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Automated apparatus for exchange transfusion
1 60
Editorial correspondence
Autonlated apparatus for exchange transfusion To the Editor: Thank you for the interesting article by Goldman and Tu t about the automated method for exchange trar~sfusion. We have also devised almost the same apparatus with a two-site technique, utilizing an Atom infusion pump (Model 501). With this apparatus we have successfully performed exchange transfusions 21 times in 13 infants with birth weights ranging from 530 to 3368 gm. None had any serious complications. We recorded the variation in blood pressure of premature infants during the exchange transfusions using a temporal artery for BP monitoring, a radial or brachial artery for exsanguination, and a cephalic or basilic vein for infusion. No significant change in BP was observed before, during, or after the transfusion. We also measured the exchange rate with this technique, by counting a serial change of fetal red cells to adult cells during the exchange transfusion. Compared with Diamond's method, we found this method much better in the efficacy of exchange rate, especially in the early stage of the transfusion. We also believe that this method might be an easier, safer, and more effective modification of several traditional techniques for exchange transfusion.
Masahisa Funato, M.D. Seiichi Shimada, M.D. Hiroshi TamaL M.D. Mayumi Yamamoto. ],I.D. Hideo Taki. M.D. Yodogawa Christian Hospital Osaka. Japan 533 REFERENCE 1. Goldman SL, Tu HC: Automated method for exchange transfusion: A new modification. J PEmATR 102:119, 1983.
Pharmacokinetics of tobramycin in neonates
The Journal ofPediatrics January1984
tions are rarely manifested clinically. Nevertheless, the need for immediate high serum concentrations of aminoglycosides needs to be emphasized for the occasional patient who truly has bacterial sepsis.
Melvin L Marks, M.D. Director. Pediatric Infectious Disease Program Professor of Pediatrics Adjunct Professor of Microbiology/Immunology University of Oklahoma Oklahoma Oty, OK 73190 REFERENCES 1. Arbeter AM, Saccar CL, Eisner S, Sarni E, Yaffe S J: Tobramycin sulfate elimination in premature infants. J PEmATR 103:131, 1983. 2. Nahata MC, Powell DA, Gregoire RP, McCleod RE, Menke JA, Bickers RG, Glazer JP: Tobramycin kinetics in newborn infants. J PEDIATR 103:136, 1983. 3. Marks S, Marks MI, Dupont C, Hammerberg S. Evaluation of three antibiotic programs in newborn infants. Can Med Assoc J 118:659, 1978.
Rep& To the Editor: Although we use aminoglycosides frequently, and have the impression of adequate antimicrobial activity, our impression may certainly be affected by the large number of noninfected patients with "'suspected sepsis" treated and the common use of a B-laetam antibiotic in combination with the aminoglycoside. Unfortunately, in our study we were unable to obtain dose 1 pharmacokinetics. It would be reasonable to expect that a dose two to three times higher than usual might be necessary as a loading dose. However, until data (including safety) are available, there does not appear to be any accumulated clinical experience of treatment failures. Furthermore, in the article Marks quotes, he states that " . . . several samples approaching toxic concentration for each of the three aminoglycosides were noted despite the administration of conventional doses in infants with normal renal functions." Because of the marked variable elimination in the premature infant, we believe the dosage schedule described in our paper is appropriate until first-dose pharmacokinetics can be carefully studied.
To the Editor: The observations about tobramycin pharmacokinetics in newborn infants1'2 are interesting and reaffirm the need for monitoring serum concentrations of aminoglycosides in this age group. Neither study, however, mentions the fact that a 2.5 mg/kg dose rarely achieves therapeutic serum concentrations within the therapeutic range after the initial dose) In fact, our studies demonstrated that two or three doses of tobramycin are often required before conventional therapeutic serum concentrations were achieved in many of these patients. Because the dosage intervals suggested may be as high as 12 to 24 hours, it is possible that subtherapeutic concentrations may be present during the first 8 to 48 hours of therapy. Because the vast majority of aminoglycoside usage in newborns is for "suspected sepsis" that is subsequently not microbiologically confirmed, these subtherapeutic concentra-
Allan M. Arbeter, M.D. Director, Ambulatory Pediatrics Albert Einstein Medical Center Philadelphia, PA 19141 Consuelo L. Saccar. Pharm.D. Thomas Jefferson University Hospital Philadelphia, PA 19107
Rep& To the Editor: Although we recognize the importance of the observation by Marks et al., ~ we do not agree that their data confirm that all patients will have subtherapeutic peak serum concentrations after an initial dose of 2.5 mg/kg.
