Undergoing invasive procedures,

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1 ClinicalArticle Effects of Patient-Controlled Music Therapy During Coronary Angiography on Procedural Pain and Anxiety Distress Syndrome Kathy Bally, RN, BNSc, CCN(C) Debbie Campbell, RN, CCN(C) Kathy Chesnick, RN, MSc Joan E. Tranmer, RN, PhD Undergoing invasive s, such as coronary angiography, can be acutely stressful for Online To receive CE credit for this article, visit the American Association of Critical-Care Nurses (AACN) Web site at click on Education and select Continuing Education, or call AACN s Fax On Demand at (800) and request item No many patients. Many factors contribute to patients level of stress: previous experience, pain, anxiety, unfamiliar environment, and fear. Stress produces a physiological and biochemical response that is unique for each person with respect to duration, intensity, and overall impact. This response is elicited when stressors, such as pain or anxiety or a combination thereof, are physically and psychologically demanding for Authors All authors are employed at the Kingston General Hospital in Kingston, Ontario. Kathy Bally is a clinical instructor for the coronary care unit, cardiovascular laboratory, cardiology unit, and the cardiac devices clinic. Debbie Campbell is the regional cardiac care coordinator with the Cardiac Care Network and is project leader of multicenter trials in critical care. Kathy Chesnick is the professional practice leader in nursing at Kingston General Hospital and Hotel Dieu Hospital. Joan E. Tranmer is director of nursing research at Kingston General Hospital and an assistant professor in the school of nursing at Queen s University, Kingston, Ontario. To purchase reprints, contact The InnoVision Group, 101 Columbia, Aliso Viejo, CA Phone, (800) or (949) (ext 532); fax, (949) ; , [email protected]. the patient. The psychophysiological stress response involves activation of the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system and is characterized by increased heart rate, blood pressure, and cardiac output. The degree of the physiological stress response reflects the stress perceived and experienced. Obviously, this response increases the workload on a cardiovascular system that may already be compromised. Stress can be reduced by either removing the source of the stress or by mediating its effect through supportive interventions. Pain and anxiety are 2 common stressors in patients with cardiovascular conditions. Anxiety is an emotional state characterized by feelings of tension, nervousness, worry, apprehension, 50 CRITICALCARENURSE Vol 23, No. 2, APRIL 2003

2 and heightened activity of the autonomic nervous system. Spielberger 1 differentiates between state anxiety as a transitory emotional condition and trait anxiety as a stable predisposition to anxiety. Anxiety may bring about coping mechanisms to reduce the impact of the stress; but too much anxiety may interfere with cognitive ability to cope and lead to feelings of helplessness. Some anxiety is expected and may be beneficial during coronary angiography s, because it indicates that the patient is confronting and attuned to the demands of the and event. However, high anxiety may cause or potentiate an imbalance and create an unhealthy stress response. High anxiety, measured physiologically and with the State- Trait Anxiety Inventory (STAI), has been reported in cardiac patients in coronary care units 2-5 and after surgery. 6,7 Most nurses have observed that pain can cause or potentiate the level of anxiety. Pain during angiographic s may be associated with sheath insertion, immobilization, injection of contrast material, and balloon inflation. At Kingston General Hospital, Kingston, Ontario, patients are routinely administered an anxiolytic agent (ie, lorazepam) to help alleviate anxiety during the and a local anesthetic at the time of sheath insertion to alleviate pain. Despite these pharmacological measures and the usual supportive care provided by the nurses, indications of anxiety often occur in patients even during the. Nonpharmacological interventions, such as music therapy, have not yet been incorporated into usual care. Ideally, supportive care interventions should enhance patients ability to physically and cognitively (behaviorally) cope with the stress. Although the evidence is varied, the available research suggests that music therapy is an intervention that may be effective in mediating or reducing pain and anxiety. Music therapy is a nonpharmacological intervention that purportedly improves level of comfort and enhances well-being in patients by engaging the affective, cognitive, and sensory mechanisms. 8,9 Studies exploring the effectiveness of music therapy have produced mixed results. Stevens 10 examined patients response to music during operative s involving spinal, epidural, or local infiltration anesthesia: 75% of the patients rated the music as helpful, relaxing, and supportive. Participants stated that listening to music helped counterbalance the feeling of depersonalization associated with being in the hospital environment. Palakanis et al 11 reported the effect of music on patients anxiety during flexible sigmoidoscopy. They found that music was an effective anxiolytic; state anxiety scores were significantly less in the group of patients who listened to self-selected tapes during s than in patients who received the standard protocol. Conversely, music in combination with muscle relaxation was ineffective in reducing anxiety in patients admitted to a coronary care unit with unstable angina or acute myocardial infarction. 