| ||||||||||||||
|
|
|||||||||||||

Departments of Anesthesia,
*University of Iowa College of Medicine, Iowa City, Iowa, and
King Saud University, Riyadh, Saudi Arabia
Address correspondence and reprint requests to Mohamed Naguib, MD, University of Iowa College of Medicine, Department of Anesthesia, 200 Hawkins Dr., 6JCP, Iowa City, Iowa 52242-1009. Address e-mail to mohamed-naguib{at}uiowa.edu
| Abstract |
|---|
|
|
|---|
Implications: Premedication with 0.05 mg/kg melatonin was associated with preoperative anxiolysis and sedation without impairment of cognitive and psychomotor skills or affecting the quality of recovery.
| Introduction |
|---|
|
|
|---|
| Methods |
|---|
|
|
|---|
Approximately 2 h before surgery, patients were transported to an isolated quiet room in the operating suite. A pulse oximeter probe was placed on all patients, and SpO2, arterial blood pressure, and heart rate were recorded continuously. Resuscitative equipment was available at the bedside. Patients were randomly allocated to one of seven groups (n = 12 in each) to receive either 0.05, 0.1, 0.2 mg/kg sublingual midazolam, 0.05, 0.1, 0.2 mg/kg sublingual melatonin, or sublingual saline (placebo). We used midazolam ampule solution (0.5%) originally intended for IV use (Dormicum®) and colloidal melatonin (Innovative Natural Products, Escondido, CA). Study drugs and placebo were prepared to a fixed volume of 3 mL (in a syringe from which the needle had been removed) and marked only with a coded label to maintain the double-blinded nature of the study. The contents of the syringe was given sublingually approximately 100 min before the induction of general anesthesia by a resident not involved in the management of the patient or in data collection. The patient was first asked to place the tip of the tongue to the back of the upper teeth. The drug was then, placed under the tongue, the patient was asked to close her mouth, and was instructed, "Dont swallow!"; at 180 s, the patient was permitted to swallow the medication. We did not add any flavor to midazolam, because it has been reported that the addition of candy flavor did not improve acceptance of or compliance with sublingual midazolam administration (4).
A visual analog scale (VAS) was used for the patients to evaluate their anxiety. The scale is a 50-cm long and 10-cm high card, diagonally divided to a white and a bright red triangle. The centimeter scale was on the rear side of the card (5,6). The extremes were marked "no anxiety" at the white end; and "anxiety as bad as ever can be" at the red end. The same psychologist blinded to group assignment performed all test scoring and calculations in the perioperative period. The psychologist evaluated anxiety VAS, orientation score (0 = none; 1 = orientation in either time or place; 2 = orientation in both), and sedation score (1 = awake; 2 = drowsy; 3 = asleep, but arousable; 4 = asleep, but not arousable) before, and 10, 30, 60, and 90 min after the administration of premedication and after operation at 15, 30, 60, and 90 min after admission to the recovery room. In addition, patients were asked to perform the digit-symbol substitution test (DSST) (7,8) and Trieger dot test (TDT) (9) at these times. The DSST forms part of the performance scale of the Wechsler adult intelligence test. These tests were used to quantitatively assess the cognitive and psychomotor activity.
All patients were positioned with 30° head elevation and used the same writing implement (ballpoint pen, medium point, black) for all tests. The DSST score represented the number of correct symbol substitutions made in 60 s and the score was normalized according to a table (the normalized DSST or NDSST score). The TDT score represented the total number of missed dots (of 42) that were connected. TDT deviation represented the cumulative shortest distance (in millimeters) between the drawn line and missed dots. The time to perform the TDT was measured in seconds by using a stopwatch. To account for interpatient differences in test-taking ability, the anxiety VAS, NDSST, and TDT scores; TDT deviations; and time-to-perform TDT test were normalized to baseline scores, deviation, and time for each patient. Changes in scores of different tests and TDT deviation and TDT time relative to baseline values were compared.
