Journal of clinical monitoring and computing
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J Clin Monit Comput · Apr 1998
Comparative carbon dioxide output through injured and noninjured peritoneum during laparoscopic procedures.
Tension pneumoperitoneum may force gas into a small injured vessel if the opening is kept patent by surrounding tissues. However, the amount of carbon dioxide (CO2) that penetrates through injured or noninjured peritoneum has not been systematically determined. In 25 patients undergoing elective laparoscopic ultrasonography and cholecystectomy, CO2 output (VCO2) and O2 uptake (VO2) were measured at baseline and during anesthesia, pneumoperitoneum, laparoscopic surgical procedure (Surgery), and after hemostasis of the surgical field (Postsurgery). ⋯ Minute volume increased from 2.24 +/- 0.20 in anesthesia to 2.89 +/- 0.25, 4.01 +/- 0.32, and 3.46 +/- 0.28 L x min(-1) x m(-2) during pneumoperitoneum, Surgery, and Postsurgery, respectively, to maintain PaCO2. We conclude that the amount of CO2 absorbed following pneumoperitoneum prior to surgery is lower than that during Surgery or Postsurgery. The amount of CO2 absorbed through the surgical field was 2.3 times higher than that through the nonsurgical field while that from the peritoneum after hemostasis of surgical field was 1.6 times higher.
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J Clin Monit Comput · Apr 1998
Estimation of ventricular volume and elastance from the arterial pressure waveform.
We propose that it is possible to estimate cardiovascular parameters from the arterial pressure waveform, including ventricular maximal elastance and end-diastolic volume, if cardiac output is also known. We tested this hypothesis by means of a parameter estimation algorithm applied to simulated arterial pressure signals. The program first estimated three coefficients representing products of passive parameters from the diastolic part of the simulated arterial pressure waveform. ⋯ This program was tested on 200 computer-generated arterial pressure signals, obtained by simulating the model with random but bounded parameters. Correlation between estimated parameters with those actually used in the simulations was excellent. Even though the value of this computer simulation is limited to the simplified model used and requires experimental validation, it demonstrates that the technique is theoretically feasible.
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J Clin Monit Comput · Apr 1998
Propagation of nitric oxide pools during controlled mechanical ventilation.
Infusing nitric oxide at a constant rate into a breathing circuit with intermittent mainstream flow causes formation of nitric oxide pools between successive breaths. We hypothesized that incomplete mixing of these pools can confound estimates of delivered nitric oxide concentrations. ⋯ Incomplete mixing of nitric oxide confounds estimates of delivered nitric oxide concentrations. When nitric oxide is infused at a constant rate into a breathing circuit, we doubt that any sampling site outside the patient's lungs can reliably predict delivered nitric oxide concentrations. Strategies to ensure complete mixing and representative sampling of nitric oxide should be considered carefully when designing nitric oxide delivery systems.
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J Clin Monit Comput · Apr 1998
Dynamic imaging of the pediatric upper airway during general anesthesia.
Video endoscopy can be easily performed in young children during general anesthesia. Airway patency can be directly qualified and then the video material can be transferred to a PC-based image analysis system for subsequent interactive teaching.
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Internet teleconferencing software can be used to hold "virtual" meetings, during which participants around the world can share ideas. A core group of anesthetic medical practitioners, largely consisting of the Society for Advanced Telecommunications in Anesthesia (SATA), has begun to hold regularly scheduled "virtual grand rounds." This paper examines currently available software and offers impressions of our own early experiences with this technology. Two teleconferencing systems have been used: White Pine Software CU-SeeMe and Microsoft NetMeeting. ⋯ While some effort is necessary to get these teleconferencing systems to work well, we have been using desktop conferencing for six months to hold virtual Internet meetings. The sound and video images produced by Internet teleconferencing software are inferior to dedicated point-to-point teleconferencing systems. However, low cost, wide availability, and ease of use make this technology a potentially valuable tool for clinicians and researchers.