Journal of Pediatric Psychology, Vol. 17, No. 1, 1992, pp. 95-109
Bruce Ambuel2 Medical College of Wisconsin
Kim W. Hamlett University of Virginia
Celeste M. Marx3 Case Western Reserve University
Jeffrey L. Blumer Case Western Reserve University Received October 23, 1990; accepted June 14, 1991
Managing psychological distress is a central treatment goal in Pediatric Intensive Care Units (PICUs), with medical and psychological implications. However, there is no objective measure for assessing efficacy of pharmacologic and psychological interventions used to reduce distress. Development of the COMFORT scale is described, a nonintrusive measure for assessing distress in P1CV patients. Eight dimensions were selected based upon a literature review and survey ofPICU nurses. Interrater agreement and internal consistency were high. •We gratefully acknowledge Suzanne L. Thompson, Margaret Morrison, and the nursing staff of Rainbow Babies and Children's Hospital's Pediatric Intensive Care Unit for assistance in data collection, Dennis Drotar, Ronald Blount, Michael Roberts, and two anonymous reviewers for this Journal for helpful comments on previous drafts of this article, Sue Bowman for her assistance in manuscript preparation, and the children who participated in this study as well as their parents. 2 A11 correspondence should be sent to Bruce Ambuel, Department of Family Medicine, Medical College of Wisconsin, Waukesha Family Practice Center, 210 N.W. Barstow Street, Waukesha, Wisconsin 53188. 'Requests for copies of the COMFORT Scale and manual should be addressed to Celeste Marx, Department of Pediatrics, Rainbow Babies and Childrens Hospital, 2101 Adelbert Road, Cleveland, Ohio 44106. 95 OI46-8693/92/0200-009SS6.50/0 © 1992 Plenum Publishing Coiporauon
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
Assessing Distress in Pediatric Intensive Care Environments: The COMFORT Scale1
96
Ambuel, Hamlett, Marx, and Blumer
Criterion validity, assessed by comparison with concurrent global ratings of PICU nurses, was also high. Principal components analysis revealed 2 correlated factors, behavioral and physiologic, accounting for 84% of variance. An ecological-developmental model is presented for further study of children's distress and coping in the PICU. KEY WORDS: distress; pain; critical care; pediatnc intensive care; developmental.
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
Critical care medicine has developed the technology and pharmacology to successfully treat children with increasingly severe illness and injury. This success has created a new clinical challenge, managing children's distress and promoting coping during hospitalization in the Pediatric Intensive Care Unit (PICU). In addition to distress associated with critical illness and injury, children hospitalized in a PICU are exposed to an environment characterized by highly variable, sometimes excessive stimulation (lights, noise and activity associated with monitors and respirators, and medical emergencies), lack of diurnal variation, new and frequently changing caregivers, and a variety of distressing or painful procedures (e.g., mechanical ventilation and arterial cannulation). These stressors may be magnified for pediatric patients who have reduced contact with family members and may be unable to comprehend events and communicate because they are preverbal or mechanically ventilated. Managing distress has clear clinical implications. For example, children in distress have a higher metabolic rate with increased demand for oxygen and calories, and may resist necessary mechanical ventilation. Therefore PICU staff routinely attempt to control distress by administering sedatives and analgesics, and/or managing the social and physical environment. However, there are no objective, standardized measures for assessing children's distress in the PICU. This has impeded the development and systematic validation of protocols for managing distress. Even routine interventions, such as administering potent sedatives and analgesics, are currently based upon subjective clinical impressions of efficacy (American Academy of Pediatrics, Committee on Drugs, 1985). We describe the development of a reliable and valid measure for assessing children's distress during hospitalization in an intensive care environment.
