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General anaesthesia for day surgery:Preventing the problems
ARTICLE IN PRESS Current Anaesthesia & Critical Care (2007) 18, 188–192
www.elsevier.com/locate/cacc
FOCUS ON: DAY CASE
General anaesthesia for day surgery: Preventing the problems Sarah Lloyd Department of Anaesthesia, St James University Hospital, Becket Street, Leeds, LS9 7TF, UK
KEYWORDS Intravenous anaesthesia; Propofol; Inhalation anaesthesia; Desflurane; Sevoflurane; Laryngeal mask airway
Summary The ideal day case anaesthetic should provide a rapid and smooth induction with good operating conditions, rapid recovery and minimal postoperative complications. No current agent is ideal, but careful use of the available choices can still produce excellent results. No single technique has been shown to give consistently superior recovery and achieving optimal results relies on a combination of factors, including provision of effective non-opioid analgesia, use of supplemental fluids, minimising emetogenic supplements and careful titration of anaesthesia to effect. The art and skill of the individual anaesthetist are as important in this respect as their actual choice of anaesthetic drugs. & 2007 Published by Elsevier Ltd.
Introduction The essential characteristics of good day case anaesthesia are that it should be safe, with a pleasant induction and high quality surgical conditions, rapid recovery and few postoperative problems. It also needs to be cost-effective and to promote efficient patient flow.
The ideal day case anaesthetic The triad of general anaesthesia consisting of hypnosis, analgesia and muscle relaxation was first described using a single agent. Modern balanced anaesthesia uses a combination of drugs to achieve this triad, although the use of a single agent, or at E-mail address: [email protected] 0953-7112/$ - see front matter & 2007 Published by Elsevier Ltd. doi:10.1016/j.cacc.2007.07.002
least a greatly reduced number of agents, is gaining in popularity.1 Patients undergoing day surgery expect high quality, rapid onset of anaesthesia and a problem-free recovery, therefore the choice of agents and techniques and the way they are employed are of great importance.
Preoperative medication Premedication for anxiolysis, using drugs such as benzodiazepines, is not commonly employed in adult day surgical practice, as the effects of these drugs may continue into the postoperative period impairing recovery. While there is no evidence to suggest that pharmacological anxiolysis delays discharge from hospital,1 impairment on psychomotor testing in the postoperative period has been shown.
ARTICLE IN PRESS General anaesthesia for day surgery
189
Preoperative anxiety is commonly managed nonpharmacologically within the day care environment. Patients and their carers are well informed about all aspects of their care, using pre-prepared literature. Medical and nursing staff take time to explain procedures and answer questions. The flow of patients through the unit may be designed to minimise waiting times as much as possible and many patients find distraction in the form of watching television, listening to music or reading useful. There is often flexibility to change the list order so that especially anxious patients, or those with special needs, are brought forward. However, pharmacological anxiolysis should not be withheld if it is considered to be beneficial in selected cases. Other drugs may be indicated in the preoperative period, including prophylaxis of acid reflux in susceptible patients and paracetamol or nonsteroidal antiinflammatory drugs (NSAIDs) as part of an analgesic strategy.
Induction of anaesthesia Propofol is the intravenous induction agent of choice for day surgery and is used for this purpose by the majority of anaesthetists in the UK. It achieves smooth and rapid loss of consciousness with few side effects. Pain on injection is less common with newer preparations and is greatly reduced by the addition of lidocaine. Propofol induction results in marked respiratory depression and obtunds the airway reflexes; this can be useful in rapidly achieving control of the airway. Inhalational induction using sevoflurane is an alternative method of induction of anaesthesia. The use of a vital capacity technique with a circuit primed with 8% sevoflurane in 75% nitrous oxide produced a faster loss of consciousness compared to propofol induction,2 but with similar side effects, recovery times and patient satisfaction. Tidal breathing techniques, in which 8% sevoflurane is inspired from the outset, are simpler to use and still give excellent results in most cases.3 Inhalation induction is used regularly by some anaesthetists,
but enjoys more widespread occasional usage for paediatric patients and adults with anxiety or a phobia of needles. However, the technique probably deserves wider use and has been shown to be more popular with patients than many anaesthetists believe.4 Rapid sequence induction may need to be employed for patients at especially high risk of gastro-oesophageal reflux; such cases are being encountered more commonly in day surgery as obese patients and those with significant comorbidities are no longer excluded. Other induction agents have no real place in day case anaesthesia, since they are associated with too prolonged a recovery or an unacceptable incidence of postoperative nausea and vomiting (PONV).
