Anesthesia, essays and researches
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Awake fiberoptic intubation (AFOI) is a recommended technique for anticipated difficult airway. An ideal regime should provide patient comfort, cooperation, amnesia, hemodynamic stability, and blunt airway reflexes and maintain a patent airway with spontaneous ventilation. The aim of our study was to compare intubation conditions between dexmedetomidine and fentanyl-midazolam combination during AFOI. ⋯ Dexmedetomidine is more effective than midazolam-fentanyl during AFOI, as it provides better intubation condition, hemodynamic stability, and preservation of airway and spontaneous ventilation.
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Brachial plexus block is effective with good postoperative analgesia in upper limb surgery has gained importance as it safe, low cost, and maintains stable hemodynamics intraoperatively. To decrease the onset time and prolong the duration of nerve block bicarbonate, opioids (morphine, fentanyl, etc.), sympathomimetic agents (epinephrine, phenylephrine, etc.), α-2 agonists (clonidine and dexmedetomidine), calcium channel blocker (verapamil), magnesium sulfate, etc., were studied with local anesthetics and their isomers. For their sedative, analgesic, perioperative sympatholytic, and cardiovascular stabilizing effects with reduced anesthetic requirements, α-2 adrenergic receptor agonists, such as more potent and highly selective dexmedetomidine, have been the focus of interest for regional anesthesia. Intravenous dexmedetomidine infusion resulted in significant opioid-sparing effects as well as a decrease in inhalational anesthetic requirements. Animal studies proved that dexmedetomidine enhances sensory and motor blockade along with increased duration of analgesia. In humans, dexmedetomidine has also shown to prolong the duration of block and postoperative analgesia when added to local anesthetic in various regional blocks. Bupivacaine, the widely used local anesthetic in regional anesthesia, is available in a commercial preparation as a racemic mixture (50:50) of its two enantiomers: levobupivacaine, S (-) isomer and dextrobupivacaine, R (+) isomer. Severe central nervous system and cardiovascular adverse reactions reported in the literature after inadvertent intravascular injection or intravenous regional anesthesia have been linked to the R (+) isomer of bupivacaine. The levorotatory isomers were shown to have a safer pharmacological profile with less cardiac and neurotoxic adverse effects. The decreased toxicity of levobupivacaine is attributed to its faster protein binding rate. The pure S (-) enantiomers of bupivacaine, i.e., ropivacaine and levobupivacaine were thus introduced into the clinical anesthesia practice. Such an increased usage mandates the documentation of evidence-based literature with regard to risk and safety concerns as well as clinical issues related to levobupivacaine. This study is designed to assess the efficacy of adding dexmedetomidine to levobupivacaine during placement of supraclavicular brachial plexus blockade. ⋯ Addition of 0.75 μg/kg dexmedetomidine to 0.5% levobupivacaine for supraclavicular plexus block shortens sensory and motor block onset time and extends sensory block, motor block, and analgesia duration.
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Positive end-expiratory pressure (PEEP) at the time of induction increases oxygenation by preventing lung atelectasis. However, PEEP may not prove beneficial in all cases. Factors affecting the action of PEEP have not been elucidated well and remain controversial. Pulmonary vasculature has direct bearing on the action of PEEP as has been proven in the previous studies. Thus, this prospective study was planned to evaluate the action of PEEP on the basis of pulmonary artery systolic pressure (PASP) which is noninvasive and easily measured by transthoracic echocardiography. ⋯ Morbidly obese patients who have PASP >30 mm Hg benefit most from the PEEP. Thus, PASP which is an easily measurable noninvasive parameter can be used as a criterion for selecting patients who benefit from PEEP application.
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The combined spinal epidural (CSE) technique involves intentional subarachnoid blockade and epidural catheter placement during the same procedure to combine their individual best features, to reduce the total drug dosage and avoid their respective disadvantages. The addition of opioids to local anesthetics (bupivacaine) for CSE anesthesia (CSEA) is increasingly common to enhance the block. Neuraxial fentanyl is more potent and has shorter duration of action than morphine which provides prolonged anesthesia and analgesia, however at the cost of increased incidence of adverse effects like delayed respiratory depression. ⋯ Group A had significantly prolonged two segment regression time, T11 regression time, lower mean VAS score, prolonged effective analgesia, and required lesser number of epidural boluses in 24 h as compared to Group B (P < 0.001). There were no significant differences between the groups considering onset of sensory block, duration of motor block, median maximum sensory block level achieved after spinal component (T6), median highest sensory block level achieved after epidural anesthetic bolus (T7-4seg enhancement after regression to T11), cardiorespiratory parameters and adverse effects. None of the patients had respiratory depression nor was there any failure of spinal/epidural component of CSEA. Thus, addition of morphine to bupivacaine in CSEA produced prolonged effective anesthesia and postoperative analgesia compared to addition of fentanyl to bupivacaine without producing undue adverse effects.
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Transsphenoidal approach to pituitary tumors is a commonly performed procedure with the advantage of a rapid midline access to the sella with minimal complications. It may be associated with wide fluctuations in hemodynamic parameters due to intense noxious stimulus at various stages of the surgery. As duration of the surgery is short and the patients have nasal packs, it is prudent to use an anesthestic technique with an early predictable recovery. ⋯ A continuous intravenous infusion of dexmedetomidine as compared to oral clonidine improved hemodynamic stability in patients undergoing transnasal transsphenoidal resection of pituitary tumors.