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Journal of Neuroscience Nursing:
doi: 10.1097/JNN.0b013e318214570f
Article: ONLINE ONLY

Sitting Without Back Support Position for Prolonged Consciousness Disturbance Patients: An Intervention Program Case Study

Okubo, Nobuko

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Author Information

Questions or comments about this article may be directed to Nobuko Okubo, PhD RN, at nobu-okubo@slcn.ac.jp. She is an associate professor of Fundamental Nursing at St. Luke's College of Nursing, Tokyo, Japan.

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Abstract

ABSTRACT: The purpose of this research was to document and compare the before and after levels of consciousness of patients with prolonged consciousness disturbance (PCD) who sat for a specified length of time in a specially designed backless chair (Suwarou-Kun). Three patients were selected as participants using the PCD criteria described by Jennet and Plum in 1972. The Kohnan Vegetative Score (henceforth referred to as the Kohnan PCD Scale) and electroencephalography (EEG) measurements, together with direct observation of subtle changes, were used to record each participant's overt behavior and autonomic responses. A single-case observation/intervention time series design was used in this study. Length of exposure to the intervention and mean exposure time per session were as follows: case 1, 65 days and 30 minutes; case 2, 36 days and 11 minutes; and case 3, 43 days and 36 minutes. The Wilcoxon's rank sum test was used to analyze the pair of Kohnan PCD Scale and EEG scores collected before and at the midway point of each intervention session. Because more than two variables were being measured, the data were reanalyzed using repeated-measure analysis of variance. In cases 2 and 3, there were significant differences in the Kohnan PCD Scale and EEG scores during the "sitting without back support position" (SB) intervention period as well as at the midway point of each session (p < .05) compared with the measurements taken before the intervention. In all three cases, there also were subtle changes during the intervention, for example, eye movement, finger or thumb movement, strength of voice, and salivation. Alpha and beta waves were greater after the introduction of the SB intervention and preceded the behavioral response changes. The SB intervention resulted in at least some improvement in the level of consciousness for each participant. It remains an open question, however, whether longer exposure would have brought about further change. The SB intervention is costly in terms of human time and effort, and its beneficial effects beyond those measured in this study will require additional research.

In Japan, there are nearly 35,000 patients who have prolonged consciousness disturbance (PCD), often referred to as a vegetative state. A person has PCD when he or she exhibits a sleep-wake cycle and can respond on a reflex level but there is no cognitive functioning (Andrews, 1992; Jennet & Plum, 1972) for more than 3 months after brain injury (Suzuki & Kodama, 1976). Generally, when PCD continues for more than 3 months, the possibility of recovering from this state is extremely low, although it is possible (Howard & Miller, 1995). Only 3% of such patients emerging from PCD have lived for more than 3 years (Higashi, Yamagami, Kimura, Minouchi, & Hanada, 1993).

Rehabilitation and sensory stimulation should be made available after the patient stabilizes. However, the efficacy of sensory stimulation programs remains unclear (Howard & Miller, 1995). Lombardi et al. (2002) conducted a Cochrane review from 1966 to January 2002 and found only three controlled studies, which were inconclusive due to methodological weaknesses. Even so, nurses have explored interventions to improve levels of consciousness in their patients (Maruki, 2001). Unfortunately, the majority of PCD patients receive active therapy based only on what nurses or family members are able to provide (Tolle & Reimer, 2003). Often, interventions for patients are determined by the availability of these interventions and not on research-based practices.

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Background

Tolle and Reimer (2003) noted that nurses have incorporated multisensory stimulation into their nursing care for PCD patients, but the effectiveness of the interventions has not been subjected to controlled studies. However, many nurses believe that PCD patients may be able to process information at some level if provided with an effective external source of stimulation (Tolle & Reimer, 2003). There are several approaches to stimulation therapy. One is designed to enhance synaptic reinnervation and stimulate the reticular activating system by providing multisensory experiences. Another focuses on "information processing and mediation of reaction to sensory information with emphasis on enhancing selective attention by regulating the environment rather than providing high degrees of stimulation" (Tolle & Reimer, 2003, p. 20).

