CORRESPONDENCE
Severe variable decelerations in fetal heart rate To the editor: In his letter "Failure of continuous fetal heart monitoring to indicate severe fetal distress" (Can Med Assoc J 114: 672, 1976) Dr. P. T. Hewlett stated that "early decelerations in the fetal heart tracing may occur with severe intrauterine fetal hypoxia". This finding is not consistent with my personal experiences, spanning almost 2 decades, or with the pertinent medical literature when the fetal heart rate pattern of early deceleration has been identified correctly. Since it has been, and still is, our teaching that early deceleration patterns are not associated with fetal depression or asphyxia, it is important to determine if the fetal heart rate patterns Dr. Hewlett is calling "early decelerations" truly meet our criteria for such a label. If not, they should be called something else; if they do, we will need to re-examine our past and current teaching. EDWARD H. HON, MD Dore professor of obstetrics and gynecology Chief, perinatal research School of medicine University of Southern California Los Angeles, CA
To the editor: A photograph of the tracing from my case was sent to Dr. Hon. His reply included the following: "After glancing quickly at the form tracings, it was my conclusion that we were not dealing with a relatively benign foetal heart rate change but rather with a readily identifiable severe variable deceleration which we believe is caused by umbilical cord compression. Using the classification of CaldeyroBarcia,1 the time between the peak of the uterine contraction and the lowest point of the fetal heart rate deceleraContributions to the Correspondence section are welcomed and if considered suitable will be published as space permits. They should be typewritten double spaced and, except for case reports, should not exceed 1½ pages in length.
tion is the critical factor in deciding between type 1 and type 2 dips. In my tracing the time lag was less than 18 seconds and the classification was therefore type 1 dips or early decelerations. Because the later pattern showed some irregularity in the shape of the fetal heart rate waveform, the dips should be classified as variable decelerations. One of the many problems associated with continuous fetal heart rate monitoring is that of the classification of the tracings obtained. Dr. Hon2 was one of the pioneers of fetal heart rate monitoring and if he states that under his classification the patterns in this case are those of "readily identifiable severe variable deceleration", then they are. Those using other methods of classification might have found identification and management in this case somewhat less clearly defined. Two cases of early decelerations in association with intrauterine death were reported by Wood and colleagues3 from Australia in 1969, and in Toronto one similar case has been reported (D. Gare: personal communication, 1976). Sudden intrauterine death with no preceding abnormality in fetal heart rate with continuous monitoring has also recently been reported.4 The association of early decelerations in fetal heart rate with an inability to obtain fetal scalp blood is of sinister prognostic significance. P.T. HEWLETT, MB, FRCS(C] Women's College Hospital Toronto, ON References 1. CALDEYRO-BARCIA R. CASACUBERTA C, BusTos
R, et al: Correlation of intrapartum changes in fetal heart rate with fetal blood oxygen and acid base balance, in Diagnosis and Treatment of Fetal Disorders, ADAMsoNs K (ed), New York, Springer, 1968, pp 205-25
2. HON EH, QUILLIGAN EJ: Electronic evaluation of fetal heart rate. Clin Obstet Gynecol 2: 145. 1968 3. Wooo C, NEWMAN W, LUMLEY J, et al: Classification of fetal heart rate in relation to fetal scalp blood measurements and Apgar
score. Am J Obstet Gynecol 105: 947, 1969
4. HAYA5HI R, Fox M: Sudden intra-partum fetal death during continuous fetal heart
rate monitoring. Am J Obstet Gynecol 122: 786, 1975
African cattle tick infesting a Canadian To the editor: Following her recent return from Africa a 49-year-old Canadian woman found a tick embedded in the skin of her shoulder. The parasite was subsequently identified at the parasitology laboratory of the Ontario Ministry of Health in Toronto as a female Rhipicephalus puichellus (Fig. 1). Subsequent enquiry revealed that the patient had visited Kenya and Tanzania, and while there was in close contact with cattle. ..
