INTRAVENOUS MORPHINE ATTENUATES PAIN INDUCED CHANGES IN SKIN BLOOD-FLOW IN NEWBORN-INFANTS

In a previous study we found that pain and discomfort caused a marked increase in skin blood flow in newborn infants, and that skin blood fl ow decreased after morphine. In this study we tested morphine effect o n the skin blood flow response to pain more systematically. Skin blood flow was measured using a laser Doppler technique during 19 percutane ous central venous catheter placements in 18 infants, 10 of whom recei ved intravenous morphine premedication. The mean +/- SD baseline skin blood flow was similar between the two groups: 22.5+/-9.5 ml 100 g(-1) min(-1) in the morphine group, and 23.7+/-8.0 ml 100 g(-1) min(-1) in the no-morphine group, respectively (p=n.s.). During PCVC placement i n the morphine treated group, skin blood flow remained low with minima l variability. The mean value was 22.6+/-7.7 ml 100 g(-1) min(-1) (p = n.s. compared to baseline). In 7/9 infants not treated with morphine skin blood flow increased dramatically during PCVC placement, while in two it did not. But the mean skin blood flow in this group of 9 infan ts during PCVC placement was 45.3+/-34 ml 100 g(-1) min(-1), an overal l change of 97% increase from the baseline. This was statistically sig nificant compared with the baseline and the morphine group value durin g PCVC insertion (p < 0.04). During the 45 min time period after PCVC placement, skin blood flow values between groups again were similar. W e conclude that morphine pretreatment for PCVC placement minimizes pai n-associated increases in skin blood flow. The issue of whether skin b lood flow changes could serve as measures of adequate analgesia needs to be evaluated with further studies.