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TRANSIENT BRADYCARDIA ASSOCIATED WITH EXTRADURAL BLOOD PATCH AFTER INADVERTENT DURAL PUNCTURE IN PARTURIENTS
British Journal of Anaesthesia 1992; 69: 401^03
TRANSIENT BRADYCARDIA ASSOCIATED WITH EXTRADURAL BLOOD PATCH AFTER INADVERTENT DURAL PUNCTURE IN PARTURIENTS P. J. D. ANDREWS, W. E. ACKERMAN, M. JUNEJA, V. CASES-CRISTOBAL AND B. M. RIGOR
We have studied prospective/y 10 ASA I or II postpartum patients after inadvertent dura/ puncture during labour. An extradural blood patch (autologous blood 15 ml) was performed within 18 h of delivery, with continuous EEG, upper facial EMG (Datex: Anesthesia and Brain Activity Monitor), pulse oximetry and heart rate measurement before, during and for 30 min after extradural injection. Non-invasive arterial pressure measurements (Dinamap) were recorded at 5-min intervals. After extradural blood patch, a statistically significant (Student's t test, P < 0.05) decrease in heart rate, from a mean baseline of 88.6 (SD 7.31) beat min'1 to 51.3 (7.6) beatmin~1, occurred within 122.6 (16.9) s from the time of the EBP. Bradycardia was observed for a mean duration of 12.4 (1.1) s. Upper facial EMG, EEG, Sp02 and arterial pressure did not change. KEY WORDS Anaesthetic techniques: extradural. Complications: headache.
Extradural blood patch is one of several treatments recommended for headache after dural puncture. However, neurological sequelae, including seizures [1], have been documented after the technique. Recent work suggests that an increase in intracranial pressure (ICP) occurs after extradural blood patch [2]. The purpose of this study was to document the physiological changes that happen at the time of and immediately after extradural blood patch. METHODS AND RESULTS
After obtaining Institutional Review Board approval and patient informed consent, we examined the physiological effects of extradural blood patch in 10 ASA I or II postpartum patients requesting this treatment.for,rjostdural puncture headache. Each patient had an extradural blood patch performed while in the sitting position. Using an aseptic technique, we administered autologous blood 15 ml at a rate of 0.5 ml s"1, pausing for 10 s after each 5-ml increment to assess patient discomfort. The left lateral position was adopted immediately after removal of the Tuohy needle.
EEG (zero-crossing frequency and rms-integrated Amplitude; ZXF and MIAEEQ, respectively), upper facial EMG (Datex Anesthesia and Brain Activity Monitor (ABM), Datex Instrumentarium Oy, Helsinki, Finland), ECG (limb lead II), pulse oximetry and heart rate (Datex Oscar pulse oximeter) were monitored continuously, before, during and for 30 min after extradural blood patch. Heart rate changes were obtained from the pulse oximeter with the manufacturer's finger probe on the index finger. Heart rate fluctuations caused by movement artefact were detected by plethysmographic interference and rejected. Arterial pressure was measured noninvasively every 5 min during that time (Dinamap, Critikon, CA, U.S.A.). EEG/EMG monitoring was undertaken with a Datex ABM that analysed biopotentials obtained from adhesive paediatric ECG electrodes (Red Dot infant monitoring electrode, 3M, St Paul, MN, U.S.A.) placed on the mid-forehead and mastoid process. The signal was filtered selectively to obtain spontaneous frontalis EMG (65-300 Hz) and EEG (1.5-25 Hz). Additional filtering removed the d.c. component of the a.c. signal, which prevented inaccurancies in zero-crossing frequency determination related to fluctuations in electrode impedance. Scaling of the EMG/EEG traces was non-linear and the display algorithm further modified the output of the log amplifiers to accentuate low output changes. The digital output from the ABM RS232 interface was converted to give a linear scale for analysis (see Appendix). The maximum changes in the five variables, arterial pressure, heart rate, ZXF, MIA EE0 and EMG were analysed. Statistics The data were analysed using Student's t test, with each patient acting as her own control. Bonferroni correction was made for the multiple withingroup comparisons (P*5). Significance at the 5% PETER J. D. ANDREWS, F.R.C.ANAES.; VICTORIA CASES-CRISTOBAL, M.D.; BENJAMIN M. RIGOR, M.D. ; Department of Anesthesiology,
University of Louisville, School of Medicine, 40292 Louisville, Kentucky, U.S.A. WILLIAM E. ACKERMAN, M.D.; MUSHTAQUE
JUNEJA, F.R.C.ANAES.; Norton Hospital, Alliant Health Systems, 40291 Louisville, Kentucky, U.S.A. Accepted for Publication: May 26, 1992. Correspondence to P.J.D.A.