DISTRESS AND COPING IN PEDIATRIC INTENSIVE CARE ENVIRONMENTS Previous research documents clinically relevant levels of distress in patients hospitalized on critical care environments. Children hospitalized in PICUs experience significant distress (Rothstein, 1980), and when conscious are relatively unengaged with their environment, stare into space, and exhibit a "notable lack
Assessing Childrens' Distress in the PICU
97
DEFINING AND ASSESSING DISTRESS The concept of psychological distress has been defined in health psychology literature by Katz, Kellerman, and Siegel (1980) and Blount et al. (1989) who describe behavioral distress as encompassing all behaviors of negative affect associated with pain, anxiety, and fear. Much of the research exploring this construct has examined children's acute responses to pain. Distress, however, can exist in the absence of pain, and often does in children hospitalized in a critical care environment where signs of acute pain are aggressively managed. Our conceptualization of psychological distress builds upon and extends this earlier work by including distress in the absence of obvious pain. Psychological distress is an organism's response to aversive internal and external stimuli and may include discomfort, anxiety, fear, and, at the extreme, pain. The organisms response is multidimensional with three components: (a) behavioral (agitated movement, grimacing, crying, avoidance, etc); (b) physiologic (increased muscle tension, heart rate, blood pressure, hormonal response, etc.); and (c) phenomenologic (self-report of anxiety, fear, pain, etc).
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
of behavior," including flat affect and little verbal interaction (Cataldo, Bessman, Parker, Pearson, & Rogers, 1979). Premature or critically ill neonates hospitalized in ICUs also experience frequent distress (Gottfried & Gaiter, 1985; Johnson, Young, Young, & Helm, 1989). Retrospective studies of adult patients hospitalized in cardiac ICUs describe responses ranging from common posttraumatic distress following discharge in which patients described their experience as disturbing and frightening, and less common but extreme psychiatric delirium states during hospitalization (Bowden, 1975; Komfeld, 1971). Consistent with these studies of patient reactions, there is consensus among physicians that managing distress is an essential treatment goal on the PICU. In a survey of 45 PICU training centers (Marx, Rosenberg, Ambuel, Hamlett, Thompson, & Blumer, 1989), physicians identified management of distress and discomfort as a high priority, and reported frequent use of sedatives and analgesics. However, physicians in this same survey also reported wide variation in drug dosage and a high degree of dissatisfaction with the efficacy of pharmacologic agents. Regarding psychosocial interventions, Cataldo et al. (1979) demonstrated that involvement of a child-life professional can improve children's attention, relatedness to staff, and affect. While some PICU training centers regularly employ these and other social interventions, many do not (Marx et al., 1989), and there are few studies that systematically document efficacy. Treatment protocols employing pharmacologic, environmental, and psychosocial interventions have not been validated by research. In the absence of objective studies of efficacy, there is great potential for misuse and underuse.
98
Ambuel, Hamlett, Marx, and Blumer
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
A number of reliable and valid measures have been developed to provide observer ratings of behavioral and physiologic indices of children's distress during painful medical procedures (see Blount, Corbin, & Wolfe, 1987; Jay, Ozolins, Elliot, & Caldwell, 1983; Katz et al., 1980; LeBaron & Zeltzer, 1984). These scales are not appropriate for continuous observation of children during hospitalization on the PICU where factors producing distress are not limited to discrete events, acute pain is managed aggressively with pharmacologic interventions, and a child's ability to communicate and express distress is often physically constrained by instrumentation (e.g., placement of an endotracheal tube prevents speech, while sensors for continuous monitoring of blood pressure and heart rate limit physical movement). Two measures have been designed to assess distress and coping in hospital inpatient environments. McGrath et al. (1985) developed the Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) to assess postoperative pain in young children. Observers rate six dimensions of behavior selected based on a survey of experienced recovery room nurses. In a similar vein, Johnson et al. (1989) developed the Pain Assessment Inventory for Neonates (PAIN) to evaluate infants' behavioral and physiologic responses to routine care procedures. Both measures have high interrater reliability and validity, however neither scale is optimal for the PICU. The CHEOPS is not designed for an intensive care environment and the PAIN scale targets a neonatal population and emphasizes acute responses to painful events. Although these existing scales do not meet the specific needs for assessing distress in PICU environments, this research demonstrates that reliable and valid observational scales can be developed when custom-designed for specific environments and procedures. Our goal in this study is to design, for the PICU, a reliable and valid measure of children's distress that is nonintrusive, multidimensional, suitable for continuous observation, and includes dimensions that remain variable in the face of changing disease state. Specific study objectives are (a) identifying behavioral and physiologic dimensions for rating distress in infants and children in a PICU environment; (b) constructing an observer rating scale using these dimensions; (c) demonstrating observer agreement and validity; and (d) investigating the relationship among scale dimensions.