6 Good 12 reviewed the effects of music and relaxation on postoperative pain and concluded that relaxation and music were effective in reducing affective and observed pain in most studies but were less effective in reducing opioid intake and sensory pain. Methodological problems, such as inadequate sample size, poor measurement of pain, and no assurance of pretest equivalence reduced the validity of the study results reviewed by Good. Good recommended that randomized controlled trials be conducted within various clinical contexts to determine the effectiveness of music therapies on relevant outcomes for patients. Purpose The purpose of this research was to determine the effect of patientcontrolled music on the psychophysiological stress response to coronary angiography. The null hypothesis was that there would be no difference in levels of anxiety and pain, as measured by the patients own assessments and physiological monitoring, in patients who were offered the opportunity to listen to a self-selected audiotape of music before, during, and after coronary angiography in comparison to patients who were offered conventional care alone. Research Design and Methods Study Design, Setting, and Sample A pretest-posttest control group experimental study was conducted at Kingston General Hospital, a university-affiliated teaching hospital, between March 1999 and June This hospital is a tertiary cardiology referral center with a yearly diagnostic volume of approximately 1400 cases and an interventional volume of approximately 600 cases. The study took place in the cardiovascular laboratory. Registered nurses, cardiovascular technicians, and cardiologists provided patients care. Patients were eligible for inclusion if they were undergoing, for the first time, diagnostic coronary CRITICALCARENURSE Vol 23, No. 2, APRIL

3 angiography or a percutaneous intervention ; able to speak and read English; cognitively oriented to person, place, and time; and had no major auditory deficits. On the basis of the effectiveness of music therapy in lowering state anxiety in previous studies with patients who had myocardial infarction, 3,4 we estimated a sample size of 120 patients for a power of 80% and a significance α of.05. Patients were approached for participation during their outpatient cardiology clinic visit before the or while in the hospital. A research assistant contacted potential participants, described the study, and sought consent. Patients scheduled for either diagnostic coronary angiography or a percutaneous intervention who consented were immediately randomized to a control or experimental group by selecting a randomly generated group number sealed in an opaque envelope. The research protocol was reviewed and approved by the local research ethics board. Intervention Control Group Participants randomized to the control group received the standard care reflective of current practice. This care included a physical assessment before the, an explanation about the, routine administration of an anxiolytic (ie, lorazepam) and a local anesthetic, and administration of other medications, such as nitroglycerin, as needed. Experimental Group Participants randomized to the experimental group were provided, in addition to the usual care, the opportunity to listen before, during, and after the to a selfselected audiocassette tape via earphones. Music therapy began after the questionnaires were completed before the, continued as the patient desired during the, and ended just before the patient completed the questionnaire after the. The use of earphones was pretested during the angiographic to ensure that it did not affect the patient s ability to follow verbal instructions during the. Measures Data were collected from the questionnaires completed by the patients before and after the and from each patient s record. Anxiety and pain were measured at baseline and after the, just before removal of the arterial sheath. Apical heart rate and systolic and diastolic blood pressure were measured 4 times: (1) at baseline before the questionnaire was administered and on the patient s arrival at the holding area of the cardiovascular laboratory, (2) before the start of the, immediately after sheath insertion, (3) at the end of the angiographic and before transfer from the table, and (4) after the, No pain Figure 1 Visual analog scale used for pain measurements. Adapted from McGill Pain Questionnaire 13 Pain descriptors immediately before sheath removal. Anxiety was measured by using the STAI-Form Y-1. 