Coffee break has no impact on laparoscopic skills: a randomized double-blinded placebo-controlled parallel-group trial

Abstract

Background: Coffee is a widely consumed beverage. Surgeons often drink coffee before performing surgery. Caffeine intake leads to tremor which might have a negative effect on surgeons' fine motor skills.

Methods: A double-blinded parallel-group trial was conducted in order to investigate if caffeinated coffee intake has a negative effect on laparoscopic skills and increases tremor, regardless of previous coffee consumption. 118 participants were selected during a congress of the German Society of Surgery. Exclusion criteria were immaturity and no given consent. Participants and investigators were blinded. Participants were randomized with a 1:1 allocation into interventional group receiving caffeinated coffee or placebo group receiving decaffeinated coffee. The motor skills were tested with two validated laparoscopic exercises at a laparoscopy simulator (LapSim®) before and 30 min after coffee intake. Data on influencing factors were recorded in a standardized questionnaire and tested for equal distribution in both groups. In both exercises four parameters were recorded: left and right hand path length and angular path. Their differences and the resulting effect scores were calculated for both groups as primary outcome to test which group showed greater improvement on the second round of exercises. Registration number DRKS00023608, registered retrospectively.

Results: Fifty nine subjects were assigned to each the interventional (54 analyzed) and placebo group (53 analyzed) with 11 drop outs. There was no significant difference between the placebo and interventional group in the two exercises in effect score 30 min after coffee intake [mean (SD); 38.58 (10.66) vs. 41.73 (7.40) and 113.09 (28.94) vs. 116.59 (25.63)]. A significant improvement from first to second measurement in the first exercise could be observed for both groups, demonstrating the training effect.

Conclusion: In our study, we verified that additional caffeinated coffee intake, e.g., during a coffee break, does not lead to deterioration of laparoscopic fine motor skills.

Keywords: Caffeine; Coffee; Fine motor skills; Laparoscopy; Surgery; Tremor.

Fig. 1

Flowchart of the trial design. After conducting the first round of performing exercises, the subjects were randomized into control (upper boxes) and interventional group (lower boxes). Two cups of coffee were defined as 340 ml

Fig. 2

CONSORT 2010 flow diagram of the trial

Fig. 3

No influence of caffeinated coffee on laparoscopic hand skills. Statistical analysis was performed using unpaired two-sided t test. Total effect score is the combined classified difference in path length and angular path of each participant in arbitrary units (AU). a No significant difference in hand movement for ‚Lifting and Grasping ‘ [intervention 41.73 (7.40) vs. control 38.58 (10.66); p = 0.079]. b No significant difference in hand movement for ‚Clip Applying ‘ [intervention 116.59 (25.63) vs. control 113.09 (28.94); p = 0.511]

Fig. 4

Comparison of first to second round of ‘Lifting and Grasping’ exercise. Shorter path length and smaller angular path mean more manual dexterity. Statistical analysis was made using two-sided paired t testing, **p < 0.01, ***p < 0.001. a—Placebo group. a1 Path length. Subjects improved significantly from first to second round in path length [LIPL 3.00 (1.49) vs. 2.19 (0.72), p < 0.001; RIPL 2.70 (1.31) vs. 1.98 (0.58), p < 0.001]. a2 Angular path. Subjects improved significantly from first to second round in angular path [LIAP 652.40 (327.33) vs. 483.01 (173.34), p < 0.001; RIAP 577.95 (287.91) vs. 421.63 (134.09), p < 0.001]. b—Interventional group. b1 Path length. Subjects improved significantly from first to second round in path length [LIPL 2.66 (0.95) vs. 2.23 (0.78), p = 0.001; RIPL 2.44 (± 0.93) vs. 2.08 (0.88), p = 0.003]. b2 Angular path. Subjects improved significantly from first to second round in angular path [LIAP 579.10 (211.23) vs. 472.78 (182.74), p < 0.001; RIAP 511.16 (190.42) vs. 421.86 (156.45), p < 0.001]

Fig. 5

Comparison of first to second round of ‘Clip Applying’ exercise. Shorter path length and smaller angular path mean more manual dexterity. Statistical analysis was made using two-sided paired t testing. a—Placebo group. a1 Path length. Subjects did not improve significantly from first to second round in path length [LIPL 3.00 (2.93) vs. 2.70 (3.20), p = 0.535; RIPL 3.29 (3.00) vs. 3.21 (3.16), p = 0.863]. a2 Angular path. Subjects did not improve significantly from first to second round in angular path [LIAP 568.36 (625.53) vs. 487.02 (624.05), p = 0.391; RIAP 606.46 (615.30) vs. 555.53 (629.24), p = 0.577]. b—Interventional group. b1 Path length. Subjects did not improve significantly from first to second round in path length [LIPL 2.31 (1.63) vs. 2.36 (2.35), p = 0.865; RIPL 2.89 (1.92) vs. 3.16 (3.36), p = 0.560]. b2 Angular path. Subjects did not improve significantly from first to second round in angular path [LIAP 440.46 (360.70) vs. 433.83 (506.64), p = 0.929; RIAP 507.41 (366.95) vs. 558.65 (677.91), p = 0.577]