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Lactate infusions: The role of baseline anxiety and autonomic measures
Psychiatry
263
Research. 22, 263-264
Elsevier
Letter Lactate Infusions: The Role of Baseline Anxiety and Autonomic Measures To the Editors:
We read with interest the article by Cowley et al. (1987) on lactate infusions and the role of baseline anxiety. They report that patients who had a typical panic attack with lactate had higher baseline anxiety symptom ratings, even though these did not fully account for differences in response to lactate. However, heart rate and blood pressure did not significantly differ between lactate responders and nonresponders. We have infused panic disorder patients and controls using sodium lactate, isoproterenol, and placebo in a double-blind randomized design. We found that preinfusion anxiety was significantly higher in those panic disorder patients and controls who panicked during lactate infusions compared to those who did not (Yeregani et al., in press a, in press b). The symptoms “afraid of going crazy” and “feeling unsteady” appeared to be the best predictors of a subsequent panic attack. There was no significant difference in the preinfusion heart rates of control panickers compared to nonpanickers (Yeragani et al., in press a). Although patients had a significant increase in heart rate just before infusions, there was no significant difference in preinfusion heart rates between panickers and nonpanickers for first infusion in our multiple infusion study (Yeragani et al., 1987h). We have also found no significant difference between the preinfusion heart rates of patients who panicked during placebo infusions and those who did not (Yeragani et al., 1987a). We have now compared baseline and preinfusion blood pressures between patients and controls and also between patient panickers and nonpanickers. Fifty-nine patients (35 females and 24 males) and 25 controls (9 females and I6 males) included in this study had baseline and preinfusion blood
0165-1781/87/$03.50
pressure data for all three infusions. All patients met Research Diagnostic Criteria (RDC) (Spitzer et al., 1978) for panic disorder. The subject selection and the infusion procedures have been previously described in detail (Rainey et al., 1984). Baseline blood pressures were recorded using the standard cuff technique and were done on the day of the patient’s initial psychiatric evaluation. Patients also knew that they would not receive an infusion at this time. Preinfusion blood pressures were recorded at 0 minutes using a Dinamap Vital Signs Monitor (Critikon, Tampa, FL) before the infusions were begun. A two-tailed t test did not reveal a significant difference in age between patients and controls (patients: 33.5 f 9.3; controls: 29.8 + 6.8; t = I .69, @= 82, NS). A two-way analysis of variance (ANOVA) (Table I) revealed that patients had significantly higher baseline and preinfusion systolic blood pressures for the three infusions (F = 9.1, df= I/81, p < 0.01). There were no other significant effects. The patients also had significantly higher diastolic pressures (F = 7.7, Gf = I /Sl, p < 0.01). There was also an overall significant decrease in diastolic blood pressure from baseline to the third infusion (F= 12.5, u”= 3/243,p < 0.01). There was no significant interaction effect. Fifty-one of 59 patients panicked during lactate, 42 of 59 during isoproterenol, and 7 of 52 during placebo infusions. Two-tailed t tests revealed no significant differences in the preinfusion systolic or diastolic blood pressures between patients who panicked and those who did not, either for first, second, or third infusions (Table I), or lactate (panickers: 124 + l5/72 + IO; nonpanickers: 125 + 20/73 + l4), isoproterenol (panickers: 123 + l6/73 f IO; nonpanickers: II9 + l2/73 & 9) or placebo infusions (panickers: 126
@ 1987 Elsevier Science Publishers B.V
264
Table 1. Baseline and preinfusion patient nonpanickers
Systolic blood pressure Controls (n = 25) Patients (n = 59) Panickers
blood pressures: Controls, patient panickers, and infusion
infusion
Infusion
Baseline
I
ii
ill
116+12 123 + 10
114*11 126+18 1281t 18 (n = 36) 124?~ 17 (n = 23)
1141t 16 123 zt 15 123 _t 14 (n = 30) 124 + 16 (n = 29)
114+13 122 & 14 125 * 16 (n = 32) 118f13 (n = 27)
69+10 75+11 75+12 (n = 36) 76+11 (n = 23)
68Itll 73f 10 75+11 (n = 30) 72zt 9 (n = 29)
66&10 71f 9 72+ 9 (n = 32) 70+ 9 (n = 27)