During the past 20 years, a number of Japanese nurse researchers have described the positive influence of consciousness-stimulating interventions, giving rise to the possibility that such nursing strategies can yield at least some minimal changes in consciousness. These strategies include touching (Akizuki, Mukai, & Ozawa, 1996) and stimulation of the five senses (Hirano, Hirata, Tsuchida, & Hirai, 2008; Nishimura, Ono, Yamada, Shimizu, & Komatsu, 2007). For the most part, these studies were anecdotal or descriptive in nature, with the results indicating that various types of neurological stimulation might have a positive effect on patient consciousness.

They are also involved in the discovery of new interventions for patients with PCD and in the examination of the long-term benefits. One of the novel strategies for stimulating consciousness was proposed by Kamiya, Shiro, and Hayashi (1993) and Kawashima, Hiramatsu, Taki, and Murota (1991). They partnered with a hospital bed manufacturing company and a hospital to design a backless chair so that a patient's sitting position was as close as possible to the orthostatic position most favorable for exciting the cerebral cortex (Kamiya et al., 1993; Kawashima, Hiramatsu, Taki, & Murota, 1991). To minimize back support, the patient sits on the edge of the bed in a posture where the natural sigmoid curve of the spinal column is retained by extending the dorsal muscle with the soles of the patient's feet firmly on the floor (Kawashima et al., 1991). Some nurses advocate letting patients with PCD sit without back support in a specially designed chair (Figure 1) as a means of providing neurological stimulation (Hiramatsu, 1998; Okubo, 2001). Nurses have also incorporated this particular intervention into their nursing care of patients with senile dementia or other conditions with varying degrees of disturbed consciousness (Kamiya et al., 1993; Kawashima, Hiramatsu, & Ohyoshi, 1993).

Figure 1
Figure 1
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A study that examined the effect of "sitting without back support position" (SB) on the autonomic nervous systems of healthy volunteers was conducted (Okubo & Hishinuma, 1998). Using coarse-graining spectral analysis to capture the very low frequency levels, it was shown that sitting without neck support, compared with a flat supine position, increased the function of the sympathetic nervous system, thereby stimulating the autonomic nervous system. Figure 2 depicts the relationships of the autonomic events after the stimulation provided by sitting on the backless chair. Introducing the SB intervention activates a midbrain reflex and the autonomic nervous system. In particular, sympathetic nervous system activity increases. Stimulation of the midbrain transfers to the brainstem reticular formation and also to the cerebral cortex, with increased alpha and beta brain waves expressing a more active brain. Activating the autonomic nervous system increases the blood flow in the brain, thereby supplying more oxygen to brain cells. By stimulating the cerebral cortex and promoting an increased supply of oxygen to brain cells, it may be possible to improve an individual's consciousness level. Although anecdotal reports and descriptive case studies suggested that SB provides significant brain stimulation (Hiramatsu, 1998; Okubo, 2001), there were no clinical intervention studies available. The purpose of this study, therefore, was to explore the benefits of SB over time on PCD patients by comparing levels of consciousness and electroencephalography (EEG) measurements before and after sitting a specified length of time using the SB intervention.

Figure 2
Figure 2
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Methods

Research Questions

* Will a participant with PCD who is placed on a backless chair on a regular basis have significantly lower Kohnan Vegetative Scores (henceforth referred to as the Kohnan PCD Scale) after using the backless chair than before beginning its use?

* Will a participant with PCD who is placed on a backless chair on a regular basis have significantly more active EEG measurements after using the backless chair than before beginning its use?

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Design

A single-case observation/intervention time series design (Kazdin, 1982) directed the data collection from the three participants before and during the SB intervention. Each participant served as his or her own control, providing data for the three single-case studies. The design consisted of an observational baseline period of 2 weeks and an intervention phase of approximately 1 to 2 months. Earlier researchers in this field noted the importance of gathering intervention data for at least 1 month (Higashi et al., 1993). Participants were evaluated using the same observation and intervention protocol. Observational baseline data were collected from each participant twice a day from 9 to 11 a.m. and again from 1 to 3 p.m. every other day for 2 weeks (6 days a week) for a total of 24 observations for each participant. During those times, brain waves were measured, the level of consciousness was observed, and behaviors were documented.

