Reply to: Intrapartum fetal heart rate assessment: Which method is superior?

Abstract

Reply to the Editor:The controversy of continuous electronic fetal heart rate (FHR) monitoring versus intermittent auscultation continues. The purpose of our recent article was to compare the two methods in detecting (not decreasing) fetal acidemia at birth. Most of the points raised have to do with the ability of electronic FHR monitoring to decrease rather than detect fetal acidemia.The first point that needs to be clarified is that the frequencies of moderate degrees of acidemia (pH <7.15 or < 7.10) between the two groups were not statistically significant in our randomized trial (reference 1 of Sandmire and DeMott's letter). A decrease in the number of newborns with acidemia should be expected only if there is correct interpretation and timely intervention in the presence of nonreassuring FHR patterns. In our randomized trial the failure of the electronic FHR monitoring group to achieve fewer infants with moderate degrees of acidemia may be related to the specific interventional strategies used in the study or inaction when the FHR was nonreassuring. As we have indicated in our randomized trial, delayed or absent intervention was more frequent in the electronic FHR monitoring group (23/746 or 3% vs 9/682 or 1.3%, odds ratio 2.34, 95% confidence interval 1.07 to 5.08).The second point is that the frequency of very advanced acidemia (i.e., cord arterial pH <6.90) was less in the electronic FHR monitoring group (0.14% vs 0.44%), although this difference was not statistically significant. Objectively, the most severe degree of acidemia is the one that results in intrapartum fetal death. In our randomized trial there were two intrapartum fetal deaths in the intermittent auscultation group and none in the electronic FHR monitoring group.A third point is that two metaanalyses1Vintzileos AM Nochimson DJ Guzman ER Knuppel RA Lake M Schifrin BS. Intrapartum electronic fetal heart rate monitoring versus intermittent auscultation: a meta-analysis.Obstet Gynecol. 1995; 85: 149-155Crossref PubMed Scopus (184) Google Scholar, 2Thacker SB Stroup DF Peterson HB. Efficacy and safety of intrapartum electronic fetal monitoring: an update.Obstet Gynecol. 1995; 86: 613-620PubMed Google Scholar have shown that the use of continuous electronic FHR monitoring is associated with a lower frequency of 1-minute Apgar scores <4 (odds ratio 0.82, 95% confidence interval 0.65 to 0.98), fewer neonatal seizures (odds ratio 0.50, 95% confidence interval 0.30 to 0.82), less perinatal mortality from fetal hypoxia (odds ratio 0.41, 95% confidence interval 0.17 to 0.98), less overall perinatal mortality for non - United States studies (odds ratio 0.21, 95% confidence interval 0.12 to 0.29), and a trend for less overall perinatal mortality (odds ratio 0.76, 95% confidence interval 0.04 to 1.39).Last, it is not logical to accept that the two methods are equivalent when one of them (electronic FHR monitoring) can be virtually carried out in all patients, whereas the other (intermittent auscultation) can be carried out successfully in only 3.5% of the patients.3Morrison JC Chez BF Davis ID et al.Intrapartum fetal heart rate assessment monitoring by auscultation or electronic means.AM J OBSTET GYNECOL. 1993; 168: 63-66Abstract Full Text PDF PubMed Scopus (34) Google Scholar In our view, the available evidence clearly indicates that intermittent auscultation is not equivalent to continuous electronic FHR monitoring in detecting fetal compromise.6/8/71592 Reply to the Editor:The controversy of continuous electronic fetal heart rate (FHR) monitoring versus intermittent auscultation continues. The purpose of our recent article was to compare the two methods in detecting (not decreasing) fetal acidemia at birth. Most of the points raised have to do with the ability of electronic FHR monitoring to decrease rather than detect fetal acidemia.The first point that needs to be clarified is that the frequencies of moderate degrees of acidemia (pH <7.15 or < 7.10) between the two groups were not statistically significant in our randomized trial (reference 1 of Sandmire and DeMott's letter). A decrease in the number of newborns with acidemia should be expected only if there is correct interpretation and timely intervention in the presence of nonreassuring FHR patterns. In our randomized trial the failure of the electronic FHR monitoring group to achieve fewer infants with moderate degrees of acidemia may be related to the specific interventional strategies used in the study or inaction when the FHR was nonreassuring. As we have indicated in our randomized trial, delayed or absent intervention was more frequent in the electronic FHR monitoring group (23/746 or 3% vs 9/682 or 1.3%, odds ratio 2.34, 95% confidence interval 1.07 to 5.08).The second point is that the frequency of very advanced acidemia (i.e., cord arterial pH <6.90) was less in the electronic FHR monitoring group (0.14% vs 0.44%), although this difference was not statistically significant. Objectively, the most severe degree of acidemia is the one that results in intrapartum fetal death. In our randomized trial there were two intrapartum fetal deaths in the intermittent auscultation group and none in the electronic FHR monitoring group.A third point is that two metaanalyses1Vintzileos AM Nochimson DJ Guzman ER Knuppel RA Lake M Schifrin BS. Intrapartum electronic fetal heart rate monitoring versus intermittent auscultation: a meta-analysis.Obstet Gynecol. 