Human β-endorphin level determination

Volume 103 Number 5

Editorial correspondence

833

To the Editor: We confirm the report by Wilcox et al. 1 presenting range-gated pulsed Doppler ultrasonography as a diagnostic tool to detect patent ductus arteriosus (PDA) in preterm infants. We performed flow velocity studies on the anterior cerebral artery using an ATL Mark 500 Doppler sonograph? In eight preterm infants (birth weight 600 to 2300 gin) with clinical indications of PDA, the diameter of the PDA could be measured either at surgical intervention (in five) or at autopsy (in three). Zero or negative diastolic flow was noted in four infants with a large PDA (diameter 4 mm or more), whereas in the other four infants, a small PDA was combined with positive diastolic flow. After surgical repair, diastolic flow increased in all infants, without evidence of negative flow. Nevertheless, one infant who developed septic shock four days after surgery showed negative flow again, which became promptly positive after continuous infusion of dopamine 15 /zg/kg/min. Autopsy eight days later revealed neither evidence of incorrect surgical closure nor another cardiovascular malformation. We conclude that in rare cases, with probably low cardiac output and low peripheral resistance, the diastolic flow in the cerebral artery can become negative without underlying cardiovascular malformation, such as PDA. G. Jorch M.D. J. Pfefferkorn M.D. Universitfitskinderklinik 4400 Mfmster, West Germany

In a study ~ of cerebral and carotid arteries, we concluded that carotid flow was more sensitive in detecting PDA and permitted us to distinguish flow reversal resulting from PDA from that resulting from other hemodynamic abnormalities. If there is reversal in the cerebral artery, there also must be reversal in the carotid artery. However, the converse is not necessarily true. The contour of the arterial pulse waveform becomes damped as it moves distally in the circulatory system. Therefore, the waveform derived from the cerebral artery is significantly different from that in the carotid, and frequently the diastolic portion appears as a continuation of the downslope of the preceding systolic peak. In contrast, the diastolic portion of the carotid waveform is very distinct and permits early detection of PDA in the presence of a very small left-to-right shunt. This is manifested as late diastolic reversal. As the shunt magnitide increases, the reversal increases correspondingly, ultimately becoming pandiastolic. The indistinct cerebral artery diastolic waveform may explain the inability of Jorche and Pfefferkorn to detect a small PDA with this technique in four of their eight patients. We have studied the carotid diastolic waveform in two infants with septic shock, but found it to be distinctly different from that resulting from PDA. Diastolic reversal in these two infants appeared as an early diastolic reversal spike, after which the waveform approached zero from the negative side of the flow velocity curve, becoming positive in late diastole. Damping of the cerebral artery waveform may make it impossible to distinguish between reversal resulting from PDA and that from septic shock and other causes of impaired diastolic perfusion. IV. Dean Wilcox, M.D. Tim A. Carrigan, M.S.A.E. Peter A. Ahmann, M.D. Department of Pediatrics Emory University School of Medicine Don P. Giddens, Ph.D. School of Aerospace Engineering Georgia Institute of Technology Atlanta, GA

REFERENCES

REFERENCE

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dimensions of children's environments. J Pediatr Psychol 7:425 , 1982. Needleman HL, Gunnoe CE, Leviton A, Reed R, Peresie H, Maher C, Barrett P: Deficits in psychologic and classroom performance of children with elevated dentine lead levels. N Engl J Med 300:689, 1979.

Direction of flow with PDA

1. Wilcox WD, Carrigan TA, Dooley K J, Giddens DP, Dykes FD, Lazarra A, Ray JL, Ahmann PA: Range-gated pulsed Doppler ultrasonographic evaluation of carotid arterial blood flow in small preterm infants with patent ductus arteriosus. J PEDIATR 102:294, 1983. 2. Martin CG, Snider AR, Katz SM, Peabody JL, Brady JP: Abnormal cerebral blood flow patterns in preterm infants with a large patent ductus arteriosus. J PEDIATR 101:587, 1982.

Reply To the Editor: Jorehe and Pfefferkorn raise several pertinent points regarding the effect of patent ductus arteriosus on blood flow in the carotid and anterior cerebral arteries as determined by pulsed Doppler technique.

1. Wilcox WD, Carrigan TA, Dooley K J, Dykes FD, Lazzara A, Giddens DP: Range-gated pulsed Doppler ultrasonographic evaluation of carotid and anterior cerebral blood flow in small pre-term infants with patent ductus arteriosus (abstr). Pediatr Cardiol 3:355, 1982.

Human t3-endorphin level determination To the Editor: We read with interest the recent paper by Moss et al? describing a procedure for measuring/3-endorphin-like immunoreactivity (ELI) in raw (i.e., unextracted) plasma. The authors suggest that if a number of calculations are performed on the ELI values, the/3-endorphin (ED) level can be estimated. The New England Nuclear ED radioimmunoassay kit used by

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Editorial correspondence

The Journal of Pediatrics November 1983

Table. E L I and E D plasma values in two groups of infants

ELI (pg/mO

ED (pg/mO

Group 1 (_