- Email: [email protected]
STEAM STERILISATION
661
maintain interest and ensure an attractive presentation, a lecturer is well advised to introduce matters of purely medical or scientific interest, but it is not reasonable to examine the student upon these matters. Nevertheless, we accept Miss Louden’s invitation to apply to become examiners, assuming that we could conscientiously discharge our duties according to our convictions. W. W. WALTHER Department of Pathology, Whipps Cross Hospital, C. C RAEBURN. RAEBURN KAEBURN. London, E.11. STEAM STERILISATION SIR,-Dr. Fallon (Sept. 9) finds that even downwarddisplacement steam sterilisers tend to damage nylon bags. Nylon bags are made in several thicknesses: a foil of gauge C 0’002 in. thick is the most effective. It is possible that Dr. Fallon used a foil of greater thickness than 0-002 in. The seal around the aluminium tube is quite effective, as described in my letter of July 8. The steam pressure in a downward-displacement steriliser may exceed 30 lb. per square inch. The high-vacuum steam steriliser seldom exceeds a steam pressure of 25 lb. per square inch in the chamber. If a small nylon pack is made up, sealed, with a few swabs inside, it is quite easy to place it in an all-glass anaerobic jar and exhaust the contained air with an Edwards high-vacuum pump. What happens to the nylon bag can be watched at all stages. A glass door to the high-vacuum steam steriliser would also enable one to see what was going on inside. After the tests in the exhausted anaerobic jar, the same trial packet may be placed in the high-vacuum steam steriliser and treated with a routine load, and subsequently examined for flaws, lack of sterility, &c. St. Margaret’s
Hospital, Epping.
FRANK NLARSH. FRANK MARSH. MARSCH.
FORMATION OF CALCULI
SIR,-In their interesting paper (Aug. 26) on the formation of calcium-oxalate calculi, Dr. Hodgkinson and his colleagues again draw attention to the interplay of the two hydrates of calcium oxalate in stone formation. According to them, calculi with large crystals develop by crystallisation and therefore require supersaturation (contributed to by hypercalcinuria), striated calculi develop by adsorption in a calcifiable matrix. Although they make it clear that striated calculi develop from only the monohydrate of calcium oxalate, they suggest that large crystals of this mineral are also common. This has not been my experience -large monohydrate crystals, though they do occur, are of great rarity. The relationship between the two hydrates deposits is an intriguing puzzle. Under all
in urinary tract normal circumstances of temperature and pressure calcium oxalate monohydrate is the stable crystalline form and the dihydrate is unstable. Why then do calculi composed of calcium oxalate " dihydrate-and envelope " crystalluria-occur at all ? A clue lies in the peculiar behaviour of the monohydrate when it crystallises out of urine. Instead of the pointed twinned crystals which develop in aqueous solutions, rounded deposits occur which resemble dumbbells or biscuits according to their orientation with respect to the observer. Similar deposits can be produced by the laboratory crystallisation of calcium oxalate in aqueous gelatin solutions.1 Morse2 has shown these rounded deposits to be microcrystalline aggregates and to be the first step in spherulite formation which is responsible for radial striation. The basic process is, however, still crystallisation, and 1. 2.
A. Pathology of the Formation of Calculi. Moynihan essay, 1952. H. D. Amer. Min. 391. 1936, 27, Morse, H. W., Donnay, J.
Carr, J.
prize
supersaturation is as necessary for it as crystallisation. The extreme ease with
for any other form of which spherulites can be grown from a large variety of minerals in many gelatinous media2 precludes any vital relationship between matrix and
crystals. All the evidence which indicates importance of a " calcifiable matrix " is concerned with calcium phosphate calculi.3 It is in these calculi that an acid mucopolysaccharide matrix has been identified 4 ; the mineral is apatite-the mineral of bone salt and all pathological calcifications-and moreover calcium phosphate is the only mineral forming fine-grained calculi in which radial striation is not found.
J. A. CARR.
Bury.