Maintenance of anaesthesia The choice of maintenance technique needs to be based on combining optimal surgical conditions with rapid recovery and a low incidence of problems, such as poor analgesia or PONV. The techniques available consist of using inhalational or intravenous agents or a combination of these with or without concomitant use of nitrous oxide (N2O).
Inhalational agents Halothane and enflurane, although widely used in the past, are now rarely employed in anaesthesia for day surgery in the UK. In practice, the choice of inhalational agents rests between isoflurane, sevoflurane and desflurane, and some of their properties are shown in Table 1. An ideal agent would have a low blood /gas partition coefficient, ensuring rapid uptake, good controllability and fast recovery, be sufficiently potent with a high oil/ gas partition coefficient and low MAC to allow it to be used with enhanced oxygen concentrations and N2O and be excreted without metabolism (or harmful metabolites). Other factors influencing choice of agents include an irritant effect on airways with isoflurane
Table 1 Comparison of some physical properties of the inhaled agents most commonly used in day case anaesthesia. Agent
Isoflurane Sevoflurane Desflurane N2O
Partition coefficient Blood/gas
Oil/gas
1.4 0.69 0.42 0.47
97 53 19 1.4
MAC (adults) (%)
Metabolism (%)
1–1.2 1.4–2.5 5–7 105
0.2 o5 0.02 0
ARTICLE IN PRESS 190 and desflurane, making inhalational induction very difficult and the requirement of special equipment in the form of a direct metering vaporiser for desflurane. There are significant differences in cost between agents, with sevoflurane and desflurane being more expensive than isoflurane, however this differential has been reduced as generic preparations become available. Nitrous oxide Nitrous oxide is widely used as an adjunct to more potent anaesthetics, contributing to improved cardio-respiratory stability, rapid emergence and a reduced incidence of awareness.5 It may increase the incidence of PONV where the risk is high and should not be used in circumstances where expansion of air filled spaces (due to the more rapid diffusion of nitrous oxide than nitrogen) may be a problem. Use of nitrous oxide reduces the requirement for the more potent and expensive volatile agents and therefore influences the cost of anaesthesia. Intravenous anaesthesia Propofol has a pharmacokinetic profile that is well suited to day case anaesthesia, as it provides rapid recovery due to its short redistribution (1–2 min) and elimination (1–5 h) half lives. Propofol can be used by infusion for the maintenance of anaesthesia, either with nitrous oxide or as total intravenous anaesthesia (TIVA), where the patient breathes oxygen in air and a short acting analgesic, such as alfentanil or remifentanil, provides analgesia. Infusion techniques using propofol require that the rate is adjusted to maintain plasma concentrations and therefore depth of anaesthesia. The infusion rate can be controlled using a manual regime or by utilising a computer controlled pump. A target controlled infusion (TCI) utilises an algorithm to deliver a chosen plasma concentration to the patient and adjusts the pump to maintain that concentration as redistribution and elimination occur. A commercial system is available (Diprifusors), but this requires the use of special pre-filled syringes that adds to the expense of this technique. Generic forms of TCI, which can be used with any form of propofol, will address this issue and are now available in parts of Europe. There is debate as to whether the use of TCI is superior to manual control in delivering a constant depth of anaesthesia, but the former is somewhat easier to use. Analgesia A balanced multimodal approach should be employed with the aim of producing good intra- and
S. Lloyd postoperative pain control with minimal side effects. Local anaesthetic infiltration (or nerve blocks) may be undertaken before surgical stimulus, this may reduce the amount of opiates required postoperatively and thus their associated morbidity, while the total amount of inhalational or intravenous anaesthetic may also be reduced, leading to quicker emergence. Paracetamol or NSAIDs can be given by mouth preoperatively and will contribute to analgesic requirements in the early postoperative period. For all but the most minor procedures, it is common to use an opioid (particularly fentanyl) as part of the anaesthetic technique to improve intraoperative conditions and in the assumption that it will contribute to postoperative analgesia. Adequate intraoperative conditions can usually be achieved by small increases in the anaesthetic concentration, while local anaesthetic wound infiltration and NSAIDs provide good postoperative analgesia. Fentanyl does not improve postoperative pain control, although it does produce a significant increase in the incidence and severity of PONV.6–8 The use of intraoperative morphine is likely to be even worse. Opioid supplements are more likely to be used in conjunction with intravenous anaesthesia, where the antiemetic effect of propofol will reduce their potential for PONV. Alfentanil and more recently remifentanil9 show favourable recovery characteristics when used as an infusion as part of TIVA. In using infusions of ultra-short acting drugs, such as remifentanil, it is essential to plan analgesia for the immediate postoperative period in order to prevent pain being a problem in the recovery room. Even remifentanil can increase PONV and the short-acting beta blocker, esmolol, has been used as an alternative to control cardiovascular stability.10 Muscle relaxation For many day case procedures, formal muscle relaxation using neuromuscular blocking drugs is not necessary. As the scope of day surgery increases, however, more procedures requiring muscle relaxation are being undertaken. The use of the depolarising muscle relaxant succinylcholine (suxamethonium) has a place where a rapid sequence induction is indicated; however, its side effect profile—in particular muscle pains— may be a problem in day case patients. Rocuronium may be a reasonable alternative if difficult intubation is thought to be unlikely. The choices of nondepolarising muscle relaxant will depend on the anticipated duration of surgery and whether reversal is planned. Reversal of non-depolarising
