Patient-maintained propofol sedation: a follow ... - Wiley Online Library

Anaesthesia, 2002, 57, pages 387±403 .....................................................................................................................................................................................................................

FORUM

Patient-maintained propofol sedation: a follow-up safety study using a modi®ed system in volunteers F. Henderson,1 A. R. Absalom2 and G. N. C. Kenny2 1 Department of Anaesthesia, Western In®rmary, Dumbarton Road, Glasgow G11 6NT, UK 2 University Department of Anaesthesia, Glasgow Royal In®rmary, Glasgow, UK Summary

Patient-maintained sedation is a mode of patient-controlled sedation during which propofol is administered using a target-controlled infusion, with patient demand increasing the target concentration. A system tested previously for safety in our institution resulted in oversedation. Aiming to improve safety, we modi®ed the system by increasing the lockout period to 4 min, reducing the starting concentration to 0.5 lg.ml)1 and the increments on demand to 0.1 lg.ml)1. As in the previous study, healthy volunteers attempted to render themselves unconscious by frequently pressing the demand button. To assess effects on memory, volunteers were given keywords to remember every 15 min. The maximum target concentration reached varied between 1.0 and 2.5 lg.ml)1. No volunteers lost consciousness, however, one volunteer had a brief period of apnoea and oxygen desaturation. The Cp50 for loss of memory for words was 1.26 lg.ml)1. Although this version represents an improvement, we conclude that the system is not yet completely suitable for use without anaesthetic supervision. Keywords

Anaesthetics, intravenous; propofol. Sedation; patient-controlled.

. ......................................................................................................

Correspondence to: Dr F. Henderson This study was conducted in the Department of Anaesthesia, HCI (Scotland), Clydebank, UK. Accepted: 1 October 2001

Large numbers of surgical, medical, dental and radiological procedures are performed under sedation, but often in sites remote from the operating theatre, and without anaesthetic supervision. Moreover, in these circumstances the physician performing the procedure is usually the person responsible for administering the sedation and ensuring the safety of the patient, a situation which we believe is not appropriate. Traditionally, bolus dose techniques have been used, using drugs such as midazolam and pethidine. The use of these drugs in these circumstances may result in potentially fatal complications. It is dif®cult to judge the degree of anxiety suffered by patients [1], in addition, the surgical stimulus may change with time, whereas the onset of action of these drugs is slow and the duration of action relatively long. Our goal was to produce a system that produces optimal sedation with maximal safety. Patient control may enhance safety, and so a patient-maintained sedation (PMS) system has Ó 2002 Blackwell Science Ltd

been developed. PMS is a mode of patient-controlled sedation in which the sedative agent is administered by target-controlled infusion (TCI), and a patient demand causes the target to be increased. Absence of demands for more than a speci®ed period results in an automatic reduction in target level. The system has been used to provide sedation for patients undergoing orthopaedic surgery [2] and for premedication in day surgery [3]. The report of the Joint Working Party of the Royal College of Radiologists and Royal College of Anaesthetists, published in 1992, endorsed the view that sedation should be de®ned as a state of depression of the central nervous system Ôduring which verbal contact with the patient is maintainedÕ [4]. During a previous safety test, two volunteers were able to use our PMS system to induce loss of verbal contact [5]. The short lockout period used in that study (2 min) resulted in a signi®cant time-lag between the estimated blood and effect-site propofol 387

Forum Anaesthesia, 2002, 57, pages 387±403 . ....................................................................................................................................................................................................................

concentrations. Once the effect-site concentration was suf®cient to cause subjects to forget to press the button, the system, by de®nition, kept the blood concentration constant. However, the effect-site concentration would have continued to increase until it had equilibrated with the blood concentration. In two subjects, the effect-site concentration therefore increased above the threshold required for loss of consciousness. We have modi®ed the system by increasing the lockout time from 2 to 4 min, decreasing the initial target propofol concentration (CT) to 0.5 lg.ml)1, and reducing the increase in target on demand from 0.2 to 0.1 lg.ml)1. The effect of these changes is to reduce the time-lag between estimated target and effect-site concentrations. The aim of this study was to determine if these changes were suf®cient to ensure conscious sedation without causing oversedation. Methods

Following local ethics committee approval and informed consent, 20 healthy adult volunteers, aged 24±46 years, were enrolled into the study. Volunteers who had a history of use or abuse of sedative or psychoactive drugs were excluded. The PMS system has been described previously [5]. It consists of a Graseby 3400 pump connected via RS232 ports to a microprocessor programmed with the Marsh adult pharmacokinetic dataset [6]. The microprocessor calculates the infusion rates required momentby-moment and transmits these to the infusion pump. It also calculates and displays the estimated effect-site concentration [7]. The subjects fasted for 6 h before the study. They were shown how to use the control button and asked to attempt to deliberately induce loss of consciousness using the system. Venous access was secured and routine monitoring was commenced and continued throughout the study (non-invasive arterial pressure, ECG and pulse oximetry). The propofol infusion was started with the initial CT set to 0.5 lg.ml)1. After equilibration between estimated blood and effect-site concentrations occurred ( 5 min), the patient control handset was activated. Thereafter, the subject was able to increase the propofol CT in increments of 0.1 lg.ml)1 by clicking the control button twice within 1 s. The lockout period, before a further target increase could occur, was 4 min, and the maximum possible CT was 3 lg.ml)1. To assess the effects of propofol on memory subjects were given a keyword to remember every 15 min. Non-invasive arterial pressure (NIAP), heart rate (HR), respiratory rate, oxygen saturation and a modi®ed Steward sedation score [2] were recorded every 5 min. Subjects were observed continuously for signs of airway 388

obstruction. Supplementary oxygen by facemask was to be administered if the SpO2 was < 94% or the respiratory rate < 8. If subjects failed to press the activating device for 5 min but were still alert, they were given one further reminder. When the subject became too sedated to press the button or the maximum CT was reached, the infusion was discontinued, and he or she was observed until fully alert and able to walk unaided. Once able to walk, subjects were tested for spontaneous recall of keywords. Results