1 The state anxiety scale measure reflects the subject s level of anxiety at a particular moment in time. The scale consists of 20 statements with responses on a 4-point Likert scale. Half of the items relate to the presence of apprehension, worry, or tension, and the remaining items reflect the absence of such states. The total score is the weighted sum of the 20 responses and ranges from 20 to 80: low anxiety (20-30), moderate anxiety (40-59), and high anxiety (60-80). The test-retest reliability correlation reported for the state scale was 0.16 to This low correlation was expected because the STAI is designed to measure situational anxiety. Alpha reliability coefficients obtained to measure internal consistency are reported as 0.91 to Pain was measured by using a visual analog scale and a descriptor scale (Figure 1). The visual analog scale is a unidimensional scale for quantifying intensity and is used extensively to measure such unpleasant symptoms as pain, fatigue, and dyspnea. The visual analog scale used in this study was 10 cm long, anchored with pain intensity extremes of no pain to worst possible pain. Interval level data were obtained by measur- Worst possible pain 0 No pain 1 Mild 2 Discomforting 3 Distressing 4 Horrible 5 Excruciating CRITICALCARENURSE Vol 23, No. 2, APRIL

4 ing the centimeters from the low end of each scale to the subject s mark. The descriptor scale contained 6 categorical descriptions of pain. 13 An external cardiac monitor was used to measure heart rate indirectly. Blood pressure was measured indirectly with a pressure dynamometer at baseline and after the but before sheath removal. Blood pressure was measured directly via arterial pressure monitoring after sheath insertion and at the end of the angiographic. Information on medications and complications was abstracted from patients records. Analysis All questionnaire and chart abstraction data were entered into a Microsoft Access database. All data from questionnaires were entered twice to ensure accuracy of data entry. Data were analyzed by using the SAS 8.5 statistical software package (SAS Institute, Cary, NC). To compare the groups at baseline, we performed an analysis of variance for continuous variables and a χ 2 test for categorical variables. To determine the effect of the intervention on levels of anxiety and pain, we performed an analysis of covariance, to control for baseline levels of anxiety and pain. Post hoc we performed a correlational and forward regression analysis to determine the relationships between anxiety and pain and the factors that contributed to elevated levels of anxiety. We used the conventional P less than.05 level of significance. Results Sample We asked 129 patients to participate; of these, 113 (87.6%) agreed to participate and were randomized to the control (n=55) and experimental (n=58) groups. We have complete data on 107 patients. Six patients (4 control, 2 experimental) were not included because the was canceled after their enrollment or they could not complete all the questionnaires because of complications. Enrolled patients, in both groups, were similar at baseline with respect to age, sex, and type of diagnostic performed (Table 1). As expected, both groups included slightly more men than women. Diagnostic angiography was the most common with a mean duration, defined as the time from placement on the table to the end of the, of approximately 45 minutes. Participants in the intervention group selected a variety of music, predominantly softer, more relaxing music (eg, classical, soft rock, relaxation, and easy country). Comparison Between Groups Both at baseline and after the, no significant differences Table 1 Characteristics of patients at enrollment* Characteristic Age, mean (SD), y Sex Female Male Actual Angiogram Angioplasty Angioplasty with stent Duration of, mean (SD), min Music selected Classical Soft rock Relaxation Country Other (ie, own) Control (n = 55) 58 (11) 25 (45) 30 (55) 46 (84) 7 (13) 43 (18) were apparent between groups in levels of state anxiety or pain intensity, and no differences were detected in change scores (Table 2). With use of the analysis of covariance and control for preintervention anxiety levels, we found no difference between groups in anxiety after the Group IN TESTS OF STATISTICAL significance, the alpha (α), also known as the P value, designates the level of probability of committing a type I error, that is rejecting the null hypothesis of no effect when actually it is true (ie, researcher concludes that a relationship or effect exists when in fact it does not). The beta error (β) designates the level of probability of committing a type II error, that is accepting the null hypothesis when it is false (ie, researcher concludes there is no relationship when one does exist). Experimental (n = 58) 59 (11) 24 (41) 34 (59) 45 (80) 9 (16) 48 (21) 16 (28) 9 (16) 11 (19) 16 (28) 5 (9) *Values are No. (%) of patients unless otherwise indicated. Two patients had the cancelled, one of them after music had been selected. P CRITICALCARENURSE Vol 23, No. 2, APRIL 2003