Nonpanickers Diastolic blood pressure Controls (n = 25) Patients (n = 59) Panickers
73* 77*
9 7
Nonpanickers
I!I I I /7i + 6; nonpanickers: 124 + 17/72 f IO). We used t tests instead of ANOVAs for these comparisons because of lack of consistency of subjects across different cells. These results, along with our previous findings on preinfusion heart rates, are in agreement with the findings of Cowley et al. (I 987) and suggest that autonomic measures such as heart rate and blood pressure may not be reliable indicators of central arousal in panic disorder patients. References Cowley, D.S., Hyde, T.S., Dager, S.R., and Dunner, D. Lactate infusions: The role of baseline anxiety. Psychiatry Research, 21, I69 ( 1987). Rainey, J.M., Pohl, R.B., Williams, M., Knitter, E., Freedman, R.R., and Ettedgui, E. A comparison of lactate and isoproterenol anxiety states. Psychopathology, 17, Suppl. I, 74(1984). Spitter, R., Endicott, J., and Robins, E. Research Diagnostic Criteria for a Selected Group of Functional Disorders. 3rd ed. New York State Psychiatric Institute, New York (1978). Yeragani, V.K., Baion, R., Pohi, R., Ortiz, A., Weinberg, P., and Rainey, J.M. Do higher preinfusion heart rates predict laboratory-induced panic attacks? Biological Psychiatry, 22, 554 (1987a). Yeragani, V.K., Pohi, R., Balon, R., Weinberg, P., Berchou, R., and Rainey, J.M. Pre-infusion anxiety predicts lactate-induced
panic attacks in normal controls. f’sychosomatic Medicine (in press a). Yeragani, V.K., Pohl, R., Rainey, J.M., Balon, R., Ortiz, A., Lycaki, H., and Gershon, S. Pre-infusion heart rates and laboratory-induced panic anxiety. Acta Psychiarrica Scandinavicu. 75, 5 I (I 987h). Yeragani, V.K., Rainey, J.M., Pohl, R., Balon, R., Berchou, R., Jolly, S., and Lycaki, H. Preinfusion anxiety and laboratory induced panic attacks in panic disorder patients. Journal of Clinical Psychiatry (in press h). Vikram K. Yeragani, M.D.1 Assistant Professor Robert Pohl, M.D. Associate Professor Richard Bulon, M.D. Assistant Professor Department of Psychiatry Wayne State University School of Medicine Detroit, MI 48201, USA Paul Sherwood, B.A. Statistician Lafayette Clinic Detroit, MI 48207, USA August 26, 1987 I. Reprint requests to Dr. V.K. Yeragani, Lafayette Clinic, 951 East Lafayette Ave., Detroit, MI 48207, USA.
263
Research. 22, 263-264
Elsevier
Letter Lactate Infusions: The Role of Baseline Anxiety and Autonomic Measures To the Editors:
We read with interest the article by Cowley et al. (1987) on lactate infusions and the role of baseline anxiety. They report that patients who had a typical panic attack with lactate had higher baseline anxiety symptom ratings, even though these did not fully account for differences in response to lactate. However, heart rate and blood pressure did not significantly differ between lactate responders and nonresponders. We have infused panic disorder patients and controls using sodium lactate, isoproterenol, and placebo in a double-blind randomized design. We found that preinfusion anxiety was significantly higher in those panic disorder patients and controls who panicked during lactate infusions compared to those who did not (Yeregani et al., in press a, in press b). The symptoms “afraid of going crazy” and “feeling unsteady” appeared to be the best predictors of a subsequent panic attack. There was no significant difference in the preinfusion heart rates of control panickers compared to nonpanickers (Yeragani et al., in press a). Although patients had a significant increase in heart rate just before infusions, there was no significant difference in preinfusion heart rates between panickers and nonpanickers for first infusion in our multiple infusion study (Yeragani et al., 1987h). We have also found no significant difference between the preinfusion heart rates of patients who panicked during placebo infusions and those who did not (Yeragani et al., 1987a). We have now compared baseline and preinfusion blood pressures between patients and controls and also between patient panickers and nonpanickers. Fifty-nine patients (35 females and 24 males) and 25 controls (9 females and I6 males) included in this study had baseline and preinfusion blood
0165-1781/87/$03.50