Amnesia was assessed by showing patients two simple line diagrams before premedication. Patients were queried 24 h later as to recall of the diagrams, the entry into the operating room, and IV catheter insertion in the operating room.
In the operating room, an IV infusion of lacta-ted Ringers solution was started. Anesthesia was induced with 1 µg/kg fentanyl, 2 mg/kg propofol, and 0.2 mg/kg mivacurium. After tracheal intubation, anesthesia was maintained with isoflurane and 70% nitrous oxide in oxygen, supplemented with fentanyl. End-tidal concentrations of oxygen, nitrous oxide, isoflurane, and carbon dioxide were determined continuously by a multiple-gas analyzer (Capnomac; Datex Instrumentarium, Helsinki, Finland). Ventilation was adjusted to maintain normocapnia (end-tidal CO2 partial pressure 3540 mm Hg). Hemoglobin oxygen saturation was monitored by pulse oximetry. Temperature was monitored by a nasopharyngeal thermistor and was maintained at 36.5 ± 0.5°C. Neuromuscular function was monitored by a peripheral nerve stimulator. Surgery time (incision to surgery end), and anesthesia time (the induction to emergence) were recorded. In the recovery room, postoperative pain was quantitated by using a 100-mm VAS, and was assessed at 15, 30, 60, and 90 min after arrival to the recovery room. Postoperative pain was treated with incremental doses of IV morphine sulfate and the total dose administered was noted. Postoperative nausea and vomiting were treated with 4 mg IV ondansetron. On the second day, the patients were questioned by the same psychologist about their premedication: "Was the premedication satisfactory or not" and "If needed, would they prefer the same or another premedication in the future".
With a sample size in each of the seven groups of 12, a 0.05 level
2 test has 86% power to detect a difference in proportions characterized by a variance of proportions (V = S(pi - p0)2/G) of 0.045 and an average proportion of 0.607. Based on the findings of our previous study (3), we assumed that placebo would have an effect in 20% of patients, whereas different doses of midazolam and melatonin would have an effect in at least 50% of patients.
We used Dunnetts test to compare the control group to each of the other groups. Comparisons among the groups who received midazolam or melatonin were performed by using the Duncan multiple range test,
2 test, Fishers exact test, and the Kruskal-Wallis test for multiple comparisons. For multiple comparisons in the later test, the null hypothesis was rejected if ZSTAT was larger than the critical value ZC, where
|
|
Number needed to treat (NNT) was calculated for effect data (1012). The NNT is the number of patients who needed to be treated with melatonin (or midazolam) rather than the placebo for one additional patient benefit. Statistical analyses were performed by using the BMDP statistical package (7.01; University of California Press, Berkeley, CA, 1994) and StatXaxt for Windows (4.0.1; CYTEL Software, Cambridge, MA, 1999) on a Dell computer (Pentium III processor) operated by Microsoft Windows 98 (Roselle, IL). Unless otherwise specified, results were expressed as means ± SD, and were considered significant when P < 0.05.
| Results |
|---|
|
|
|---|
|
|
|
Orientation scores were similar, except at 15 min after operation. At that time, the number of patients that were not orientated in both time and place in 0.05, 0.1, and 0.2 mg/kg midazolam and melatonin groups were 5 (41.7%), 4 (33.3%), 5 (41.7%), 2 (16.7%), 2 (16.7%), and 6 (50%), respectively, compared with 1 (8.3%) patient in the placebo group (P < 0.05).
