RESEARCH NEWS
Anesthetic Drugs and Malignant Hyperthermia Mary W. Stewart, PhD, RN MALIGNANT HYPERTHERMIA (MH), a severe life-threatening condition, has long been a concern for perianesthesia nurses. For many decades, we have studied MH and sought ways to diagnose it early and intervene quickly. Every patient admitted for anesthesia care is assessed for the potential of MH; suspected cases are addressed meticulously. Visoiu et al direct their attention to this ‘‘old topic’’ in hopes of shedding ‘‘new light’’ on its potential danger. Anesthetic Drugs and Onset of Malignant Hyperthermia by Visoiu M, Young MC, Wieland K, Brandom BW. Anesth Analg. 2014;118(2):388-396.
Background and Purpose Previous research has taught us that MH is a greater risk when patients receive inhaled anesthetics in combinations with succinylcholine. Nonetheless, MH has also been suspected in cases where no anesthesia has been used. Other variables of interest include the number of first signs of MH, severity of the symptoms, patient age and gender, and year of MH episode. Although a keen awareness of MH exists, anesthetic practices have improved over the years. These changes may have an influence on the occurrence, timing, or severity of MH and are worthy of exploration. The purpose of this study was to determine if the time between the start of anesthetic administration and MH onset (recognition of first sign of MH) varies with the type of inhaled anesthetic used. Mary W. Stewart, PhD, RN, Professor and Director of the PhD program, Special Assistant to the Dean, School of Nursing, University of Mississippi Medical Center, Jackson, MS. Conflict of interest: None to report. Address correspondence to Mary W. Stewart, University of Mississippi Medical Center, School of Nursing, 2500 North State Street, Jackson, MS 39216-4505; e-mail address: [email protected]. Ó 2014 by American Society of PeriAnesthesia Nurses 1089-9472/$36.00 http://dx.doi.org/10.1016/j.jopan.2014.03.002
Journal of PeriAnesthesia Nursing, Vol 29, No 3 (June), 2014: pp 253-255
Methodology and Analysis Appropriately, three of the four authors disclosed their relationships and past funding support from the Malignant Hyperthermia Association of the United States. The University of Pittsburgh Institutional Review Board approved the study. Existing data were used in the analysis, and the study was exempted from a full committee review. Data from January 1987 to January 2010 were drawn from the North American Malignant Hyperthermia Registry. Specifically, reports of Adverse Metabolic/Musculoskeletal Reactions to Anesthesia (AMRA) from the United States and Canada were included in the analysis. A total of 712 AMRAs were critiqued for the following: inhaled anesthetics used, succinylcholine use, patient gender, patient age at the time of event, notes of the MH event, and a clinical grading scale (CGS) score. After evaluating the cases as possible MH, fulminant MH, or non-MH, 477 cases met the criteria for inclusion into the study. A key variable was MH onset time, which the authors defined as ‘‘the time between the beginning of anesthetic administration and documentation of the first sign of MH’’ (p. 389). The MH onset times were recorded into four different groups: (1) patients who received an inhaled anesthetic and succinylcholine; (2) patients who received an inhaled anesthetic only; (3) patients who received succinylcholine only; and (4) patients who did not receive an inhaled anesthetic or succinylcholine. The inhaled anesthetics were limited to halothane, sevoflurane, desflurane, and isoflurane. Patients who received more than one inhaled anesthetic were excluded from this analysis. Another important variable was first MH sign, defined as the occurrence of one or simultaneous occurrence of more than one of the following: ‘‘hypercarbia, sinus tachycardia, masseter muscle spasm, generalized muscle rigidity, tachypnea, cyanosis, skin mottling, rapidly increasing
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temperature, sweating, hyperkalemia, ventricular tachycardia, ventricular fibrillation, cola-colored urine, and excessive bleeding’’ (p. 389). Descriptive statistics were reported for the continuous data. For the continuous data that were not normally distributed, nonparametric tests of difference (Mann-Whitney or Kruskal-Wallis) were used. Chi-square test compared gender frequency. Spearman correlation coefficient was used to look at the relationship of MH onset time with year of event, the CGS score, and the patient’s age. Additionally, factors associated with the documentation of MH onset time were evaluated through regression analysis.