Data are presented as median [range]. Binary logistic regression was used to assess the Cp50 for loss of memory for words. Patient characteristics and main results are summarised in Table 1. All subjects reached a state in which they were too sedated to remember to press the button, but none failed to respond to verbal command. The median Steward score at this time was 7 and the minimum score of any subject at any time was 7. The median blood propofol concentration at maximal sedation was 1.7 lg.ml)1 and the median time taken for this to occur was 65 min. No volunteer had a decrease of > 10% from baseline of HR or mean NIAP. Airway control was maintained in all subjects, but one subject had a brief period of apnoea at an estimated blood propofol concentration of 1.0 lg.ml)1 associated with a decrease in SpO2 to 85%. On being told to take a breath he responded: ÔWhat, have I desaturated?Õ whereupon his SpO2 increased rapidly and remained > 94%. All other subjects had SpO2 ³ 93% throughout the study and did not require or receive supplementary oxygen. The Cp50 for loss of memory for words was 1.26 lg.ml)1 (odds ratio: 15.7, con®dence interval [3.3)73.8], p < 0.001). Median interval between stopping the infusion and mobilisation was 12 min. Discussion

Our goal was to develop a patient-controlled sedation system that provides optimal sedation without requiring anaesthetic supervision. Under these circumstances loss of consciousness, with the risk of loss of airway re¯exes, Table 1 Patient characteristics and main results. Age; years Gender, n; M:F Weight; kg Time to maximal sedation; min Maximum blood propofol concentration; lg.ml)1 Minimum Steward score Time between study end and mobilisation; min

32 [24±46] 14:6 69 [58±104] 65 [30±110] 1.7 [1±2.5] 7 [7±9] 12 [7±22]

Ó 2002 Blackwell Science Ltd

Anaesthesia, 2002, 57, pages 387±403 Forum . ....................................................................................................................................................................................................................

a

2

Propofol concentration (mcg.ml−1)

1.8 1.6 1.4 1.2 1 0.8 Blood concentration Effect-site concentration

0.6 0.4 0.2 0 0

300

600

900

1200 1500 1800 2100 2400 2700 Time (sec)

Propofol concentration (mcg.ml−1)

b

2 1.8 1.6 1.4 1.2 1 0.8 Blood concentration Effect-site concentration

0.6 0.4 0.2 0 0

300 600 900 1200 1500 1800 2100 2400 2700 Time (sec)

Figure 1 Computer simulation showing estimated blood and effect-site propofol concentrations for a volunteer who continually

presses the demand button of the PMS system. (a) The concentrations attained with the previous system, (b) the system reported in this study.


389


aspiration and airway obstruction, is not acceptable. When using a modi®ed PMS, 20 volunteers were able to sedate themselves, were unable to deliberately induce unconsciousness and quickly returned to a fully alert state. In the previous study, two subjects became oversedated at an estimated blood concentration of 1.4 lg.ml)1 [5]. Our suspicion that the starting target concentration of 1.0 lg.ml)1 used in that study was too high was con®rmed in this study when one subject reached maximal sedation at an estimated blood propofol concentration of 1.0 lg.ml)1. The increase in lockout period and reduction in the size of the increase in concentration on patient demand served to reduce the lag in equilibration between blood and effect-site concentrations (Fig. 1). If the threshold effect-site concentration for maximal sedation for a particular volunteer is assumed to be 1.0 lg.ml)1, then that individual will stop pressing the button once that effect-site concentration is reached. For this individual, Fig. 1a demonstrates that the effect-site concentration will end up being 0.4 lg.ml)1 above the threshold for maximal sedation, with the risks of loss of consciousness and airway re¯exes. For the same individual, Fig. 1b shows that with the settings used with our setting the overshoot is limited to 0.1 lg.ml)1. Although these changes were able to prevent loss of consciousness, they were not suf®cient to prevent a brief episode of apnoea in one volunteer. A possible improvement in safety was offset by an increase in the median time to maximal sedation to 65 min. In stressed patients, this delay may be even longer, and this is unlikely to be acceptable to patients and operators. The problems caused by the time-lag between blood and brain concentrations, and the delay before effective brain concentrations are reached may be overcome by using an effect-site targeted TCI algorithm, which manipulates the blood concentration to achieve almost step-wise increases in the effect-site concentration.

In conclusion, the modi®ed patient-maintained system showed better safety performance than the original prototype, but failed to prevent a brief period of apnoea in one subject, and cannot be recommended for use without anaesthetic supervision. Incorporation of effectsite targeting into the TCI system may enhance safety but may still allow for interindividual variation especially in the clinical setting. Acknowledgments

We would like to thank the Department of Anaesthesia, HCI (Scotland) who provided propofol, disposable materials and facilities to carry out the study. References 1 Dell R. A review of patient-controlled sedation. European Journal of Anaesthesiology 1996; 13: 547±52. 2 Irwin MG, Thompson N, Kenny GN. Patient-maintained propofol sedation. Assessment of a target-controlled infusion system. Anaesthesia 1997; 52: 525±30. 3 Murdoch JA, Kenny GN. Patient-maintained propofol sedation as premedication in day-case surgery: assessment of a target-controlled system. British Journal of Anaesthesia 1999; 82: 429±31. 4 Joint Working Party of the Royal College of Radiologists and the Royal College of Anaesthetists. Sedation and Anaesthesia in Radiology. Report of a Joint Working Party. London: Royal College of Anaesthetists, 1992. 5 Murdoch JA, Grant SA, Kenny GN. Safety of patientmaintained propofol sedation using a target-controlled system in healthy volunteers. British Journal of Anaesthesia 2000; 85: 299±301. 6 Marsh BJ, White M, Morton N, Kenny GN. Pharmacokinetic model driven infusion of propofol in children. British Journal of Anaesthesia 1991; 67: 41±8. 7 White M, Schenkels MJ, Engbers FH, et al. Effect-site modelling of propofol using auditory evoked potentials. British Journal of Anaesthesia 1999; 82: 333±9.

FORUM

A pilot study of patient-led identi®cation of the midline of the lumbar spine J. S. Wills,1 R. Bowie2 and D. G. Bogod3 1 University Department of Anaesthesia and Intensive Care, Queen's Medical Centre, Nottingham NG7 2RD, UK 2 Department of Anaesthesia, Royal Prince Alfred Hospital, Sydney, Australia 3 Nottingham City Hospital, Nottingham, UK 390



Summary

The midline of the lumbar spine is usually identi®ed by palpation of the spinous processes. Placement of an epidural or spinal needle is more dif®cult when these bony landmarks are impalpable. This pilot study investigated the ability of 50 healthy volunteers to identify the midline of their own backs, using light touch or proprioception. The midline as identi®ed in this manner was compared with the Ôgold standardÕ as de®ned by the interspinous line. Sensation to light touch was the most accurate, with 90% of the volunteers able to identify the midline to within 6.5 mm. Proprioception using a ®nger to touch the midline was less accurate. This study was carried out on volunteers with palpable spinous processes but suggests that, in certain circumstances, a patient-led identi®cation of the midline may be of value. Keywords

Anatomy; epidural space, lumbar vertebrae.