ARTICLE IN PRESS General anaesthesia for day surgery muscle relaxants with neostigmine has been implicated in causing PONV, although a recent review suggests that its use does not increase PONV during the first 24 h after surgery.11 Tracheal intubation can also be achieved without muscle relaxants after an induction dose of propofol combined with fentanyl, alfentanil or remifentanil or under deep inhalation anaesthesia. Airway and ventilation A large proportion of day case procedures are managed using the laryngeal mask airway (LMA) with spontaneous or mechanical ventilation. There is good experience of the LMA in a wide variety of situations. The use of a LMA gives protection from soiling of the trachea from above, which is important for dental or nasal procedures. It does not protect against the aspiration of regurgitated stomach contents, however. Tracheal intubation leads to increased complaints of postoperative sore throat, also the time taken for the anaesthetist to extubate patients may add to the ‘turn around’ time between cases. There are now a vast profusion of new supraglottic airways which are intended as an alternative to the LMA. To date, none have any obvious advantage over the well-established LMA.
Comparison of techniques Recovery characteristics There are no standard tests for assessing recovery from anaesthesia; clinical assessment is used in routine practice, with more sophisticated tests being reserved for studies comparing anaesthetic techniques. In day surgical practice there are three times that are of particular interest; the time of emergence from anaesthesia—identified by eye opening or obeying commands; the time the patient is fit to leave the postanaesthetic care unit (PACU) and the time they are fit to be discharged home. Actual time to discharge home is a poor indicator, as this may be affected by practical considerations, such as the availability of an escort or transport arrangements. A recent meta-analysis compared the recovery profiles of propofol, isoflurane, sevoflurane and desflurane.12 Emergence times were similar after isoflurane and propofol, a little faster after sevoflurane and fastest of all after desflurane, although the actual differences were no more than 1–2 min, with a lot of variability between individual studies. Later recovery endpoints seemed to differ even less between the various agents, although isoflurane appeared to result in a delay of approximately
191 15 min in home-readiness.12 The clinical significance of any of these differences is doubtful, however. It is important to also consider the effect of the anaesthetic technique on problems encountered during the first 24 h after surgery when PONV, pain, drowsiness, somnolence, dizziness, headache and sore throat may all be unpleasant for day case patients. Patients receiving propofol for the maintenance of anaesthesia had a lower incidence of PONV compared to those managed with techniques including inhalational agents13 and the requirement for antiemetic therapy was also somewhat reduced.12 However, the clinical significance of the late antiemetic effect of propofol has been questioned.14 Practitioners using inhalation-based anaesthesia probably need to take more care in order to reduce PONV to acceptable levels, such as by the avoidance of opioids and, perhaps, the use of prophylactic antiemetics. Administering as little as one litre of intravenous fluid is also a simple and inexpensive way of significantly reducing PONV, dizziness and somnolence in the first 24 h after surgery.15
Cost effectiveness and efficiency The benefits of reduced recovery times can only be translated into cost savings if either staff numbers can be reduced or more patients can be treated by the existing team. There may also be additional cost implications for techniques where specialist equipment is required, for instance infusion devices for TIVA or TCI, or new vaporisers for inhaled anaesthetics. Comparison of the costs of drugs depends not only on the amount used but also any wastage that may occur, for example with TIVA techniques unused drug is discarded in the syringe at the end of each case.16 Bypassing the PACU, by transferring patients directly to the second level recovery or ward facility (‘‘fast tracking’’), is advocated as a method of cost saving in some centres in the USA. In one study, 90% of patients receiving desflurane and 75% of those receiving sevoflurane met the criteria for fast tracking compared to only 25% after propofol, suggesting the recovery characteristics of the newer volatile anaesthetics to be superior in this context.17 However, others have failed to detect such great differences and it is likely that there may be only very limited benefit to fast track recovery in the UK.18 Efficiency in day surgical theatres also depends on minimising the time between cases and this ‘‘turnover time’’ may vary with different techniques.
