- Email: [email protected]
Reply by Dr. Nyirjesy
Correspondence
\'olume s~ I\utnbf'r 4
patients, including the observation that cases of dPpressed infants occurred significantly more often in the block series. Such statistical comparisons are valid if the members of each group arc comparable and selected by some entirely random or "blind" method. But we are told nothing of how the "'control" group was picked. We arc• not told why 337 "controls" were chosen, almost live times the number of patients who received blocks, or why only 237 control patients were mcd for one comparison (Table IV). The median duration of first stage labor was shown to be longer in the patients who werf' given blocks, but the significance of this is questionable since the groups are not known to be alikf' in other respects. For example, although 'l:i patients were "assigned" paracervical block, only 68 actually received them. It has been our ··xpericncc that progress in labor in some patients is too rapid to allow the blocks to be done. 1f some of the 27 patients eliminated fell into this category, the effect this would have upon the median duration of first stage labor in the block group versus the no-block group is obvious. If there is not random selection of patients for blocks, then• would naturally be a tendency for a concentration of them in the group with longer labor, since there is then obviously a great<'r opportunity for accomplishment of the block. In other words, did some patients receive blocks lwcause thC' labor was relatively long? On the whole analgesia was administered earlier in the block series (Table IV). Could this have had an effect in prolonging the labor? It should also be pointed out in this connection that tlw longer median duration of labor in the block group suggests a possible concentration of difficult labor in this category, with consequent possibilities for adverse effects on the condition ••f infants at birth as manifested by the Apgar ·"·orcs. One infant death in the report was attributed to the· procedure. There was clearly a close chronologie relationship between administration of the block and disappearance of the fetal heart tones. The authors point out, however, in the body of the paper, that this occurred in a patient in premature labor with severe toxemia (blood pressure of 160/100, edema, albuminuria~ and BUN of 40 mgm. per cent). The stillborn infant weighed 2,000 grams and was delivered by low forceps extraction after a failed attempt at cxtt·action with a vacuum extractor. Tlwy also noted transient fetal bradycardia after administration of the block in 22 per cent.
555
Other authors have also noted this phenomenon, though less frequently. It obviously cannot be ignored. However, with two possible exceptions, the two infant deaths reported upon by Freeman and associates, no significant effects on the infant have been noted at birth. If, as Nyirjesy suggests (and as Page did before him) , this fetal heart rate depression is caused by a direct effect of absorbed local anesthetic on the fetal myocardium, it should be urged that smaller amounts be used for the blocks. Five to 6 cubic centimeters at each injection site has been demonstrated to be as effective as larger volumes. Finally, the comparatively poor results regarding pain relief (compared with numerous other published reports) obtained by the authors suggest some fault in technique. This may have to do with the depth of the injection which is described as "limited to the immediate submucosal area." Others have found the optimum depth of injection to be approximately 1.5 em. D. W. Freeman. M.D. St. Louis Park Medical Center 4959 Excelsior Blvd. Minneapolis, Minnesota 55416
Reply by Dr. Nyirjesy
To the Editors: I must take strong issue with Dr. Freeman's statement in reference to our summary of complications reported by other authors. Facts reported in the literature can be interpreted in different manners by various readers. Paracervical block can theoretically produce complications, either by the mechanical gesture of introduction of a needle through the vagina into the parametrium (such as infection and hematoma), by the agent itself (neuritis, as in the case referred to by Dr. Freeman), or sytemic effects (such as the case of peripheral vascular collapse and convulsions). In my interpretation, either type of untoward effect has to be classified as a complication of paracervical block. We are aware of the fact that Spanos and Steele attributed their case of sacral neuritis to pudendal block, but since the combined technique was used this could have been caused by either of the t\\'O techniques. Concerning the selection of our patients for the study, the method was biind-random. Specifically, each time a patient was found to he eligible for the study. an envelope was opened (these were arranged in a random series by a
556
Correspondence
.\nl .