. ......................................................................................................

Correspondence to: Dr J. S. Wills This study was carried out at the Nottingham City Hospital. Accepted: 6 October 2001

Accurate identi®cation of the midline of the back facilitates the placement of an epidural catheter or spinal needle. The spinous processes are commonly used to identify the midline but may become impalpable with an increase in thickness of overlying tissue. Causes for this include obesity and oedema; when no clear bony landmarks of the midline are available, the contour of the soft tissues is often used as an indicator of the midline. In the obstetric population, the presence of oedema or obesity makes epidural or spinal placement more dif®cult. However, in conditions associated with oedema, such as pre-eclampsia, it can be even more important that epidural analgesia or regional anaesthesia is successful [1, 2]. It may be that the patient is able to identify his ¤ her midline with accuracy. This is because they are able to use at least three separate modalities of sensation to achieve this task. First, there is the proprioception involved in placement of the ®nger. Second, there is sensation of light touch on the skin and third, sensation to pressure on the spinous process and other deeper tissue. Each of these modalities could be used together to help the patient place his ¤ her ®nger over the midline. This is a preliminary study into the accuracy of two of these modalities, ®ne touch and proprioception, in volunteers. Methods

Fifty healthy volunteers were recruited to this study. During the study, two volunteers were not studied, one because of poorly palpable spinous processes and the other because of altered sensation as a result of a previous thoracotomy. The volunteers were informed of the


nature of the study and verbal consent was obtained. Following consultation, retrospective approval was sought and obtained from the local research ethics committee. In each case, the subject was asked to sit on a stool with a ¯exed lumbar spine, the position adopted by patients for epidural insertion. Two investigators carried out the assessments. Proprioception The subject was asked to use one ®nger to touch the skin overlying the midline of their back in the lumbar region. The subject was not allowed to practice this manoeuvre beforehand and once the ®nger had touched the skin it could not then be moved. By not allowing any correction of position once the skin was touched, any effect of sensation was eliminated. A ¯exible template was positioned around the ®ngertip so that the centre point of touch could be marked once the ®nger was removed. Sensation to light touch With the subject in the same position, the investigator tested the accuracy of sensation to light touch. This was carried out at a different lumbar level to that of the ®nger mark. Light vertical brushstrokes of 1 cm in length were made using the corner of a piece of light cardboard. The investigator started these strokes on the left side of the midline, moved towards it and eventually crossed over to the right side. This was then repeated in the opposite direction. The subject was asked to indicate when they thought that the brush strokes were over the midline. The whole process was continued until the subject was happy that the midline was identi®ed; there was no time 391


restriction on how long this took. The eventual chosen site was marked. Identi®cation of the midline Subjects who completed the study all had easily palpable spinous processes, and the interspinous line joining these was regarded as the Ôgold standardÕ for comparison. With the subject still in the same position, we identi®ed the midline by lining the edge of a ruler up along the spinous processes over at least ®ve vertebral levels. The distances of the marks on the skin from this ÔinterspinousÕ line were measured and the estimated vertebral level was documented. Also documented for the proprioception test were: the hand used, whether this hand was the dominant hand and, for each mark, whether it was on the near or the far side of the interspinous line to the hand used. Analysis Any points ipsilateral to the pointing hand were given a negative value for distance. The distribution for the results from each modality is shown in histogram form (SIGMAPLOT version 4.01) and the test for normality is the Kolmogorov-Smirnov goodness-of-®tness test (SPSS for Windows version 9.0.0 statistical package) [3]. The mean (SD) distances from the midline for each modality were calculated. Results

The results from 50 subjects are presented (34 male: 16 female). Nine of the subjects were left-handed. Five used their nondominant hand to identify the midline; of these, four were left-handed. The mean and range values for age, weight and body mass index (BMI) are shown in Table 1. In each case, the investigators identi®ed the interspinous line with ease. Test of normality Application of the one-sample Kolmogorov-Smirnov test failed to reject the null hypothesis that the data were normally distributed (p > 0.15 in each case). The distributions for each modality are shown in Fig. 1.

Table 1 Age, weight and body mass index (BMI) of the

volunteers.

Age; years Weight; kg BMI; kg.m)2

392

Mean (SD)

Range

36 (8.1) 76 (14.1) 24.5 (3.4)

23±60 49±115 17±34.8

Propioception The mean (SD) [95%CI] relative position of the point identi®ed by proprioception from the midline was 1.6 (7.5) [)16.3 to 13.5] mm ipsilateral to the identifying hand. The range was 27 to )29 mm. Sensation to light touch The mean (SD) [95%CI] position of the point relative to the midline, as identi®ed by sensation to light touch, was 0.0 (3.9) [)7.7 to 7.7] mm contralateral to the hand used in proprioception. The range was )10 to 11 mm. Discussion

This study was designed to investigate how accurately an individual can identify the midline of his ¤ her back using the sensory modalities of proprioception and light touch. It used as a comparison the interspinous line, routinely regarded by anaesthetists as the ÔmidlineÕ. For this to be possible, the spinous processes had to be palpable but the study could not allow the subjects to palpate these spinous processes when deciding on the midline. Both the Ôone-touchÕ technique of ®nger placement and sensation to light touch avoided stimulating the deep tissues. Sensation to light touch was the most accurate modality. The median and mean displacement from the midline were both 0.0 mm. This is not surprising as there is no reason to suspect that this type of sensation would be biased to one side rather than the other. Of more importance was the distribution. The full range for the 50 subjects was 21 mm, but 90% of the readings in this sample were within 6.5 mm of the midline. The variance for ®ne touch was smaller than for proprioception. The fact that the mean distance from the midline for proprioception using the Ôone-touchÕ technique was 1.6 mm ipsilateral to the hand suggests a tendency of the pointing hand to fall short of the midline. Of note with this technique were the two readings that deviated considerably from the midline (27 and 29 mm). The next furthest reading was 14 mm. There are several reasons why the patient in the clinical setting might be more accurate. We instructed the subjects to use a one-touch technique so that they did not palpate the spinous process ®rst before choosing the position on the skin. In the clinical situation, however, there is no reason why the patient should not use sensation from the spinous processes or other deeper layers to help them place their ®nger more accurately. The patient can take as long as necessary to palpate the area, assuming that there is no clinical urgency. The volunteers in this study had a good understanding of the instructions given to them and success with patients would require effective communication. Ó 2002 Blackwell Science Ltd