METHODS COMFORT Scale Development Potential scale variables were identified by reviewing behavioral science and medical literature on assessment of pediatric distress and pain, and surveying 20 experienced critical care nurses at a tertiary care children's hospital to identify variables they report using to assess patient distress. Eight physiologic and
Assessing Childrens' Distress in the PICU
99
BLOOD PRESSURE
ALERTNESS Deeply asleep
1
Lightly asleep
2
Blood pressure consistently at baseline
2
Drowsy
3
Infrequent elevations of 15% or more during observation period
3
Fully awake and alert
4
Hyperalert
5
Blood pressure below baseline
Sustained elevation of 15% or more
4
5
Fig. 1. Sample COMFORT scale dimensions (see Appendix for descriptions of other dimensions).
behavioral variables were then selected for a pilot version of the COMFORT scale because they were commonly used by clinicians, responded rapidly to changing levels of distress, could be assessed rapidly and nonintrusively, would reflect distress in children of all ages, and were likely to remain variable in the face of changes in disease state and drug treatment: mean arterial blood pressure, heart rate, muscle tone, facial tension, alertness, calmness/agitation, respiratory behavior, and physical movement. A five-point behaviorally anchored, interval rating scale was designed for each variable with a total COMFORT score obtained by summing scores for all eight variables. This measure was pilot tested, then revised to clarify the verbal descriptions of each variable. Figure 1 illustrates the rating scales for alertness and mean arterial blood pressure; other variables are described in the Appendix. Participants Participants were children, without age restriction, hospitalized on the PICU of a tertiary care children's hospital, receiving intermittent mandatory ventilation or continuous positive airway pressure, with vital signs monitored via
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
Frequent elevations of 15% or more above baseline (more than 3 during observation period)
1
100
Ambuel, Hamlett, Marx, and Blumer
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
arterial line and cardiorespiratory monitor and displayed on bedside monitors. Excluded were patients who had seriously compromised neurological status (head injury, ischemic encephalopathy, stroke, status epilepticus), profound mental retardation, recent multiple trauma (within 72 hours), or altered muscle tone or contractures. Patients were also excluded temporarily if experiencing severe, acute pain as judged by self-report or the opinion of the managing nurse or attending physician. Although children in severe, acute pain are certainly experiencing distress, acute pain is managed immediately and aggressively in pediatric intensive care units. The goal of this study is, therefore, to develop a measure sensitive to subtle signs of distress rather than infrequent and momentary acute episodes of pain. Consecutive admissions to the PICU, who met these selection criteria, were enrolled contingent upon availability of trained raters. There were 37 participants; each patient was observed on one to two occasions, generating a total of 50 observations. Participants' age ranged from newborn to 204 months (M = 37.1; SD = 52.7), and included 28 infants (newborn to 23 months), 17 preschool children (24 to 71 months), 2 primary school children (72 to 143 months), and 3 adolescents (S144 months). Participants were 17 males and 20 females and a population representative racial mix (24 white; 12 African/American; 1 Hispanic) with the following principal diagnoses: cardiac disease (18), respiratory disease (13), infectious disease (3), neurological disorders (2), and, status post trauma (1). Measures Patient distress was assessed using the COMFORT Scale, and a visual analog scale (VAS), a 10-cm horizontal line on a single piece of paper with end points anchored by the descriptions "absolutely calm," and "extremely distressed" (Jay, 1988; Nyren, 1988). Observers using the VAS were instructed to make a single mark at the point on the line which describes how distressed the child was during observation. Procedures To assess observer agreement and validity, each participant was observed concurrently by three raters, a principal investigator, a research assistant trained in use of the COMFORT scale, and an experienced intensive care nurse who was unfamiliar with the COMFORT scale and had not been caring for the participant. The principal investigator completed the COMFORT scale and VAS (in counterbalanced order across patients), the research assistant completed the COMFORT scale and the clinical nurse completed the VAS.
