- Email: [email protected]
VIABILITY OF SKIN FLAPS
1385 increase in temperature, and S.C.P.K. rise supports the contention by Viby Mogensen et al.3 that ketamine is contraindicated in potential M.H. victims. The gradual onset and mildness of symptoms in this case might indicate that ketamine is a weak triggering agent. During a more prolonged anxsthesia and in combination with other triggering agents, a fulminant M.H. might have developed. Department of Anaesthesia, S. ROERVIK Rikshospitalet, Oslo, Norway. J. STOVNER.
VIABILITY OF SKIN FLAPS
SIR,-You discussed1 the design of skin flaps, Milton’s experiments2 on pigs, and his interpretation of his own results, suggesting that the viability of a skin flap was dictated by its area/width ratio, rather than by its length/ width ratio, as had previously been widely held. However, Milton’s interpretation of his own results can be criticised on two grounds. Firstly, his interpretation does not conform to the results he actually reported, for the following reason. The area of a rectangle equals the length multiplied by the width. Thus, in order to maintain a constant area/ width ratio, the length must be constant. Milton’s results, however, as he himself said, showed that the surviving length of a flap increases with increasing width, but not sufficiently to maintain a constant length/width ratio. Secondly, Milton’s work was carried out on rectangular flaps only, and it appears unjustified to make predictions about the area of flaps without investigating flaps of other TABLE
I-LENGTH/WIDTH
RATIO
TABLE III-SURVIVING LENGTHS OF FLAPS
flaps (table 11), the difference being again statistically highly significant (F ratio =59-94, P < 0’001). Indeed, the only constant relationship noted was that between the surviving lengths of the triangular flaps compared to their comparative rectangular flaps, within the limits of experimental error, these lengths being the same (table ill). From this work it appears that a modification of Milton’s hypothesis may be more accurate: " Flaps made under similar conditions of blood supply survive to the same length regardless of width and shape." Ear, Nose, and Throat Infirmary, Myrtle Street, Liverpool L7 7DF.
P. M. STELL.
AND BONE PAIN OF METASTATIC BREAST CANCER
PROLACTIN, PROSTAGLANDIN,
SiR—The observation by Dr Horrobin and his colleagues (Nov. 9, p. 1154) that prolactin stimulates endogenous prostaglandin synthesis may provide an explanation for the rapid relief from bone pain noted in some patients cancer treated with levodopa.1 prolactin secretionand this may result in a lowering of prostaglandin synthesis by bony metastases. As it has been suggested that prostaglandins may mediate the osteolytic effect of bony metastases3 and
with metastatic breast
Levodopa
suppresses
influence the response of endocrine tissues to hormonal stimulation,4 reduction in prostaglandin levels through prolactin suppression could result in pain relief. This view is further supported by the observation that indomethacin, an inhibitor of tissue prostaglandin synthesis,5I) can afford rapid relief from bone pain in patients with metastatic breast cancer 4 and haematological neoplasms.6 Scripps Clinic and Research Foundation, La Jolla, California 92037, U.S.A.
shapes, such as the triangle, which are commonly used in plastic surgery. I have carried out experiments similar to those of Milton, using the abdominal skin of the pig. Forty rectangular flaps in all were raised on 10 pigs; there were four groups of ten flaps, with bases of 20, 30, 40, and 50 mm., respectively. Rectangular flaps for comparison were raised on the opposite side of the animal, based correspondingly with bases of the same size. Both rectangular and triangular flaps were of such a length that the distal part would become necrotic, and their position and distribution as regards size were randomised. The pigs were inspected on the fifth day, and the surviving lengths and areas of the flaps measured. The results showed, as did Milton’s, that the surviving length increased with increasing width so that the length/ width ratio of the surviving part of the flap fell, the differ-
were
ence
being statistically highly significant (F ratio=6-123,
P< 0-001)
(table i).
width differed widely 1. 2.
Furthermore, the ratio of area to between rectangular and triangular
Lancet, 1970, ii, 405. Milton, S. H. Br. J. Surg. 1970, 57, 502.
PETER V. SACKS.
IRON AND INFECTION IN THE NEWBORN SiR,-Your editorial (Aug. 10, p. 325) and the paper by Dr Masawe and others (p. 314) prompt us to draw attention to our experience of gram-negative sepsis in newborn infants given iron-dextran injections soon after birth.7 These injections were given to Polynesian newborns as prophylaxis against iron deficiency in later infancy, and were effective in this aim. In 1970, 1971, and 1972, a high incidence of gramnegative sepsis neonatorum confined to Polynesian babies receiving these injections was noted. The injections were stopped, and there was a dramatic fall in the incidence of this disease. We intend to report these findings fully later. We are convinced of a relationship between parenteral iron-dextran and serious infections in these newborns, and we would warn against this method of treatment or prophylaxis. 1. 2. 3. 4. 5. 6. 7.