10 9

a

8 7 6 5 4 3 2 1

30 kg.m)2, and those with a history of convulsions or multiple allergies were not included. None were taking vasoactive drugs or antidepressants. Procedure All patients were premedicated with diazepam 5±10 mg given orally 1 h before surgery. Patients received midazolam 0.015±0.02 mg.kg)1 and fentanyl 1.0±1.5 lg.kg-1 or sufentanil 0.1±0.15 lg.kg-1 intravenously 2 min before induction. Propofol 1.0±1.5 mg.kg)1 was administered intravenously over 1 min until loss of eyelash re¯ex. Ventilation was assisted with 0.8±1.0% iso¯urane in oxygen. Cis-atracurium 0.15 mg.kg)1 or rocuronium Ó 2002 Blackwell Science Ltd

0.6 mg.kg-1 was used for facilitating tracheal intubation. Patients' lungs were ventilated with 60% N2O in oxygen using a circle system with CO2 absorber. Iso¯urane 0.6±1.2% was used to maintain adequate depth of anaesthesia. Mechanical ventilation was adjusted to maintain end-tidal CO2 at 4.5±5.0 kPa. Supplementary doses of opioids (half of the initial dose) were given when required, the last dose at least 30 min before wound closure. Increments of muscle relaxants were given if needed. A temperature probe was introduced into the nasopharynx after induction of anaesthesia. Ringer's solution was administered to compensate for the starvation period and thereafter according to surgical need. At the beginning of wound closure, 0.1 ml.kg)1 of blinded solution in a coded syringe was administered and the inhalational agent was discontinued. As our policy was prophylaxis, metoclopramide 10 mg was given simultaneously to prevent gastro-intestinal side-effects. Residual neuromuscular blockade was reversed using neostigmine and atropine. When respiration was adequate and the patient responded to verbal commands, the trachea was extubated. In the recovery room all patients were monitored and received oxygen via a face mask and were covered with a cotton blanket. An anaesthetist and recovery room nurse, both unaware of the test solution, observed the patient for shivering, sedation, pain, nausea, and vomiting and respiratory depression, the latter de®ned as a respiratory rate below 8 breath.min)1. A rescue dose of tramadol 50±100 mg was given either for shivering of grade ³ 2 (Table 1) or for pain. Patients were discharged after 30±45 min according to our recovery room protocol. Core temperature and ambient temperature were measured using the Passport Datascope. These temperatures were measured immediately after tracheal intubation, at the end of surgery and in the recovery room. Heart rate, blood pressure and oxygen saturation were monitored. Time of administration of test solution, reversal and tracheal extubation were noted to assess whether the test solution delayed the reversal. In the recovery room, temperature and vital signs were monitored. Shivering and sedation were assessed according to the grading shown in Table 1 Grading of shivering. Grade

Clinical signs

0 1

No shivering Mild fasciculations of face or neck and ECG disturbances in the absence of voluntary activity of the arms Visible tremor involving more than one muscle group Gross muscular activity involving the entire body

2 3

395


Tables 1 and 2. Patients were asked and ¤ or observed for pain and postoperative nausea and vomiting.

Table 4 Type of surgery.

Statistical analysis Statistical analyses were carried out using SPSS (Statistical Package for Social Sciences) windows version 9.0. Mean differences were tested using appropriate statistical tests such as ANOVA (in the case of more than two means). The difference among means was tested by Student's t-test in case of two groups. Paired t-test was used to test the difference between two observations in two time periods within cases. Chi-Squared test was used to test the difference between two proportions as well as to test the association between two proportions and to test the association between two categorical variables. A value of p < 0.05 was taken as signi®cant.

Type of surgery

High-dose group (n = 50)

Low-dose group Control (n = 50) (n = 50)

Laparoscopic-surgery Hernia repair Thyroidectomy Laparotomy Perianal surgery

22 9 3 10 6

23 13 3 6 5

Results

Demographic, anaesthetic and surgical variables were similar in all the groups (Tables 3 and 4). Heart rate, blood pressure and oxygen saturation showed no difference between the three groups (Table 5). Patients with core temperature less than 36 °C at various time intervals are represented in Table 6; core temperature reduction was in the range of 0.1±2.9 °C in all groups during the Table 2 Grading of sedation. Grades

Clinical signs

0 1 2 3 4

Alert Arouse to voice Arouse with gentle tactile stimulation Arouse with vigorous tactile stimulation No awareness

Table 3 Demographic, anaesthetic and surgical variables. Mean

(SD).

Variables Age; years Weight; kg Gender; M ¤ F Type of surgery; Laparoscopic ¤ open Duration of Anaesthesia; min Test solution to reversal; min Reversal to extubation; min

396


Low-dose group (n = 50)

Control (n = 50)

38.98 (11.85) 77.6 (14.2) 33 ¤ 17 30 ¤ 20

38.44 (12.68) 76.56 (15.91) 20 ¤ 30 22 ¤ 28

36.78 (11.55) 75.44 (18.16) 31 ¤ 19 23 ¤ 27

105.10 (43.87)

96.16 (31.77)

102.72 (41.8)

9.03 (7.02) 6.30 (3.56)

9.08 (5.79) 6.46 (2.84)

10.14 (6.63) 5.96 (2.56)

30 5 5 7 3

anaesthesia and recovery periods and no statistical differences were seen between the groups. The ambient temperature ranged from 21.2±24.9 °C. Shivering The incidence of shivering recorded in the recovery room is shown in Table 7. The core temperature remained very low (33.6 °C) in the single patient in the low-dose group with grade 3 shivering. Except for this case there was no relationship between magnitude of hypothermia and severity of shivering. Grade 3 shivering was seen in six patients in the control group. No statistical difference was seen between the high-dose and low-dose groups, but the incidence of shivering was signi®cantly lower in these groups when compared to the control group (p < 0.001). Sedation Sedation recorded in the recovery room is shown in Table 8. Between the high-dose and low-dose groups there was not a statistically signi®cant difference, but sedation in the high-dose group was signi®cantly more common compared to the control group (p < 0.005). None of the patients in any of the groups had undue sedation (grade 3 or 4). Respiratory depression did not occur in any patient and there was no signi®cant difference in time to tracheal extubation following reversal (Table 3). The use of rescue medication for either pain or shivering is shown in Table 9. As shivering was negligible in the high-dose and low-dose groups, medication was mainly indicated for pain in these groups and for shivering and pain in the control group. The use of rescue medication for shivering in the high- and low-dose groups was signi®cantly lower compared the control group (p < 0.001). After the ®rst rescue dose, no patient needed further doses during the recovery room stay. Side-effects Nausea and vomiting occurring during the recovery room stay is shown in Table 10. No statistically signi®cant difference was noted between groups. All patients Ó 2002 Blackwell Science Ltd