After the baseline period, the SB intervention was introduced twice a day, 6 days a week. Throughout the intervention period, the Kohnan PCD Scale, EEG scores, and subtle behaviors were documented four times a day: before and at the midway point of each SB session in the morning between 9 and 11 a.m. and again in the afternoon between 1 and 3 p.m. The specific timing of data collection was based on previous research conducted with PCD patients (Honma, Honma, & Hiro, 1989; Okubo, Nojima, Hayashi, Takeuchi, & Semine, 2008). Patients continued to participate in the study until they were discharged from the hospital. Table 1 includes information on the specific intervention duration for each participant.

Table 1
Table 1
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Participants

Three participants from the same hospital met the criteria of PCD according to the six standard criteria (Jennett & Plum, 1972). For each of these patients, the causative disease was an intracerebral or subarachnoid hemorrhage. Nursing care, medical care, and rehabilitation therapy provided in the hospital for the participants remained the same throughout the study. All three participants received nasogastric tube feedings and joint exercises three times a week and were eligible for discharge either to home or to a nursing home facility (Table 1).

Case 1 was a 54-year-old woman who had subarachnoid hemorrhage. The surgeon clipped the ruptured superior cerebellar artery aneurysms and inserted a ventricular-peritoneal shunt. The patient was in a complete vegetative state, and her mean Kohnan PCD Scale score was 67. The participant's mean EEG scores were as follows: delta, 51; theta, 11; alpha, 0; and beta, 0. Her length of hospitalization was 10 months at the time of study entry.

Case 2 was a 78-year-old woman who had both a subarachnoid and an intracerebral hemorrhage. The surgeon clipped a middle cerebral aneurysm, performed a right temporal lobe lobectomy, and inserted a ventricular-peritoneal shunt. This patient also had Mallory-Weiss syndrome characterized by mucosal tears at the esophagogastric junction. She was in a complete vegetative state, with a mean Kohnan PCD Scale score of 63. Her mean EEG scores were as follows: delta, 58; theta, 5; alpha, 0; and beta, 0. She had a 4-month period of hospitalization at the point of her study entry. Unfortunately, we could not measure this particular participant's EEG at the midway point of each SB intervention session because of vomiting due to Mallory-Weiss syndrome.

Case 3 was a 55-year-old man who had intracerebral hemorrhage. The surgeon evacuated an intracerebral hematoma, after which the patient was in a complete vegetative state. His mean Kohnan PCD Scale score was 67, and his mean EEG scores were as follows: delta, 59; theta, 15; alpha, 0; and beta, 0. The length of hospitalization for this patient was 5 months at the time of his study entry.

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Intervention

The SB intervention consists of sitting on a specially designed backless chair for approximately 30 minutes at a time (Figure 1). The SB chair minimizes back support because the patient sits on the chair at the edge of the patient's bed in a posture where the natural sigmoid curve of the spinal column is retained by extending the dorsal muscles with the soles of the patient's feet firmly on the floor. The SB chair is wheeled across the bed to maximize ease of transfer from the bed to the chair. Because patients with PCD sitting on the chair naturally slump forward slightly, there is a safety harness that secures the participant into the chair and holds him or her into the desired position and prevents the patient from falling too far forward.