In the control and 0.05, 0.1, and 0.2 mg/kg midazolam and melatonin groups, the baseline NDSST scores were 9.2 ± 2, 12.3 ± 7, 10.2 ± 3, 9 ± 2, 9.7 ± 2, 8.7 ± 3, and 9.1 ± 3, respectively (P = NS); the TDT score for missed dots were 8.2 ± 6, 6.1 ± 4, 8.6 ± 5, 12 ± 8, 13.8 ± 7, 9.2 ± 7, and 5.4 ± 4, respectively (P = 0.01); the TDT deviation were 2.5 ± 3, 3.5 ± 2.6, 5.3 ± 5, 4 ± 4, 3.5 ± 2.7, 5.5 ± 4.7, and 3.4 ± 2.9 mm, respectively (P = NS); and the TDT time was 13 ± 3, 12 ± 5.6, 15 ± 4, 14 ± 4, 13 ± 6, 18 ± 6, and 13 ± 5 s, respectively (P = 0.03). Thirty minutes after the administration of premedication, patients in the three midazolam groups had significantly poorer performance on the NDSST test compared with melatonin and placebo groups (Figure 2). However, there was no difference in the TDT score, deviation, or time needed to perform the TDT test among all of the groups either before operation or in the recovery room (Figure 3). After operation, the placebo and 0.05 mg/kg melatonin groups performed the DSST significantly better at 15, 30, and 90 min than the midazolam groups (Figure 2). Patients who were deeply sedated (asleep, but not arousable; Table 2) were unable to perform the DSST and TDT and were not included in the statistical analysis.
|
|
|
| Discussion |
|---|
|
|
|---|
In our previously published study (3), we also noted that premedication with either 15 mg of midazolam or 5 mg of melatonin had significant decreases in anxiety levels and increases in levels of sedation preoperatively compared with the control subjects. We also noted that midazolam produced the highest scores of sedation at 30 and 60 minutes after the administration and significant psychomotor impairment in the preoperative period compared with melatonin or placebo (3).
The onset and the peak effect of midazolam-induced sedation were at 30 and 60 minutes, respectively, after sublingual administration. Other investigators have reported similar observations (13). Although the onset of melatonin-induced sedation was at 30 minutes after sublingual administration, the peak effect was at 90 minutes. We noted a similar pattern in our previously reported study (3). In fact, it has been shown, in a sleep-disturbed blind man and in patients with delayed sleep-phase syndrome, that successful amelioration of sleep disturbances was achieved when melatonin was administered two hours before bedtime (14,15). Melatonin was ineffective when administered at bedtime to the blind person, even when larger doses were used.
This study also demonstrated that both midazolam and melatonin were equally effective as premedicants for preoperative sedation. At 90 minutes, the NNT scores were similar between patients who received similar doses of midazolam or melatonin. The NNT defines the treatment-specific effect of an intervention (12). The clinical implication of this NNT is that, for example, one would treat three patients with 0.05 mg/kg midazolam or 2.4 patients with 0.05 mg/kg melatonin to produce preoperative sedation in one patient. A NNT score of 2 or 3 indicates that a treatment is effective (12).
Before operation, the DSST scores improved in the melatonin and control groups 10 minutes after the administration of melatonin and saline, respectively (Figure 2). This reflects learning behavior in these groups. In contrast, significant impairment in performance on the DSST relative to baseline was only in the midazolam group. This observation is consistent with our previously published data (3). These findings are also consistent with other studies that have shown psychomotor decrements after premedication midazolam (16,17). In contrast, several studies have demonstrated that melatonin (even in doses up 240 mg divided into three doses) did not impair either psychomotor performance or tests of memory and visual sensitivity (3,18). After operation, the placebo and 0.05 mg/kg melatonin groups performed the DSST significantly better at 15, 30, and 90 minutes than the midazolam groups (Figure 2).
It has been shown that the DSST is a more sensitive test than TDT for detection of the cognitive and psychomotor impairments (3,19). In this study, there was no difference in the TDT score, deviation, or time needed to perform the TDT test among all groups, either before operation or in the recovery room (Figure 3).
Benzodiazepines impair acquisition of new information with no effect on retention or retrieval of previously stored information (20). Midazolam, in particular, is reported to provide significant amnesia (21). In this study, midazolam diminished anterograde recall for the two preoperative events (entry into the operating room and IV catheter insertion) compared with melatonin and placebo groups. In accordance with our previously reported study (3), the results of this study indicated that melatonin had no amnestic effects (Figure 4). Although it is desirable in some situations to render patients amnesic to perioperative experiences, amnesia is considered undesirable in patients who wish to or need to have recall in the immediate postoperative period. For example, prolonged amnesia of the patient is not desired in the outpatient setting, as discharge may be delayed and instructions forgotten.