Table 5 Vital signs. Mean (SD). High-dose group (n = 50) Variable Heart rate Mean blood pressure SpO2

Low- dose group (n = 50)

Control (n = 50)

Preinduction

Post induction

Recovery

Preinduction

Postinduction

Recovery

Preinduction

Postinduction

Recovery

78.01 (12.64) 98.10 (10.45) 99.19 (0.89)

81.00 (13.73) 99.14 (10.85) 99.14 (0.85)

79.38 (12.82) 93.60 (10.96) 99.46 (1.19)

80.14 (11.12) 95.32 (12.15) 99.59 (1.26)

76.24 (12.11) 92.44 (15.08) 99.38 (1.01)

81.88 (15.35) 94.19 (10.98) 99.16 (1.50)

79.00 (12.81) 92.72 (10.81) 99.39 (1.92)

76.00 (13.93) 88.77 (12.81) 99.18 (1.05)

82.78 (15.43) 93.19 (14.24) 99.12 (1.18)

Table 6 Number of patients with temperature < 36 °C.

Post intubation Before extubation Recovery room



Control (n = 50)

20 31 36

28 33 41

20 27 32

No statistically signi®cant differences were found between the three groups.

Table 7 Shivering.

Table 9 Rescue medication.

Complaint

High- dose group (n = 50)


Control (n = 50)

Shivering Pain

0 5

1 11

14 14

Shivering: p < 0.001; High-dose vs. Control, Low-dose vs. Control. Pain: p < 0.05; High-dose vs. Control.

Table 10 Side-effects±nausea ¤ vomiting.

Grades of Shivering



Control (n = 50)

0 1 2 3 4

49 1 0 0 0

48 1 0 1 0

26 10 8 6 0

Complaints

High- dose group (n = 50)


Control (n = 50)

No nausea ¤ vomiting Nausea Vomiting ¤ retching

48 1 1

46 0 4

46 0 4

No statistically signi®cant difference between the three groups.

p < 0.001: High-dose vs. Control, Low-dose vs. Control. NS: High-dose vs. Low-dose.

Discussion Table 8 Sedation. Grades of Sedation

High-dose group (n 50)

Low- dose group (n 50)

Control (n 50)

0 1 2 3 4

11 33 6 0 0

22 24 4 0 0

32 15 3 0 0

p < 0.005: High-dose vs. Control.

in the three groups met the discharge criteria according to our recovery room protocol and were discharged 30± 45 min after arrival. Ó 2002 Blackwell Science Ltd

This study was designed to evaluate the ef®cacy of tramadol in preventing postanaesthetic shivering after a standardised anaesthetic regimen. Tramadol did not alter the time of extubation, sedation was not clinically or statistically signi®cant and there was no respiratory depression in any of the groups. There were no haemodynamic alterations throughout the period of anaesthesia or in the recovery room stay. Occasionally hypotension and orthostatic hypotension tend to occur with tramadol. This is secondary to peripheral vasodilation and can be minimised by injecting the drug slowly over minutes or by limiting the size of the bolus dose [9, 10]. Tramadol is an agonist at opioid receptors and has spinal and nervous system effects via adrenergic and 397


serotoninergic pathways [11], explaining the reduced tendency of tramadol to cause respiratory depression. This safety feature of tramadol compared to morphine or pethidine was shown in two studies by Vickers [12, 13]. Tramadol 3 mg.kg)1 was used by DeWitte et al. at wound closure and postoperative effects were analysed [6]. It was observed that shivering was totally abolished. However, no mention was made of side-effects such as nausea and vomiting in their study. Adverse effects, nausea in particular, are dose dependent and therefore considerably more likely to appear if the loading dose is high [14]. This can be minimised by slow injection and administration of prophylactic anti-emetics [15]. In the studies by Vickers [12, 13], there were no statistically signi®cant differences in the incidence of nausea or vomiting between tramadol and other opioids. This was further supported by Stamer in a patient-controlled analgesia study of tramadol and morphine [16]. Cagney and colleagues compared fentanyl to tramadol, and reported a similar incidence of side-effects for both [17]. Bhatnagar et al. treated postoperative shivering with tramadol or pethidine and found tramadol superior to pethidine without any incidence of respiratory depression. They used tramadol in a dose of 1 mg.kg-1 and found that 80% of patients stopped shivering within 10 min of administration of the drug [18]. In our series, the drug administered at wound closure may have achieved an effective concentration at the time of recovery. The overall incidence of emetic symptoms were very low, possibly due to the prophylactic use of metoclopramide. Due to the fear of cardio-respiratory depression there is a tendency to withhold opioid administration in the immediate postoperative period resulting in pain and shivering. In this study, tramadol appeared to be effective in the prevention and treatment of moderate to severe pain. Houmes has suggested using tramadol as the ®rst drug of choice for postoperative pain [19]. In conclusion, tramadol 2 mg.kg)1 or 1 mg.kg)1 administered at wound closure can effectively and safely prevent postanaesthetic shivering. References 1 Joris J, Banache M, Bonnet F, Sessler DI, Lamy M. Clonidine and ketanserin are both effective treatments for postanaesthetic shivering. Anesthesiology 1993; 79: 532±9.