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Measures and Instruments

Two measures were used to record the participant's overt behavior and autonomic responses. In addition, subtle behavior before the intervention and during its implementation was observed and anecdotally noted. Generally known as the Kohnan Vegetative Score, the Kohnan PCD Scale was developed in Japan based on the Jennett and Plum (1972) criteria. It is a seven-dimension behavior observation guide designed for evaluating PCD and includes more subtle response scoring than does the Glasgow Coma Scale (Fujiwara et al., 1997). The seven dimensions consist of voluntary movement, voluntary ingestion, fecal and urinary incontinence, ophthalmography and visual recognition, vocalizing and utterances, response and comprehension, and change of expression. The subscores for each of the seven dimensions of overt patient behavior are rated from 10 to 0 according to the presence or absence of those specified desired behaviors: 10 = extreme, 9 = severe, 8-7 = moderate, 5 = mild, and 0 = slight. The subscores are added to provide a total score that ranges from worst (70) to best (0). The higher the score, the more extreme the PCD condition is. Fujiwara and his colleagues were able to verify interrater and test-retest reliability as well as criterion-related validity. The interclass correlation coefficient's estimate for the summary score was .90 (95% confidence interval, 0.766-0.970); the variance of rater effect was 0.766-0.970; and the unidimentionality of the first factor comprising the scale was 91.5%. It was noted that this scale had greater interrater reliability for PCD patients in the moderate to severe category than for mildly impaired patients (Fujiwara et al., 1997).

Dimensions of frequency and amplitude of beta (14-35 Hz), alpha (8-13 Hz), theta (4-7 Hz), and delta (1-3 Hz) brain waves (Ohkuma, 1999) were measured by EEG using Neuropack Sigma (MEB-5504, Nihon Kohden, Tokyo). Each EEG was taken using two channels (C3-A1: left parietal region/left ear lobe; and C4-A2: right parietal region/right ear lobe). Five electrodes were placed on the participant's head. The high-speed mathematical computation software, Fast Fourier Transform, converted the signals received as a function of time into a frequency spectrum so that the EEG was displayed as a power spectrum analysis (Mander et al., 2010). With the use of similar techniques employed by Youhashi and Fujiwara (1996), the EEG was analyzed using a 1-minute segment bounded by low and high filtering.

Finally, our research team transformed the EEG data into an EEG score that could be subjected to statistical analysis. Because the EEG power spectral heights in this study were the same as the degree of power (Nihon Kodensha Co., Ltd., 1993), it was calculated as follows: A small wave (1-4.9 mm) equaled a score of 1; a medium wave (5-14.9 mm) or two small waves equaled a score of 2; and a large wave (≥15 mm) or two or more medium waves equaled a score of 3. Scores were added together within the 1-minute segment. The resultant total is henceforth referred to as the EEG score. The EEG scores ranged from a low of 0 to a high of 18 for beta waves, 0 to 49 for alpha waves, 0 to 58 for theta waves, and 27 to 64 for delta waves. The higher the score for each kind of brain wave, especially the beta and alpha waves, the greater the participant's brain activity is. Subtle behavior changes based on anecdotal observations were included because the Kohnan PCD Scale was not designed to measure behavior such as the slight movement of a finger. An assessment of these more subtle behaviors also was sought to increase the sensitivity of our overall understanding of the SB intervention.

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Intervention Protocol

One researcher provided the SB intervention for all three participants and also collected the data. She received 4 days of advanced training at the Kohnan Hospital from Dr. Fujiwara in the Kohnan PCD Scale scoring technique, after which interrater reliability between the researcher and Kohnan Hospital clinical nurses was 90%. To ensure quality and consistency using the intervention protocol, she also spent 3 weeks practicing the SB procedure so that the movement and transfer of patients went smoothly and safely and the Kohnan PCD Scale scoring was performed competently. Training for EEG was completed during a 2-week period, in which use of the SB intervention, Kohnan PCD Scale scoring, and application of the EEG were practiced and integrated together. In addition, case 3 was selected during the SB intervention period to assess interrater reliability between the researcher and the clinical nurses, which turned out to be 93%.

Given each participant's physical vulnerability, a strict protocol was developed based on previous experience gained doing similar research. Patients with PCD can experience sudden drops in blood pressure if they are moved too quickly to an upright position (Fan, 2004). As a result of earlier studies, blood pressure monitoring during a participant's position change became a standard part of the transfer procedure (Thompson, Bowman, Kitson, de Bono, & Hopkins, 1996).

Initially, the researcher changed the participant's position from prone to sitting very slowly while monitoring blood pressure and pulse. If these vital signs did not change significantly, the researcher allowed the participant to remain in the chair initially with back support. Once the participant achieved cardiovascular stability while sitting on a back-supported chair, the SB intervention was started the following day.

