Int J Emerg Med (2010) 3:105–113 Table 4 Comparisons of respiratory parameters for both treatment groups Variables Respiratory rate Pre-procedure Intra-procedure Post-procedure Oxygen saturation Pre-procedure Intra-procedure Post-procedure ETCO2 Pre-procedure Intra-procedure Post-procedure Propofol Mean (SD) 20.30 (4.90) 20.90 (5.31) 20.10 (5.28) 99.90 (0.45) 99.80 (0.89) 99.90 (0.45) 36.05 (6.57) 37.80 (4.96) 36.75 (5.46) Propofol Median (IQR) 19.50 (18.00, 23.50) 21.50 (16.50, 25.00) 20.00 (15.00, 24.00) 100.00 (100.00, 100.00) 100.00 (100.00, 100.00) 100.00 (100.00, 100.00) 38.50 (33.25, 40.00) 38.00 (34.25, 42.25) 38.00 (35.00, 40.00) Midazolam Mean (SD) 18.25 (5.00) 18.40 (4.60) 18.20 (3.59) 99.85 (0.49) 99.05 (2.01) 99.80 (0.69) 34.45 (7.82) 35.05 (8.97) 36.70 (7.20) Midazolam Median (IQR) 18.00 (14.00, 22.00) 18.50 (14.50, 21.75) 18.00 (16.00, 22.00) 100.00 (100.00, 100.00) 100.00 (99.25, 100.00) 100.00 (100.00, 100.00) 36.00 (33.25, 39.00) 39.50 (25.50, 40.75) 39.00 (33.50, 42.00) 109 p-value 0.574 0.082 0.554 0.226 0.106 0.215 0.558 0.775 0.606 cardiorespiratory compromise occurring during and after PSA are commonly reported. Reasons for the complications include inexperienced physicians administering the PSA, improper equipment for monitoring, wrong choice of drugs and presence of comorbidities that lead to the adverse events. Patients undergoing PSA must be closely and continuously monitored to avoid any progression into a deeper state of sedation [18, 19]. Should this occur, the actual purpose of PSA would be nullified. Monitoring can be achieved effectively through visual observation coupled with the use of a pulse oxymeter and a capnograph. The procedure can be carried out safely and non-invasively with the advent of new monitoring strategies. The use of a pulse oxymeter, for example, coupled with non-invasive moni- toring of blood pressure optimizes the comfort and care in patients receiving PSA [20]. The pulse oxymeter has been used to monitor the level of oxygenation. Since sedation can result in the emergence of apnea and hypoventilation, failure to detect these conditions may eventually lead to oxygen desaturation. The pulse oxymeter has been clinically shown to be a relevant tool to monitor the existence of oxygen desatura- tion. The capnograph is another very useful instrument for recognizing any ventilatory and circulatory problems that occur during sedation. A capnograph has the capacity to provide early warnings of apnea and detect the occurrence of respiratory depression, obstruction or laryngopasm through the monitoring of end tidal expiratory carbon dioxide (EtCO2), which can be accurately measured. Respiratory depression is said to take place when O2 saturation is <90 mmHg, EtCO2 is >50 mmHg or when there is an absence of EtCO2 waveform [21, 22]. Benzodiazepine such as midazolam has been widely used in many surgical procedures performed under local anesthesia. The use of midazolam has been well docu- mented to enhance patient comfort, improve operating conditions and most importantly, because of its amnesic properties, prevent patients from recalling unpleasant events during the procedure. In addition, midazolam acts indirectly as a gamma amino butyric acid agonist and is relatively cardio-respiratory safe. Once administered, it is rapid in onset and has a short duration of action, which makes midazolam a very popular drug of choice for PSA [23]. However, over the last few years, propofol has emerged quite rapidly as a good agent to be used in PSA by non-anesthesiologists especially in the ED. When given intravenously, the effect is almost immediate. Because of its short half-life, patients on propofol will recover rapidly. Propofol has a bronchodilating effect, which makes it an appropriate drug of choice for patients with bronchial asthma. Its anti-emetic characteristic gives an added advantage to minimize post-sedation nausea [24]. However, propofol reduces the mean arterial pressure (MAP), which makes it a rather poor choice in patients who develop hypotension, cardiorespiratory compromise or have head injuries. Apnea and painful injection are other disadvan- tages of this drug. It may also cause deep sedation and analgesia. Deep sedation is said to take place when a purposeful response is triggered with repeated stimuli, while moderate sedation is a purposeful response to light stimuli, e.g., verbal and tactile. Respiratory depression occurs mainly during deep sedation and not moderate sedation. In moderate sedation, the protective airway reflex is intact and thus reduces the risk of aspiration. Respiratory depression occurs in 19% of patients receiving propofol alone as compared to those who received fentanyl alone (20%), while a combination of midazolam with fentanyl causes respiratory depression in 23% of cases. Due to deep or over-sedation produced by propofol within the normal