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Anesth Analg 2003;97:839-842 © 2003 International Anesthesia Research Society
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Abstract |
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The first change of dressings after skin grafting in burn patients is a source of great anxiety because of pain anticipation and the immediate and first confrontation with the result of skin grafting. We designed this dose-finding study to determine the feasibility and safety of patient-controlled sedation (PCS) using propofol during these procedures. Twenty patients were familiarized with the PCS and asked to use PCS whenever they felt uncomfortable or anxious. Analgesia was provided by a single bolus of morphine IV 15 min before the procedure according to their daily intake. The first 10 patients used a fixed bolus of propofol 0.3 mg/kg and a lockout of 5 min. The degree of sedation was measured using bispectral index (BIS) monitoring. Demands versus delivery of propofol boluses were recorded. Within 1 h after the procedure, pain intensity was evaluated and satisfaction scores obtained from patients and nurses performing the dressing changes. In the first 10 patients, there were no respiratory rates <10 breaths/min, systolic and diastolic blood pressure were within 25% of baseline values, and peripheral saturation stayed more than 94% with additional small flow oxygen via nasal insufflation. There were double the demands than actual deliveries of propofol boluses. The BIS did not show significant decreases of <80 in any patient reflecting an insufficient state of sedation. Because the interim analysis of the efficacy of the PCS setup showed an insufficient state of sedation, a different PCS setup was evaluated in a second group of 10 patients (an individualized propofol bolus, titrated to achieve a significant decrease of BIS or a sleepy state, and no lockout period). The second group of patients showed a more effective sedation, with respiratory and hemodynamic variables being not significantly different from the first group of patients. PCS with propofol is feasible in burn patients and can be used safely. To provide an optimal sedation, we suggest to initially titrate the bolus to achieve a significant decrease of BIS or a clinically effective state of sedation and to abolish the lockout interval.
IMPLICATIONS: Patient-controlled sedation with propofol is safe and can be used in burn patients undergoing nonoperative procedures. To provide an effective sedation state, we suggest to initially titrate the bolus to achieve a significant decrease of bispectral index or a clinically effective state of sedation and to abolish the lockout interval.
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Introduction |
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Victims of burn injuries suffer severe forms of trauma affecting them both physically and psychologically. The pain experienced by these patients is not only because of the burn injuries themselves, but also is associated with the numerous therapeutic procedures performed on a daily basis during their hospital stay (1–3). In addition to pain, burn patients also face helplessness and dependency, and many of them experience various forms of psychological distress during their hospitalization. These reactions include anxiety, frustration, anger, and depression to varying degrees, which can degenerate into psychiatric disorders (e.g., posttraumatic stress disorder or major depression) (4,5). In a follow-up study of posttraumatic stress and psychological impairment after burn injury (6), up to 45% of burn patients suffered from psychological sequels, with 20%–25% developing posttraumatic stress syndrome. Among the therapeutic procedures they undergo, the most common nonoperative procedure involves the daily change of dressings. The first change of dressings after skin grafting is probably the most painful and a source of great anxiety because of the immediate and first confrontation with the result of skin grafting.
Several therapeutic approaches have been studied to provide analgesia, comfort, or sedation during these procedures such as conventional methods of analgesia using opioids, sedation using benzodiazepine or propofol, and alternative methods of pain treatment using acupuncture (7), and psychological methods of sedation such as hypnosis or stress-reducing therapy (8,9) have provided various degrees of success.
Propofol is extensively used for sedation during operative and nonoperative procedures. However, the individual demands are difficult to judge and meet effectively when propofol is administered by health care providers. Propofol patient-controlled sedation (PCS) seems an interesting alternative because it allows the patient to feel in control of the situation by self titrating the level of comfort desired. This study was designed as a dose-finding study to determine the feasibility and safety of PCS using propofol in burn patients undergoing the first dressing change after skin grafting surgery.