The aim was to have the participants sit on the backless chair for approximately 30 minutes twice a day (Okubo et al., 2008.). If the participant appeared to be fatigued or displayed any discomfort, the SB intervention was terminated immediately. After the participant was moved to the backless chair, blood pressure and pulse were checked: after 5 minutes of sitting then 15 minutes later. If the blood pressure and pulse changed significantly, the participant was returned to a back-supported position. The researcher also attached the EEG leads during the first 5 minutes.

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Ethical Considerations

The St. Luke's College of Nursing Ethics Committee approved the study, and the hospital consented to the research. Given the inability of the patient to provide consent, the patient's family or physician provided proxy informed consent. The researcher explained the study protocol, human participant's protection, and risks to the nurse manager, the physician, and staff nurse in charge and the family of each participant. The family and physician understood that they could withdraw the patient from the study at any time without penalty. A contingency was created for continuance of this treatment if a patient's condition improved and/or if the patient was transferred or discharge. Confidentiality and anonymity were maintained.

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Data Analysis

Data analysis conformed to the assumptions of nonparametric statistical analysis. The length of time for SB was analyzed as means and ranges. The Wilcoxon's rank sum test was used to analyze the pairs of Kohnan PCD Scale and EEG scores gathered before and at the midway point of each SB intervention session. The Kohnan PCD Scale and EEG scores taken before (baseline period) and during the SB intervention phase were reanalyzed using repeated-measures analysis of variance because there were more than two variables being measured and the outcome variables (Kohnan PCD Scale and EEG) were measured more than once. The statistical analysis software used was SPSS Version 12.0, and the significant difference level was set at p < .05. It is instructive to examine the trajectory of the Kohnan PCD Scale and EEG scores over time for each case. Kazdin (1982) explained that in single-case research design studies, visual data inspection is often all that is needed to determine whether an intervention is altering a selected behavior.

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Results

Case 1

The mean ± SD sitting time of the patient's SB sessions was 29.7 ± 5.3 minutes, and the range was 14 to 41 minutes. The duration of her SB intervention was 65 days. She evidenced no alpha or beta wave EEG activity during the baseline period (Table 1). Her level of consciousness before and midway through each SB session did not change (Table 2). The Wilcoxon's rank sum test indicated that there were no significant differences in her Kohnan PCD Scale scores.

Table 2
Table 2
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The Kohnan PCD Scale scores showed little variability, never dropping below the very severe range throughout the entire intervention period. At the end of the first 6 weeks of the SB intervention, the participant's total Kohnan PCD Scale score had decreased from 68 to 65 points (Mdn = 66.5) and then stabilized at 66 points until the eighth week of the study, when more variations were noted, although those variations were not clinically significant (Table 2). Two of the seven Kohnan PCD Scale items, however, did indicate some positive change: voluntary movement and response and comprehension. Subtle behaviors that appeared during the fifth week were movement of the left thumb and eyes opening for a longer period. The EEG reading 2 weeks after the beginning of the study indicated an increase in theta, alpha, and beta waves. After the 2-week point, the participant's theta waves did not increase further, but her alpha waves continued to increase from 0 at baseline to 64 at week 8 (Table 2).

The Wilcoxon's rank sum test indicated that there were no significant differences in any of the participant's EEG data. The alpha wave pattern began showing more activity during the second week of the intervention period, and alpha wave activity showed significant increases and considerable variability until the middle of the seventh week. The beta waves remained flat during the baseline phase and the first 8 days of the intervention period. Small shifts were seen during the second week, and then the beta waves remained flat until the end of the fourth week. The beta waves increased during the fifth week and into the sixth week, during which time the alpha waves showed wide variation. The beta waves returned to 0 and remained there until the 59th day of intervention, when there was a pronounced peak, which occurred at the time the other brain waves appeared to have synchronized during the final 10 days of the 65-day study. It is worth noting that 2 weeks after the alpha waves began to increase and slight increases in beta waves became apparent, the participant's Kohnan PCD Scale score became fairly stable (Table 2). Given her severe PCD condition, it is unknown if extended intervention would have further lowered the Kohnan PCD Scale score or increased her beta waves.