ARTICLE IN PRESS 192
S. Lloyd
Conclusions No single anaesthetic technique has been shown to be clearly superior for day case surgery, therefore the choice of technique must take other factors into account. The experience of the anaesthetist using a given technique is important and a learning curve showing improvements in recovery times and the incidence of side effects has been identified,19 even when a standard protocol is used. The availability of equipment and other factors in the environment in which anaesthesia is to be delivered may make some techniques more suitable for certain circumstances. In addition to the advances in ‘science’ with new drugs and delivery systems, the practice of the ‘art’ of anaesthesia is still important to deliver the very best quality care for our patients.
References 1. Smith AF, Pittaway AJ. Premedication for anxiety in adult day surgery. Cochrane Database Syst Rev 2000(3):CD002192. 2. Philip BK, Lombard LL, Roaf ER, Drager LR, Calalang I, Philip JH. Comparison of vital capacity induction with sevoflurane to intravenous induction with propofol for adult ambulatory anesthesia. Anesth Analg 1999;89(3):623–7. 3. Ghatge S, Lee J, Smith I. Sevoflurane: an ideal agent for adult day-case anesthesia? Acta Anaesthesiol Scand 2003; 47(8):917–31. 4. van den Berg AA, Chitty DA, Jones RD, Sohel MS, Shahen A. Intravenous or inhaled induction of anesthesia in adults? An audit of preoperative patient preferences. Anesth Analg 2005;100(5):1422–4. 5. Hopkins PM. Nitrous oxide: a unique drug of continuing importance for anaesthesia. Best Pract Res Clin Anaesthesiol 2005;19(3):381–9. 6. Shakir AAK, Ramachandra V, Hasan MA. Day surgery postoperative nausea and vomiting at home related to peroperative fentanyl. J One-day Surg 1997;6(3):10–1. 7. Smith I. Avoidance of fentanyl reduces nausea and vomiting associated with volatile induction and maintenance of
8.
9.
10.
11.
12.
13.
14.
15.
16. 17.
18.
19.
