Int J Emerg Med (2010) 3:105–113 reach the pre-procedural level. In the midazolam group, the heart rate was also found to be reduced during the procedure stage. The mean heart rate during the procedure was 79.65 (16.69) and the mean before the procedure (SD) was 85.45 (13.38). The p value for both groups was 0.795. End tidal carbon dioxide level Capnography could provide an accurate assessement of various aspects of respiratory functions, which included real-time ventilatory status, endotracheal tube placement and function, ventilatory circuit disconnection and airway leaks. This study utilized nasal prong microstream devices, which measured respiratory gas concentration remotely by aspirating a small sample of gas from the breathing circuit through tubing to a sensor located inside the monitor. The partial pressure of carbon dioxide was kept constant between the level of 35 mmHg to 45 mmHg. Any adverse changes or complications in respiratory functions that arise can be easily detected through capnography. Early detection would ensure an immediate intervention on the patient [30]. In this study, the end tidal carbon dioxide level in the propofol group did not show much variation between the pre- and intra-procedural readings. The means (SD) of pre- procedural and intra-procedural end tidal carbon dioxide levels were 36.05 (6.57) and 37.80 (4.96), respectively. The post-procedural mean was 36.75 (5.46) with an intra- procedural p value of 0.775. In the midazolam group, the mean end tidal carbon dioxide levels both pre-procedure and intra-procedure were 34.45 (7.82) and 35.05 (8.97), respectively (p = 0.77). There were no marked differences in end tidal carbon dioxide readings between these two drugs. This was because the doses of both drugs used were adequately safe, and additional use of capnography moni- toring of the end tidal carbon dioxide level could provide early warning should there be evidence of apnea or hypoventilation. Interventions including repositioning of the airway can be carried out if there is evidence of reduction of partial pressure of carbon dioxide. Jennifer et al. pointed out that capnography is capable of providing important data regarding airway permeability, cardiac and circulatory function and ventilator performance, apart from its ability to evaluate alveolar ventilation. The use of capnography could replace the need to analyze ABG in a non-invasive manner [31]. It is important to emphasize that all subjects in both groups A and B were provided with continuous oxygen via nasal prong devices throughout the PSA. In a review done by Vargo, he has stressed the significance of unrecognized respiratory difficulty and hypoxemia as a major factor contributing to morbidity and mortality among patients with PSA in the ambulatory setting. To overcome these potential risks, he strongly 111 recommended the use of capnography, which can monitor and detect any evidence of respiratory compromise early on with the combined use of pulse oxymetry. In all the domains of recorded vital signs, it was found to be insignificant, as shown by the p value of >0.005 on Mann-Whitney U test. For the respiratory rate in male subjects, during the procedure a slight reduction of respiratory rate was observed in the midazolam group from a mean value of 19.37 (4.96) per minute to 19.12 (4.36) (p =0.148). There was no similar reduction among males in the propofol group using stratified Mann-Whitney analysis. The time interval to discharge for male subjects in the propofol group was observed to be shorter when compared to the midazolam group with a mean (SD) value of 30.33 (12.46) as compared to 59.06 (22.7), respectively, with a p value of 0. 001. In female subjects, the mean (SD) values for the propofol and midazolam were 26.00 (4.18) and 122.50 (28.16), respectively (p = 0.001). There was no significant change found when the data were stratified further to look at the effect of the confounder (sex) on the differences between both propofol and midazolam. Other studies had shown similar patterns of outcome [32, 33]. Limitations of the study Several limitations have been identified in this study. 1. Generally the size of the sample recruited was judged to be small. There were reasons for such a small sample gathered. This study was carried out for a period of 1 year as part of the clinical exposure for the completion of the Master program; the sample size was reduced to an acceptable 40 subjects and had received approval from the hospital ethics committee. The subjects were then subdivided equally into two groups comprising 20 subjects each, further reducing the size and thus the power of this study. 2. During the process of administration of the drugs under study, the operators were aware of the drugs that were given to the patients when the envelope was opened. The operator could easily recognize the types of drugs given by the different sizes of ampules, the color of the ampules, the inscription on the ampule and the quantity of the drug in the ampule. This method did not actually protect the anonymity of the drug administered and could possibly have resulted in some level of bias. 3. As a result of the small sample size, the parametric analysis could not be carried out. The data were analyzed using the non-parametric Mann-Whitney U and Kruskal-Wallis analyses. 4. As the main objective of the study was to observe the outcomes of the drugs used—propofol and midazolam