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Case 2

The patient's mean ± SD sitting time during the SB intervention sessions was 10.7 ± 4.8 minutes, and the range was from 6 to 25 minutes. The participant's tendency to vomit while in the seated position limited the length of sitting time, and her brain waves could not be measured at the midway point of the intervention due to the vomiting. The intervention period in this case lasted 36 days (Table 1). Although she was the oldest of the three patients, this woman's Kohnan PCD Scale score was the lowest during the baseline period. Her Kohnan PCD Scale score began a slight downward trend early in the intervention period (Table 3 and Figure 3). By the end of the first week, her highest Kohnan PCD Scale score was almost the same as the low points reached during the baseline period. The final Kohnan PCD Scale score of 52 placed her in the moderate category.

Table 3
Table 3
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Figure 3
Figure 3
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Changes in the participant's level of consciousness before and during the SB intervention period are displayed in Table 3 and Figure 3. Her total Kohnan PCD Scale score decreased from a high of 65 to a low of 48 points, with a median score of 55. The median score decreased to 58 points at 3 weeks and to 52 points at 5 weeks.

Four of the seven Kohnan PCD Scale criteria evidenced some positive change: voluntary movement, ophthalmography and visual recognition, vocalizing and utterances, and response and comprehension. Subtle changes noted were stronger voice volume and rapid movement of her left thumb at 5 weeks. The participant's level of consciousness also showed changes before compared with the midway point of each SB intervention session. The total Kohnan PCD Scale score just before the SB intervention sessions ranged from 65 to 58 points, with a median of 63. According to Wilcoxon's rank sum test, the midway score was significantly different from that before the intervention session (p = 0.002) began.

The alpha and beta brain wave scores showed increased activity beginning at the end of the second week of intervention. For the next 3 weeks until the end of the study, the participant's alpha and beta waves were active, producing an irregular pattern. It took several days for her Kohnan PCD Scale score to reflect the brain wave changes, all of which occurred between days 13 and 18 (Figure 4). The Wilcoxon's rank sum test indicated that there were significant differences in all the brain waves based on the EEG data (p = 0.039).

Figure 4
Figure 4
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Case 3

The patient's mean ± SD sitting time of the SB sessions was 36.4 ± 6.2 minutes. The shortest time was 24 minutes, and the longest time was 56 minutes. The duration of the intervention was 43 days (Table 4). The participant's Kohnan PCD Scale score was relatively stable until the fourth week of intervention, at which point it began to drop, creating a downward trend (Table 4 and Figure 5). Changes in the level of consciousness of this participant before and during the SB are shown in Table 4 and Figure 5. The total Kohnan PCD Scale score decreased from 68 to 57 points, with a median of 63. The total score decreased to its lowest figure of 57 points at 6 weeks.

Table 4
Table 4
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Figure 5
Figure 5
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Three of the seven Kohnan PCD Scale criteria indicated some positive change: ophthalmography and visual recognition, response and comprehension, and change of expression. A subtle change noted at 4 weeks was closing of the participant's mouth. At 5 weeks, he was opening his eyes, which subsequently stayed open longer, and moving his left arm slightly. Using the Wilcoxon's rank sum test, the SB midway score was significantly different from the baseline score (p = 0.007).

The alpha and beta waves were almost zero from the baseline period until the 19th day of the intervention, when those scores began a dramatic increase (Figure 6). At that point, all of the brain wave scores appeared to have achieved some semblance of coherence. In comparing this timeframe with the participant's Kohnan PCD Scale scores, it took approximately 1 week for the Kohnan PDC Scale score to change after the appearance of the increased alpha and beta wave activity. The Wilcoxon's rank sum test indicated that the SB intervention midway EEG score was not significantly different from the before EEG score for all waves (p = 0.032).

Figure 6
Figure 6
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Discussion

All three participants in this study experienced changes in consciousness as measured by the Kohnan PCD Scale scores and EEG readings. In two of the three cases, improved consciousness levels were documented 6 weeks after the beginning of the intervention period. This is the first recorded evidence suggesting that SB can improve the consciousness level of some patients with PCD.

