption of local anesthetic and often supplemental systemic analgesic requirements compared to continuous infusions.
Basic Thermal Physiology: What Processes Lead to the Temperature Distribution on the Skin Surface
Kurt Ammer, Francis Ring in The Thermal Human Body, 2019
The “Glossary of Terms for Thermal Physiology” provides useful definitions of the terms control and regulation. In the 1990s, evidence was raised that sympathetic nerve fibres control both vascular skin responses to thermal stimuli, vasodilation in case of heat load and vasoconstriction in case of heat loss. One is to modify the heat transfer to the environment by changing the thermal resistance and/or heat dissipation, the other is increasing or decreasing heat production. Research in the 1970s reported that some neurons of the mesencephalic reticular formation exhibit a high thermal sensitivity. 8% of these neurons can be considered as cold primary detectors and 79% as warm primary detectors, whereas the remaining 13% are interneurons. Specified threshold temperatures for certain thermo-effectors may change during the processes of fever, acclimatization and adaptation. Threshold temperature and thermo-effector gain are the dominant parameters describing the thermo-effector output as a function of body temperature, thus, they constitute essential characteristics of the thermal controller.
High altitude pulmonary edema
Andrew M. Luks, Philip N. Ainslie, Justin S. Lawley, Robert C. Roach, Tatum S. Simonson in Ward, Milledge and West's High Altitude Medicine and Physiology, 2021
This chapter explores the last of the main forms of acute altitude illness, high altitude pulmonary edema (HAPE). It addresses the most current understanding of HAPE pathophysiology, with a focus on the role of exaggerated hypoxic pulmonary vasoconstriction, as well as the key features of individuals prone to recurrence with repeated rapid ascents to high elevation. This discussion is followed by a thorough review of the clinical aspects, including symptoms and signs, diagnostic approach, imaging findings, and best practices for prevention and treatment. The incidence of HAPE is far lower among high altitude travelers than that reported for acute mountain sickness. The presence of markedly increased pulmonary artery pressure was initially recognized in many of the early studies of HAPE in the 1960s during which patients underwent right-heart catheterization and direct measurement of pulmonary artery pressure prior to initiation of treatment.
Comparative efficacy of vasoconstrictor therapies for type 1 hepatorenal syndrome: a network meta-analysis
Published in Expert Review of Gastroenterology & Hepatology, 2017
Ji-Na Zheng, Yi-Jing Han, Tian-Tian Zou, Yu-Jie Zhou, Dan-Qin Sun, Jian-Hong Zhong, Martin Braddock, Ming-Hua Zheng
Introduction: The outcome of a comparative efficacy and safety of vasoconstrictor therapies for treatment of patients with type 1 hepatorenal syndrome (HRS-1) remain inconclusive. Areas covered: We searched literature databases for randomized controlled trials (RCTs) until 31 January 2016, and included ten eligible RCTs. In conclusion, terlipressin was the most efficacious vasoconstrictor drug for HRS-1, but had a higher probability of causing AEs. Norepinephrine was an attractive alternative to terlipressin and associated with less AEs. Expert commentary: To date, most previous traditional meta-analyses included trials with a limited population and compared terlipressin alone or with albumin against no intervention or albumin. Since different HRS types have different diagnoses and show different responses to vasoconstrictors, it may be questionable to combine data from patients with type 1 and type 2 HRS, which has been reported for most previous meta-analyses. Thus, performing a high-quality network meta-analysis of the existing literature is a valuable way to interrogate published data and to draw conclusions which may inform on the best interventional strategy.
Micronized progesterone reduces vasoconstriction in the placenta
Published in The Journal of Maternal-Fetal & Neonatal Medicine, 2015
Nathaniel R. Miller, Brad M. Dolinsky, Peter G. Napolitano
Objective: To investigate if micronized progesterone (P4) has the ability to attenuate thromboxane mimetic U46619-mediated fetoplacental artery vasoconstriction. Methods: Paired cotyledons obtained from the same placenta of five-term subjects were analyzed. The fetal artery and maternal intervillous space of one cotyledon was infused with P4 while another cotyledon was infused with control perfusate. After 30 min, a bolus dose of U44619 was administered to both cotyledons. Results: The change in the measured fetoplacental vascular pressure caused by bolus administration of U46619 was less in the cotyledons infused with P4 (p = 0.009). Conclusion: Continuous treatment with P4 significantly attenuates the U46619-mediated fetoplacental vasoconstriction.
Attenuated cold defense responses in orexin neuron-ablated rats
Published in Temperature, 2016
Mazher Mohammed, Masashi Yanagisawa, William Blessing, Youichirou Ootsuka
Recent reports of the use of transgenic mice targeting orexin neurons show that the ablation of orexin neurons in the hypothalamus causes hypothermia during cold exposure. This suggests the importance of orexin neurons for cold-induced autonomic and physiological defense responses, including brown adipose tissue (BAT) thermogenesis and vasoconstriction in thermoregulatory cutaneous vascular bed. The present study investigated whether the ablation of orexin neurons attenuated cold-elicited BAT thermogenesis and cutaneous vasoconstriction. The study took advantage of our established conscious rat experimental model of direct measurement of BAT and body temperature and tail cutaneous blood flow. The study used transgenic orexin neurons-ablated (ORX-AB) rats and wild type (WT) rats. BAT temperature and tail artery blood flow with pre-implanted probes were measured, as well as behavioral locomotor activity under conscious free-moving condition. Gradually, the ambient temperature was decreased to below 5°C. ORX-AB rats showed an attenuated cold-induced BAT thermogenesis and behavioral activity, and delayed tail vasoconstriction. An ambient temperature that initiated BAT thermogenesis and established full cutaneous vasoconstriction was 14.1 ± 1.9 °C, which was significantly lower than 20.5 ± 1.9 °C, the corresponding value in WT rats (n = 10, P < 0.01). The results from this study suggest that the integrity of orexin-synthesising neurons in thermoregulatory networks is important for full expression of the cold defense responses.