Anesthesia and analgesia
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Anesthesia and analgesia · Sep 1996
Prone positioning improves pulmonary function in obese patients during general anesthesia.
We investigated the effects of prone position on functional residual capacity (FRC), the mechanical properties (compliance and resistance) of the total respiratory system, lung and chest wall, and the gas exchange in 10 anesthetized and paralyzed obese (body mass index more than 30 kg/m2) patients, undergoing elective surgery. We used the esophageal balloon technique together with rapid airway occlusions during constant inspiratory flow to partition the mechanics of the respiratory system into its pulmonary and chest wall components. FRC was measured by the helium dilution technique. ⋯ Resistance of the total respiratory system, lung, and chest wall were not modified on turning the patients prone. The increase in FRC and lung compliance was paralleled by a significant (P < 0.01) improvement of PaO2 from supine to prone position (130 +/- 31 vs 181 +/- 28 mm Hg, P < 0.01), while PaCO2 was unchanged. We conclude that, in anesthetized and paralyzed obese subjects, the prone position improves pulmonary function, increasing FRC, lung compliance, and oxygenation.
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Anesthesia and analgesia · Sep 1996
The dermatomal spread of epidural bupivacaine with and without prior intrathecal sufentanil.
Clinicians often use a technique combining intrathecal sufentanil and epidural bupivacaine to provide labor analgesia. This study determines the effect of 27- or 24-gauge dural puncture and intrathecal sufentanil 10 micrograms on the dermatomal spread of epidural bupivacaine. Healthy laboring women received no dural puncture (n = 77) (no puncture group [NPG]) or dural puncture with a 27-gauge Whitacre needle (n = 33) or a 24-gauge Sprotte needle (n = 37) and intrathecal sufentanil 10 micrograms (dural puncture group [DPG]) before epidural injection of 13 mL bupivacaine 0.25%. ⋯ More patients in the DPG had sensory blockade T-4 or higher (17 of 70 DPG patients vs 8 of 77 NPG patients; P < 0.05). No patient in either group showed clinical evidence of respiratory compromise. In conclusion, epidural bupivacaine anesthetized more dermatomes when administered 104 +/- 42 min after dural puncture and intrathecal sufentanil 10 micrograms than when given without prior dural puncture and intrathecal injection.
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Because of remifentanil's unique pharmacokinetics, its systemic administration may be suitable for clinical settings where a potent, fast-acting, systemic mu-opioid with a rapid recovery is required, e.g., short painful intervention in the emergency room or the intensive care unit, or procedures in the day surgery or endoscopy suite. Total intravenous anesthesia for longer lasting procedures may become more promising because of the predictability of the offset of remifentanil even after long infusions. ⋯ Remifentanil might be the first potent mu-opioid that does not accumulate in this fashion, and therefore it opens promising new clinical perspectives (52). However, as mentioned above, the relative short-lasting analgesic effect after cessation of the remifentanil infusion might require new, sophisticated techniques from the anesthetist to prevent immediate onset of postoperative pain.
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In 236 consecutive lumbar epidural anesthesia patients, epidurography was performed in seven patients who developed unilateral loss of cold sensation to clarify the cause of unilateral block. Epidurography demonstrated the epidural catheter tip location in the anterior epidural space in four patients (57%) and in the transforaminal passage in three patients (43%). In all seven patients, successful bilateral epidural anesthesia was obtained by a second puncture using another catheter. Our results showed that the most frequent cause of unilateral epidural blockade was the misplacement of the catheter into the anterior epidural space.
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Anesthesia and analgesia · Sep 1996
The effect of prior dural puncture on cisternal cerebrospinal fluid morphine concentrations in sheep after administration of lumbar epidural morphine.
Combined spinal epidural anesthesia has become increasingly popular as a method of providing rapid onset of analgesia or surgical block with access for further administration of analgesics or anesthetics. No in vivo studies have evaluated the relationship between dural puncture and drug transfer from the epidural space to the cerebrospinal fluid (CSF). To determine whether morphine administered in the epidural space adjacent to a dural puncture results in increased CSF concentrations at the cisterna magna (CM), 12 adult ewes were studied. ⋯ These data demonstrate that a significant increase in CSF morphine concentration at the brainstem will occur when lumbar epidural morphine is administered adjacent to a dural puncture. Furthermore, the increase in CSF morphine concentration is positively correlated with the size of the needle producing the dural puncture. These findings highlight the potential for delayed respiratory depression when epidural opiate administration follows a dural puncture.