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Methods |
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This study was conducted at the Burn Centre of the Hôtel-Dieu hospital after approval of the local ethics committee. It was designed as a prospective study of 20 conscious burn patients undergoing first dressing changes 5 days after skin-grafting surgery. This procedure is performed with the patient soaking in a large bath to facilitate the removal of the dressings (Fig. 1). All patients were familiarized with the PCS setup, and written consent was obtained. We excluded patients in whom propofol was contraindicated and patients unable to understand the use of PCS.
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All patients were asked to press the button whenever they felt uncomfortable or anxious. IV morphine was used to control procedural pain before the procedure. All patients received either 0.1 mg/kg + 10% of the total oral morphine intake during the last 24 h or three times the hourly dose when morphine was given IV as a continuous infusion but at least 0.15 mg/kg 15 min before the beginning of dressing changes. Bispectral index (BIS) monitoring using the A-2000 BISTM monitoring system (Aspect Medical Systems, Newton, MA) with the standard BIS sensor was applied to all patients and the smallest BIS recorded every 2 min along with pulse oximetry, noninvasive blood pressure, and the respiratory rate. If saturation decreased to <94%, oxygen was insufflated nasally at 4 L/min.
Because no data were available in the literature on the use of propofol PCS in burn patients, this study was designed as a dose-finding study. It was separated into two parts, with the first 10 patients serving as the group to test the efficacy and safety of a PCS with a fixed bolus of propofol 0.3 mg/kg and a lockout period of 5 min. The results of this first part lead us to change the fixed bolus of 0.3 mg/kg and the 5-min lockout regimen. In the second group of 10 patients, the initial bolus was titrated to achieve a significant decrease of the BIS value (at least 15%) or a sleepy (spontaneous eye closure) patient. If insufficient effect was seen within 2 min with a starting dose of 0.3 mg/kg, an additional bolus of 0.1 mg/kg was given until the desired level of sedation was obtained. This dose then served as the bolus of subsequent doses self-administrated by the patient. No lockout period was used. Within 1 h after completion of the dressing change, each patient was asked to rate the intensity of the pain experienced during the procedure using a numeric scale from 0 to 10 (0 = no pain; 10 = unbearable pain). A satisfaction score was obtained from the patient and the nurse responsible for the procedure more than 1 h after the procedure using a Likert type scale (10) (1 = very dissatisfied; 6 = very satisfied). Nurses were asked to rate their satisfaction with the conditions during dressing changes by judging the efficacy of sedation and feasibility of dressing changes.
Data are presented as mean ± SD. Anthropometric data, hemodynamic variables, duration of dressing changes, morphine dosages, pain scores, and satisfaction ratings of the patients who participated in the first and second phase of the study were compared using the rank-sum test, and P < 0.05 showed a significant difference.
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Results |
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The mean age of the first 10 patients was 38 ± 16 yr, with a mean total body surface of 14% ± 3%. They underwent dressing changes of 25 ± 5 min. Only a modest decrease in saturation was noted in 5 of 10 patients (none <90%), which was corrected by the administration of oxygen nasally. Arterial blood pressure was within 25% of baseline values obtained at the beginning of the procedure throughout the procedure in all patients, and no respiratory rates <10 breaths/min were recorded. However, the number of demands was twice the actual doses received (six ± two demands versus three ± one deliveries). Furthermore, there was no substantial decrease of BIS nor a clinical sign for an effective sedation, which suggests that a fixed bolus of 0.3 mg/kg and a lockout period of 5 min are not effective to induce an adequate sedation in all patients. The pain score was 3.4 ± 2 during the procedure after an initial bolus of morphine of 15.2 ± 2.4 mg. Satisfaction scores were 5.4 ± 0.8 for the patients and 5.2 ± 0.5 for the nursing staff without being statistically different.