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2 Horn E-P. Postoperative shivering. aetiology and treatment. Current Opinion in Anaesthesiology 1999; 12: 449±53. 3 Just B, Trevien V, Delva E, Lienhart A. Prevention of intraoperative hypothermia by preoperative skin-surface warming. Anesthesiolgy 1993; 79: 214±18. 4 Sessler DI. Temperature monitoring. In: Ronald, D Miller, eds. Anesthesia. London: Churchill Livingstone, 1994: 1363± 72. 5 De Witte J, Deloof T, De Veylder J, Housmans PR. Tramadol in the treatment of postanaesthetic shivering. Acta Anaesthesiologica Scandinavica 1997; 41: 506±10. 6 De Witte J, Rietman GW, Vandenbroucke G, Deloof T. Postoperative effects of tramadol administered at wound closure. Europeon Journal of Anaesthesiology 1998; 15: 190±5. 7 le Roux PJ, Coetzee JF. Tramadol today. Current Opinion in Anaesthesiology 2000; 13: 457±61. 8 Shipton EA. Tramadol- Present and Future. Anaesthesia and Intensive Care 2000; 28: 363±74. 9 Bamigbade TA, Langford RM. The Clinical use of tramadol hydrochloride. Pain Reviews 1998; 5: 155±82. 10 Lebedeva RN, Bondarenko AV, Abbakumov VV. Nikokda VV, Borisova IV. Karavaev Bl. Klimova El. Clinical use of tramal in patients in the early postoperative period. Anestezioliai Reanimatol Ogiia 1998; 5: 50±4. 11 Minto CF & Power I. New Opioid Analgesics: An Update. International Anaesthesiology Clinic 1997; 32: 49±50. 12 Vickers MD, O'Flaherty Szekely SM, Read M, Yoshizumi J. Tramadol: pain relief by an opioid without depression of respiration. Anaesthesia 1992; 47: 291±6. 13 Vickers MD, Paravicini D. Comparison of tramadol with morphine for postoperative pain following abdominal surgery. European Journal of Anaesthesiology 1995; 12: 265±71. 14 Dayer P, Desmeules J, Collart J. Pharmacology of tramadol. Drugs 1997; 53 (Suppl. 2): 18±24. 15 Lehmann KA. Tramadol in acute pain. Drugs 1997; 53 (Suppl. 2): 25±33. 16 Stamer UM, Maier C, Grond S, Veh-Schmidt B, Klaschik E, Lehmann KA. Tramadol in the management of postoperative pain: a double-blind, placebo ± and active drug-controlled study. European Journal of Anaesthesiology 1997; 14: 646±54. 17 Cagney B, Williams O, Jennings L, Buggy D. Tramadol or fentanyl analgesia for ambulatory knee arthroscopy. European Journal of Anaesthesiology 1999; 16: 182±5. 18 Bhatnagar S, Saxena A, Kannan TR, Punj J, Panigrahi M, Mishra S. Tramadol for post operative shivering: a Double blind comparison with pethidine. Anaesthesia and Intensive Care 2001; 29: 149±54. 19 Houmes RJ-M, Voets MA, Verkaaik A, Wilhelm E, Burkhard L. Efficacy and safety of tramadol versus morphine for moderate and severe postoperative pain with special regard to respiratory depression. Anesthesia and Analgesia 1992; 74: 510±14.



FORUM

The ef®cacy of lidocaine administered via the LITATM tracheal tube in attenuating the extubation response in beta-blocked patients following craniotomy* J. Andrzejowski and G. Francis Consultant Anaesthetists, Department of Anaesthesia, C Floor, Royal Hallamshire Hospital, Glossop Road, Shef®eld S10 2JF, UK Summary

The Laryngotracheal Instillation of Topical Anaesthetic (LITATM) tracheal tube has an additional pilot tube through which local anaesthetic can be instilled into the larynx via 10 small holes above and below the cuff. We studied 40 patients undergoing supratentorial craniotomy. They were premedicated with two oral doses of propranolol 1 mg.kg)1. The anaesthetic consisted of infusions of remifentanil, propofol and vecuronium. On insertion of the ®rst skin clip at the end of surgery, 5 ml of either saline or 2% lidocaine was injected into the appropriate lumen of the tracheal tube. There was no difference between the groups in the degree of coughing or the haemodynamic response to tracheal extubation. Keywords Equipment: tracheal tubes. Anaesthetics: local; lidocaine. Neurosurgery. Neurosurgical procedures: craniotomy. Adrenergic beta-antagonists. . ......................................................................................................

Correspondence to: Dr John Andrzejowski E-mail: [email protected] *Presented in part at the Neuroanaesthesia Society Annual Scienti®c Meeting, Cambridge; March 2001. Accepted: 9 November 2001

Unwelcome swings in blood pressure and intracranial pressure at the end of neurosurgical procedures are often secondary to the patient's waking with a tracheal tube in situ. Coughing further exacerbates these potentially dangerous physiological changes. It is well known that lidocaine can be used to suppress the haemodynamic responses to both intubation and extubation [1, 2]. We wanted to ascertain if, by anaesthetising the larynx before emergence from anaesthesia, these changes could be minimised. The Laryngotracheal Instillation of Topical Anaesthetic (LITATM) tracheal tube (Sheridan, Mass., USA) has an additional pilot tube through which local anaesthetic can be instilled via 10 small holes above and below the cuff (Fig. 1). It has been shown that with this tube, requirements for sedation are reduced in patients receiving intensive care, implying that its use effectively anaesthetises the pharynx ¤ larynx [3]. We studied beta-blocked patients, since this form of pre-


medication is routine in many neuroanaesthetic patients in our centre. Methods

Following approval by the Local Research Ethics Committee, written informed consent was obtained from 42 ASA 1-2 patients aged 18±80 years, due to undergo supratentorial craniotomy. Those with re¯ux disease or on antihypertensive medication were excluded. Patients were premedicated with 1 mg.kg)1 propranolol orally the night before, and again 90 min before, induction. The standardised anaesthetic technique consisted of controlled infusions of remifentanil (0.05±0.4 lg.kg)1.min)1) and propofol (target controlled, 2±5 lg.ml-1). These were titrated to maintain a systolic BP of 95±120 mmHg according to surgical requirements. A vecuronium infusion commencing at 0.1 mg.kg)1.h)1 was adjusted to

399


TM

Figure 1 The LITA

tube with saline exiting from 2 holes below the cuff and 8 holes above the cuff.

maintain less than one twitch on a peripheral nerve stimulator applied to the forearm. Tracheal intubation was with an 8-mm LITATM tracheal tube. Patients' lungs were ventilated to achieve normocarbia using an oxygen and air mix. Codeine phosphate 60 mg was administered intramuscularly 30 min before the end of surgery, and ¯uids given as required. Reversal of neuromuscular blockade was achieved with neostigmine and glycopyronium. Standard monitoring consisted of ECG, SpO2, direct monitoring of BP with an arterial line and measurement of end-expired carbon dioxide concentration. All haemodynamic data were downloaded, at 10-s intervals, to a computer for subsequent analysis. All aspects of anaesthetic care were unchanged for this trial in order to give the results maximum clinical signi®cance, so for example suctioning was carried out as necessary at the end of surgery. Coughing was assessed using a four point subjective scale: 0 none; 1 mild; 2 moderate; 3 severe. Randomisation was achieved using a sealed envelope technique. The study solution consisted of either 5 ml saline or 5 ml lidocaine 2%. Preparation of the solution was done by a second anaesthetist who was not involved in the case or in the assessment of patients. The solution was administered via the appropriate port of the LITATM tube on insertion of the ®rst skin clip at the end of surgery. Time to tracheal extubation was recorded from this point. Power analysis was based on a previous departmental audit and previous trials looking at haemodynamic changes at extubation. We calculated that to show a 25% difference in emergence blood pressures between the groups with a power of 80% and accepting p-values of < 0.05 as signi®cant, 40 patients would have to complete the trial. Data were analysed 400