anaesthesia with sevoflurane (abstract). Anaesthesia 2007; 62:309. Sukhani R, Vazquez J, Pappas AL, Frey K, Aasen M, Slogoff S. Recovery after propofol with and without intraoperative fentanyl in patients undergoing ambulatory gynecologic laparoscopy. Anesth Analg 1996;83(5):975–81. Cartwright DP, Kvalsvik O, Cassuto J, Jansen JP, Wall C, Remy B, et al. A randomized, blind comparison of remifentanil and alfentanil during anesthesia for outpatient surgery. Anesth Analg 1997;85(5):1014–9. Coloma M, Chiu JW, White PF, Armbruster SC. The use of esmolol as an alternative to remifentanil during desflurane anesthesia for fast-track outpatient gynecologic laparoscopic surgery. Anesth Analg 2001;92(2):352–7. Cheng CR, Sessler DI, Apfel CC. Does neostigmine administration produce a clinically important increase in postoperative nausea and vomiting? Anesth Analg 2005;101(5): 1349–55. Gupta A, Stierer T, Zuckerman R, Sakima N, Parker SD, Fleisher LA. Comparison of recovery profile after ambulatory anesthesia with propofol, isoflurane, sevoflurane and desflurane: a systematic review. Anesth Analg 2004;98(3): 632–41. Sneyd JR, Carr A, Byrom WD, Bilski AJ. A meta-analysis of nausea and vomiting following maintenance of anaesthesia with propofol or inhalational agents. Eur J Anaesthesiol 1998;15(4):433–45. Tramer M, Moore A, McQuay H. Meta-analytic comparison of prophylactic antiemetic efficacy for postoperative nausea and vomiting: propofol anaesthesia vs omitting nitrous oxide vs total i.v. anaesthesia with propofol. Br J Anaesth 1997; 78(3):256–9. Yogendran S, Asokumar B, Cheng DC, Chung F. A prospective randomized double-blinded study of the effect of intravenous fluid therapy on adverse outcomes on outpatient surgery. Anesth Analg 1995;80(4):682–6. Smith I. Cost considerations in the use of anaesthetic drugs. Pharmacoeconomics 2001;19(5 Pt 1):469–81. Song D, Joshi GP, White PF. Fast-track eligibility after ambulatory anesthesia: a comparison of desflurane, sevoflurane, and propofol. Anesth Analg 1998;86(2):267–73. Millar II. J. Fast-tracking in day surgery. Is your journey to the recovery room really necessary? Br J Anaesth 2004; 93(6):756–8. Joshi GP, Jamerson BD, Roizen MF, Fleisher L, Twersky RS, et al. Is there a learning curve associated with the use of remifentanil? Anesth Analg 2000;91(5):1049–55.
www.elsevier.com/locate/cacc
FOCUS ON: DAY CASE
General anaesthesia for day surgery: Preventing the problems Sarah Lloyd Department of Anaesthesia, St James University Hospital, Becket Street, Leeds, LS9 7TF, UK
KEYWORDS Intravenous anaesthesia; Propofol; Inhalation anaesthesia; Desflurane; Sevoflurane; Laryngeal mask airway
Summary The ideal day case anaesthetic should provide a rapid and smooth induction with good operating conditions, rapid recovery and minimal postoperative complications. No current agent is ideal, but careful use of the available choices can still produce excellent results. No single technique has been shown to give consistently superior recovery and achieving optimal results relies on a combination of factors, including provision of effective non-opioid analgesia, use of supplemental fluids, minimising emetogenic supplements and careful titration of anaesthesia to effect. The art and skill of the individual anaesthetist are as important in this respect as their actual choice of anaesthetic drugs. & 2007 Published by Elsevier Ltd.
Introduction The essential characteristics of good day case anaesthesia are that it should be safe, with a pleasant induction and high quality surgical conditions, rapid recovery and few postoperative problems. It also needs to be cost-effective and to promote efficient patient flow.
The ideal day case anaesthetic The triad of general anaesthesia consisting of hypnosis, analgesia and muscle relaxation was first described using a single agent. Modern balanced anaesthesia uses a combination of drugs to achieve this triad, although the use of a single agent, or at E-mail address: [email protected] 0953-7112/$ - see front matter & 2007 Published by Elsevier Ltd. doi:10.1016/j.cacc.2007.07.002
least a greatly reduced number of agents, is gaining in popularity.1 Patients undergoing day surgery expect high quality, rapid onset of anaesthesia and a problem-free recovery, therefore the choice of agents and techniques and the way they are employed are of great importance.
Preoperative medication Premedication for anxiolysis, using drugs such as benzodiazepines, is not commonly employed in adult day surgical practice, as the effects of these drugs may continue into the postoperative period impairing recovery. While there is no evidence to suggest that pharmacological anxiolysis delays discharge from hospital,1 impairment on psychomotor testing in the postoperative period has been shown.
ARTICLE IN PRESS General anaesthesia for day surgery
189
Preoperative anxiety is commonly managed nonpharmacologically within the day care environment. Patients and their carers are well informed about all aspects of their care, using pre-prepared literature. Medical and nursing staff take time to explain procedures and answer questions. The flow of patients through the unit may be designed to minimise waiting times as much as possible and many patients find distraction in the form of watching television, listening to music or reading useful. There is often flexibility to change the list order so that especially anxious patients, or those with special needs, are brought forward. However, pharmacological anxiolysis should not be withheld if it is considered to be beneficial in selected cases. Other drugs may be indicated in the preoperative period, including prophylaxis of acid reflux in susceptible patients and paracetamol or nonsteroidal antiinflammatory drugs (NSAIDs) as part of an analgesic strategy.