FIG 1 Female Rhipicephalus puichellus. This species is a parasite of cattle, antelopes dogs and other mammals in East Africa and seems fairly resistant to cold 1 While it is probably doubtful that this tick could become permanently established in Canada, it is not inconceivable that it could establish itself temporarily during the summer. As with a previous report,2 this case illustrates the ease with which parasites and other organisms can be imported into countries where they are not usually found, as a result of increasingly rapid air travel, and re-em-
CMA JOURNAL/SEPTEMBER 18, 1976/VOL. 115 491
Severe variable decelerations in fetal heart rate To the editor: In his letter "Failure of continuous fetal heart monitoring to indicate severe fetal distress" (Can Med Assoc J 114: 672, 1976) Dr. P. T. Hewlett stated that "early decelerations in the fetal heart tracing may occur with severe intrauterine fetal hypoxia". This finding is not consistent with my personal experiences, spanning almost 2 decades, or with the pertinent medical literature when the fetal heart rate pattern of early deceleration has been identified correctly. Since it has been, and still is, our teaching that early deceleration patterns are not associated with fetal depression or asphyxia, it is important to determine if the fetal heart rate patterns Dr. Hewlett is calling "early decelerations" truly meet our criteria for such a label. If not, they should be called something else; if they do, we will need to re-examine our past and current teaching. EDWARD H. HON, MD Dore professor of obstetrics and gynecology Chief, perinatal research School of medicine University of Southern California Los Angeles, CA
To the editor: A photograph of the tracing from my case was sent to Dr. Hon. His reply included the following: "After glancing quickly at the form tracings, it was my conclusion that we were not dealing with a relatively benign foetal heart rate change but rather with a readily identifiable severe variable deceleration which we believe is caused by umbilical cord compression. Using the classification of CaldeyroBarcia,1 the time between the peak of the uterine contraction and the lowest point of the fetal heart rate deceleraContributions to the Correspondence section are welcomed and if considered suitable will be published as space permits. They should be typewritten double spaced and, except for case reports, should not exceed 1½ pages in length.
tion is the critical factor in deciding between type 1 and type 2 dips. In my tracing the time lag was less than 18 seconds and the classification was therefore type 1 dips or early decelerations. Because the later pattern showed some irregularity in the shape of the fetal heart rate waveform, the dips should be classified as variable decelerations. One of the many problems associated with continuous fetal heart rate monitoring is that of the classification of the tracings obtained. Dr. Hon2 was one of the pioneers of fetal heart rate monitoring and if he states that under his classification the patterns in this case are those of "readily identifiable severe variable deceleration", then they are. Those using other methods of classification might have found identification and management in this case somewhat less clearly defined. Two cases of early decelerations in association with intrauterine death were reported by Wood and colleagues3 from Australia in 1969, and in Toronto one similar case has been reported (D. Gare: personal communication, 1976). Sudden intrauterine death with no preceding abnormality in fetal heart rate with continuous monitoring has also recently been reported.4 The association of early decelerations in fetal heart rate with an inability to obtain fetal scalp blood is of sinister prognostic significance. P.T. HEWLETT, MB, FRCS(C] Women's College Hospital Toronto, ON References 1. CALDEYRO-BARCIA R. CASACUBERTA C, BusTos
R, et al: Correlation of intrapartum changes in fetal heart rate with fetal blood oxygen and acid base balance, in Diagnosis and Treatment of Fetal Disorders, ADAMsoNs K (ed), New York, Springer, 1968, pp 205-25
2. HON EH, QUILLIGAN EJ: Electronic evaluation of fetal heart rate. Clin Obstet Gynecol 2: 145. 1968 3. Wooo C, NEWMAN W, LUMLEY J, et al: Classification of fetal heart rate in relation to fetal scalp blood measurements and Apgar
score. Am J Obstet Gynecol 105: 947, 1969
4. HAYA5HI R, Fox M: Sudden intra-partum fetal death during continuous fetal heart
rate monitoring. Am J Obstet Gynecol 122: 786, 1975
African cattle tick infesting a Canadian To the editor: Following her recent return from Africa a 49-year-old Canadian woman found a tick embedded in the skin of her shoulder. The parasite was subsequently identified at the parasitology laboratory of the Ontario Ministry of Health in Toronto as a female Rhipicephalus puichellus (Fig. 1). Subsequent enquiry revealed that the patient had visited Kenya and Tanzania, and while there was in close contact with cattle. ..
FIG 1 Female Rhipicephalus puichellus. This species is a parasite of cattle, antelopes dogs and other mammals in East Africa and seems fairly resistant to cold 1 While it is probably doubtful that this tick could become permanently established in Canada, it is not inconceivable that it could establish itself temporarily during the summer. As with a previous report,2 this case illustrates the ease with which parasites and other organisms can be imported into countries where they are not usually found, as a result of increasingly rapid air travel, and re-em-
CMA JOURNAL/SEPTEMBER 18, 1976/VOL. 115 491