Downloaded from http://bja.oxfordjournals.org/ at The University of British Colombia Library on July 7, 2015
SUMMARY
BRITISH JOURNAL OF ANAESTHESIA
402 TABLE I. Physiological changes associated with extradural blood patch (EBP) (mean (SD)). ZXF = Zero-crossing frequency; FEMG = upper facial spontaneous electromyography; MIAEEG = rmsinugraied amplitude; AP = mean arterial pressure
Heart rate (beat min"1) Spo, (%) FEMG (uV) ZXF (Hz) MIA EE0 (uV) AP (mm Hg)
Before EBP
After EBP
88.6 (7.3)
51.3 (7.6)
96 5.1 5.3 60.7 76.5
97 4.6 5.6 48.9 68.9
(2) (1.5) (1.1) (13.4) (6.6)
(2.2) (1.5) (1.6) (11.9) (6.8)
COMMENT
At full term there is an increase in blood volume within the extradural veins, a reduction in cerebrospinal fluid (CSF) surrounding the spinal cord and an increase in CSF pressure during the second stage of labour. Therefore the compliance of the extradural space is reduced. Injection of blood into the extradural space may cause an increase in ICP lasting 1-2 min [2], suggesting a Cushing response as the aetiology of the reduction in heart rate. There was no significant change in arterial pressure in this study, but a transient increase would have been missed with the frequency at which arterial pressure was measured. More frequent measurement was avoided, as patient discomfort caused by cuff inflation may have confounded the study. Postdural puncture headache is described as resulting from continued CSF leakage. In this study, extradural blood patch was performed within 18 h of delivery. Whole blood is a non-Newtonian fluid with a viscosity several times that of water which depends principally upon the PCV (reduced postpartum), and to a lesser extent plasma proteins (increased postpartum), blood flow velocity (an inverse relationship exists) and the Fahraeud-Linquist effect (rouleaux formation). Clot formation also impedes the removal of blood from the extradural space. This may further compound the problems discussed above. A temporal relationship between ICP and facial EMG fluctuations has been reported, the latter increasing consistently 30 s after an increase in ICP [3]. However, an increase in facial EMG was not detected in this study. Measurement of EEG (ZXF
(1) [FeBalt:cntalyst]
(2)
Free radicals can also be formed by mechanical forces, including homolytic breaking of main chain bonds in polymers and charge transfer (the triboelectric effect) [5]. Because of their reactivity, most free radicals exist only at small concentrations (10~4-10~9 mol litre"1) and do not travel from the site of formation. However, although the initial free radical produces only local effects, the secondary radicals formed by chain reactions initiated by the free radical, and the degradation products produced by reactions involving free radicals, can have biological effects distant from the site where the first free radicals were produced [4]. Free radicals may alter transmembrane movement of ions through membrane channels, including ion exchange mechanisms in the cardiac sarcolemma. Primary and secondary free radical injury may have a profound effect on the electrical function of the myocardium [6]. It would appear that extradural injection of 15 ml of whole blood in the immediate postpartum period caused a decrease in heart rate. As a result of our preliminary findings, we recommend ECG monitoring and care in the use of an extradural blood patch in patients with pre-existing cardiac disease or intracranial pathology.
APPENDIX The formula below produces a curve that is very close to that of the actual output of the ABM:
Y= — +0.6 V41/
For byte values less than 168 (3 uV) there is some loss of accuracy and the formula below was used: y=(*x0.0198-3.3) + 3 These formulae were entered into a spread sheet macro to convert the ABM byte output into microvolts.
REFERENCES 1. Bolton VE, Leicht CH, Scanlon TS. Postpartum seizures after epidural blood patch and intravenous caffeine sodium benzoate. Anesthesiology 1989; 70: 146-149.