Induction of anaesthesia Propofol is the intravenous induction agent of choice for day surgery and is used for this purpose by the majority of anaesthetists in the UK. It achieves smooth and rapid loss of consciousness with few side effects. Pain on injection is less common with newer preparations and is greatly reduced by the addition of lidocaine. Propofol induction results in marked respiratory depression and obtunds the airway reflexes; this can be useful in rapidly achieving control of the airway. Inhalational induction using sevoflurane is an alternative method of induction of anaesthesia. The use of a vital capacity technique with a circuit primed with 8% sevoflurane in 75% nitrous oxide produced a faster loss of consciousness compared to propofol induction,2 but with similar side effects, recovery times and patient satisfaction. Tidal breathing techniques, in which 8% sevoflurane is inspired from the outset, are simpler to use and still give excellent results in most cases.3 Inhalation induction is used regularly by some anaesthetists,
but enjoys more widespread occasional usage for paediatric patients and adults with anxiety or a phobia of needles. However, the technique probably deserves wider use and has been shown to be more popular with patients than many anaesthetists believe.4 Rapid sequence induction may need to be employed for patients at especially high risk of gastro-oesophageal reflux; such cases are being encountered more commonly in day surgery as obese patients and those with significant comorbidities are no longer excluded. Other induction agents have no real place in day case anaesthesia, since they are associated with too prolonged a recovery or an unacceptable incidence of postoperative nausea and vomiting (PONV).
Maintenance of anaesthesia The choice of maintenance technique needs to be based on combining optimal surgical conditions with rapid recovery and a low incidence of problems, such as poor analgesia or PONV. The techniques available consist of using inhalational or intravenous agents or a combination of these with or without concomitant use of nitrous oxide (N2O).
Inhalational agents Halothane and enflurane, although widely used in the past, are now rarely employed in anaesthesia for day surgery in the UK. In practice, the choice of inhalational agents rests between isoflurane, sevoflurane and desflurane, and some of their properties are shown in Table 1. An ideal agent would have a low blood /gas partition coefficient, ensuring rapid uptake, good controllability and fast recovery, be sufficiently potent with a high oil/ gas partition coefficient and low MAC to allow it to be used with enhanced oxygen concentrations and N2O and be excreted without metabolism (or harmful metabolites). Other factors influencing choice of agents include an irritant effect on airways with isoflurane
Table 1 Comparison of some physical properties of the inhaled agents most commonly used in day case anaesthesia. Agent
Isoflurane Sevoflurane Desflurane N2O
Partition coefficient Blood/gas
Oil/gas
1.4 0.69 0.42 0.47
97 53 19 1.4
MAC (adults) (%)
Metabolism (%)
1–1.2 1.4–2.5 5–7 105
0.2 o5 0.02 0
ARTICLE IN PRESS 190 and desflurane, making inhalational induction very difficult and the requirement of special equipment in the form of a direct metering vaporiser for desflurane. There are significant differences in cost between agents, with sevoflurane and desflurane being more expensive than isoflurane, however this differential has been reduced as generic preparations become available. Nitrous oxide Nitrous oxide is widely used as an adjunct to more potent anaesthetics, contributing to improved cardio-respiratory stability, rapid emergence and a reduced incidence of awareness.5 It may increase the incidence of PONV where the risk is high and should not be used in circumstances where expansion of air filled spaces (due to the more rapid diffusion of nitrous oxide than nitrogen) may be a problem. Use of nitrous oxide reduces the requirement for the more potent and expensive volatile agents and therefore influences the cost of anaesthesia. Intravenous anaesthesia Propofol has a pharmacokinetic profile that is well suited to day case anaesthesia, as it provides rapid recovery due to its short redistribution (1–2 min) and elimination (1–5 h) half lives. Propofol can be used by infusion for the maintenance of anaesthesia, either with nitrous oxide or as total intravenous anaesthesia (TIVA), where the patient breathes oxygen in air and a short acting analgesic, such as alfentanil or remifentanil, provides analgesia. Infusion techniques using propofol require that the rate is adjusted to maintain plasma concentrations and therefore depth of anaesthesia. The infusion rate can be controlled using a manual regime or by utilising a computer controlled pump. A target controlled infusion (TCI) utilises an algorithm to deliver a chosen plasma concentration to the patient and adjusts the pump to maintain that concentration as redistribution and elimination occur. A commercial system is available (Diprifusors), but this requires the use of special pre-filled syringes that adds to the expense of this technique. Generic forms of TCI, which can be used with any form of propofol, will address this issue and are now available in parts of Europe. There is debate as to whether the use of TCI is superior to manual control in delivering a constant depth of anaesthesia, but the former is somewhat easier to use. Analgesia A balanced multimodal approach should be employed with the aim of producing good intra- and
