Anesthesia and analgesia
-
Anesthesia and analgesia · Jul 2009
Comparative StudyCan mixed venous hemoglobin oxygen saturation be estimated using a NICO monitor?
We hypothesized that mixed venous hemoglobin oxygen saturation (SvO2) can be estimated by calculation from CO2 production, cardiac output, and arterial oxygen saturation measured using a noninvasive cardiac output (NICO) monitor (Novametrix-Respironics, Wallingford, CT). ⋯ SvO2 derived from the values measured by the NICO monitor cannot be used interchangeably with the values measured spectrophotometrically using the pulmonary artery catheter. More refinement is required to obtain more reliable estimate of SvO2 less invasively. However, large changes of SvO2 may be detected with this method and can be used as a precautionary sign when the balance between oxygen supply and demand is compromised without inserting a central venous catheter.
-
Anesthesia and analgesia · Jul 2009
Randomized Controlled Trial Comparative StudyA prospective, randomized, controlled trial comparing ultrasound versus nerve stimulator guidance for interscalene block for ambulatory shoulder surgery for postoperative neurological symptoms.
Visualization with ultrasound during regional anesthesia may reduce the risk of intraneural injection and subsequent neurological symptoms but has not been formally assessed. Thus, we performed this randomized clinical trial comparing ultrasound versus nerve stimulator-guided interscalene blocks for shoulder arthroscopy to determine whether ultrasound could reduce the incidence of postoperative neurological symptoms. ⋯ Ultrasound reduced the number of needle passes needed to perform interscalene block and enhanced motor block at the 5 min assessment; however, we did not observe significant differences in block failures, patient satisfaction or incidence, and severity of postoperative neurological symptoms.
-
Anesthesia and analgesia · Jul 2009
Comparative StudyThe effects of arterial carbon dioxide partial pressure and sevoflurane on capillary venous cerebral blood flow and oxygen saturation during craniotomy.
Intraoperative routine monitoring of cerebral blood flow and oxygenation remains a technological challenge. Using the physiological principle of carbon dioxide reactivity of cerebral vasculature, we investigated a recently developed neuromonitoring device (oxygen-to-see, O2C device) for simultaneous measurements of regional cerebral blood flow (rvCBF), blood flow velocity (rvVelo), oxygen saturation (srvO2), and hemoglobin amount (rvHb) at the capillary venous level in patients subjected to craniotomy. ⋯ Increases in rvCBF and rvVelo by PaCO2 suggest preserved hypercapnic vasodilation under anesthesia with sevoflurane 1.4% and 2.0% end-tidal concentration. A consecutive increase in srvO2 implies that cerebral arteriovenous difference in oxygen was decreased by elevated PaCO2. Unchanged levels of rvHb signify that there was no blood loss during measurements. Data suggest that the device allows detection of local changes in blood flow and oxygen saturation in response to different PaCO2 levels in predominant venous cerebral microvessels.
-
Anesthesia and analgesia · Jul 2009
Randomized Controlled Trial Comparative StudyThe interaction between epidural 2-chloroprocaine and morphine: a randomized controlled trial of the effect of drug administration timing on the efficacy of morphine analgesia.
The efficacy and duration of epidural morphine analgesia is diminished when administered after 2-chloroprocaine compared with lidocaine. The mechanism of the interaction between 2-chloroprocaine and morphine is unknown. Possible explanations include differences in the latency and duration of action of the two drugs or opioid receptor antagonism. We hypothesized that administration of epidural morphine 30 min before the initiation of 2-chloroprocaine anesthesia would result in postoperative analgesia of similar duration and quality to that achieved by epidural morphine after the initiation of lidocaine anesthesia in patients undergoing postpartum tubal ligation. ⋯ This study demonstrates that administration of epidural morphine 30 min before epidural anesthesia with 2-chloroprocaine provides a similar duration of analgesia as epidural morphine after epidural lidocaine anesthesia. This suggests that the observed interaction between epidural morphine and 2-chloroprocaine is a result of differences in latency and duration of action of the two drugs, or that the administration of morphine before 2-chloroprocaine effectively blocks a receptor site antagonism.
-
Anesthesia and analgesia · Jul 2009
Comparative StudyThe effect of duration of surgery on fluid balance during abdominal surgery: a mathematical model.
There is controversy regarding which fluid management regimen provides the best postoperative outcome. Interstitial fluid accumulation may adversely affect postoperative outcome, but the effect of surgical duration on fluid balance is unknown. In this study, we used a mathematical model to describe fluid distribution. ⋯ Based on our model, it should be possible to increase the fluid infusion rate without significant interstitial edema for abdominal surgery of <3 h duration. However, our model predicts that restrictive fluid management should be used in abdominal surgery of >6 h duration to avoid excessive interstitial edema.