statistician), and the instructions "para cervical block" or "no paracervical block" were followed in all cases \Vith the exception of those specified in our article. Had we not discontinued our study prematurely from fear of more complications, the number of the patients in the study and control groups would have been similar. Only 23 7 patients were listed as control patients in Table IV since only they (more precisely 246 less 9 '·unknown"), received analgesia. :\s to Dr. Freeman's question whether only tlw paracervical block could have produced thP lower Apgar scores, the answer is obviously no. However, it should be re-emphasized that there was a high statistical difference (p 0.001) between the Apgar scores of the newborn infants in the two groups, and that there was no such difft'rence in the comparison of other factors, such as analgesia, anesthesia, method of delivery, etc. Therefore, we had to conclude that paracervical block was responsible for depressed newborn infants in this study. Regarding our "comparatively poor results concerning pain relief," it should be noted that the method we used for evaluation of this factor \\·as entirely different from that of Dr. Fn•pman
<
\\·hu ba:scJ his opinion upon the physiCian's
O\vn
observations. \Ve attempted to eliminate the physician's bias and used, therefore, two methods \\·ith ('ach patient. At {irst, we told the patient prior to the administration of the block that the pain W;:JS 1on per Cf'nt. Following t]1f' block, W<' asked her to estimate the intensity of the residual pain in per cent, as compared to the preblock I 00 prr cent pain. From this we calculated thr )l('r cent of pain relief. A second method was a questionnaire which was completed on the first postpartum day by the patient. She classified tlw degre(' of pain relief as complete, considerable, slight, or non('. We felt, that although obstetrical pain cannot be measured accurately, these two methods arc more objective than the direct observation which could be colored by the physician's bias. The difference in the method of evaluation, and not a faulty technique, is the most likely cause for the different results with pain relief. The other questions, raised by Dr. Freeman have been answered in previous letters to thc editors. !. Nyirjcsr. /,CDH. MC. [OSX Station Hospital, Naples Naval Support Actiz,itiP.< Navy 510, Box 19 FPO, New York, New York
.I
Oh:.t, 0.: ( ,\II• 1 lunt' 1-;_ l('ld
Instrument delivery
To the Editors: In rhe arnc1e, "Instrument Clcllvcry on till~ fetal heart rate" (AM. J. 0BST. & GYNEC. 87: 529, 1963), Dr. J. V. Kelly has arrived at several conclusions that I feel deserve comment. Tht· following arc quotations from his artie!<- with my rebuttal. "The slowing of the heart rate when forceps were applied seemed to be a sign of impending peril for when bradycardia occurred at this specific phase of the delivery there was greater than a 50 per cent chance that the baby would I)(' depressed at birth." The author failed to compare his findings "ith a control group, that is, of a surgical delin·ry
and a spontaneous delivery. \Vc 1 have shown that bradycardia is more closely related to ktal head station than to forceps application and traction. The fetal heart rate is depressed in a similar fashion in both forceps and spontancom clclivcri(•s (Table III). H'l'here is some suggestion that there x~ ~~
greater chance for asphyxia at birth in infants whose heart rate displays a tardy return to normal after traction." Again, 1 depending upon the position of the head in the birth cana1, the fetal heart rate
never returns to a resting level until completl' delivery of the infant is accomplished. This phenomenon occurs in both forceps and spontaneous deliveries and is not related to forceps traction but to fetal position, in normal dPiiverics. \Vp could not demonstrate a lowering of /\pgar score with delivery fetal heart depression. "Forceps deliveries in which individual pulls
of 50 or more pounds were required were
associated with a high rate of depressed infants at birth." The author measured only peak force. He failed to measure accelerating force to reach this peak force, or decelerating force and duration pull. We were unable to correlate this peak force with fetal depression and/ or asphyxia. however, total delivery force 1 could possibly lw incriminated. I am railing this subject to the attention uf your readers because I bclieve that the lack of a control group in Dr. Kelly's study prevents him from making valid conclusions concerning the fetal heart response to the forces cxPrtcd h) ub.stctrical forceps.