Assessing Childrens' Distress in the PICU
101
Analysis Interrater agreement for individual variables and total COMFORT score was assessed by calculating Pearson correlations of the two observers. Scale and item attributes were examined using test analysis, including internal consistency and item-total correlation. Clinical validity was examined by calculating the Pearson correlation coefficient between total COMFORT score (averaged across raters) and the clinical judgment of trained nurses as indicated on the VAS. Relationships among variables on the COMFORT scale were examined by first averaging ratings of each observer for each variable, then using correlation analysis. Finally, principal components analysis was used in an exploratory fashion to examine dimensionality of the scale. RESULTS Descriptive Statistics Table I shows the mean, range, and standard deviation of the total COMFORT score and eight variables of the scale (averaged across raters). The eight behaviorally anchored rating scales have desirable measurement properties.
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
The two raters who completed the COMFORT scale reviewed the participant's bedside flow sheet of vital signs and treatments prior to observation, then agreed on baseline levels for heart rate and blood pressure. This was the only discussion between the raters. These raters then observed the patient for 2 minutes. Muscle tone was assessed at the.end of the 2-minute observation by supporting the upper arm or thigh of the participant and gently flexing and extending the limb. Raters then independently completed COMFORT scales. The clinical nurse observed the patient for this same period, assessed the patient's level of distress as they would routinely do for their own patient, then independently rated distress on the VAS. Clinical nurse raters were blind to the COMFORT scale variables and format and to baselines established for heart rate and blood pressure. They would be aware that the other raters were observing patient flow sheets for trends as well as assessing muscle tension. This, in itself, should not introduce a strong bias because our initial survey of clinical nurses indicated that nurses routinely observe these variables when assessing distress. Patient distress was routinely assessed as part of standard care provided on this PICU using observation procedures similar to those employed in this study. The research procedures merely quantified observations that were conducted routinely throughout the day during a patient's hospitalization. Proxy consent for participation in this study was, therefore, provided by the institution.
102
Ambuel, Hamlett, Marx, and Blunter Table I. Descriptive Statistics for Total COMFORT Score and Eight Scale Dimensions
Alertness Calmness Respiratory response Movement Mean arterial pressure Heart rate Muscle tone Facial expression COMFORT total
M
SD
2.8 1.9 2.5 2.7 2.4 2.5 3.0 2.4
0.9 0.9 0.8 1.1 0.8 0.9 0.7 0.8
1.0 1.0 1.0 1.0 1.5 1.5 1.5 1.0
4.5 4.0 5.0 5.0 5.0 5.0 4.0 5.0
20.2
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
Dimension
Minimum
5.3
12.0
34.5
Maximum
Trained raters used nearly the complete range for each variable as well as the total COMFORT score, and means for the eight variables fell near the midpoint (from 1.9 to 3.0). This indicates that the rating scale for each variable has been constructed to allow scoring of extreme values and avoid ceiling or floor effects. Rater Agreement and Scale Validity Rater agreement is demonstrated by the high interrater correlation for total COMFORT score, r = .84; n = 50; p < .01 (see Table II & Figure 2). As expected, individual scale dimensions have lower but significant correlations (r
Table II. Interrater Agreement, Internal Consistency, and Item Analysis for Eight Dimensions and Total COMFORT Score Dimension
Observer agreement"
Alertness Calmness Respiratory response Movement Mean arterial pressure Heart rate Muscle tone Facial expression
.73 .69 .70 .75 .51 .66 .52 .51
COMFORT
.84
Item-total correlation"*
Alpha""
.70 .90 .73 .80 .66 .60 .30 .81
.88 .86 .88 .87 .88 .89 .91 .87
—
.90
"Pearson correlation coefficients; critical values (n = 50) are .28 for p < .05, and .36 forp < .01. *Correlationn for each item with total COMFORT score excluding this item.