Downloaded from http://bja.oxfordjournals.org/ at The University of British Colombia Library on July 7, 2015
level was taken to reject the Null hypothesis. Results are expressed as mean (SD) unless otherwise specified. The average weight of the patients was 67.5 (8) kg and mean age was 22 (4) yr. Each postpartum woman exhibited a statistically significant (Student's t test, P < 0.05, with each patient serving as her own control) decrease in heart rate from a mean baseline of 88.6 (7.3) beat min"1 to 51.3 (7.6) beat min"1 within 122.6 (16.9) s from the time of the extradural blood patch and this reduction in heart rate was recorded for 12.4 (1.1) s. There was no significant change in arterial pressure, >SpOt, upper facial EMG or EEG (ZXF and MIAEEG) (table I).
and MIAEEG) with the Datex ABM in awake patients is likely to have considerable contamination from low frequency scalp EMG and this may have masked any changes in true EEG. There was a reduction in MIABEC. An alternative explanation for the bradycardia associated with extradural blood patch is formation of free radicals (R'). Free radical formation in this situation may have been the result of a reaction between ferrous ions and hydrogen peroxide, the Fenton reaction (equation (1) below) or the ironcatalysed Haber-Weiss type reaction (equation (2) below) [4]:
EXTRADURAL BLOOD PATCH AND BRADYCARDIA 2. Ramsay M, Roberts C. Epidural injection does cause an increase in CSF pressure. Anesthesia and Analgesia 1991; 73: 668. 3. Paloheimo M. Quantitative surface electromyography applications in anaesthcsiology and critical care. Ada Anaesthcsiologica Scandinavica 1990; (Suppl. 93): 34. 4. Dunford HB. Free radicals in iron containing systems. Free Radical Biology and Medicine 1987; 3: 405-^421.
403
Symons MC. Formation of radicals by mechanical processes. Free Radical Research Communications 1988; 5: 131-139. Barrington PL. Effects of free radicals on the electrophysiological function of cardiac membranes. Free Radical Biology and Medicine 1990; 9: 355-365.
Downloaded from http://bja.oxfordjournals.org/ at The University of British Colombia Library on July 7, 2015
TRANSIENT BRADYCARDIA ASSOCIATED WITH EXTRADURAL BLOOD PATCH AFTER INADVERTENT DURAL PUNCTURE IN PARTURIENTS P. J. D. ANDREWS, W. E. ACKERMAN, M. JUNEJA, V. CASES-CRISTOBAL AND B. M. RIGOR
We have studied prospective/y 10 ASA I or II postpartum patients after inadvertent dura/ puncture during labour. An extradural blood patch (autologous blood 15 ml) was performed within 18 h of delivery, with continuous EEG, upper facial EMG (Datex: Anesthesia and Brain Activity Monitor), pulse oximetry and heart rate measurement before, during and for 30 min after extradural injection. Non-invasive arterial pressure measurements (Dinamap) were recorded at 5-min intervals. After extradural blood patch, a statistically significant (Student's t test, P < 0.05) decrease in heart rate, from a mean baseline of 88.6 (SD 7.31) beat min'1 to 51.3 (7.6) beatmin~1, occurred within 122.6 (16.9) s from the time of the EBP. Bradycardia was observed for a mean duration of 12.4 (1.1) s. Upper facial EMG, EEG, Sp02 and arterial pressure did not change. KEY WORDS Anaesthetic techniques: extradural. Complications: headache.
Extradural blood patch is one of several treatments recommended for headache after dural puncture. However, neurological sequelae, including seizures [1], have been documented after the technique. Recent work suggests that an increase in intracranial pressure (ICP) occurs after extradural blood patch [2]. The purpose of this study was to document the physiological changes that happen at the time of and immediately after extradural blood patch. METHODS AND RESULTS
After obtaining Institutional Review Board approval and patient informed consent, we examined the physiological effects of extradural blood patch in 10 ASA I or II postpartum patients requesting this treatment.for,rjostdural puncture headache. Each patient had an extradural blood patch performed while in the sitting position. Using an aseptic technique, we administered autologous blood 15 ml at a rate of 0.5 ml s"1, pausing for 10 s after each 5-ml increment to assess patient discomfort. The left lateral position was adopted immediately after removal of the Tuohy needle.
