Hydrogen sulfide (H2S), which has a characteristic rotten egg smell, is a colorless, flammable, water-soluble gas that is primarily considered a toxic agent due to its ability to inhibit mitochondrial respiration through blockade of cytochrome c oxidase. Recent research has demonstrated that H2S in low quantities may have the potential to limit cell death (Lefer, 2007). Inhibition of respiration is potentially toxic; however, if depression of respiration occurs in a controlled manner, it may allow non-hibernating species exposed to inhaled H2S to enter a state akin to suspended animation (i.e., a slowing of cellular activity to a point where metabolic processes are inhibited but not terminal) and thereby increase tolerance to stress. H2S also may cause activation of ATP-dependent K+ channels, cause vasodilation properties, and serve as a free radical scavenger. H2S has been shown to protect against whole-body hypoxia, lethal hemorrhage, and ischemia-reperfusion injury in various organs including the kidney, lung, liver, and heart. Currently, effort is underway for development of gas-releasing molecules that could deliver H2S and other therapeutic gases to diseased tissue (Bannenberg and Vieira, 2009). Though H2S has clinical potential, further verification in preclinical models is necessary as is more information regarding the route of delivery, timing, formulation, and concentration of H2S.
Anesthesia for Pregnant woman with Pulmonary Hypertension is a real challenge for anesthesiologist. It is very crucial to remember the pathophysiology of pulmonary hypertension in pregnant women and to avoid some practices that will worsen the cardiac status. 1-Avoid single shot spinal anesthesia. Some authorities consider pulmonary hypertension as absolute contraindication for single shot spinal anesthesia specially in patients with NYHA III ,IV. Spinal anesthesia causes major hemodynamic instability(decrease SVR, decrease VR, decrease in CO) The preferred neuroaxial techniques are (epidural anesthesia and CSE with minimal spinal dose) 2-Avoid PAC. Pulmonary Artery catheters insertion may lead to pulmonary artery rupture or thrombosis. TEE is better cardiac monitor/Arteial line is mandatory. 3-Avoid Nitrous oxide in gas mixture.N2O increase the PVR 4-If MV to be started, avoid High TV and PEEP 5-Avoid Oxytocin Boluses, or rapid administration of Pitocin. Oxytocin causes ...
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