\'olume s~ I\utnbf'r 4
patients, including the observation that cases of dPpressed infants occurred significantly more often in the block series. Such statistical comparisons are valid if the members of each group arc comparable and selected by some entirely random or "blind" method. But we are told nothing of how the "'control" group was picked. We arc• not told why 337 "controls" were chosen, almost live times the number of patients who received blocks, or why only 237 control patients were mcd for one comparison (Table IV). The median duration of first stage labor was shown to be longer in the patients who werf' given blocks, but the significance of this is questionable since the groups are not known to be alikf' in other respects. For example, although 'l:i patients were "assigned" paracervical block, only 68 actually received them. It has been our ··xpericncc that progress in labor in some patients is too rapid to allow the blocks to be done. 1f some of the 27 patients eliminated fell into this category, the effect this would have upon the median duration of first stage labor in the block group versus the no-block group is obvious. If there is not random selection of patients for blocks, then• would naturally be a tendency for a concentration of them in the group with longer labor, since there is then obviously a great<'r opportunity for accomplishment of the block. In other words, did some patients receive blocks lwcause thC' labor was relatively long? On the whole analgesia was administered earlier in the block series (Table IV). Could this have had an effect in prolonging the labor? It should also be pointed out in this connection that tlw longer median duration of labor in the block group suggests a possible concentration of difficult labor in this category, with consequent possibilities for adverse effects on the condition ••f infants at birth as manifested by the Apgar ·"·orcs. One infant death in the report was attributed to the· procedure. There was clearly a close chronologie relationship between administration of the block and disappearance of the fetal heart tones. The authors point out, however, in the body of the paper, that this occurred in a patient in premature labor with severe toxemia (blood pressure of 160/100, edema, albuminuria~ and BUN of 40 mgm. per cent). The stillborn infant weighed 2,000 grams and was delivered by low forceps extraction after a failed attempt at cxtt·action with a vacuum extractor. Tlwy also noted transient fetal bradycardia after administration of the block in 22 per cent.
555
Other authors have also noted this phenomenon, though less frequently. It obviously cannot be ignored. However, with two possible exceptions, the two infant deaths reported upon by Freeman and associates, no significant effects on the infant have been noted at birth. If, as Nyirjesy suggests (and as Page did before him) , this fetal heart rate depression is caused by a direct effect of absorbed local anesthetic on the fetal myocardium, it should be urged that smaller amounts be used for the blocks. Five to 6 cubic centimeters at each injection site has been demonstrated to be as effective as larger volumes. Finally, the comparatively poor results regarding pain relief (compared with numerous other published reports) obtained by the authors suggest some fault in technique. This may have to do with the depth of the injection which is described as "limited to the immediate submucosal area." Others have found the optimum depth of injection to be approximately 1.5 em. D. W. Freeman. M.D. St. Louis Park Medical Center 4959 Excelsior Blvd. Minneapolis, Minnesota 55416
Reply by Dr. Nyirjesy
To the Editors: I must take strong issue with Dr. Freeman's statement in reference to our summary of complications reported by other authors. Facts reported in the literature can be interpreted in different manners by various readers. Paracervical block can theoretically produce complications, either by the mechanical gesture of introduction of a needle through the vagina into the parametrium (such as infection and hematoma), by the agent itself (neuritis, as in the case referred to by Dr. Freeman), or sytemic effects (such as the case of peripheral vascular collapse and convulsions). In my interpretation, either type of untoward effect has to be classified as a complication of paracervical block. We are aware of the fact that Spanos and Steele attributed their case of sacral neuritis to pudendal block, but since the combined technique was used this could have been caused by either of the t\\'O techniques. Concerning the selection of our patients for the study, the method was biind-random. Specifically, each time a patient was found to he eligible for the study. an envelope was opened (these were arranged in a random series by a
556
Correspondence
.\nl .
