Fast recoveries are essential when looking for a safe anaesthetic protocol to use on mice. Propofol is a short-acting anaesthetic agent, which provides a smooth, fast recovery. A recent study carried out in our laboratory showed that the intraperitoneal (i.p.) administration of propofol combined with a fast-acting opioid does not provide a sufficiently stable anaesthesia. In this experiment, we hypothesized that the additional application of medetomidine would increase muscle relaxation and analgesia. Fifty-four male CD1 mice, divided into six groups of five and three groups of eight, were used to test nine different combinations of propofol, medetomidine and fentanyl administered i.p. and reversed with atipamezole 30 min after induction. These combinations were composed in the following manner: propofol 75 mg/kg, medetomidine 1 and 2 mg/kg and fentanyl 0.1, 0.15 and 0.2 mg/kg. The depth of anaesthesia, loss of righting reflex, loss of pedal withdrawal reflex, pulse rate and respiratory rate were recorded along with the duration and quality of the recovery. The combination of propofol and medetomidine provided a predictable induction, hypnosis and muscle relaxation, but surgical anaesthesia (loss of pedal withdrawal reflex) was not achieved. The addition of fentanyl increased analgesia leading to surgical anaesthesia. We concluded that a combination of 75/1/0.2 mg/kg of propofol, medetomidine and fentanyl, respectively, is a safe, easy and reversible technique for i.p. anaesthesia in mice, providing a surgical window of 15 min and restraint for 30 min with a fast recovery.
SummaryThe combination of propofol and a rapid-acting opioid, such as fentanyl, sufentanil or remifentanil, is a relatively safe, total intravenous anaesthesia technique, commonly used in humans and which has been investigated in laboratory animals. The objective of this study was to evaluate these combinations for anaesthesia of mice by the intraperitoneal (i.p.) route. Sixty-seven mice, divided into groups of four, were used to test 28 combinations of propofol alone and propofol with fentanyl, sufentanil or remifentanil administered i.p. The dose ranges of drugs studied were propofol 50-200 mg/kg, fentanyl 0.2-0.4 mg/kg, sufentanil 0.05-0.1 mg/kg and remifentanil 0.2-1.0 mg/kg. The loss of righting reflex (RR) and the loss of pedal withdrawal reflex (PWR) were recorded along with the duration and quality of recovery. The results obtained in these studies were unpredictable. The same dose combinations of propofol and opioids were associated with different responses in different individuals. Higher doses did not induce loss of RR and PWR in all animals and were associated with high mortality rates. An adequate hypnotic level was only observed with higher doses of propofol. The synergistic effect of propofol and the opioids was not sufficient to allow surgical procedures. Animals that reached PWR loss showed tail rigidity, shaking limbs and scratched their heads with their forefeet. Higher opioid doses induced respiratory depression and higher death rates. The inconsistency between and within groups may be associated with the i.p. route. The results reported here show that the i.p. route is not appropriate for mouse anaesthesia using propofol alone or in combination with fentanyl, sufentanil or remifentanil.
The time, material, and staff-consuming nature of anatomy's traditional pen-and-paper assessment system, the increase in the number of students enrolling in medical schools and the ever-escalating workload of academic staff have made the use of computer-based assessment (CBA) an attractive proposition. To understand the impact of such shift in the assessment method, an experimental study evaluating its effect on students' performance was designed. Additionally, students' opinions toward CBA were gathered. Second-year medical students attending a Clinical Anatomy course were randomized by clusters in two groups. The pen-and-paper group attended two sessions, each consisting of a traditional sectional anatomy steeplechase followed by a theoretical examination, while the computer group was involved in two similar sessions conducted in a computerized environment. At the end of each of the computer sessions, students in this group filled an anonymous questionnaire. In the first session, pen-and-paper group students scored significantly better than computer-group students in both the steeplechase (mean ± standard deviation: 66.00 ± 14.15% vs. 43.50 ± 19.10%; P < 0.001) and the theoretical examination (52.50 ± 12.70% vs. 39.00 ± 21.10%; P < 0.001). In the second session, no statistically significant differences were found for both the steeplechase (59.50 ± 17.30% vs. 54.50 ± 17.00%; P = 0.085) and the theoretical examination (57.50 ± 13.70% vs. 54.00 ± 14.30%; P = 0.161). Besides, an intersession improvement in students' perceptions toward CBA was registered. These results suggest that, after a familiarization period, CBA might be a performance equivalent and student accepted alternative to clinical anatomy pen-and-paper theoretical and practical examinations. Anat Sci Educ 11: 124-136. © 2017 American Association of Anatomists.
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