using t-tests or Mann±Whitney U-test as appropriate, using SPSS v10.1. Results

Two patients were excluded from the analysis: in one, a throat pack was inadvertently inserted and in the second, the holes in the LITATM tube were blocked and it was impossible to inject the trial solution. In the saline group, three patients had surgery for epilepsy, eight had meningiomas removed, six had surgery for other space occupying lesions and three underwent clipping of aneurysms. In the lidocaine group, four patients had surgery for epilepsy, four had meningiomas removed, eight had surgery for other space occupying lesions and four underwent clipping of aneurysms. The groups were well matched in terms of age, weight and number of smokers (Table 1). Coincidentally, the ratio of males to females was reversed in the groups; there is no obvious reason for this chance ®nding. The duration Table 1 Characteristics of patients receiving lidocaine or saline

through the ÔLITATMÕ tracheal tube, duration of surgery and time to tracheal extubation. Values are mean (SD [range]) or number (proportion).

Males ¤ females Age; years Weight; kg Smokers Duration of surgery; min Time to extubation; min

Saline (n = 20)

Lidocaine (n = 20)

6 ¤ 14 46 (12 [23±66]) 74 (16 [51±100]) 11 (55%) 192 (57 [115±265]) 13 (5 [3±23])

12 ¤ 8 40 (12 [26±74]) 80 (21 [50±129]) 12 (60%) 195 (72 [120±425]) 13 (5 [3±30])



Table 2 Haemodynamic changes and

coughing scores after tracheal extubation in patients receiving lidocaine or saline through the ÔLITATMÕ tracheal tube. Values are mean (SD) or median (interquartile range [range]).

Saline (n = 20) 62 (12 [40±90) Pre-induction heart rate; beats.min)1 Peak heart rate after extubation; beats.min)1 80 (17 [50±110]) Pre-induction systolic BP; mmHg 131 (23 [89±181]) Peak systolic BP after extubation; mmHg 168 (26 [108±206]) Pre-induction diasolic BP; mmHg 81 (12 [58±107]) Peak diastolic BP after extubation; mmHg 92 (20 [48±142]) Coughing after extubation 1 (0±2 [0±2])

of surgery and the time to extubation following administration of the trial solution were similar in both groups. There were no statistical differences in haemodynamic changes or coughing scores between the groups (Table 2). There was no evidence of aspiration in any of the patients. Discussion

It is unknown what degree of haemodynamic change presents a true risk following neurosurgery. We have reported systolic pressure rather than mean arterial pressure since it is the potential rise in systolic pressure that could cause problems of a neurosurgical nature. This trial clearly demonstrated that signi®cant changes in pulse rate and blood pressure do occur during extubation, with pulse rate increasing 29%, systolic pressure increasing 28% and diastolic pressure increasing 14% in the saline group. Administration of lidocaine into the larynx and trachea did result in smaller changes, but this did not reach statistical signi®cance. We felt that the inclusion of a third group of patients in this study, to control for any systemic effect of the local anaesthetic, was unnecessary since intravenous levels following pharyngeal administration have been found to be very low (with peak levels only occurring after 30 min) even after doses 5±10 times greater than those used in this study [4, 5]. Our baseline pulse rate in beta-blocked patients was 62 beat.min)1 compared with 79 beat.min)1 in Shajar et al.'s study looking at non-beta-blocked patients during extubation [6]. Perhaps by studying a group of beta-blocked patients, in whom the haemodynamic response to extubation is already attenuated, a potential bene®t of the lidocaine was masked. The study needs to be repeated in a group of non-beta-blocked patients to see if any bene®t is seen using this technique. It is also possible that the administered local anaesthetic does not actually anaesthetise the area of mucosa directly in contact with the tracheal cuff. Since it is the stimulus of de¯ating the cuff that frequently causes coughing, this may be why greater differences were not seen between the groups. Using a more concentrated solution may have produced a positive result since a recently published study using 4% lidocaine administered through the LITATM Ó 2002 Blackwell Science Ltd

Lidocaine (n = 20) 62 78 132 158 78 82 1

(8 [52±80]) (9 [54±97]) (15 [109±169]) (23 [120±221]) (8 [65±94]) (12 [60±110]) (1±2 [0±3])

p-value

0.5 0.25 0.08 0.4

tube did show less coughing on emerging from an iso¯urane anaesthetic [7]. However, total intravenous anaesthesia is acknowledged to result in a smooth emergence from anaesthesia so perhaps it is not surprising that no difference in coughing was seen in our study. Since the degree of coughing on emergence was low, a much larger group would have to be studied to show a small difference using lidocaine down the LITATM tube. Acknowledgements

We would like to thank Dr A. Davidson and Dr J. Mundy for helping to recruit patients, Dr R. Freeman for his help with the computer software, and Dr J. Peacock for his statistical assistance. References 1 Kautto U-M, Heinonen J. Attenuation of circulatory response to laryngoscopy and tracheal intubation: a comparison of two methods of topical anaesthesia. Acta Anaethesiologica Scandinavica 1982; 26: 599±602. 2 Bidwai AV, Stanley TH, Bidwai VA. Blood pressure and pulse rate responses to extubation with and without prior topical tracheal anaesthesia. Canadian Anaesthetists' Society Journal 1978; 25: 416±18. 3 Mallick A, Smith SN, Bodenham AR. Local anaesthesia of the airway reduces sedation requirements in patients undergoing artificial ventilation. British Journal of Anaesthesia 1996; 77: 731±4. 4 Jakobsen CJ, Ahlburg P, Holdgard HO, Olsen KH, Thomsen A. Comparison of intravenous and topical lidocaine as a suppressant of coughing after bronchoscopy during general anesthesia. Acta Anaesthesiologica Scandinavica 1991; 35: 238±41. 5 Efthimiou J, Higenbottam T, Holt D, Cochrane GM. Plasma concentrations of lignocaine during fibreoptic bronchoscopy. Thorax 1982; 37: 68±71. 6 Shajar MA, Thompson JP, Hall AP, Leslie NA, Fox AJ. Effect of a remifentanil bolus dose on the cardiovascular response to emergence from anaesthesia and tracheal extubation. British Journal of Anaesthesia 1999; 83: 654±6. 7 Diachun CAB, Tunink BP, Brock-Utne JG. Suppression of cough during emergence from general anesthesia: laryngotracheal lidocaine through a modified endotracheal tube. Journal of Clinical Anesthesia 2001; 13: 447±51. 401