statistician), and the instructions "para cervical block" or "no paracervical block" were followed in all cases \Vith the exception of those specified in our article. Had we not discontinued our study prematurely from fear of more complications, the number of the patients in the study and control groups would have been similar. Only 23 7 patients were listed as control patients in Table IV since only they (more precisely 246 less 9 '·unknown"), received analgesia. :\s to Dr. Freeman's question whether only tlw paracervical block could have produced thP lower Apgar scores, the answer is obviously no. However, it should be re-emphasized that there was a high statistical difference (p 0.001) between the Apgar scores of the newborn infants in the two groups, and that there was no such difft'rence in the comparison of other factors, such as analgesia, anesthesia, method of delivery, etc. Therefore, we had to conclude that paracervical block was responsible for depressed newborn infants in this study. Regarding our "comparatively poor results concerning pain relief," it should be noted that the method we used for evaluation of this factor \\·as entirely different from that of Dr. Fn•pman
<
\\·hu ba:scJ his opinion upon the physiCian's
O\vn
observations. \Ve attempted to eliminate the physician's bias and used, therefore, two methods \\·ith ('ach patient. At {irst, we told the patient prior to the administration of the block that the pain W;:JS 1on per Cf'nt. Following t]1f' block, W<' asked her to estimate the intensity of the residual pain in per cent, as compared to the preblock I 00 prr cent pain. From this we calculated thr )l('r cent of pain relief. A second method was a questionnaire which was completed on the first postpartum day by the patient. She classified tlw degre(' of pain relief as complete, considerable, slight, or non('. We felt, that although obstetrical pain cannot be measured accurately, these two methods arc more objective than the direct observation which could be colored by the physician's bias. The difference in the method of evaluation, and not a faulty technique, is the most likely cause for the different results with pain relief. The other questions, raised by Dr. Freeman have been answered in previous letters to thc editors. !. Nyirjcsr. /,CDH. MC. [OSX Station Hospital, Naples Naval Support Actiz,itiP.< Navy 510, Box 19 FPO, New York, New York
.I
Oh:.t, 0.: ( ,\II• 1 lunt' 1-;_ l('ld
Instrument delivery
To the Editors: In rhe arnc1e, "Instrument Clcllvcry on till~ fetal heart rate" (AM. J. 0BST. & GYNEC. 87: 529, 1963), Dr. J. V. Kelly has arrived at several conclusions that I feel deserve comment. Tht· following arc quotations from his artie!<- with my rebuttal. "The slowing of the heart rate when forceps were applied seemed to be a sign of impending peril for when bradycardia occurred at this specific phase of the delivery there was greater than a 50 per cent chance that the baby would I)(' depressed at birth." The author failed to compare his findings "ith a control group, that is, of a surgical delin·ry
and a spontaneous delivery. \Vc 1 have shown that bradycardia is more closely related to ktal head station than to forceps application and traction. The fetal heart rate is depressed in a similar fashion in both forceps and spontancom clclivcri(•s (Table III). H'l'here is some suggestion that there x~ ~~
greater chance for asphyxia at birth in infants whose heart rate displays a tardy return to normal after traction." Again, 1 depending upon the position of the head in the birth cana1, the fetal heart rate
never returns to a resting level until completl' delivery of the infant is accomplished. This phenomenon occurs in both forceps and spontaneous deliveries and is not related to forceps traction but to fetal position, in normal dPiiverics. \Vp could not demonstrate a lowering of /\pgar score with delivery fetal heart depression. "Forceps deliveries in which individual pulls
of 50 or more pounds were required were
associated with a high rate of depressed infants at birth." The author measured only peak force. He failed to measure accelerating force to reach this peak force, or decelerating force and duration pull. We were unable to correlate this peak force with fetal depression and/ or asphyxia. however, total delivery force 1 could possibly lw incriminated. I am railing this subject to the attention uf your readers because I bclieve that the lack of a control group in Dr. Kelly's study prevents him from making valid conclusions concerning the fetal heart response to the forces cxPrtcd h) ub.stctrical forceps.