Anesthesia and analgesia
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Anesthesia and analgesia · Sep 2005
Identification of endotracheal tube malpositions using computerized analysis of breath sounds via electronic stethoscopes.
Endotracheal tube (ETT) malpositioning into a mainstem bronchus or the esophagus may result in significant hypoxemia. Current methods to determine correct ETT position include auscultation, radiography, and bronchoscopy, although the current acceptable standard procedure for proper endotracheal (versus esophageal) intubation is detection of end-tidal carbon dioxide (ETco(2)) by capnography, capnometry, or colorimetric ETco(2) devices. Unfortunately, capnography may be unavailable or unreliable in nonhospital/emergency settings or in low cardiac output states, and it does not detect endobronchial intubation. ⋯ Using computerized analysis, breath sounds were digitized and filtered to remove selected frequencies, and acoustic signals and energy ratios were obtained for all 3 positions. Total energy ratios using band-pass filtering of the acoustic signals accurately identified all esophageal and endobronchial intubation (P < 0.001). These preliminary results suggest that this technique, when incorporated into a 3-component, electronic stethoscope-type device, may be an accurate, portable mechanism to reliably detect ETT malposition in adults when ETco(2) may be unavailable or unreliable.
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Anesthesia and analgesia · Sep 2005
Comparative Study Clinical TrialSpinal anesthesia-induced hypotension: a risk comparison between patients with severe preeclampsia and healthy women undergoing preterm cesarean delivery.
We previously showed that, in comparison with term healthy parturients, patients with severe preeclampsia had a less frequent incidence of spinal hypotension, which was less severe and required less ephedrine. In the present study, we hypothesized that these findings were attributable to preeclampsia-associated factors rather than to a smaller uterine mass. The incidence and severity of hypotension were compared between severe preeclamptics (n = 65) and parturients with preterm pregnancies (n = 71), undergoing spinal anesthesia for cesarean delivery (0.5% bupivacaine, sufentanil, morphine). ⋯ The risk of hypotension in the preeclamptic group was almost 2 times less than that in the preterm group (relative risk = 0.603; 95% confidence interval, 0.362-1.003; P = 0.044). The impact of Apgar scores was minor, and umbilical arterial blood pH was not affected. We conclude that preeclampsia-associated factors, rather than a smaller uterine mass, account for the infrequent incidence of spinal hypotension in preeclamptic patients.
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Anesthesia and analgesia · Sep 2005
Isoflurane-induced neuronal degeneration: an evaluation in organotypic hippocampal slice cultures.
Prolonged exposure of postnatal day (PND) 7 rat pups to anesthetics, which act via N-methyl-D-aspartate antagonism and/or gamma-amino butyric acid enhancement, causes neurodegeneration and persistent behavioral deficits. We studied these findings in vitro and determined whether the age of rat pups used for study or duration of anesthetic exposure modulates resultant neurodegeneration. Organotypic hippocampal slices (OHSs) were prepared from rat pups on PNDs 4, 7, and 14 and cultured 7 or 14 days in vitro. ⋯ Hippocampal CA1, CA3, and dentate gyrus neuronal survival was assessed 3 days later. Neuronal cell death was greatest in OHSs prepared from PND 7 rat pups (P < 0.001) and was most evident after 5 h exposure to isoflurane (P < 0.001). By eliminating variables such as hemodynamics, nutrition, oxygenation, and carbon dioxide elimination, this in vitro investigation supports both an age- and duration-dependent relationship between 1.5% isoflurane exposure and perinatal neuronal death.
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Anesthesia and analgesia · Sep 2005
Comparative StudyTemperatures in soda lime during degradation of desflurane, isoflurane, and sevoflurane by desiccated soda lime.
Rarely, fire and patient injury result from the degradation of sevoflurane by desiccated Baralyme. The present investigation sought to determine whether high temperatures also arose with sevoflurane use in the presence of desiccated soda lime. We desiccated soda lime by directing a 10 L/min flow of oxygen through fresh absorbent. ⋯ Concurrent delivery of carbon dioxide and sevoflurane did not increase the peak temperatures reached. The use of 2 canisters increased the duration but not the peak of increased temperature reached with 3.0 MAC sevoflurane. No fires resulted from degradation of any anesthetic.
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Anesthesia and analgesia · Sep 2005
An algorithm for processing vital sign monitoring data to remotely identify operating room occupancy in real-time.
We developed an algorithm for processing networked vital signs (VS) to remotely identify in real-time when a patient enters and leaves a given operating room (OR). The algorithm addresses two types of mismatches between OR occupancy and VS: a patient is in the OR but no VS are available (e.g., patient is being hooked up), and no patient is in the OR but artifactual VS are present (e.g., because of staff handling of sensors). The algorithm was developed with data from 7 consecutive days (122 cases) in a 6 OR trauma center. ⋯ Identified patient in- and out-times were accurate within 4.9 min (CI 4.2-5.7) and 2.8 min (CI 2.3-3.5), respectively, and were not different in accuracy from times reported by staff on OR records. The algorithm's usefulness was demonstrated partly by its continued operational use. We conclude that VS can be processed to accurately report OR occupancy in real-time.