5 Table 2 Comparison of anxiety and pain between groups* Variable State anxiety scores, mean (SD) Before After Change score (after - before) Pain intensity scores, mean (SD), cm Before After Change score (after - before) Pain after None Mild Discomforting Distressing Horrible Excruciating Vasovagal reactions Extra analgesic medication given Extra anxiolytic medication given (F = 0.86, P =.36). Patients reported moderate levels of state anxiety before the. Anxiety decreased after the. Patients in both groups received an anxiolytic (lorazepam) before the but few received additional doses, and 43.9% (n = 47) received nitroglycerin or other medications such as heparin. The standardized Cronbach coefficient α for the anxiety scale was 0.92 at baseline and 0.89 after the. Angiographic s were not associated with postprocedural pain; most patients (n = 86, 80.4%) reported no pain after the. Heart rate and blood pressure (systolic and mean) were not significantly different at baseline, before the but after sheath insertion, at the end of the, or after the but before sheath removal (Figure 2). Heart rate increased and peaked at the end of Control (n = 51) 40.7 (12.6) 33.6 (9.6) -7.0 (10.8) 0.3 (1.2) 0.5 (1.2) 0.2 (0.6) 39 (76) 4 (8) 5 (10) 0 (0) 4 (8) Group Experimental (n = 56) 39.0 (10.8) 31.5 (9.7) -9.1 (12.1) 0.1 (0.4) 0.4 (1.0) 0.3 (0.9) 45 (80) 7 (12) 0 (0) 0 (0) the, and blood pressure (systolic and mean) peaked at the beginning of the, after the insertion of the sheath. The changes in heart rate and blood pressure (systolic, diastolic, and mean) were not significantly different at the 4 measurement points. Post hoc, we determined the relationships between levels of anxiety and pain before and after the (Table 3). Significant moderate correlations were found between anxiety before the and pain before the, anxiety after the, and pain after the. Pain before the and pain after the also had a moderate significant correlation. The forward stepwise regression confirmed that anxiety and pain before the were predictive of anxiety after the (R 2 = 0.24, F = 13.52, P <.001). P *Values are No. (%) of patients unless otherwise indicated. State anxiety was measured with the State- Trait Anxiety Inventory. Pain intensity was measured on a 10-cm visual analog scale anchored with no pain and the worst pain ever. Patient-controlled music therapy had no significant effect on state anxiety (as measured with the STAI), pain intensity, heart rate, or blood pressure, and it did not decrease the use of additional pharmacological measures to control pain and anxiety. Patients commented favorably on the use of music. Statements included comments such as: I loved the music it helped me to relax, I enjoyed listening while I had to wait on the table, and The music was very calming as I was so nervous about the. Many patients in the experimental group requested the music during sheath removal. Some patients in the control group expressed disappointment when they were not assigned to the intervention group. These patients were offered the opportunity to listen to the music tape during sheath removal. The nurses also reported that the music seemed to have a calming influence and, at times, they sought it out for patients not enrolled in the study. Although we did not find significant differences in the selected outcome measures, the intervention seemed to be enjoyed and appreciated by patients in the experimental group. Further study and validation of this point are needed. Strengths and Limitations The major strength of this study was in its design as a randomized experimental trial. The intervention was conceptually sound because it was grounded in the principles of the psychophysiological stress response and based on evidence of the effectiveness of music therapy in other clinical populations. The study did have limitations. First, the strength of the intervention, that is, CRITICALCARENURSE Vol 23, No. 2, APRIL

6 Mean heart rate, beats per minute Mean blood pressure, mm Hg Baseline Baseline After sheath insertion Figure 2 Physiological measures. Mean blood pressure was calculated as [(2 (diastolic) + systolic]/3 for indirect measurement at baseline and after the, before sheath removal. the ability of the music therapy to decrease anxiety and pain, may have been influenced by the use of existing pharmacological measures and the short duration of the intervention. Second, the selected outcome measures of pain, anxiety, and changes in heart rate and blood pressure may not have been sensitive enough to detect differences or may not have been the best measures to use. Third, we estimated the effect size on the basis of studies in hospital patients with myocardial infarctions. These patients were not undergoing an invasive acute and, consequently, are different. Control After sheath insertion Control At end of At end of Intervention Intervention After, before sheath removal After, before sheath removal Thus, our study may not have had enough power to detect a difference if a difference truly existed (ie, probability of a type I error more likely). Using our mean scores and SDs for the changes in levels of anxiety from before to after the, we did a post hoc power analysis. On the basis of this analysis, the estimated sample size required to determine a difference, with a power of 80% and an α of.05 was 240 subjects (ie, 120 per group). Future research could address these limitations. Discussion The purpose of this research was to determine the effectiveness of patient-controlled music therapy in decreasing anxiety and pain in patients undergoing coronary angiographic s for the first time. The findings indicated that patients do experience a psychophysiological response to an invasive, but no significant differences in level of anxiety, level of pain, heart rate, or blood pressure were found in patients who participated in the music therapy intervention. Before the angiographic, patients reported moderate levels of anxiety, with scores of 39 to 40 on the STAI scale. Moderate levels of anxiety have been reported in Table 3 Pearson correlation coefficients for pain and anxiety measures* Variable Anxiety before Anxiety after Pain before Anxiety before 1 Anxiety after 0.46 P<.001 Pain after Pain after 1 *State anxiety was measured with the State-Trait Anxiety Inventory. Pain intensity was measured on a 10-cm visual analog scale anchored by no pain and the worst pain ever. Significant at P < Pain before 0.31 P= P= P= P= P< CRITICALCARENURSE Vol 23, No. 2, APRIL 2003