The second group of patients was not different from the first one in age (37 ± 13 yr) and burn total body area (20% ± 10%). The procedures lasted 22 ± 4 min. The titrated bolus was 0.47 ± 0.09 mg/kg to produce an objective state of sedation, a decrease of BIS of at least 15% from the initial value (n = 7), or a sleepy (spontaneous eye closure) patient (n = 3). Throughout the procedure, BIS varied from 59 to 98 with every bolus creating a change in the degree of either BIS or consciousness of the patient (Fig. 2). Saturation stayed more than 94% in all patients, 5 of 10 patients required supplemental oxygen, arterial blood pressure remained within 25% of baseline values, and no respiratory rates <10 breaths/min were recorded during the entire procedure. During the procedure, the number of demands was 5 ± 3. The pain score was 3 ± 1.8 during the procedure after an initial bolus of morphine 13.4 ± 3 mg. Satisfaction scores for patients and nurses were 5.8 ± 0.2 and 5.9 ± 0.3, respectively, without being different. The duration of the procedure, the doses of morphine applied, pain and satisfaction scores, and peripheral saturation were not statistically different between the two groups.
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Discussion |
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TopAbstractIntroductionMethodsResultsDiscussionReferences |
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The results of this study show that PCS with propofol is feasible and can be used safely for providing sedation during dressing changes in burn victims. A fixed bolus of 0.3 mg/kg with a refractory period of 5 min was safe but did not provide adequate sedation, as observed by an absence of change in the BIS. When a bolus is initially titrated using either a predefined decrease of BIS by 15% or a sleepy state and no lockout period is used, not only is a more effective state of sedation achieved, but this form of sedation is as safe as the more conservative setup in the first group.
The control of sedation by observation or communication is sometimes difficult and genuinely subjective. Most studies rely on judging or defining the level of consciousness by actively interacting with the patient (e.g., reaction to verbal response). However, active interaction may change the level of consciousness. Nurses were asked not to interact with the patient unless the patient himself initiated a conversation to avoid a change in the sedation level and provide an adequate evaluation of the effect of the propofol bolus. We used the BIS to objectively monitor the degree of sedation during PCS without active interaction. The BIS monitor is a good predictor of the level of sedation and unconsciousness during propofol infusion (11). Part of the new A-2000 monitoring device is a control of facial electromyographic activity to assess the signal quality. It was very important to ensure minimal head movement during the study period to obtain correct BIS values or any BIS values at all. The signal quality improves with increasing depth of sedation.
However, clinical experience before the study indicated that in some patients, BIS monitoring did not adequately reflect subtle changes in consciousness; patients fell asleep (spontaneous eye closure) without a substantial change in BIS (more than 10%). We therefore deliberately designed our study to define a sufficient effect of sedation not only by a significant decrease in BIS (more than 15% change), but also by achieving a sleepy state as indicated by spontaneous eye closure.
Sedation during dressing changes has traditionally been provided using midazolam or lorazepam administrated by nurses. Propofol offers several potential advantages for these relatively short procedures, including its short duration of action, facilitating titration of sedation, and its antiemetic properties. One study showed that propofol is a more suitable drug for PCS compared with midazolam because of its more rapid response to fluctuating patient requirements and lesser effect on memory and mental performance (12).
The patient-controlled modality for sedation with propofol has provided safe and effective sedation in dental and day-case surgeries under local or regional anesthesia (13,14). Two studies compared PCS using propofol to anesthesiologist-controlled continuous perfusion of propofol (15,16). These studies showed similar effectiveness of the PCS method when compared with anesthesiologist-controlled propofol and a similar or greater satisfaction rate among patients. However, finding the right dose and lockout period for each individual can be difficult and may lead to under or oversedation (17,18). We therefore chose a more conservative approach in our initial setup of PCS with a small dose of propofol of 0.3 mg/kg and a fixed interval of five minutes. The titration of an individual bolus for each patient as chosen in the second group of patients seems to guarantee the best success in providing a sufficient state of sedation and eliminates the necessity of a refractory interval. Although BIS monitoring offers the advantage of objective determination of different degrees of consciousness without disturbing the patient, a conventional estimation of the level of sedation by observational methods (e.g., spontaneous eye closure) might be an alternative when BIS monitoring is not available or impossible.