Minton, J. P. Cancer, 1974, 33, 358. Turkington, R. W. J. clin. Endocr. Metab. 1972, 34, 306. LiVolsi, V. A. Lancet, 1973, ii, 263. Stoll, B. A. ibid. 1973, ii, 384. Flower, R. J., Vane, J. R. Nature, 1972, 240, 410. Brodie, G. N. Lancet, 1974, i, 1160. Barry, D. M. J., Reeve, A. W. N.Z. med. J. 1973, 78, 376.
VIABILITY OF SKIN FLAPS
SIR,-You discussed1 the design of skin flaps, Milton’s experiments2 on pigs, and his interpretation of his own results, suggesting that the viability of a skin flap was dictated by its area/width ratio, rather than by its length/ width ratio, as had previously been widely held. However, Milton’s interpretation of his own results can be criticised on two grounds. Firstly, his interpretation does not conform to the results he actually reported, for the following reason. The area of a rectangle equals the length multiplied by the width. Thus, in order to maintain a constant area/ width ratio, the length must be constant. Milton’s results, however, as he himself said, showed that the surviving length of a flap increases with increasing width, but not sufficiently to maintain a constant length/width ratio. Secondly, Milton’s work was carried out on rectangular flaps only, and it appears unjustified to make predictions about the area of flaps without investigating flaps of other TABLE
I-LENGTH/WIDTH
RATIO
TABLE III-SURVIVING LENGTHS OF FLAPS
flaps (table 11), the difference being again statistically highly significant (F ratio =59-94, P < 0’001). Indeed, the only constant relationship noted was that between the surviving lengths of the triangular flaps compared to their comparative rectangular flaps, within the limits of experimental error, these lengths being the same (table ill). From this work it appears that a modification of Milton’s hypothesis may be more accurate: " Flaps made under similar conditions of blood supply survive to the same length regardless of width and shape." Ear, Nose, and Throat Infirmary, Myrtle Street, Liverpool L7 7DF.
P. M. STELL.
AND BONE PAIN OF METASTATIC BREAST CANCER
PROLACTIN, PROSTAGLANDIN,
SiR—The observation by Dr Horrobin and his colleagues (Nov. 9, p. 1154) that prolactin stimulates endogenous prostaglandin synthesis may provide an explanation for the rapid relief from bone pain noted in some patients cancer treated with levodopa.1 prolactin secretionand this may result in a lowering of prostaglandin synthesis by bony metastases. As it has been suggested that prostaglandins may mediate the osteolytic effect of bony metastases3 and
with metastatic breast
Levodopa
suppresses
influence the response of endocrine tissues to hormonal stimulation,4 reduction in prostaglandin levels through prolactin suppression could result in pain relief. This view is further supported by the observation that indomethacin, an inhibitor of tissue prostaglandin synthesis,5I) can afford rapid relief from bone pain in patients with metastatic breast cancer 4 and haematological neoplasms.6 Scripps Clinic and Research Foundation, La Jolla, California 92037, U.S.A.
shapes, such as the triangle, which are commonly used in plastic surgery. I have carried out experiments similar to those of Milton, using the abdominal skin of the pig. Forty rectangular flaps in all were raised on 10 pigs; there were four groups of ten flaps, with bases of 20, 30, 40, and 50 mm., respectively. Rectangular flaps for comparison were raised on the opposite side of the animal, based correspondingly with bases of the same size. Both rectangular and triangular flaps were of such a length that the distal part would become necrotic, and their position and distribution as regards size were randomised. The pigs were inspected on the fifth day, and the surviving lengths and areas of the flaps measured. The results showed, as did Milton’s, that the surviving length increased with increasing width so that the length/ width ratio of the surviving part of the flap fell, the differ-
were
ence
being statistically highly significant (F ratio=6-123,
P< 0-001)
(table i).
width differed widely 1. 2.
Furthermore, the ratio of area to between rectangular and triangular
Lancet, 1970, ii, 405. Milton, S. H. Br. J. Surg. 1970, 57, 502.
PETER V. SACKS.
IRON AND INFECTION IN THE NEWBORN SiR,-Your editorial (Aug. 10, p. 325) and the paper by Dr Masawe and others (p. 314) prompt us to draw attention to our experience of gram-negative sepsis in newborn infants given iron-dextran injections soon after birth.7 These injections were given to Polynesian newborns as prophylaxis against iron deficiency in later infancy, and were effective in this aim. In 1970, 1971, and 1972, a high incidence of gramnegative sepsis neonatorum confined to Polynesian babies receiving these injections was noted. The injections were stopped, and there was a dramatic fall in the incidence of this disease. We intend to report these findings fully later. We are convinced of a relationship between parenteral iron-dextran and serious infections in these newborns, and we would warn against this method of treatment or prophylaxis. 1. 2. 3. 4. 5. 6. 7.
Minton, J. P. Cancer, 1974, 33, 358. Turkington, R. W. J. clin. Endocr. Metab. 1972, 34, 306. LiVolsi, V. A. Lancet, 1973, ii, 263. Stoll, B. A. ibid. 1973, ii, 384. Flower, R. J., Vane, J. R. Nature, 1972, 240, 410. Brodie, G. N. Lancet, 1974, i, 1160. Barry, D. M. J., Reeve, A. W. N.Z. med. J. 1973, 78, 376.