7 patients after myocardial infarction and in conjunction with other s. After the, these levels decreased in both groups, with no significant difference in the amount of the decrease. Our findings support those reported in the literature and our assumption that having an angiographic is a stressful event for most patients. In our study, however, patients reported little pain before or after the. We measured pain at baseline, before the insertion of the sheath and catheters, and at the end of the angiographic, before the removal of the sheath. Sheath removal is a painful. 14 The timing of our measurements was such that we did not measure patients reported pain during sheath removal. This subject requires further study. Our post hoc analysis indicated that the intensity of anxiety and pain at baseline was moderately correlated with the intensity of anxiety and pain after the, whereas levels of anxiety and pain after the did not significantly correlate with each other. This result suggests that a subgroup of patients may exist who feel anxious and experience pain during angiography. Conceptually this notion makes sense. Stressors such as pain and anxiety are interactive. Before the, patients who are experiencing pain may be more anxious and patients who are more anxious may be more aware of their pain. Furthermore, we know that state anxiety is influenced by trait anxiety. We did not measure the level of trait anxiety at baseline. The nonsignificant correlations after the are not as readily explainable. However, the low levels of reported pain and anxiety after the suggest that relief associated with successful completion of an invasive is stress reducing. Further study could explore the effectiveness of music therapy in patients with higher levels of anxiety or pain at baseline, because complementary therapies may be more effective in this subgroup of patients. Patients heart rates increased and peaked at the end of the. Blood pressure increased and peaked shortly after the started, after the sheath insertion, and subsequently decreased to baseline levels. Changes in heart rate and blood pressure are predominantly controlled by the autonomic nervous system and as such are responsive to stimulation of the sympathetic nervous system when patients experience a stressful situation. Music therapy has reduced heart rate and blood pressure in other patients and conditions. 4,7,11,15 Such reductions did not occur in this study. We must note that arterial blood pressure was measured indirectly at baseline and after the, but was measured directly during the. Direct and indirect measurements do yield different arterial blood pressures, because direct methods measure pressure pulse and indirect methods measure flow. However, when mean arterial pressure is measured, as in this study, with different methods, the values are more similar. 16 Why was this intervention not effective in mediating the stress Ideally, supportive care interventions should enhance patients ability to physically and cognitively (behaviorally) cope with the stress. response for these patients? Music therapy exerts some of its therapeutic effect through distraction and diversion of attention from stressful stimuli. 8,9,17 In this study, patients ability to relax and divert their attention may have been influenced strongly by procedural events (ie, the flat table, multiple machines, and the large fluoroscope) and by an overwhelming fear and anxiety about the itself. Although patients spontaneously reported that the music was beneficial, it did not decrease the level of anxiety after the when the anxietyproducing event was over. Unfortunately, we did not determine patients perceived anxiety levels during the. In retrospect, we could have asked patients to recall their procedural experience and rate their level of procedural anxiety as has been done in other studies. 5,18 We assumed, however, that if patients were more anxious or experiencing more discomfort, a physiological response of increased heart rate and blood pressure would occur. We found no differences in heart rate and blood pressure, CRITICALCARENURSE Vol 23, No. 2, APRIL