EEG (zero-crossing frequency and rms-integrated Amplitude; ZXF and MIAEEQ, respectively), upper facial EMG (Datex Anesthesia and Brain Activity Monitor (ABM), Datex Instrumentarium Oy, Helsinki, Finland), ECG (limb lead II), pulse oximetry and heart rate (Datex Oscar pulse oximeter) were monitored continuously, before, during and for 30 min after extradural blood patch. Heart rate changes were obtained from the pulse oximeter with the manufacturer's finger probe on the index finger. Heart rate fluctuations caused by movement artefact were detected by plethysmographic interference and rejected. Arterial pressure was measured noninvasively every 5 min during that time (Dinamap, Critikon, CA, U.S.A.). EEG/EMG monitoring was undertaken with a Datex ABM that analysed biopotentials obtained from adhesive paediatric ECG electrodes (Red Dot infant monitoring electrode, 3M, St Paul, MN, U.S.A.) placed on the mid-forehead and mastoid process. The signal was filtered selectively to obtain spontaneous frontalis EMG (65-300 Hz) and EEG (1.5-25 Hz). Additional filtering removed the d.c. component of the a.c. signal, which prevented inaccurancies in zero-crossing frequency determination related to fluctuations in electrode impedance. Scaling of the EMG/EEG traces was non-linear and the display algorithm further modified the output of the log amplifiers to accentuate low output changes. The digital output from the ABM RS232 interface was converted to give a linear scale for analysis (see Appendix). The maximum changes in the five variables, arterial pressure, heart rate, ZXF, MIA EE0 and EMG were analysed. Statistics The data were analysed using Student's t test, with each patient acting as her own control. Bonferroni correction was made for the multiple withingroup comparisons (P*5). Significance at the 5% PETER J. D. ANDREWS, F.R.C.ANAES.; VICTORIA CASES-CRISTOBAL, M.D.; BENJAMIN M. RIGOR, M.D. ; Department of Anesthesiology,
University of Louisville, School of Medicine, 40292 Louisville, Kentucky, U.S.A. WILLIAM E. ACKERMAN, M.D.; MUSHTAQUE
JUNEJA, F.R.C.ANAES.; Norton Hospital, Alliant Health Systems, 40291 Louisville, Kentucky, U.S.A. Accepted for Publication: May 26, 1992. Correspondence to P.J.D.A.
Downloaded from http://bja.oxfordjournals.org/ at The University of British Colombia Library on July 7, 2015
SUMMARY
BRITISH JOURNAL OF ANAESTHESIA
402 TABLE I. Physiological changes associated with extradural blood patch (EBP) (mean (SD)). ZXF = Zero-crossing frequency; FEMG = upper facial spontaneous electromyography; MIAEEG = rmsinugraied amplitude; AP = mean arterial pressure
Heart rate (beat min"1) Spo, (%) FEMG (uV) ZXF (Hz) MIA EE0 (uV) AP (mm Hg)
Before EBP
After EBP
88.6 (7.3)
51.3 (7.6)
96 5.1 5.3 60.7 76.5
97 4.6 5.6 48.9 68.9
(2) (1.5) (1.1) (13.4) (6.6)
(2.2) (1.5) (1.6) (11.9) (6.8)
COMMENT
At full term there is an increase in blood volume within the extradural veins, a reduction in cerebrospinal fluid (CSF) surrounding the spinal cord and an increase in CSF pressure during the second stage of labour. Therefore the compliance of the extradural space is reduced. Injection of blood into the extradural space may cause an increase in ICP lasting 1-2 min [2], suggesting a Cushing response as the aetiology of the reduction in heart rate. There was no significant change in arterial pressure in this study, but a transient increase would have been missed with the frequency at which arterial pressure was measured. More frequent measurement was avoided, as patient discomfort caused by cuff inflation may have confounded the study. Postdural puncture headache is described as resulting from continued CSF leakage. In this study, extradural blood patch was performed within 18 h of delivery. Whole blood is a non-Newtonian fluid with a viscosity several times that of water which depends principally upon the PCV (reduced postpartum), and to a lesser extent plasma proteins (increased postpartum), blood flow velocity (an inverse relationship exists) and the Fahraeud-Linquist effect (rouleaux formation). Clot formation also impedes the removal of blood from the extradural space. This may further compound the problems discussed above. A temporal relationship between ICP and facial EMG fluctuations has been reported, the latter increasing consistently 30 s after an increase in ICP [3]. However, an increase in facial EMG was not detected in this study. Measurement of EEG (ZXF
