Intramuscular Injections and Local Muscle Damage: An Experimental Study of the Effect of Injection Speed

Abstract

Physiological saline (0.9%) was administered intramuscularly into the longissimus dorsi muscle of rabbits (four animals per group) at different injection speeds (1 ml/sec. or 1 m1/10 sec.) and at different dose volumes (2 or 6 ml). The injection sites were examined post mortem 30 minutes after the injection. The same procedure was used for the administration of a solution of 1 % cis(Z)-clopenthixol, a neuroleptic drug, in 0.9% NaCl at speeds of 2 m1/2 sec., 2 m1/6 sec., 2 m1/20 sec., or 2 m1/60 sec. The injection sites of these rabbits were examined post martem 3 days after the injection. The muscle tissue at the injection sites was examined for macroscopic changes by serial sectioning. If a demarcated area of necrotic tissue was found, the necrotic area was dissected from the surrounding muscle tissue and weighed. Muscle tissue from rabbits receiving an injection of 0.9% NaCl was prepared for microscopic examination. In almost all rabbits given 0.9% NaCl the needle track was indicated by slight bleeding. In some of the rabbits which received 2 o r 6 ml of 0.9% NaCl over 2 or 6 sec., slight bleeding was also seen in the muscle tissue adjacent to the needle track. Since no further changes were seen, it is concluded that very fast injection of 0.9% NaCl only causes slight bleedingprobably fromdisruption of the local tissue. The needle track was identified microscopically by haemorrhages and disruption of muscle fibres. Muscle bundles were separated and muscles fibres were eosinophilic or vacuolated. In the rabbits given 1 % cis(Z)-clopenthixol, a well-demarcated area of necrotic muscle tissue was found at the injection sites. There was no difference between the mean weights of necrotic tissues from the groups given 2 ml over 2.20 or 60 sec. (mean weightsfS.E.M., 5.15f0.41, 4.6750.03, or 4.59f0.15 g, respectively). However, the mean weight of necrotic tissue from animals given 2 ml over 6 sec. (5.69f0.24 g) was significantly higher than that of the mean weights after injections given over 20 or 6Osec. From these findings it is concluded that injection speed is not an important factor for local damaging effect of intramuscular drug preparations. However, very slow injection may reduce the local damage but only slightly.

Preventing sciatic nerve injury from intramuscular injections: literature review

“…Whether a muscle is suitable for injection depends, in part, on the volume of injectate to be administered. It is suggested that the larger the volume, the greater the risk of injury to tissue (Svendsen 1983). It seems, then, that the closer the injection is to the SN, the greater the influence of volume on potential damage.…”

“…1995). In the absence of clear evidence (see Svendsen 1983, 1984, Mitchell & Whitney 2001), it may be prudent for nurses to follow the recommendation of a slow rate. Injecting slowly at least allows an opportunity to assess for verbal and non‐verbal responses and to withdraw the needle without further administration of medication should the client indicate an adverse effect, possibly limiting the extent of nerve damage.…”

Local Pain after Slow and Fast Intramuscular Injection of 0.9% Sodium Chloride in Human Volunteers

“…On fast injection of such drugs, the injected fluid probably spreads over a large area and causes discomfort. The experimental study by Svendsen (1983) in rabbits did not, however, support the belief that the injection speed of such preparations affects the size or type of the local lesion.…”

“…In a study with rabbits identical tissue changes were found after intramuscular injection of 2 ml saline given at speeds of 0.1 and 1.0 ml/sec. (Svendsen 1983). From these experiments it was expected that there would not be any difference in the reaction pattern of volunteers given saline injections with speeds of 0.2 and 1 .O ml/sec.…”

“…It is generally accepted that intramuscular injections should be given slowly in order to avoid local discomfort. A recent study with experimental animals has indicated that there is very little difference in the local tissue reaction after slow or fast injections (Svendsen 1983). However, studies with experimental animals cannot determine whether a fast injection causes more local discomfort than a slow injection.…”