Variables Exposed group Non-exposed group P-value
Frequency Percent Frequency Percent
Amount of blood loss
<500 ml 21 67.74 37 63.79 0.76
500-1000 ml 9 29.03 20 34.48  
 1000-1500 ml 1 3.23 1 1.72  
>1500 ml 0 0 0 0  
Total 31 100 58 100  
Type of anaesthesia         0.33
 General 16 51.61 27 46.55  
 Spinal 15 48.39 31 53.45  
 Total 31 100 58 100  
IV induction agent used         0.93
 Ketamine  7 43.75 12 44.44  
 Thiopental 9 56.25 15 55.56  
 Total  16 100 27 100  
Dose of reversal agent used          
<the recommended dose 4 25 7 25.93 0.65
 recommended dose 12 75 20 74.07  
>the recommended dose 0 0 0 0  
 Total 16 100 27 100  
Duration of surgery<1 hour 11 35.48 18 31.03 0.88
 1-2 hrs 20 64.52 40 68.97  
>2 hrs 0 0 0 0  
Total 31 100 58 100  
 Duration of anaesthesia<1 hour 11 35.48 18 31.03 0.88
 1-2 hrs 20 64.52 40 68.97  
>2 hrs 0 0 0 0  
Total 31 100 58 100  
Mean systolic blood pressure change 7.058 5-10% 8.11% 1-Jul 0.76
Table 2: Clinical factors which affect the incidence of post-operative nausea and vomiting, in Ayder referral hospital Mekelle, northern Ethiopia, 2013.