Anesthesia and analgesia
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Anesthesia and analgesia · Jul 2004
Utility of intraoperative transesophageal echocardiography for diagnosis of pulmonary embolism.
Pulmonary embolism (PE) is associated with significant perioperative morbidity and mortality. Transesophageal echocardiography (TEE) may permit direct visualization of PE or secondary signs of pulmonary artery (PA) obstruction. However, its utility in diagnosing PE in the intraoperative setting has yet to be defined. ⋯ TEE evidence of right ventricular dysfunction was observed in 96%, tricuspid regurgitation in 50%, and leftward interatrial septal bowing in 98% of examinations. Therefore, the use of intraoperative TEE to diagnose acute PE via direct visualization is limited. Indirect TEE evidence of PA obstruction may be helpful in supporting a diagnosis of PE.
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Anesthesia and analgesia · Jul 2004
Intrathecal catheterization and solvents interfere with cortical somatosensory evoked potentials used in assessing nociception in awake rats.
We assessed the objective measurement of central sensitization processes in the awake rat after subcutaneous formalin with cortical somatosensory evoked potentials (CSEPs). Cranial extradural electrodes and intrathecal catheters were implanted in adult male Wistar rats. After 7 days of recovery, CSEPs were induced by electrical stimuli at the tail and recorded before/after the injection of 50 microL of 2% formalin into the hindpaw of rats for 1 h. ⋯ We found that the amplitudes of both signals increased (154.3% +/- 10.9% and 168.7% +/- 9.8%, respectively) from 10 min after formalin injection to the end of the 60-min test period. Pretreatment with intrathecal ketorolac dose-dependently prevented the increases induced by formalin in both measured variables. Moreover, the increases in P1-N1 and N2 were markedly attenuated either by intrathecal polyethylene-10 tubing or by the solvents used for injection, thus indicating the need for distinguishing an impaired nociceptive signal from antinociception when the effects of drugs are evaluated.
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Anesthesia and analgesia · Jul 2004
The development and application of an instrument for assessing resident competence during preanesthesia consultation.
In this study, we aimed to construct, validate, and apply an instrument for assessing resident performance at outpatient preanesthesia consultation (PAC). A focus group and a Delphi panel of experts defined component items of a typical outpatient PAC, which could be used as indicators of competence. Items were incorporated in a checklist, which was further validated in a sample of consultations performed by board-certified anesthesiologists. ⋯ Statistically significant differing levels of performance could be consistently detected. Applying exponentially weighted moving average charts to the sequential analysis of the developed checklist scores can reliably assess resident performance at the devised criteria. The Preanesthesia Consultation Scoring Checklist is a potentially useful instrument for both formative and summative assessment of residents during their training in processes involved in outpatient preanesthesia evaluation.
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Anesthesia and analgesia · Jul 2004
Supplemental oxygen and carbon dioxide each increase subcutaneous and intestinal intramural oxygenation.
Oxidative killing by neutrophils, a primary defense against surgical pathogens, is directly related to tissue oxygenation. We tested the hypothesis that supplemental inspired oxygen or mild hypercapnia (end-tidal PCO2 of 50 mm Hg) improves intestinal oxygenation. Pigs (25 +/- 2.5 kg) were used in 2 studies in random order: 1) Oxygen Study: 30% versus 100% inspired oxygen concentration at an end-tidal PCO2 of 40 mm Hg, and 2) Carbon Dioxide Study: end-tidal PCO2 of 30 mm Hg versus 50 mm Hg with 30% oxygen. ⋯ Oxygen 100% administration doubled subcutaneous oxygen partial pressure (PO2) (57 +/- 10 to 107 +/- 48 mm Hg, P = 0.006) and large intestine intramural PO2 (53 +/- 14 to 118 +/- 72 mm Hg, P = 0.014); intramural PO2 increased 40% in the small intestine (37 +/- 10 to 52 +/- 25 mm Hg, P = 0.004). An end-tidal PCO2 of 50 mm Hg increased large intestinal PO2 approximately 16% (49 +/- 10 to 57 +/- 12 mm Hg, P = 0.039), whereas intramural PO2 increased by 45% in the small intestine (31 +/- 12 to 44 +/- 16 mm Hg, P = 0.002). Supplemental oxygen and mild hypercapnia each increased subcutaneous and intramural tissue PO2, with supplemental oxygen being most effective.
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Anesthesia and analgesia · Jul 2004
Comparative StudyGamma-aminobutyric acidA receptors do not mediate the immobility produced by isoflurane.
Many inhaled anesthetics enhance the effect of the inhibitory neurotransmitter gamma aminobutyric acid (GABA), supporting the view that the GABAA receptor could mediate the capacity of inhaled anesthetics to produce immobility in the face of noxious stimulation (i.e., MAC, the minimum alveolar concentration required to suppress movement in response to a noxious stimulus in 50% of subjects). However, only limited in vivo data support the relevance of the GABAA receptor to MAC. In the present study we used two findings to test for the relevance of this receptor to immobilization for isoflurane: 1) differences among anesthetics in their capacity to enhance the response of receptor expression systems to GABA: isoflurane (considerable enhancement), xenon (minimal enhancement), and cyclopropane (minimal enhancement); and 2) studies showing that the spinal cord mediates MAC for isoflurane. ⋯ This indicates that GABA release in the spinal cord influences anesthetic requirement. However, the increase did not consistently differ among anesthetics and did not correlate with in vitro enhancement of GABAA receptors by these anesthetics. This supports the view that GABAA receptors do not mediate immobilization for isoflurane.