Whether the control aspect of this form of sedation may contribute to ease the psychological disturbance created by serious burns is beyond the scope of this study. Individual response to control may depend on personality, but in general, personal control over an unpleasant event may reduce the stress associated with the event. However, the patient-controlled modality could be of significant benefit to severe burn victims who undergo tremendous psychological disturbances and a great level of anxiety because PCS gives them a sense of control over a situation where they feel helpless. This should be the focus of future studies.
In conclusion, PCS with propofol can be used in burn patients undergoing nonoperative procedures. To provide an effective sedation state, we suggest to initially titrate the bolus to achieve a significant decrease of BIS or a clinically effective state of sedation and to abolish the lockout interval.
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Acknowledgments |
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Supported, in part, by funds from the Department of Anesthesiology of the CHUM and the Quebec Foundation of Firefighters.
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References |
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- Latarjet J, Choinière M. Pain in burn patients. Burns 1995; 21: 344–8.[Medline]
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- Baur KM, Hardy PE, Van Dorsten B. Posttraumatic stress disorder in burn populations: a critical review of the literature. J Burn Care Rehabil 1998; 19: 230–40.[Medline]
- Thomas CR, Meyer WJ, Blakeney PE. Psychiatric disorders associated with burn injury. In: Herdon DN, ed. Total burn care. 2nd ed. WB Saunders, 2002: 766–73.
- Madianos MG, Papaghelis M, Ioannovich J, et al. Psychiatric disorders in burn patients: a follow-up study. Psychother Psychosom 2001; 70: 30–7.[Medline]
- Lewis SM, Clelland JA, Knowles CJ, et al. Effects of auricular acupuncture-like transcutaneous electric nerve stimulation on pain levels following wound care in patients with burns: a pilot study. J Burn Care Rehabil 1990; 11: 322–9.[Medline]
- Frenay MC, Faymonville ME, Devlieger S, et al. Psychological approaches during dressing changes of burned patients: a prospective randomised study comparing hypnosis against stress reducing strategy. Burns 2001; 27: 793–9.[Medline]
- Meyer WJ, Marvin JA, Patterson DR, et al. Management of pain and other discomforts in burned patients. In: Herdon DN, ed. Total burn care. 2nd ed. WB Saunders, 2002; 747–65.
- American Pain Society. Quality improvement guidelines for the treatment of acute pain and cancer pain. JAMA 1995; 274: 1874–80.
[Abstract/Free Full Text] - Schraag S, Bothner U, Gajraj R, et al. The performance of electroencephalogram bispectral index and auditory evoked potential index to predict loss of consciousness during propofol infusion. Anesth Analg 1999; 89: 1311–5.
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- Girdler NM, Rynn D, Lyne JP, Wilson KE. A prospective randomised controlled study of patient-controlled propofol sedation in phobic dental patients. Anaesthesia 2000; 55: 327–33.[Web of Science][Medline]
- Osborne GA, Rudkin GE, Jarvis DA, et al. Intra-operative patient-controlled sedation and patient attitude to control: a crossover comparison of patient preference for patient-controlled propofol and propofol by continuous infusion. Anaesthesia 1994; 49: 287–92.[Web of Science][Medline]
- Henderson F, Absalom AR, Kenny GN. Patient-maintained propofol sedation: a follow up safety study using a modified system in volunteers. Anaesthesia 2002; 57: 387–90.[Web of Science][Medline]
- Smith AF, Thorpe SJ, Cook LB. Patient-controlled sedation using propofol: randomized, double-blind dose refinement. Eur J Anaesthesiol 1999; 16: 18–22.[Medline]
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