Editorial correspondence
Autonlated apparatus for exchange transfusion To the Editor: Thank you for the interesting article by Goldman and Tu t about the automated method for exchange trar~sfusion. We have also devised almost the same apparatus with a two-site technique, utilizing an Atom infusion pump (Model 501). With this apparatus we have successfully performed exchange transfusions 21 times in 13 infants with birth weights ranging from 530 to 3368 gm. None had any serious complications. We recorded the variation in blood pressure of premature infants during the exchange transfusions using a temporal artery for BP monitoring, a radial or brachial artery for exsanguination, and a cephalic or basilic vein for infusion. No significant change in BP was observed before, during, or after the transfusion. We also measured the exchange rate with this technique, by counting a serial change of fetal red cells to adult cells during the exchange transfusion. Compared with Diamond's method, we found this method much better in the efficacy of exchange rate, especially in the early stage of the transfusion. We also believe that this method might be an easier, safer, and more effective modification of several traditional techniques for exchange transfusion.
Masahisa Funato, M.D. Seiichi Shimada, M.D. Hiroshi TamaL M.D. Mayumi Yamamoto. ],I.D. Hideo Taki. M.D. Yodogawa Christian Hospital Osaka. Japan 533 REFERENCE 1. Goldman SL, Tu HC: Automated method for exchange transfusion: A new modification. J PEmATR 102:119, 1983.
Pharmacokinetics of tobramycin in neonates
The Journal ofPediatrics January1984
tions are rarely manifested clinically. Nevertheless, the need for immediate high serum concentrations of aminoglycosides needs to be emphasized for the occasional patient who truly has bacterial sepsis.
Melvin L Marks, M.D. Director. Pediatric Infectious Disease Program Professor of Pediatrics Adjunct Professor of Microbiology/Immunology University of Oklahoma Oklahoma Oty, OK 73190 REFERENCES 1. Arbeter AM, Saccar CL, Eisner S, Sarni E, Yaffe S J: Tobramycin sulfate elimination in premature infants. J PEmATR 103:131, 1983. 2. Nahata MC, Powell DA, Gregoire RP, McCleod RE, Menke JA, Bickers RG, Glazer JP: Tobramycin kinetics in newborn infants. J PEDIATR 103:136, 1983. 3. Marks S, Marks MI, Dupont C, Hammerberg S. Evaluation of three antibiotic programs in newborn infants. Can Med Assoc J 118:659, 1978.
Rep& To the Editor: Although we use aminoglycosides frequently, and have the impression of adequate antimicrobial activity, our impression may certainly be affected by the large number of noninfected patients with "'suspected sepsis" treated and the common use of a B-laetam antibiotic in combination with the aminoglycoside. Unfortunately, in our study we were unable to obtain dose 1 pharmacokinetics. It would be reasonable to expect that a dose two to three times higher than usual might be necessary as a loading dose. However, until data (including safety) are available, there does not appear to be any accumulated clinical experience of treatment failures. Furthermore, in the article Marks quotes, he states that " . . . several samples approaching toxic concentration for each of the three aminoglycosides were noted despite the administration of conventional doses in infants with normal renal functions." Because of the marked variable elimination in the premature infant, we believe the dosage schedule described in our paper is appropriate until first-dose pharmacokinetics can be carefully studied.
To the Editor: The observations about tobramycin pharmacokinetics in newborn infants1'2 are interesting and reaffirm the need for monitoring serum concentrations of aminoglycosides in this age group. Neither study, however, mentions the fact that a 2.5 mg/kg dose rarely achieves therapeutic serum concentrations within the therapeutic range after the initial dose) In fact, our studies demonstrated that two or three doses of tobramycin are often required before conventional therapeutic serum concentrations were achieved in many of these patients. Because the dosage intervals suggested may be as high as 12 to 24 hours, it is possible that subtherapeutic concentrations may be present during the first 8 to 48 hours of therapy. Because the vast majority of aminoglycoside usage in newborns is for "suspected sepsis" that is subsequently not microbiologically confirmed, these subtherapeutic concentra-
Allan M. Arbeter, M.D. Director, Ambulatory Pediatrics Albert Einstein Medical Center Philadelphia, PA 19141 Consuelo L. Saccar. Pharm.D. Thomas Jefferson University Hospital Philadelphia, PA 19107
Rep& To the Editor: Although we recognize the importance of the observation by Marks et al., ~ we do not agree that their data confirm that all patients will have subtherapeutic peak serum concentrations after an initial dose of 2.5 mg/kg.