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Kohnan PCD Scale Scores and Changes in Subtle Responses

The three participants, victims of cerebrovascular insults, were in a PCD condition for more than 3 months after symptom stabilization. Physicians had completed all proactive medical treatment, and the patients were about to be transferred to home care or a nursing home facility. Generally, in cases of severe consciousness disturbance where the PCD continues for more than 3 months, the possibility of emerging from that state is extremely low (Higashi et al., 1981; Sato et al., 1979).

The Kohnan PCD Scale score totals for the three participants before introducing the SB intervention fell within either the very severe or the severe category ranges. Despite this fact, two of the participants showed improvement in their consciousness levels after approximately 1 month in response to the SB intervention. The improvement was particularly noteworthy for cases 2 and 3, in which subtle responses, such as small finger movements, longer intervals with eyes open, and changes in voice volume, were also confirmed by the researcher.

In previous studies examining improvements in consciousness level, the first indications noted to appear are changes in expression and eye movements such as following an object and gazing steadily (Furukawa & Hayashi, 1996; Hiramatsu, 1998; Tsuruhara, Murayama, Tomonari, Fukada, & Itoh, 1997). In published reports where SB was used, other changes such as being able to hold up the head and small movements of the limbs appeared most quickly in addition to the changes in expression and eye movement (Akizuki et al., 1996; Hiramatsu, 1998). Similar results were obtained in this study. Among the longer term changes after more than 1 month, clear improvement was seen in the Kohnan PCD Scale scores and subtle responses in all three cases, but significant positive changes just before and then midway during the intervention period using the daily SB sessions were seen only in cases 2 and 3. It is important, therefore, to examine changes over a longer period as opposed to preliminary observations made during a shorter period of intervention.

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Changes in Brain Waves

Brain waves express activity of the cerebral cortex (Nishimura et al., 1991), and a positive correlation has been reported with cerebral blood flow (Ohkuma, 1999). Alpha waves reflect activity of the reticular formation of the brain stem. The alpha rhythm is a regular wave and is the most noticeable component of the brain waves, recorded from the scalp while at rest with the eyes closed. Theta waves appear with a reduction in the consciousness level, whereas delta waves are recorded in a deep sleep state. The appearance of wide delta waves indicates an overall reduction in brain function (Hoshi et al., 1998).

In this study, all three participants exhibited increases in alpha and beta brain wave components in response to the introduction of the SB intervention. It is hypothesized that these phenomena were due to the activation of the cerebral cortex and brainstem reticular formation. It is not sufficiently clear, however, in what way changes in posture are related to consciousness levels or stimulation of the cerebral cortex and brainstem reticular formation. A wide variety of integrated inputs from the spinal cord, medulla oblongata, midbrain, cerebellum, and cortex levels regulate posture and make coordinated movement possible (Hoshi et al., 1998). Changes appear in the physiology of the human body in space, where there is no effect of gravity (Toyama, 1999). Among the changes that are thought to be more important are muscular inertness and atrophy and a decrease in skeletal volume.

Similar changes have been predicted to appear from long-term confinement to a bed (Gunji & Suzuki, 1998; Hiramatsu, 1998). It seems that sensory stimulation from different parts of the body decreases with bed rest when the bones and muscles are not used. Because stimulation from the various body parts reaches the cerebral cortex sensory area via the reticular formation of the brain stem and the thalamus (Suzuki, 1993; Toyama, 1999), a decrease in these stimuli reduces stimulation of the cerebral cortex and relates to the continuation of a reduced consciousness level.

It is thought that SB causes the cerebral blood flow to increase because intraventricular pressure drops when the head is raised. In fact, it is widely acknowledged in clinical practice that raising the head during the acute stage of severe brain injury reduces intracranial pressure and increases cerebral perfusion pressure (Fan, 2004). It is possible, therefore, that using the SB intervention could improve consciousness in PCD patients by increasing cerebral blood flow.