Bruce Ambuel2 Medical College of Wisconsin
Kim W. Hamlett University of Virginia
Celeste M. Marx3 Case Western Reserve University
Jeffrey L. Blumer Case Western Reserve University Received October 23, 1990; accepted June 14, 1991
Managing psychological distress is a central treatment goal in Pediatric Intensive Care Units (PICUs), with medical and psychological implications. However, there is no objective measure for assessing efficacy of pharmacologic and psychological interventions used to reduce distress. Development of the COMFORT scale is described, a nonintrusive measure for assessing distress in P1CV patients. Eight dimensions were selected based upon a literature review and survey ofPICU nurses. Interrater agreement and internal consistency were high. •We gratefully acknowledge Suzanne L. Thompson, Margaret Morrison, and the nursing staff of Rainbow Babies and Children's Hospital's Pediatric Intensive Care Unit for assistance in data collection, Dennis Drotar, Ronald Blount, Michael Roberts, and two anonymous reviewers for this Journal for helpful comments on previous drafts of this article, Sue Bowman for her assistance in manuscript preparation, and the children who participated in this study as well as their parents. 2 A11 correspondence should be sent to Bruce Ambuel, Department of Family Medicine, Medical College of Wisconsin, Waukesha Family Practice Center, 210 N.W. Barstow Street, Waukesha, Wisconsin 53188. 'Requests for copies of the COMFORT Scale and manual should be addressed to Celeste Marx, Department of Pediatrics, Rainbow Babies and Childrens Hospital, 2101 Adelbert Road, Cleveland, Ohio 44106. 95 OI46-8693/92/0200-009SS6.50/0 © 1992 Plenum Publishing Coiporauon
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
Assessing Distress in Pediatric Intensive Care Environments: The COMFORT Scale1
96
Ambuel, Hamlett, Marx, and Blumer
Criterion validity, assessed by comparison with concurrent global ratings of PICU nurses, was also high. Principal components analysis revealed 2 correlated factors, behavioral and physiologic, accounting for 84% of variance. An ecological-developmental model is presented for further study of children's distress and coping in the PICU. KEY WORDS: distress; pain; critical care; pediatnc intensive care; developmental.
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
Critical care medicine has developed the technology and pharmacology to successfully treat children with increasingly severe illness and injury. This success has created a new clinical challenge, managing children's distress and promoting coping during hospitalization in the Pediatric Intensive Care Unit (PICU). In addition to distress associated with critical illness and injury, children hospitalized in a PICU are exposed to an environment characterized by highly variable, sometimes excessive stimulation (lights, noise and activity associated with monitors and respirators, and medical emergencies), lack of diurnal variation, new and frequently changing caregivers, and a variety of distressing or painful procedures (e.g., mechanical ventilation and arterial cannulation). These stressors may be magnified for pediatric patients who have reduced contact with family members and may be unable to comprehend events and communicate because they are preverbal or mechanically ventilated. Managing distress has clear clinical implications. For example, children in distress have a higher metabolic rate with increased demand for oxygen and calories, and may resist necessary mechanical ventilation. Therefore PICU staff routinely attempt to control distress by administering sedatives and analgesics, and/or managing the social and physical environment. However, there are no objective, standardized measures for assessing children's distress in the PICU. This has impeded the development and systematic validation of protocols for managing distress. Even routine interventions, such as administering potent sedatives and analgesics, are currently based upon subjective clinical impressions of efficacy (American Academy of Pediatrics, Committee on Drugs, 1985). We describe the development of a reliable and valid measure for assessing children's distress during hospitalization in an intensive care environment.