Results Twenty-one of the 477 cases lacked documentation of the patient’s age. Of the 456 that did report age, the mean was 23.7 years. Seventy percent (N 5 344) were men, and 29.1% (N 5 139) were women; gender was not specified in four cases. More women than men received succinylcholine (P 5 .032). The median CGS for the 477 cases was 48, indicating ‘‘very likely MH.’’ The median year of the event occurrence was 1997 (28 cases), with the highest incidence occurring in 1992 (56 cases). Of the 477 cases, the majority (257 or 53.9%) was in the group that received both inhaled anesthetic and succinylcholine, 199 or 41.7% received only inhaled anesthetics, 14 or 2.9% received succinylcholine only, and seven patients were not exposed to either anesthetic. MH onset time was significantly different among the groups receiving an inhaled anesthetic, regardless of the use of succinylcholine. In the absence of succinylcholine, halothane use was associated with shorter MH onset time compared with desflurane (P 5 .001) and isoflurane (P , .0001) but not with sevoflurane (P 5 .261). MH onset time was also shorter when comparing sevoflurane and desflurane (P 5 .047) and sevoflurane and isoflurane (P 5 .001). When succinylcholine was used in conjunction with an inhaled anesthetic, the MH onset time was always shorter. In this group, succinylcholine with inhaled anesthetic, the onset times were significantly shorter between halothane and sevoflurane (P 5 .041), halothane and desflurane
(P 5 .014), and halothane and isoflurane (P , .001). No differences existed among onset times when comparing sevoflurane, desflurane, and isoflurane. Of the 322 cases with a documented first unique sign of MH, the most common was hypercarbia (30.7%), followed by masseter muscle spasm (24.8%), and sinus tachycardia (21.1%). When the first signs were analyzed according to the four types of inhaled anesthetics, the frequency of masseter spasm was the first MH sign in those who received halothane (60.8%), followed by isoflurane (15.3%), desflurane (13.5%), and sevoflurane (12.9%). These differences were significant at P , .0005. Overall, when there was one unique first sign of MH, median onset time was 45 minutes. In the 155 patients with multiple first signs of MH, the median onset time was 55 minutes (nonsignificant). No significant differences were found in MH onset time and unique or multiple first signs when comparing those who received succinylcholine and those who did not. The primary variable of interest—MH onset time—differed with the type of first sign of MH. Masseter spasm was associated with the shortest onset time at 22.5 minutes when no succinylcholine was used and 5 minutes when succinylcholine was used. When both succinylcholine and halothane were used, the occurrence of masseter spasm was significantly more common (P , .0005) compared with its occurrence with the other inhaled anesthetics. Another interesting finding was the correlation between year of the MH event, onset time, and anesthetic exposure. MH onset time was shorter (P , .0005) before 1997 compared with after 1997. Exposure to succinylcholine and the four inhaled anesthetics differed significantly (P , .0005) before and after 1997. Masseter spasm was more commonly reported before 1997 (35.4%) versus after 1997 (11.5%).
Conclusions Because some individuals (N 5 7) without anesthesia exposure experienced an MH event, as defined in this study, it implies that no guarantee can be given that MH may not occur. Most likely, these individuals were identified as high risk preoperatively, and the anesthesia provider chose
RESEARCH NEWS
not to expose them to succinylcholine or the inhaled anesthetics included in this analysis. Nonetheless, these cases were identified as MH possible of fulminant, and identification of signs of MH was long after the start of anesthesia. These researchers explored MH onset time compared with different initial signs. In this study, masseter spasm was linked to the shortest onset time. Unsurprisingly, anesthesia providers often notice masseter spasm the first time during attempts to open the airway. When masseter spasm was controlled, the onset of MH was longer. Perhaps, early signs were missed, and the continued use of inhaled anesthetics made it more difficult to remove the anesthetic from the muscle. With the decline in use of halothane and succinylcholine, the first signs of MH are occurring later. Nonetheless, the use of isoflurane and sevoflurane show comparable correlations with MH as halothane in this study, although the onset of MH, or appearance of first sign of MH, was longer.
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PeriAnesthesia Nursing Implications For the foreseeable future, perianesthesia nurses will need to remain vigilant in our assessment of malignant hyperthermia. As these results indicate, in more recent years—with the use of inhaled anesthetics other than halothane—the onset of MH seems to be occurring later. Additionally, older patients with their accompanying slower metabolic rates may show signs of MH later than predicted in younger patients. Finally, these findings indicate that MH can occur in the absence of these anesthetic drugs. With the quick rotation through the post anesthesia care unit for many patients, those of us with expertise in MH may not be the immediate care provider when those first symptoms appear. Therefore, educating our peers, patients, and families about the signs to observe remains a primary responsibility in protecting our patients from harm. Letting our guard down is not an option.