1995; 85: 149-155Crossref PubMed Scopus (184) Google Scholar, 2Thacker SB Stroup DF Peterson HB. Efficacy and safety of intrapartum electronic fetal monitoring: an update.Obstet Gynecol. 1995; 86: 613-620PubMed Google Scholar have shown that the use of continuous electronic FHR monitoring is associated with a lower frequency of 1-minute Apgar scores <4 (odds ratio 0.82, 95% confidence interval 0.65 to 0.98), fewer neonatal seizures (odds ratio 0.50, 95% confidence interval 0.30 to 0.82), less perinatal mortality from fetal hypoxia (odds ratio 0.41, 95% confidence interval 0.17 to 0.98), less overall perinatal mortality for non - United States studies (odds ratio 0.21, 95% confidence interval 0.12 to 0.29), and a trend for less overall perinatal mortality (odds ratio 0.76, 95% confidence interval 0.04 to 1.39).Last, it is not logical to accept that the two methods are equivalent when one of them (electronic FHR monitoring) can be virtually carried out in all patients, whereas the other (intermittent auscultation) can be carried out successfully in only 3.5% of the patients.3Morrison JC Chez BF Davis ID et al.Intrapartum fetal heart rate assessment monitoring by auscultation or electronic means.AM J OBSTET GYNECOL. 1993; 168: 63-66Abstract Full Text PDF PubMed Scopus (34) Google Scholar In our view, the available evidence clearly indicates that intermittent auscultation is not equivalent to continuous electronic FHR monitoring in detecting fetal compromise. The controversy of continuous electronic fetal heart rate (FHR) monitoring versus intermittent auscultation continues. The purpose of our recent article was to compare the two methods in detecting (not decreasing) fetal acidemia at birth. Most of the points raised have to do with the ability of electronic FHR monitoring to decrease rather than detect fetal acidemia. The first point that needs to be clarified is that the frequencies of moderate degrees of acidemia (pH <7.15 or < 7.10) between the two groups were not statistically significant in our randomized trial (reference 1 of Sandmire and DeMott's letter). A decrease in the number of newborns with acidemia should be expected only if there is correct interpretation and timely intervention in the presence of nonreassuring FHR patterns. In our randomized trial the failure of the electronic FHR monitoring group to achieve fewer infants with moderate degrees of acidemia may be related to the specific interventional strategies used in the study or inaction when the FHR was nonreassuring. As we have indicated in our randomized trial, delayed or absent intervention was more frequent in the electronic FHR monitoring group (23/746 or 3% vs 9/682 or 1.3%, odds ratio 2.34, 95% confidence interval 1.07 to 5.08). The second point is that the frequency of very advanced acidemia (i.e., cord arterial pH <6.90) was less in the electronic FHR monitoring group (0.14% vs 0.44%), although this difference was not statistically significant. Objectively, the most severe degree of acidemia is the one that results in intrapartum fetal death. In our randomized trial there were two intrapartum fetal deaths in the intermittent auscultation group and none in the electronic FHR monitoring group. A third point is that two metaanalyses1Vintzileos AM Nochimson DJ Guzman ER Knuppel RA Lake M Schifrin BS. Intrapartum electronic fetal heart rate monitoring versus intermittent auscultation: a meta-analysis.Obstet Gynecol. 1995; 85: 149-155Crossref PubMed Scopus (184) Google Scholar, 2Thacker SB Stroup DF Peterson HB. Efficacy and safety of intrapartum electronic fetal monitoring: an update.Obstet Gynecol. 1995; 86: 613-620PubMed Google Scholar have shown that the use of continuous electronic FHR monitoring is associated with a lower frequency of 1-minute Apgar scores <4 (odds ratio 0.82, 95% confidence interval 0.65 to 0.98), fewer neonatal seizures (odds ratio 0.50, 95% confidence interval 0.30 to 0.82), less perinatal mortality from fetal hypoxia (odds ratio 0.41, 95% confidence interval 0.17 to 0.98), less overall perinatal mortality for non - United States studies (odds ratio 0.21, 95% confidence interval 0.12 to 0.29), and a trend for less overall perinatal mortality (odds ratio 0.76, 95% confidence interval 0.04 to 1.39). Last, it is not logical to accept that the two methods are equivalent when one of them (electronic FHR monitoring) can be virtually carried out in all patients, whereas the other (intermittent auscultation) can be carried out successfully in only 3.5% of the patients.3Morrison JC Chez BF Davis ID et al.Intrapartum fetal heart rate assessment monitoring by auscultation or electronic means.AM J OBSTET GYNECOL. 1993; 168: 63-66Abstract Full Text PDF PubMed Scopus (34) Google Scholar In our view, the available evidence clearly indicates that intermittent auscultation is not equivalent to continuous electronic FHR monitoring in detecting fetal compromise. 6/8/71592