DISTRESS AND COPING IN PEDIATRIC INTENSIVE CARE ENVIRONMENTS Previous research documents clinically relevant levels of distress in patients hospitalized on critical care environments. Children hospitalized in PICUs experience significant distress (Rothstein, 1980), and when conscious are relatively unengaged with their environment, stare into space, and exhibit a "notable lack
Assessing Childrens' Distress in the PICU
97
DEFINING AND ASSESSING DISTRESS The concept of psychological distress has been defined in health psychology literature by Katz, Kellerman, and Siegel (1980) and Blount et al. (1989) who describe behavioral distress as encompassing all behaviors of negative affect associated with pain, anxiety, and fear. Much of the research exploring this construct has examined children's acute responses to pain. Distress, however, can exist in the absence of pain, and often does in children hospitalized in a critical care environment where signs of acute pain are aggressively managed. Our conceptualization of psychological distress builds upon and extends this earlier work by including distress in the absence of obvious pain. Psychological distress is an organism's response to aversive internal and external stimuli and may include discomfort, anxiety, fear, and, at the extreme, pain. The organisms response is multidimensional with three components: (a) behavioral (agitated movement, grimacing, crying, avoidance, etc); (b) physiologic (increased muscle tension, heart rate, blood pressure, hormonal response, etc.); and (c) phenomenologic (self-report of anxiety, fear, pain, etc).
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
of behavior," including flat affect and little verbal interaction (Cataldo, Bessman, Parker, Pearson, & Rogers, 1979). Premature or critically ill neonates hospitalized in ICUs also experience frequent distress (Gottfried & Gaiter, 1985; Johnson, Young, Young, & Helm, 1989). Retrospective studies of adult patients hospitalized in cardiac ICUs describe responses ranging from common posttraumatic distress following discharge in which patients described their experience as disturbing and frightening, and less common but extreme psychiatric delirium states during hospitalization (Bowden, 1975; Komfeld, 1971). Consistent with these studies of patient reactions, there is consensus among physicians that managing distress is an essential treatment goal on the PICU. In a survey of 45 PICU training centers (Marx, Rosenberg, Ambuel, Hamlett, Thompson, & Blumer, 1989), physicians identified management of distress and discomfort as a high priority, and reported frequent use of sedatives and analgesics. However, physicians in this same survey also reported wide variation in drug dosage and a high degree of dissatisfaction with the efficacy of pharmacologic agents. Regarding psychosocial interventions, Cataldo et al. (1979) demonstrated that involvement of a child-life professional can improve children's attention, relatedness to staff, and affect. While some PICU training centers regularly employ these and other social interventions, many do not (Marx et al., 1989), and there are few studies that systematically document efficacy. Treatment protocols employing pharmacologic, environmental, and psychosocial interventions have not been validated by research. In the absence of objective studies of efficacy, there is great potential for misuse and underuse.
98
Ambuel, Hamlett, Marx, and Blumer
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
A number of reliable and valid measures have been developed to provide observer ratings of behavioral and physiologic indices of children's distress during painful medical procedures (see Blount, Corbin, & Wolfe, 1987; Jay, Ozolins, Elliot, & Caldwell, 1983; Katz et al., 1980; LeBaron & Zeltzer, 1984). These scales are not appropriate for continuous observation of children during hospitalization on the PICU where factors producing distress are not limited to discrete events, acute pain is managed aggressively with pharmacologic interventions, and a child's ability to communicate and express distress is often physically constrained by instrumentation (e.g., placement of an endotracheal tube prevents speech, while sensors for continuous monitoring of blood pressure and heart rate limit physical movement). Two measures have been designed to assess distress and coping in hospital inpatient environments. McGrath et al. (1985) developed the Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) to assess postoperative pain in young children. Observers rate six dimensions of behavior selected based on a survey of experienced recovery room nurses. In a similar vein, Johnson et al. (1989) developed the Pain Assessment Inventory for Neonates (PAIN) to evaluate infants' behavioral and physiologic responses to routine care procedures. Both measures have high interrater reliability and validity, however neither scale is optimal for the PICU. The CHEOPS is not designed for an intensive care environment and the PAIN scale targets a neonatal population and emphasizes acute responses to painful events. Although these existing scales do not meet the specific needs for assessing distress in PICU environments, this research demonstrates that reliable and valid observational scales can be developed when custom-designed for specific environments and procedures. Our goal in this study is to design, for the PICU, a reliable and valid measure of children's distress that is nonintrusive, multidimensional, suitable for continuous observation, and includes dimensions that remain variable in the face of changing disease state. Specific study objectives are (a) identifying behavioral and physiologic dimensions for rating distress in infants and children in a PICU environment; (b) constructing an observer rating scale using these dimensions; (c) demonstrating observer agreement and validity; and (d) investigating the relationship among scale dimensions.