FORUM

The champagne angle P. L. Pemberton,1 I. Calder,2 C. O'Sullivan3 and H. A. Crockard4 1 Specialist Registrar in Anaesthesia, National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK 2 Consultant Anaesthetist, National Hospital for Neurology and Neurosurgery, Queen Square, London WC1N 3BG, UK 3 Medical Statistician, University College London Hospitals, Research and Development Directorate, 1st Floor, Vezey Strong Wing, 112 Hampstead Road, London NW1 2LT, UK 4 Professor of Surgical Neurology, National Hospital for Neurology and Neurosurgery, Queen Square London WC1N 3BG, UK Summary

A patient's observation led us to investigate whether drinking from a champagne ¯ute required more cranio-cervical extension than drinking from other types of wine glasses. We measured the cranio-cervical extension required by normal volunteers to drink from four different types of glass. The mean [95% con®dence intervals] extension from the neutral position required to drain each glass was: narrow ¯ute 40°[35±44]; wide ¯ute 22°[19-25]; wine glass 26°[24-29]; champagne saucer 0°[-1-2]. Drinking from the narrow rimmed champagne ¯ute required signi®cantly more extension than the other types of glass (p < 0.001), and 73% of the total available cranio-cervical extension. Keywords

Anatomy: neck movements.

. ......................................................................................................

Correspondence to: Dr P. L. Pemberton E-mail: [email protected] Accepted: 18 October 2001

We performed this study because a patient complained that, following an operation on her cervical spine, she could no longer drink comfortably from a champagne ¯ute. She had noticed that drinking champagne from a ¯ute required more neck extension than she now possessed. We investigated the amount of neck extension required to drink from a variety of wine glasses. Methods

After Local Research Ethics Committee approval, 25 volunteers (15 men and 10 women) gave verbal consent to inclusion in the study. All denied cervical spine problems. The volunteers were seated in a chair, so that movement of the spine was limited to the cervical region. A ÔneutralÕ cranio-cervical angle was determined by asking the volunteer to adopt what they regarded as their neutral position. The cranio-cervical angle was measured

402

by observing the angle formed between a line through the outer canthus of the eye and the tragus of the ear and the horizontal, using a bubble goniometer [1]. Each subject's maximum cranio-cervical extension was also measured. Ten ml of water were measured out into each of four different styles of wine glasses (Fig. 1). The volunteers were instructed to drink all the water using the minimum neck extension necessary to permit the passage of water from glass to mouth. The subjects were not allowed to propel the water towards the mouth by any mechanism other than tilting of the glass. The amount of craniocervical extension from the neutral position, the Ôdrain angleÕ that the subjects needed to drink from each of the wine glasses was measured. The total amount of extension from a horizontal, the Ôchampagne angleÕ, was calculated by summing the ÔneutralÕ angle and the ÔdrainÕ angle. The difference in cranio-cervical extension required to drain from each glass was compared using paired Student's



Table 1 Rim diameter and angles required to drain the glasses

studied. Values are mean[95% CI] where appropriate. Narrow ¯ute

Diameter of rim; cm Drain angle; degrees Champagne angle; degrees Champagne angle as proportion of maximum cranio-cervical extension;%

Wine glass

Wide ¯ute

Saucer

4.5 6.5 6.0 11.0 40[35-44] 26[24-29] 22[19-25] 0[-1-2] 59[54±63] 45[42±49] 41[38±44] 19[17±22] 73

56

51

24

All the glasses required signi®cantly different degrees of extension, p < 0.001.

Figure 1 Glasses used in study: a. Narrow ¯ute b. Wide ¯ute c.

Wine glass d. Champagne saucer.

t-tests with a Bonferroni adjustment to allow for multiple comparisons. The diameter of each glass at the rim was measured with a ruler. Results

The median [range] age of the volunteers was 37[25±53] years and their mean [95% con®dence interval] body mass index was 23[22±24] kg.m)2. The mean [95% CI] ÔneutralÕ angle was 19°[16°)21°] and the mean maximum cranio-cervical extension was 81°[76°)85°]. The largest ÔdrainÕ angle and Ôchampagne angleÕ were needed by the narrow ¯ute. The smallest angles were needed by the saucer. The results are given in Table 1. Discussion

The results of this study have vindicated our patient's observation. Draining a narrow champagne ¯ute requires signi®cantly more cranio-cervical extension than is needed to drain other types of glass. Our results suggest that patients who lose more than about 30% of their cranio-cervical extension may begin to encounter dif®culty when drinking from a narrow ¯ute. It is possible that the ability to drain a narrow ¯ute could be used as a simple test of neck extension. We believe that the principal difference between the glasses was how much tilt the subject could apply to the glass before the rim impinged on his or her face. The tilt that could be applied to the narrow champagne ¯ute was least because the rim impinged on the tip of most subjects' noses. The shape of the body of the glass is also important.


More tilt needs to be applied to drain Ôpot±belliedÕ glasses such as the narrow ¯ute and the wine glass. This factor probably explains our observation that the wine glass needed more cranio-cervical extension than the wide ¯ute, despite having a wider rim diameter. Whether dif®culty in drinking from narrow champagne ¯utes due to neck stiffness is actually a serious quality of life issue could be the basis of further research. We suspect that narrow champagne ¯utes are perceived as more elegant than wider ¯utes or saucers. Champagne saucers seem to have become unfashionable, but could be a welcome present for patients with stiff necks, since little, if any, extension is needed to drain them. Hosts may wish to consider this problem when serving champagne to an elderly gathering, as it is known that the mobility of the cervical spine decreases with age [2]. Drinking directly from the bottle requires little cranio-cervical extension, but we do not recommend this tactic. In our experience, a catastrophic breach of etiquette is almost inevitable, as rapid pharyngeal expansion of dissolved carbon dioxide tends to blow wine out of the nose. Acknowledgements

We thank our percipient patient, Mrs C. F., and Mr George Kaim, who took the photograph of the wine glasses. References 1 Horton WA, Fahy L, Charters P. Defining a standard intubating position using Ôangle finderÕ. British Journal of Anaesthesia 1989; 62: 6±12. 2 Castro WH, Sautmann A, Schilgen M, Sautmann M. Noninvasive three-dimensional analysis of cervical spine motion in normal subjects in relation to age and sex. An experimental examination. Spine 2000; 25: 443±9.

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