8 measured either directly or indirectly, throughout the. Heart rate increased throughout the and then returned to baseline; blood pressure remained much the same. Patients in this study routinely received anxiolytic medication, a benzodiazepine. Benzodiazepines are used as anxiolytics, sedatives, hypnotics, and/or skeletal muscle relaxants. These drugs act at the limbic, thalamic, and hypothalamic levels of the central nervous system to produce various levels of depression of the central nervous system. Additionally, many patients received nitroglycerin for relaxation of vascular smooth muscle. These drugs alone or in combination influence peripheral vascular resistance and cardiac response and, consequently, may have mediated the effect of the music intervention. The routine use of β-adrenergic blocking agents in these patients may have mediated the sympathetic response to stress, by the action of slowing heart rate and depressing cardiac function. The dose of music may not have been strong enough to influence the psychophysiological response when pharmacological agents were used. It would be interesting to explore the effectiveness and acceptability of various doses of pharmacological and nonpharmacological methods for the reduction of anxiety in patients undergoing angiography. Finally, we selected the outcomes of pain and anxiety as the dependent variables on the basis of previous intervention studies in other conditions and our understanding of the psychophysiological response to stress. Within the context of an invasive procedural event, the patient s cognitive evaluation of the experience is also relevant. The unelicited comments by the patients and the nurses support this assumption. Thus, future studies could explore the effectiveness of music therapy on cognitive outcomes, such as satisfaction with care, particularly satisfaction with management of pain and anxiety. Conclusion In summary, patients undergoing diagnostic angiography or percutaneous intervention for the first time (1) experience moderately high levels of anxiety before the and moderate levels of anxiety after the, (2) report minimal pain before and after the, and (3) have a cardiovascular psychophysiological stress response (increased heart rate, increased blood pressure) during the. A patient-controlled music intervention had no effect on postprocedural pain and anxiety, as measured in this study. Future research could explore the effectiveness of different doses of pharmacological agents in conjunction with music therapy and the effectiveness of music therapy in patients with higher levels of anxiety and/or pain before the. When it does no harm and patients desire it, music therapy seems to be an appropriate supportive care intervention for patients undergoing invasive coronary angiographic s. Acknowledgments We acknowledge the support and contribution of the registered nurses, cardiovascular technicians, and cardiologists in Kingston General Hospital s cardiovascular laboratory and the Hotel Dieu Hospital s outpatient cardiology clinic. We also acknowledge the generous donation of audiocassette tape decks made by Medtronic of Canada Inc and Guidant Corporation. Funding for this research project was provided by the 1998 American Association of Critical-Care Nurses Sigma Theta Tau critical care grant and the Kingston General Hospital research development grant. References 1. Spielberger C. Manual for State-Trait Anxiety Inventory. Palo Alto, Calif: Consulting Psychologists Press; Elliott D. The effects of music and muscle relaxation on patient anxiety in a coronary care unit. Heart Lung. 1994;23: Bolwerk CAL. Effects of relaxing music on state anxiety in myocardial infarction patients. Crit Care Nurs Q. September 1990;13: White JM. Music therapy: an intervention to reduce anxiety in the myocardial infarction patient. Clin Nurse Spec. 1992;6: White JM. Effects of relaxing music on cardiac autonomic balance and anxiety after acute myocardial infarction. Am J Crit Care. 1999;8: Barnason S, Zimmerman L, Nieveen J. The effects of music interventions on anxiety in the patient after coronary artery bypass grafting. Heart Lung. 1995;24: Byers JF, Smyth KA. Effect of a music intervention on noise annoyance, heart rate, and blood pressure in cardiac surgery patients. Am J Crit Care. 1997;6: Magill-Levreault L. Music therapy in pain and symptom management. J Palliat Care. 1993;9: Watkins GR. Music therapy: proposed physiological mechanisms and clinical implications. Clin Nurse Spec. 1997;11: Stevens K. Patients perceptions of music during surgery. J Adv Nurs. 1990;15: Palakanis KC, DeNobile JW, Sweeney WB, Blankenship CL. Effect of music therapy on state anxiety in patients undergoing flexible sigmoidoscopy. Dis Colon Rectum. 1994;37: Good M. Effects of relaxation and music on postoperative pain: a review. J Adv Nurs. 1996;24: Melzack R. Pain Assessment and Measurement. New York, NY: Raven Press; Puntillo K, White C, Morris A, et al. Patients perceptions and responses to procedural pain: results from the Thunder II project. Am J Crit Care. 2001;10: Chlan LL. Psychophysiologic responses of mechanically ventilated patients to music: a pilot study. Am J Crit Care. 1995;4: McGhee B, Bridges ME. Monitoring arterial blood pressure: what you may not know. Crit Care Nurse. April 2002;22: Henry LL. Music therapy: a nursing intervention for the control of pain and anxiety in the ICU: a review of the research literature. Dimens Crit Care Nurs. 1995;14: Heiser RM, Chiles K, Fudge M, Gray SE. The use of music during the immediate postoperative recovery period. AORN J. 1997;65: CRITICALCARENURSE Vol 23, No. 2, APRIL 2003