In conclusion, the administration of either 0.05, 0.01, and 0.2 mg/kg melatonin or midazolam was associated with adequate preoperative sedation, anxiolysis, and patient satisfaction. Doses of 0.2 mg/kg midazolam produced the highest scores of sedation at 30, 60, and 90 minutes after the administration. After operation, the psychomotor test results indicated that the course of recovery was faster in the 0.05 mg/kg melatonin group. The dose of 0.2 mg/kg midazolam decreased recall for two preoperative events compared with other groups. We conclude that premedication with 0.05 mg/kg melatonin was associated with preoperative anxiolysis and sedation without impairment of cognitive and psychomotor skills and without prolonging recovery. Therefore, 0.05 mg/kg melatonin appears to be an adequate dose for premedication. Melatonin appears to be a good choice for ambulatory surgery patients and in situations in which impairments of cognitive and psychomotor functions would be detrimental to the patients well-being.
| Acknowledgments |
|---|
The authors thank Fatma Khalid Al-Rifai, BSc, MCP, Department of Psychiatry, King Khalid University Hospital for her invaluable contribution to this study.
| References |
|---|
|
|
|---|
This article has been cited by other articles:
![]() |
W. Caumo, F. Torres, N. L. Moreira Jr, J. A. S. Auzani, C. A. Monteiro, G. Londero, D. F. M. Ribeiro, and M. P. L. Hidalgo The Clinical Impact of Preoperative Melatonin on Postoperative Outcomes in Patients Undergoing Abdominal Hysterectomy Anesth. Analg., November 1, 2007; 105(5): 1263 - 1271. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Naguib, A. H. Samarkandi, M. A. Moniem, E. E.-D. Mansour, A. A. Alshaer, H. A. Al-Ayyaf, A. Fadin, and S. W. Alharby The Effects of Melatonin Premedication on Propofol and Thiopental Induction Dose-Response Curves: A Prospective, Randomized, Double-Blind Study Anesth. Analg., December 1, 2006; 103(6): 1448 - 1452. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. R. J. Sury and K. Fairweather The effect of melatonin on sedation of children undergoing magnetic resonance imaging Br. J. Anaesth., August 1, 2006; 97(2): 220 - 225. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Capuzzo, B. Zanardi, E. Schiffino, C. Buccoliero, D. Gragnaniello, S. Bianchi, and R. Alvisi Melatonin does not reduce anxiety more than placebo in the elderly undergoing surgery. Anesth. Analg., July 1, 2006; 103(1): 121 - 123. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Eikermann, M. Blobner, H. Groeben, C. Rex, T. Grote, M. Neuhauser, M. Beiderlinden, and J. Peters Postoperative upper airway obstruction after recovery of the train of four ratio of the adductor pollicis muscle from neuromuscular blockade. Anesth. Analg., March 1, 2006; 102(3): 937 - 942. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Naguib, M. T. Baker, G. Spadoni, and M. Gregerson The Hypnotic and Analgesic Effects of 2-Bromomelatonin Anesth. Analg., September 1, 2003; 97(3): 763 - 768. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Naguib, P. G. Schmid III, and M. T. Baker The Electroencephalographic Effects of IV Anesthetic Doses of Melatonin: Comparative Studies with Thiopental and Propofol Anesth. Analg., July 1, 2003; 97(1): 238 - 243. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Naguib, D. L. Hammond, P. G. Schmid III, M. T. Baker, J. Cutkomp, L. Queral, and T. Smith Pharmacological effects of intravenous melatonin: comparative studies with thiopental and propofol Br. J. Anaesth., April 1, 2003; 90(4): 504 - 507. [Abstract] [Full Text] [PDF] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|