Acidosis and its associated pathologies predispose patients to develop cardiac arrhythmias and even cardiac arrest. These arrhythmias are assumed to be the result of membrane depolarization, however, the exact mechanism of depolarization during acidosis is not well defined. In our study, the model of quantum tunneling of protons is used to explain the membrane depolarization that occurs during acidosis. It is found that protons can tunnel through closed activation and inactivation gates of voltage-gated sodium channels Nav1.5 that are present in the membrane of cardiac cells. The quantum tunneling of protons results in quantum conductance, which is evaluated to assess its effect on membrane potential. The quantum conductance of extracellular protons is higher than that of intracellular protons. This predicts an inward quantum current of protons through the closed sodium channels. Additionally, the values of quantum conductance are influential and can depolarize the membrane potential according to the quantum version of the GHK equation. The quantum mechanism of depolarization is distinct from other mechanisms because the quantum model suggests that protons can directly depolarize the membrane potential, and not only through indirect effects as proposed by other mechanisms in the literature. Understanding the pathophysiology of arrhythmias mediated by depolarization during acidosis is crucial to treat and control them and to improve the overall clinical outcomes of patients.

Background: Infrared thermal imaging is a non-invasive technique capable of detecting changes in temperature that could ultimately signify changes in blood supply. Flir One is a smartphone-based thermal camera, working by a downloadable application, capable of detecting the limb temperature through a non-contact method using infrared thermography technology. Using the Flir One camera, we will assess the lower limb reperfusion profile following the tourniquet release post total knee arthroplasty (TKA). Methods: A prospective study included 46 patients who underwent primary TKA. We used the (Flir One Gen 3) thermographic camera to capture images at ankle joint preoperatively, and at 1, 10, and 20 minutes post tourniquet release on operation side. The contralateral ankle stands as control. Results: The mean preoperative temperature (in Celsius) of ankle control side and operated side were 33.03 (SD=1.65) and 33.26 (SD=1.42), respectively. The mean ankle temperature on operation side was 19.73 (SD=2.85), 30.49 (SD=2), and 32.43 (SD=1.31) at 1, 10, and 20 minutes post tourniquet release, respectively, while the control side showed a mean temperature of 32.85 (SD=1.42), 32.84 (SD=0.91), and 33.15 (SD=0.95) at the same time intervals. There was a significant statistical difference between both ankle temperatures at 1 and 10 minutes (P=0.00 for each time). At 20 minutes, 37 ankles (80.4%) at operation side reached a temperature level similar but below the level of control side; however, the difference was not significant (P=0.692). Conclusion: Infrared thermography using the smartphone-connected camera is a simple, non-invasive, feasible, and reliable technology. It provides an objective measure to assess the perfusion status of the limbs. In TKA, the distal limb will reach full reperfusion status after approximately 20 minutes of tourniquet release.

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