(1) [FeBalt:cntalyst]
(2)
Free radicals can also be formed by mechanical forces, including homolytic breaking of main chain bonds in polymers and charge transfer (the triboelectric effect) [5]. Because of their reactivity, most free radicals exist only at small concentrations (10~4-10~9 mol litre"1) and do not travel from the site of formation. However, although the initial free radical produces only local effects, the secondary radicals formed by chain reactions initiated by the free radical, and the degradation products produced by reactions involving free radicals, can have biological effects distant from the site where the first free radicals were produced [4]. Free radicals may alter transmembrane movement of ions through membrane channels, including ion exchange mechanisms in the cardiac sarcolemma. Primary and secondary free radical injury may have a profound effect on the electrical function of the myocardium [6]. It would appear that extradural injection of 15 ml of whole blood in the immediate postpartum period caused a decrease in heart rate. As a result of our preliminary findings, we recommend ECG monitoring and care in the use of an extradural blood patch in patients with pre-existing cardiac disease or intracranial pathology.
APPENDIX The formula below produces a curve that is very close to that of the actual output of the ABM:
Y= — +0.6 V41/
For byte values less than 168 (3 uV) there is some loss of accuracy and the formula below was used: y=(*x0.0198-3.3) + 3 These formulae were entered into a spread sheet macro to convert the ABM byte output into microvolts.
REFERENCES 1. Bolton VE, Leicht CH, Scanlon TS. Postpartum seizures after epidural blood patch and intravenous caffeine sodium benzoate. Anesthesiology 1989; 70: 146-149.
Downloaded from http://bja.oxfordjournals.org/ at The University of British Colombia Library on July 7, 2015
level was taken to reject the Null hypothesis. Results are expressed as mean (SD) unless otherwise specified. The average weight of the patients was 67.5 (8) kg and mean age was 22 (4) yr. Each postpartum woman exhibited a statistically significant (Student's t test, P < 0.05, with each patient serving as her own control) decrease in heart rate from a mean baseline of 88.6 (7.3) beat min"1 to 51.3 (7.6) beat min"1 within 122.6 (16.9) s from the time of the extradural blood patch and this reduction in heart rate was recorded for 12.4 (1.1) s. There was no significant change in arterial pressure, >SpOt, upper facial EMG or EEG (ZXF and MIAEEG) (table I).
and MIAEEG) with the Datex ABM in awake patients is likely to have considerable contamination from low frequency scalp EMG and this may have masked any changes in true EEG. There was a reduction in MIABEC. An alternative explanation for the bradycardia associated with extradural blood patch is formation of free radicals (R'). Free radical formation in this situation may have been the result of a reaction between ferrous ions and hydrogen peroxide, the Fenton reaction (equation (1) below) or the ironcatalysed Haber-Weiss type reaction (equation (2) below) [4]:
EXTRADURAL BLOOD PATCH AND BRADYCARDIA 2. Ramsay M, Roberts C. Epidural injection does cause an increase in CSF pressure. Anesthesia and Analgesia 1991; 73: 668. 3. Paloheimo M. Quantitative surface electromyography applications in anaesthcsiology and critical care. Ada Anaesthcsiologica Scandinavica 1990; (Suppl. 93): 34. 4. Dunford HB. Free radicals in iron containing systems. Free Radical Biology and Medicine 1987; 3: 405-^421.
403
Symons MC. Formation of radicals by mechanical processes. Free Radical Research Communications 1988; 5: 131-139. Barrington PL. Effects of free radicals on the electrophysiological function of cardiac membranes. Free Radical Biology and Medicine 1990; 9: 355-365.
Downloaded from http://bja.oxfordjournals.org/ at The University of British Colombia Library on July 7, 2015