Furthermore, this study showed in all three cases that both alpha and beta waves appeared 1-2 weeks before physical reactions took place, as evidenced by a drop in the Kohnan PCD Scale score and various subtle reactions. The reason for the somewhat later appearance of lower Kohnan PCD Scale scores and the subtle reactions than the EEG changes is not clear; however, this is a very interesting finding. Honma et al. (1997) reported that the appearance of alpha and beta waves and patient reactions were simultaneous, whereas the research literature indicates that patient reactions occurred several days after the appearance of alpha and beta waves when spinal cord stimulation was attempted on patients with PCD (Funahashi et al., 1993). It seems that the difference in time between improvements in EEG results and the patient reactions could depend on the actual degree of consciousness disturbance.

When designing interventions for PCD patients, it is critical to understand the manner in which patients respond, including how long it takes before responses begin to appear. Unless nurses fully understand the subtle behavioral changes that may result from their interventions, they may give up prematurely or get discouraged because of an apparent lack of progress. With this study result, responses of functional level changes in participants were not significant, although some subtle changes in EEGs were noted on some participants. With the introduction of SB, the frequency of interactions between nurses and participants and between family members and participants are increased, and it appears that there are at least some positive results for participants, family members, and nurses. It is also possible that these subtle changes may be a byproduct of the increased and more frequent interactions with family members and nursing staff rather than the SB interventions themselves. It would require further studies to determine this. In addition, these same nurses recognized more satisfaction with the care that they provided as well as with the convenience of using SB.

The results of this study indicate that the apparent changes in consciousness seem to be clinically significant, which, in turn, raises a number of other issues. Is there an optimal time to begin the SB intervention? Is the cost of implementing it warranted given the outcome? Is there a population of patients that would benefit the most from this form of intervention? Consequently, continued research using this promising method of neurological stimulation needs to be conducted in the future.

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Limitations and Future Issues

There were several threats to internal validity in this study, including history, maturation, and instrumentation. In terms of history, with the introduction of SB, the frequency of interactions between nurses and participants and between family members and participants was increased, and it appeared that there were at least some positive results for participants, family members, and nurses. It is also possible that these subtle changes may be a byproduct of the increased and more frequent interactions with family members and nursing staff rather than the SB interventions themselves. It would require further studies to determine this. Interestingly enough, these same nurses recognized more satisfaction with the care that they provided as well as with the convenience of using SB.

Maturation suggests that, perhaps, these three patients would have made the reported improvements in consciousness even without the aid of the backless chair. The single-case design does not provide control for that possibility. Based on previous research about recovery from the persistent vegetative state, however, the likelihood that any improvement was a result of history is very small.

Instrumentation, on the other hand, may be a more realistic threat. The researcher was the only person responsible for the Konan PCD Scale scoring, and over time, the scoring became more susceptible to improvement. Although the researcher received extensive training in Konan PCD Scale scoring and had a high interrater validity rating, a second person responsible for Konan PCD scoring would minimize this limitation. In addition, the method of calculating the EEG transformed score should be subjected to psychometric testing. Although the SB intervention may appear costly in terms of nursing care time and effort, it may prove to be advantageous in the long run. Research regarding ancillary benefits such as improved skin condition and better lung functioning also should be explored in the future.

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Summary

This study was designed to determine what changes would occur in the consciousness of PCD patients when they were placed in a backless chair every day for at least 1 month. From the data, the researcher found that each patient had at least subtle changes and sometimes pronounced improvements in his or her Kohnan PCD Scale score and EEG wave activity. This relatively simple nursing intervention has promise and needs to be explored further in the future in a study involving a larger sample size with a greater variety of participants.

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Acknowledgments

The author extends her sincerest gratitude to the participants, their families, and the medical personnel who participated in this study, as well as the nurses, doctors, and other healthcare professionals at Neurological Hospital in Tokyo, Japan, for their assistance, with special appreciation extended to Professor Michiko Hishinuma of St. Luke's College of Nursing in Tokyo and Professor Sarah Porter of Emeritus, School of Nursing, Oregon Health and Science University, for supervising this research project for editing this manuscript.

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