Relation between bitter taste sensitivity and incidence or intensity of propofol injection pain

In human beings, pain and taste perception are two major sensory inputs. We investigated whether increasing bitter taste sensitivity would increase intensity or incidence of pain associated with propofol, and whether there is a relationship between bitter sensitivity and venepuncture pain.

One hundred (50 males, 50 females) American Society of Anesthesiologists Grade I adults undergoing elective surgery were included in this study. Determination of the taste thresholds employed a series of propylthiouracil solutions. The filter paper disk method was used to measure the taste threshold. A 20-G intravenous (i.v.) cannula was inserted in the dorsum of the non-dominant hand. Venepuncture pain was assessed by using a numerical rating scale (NRS; 0, no pain and 10, extreme pain). Propofol 10 mL (100 mg) was injected over 30 s. Assessment of pain with i.v. propofol was made using a 4-point scale: 0, no pain; 1, mild pain; 2, moderate pain; 3, severe pain.

The NRS score of venepuncture pain was 2.8 +/- 1.5. Sixty patients had pain during propofol injection. There was statistically significant correlation between bitter sensitivity and propofol injection pain, and between bitter sensitivity and venepuncture pain (P < 0.05).

We conclude that increased bitter taste sensitivity correlates with increased intensity or incidence of propofol injection pain and NRS of venepuncture pain.