Volume 167 Number 6
Letters
3. Broughton Pipkin F, Benjamin N, Macallan C. Placental transfer of a large angiotensin fragment in the guinea pig. AM] OBSTET GYNECOL 1977;128:904-6. 4. Loquet P, Broughton Pipkin F, Symonds EM, Rubin PC. Influence of rising maternal blood pressure with angiotensin II on utero-placental and feto-placental blood velocity indices in the human. Clin Sci 1990;78:95-100.
"Classic nonstress test" and "ambulatory stress test" in the assessment of umbilical cord compression
To the Editors: 10. Interpretation of fetal heart rate records 10.1. Four main factors should be taken into account: a) ...
b) maternal position c) the state of fetal activity d) ...
FICO News' The letter by Collins (Collins JH. First report: telemetry-assisted ambulatory nonstress test to evaluate umbilical cord compression. AM J OBSTET CVNECOL 1992; 166: 1020-1) addresses a subject that is within the scope of my research. Few papers discuss the influence of maternal position and activity on the results of fetal biophysical tests. However, I cannot understand the interpretation of the published cardiotocograms on which all the report assumptions are based. Indeed, it is suggested by the text that the top tracing supposedly represents a typical tracing of a fetus with umbilical cord entanglements obtained from an ambulatory mother, and the bottom tracing shows the effect of maternal supine position on the same fetus! Everyone who is familiar with the concept of fetal behavioral states 2 , 3 recognizes that the top tracing is (or at least simulates very well) a typical fetal heart rate (FHR) pattern D corresponding to behavioral state 4F, which is quite normal in term fetuses and is very often observed with the mother supine. The bottom tracing looks like a normal FHR pattern A or B, extremely frequent in normal, term fetuses whatever the mother's position and activity. Both tracings occur in normal fetuses, with or without cord entanglements, with the mother supine or without! I suggest that fetal behavioral states be checked in the published case by analyzing the FHR registration following the top and bottom tracings (if it exists). Fetal behavioral states are cyclical, and the top tracing can occur sometime after or before the bottom one and vice versa. It is just a question of prolonging the registration. I do think that without an answer to the aforementioned doubts this report cannot support at all any difference betwee.l a so-called "classic nonstress test" and "ambulatory stress test," namely in the case of the fetus with entanglements of the umbilical cord. A clarification should avoid possible future (wrong?) actions based on eventually misleading observations. JOlio Bernardes, MD Rua Augusto Lessa, 555-2° E, 4200 Porto, Portugal
1911
REFERENCES l. Rooth G, Huch A, Huch R. Guidelines for the use of fetal
monitoring. Int] Gynaecol Obstet 1987;25: 159. 2. De Vries HIP, Visser GHA, Prechtl HFR. The emergence of fetal behaviour. II. Quantitative aspects, Early Hum Dev 1985;12:95. 3. Woerden van EE. Fetal heart rate and movements: their relationship within behavioural states IF and 2F [Thesis]. Amesterdam: Free University, 1989. 169 p.
Reply
To the Editors: I appreciate the opportunity to respond to the comments by Bernardes. As he states, "few papers discuss the influence of maternal position and activity on the results of fetal biophysical tests." Telemetry science is an alternative means of studying these effects. This equipment has only recently been commercially available. As a private-practice obstetrician, I believe it imperative to explore new technology and report to my specialty colleagues observations believed to be different. It is necessary to stimulate interest and encourage others to confirm or dispute these observations. In a brief Letter to the Editors the reporting of two cases evaluated by ambulatory telemetry nonstress tests was not intended to be definitive, or change management actions, or mislead. The pictures published were an example of a broader observation covering 2 weeks. Continuous fetal monitoring, with ambulation and rest recorded at different times of the day on different days, are available for review. The segments chosen and numbered illustrated the change and difference between the supine state and ambulatory state within close time proximity. Behavioral states of activity and nonactivity as determined by patient diaries did not alter this difference. Although a specific ultrasonographic confirmation of state 4F cannot be offered to Bernardes, the observation does not change simply because sustained fetal heart rate elevation was recorded but only during ambulation and not at any time when the mother was supine. In addition, Bernardes fails to consider fetal hiccup behavior as an influence. Patient diaries included hiccup episodes, and these did not cause elevated fetal heart rate baselines. Van Woerden et al.,' referred to by Bernardes, did not ambulate patients or report on the delivery results or presence of placental and umbilical cord abnormalities that may have influenced data. I hope that researchers such as Bernardes would explore with me this new technology and conduct a prospective evaluation. A comparison with the classic nons tress test and biophysical profile should be done where specificity, sensitivity, positive predictive values, and negative predictive values are determined. Only then will it be clear whether or not the telemetry-assisted ambulatory nonstress test can be of benefit, especially in cases of cord compression. Jason H. Collins, MD 1344 Covington Highway, Slidell, LA 70460
REFERENCE l. van Woerden EE, van Geijn HP, Carson F]M, et al. Fetal
hiccups: characteristics and relation to fetal heart rate. Eur ] Obstet Gynecol Reprod Bioi 1989;30:209-16.