MANAGEMENT OF THIRD-STAGE COMPLICATIONS IN DOMICILIARY OBSTETRICS
SIR,-With regard to the correspondence arising from article of July 15, we should like to emphasise that in reviewing current practice we were struck by the constant similarity of management of third-stage complications regardless of the differing circumstances under which our
flying-squads operate. We put forward the view that in certain clearly defined circumstances another concept of management was feasible; this was substantiated by our results. We agree that domiciliary anaesthesia is safe providing there is available an expert obstetric anxsthetist with all his apparatus. In our case, we consider anesthesia to be safer in hospital. At the present time, the County of London is served by fourteen flying-squads each covering approximately two metropolitan boroughs. Twelve do not have an anxsthetist in the team; in the two that do he is not a consultant. With regard to the emotional upset of removing patients to hospital, one can say that all is well where obstetric matters go well. When dramatic complications occur, it is our experience that the relatives (and the patient if able to express her views) are only too pleased for hospital care; it is only for 24-48 hours. Furthermore, it relieves the overworked midwife of the exacting surveillance required for the initial 24 hours’ aftercare of these patients. A. C. FRASER St. James’ Hospital, E. E P P. W. T W TATFORD. Balham, London, S.W.12.
SIR,-We think that Dr. Fraser and Dr. Tatford have been unfairly and unnecessarily criticised for their fresh ideas on the function of the obstetric flying-squad in the management of third-stage complications in domiciliary obstetrics. This country is divided into those areas with and those without a flying-squad. In the latter the patient is often put into an ambulance whatever her condition and sent to hospital. In the former, the flying-squad often all treatment in the home. Dr. Fraser and Dr. completes Tatford have suggested a sane and commonsense compromise between these two extremes. The patient is seen in her home, is resuscitated, and then, if necessary, taken to hospital under expert supervision for any operative
procedure. No-one will
tion in
a
deny that the treatment of a third-stage complicahospital delivery is easier and safer than in domiciliary
The presence of an expert anaesthetist with complete apparatus, electric suction machine, and a tilting delivery bed is surely safer than open ether or chloroform in a private dwelling as suggested by Dr. Staddon (Sept. 2). Consequently we feel that the idea under discussion combines expert resuscita-
practice.
3. 4.
Carr, J. A. M.D. thesis, University of Durham, 1957. Howard, J. E., Carey, R. A., Rubin, P. S., Lewin, M. D. Trans. Amer. Phycns, 1949, 62, 264.
Ass.
maintain interest and ensure an attractive presentation, a lecturer is well advised to introduce matters of purely medical or scientific interest, but it is not reasonable to examine the student upon these matters. Nevertheless, we accept Miss Louden’s invitation to apply to become examiners, assuming that we could conscientiously discharge our duties according to our convictions. W. W. WALTHER Department of Pathology, Whipps Cross Hospital, C. C RAEBURN. RAEBURN KAEBURN. London, E.11. STEAM STERILISATION SIR,-Dr. Fallon (Sept. 9) finds that even downwarddisplacement steam sterilisers tend to damage nylon bags. Nylon bags are made in several thicknesses: a foil of gauge C 0’002 in. thick is the most effective. It is possible that Dr. Fallon used a foil of greater thickness than 0-002 in. The seal around the aluminium tube is quite effective, as described in my letter of July 8. The steam pressure in a downward-displacement steriliser may exceed 30 lb. per square inch. The high-vacuum steam steriliser seldom exceeds a steam pressure of 25 lb. per square inch in the chamber. If a small nylon pack is made up, sealed, with a few swabs inside, it is quite easy to place it in an all-glass anaerobic jar and exhaust the contained air with an Edwards high-vacuum pump. What happens to the nylon bag can be watched at all stages. A glass door to the high-vacuum steam steriliser would also enable one to see what was going on inside. After the tests in the exhausted anaerobic jar, the same trial packet may be placed in the high-vacuum steam steriliser and treated with a routine load, and subsequently examined for flaws, lack of sterility, &c. St. Margaret’s
Hospital, Epping.
FRANK NLARSH. FRANK MARSH. MARSCH.