Anesthetic Drugs and Malignant Hyperthermia Mary W. Stewart, PhD, RN MALIGNANT HYPERTHERMIA (MH), a severe life-threatening condition, has long been a concern for perianesthesia nurses. For many decades, we have studied MH and sought ways to diagnose it early and intervene quickly. Every patient admitted for anesthesia care is assessed for the potential of MH; suspected cases are addressed meticulously. Visoiu et al direct their attention to this ‘‘old topic’’ in hopes of shedding ‘‘new light’’ on its potential danger. Anesthetic Drugs and Onset of Malignant Hyperthermia by Visoiu M, Young MC, Wieland K, Brandom BW. Anesth Analg. 2014;118(2):388-396.
Background and Purpose Previous research has taught us that MH is a greater risk when patients receive inhaled anesthetics in combinations with succinylcholine. Nonetheless, MH has also been suspected in cases where no anesthesia has been used. Other variables of interest include the number of first signs of MH, severity of the symptoms, patient age and gender, and year of MH episode. Although a keen awareness of MH exists, anesthetic practices have improved over the years. These changes may have an influence on the occurrence, timing, or severity of MH and are worthy of exploration. The purpose of this study was to determine if the time between the start of anesthetic administration and MH onset (recognition of first sign of MH) varies with the type of inhaled anesthetic used. Mary W. Stewart, PhD, RN, Professor and Director of the PhD program, Special Assistant to the Dean, School of Nursing, University of Mississippi Medical Center, Jackson, MS. Conflict of interest: None to report. Address correspondence to Mary W. Stewart, University of Mississippi Medical Center, School of Nursing, 2500 North State Street, Jackson, MS 39216-4505; e-mail address: [email protected]. Ó 2014 by American Society of PeriAnesthesia Nurses 1089-9472/$36.00 http://dx.doi.org/10.1016/j.jopan.2014.03.002
Journal of PeriAnesthesia Nursing, Vol 29, No 3 (June), 2014: pp 253-255
Methodology and Analysis Appropriately, three of the four authors disclosed their relationships and past funding support from the Malignant Hyperthermia Association of the United States. The University of Pittsburgh Institutional Review Board approved the study. Existing data were used in the analysis, and the study was exempted from a full committee review. Data from January 1987 to January 2010 were drawn from the North American Malignant Hyperthermia Registry. Specifically, reports of Adverse Metabolic/Musculoskeletal Reactions to Anesthesia (AMRA) from the United States and Canada were included in the analysis. A total of 712 AMRAs were critiqued for the following: inhaled anesthetics used, succinylcholine use, patient gender, patient age at the time of event, notes of the MH event, and a clinical grading scale (CGS) score. After evaluating the cases as possible MH, fulminant MH, or non-MH, 477 cases met the criteria for inclusion into the study. A key variable was MH onset time, which the authors defined as ‘‘the time between the beginning of anesthetic administration and documentation of the first sign of MH’’ (p. 389). The MH onset times were recorded into four different groups: (1) patients who received an inhaled anesthetic and succinylcholine; (2) patients who received an inhaled anesthetic only; (3) patients who received succinylcholine only; and (4) patients who did not receive an inhaled anesthetic or succinylcholine. The inhaled anesthetics were limited to halothane, sevoflurane, desflurane, and isoflurane. Patients who received more than one inhaled anesthetic were excluded from this analysis. Another important variable was first MH sign, defined as the occurrence of one or simultaneous occurrence of more than one of the following: ‘‘hypercarbia, sinus tachycardia, masseter muscle spasm, generalized muscle rigidity, tachypnea, cyanosis, skin mottling, rapidly increasing
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temperature, sweating, hyperkalemia, ventricular tachycardia, ventricular fibrillation, cola-colored urine, and excessive bleeding’’ (p. 389). Descriptive statistics were reported for the continuous data. For the continuous data that were not normally distributed, nonparametric tests of difference (Mann-Whitney or Kruskal-Wallis) were used. Chi-square test compared gender frequency. Spearman correlation coefficient was used to look at the relationship of MH onset time with year of event, the CGS score, and the patient’s age. Additionally, factors associated with the documentation of MH onset time were evaluated through regression analysis.