METHODS COMFORT Scale Development Potential scale variables were identified by reviewing behavioral science and medical literature on assessment of pediatric distress and pain, and surveying 20 experienced critical care nurses at a tertiary care children's hospital to identify variables they report using to assess patient distress. Eight physiologic and
Assessing Childrens' Distress in the PICU
99
BLOOD PRESSURE
ALERTNESS Deeply asleep
1
Lightly asleep
2
Blood pressure consistently at baseline
2
Drowsy
3
Infrequent elevations of 15% or more during observation period
3
Fully awake and alert
4
Hyperalert
5
Blood pressure below baseline
Sustained elevation of 15% or more
4
5
Fig. 1. Sample COMFORT scale dimensions (see Appendix for descriptions of other dimensions).
behavioral variables were then selected for a pilot version of the COMFORT scale because they were commonly used by clinicians, responded rapidly to changing levels of distress, could be assessed rapidly and nonintrusively, would reflect distress in children of all ages, and were likely to remain variable in the face of changes in disease state and drug treatment: mean arterial blood pressure, heart rate, muscle tone, facial tension, alertness, calmness/agitation, respiratory behavior, and physical movement. A five-point behaviorally anchored, interval rating scale was designed for each variable with a total COMFORT score obtained by summing scores for all eight variables. This measure was pilot tested, then revised to clarify the verbal descriptions of each variable. Figure 1 illustrates the rating scales for alertness and mean arterial blood pressure; other variables are described in the Appendix. Participants Participants were children, without age restriction, hospitalized on the PICU of a tertiary care children's hospital, receiving intermittent mandatory ventilation or continuous positive airway pressure, with vital signs monitored via
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
Frequent elevations of 15% or more above baseline (more than 3 during observation period)
1
100
Ambuel, Hamlett, Marx, and Blumer
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
arterial line and cardiorespiratory monitor and displayed on bedside monitors. Excluded were patients who had seriously compromised neurological status (head injury, ischemic encephalopathy, stroke, status epilepticus), profound mental retardation, recent multiple trauma (within 72 hours), or altered muscle tone or contractures. Patients were also excluded temporarily if experiencing severe, acute pain as judged by self-report or the opinion of the managing nurse or attending physician. Although children in severe, acute pain are certainly experiencing distress, acute pain is managed immediately and aggressively in pediatric intensive care units. The goal of this study is, therefore, to develop a measure sensitive to subtle signs of distress rather than infrequent and momentary acute episodes of pain. Consecutive admissions to the PICU, who met these selection criteria, were enrolled contingent upon availability of trained raters. There were 37 participants; each patient was observed on one to two occasions, generating a total of 50 observations. Participants' age ranged from newborn to 204 months (M = 37.1; SD = 52.7), and included 28 infants (newborn to 23 months), 17 preschool children (24 to 71 months), 2 primary school children (72 to 143 months), and 3 adolescents (S144 months). Participants were 17 males and 20 females and a population representative racial mix (24 white; 12 African/American; 1 Hispanic) with the following principal diagnoses: cardiac disease (18), respiratory disease (13), infectious disease (3), neurological disorders (2), and, status post trauma (1). Measures Patient distress was assessed using the COMFORT Scale, and a visual analog scale (VAS), a 10-cm horizontal line on a single piece of paper with end points anchored by the descriptions "absolutely calm," and "extremely distressed" (Jay, 1988; Nyren, 1988). Observers using the VAS were instructed to make a single mark at the point on the line which describes how distressed the child was during observation. Procedures To assess observer agreement and validity, each participant was observed concurrently by three raters, a principal investigator, a research assistant trained in use of the COMFORT scale, and an experienced intensive care nurse who was unfamiliar with the COMFORT scale and had not been caring for the participant. The principal investigator completed the COMFORT scale and VAS (in counterbalanced order across patients), the research assistant completed the COMFORT scale and the clinical nurse completed the VAS.