FORMATION OF CALCULI
SIR,-In their interesting paper (Aug. 26) on the formation of calcium-oxalate calculi, Dr. Hodgkinson and his colleagues again draw attention to the interplay of the two hydrates of calcium oxalate in stone formation. According to them, calculi with large crystals develop by crystallisation and therefore require supersaturation (contributed to by hypercalcinuria), striated calculi develop by adsorption in a calcifiable matrix. Although they make it clear that striated calculi develop from only the monohydrate of calcium oxalate, they suggest that large crystals of this mineral are also common. This has not been my experience -large monohydrate crystals, though they do occur, are of great rarity. The relationship between the two hydrates deposits is an intriguing puzzle. Under all
in urinary tract normal circumstances of temperature and pressure calcium oxalate monohydrate is the stable crystalline form and the dihydrate is unstable. Why then do calculi composed of calcium oxalate " dihydrate-and envelope " crystalluria-occur at all ? A clue lies in the peculiar behaviour of the monohydrate when it crystallises out of urine. Instead of the pointed twinned crystals which develop in aqueous solutions, rounded deposits occur which resemble dumbbells or biscuits according to their orientation with respect to the observer. Similar deposits can be produced by the laboratory crystallisation of calcium oxalate in aqueous gelatin solutions.1 Morse2 has shown these rounded deposits to be microcrystalline aggregates and to be the first step in spherulite formation which is responsible for radial striation. The basic process is, however, still crystallisation, and 1. 2.
A. Pathology of the Formation of Calculi. Moynihan essay, 1952. H. D. Amer. Min. 391. 1936, 27, Morse, H. W., Donnay, J.
Carr, J.
prize
supersaturation is as necessary for it as crystallisation. The extreme ease with
for any other form of which spherulites can be grown from a large variety of minerals in many gelatinous media2 precludes any vital relationship between matrix and
crystals. All the evidence which indicates importance of a " calcifiable matrix " is concerned with calcium phosphate calculi.3 It is in these calculi that an acid mucopolysaccharide matrix has been identified 4 ; the mineral is apatite-the mineral of bone salt and all pathological calcifications-and moreover calcium phosphate is the only mineral forming fine-grained calculi in which radial striation is not found.
J. A. CARR.
Bury.
MANAGEMENT OF THIRD-STAGE COMPLICATIONS IN DOMICILIARY OBSTETRICS
SIR,-With regard to the correspondence arising from article of July 15, we should like to emphasise that in reviewing current practice we were struck by the constant similarity of management of third-stage complications regardless of the differing circumstances under which our
flying-squads operate. We put forward the view that in certain clearly defined circumstances another concept of management was feasible; this was substantiated by our results. We agree that domiciliary anaesthesia is safe providing there is available an expert obstetric anxsthetist with all his apparatus. In our case, we consider anesthesia to be safer in hospital. At the present time, the County of London is served by fourteen flying-squads each covering approximately two metropolitan boroughs. Twelve do not have an anxsthetist in the team; in the two that do he is not a consultant. With regard to the emotional upset of removing patients to hospital, one can say that all is well where obstetric matters go well. When dramatic complications occur, it is our experience that the relatives (and the patient if able to express her views) are only too pleased for hospital care; it is only for 24-48 hours. Furthermore, it relieves the overworked midwife of the exacting surveillance required for the initial 24 hours’ aftercare of these patients. A. C. FRASER St. James’ Hospital, E. E P P. W. T W TATFORD. Balham, London, S.W.12.
SIR,-We think that Dr. Fraser and Dr. Tatford have been unfairly and unnecessarily criticised for their fresh ideas on the function of the obstetric flying-squad in the management of third-stage complications in domiciliary obstetrics. This country is divided into those areas with and those without a flying-squad. In the latter the patient is often put into an ambulance whatever her condition and sent to hospital. In the former, the flying-squad often all treatment in the home. Dr. Fraser and Dr. completes Tatford have suggested a sane and commonsense compromise between these two extremes. The patient is seen in her home, is resuscitated, and then, if necessary, taken to hospital under expert supervision for any operative
procedure. No-one will
tion in
a
deny that the treatment of a third-stage complicahospital delivery is easier and safer than in domiciliary
The presence of an expert anaesthetist with complete apparatus, electric suction machine, and a tilting delivery bed is surely safer than open ether or chloroform in a private dwelling as suggested by Dr. Staddon (Sept. 2). Consequently we feel that the idea under discussion combines expert resuscita-
practice.
3. 4.
Carr, J. A. M.D. thesis, University of Durham, 1957. Howard, J. E., Carey, R. A., Rubin, P. S., Lewin, M. D. Trans. Amer. Phycns, 1949, 62, 264.
Ass.