Letters
3. Broughton Pipkin F, Benjamin N, Macallan C. Placental transfer of a large angiotensin fragment in the guinea pig. AM] OBSTET GYNECOL 1977;128:904-6. 4. Loquet P, Broughton Pipkin F, Symonds EM, Rubin PC. Influence of rising maternal blood pressure with angiotensin II on utero-placental and feto-placental blood velocity indices in the human. Clin Sci 1990;78:95-100.
"Classic nonstress test" and "ambulatory stress test" in the assessment of umbilical cord compression
To the Editors: 10. Interpretation of fetal heart rate records 10.1. Four main factors should be taken into account: a) ...
b) maternal position c) the state of fetal activity d) ...
FICO News' The letter by Collins (Collins JH. First report: telemetry-assisted ambulatory nonstress test to evaluate umbilical cord compression. AM J OBSTET CVNECOL 1992; 166: 1020-1) addresses a subject that is within the scope of my research. Few papers discuss the influence of maternal position and activity on the results of fetal biophysical tests. However, I cannot understand the interpretation of the published cardiotocograms on which all the report assumptions are based. Indeed, it is suggested by the text that the top tracing supposedly represents a typical tracing of a fetus with umbilical cord entanglements obtained from an ambulatory mother, and the bottom tracing shows the effect of maternal supine position on the same fetus! Everyone who is familiar with the concept of fetal behavioral states 2 , 3 recognizes that the top tracing is (or at least simulates very well) a typical fetal heart rate (FHR) pattern D corresponding to behavioral state 4F, which is quite normal in term fetuses and is very often observed with the mother supine. The bottom tracing looks like a normal FHR pattern A or B, extremely frequent in normal, term fetuses whatever the mother's position and activity. Both tracings occur in normal fetuses, with or without cord entanglements, with the mother supine or without! I suggest that fetal behavioral states be checked in the published case by analyzing the FHR registration following the top and bottom tracings (if it exists). Fetal behavioral states are cyclical, and the top tracing can occur sometime after or before the bottom one and vice versa. It is just a question of prolonging the registration. I do think that without an answer to the aforementioned doubts this report cannot support at all any difference betwee.l a so-called "classic nonstress test" and "ambulatory stress test," namely in the case of the fetus with entanglements of the umbilical cord. A clarification should avoid possible future (wrong?) actions based on eventually misleading observations. JOlio Bernardes, MD Rua Augusto Lessa, 555-2° E, 4200 Porto, Portugal
1911
REFERENCES l. Rooth G, Huch A, Huch R. Guidelines for the use of fetal
monitoring. Int] Gynaecol Obstet 1987;25: 159. 2. De Vries HIP, Visser GHA, Prechtl HFR. The emergence of fetal behaviour. II. Quantitative aspects, Early Hum Dev 1985;12:95. 3. Woerden van EE. Fetal heart rate and movements: their relationship within behavioural states IF and 2F [Thesis]. Amesterdam: Free University, 1989. 169 p.
Reply
To the Editors: I appreciate the opportunity to respond to the comments by Bernardes. As he states, "few papers discuss the influence of maternal position and activity on the results of fetal biophysical tests." Telemetry science is an alternative means of studying these effects. This equipment has only recently been commercially available. As a private-practice obstetrician, I believe it imperative to explore new technology and report to my specialty colleagues observations believed to be different. It is necessary to stimulate interest and encourage others to confirm or dispute these observations. In a brief Letter to the Editors the reporting of two cases evaluated by ambulatory telemetry nonstress tests was not intended to be definitive, or change management actions, or mislead. The pictures published were an example of a broader observation covering 2 weeks. Continuous fetal monitoring, with ambulation and rest recorded at different times of the day on different days, are available for review. The segments chosen and numbered illustrated the change and difference between the supine state and ambulatory state within close time proximity. Behavioral states of activity and nonactivity as determined by patient diaries did not alter this difference. Although a specific ultrasonographic confirmation of state 4F cannot be offered to Bernardes, the observation does not change simply because sustained fetal heart rate elevation was recorded but only during ambulation and not at any time when the mother was supine. In addition, Bernardes fails to consider fetal hiccup behavior as an influence. Patient diaries included hiccup episodes, and these did not cause elevated fetal heart rate baselines. Van Woerden et al.,' referred to by Bernardes, did not ambulate patients or report on the delivery results or presence of placental and umbilical cord abnormalities that may have influenced data. I hope that researchers such as Bernardes would explore with me this new technology and conduct a prospective evaluation. A comparison with the classic nons tress test and biophysical profile should be done where specificity, sensitivity, positive predictive values, and negative predictive values are determined. Only then will it be clear whether or not the telemetry-assisted ambulatory nonstress test can be of benefit, especially in cases of cord compression. Jason H. Collins, MD 1344 Covington Highway, Slidell, LA 70460
REFERENCE l. van Woerden EE, van Geijn HP, Carson F]M, et al. Fetal
hiccups: characteristics and relation to fetal heart rate. Eur ] Obstet Gynecol Reprod Bioi 1989;30:209-16.