Assessing Childrens' Distress in the PICU
101
Analysis Interrater agreement for individual variables and total COMFORT score was assessed by calculating Pearson correlations of the two observers. Scale and item attributes were examined using test analysis, including internal consistency and item-total correlation. Clinical validity was examined by calculating the Pearson correlation coefficient between total COMFORT score (averaged across raters) and the clinical judgment of trained nurses as indicated on the VAS. Relationships among variables on the COMFORT scale were examined by first averaging ratings of each observer for each variable, then using correlation analysis. Finally, principal components analysis was used in an exploratory fashion to examine dimensionality of the scale. RESULTS Descriptive Statistics Table I shows the mean, range, and standard deviation of the total COMFORT score and eight variables of the scale (averaged across raters). The eight behaviorally anchored rating scales have desirable measurement properties.
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
The two raters who completed the COMFORT scale reviewed the participant's bedside flow sheet of vital signs and treatments prior to observation, then agreed on baseline levels for heart rate and blood pressure. This was the only discussion between the raters. These raters then observed the patient for 2 minutes. Muscle tone was assessed at the.end of the 2-minute observation by supporting the upper arm or thigh of the participant and gently flexing and extending the limb. Raters then independently completed COMFORT scales. The clinical nurse observed the patient for this same period, assessed the patient's level of distress as they would routinely do for their own patient, then independently rated distress on the VAS. Clinical nurse raters were blind to the COMFORT scale variables and format and to baselines established for heart rate and blood pressure. They would be aware that the other raters were observing patient flow sheets for trends as well as assessing muscle tension. This, in itself, should not introduce a strong bias because our initial survey of clinical nurses indicated that nurses routinely observe these variables when assessing distress. Patient distress was routinely assessed as part of standard care provided on this PICU using observation procedures similar to those employed in this study. The research procedures merely quantified observations that were conducted routinely throughout the day during a patient's hospitalization. Proxy consent for participation in this study was, therefore, provided by the institution.
102
Ambuel, Hamlett, Marx, and Blunter Table I. Descriptive Statistics for Total COMFORT Score and Eight Scale Dimensions
Alertness Calmness Respiratory response Movement Mean arterial pressure Heart rate Muscle tone Facial expression COMFORT total
M
SD
2.8 1.9 2.5 2.7 2.4 2.5 3.0 2.4
0.9 0.9 0.8 1.1 0.8 0.9 0.7 0.8
1.0 1.0 1.0 1.0 1.5 1.5 1.5 1.0
4.5 4.0 5.0 5.0 5.0 5.0 4.0 5.0
20.2
Downloaded from http://jpepsy.oxfordjournals.org/ at York University Libraries on June 17, 2014
Dimension
Minimum
5.3
12.0
34.5
Maximum
Trained raters used nearly the complete range for each variable as well as the total COMFORT score, and means for the eight variables fell near the midpoint (from 1.9 to 3.0). This indicates that the rating scale for each variable has been constructed to allow scoring of extreme values and avoid ceiling or floor effects. Rater Agreement and Scale Validity Rater agreement is demonstrated by the high interrater correlation for total COMFORT score, r = .84; n = 50; p < .01 (see Table II & Figure 2). As expected, individual scale dimensions have lower but significant correlations (r
Table II. Interrater Agreement, Internal Consistency, and Item Analysis for Eight Dimensions and Total COMFORT Score Dimension
Observer agreement"
Alertness Calmness Respiratory response Movement Mean arterial pressure Heart rate Muscle tone Facial expression
.73 .69 .70 .75 .51 .66 .52 .51
COMFORT
.84
Item-total correlation"*
Alpha""
.70 .90 .73 .80 .66 .60 .30 .81
.88 .86 .88 .87 .88 .89 .91 .87
—
.90
"Pearson correlation coefficients; critical values (n = 50) are .28 for p < .05, and .36 forp < .01. *Correlationn for each item with total COMFORT score excluding this item.
