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Objective: To develop an ergonomically designed computerized recordkeeping tool for anesthesiologists that allows the clinician to maintain visual contact with the patient while performing recordkeeping.Methods: To simplify the human interface software, we developed two general use software components. All purpose menu type 1 (APM1) was used for entering events using a tree structured menu. APM1 was designed to adapt to the limits of human memory, by using Miller's rule of 7 to guide the input process. APM1 can be considered to be a three-dimensional table list consisting of 7 vertical and 7 horizontal choices, which has further 5 tree-structured divergences. APM1 is also completely configurable by the user. All purpose menu 2 (APM2) was used to implement the system-initiated human interface where the system will prompt the user by voice for each entry. When users touch a key on APM1 and APM2, the system was designed to respond with a voice prompt. A touch-screen was also utilized and designed to fit the anesthesia machine. The screen is equipped with a small speaker for voice response and a microphone for voice recognition. The positions of the screen are adjustable supported by a long flexible limb (85 cm).Results: After improving the design, systems were assembled for 10 operating rooms. Of the multiple features of the VOCAAR user interface, the following were well accepted by users and employed daily: touch-screen input, and voice response. The noncompulsory use rate was 87% during the initial 2 weeks, increased to 94% after 2 weeks and 100% after two months. The mean sound emission by voice response (n = 10, mean +/- SD) was 8.2 +/- 2.3 dB at the main anesthetist site (35 cm from the speaker mounted on the touch-screen), 2.2 +/- 1.3 dB at the staff site (1.5 m from the touch-screen), which was only audible for anesthesiologist but for surgeon.Discussion: An EARK system was designed to allow the user to maintain visual contact with the patient while performing recordkeeping tasks. The combination of a mobile touch screen and voice response/recognition facilitated the design goals of the system. Although the system has enjoyed universal clinical acceptance, the voice functions remain too limited to satisfy the needs of a completely handsfree user interface. Enhancements to voice recognition technology will offer the potential for improved functionality. Additional research is also needed to better define the relationship between vigilance and visual contact with the patient. [ABSTRACT FROM AUTHOR]

Objective. In order to predict the partial pressure of volatile anesthetics in brain tissue, we developed a pharmacokinetic simulation model suitable for real time application. The accuracy of this model was examined by comparing the predicted values against measured values for blood sampled from the internal jugular vein, which was used as a measure of the partial pressure in the brain. Methods. Our model consists of six compartments: alveoli, arterial blood, a group of vessel-rich organs (VRG), muscle, fat, and venous blood. A volatile anesthetic, sevoflurane partial pressure in each compartment were calculated using the parameters of volume, blood flow, and solubility for each tissue as reported in previous studies. Simulated sevoflurane partial pressures in VRG were considered to reflect those in the brain. We studied 11 patients undergoing elective abdominal surgery or mastectomy. Sevoflurane was maintained at a concentration of 3% (by vaporizer setting) for 25 min. Sampling points were at 0 min (before sevoflurane administration) and 1, 2, 4, 9, 16, and 25 min after the start of inhalation. We measured the sevoflurane partial pressure in inspiratory gas (PIS), in end-expiratory gas (PETS), in arterial blood (PaS), and in internal jugular vein blood (PjS). These values were compared against those for the simulated brain (PBSsim). Results. The sevoflurane partial pressures increased, in order from least rapid to most rapid, as follows: PjS, PBSsim, PaS, PETS, and PIS. The differences between PjS and PBSsim were significantly smaller than those between PjS and PETS at all sampling points. PBSsim did not differ significantly from PjS at any sampling points after 4 min of inhalation, while PETS differed significantly from PjS at all sampling points. Conclusion.We conclude that our model is clinically useful for predicting sevoflurane partial pressure in the brain, assuming that PjS reflects the sevoflurane partial pressure in the brain. [ABSTRACT FROM AUTHOR]

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). Before anesthesia, VCO2/BSA and VO2/BSA were 97.7 +/- 11.3 and 116.0 +/- 10.0 ml x min(-1) x m(-2), respectively. During anesthesia, they fell to 72.3 +/- 6.0 and 89.8 +/- 7.6 ml x min(-1) x m(-2), respectively (p < 0.05). VCO2/BSA increased to 96.0 +/- 11.1 at pneumoperitoneum (p < 0.05) and increased further to 126.1 +/- 11.0 ml x min(-1) x m(-2) at Surgery. It fell to 111.7 +/- 10.9 ml x min(-1) x m(-2) Postsurgery. VO2/BSA remained unchanged during pneumoperitoneum. 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. [ABSTRACT FROM AUTHOR]