pressure data for all three infusions. All patients met Research Diagnostic Criteria (RDC) (Spitzer et al., 1978) for panic disorder. The subject selection and the infusion procedures have been previously described in detail (Rainey et al., 1984). Baseline blood pressures were recorded using the standard cuff technique and were done on the day of the patient’s initial psychiatric evaluation. Patients also knew that they would not receive an infusion at this time. Preinfusion blood pressures were recorded at 0 minutes using a Dinamap Vital Signs Monitor (Critikon, Tampa, FL) before the infusions were begun. A two-tailed t test did not reveal a significant difference in age between patients and controls (patients: 33.5 f 9.3; controls: 29.8 + 6.8; t = I .69, @= 82, NS). A two-way analysis of variance (ANOVA) (Table I) revealed that patients had significantly higher baseline and preinfusion systolic blood pressures for the three infusions (F = 9.1, df= I/81, p < 0.01). There were no other significant effects. The patients also had significantly higher diastolic pressures (F = 7.7, Gf = I /Sl, p < 0.01). There was also an overall significant decrease in diastolic blood pressure from baseline to the third infusion (F= 12.5, u”= 3/243,p < 0.01). There was no significant interaction effect. Fifty-one of 59 patients panicked during lactate, 42 of 59 during isoproterenol, and 7 of 52 during placebo infusions. Two-tailed t tests revealed no significant differences in the preinfusion systolic or diastolic blood pressures between patients who panicked and those who did not, either for first, second, or third infusions (Table I), or lactate (panickers: 124 + l5/72 + IO; nonpanickers: 125 + 20/73 + l4), isoproterenol (panickers: 123 + l6/73 f IO; nonpanickers: II9 + l2/73 & 9) or placebo infusions (panickers: 126
@ 1987 Elsevier Science Publishers B.V
264
Table 1. Baseline and preinfusion patient nonpanickers
Systolic blood pressure Controls (n = 25) Patients (n = 59) Panickers
blood pressures: Controls, patient panickers, and infusion
infusion
Infusion
Baseline
I
ii
ill
116+12 123 + 10
114*11 126+18 1281t 18 (n = 36) 124?~ 17 (n = 23)
1141t 16 123 zt 15 123 _t 14 (n = 30) 124 + 16 (n = 29)
114+13 122 & 14 125 * 16 (n = 32) 118f13 (n = 27)
69+10 75+11 75+12 (n = 36) 76+11 (n = 23)
68Itll 73f 10 75+11 (n = 30) 72zt 9 (n = 29)
66&10 71f 9 72+ 9 (n = 32) 70+ 9 (n = 27)
Nonpanickers Diastolic blood pressure Controls (n = 25) Patients (n = 59) Panickers
73* 77*
9 7
Nonpanickers
I!I I I /7i + 6; nonpanickers: 124 + 17/72 f IO). We used t tests instead of ANOVAs for these comparisons because of lack of consistency of subjects across different cells. These results, along with our previous findings on preinfusion heart rates, are in agreement with the findings of Cowley et al. (I 987) and suggest that autonomic measures such as heart rate and blood pressure may not be reliable indicators of central arousal in panic disorder patients. References Cowley, D.S., Hyde, T.S., Dager, S.R., and Dunner, D. Lactate infusions: The role of baseline anxiety. Psychiatry Research, 21, I69 ( 1987). Rainey, J.M., Pohl, R.B., Williams, M., Knitter, E., Freedman, R.R., and Ettedgui, E. A comparison of lactate and isoproterenol anxiety states. Psychopathology, 17, Suppl. I, 74(1984). Spitter, R., Endicott, J., and Robins, E. Research Diagnostic Criteria for a Selected Group of Functional Disorders. 3rd ed. New York State Psychiatric Institute, New York (1978). Yeragani, V.K., Baion, R., Pohi, R., Ortiz, A., Weinberg, P., and Rainey, J.M. Do higher preinfusion heart rates predict laboratory-induced panic attacks? Biological Psychiatry, 22, 554 (1987a). Yeragani, V.K., Pohi, R., Balon, R., Weinberg, P., Berchou, R., and Rainey, J.M. Pre-infusion anxiety predicts lactate-induced
panic attacks in normal controls. f’sychosomatic Medicine (in press a). Yeragani, V.K., Pohl, R., Rainey, J.M., Balon, R., Ortiz, A., Lycaki, H., and Gershon, S. Pre-infusion heart rates and laboratory-induced panic anxiety. Acta Psychiarrica Scandinavicu. 75, 5 I (I 987h). Yeragani, V.K., Rainey, J.M., Pohl, R., Balon, R., Berchou, R., Jolly, S., and Lycaki, H. Preinfusion anxiety and laboratory induced panic attacks in panic disorder patients. Journal of Clinical Psychiatry (in press h). Vikram K. Yeragani, M.D.1 Assistant Professor Robert Pohl, M.D. Associate Professor Richard Bulon, M.D. Assistant Professor Department of Psychiatry Wayne State University School of Medicine Detroit, MI 48201, USA Paul Sherwood, B.A. Statistician Lafayette Clinic Detroit, MI 48207, USA August 26, 1987 I. Reprint requests to Dr. V.K. Yeragani, Lafayette Clinic, 951 East Lafayette Ave., Detroit, MI 48207, USA.