Der Anaesthesist
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During the last 30 years intraoperative electrophysiological monitoring (IOEM) has gained increasing importance in monitoring the function of neuronal structures and the intraoperative detection of impending new neurological deficits. The use of IOEM could reduce the incidence of postoperative neurological deficits after various surgical procedures. Motor evoked potentials (MEP) seem to be superior to other methods for many indications regarding monitoring of the central nervous system. ⋯ When intraoperative MEP or electromyography guidance is planned, muscle relaxation must be either completely omitted or maintained in a titrated dose range in a steady state. The IOEM can be performed by surgeons, neurologists and neurophysiologists or increasingly more by anesthesiologists. However, to guarantee a safe application and interpretation, sufficient knowledge of the effects of the surgical procedure and pharmacological and physiological influences on the neurophysiological findings are indispensable.
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Studies conducted shortly after the implementation of pulse oximetry (PO) into clinical practice 20-25 years ago revealed that many patients breathing room air during transfer from the operating room (OR) to the post-anesthesia care unit (PACU) directly after general anesthesia (GA) had a peripheral oxygen saturation (S(p)O(2)) below 90%. Moreover, it was shown that the detection of hypoxemia by clinical criteria is extremely unreliable. Meanwhile, the use of PO has become part of the obligatory standard monitoring during GA in Germany and many other countries. Likewise, the use of PO is standard care in the PACU although there are no official recommendations. However, for the time period in between, i.e. immediately after GA during transportation of patients from the OR to the PACU, monitoring of the S(p)O(2) in patients breathing room air is neither obligatory in Germany nor are there any official recommendations or guidelines in this respect. Given the introduction of shorter acting anesthetic agents within the last 25 years, the main goal of this study was to explore whether the incidence of hypoxemia in the immediate period after GA is still so high. Additional aims of this study were to examine whether the detection of hypoxemia based on clinical criteria can be confirmed to be very unreliable, what the risk factors for hypoxemia following GA are and how common it is in Germany to transport patients from the OR to the PACU without PO and supplemental oxygen. ⋯ The use of opioids and relaxants with short duration of action may have favorable effects on preventing hypoxemia and decreases of S(p)O(2). These measures will, however, not be sufficient to solve this problem because the highest risk factors for hypoxemia are patient-related. Despite knowing risk factors for oxygen desaturation, it is currently not possible to reliably predict which patients will become hypoxemic or have a decrease of S(p)O(2). Therefore, transportation of patients breathing room air from the OR to the PACU directly after GA without use of PO or supplemental oxygen seems to be questionable in terms of patient safety.
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Randomized Controlled Trial Comparative Study
[Comparison of ready-to-use devices for emergency cricothyrotomy : randomized and controlled feasibility study on a mannequin].
According to various algorithms of airway management, emergency cricothyrotomy (coniotomy) represents the ultimate step for managing the difficult airway. As most physicians have limited experience with this technique several ready-to-use devices have emerged on the market with the aim of simplifying the procedure. However, they differ in details, such as configuration or the order of particular steps. Therefore, the intention of this randomized and controlled feasibility study was to test various sets and compare them to the classical surgical approach. ⋯ This study allowed the comparison of surgical coniotomy to several ready-to-use devices in a standardized setting utilizing a reusable plastic mannequin. The interpretation for real emergency conditions is limited as individual anatomy, traumatic alterations of the neck or complications, such as bleeding or damage of important structures were not part of the study objectives. However, all participating emergency physicians successfully used the coniotomy sets provided at the first attempt. No device required significantly more time than the surgical approach. The procedures using cuffed devices lasted longer in comparison to procedures using uncuffed ones; however, this difference would only play a minor role in reality as effective ventilation with minute volumes greater than 7 l/min will only be achieved by a cuffed cannula with a minimum internal diameter of 4 mm. Devices with no cuff or with tube diameters smaller than 4 mm will only allow oxygenation of the patient, which in turn requires an inspiratory oxygen concentration of 100% and a relatively high ventilation frequency.