Anesthesia and analgesia
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Anesthesia and analgesia · Nov 2006
Comparative StudyThe effect of tracheal gas insufflation on gas exchange efficiency.
Transtracheal gas insufflation (TGI) improves gas exchange efficiency, but is associated with hyperinflation, and usually requires ventilator adjustment to compensate for the increased gas flow. Although bidirectional TGI (Bi-TGI) minimizes hyperinflation, it does not preclude the need to reduce tidal volumes to prevent hyperinflation. A flow-compensation system was developed by Respironics (Murrysville, PA) to match TGI flows; however, neither that nor the efficacy of Bi-TGI have been tested in vivo. ⋯ Bi- and Uni-TGI could be delivered at constant minute ventilation without adjusting ventilatory setting when the flow compensation circuit was present. Uni-TGI produced more hyperinflation than did Bi-TGI with all sizes of endotracheal tube, and hyperinflation was universally present as tube size decreased to 7.5F. We conclude that this new flow compensation system allows for the delivery of TGI without the need for adjustments to the ventilator settings, and that Bi-TGI produces less hyperinflation than does Uni-TGI, even with small diameter endotracheal tubes.
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Anesthesia and analgesia · Nov 2006
Comparative StudyLumbosacral cerebrospinal fluid volume in humans using three-dimensional magnetic resonance imaging.
The clinical response to spinal anesthesia is influenced by lumbosacral cerebrospinal fluid (CSF) volume, which is highly variable among patients. ⋯ Application of this technique to clinical investigations may further enhance our understanding of spinal anesthesia.
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Anesthesia and analgesia · Nov 2006
Comparative StudyVariations in arterial blood pressure and photoplethysmography during mechanical ventilation.
We analyzed ventilation-induced changes in arterial blood pressure and photoplethysmography from waveforms obtained by monitoring 57 patients in the operating room and intensive care unit. Analysis of systolic and pulse pressure variations during positive pressure ventilation, DeltaUp, DeltaDown, and changes in the preejection period on both arterial and photoplethysmographic waveforms were possible in 49 (86%) patients. The pulse pressure variation and preejection period were similar when calculated using both arterial blood pressure and photoplethysmography, whereas the other variables were different. ⋯ In hypotensive patients, photoplethysmographic pulse variation >9% remained the best threshold value (pulse pressure variation >13%: area under ROC curve = 0.90; DeltaDown >5 mm Hg: area under ROC curve = 0.93) for predicting fluid responsiveness. In conclusion, this study showed that pulse variations observed in the arterial pressure waveform and photoplethysmogram are similiar in response to positive pressure ventilation. Furthermore, photoplethysmographic pulse variation > 9% identifies patients with ventilation-induced arterial blood pressure variation that is likely to respond to fluid administration.
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Anesthesia and analgesia · Nov 2006
Comparative StudyTrends in gender distribution among anesthesiology residents: do they matter?
The number of women graduating from United States medical schools progressively increased during the 26 yr period from 1978 to 2004. This change was associated with shifts in the gender distribution of residents training in Accreditation Council for Graduate Medical Education-accredited residency programs. ⋯ The reasons for this distribution are multifactorial. Contributing factors may include limited exposure to women role models (including fewer women with senior academic rank and in leadership positions), gender insensitivity leading to an unprofessional work environment, limited involvement of women anesthesiologists in undergraduate medical education, misperceptions of the physician-patient relationship in anesthesiology, and practice scheduling requirements that are inconsistent and inflexible.
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Anesthesia and analgesia · Nov 2006
Comparative StudyA comparison of epidural pressures and incidence of true subatmospheric epidural pressure between the mid-thoracic and low-thoracic epidural space.
Differences in epidural pressure (EP) may influence the spread of blockade in thoracic epidural anesthesia. We evaluated if EP and the incidence of subatmospheric EP differ between the mid- and low-thoracic epidural space. ⋯ We conclude that EP is lower, and the incidence of subatmospheric EP is higher in the mid-thoracic epidural space when compared with that in the low-thoracic epidural space. However, median EP was positive in both groups. It remains to be investigated whether this pressure gradient is sufficient to influence the spread of thoracic epidural blockade.