Results Twenty-one of the 477 cases lacked documentation of the patient’s age. Of the 456 that did report age, the mean was 23.7 years. Seventy percent (N 5 344) were men, and 29.1% (N 5 139) were women; gender was not specified in four cases. More women than men received succinylcholine (P 5 .032). The median CGS for the 477 cases was 48, indicating ‘‘very likely MH.’’ The median year of the event occurrence was 1997 (28 cases), with the highest incidence occurring in 1992 (56 cases). Of the 477 cases, the majority (257 or 53.9%) was in the group that received both inhaled anesthetic and succinylcholine, 199 or 41.7% received only inhaled anesthetics, 14 or 2.9% received succinylcholine only, and seven patients were not exposed to either anesthetic. MH onset time was significantly different among the groups receiving an inhaled anesthetic, regardless of the use of succinylcholine. In the absence of succinylcholine, halothane use was associated with shorter MH onset time compared with desflurane (P 5 .001) and isoflurane (P , .0001) but not with sevoflurane (P 5 .261). MH onset time was also shorter when comparing sevoflurane and desflurane (P 5 .047) and sevoflurane and isoflurane (P 5 .001). When succinylcholine was used in conjunction with an inhaled anesthetic, the MH onset time was always shorter. In this group, succinylcholine with inhaled anesthetic, the onset times were significantly shorter between halothane and sevoflurane (P 5 .041), halothane and desflurane
(P 5 .014), and halothane and isoflurane (P , .001). No differences existed among onset times when comparing sevoflurane, desflurane, and isoflurane. Of the 322 cases with a documented first unique sign of MH, the most common was hypercarbia (30.7%), followed by masseter muscle spasm (24.8%), and sinus tachycardia (21.1%). When the first signs were analyzed according to the four types of inhaled anesthetics, the frequency of masseter spasm was the first MH sign in those who received halothane (60.8%), followed by isoflurane (15.3%), desflurane (13.5%), and sevoflurane (12.9%). These differences were significant at P , .0005. Overall, when there was one unique first sign of MH, median onset time was 45 minutes. In the 155 patients with multiple first signs of MH, the median onset time was 55 minutes (nonsignificant). No significant differences were found in MH onset time and unique or multiple first signs when comparing those who received succinylcholine and those who did not. The primary variable of interest—MH onset time—differed with the type of first sign of MH. Masseter spasm was associated with the shortest onset time at 22.5 minutes when no succinylcholine was used and 5 minutes when succinylcholine was used. When both succinylcholine and halothane were used, the occurrence of masseter spasm was significantly more common (P , .0005) compared with its occurrence with the other inhaled anesthetics. Another interesting finding was the correlation between year of the MH event, onset time, and anesthetic exposure. MH onset time was shorter (P , .0005) before 1997 compared with after 1997. Exposure to succinylcholine and the four inhaled anesthetics differed significantly (P , .0005) before and after 1997. Masseter spasm was more commonly reported before 1997 (35.4%) versus after 1997 (11.5%).
Conclusions Because some individuals (N 5 7) without anesthesia exposure experienced an MH event, as defined in this study, it implies that no guarantee can be given that MH may not occur. Most likely, these individuals were identified as high risk preoperatively, and the anesthesia provider chose
RESEARCH NEWS
not to expose them to succinylcholine or the inhaled anesthetics included in this analysis. Nonetheless, these cases were identified as MH possible of fulminant, and identification of signs of MH was long after the start of anesthesia. These researchers explored MH onset time compared with different initial signs. In this study, masseter spasm was linked to the shortest onset time. Unsurprisingly, anesthesia providers often notice masseter spasm the first time during attempts to open the airway. When masseter spasm was controlled, the onset of MH was longer. Perhaps, early signs were missed, and the continued use of inhaled anesthetics made it more difficult to remove the anesthetic from the muscle. With the decline in use of halothane and succinylcholine, the first signs of MH are occurring later. Nonetheless, the use of isoflurane and sevoflurane show comparable correlations with MH as halothane in this study, although the onset of MH, or appearance of first sign of MH, was longer.
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PeriAnesthesia Nursing Implications For the foreseeable future, perianesthesia nurses will need to remain vigilant in our assessment of malignant hyperthermia. As these results indicate, in more recent years—with the use of inhaled anesthetics other than halothane—the onset of MH seems to be occurring later. Additionally, older patients with their accompanying slower metabolic rates may show signs of MH later than predicted in younger patients. Finally, these findings indicate that MH can occur in the absence of these anesthetic drugs. With the quick rotation through the post anesthesia care unit for many patients, those of us with expertise in MH may not be the immediate care provider when those first symptoms appear. Therefore, educating our peers, patients, and families about the signs to observe remains a primary responsibility in protecting our patients from harm. Letting our guard down is not an option.