S. Lloyd postoperative pain control with minimal side effects. Local anaesthetic infiltration (or nerve blocks) may be undertaken before surgical stimulus, this may reduce the amount of opiates required postoperatively and thus their associated morbidity, while the total amount of inhalational or intravenous anaesthetic may also be reduced, leading to quicker emergence. Paracetamol or NSAIDs can be given by mouth preoperatively and will contribute to analgesic requirements in the early postoperative period. For all but the most minor procedures, it is common to use an opioid (particularly fentanyl) as part of the anaesthetic technique to improve intraoperative conditions and in the assumption that it will contribute to postoperative analgesia. Adequate intraoperative conditions can usually be achieved by small increases in the anaesthetic concentration, while local anaesthetic wound infiltration and NSAIDs provide good postoperative analgesia. Fentanyl does not improve postoperative pain control, although it does produce a significant increase in the incidence and severity of PONV.6–8 The use of intraoperative morphine is likely to be even worse. Opioid supplements are more likely to be used in conjunction with intravenous anaesthesia, where the antiemetic effect of propofol will reduce their potential for PONV. Alfentanil and more recently remifentanil9 show favourable recovery characteristics when used as an infusion as part of TIVA. In using infusions of ultra-short acting drugs, such as remifentanil, it is essential to plan analgesia for the immediate postoperative period in order to prevent pain being a problem in the recovery room. Even remifentanil can increase PONV and the short-acting beta blocker, esmolol, has been used as an alternative to control cardiovascular stability.10 Muscle relaxation For many day case procedures, formal muscle relaxation using neuromuscular blocking drugs is not necessary. As the scope of day surgery increases, however, more procedures requiring muscle relaxation are being undertaken. The use of the depolarising muscle relaxant succinylcholine (suxamethonium) has a place where a rapid sequence induction is indicated; however, its side effect profile—in particular muscle pains— may be a problem in day case patients. Rocuronium may be a reasonable alternative if difficult intubation is thought to be unlikely. The choices of nondepolarising muscle relaxant will depend on the anticipated duration of surgery and whether reversal is planned. Reversal of non-depolarising
ARTICLE IN PRESS General anaesthesia for day surgery muscle relaxants with neostigmine has been implicated in causing PONV, although a recent review suggests that its use does not increase PONV during the first 24 h after surgery.11 Tracheal intubation can also be achieved without muscle relaxants after an induction dose of propofol combined with fentanyl, alfentanil or remifentanil or under deep inhalation anaesthesia. Airway and ventilation A large proportion of day case procedures are managed using the laryngeal mask airway (LMA) with spontaneous or mechanical ventilation. There is good experience of the LMA in a wide variety of situations. The use of a LMA gives protection from soiling of the trachea from above, which is important for dental or nasal procedures. It does not protect against the aspiration of regurgitated stomach contents, however. Tracheal intubation leads to increased complaints of postoperative sore throat, also the time taken for the anaesthetist to extubate patients may add to the ‘turn around’ time between cases. There are now a vast profusion of new supraglottic airways which are intended as an alternative to the LMA. To date, none have any obvious advantage over the well-established LMA.
Comparison of techniques Recovery characteristics There are no standard tests for assessing recovery from anaesthesia; clinical assessment is used in routine practice, with more sophisticated tests being reserved for studies comparing anaesthetic techniques. In day surgical practice there are three times that are of particular interest; the time of emergence from anaesthesia—identified by eye opening or obeying commands; the time the patient is fit to leave the postanaesthetic care unit (PACU) and the time they are fit to be discharged home. Actual time to discharge home is a poor indicator, as this may be affected by practical considerations, such as the availability of an escort or transport arrangements. A recent meta-analysis compared the recovery profiles of propofol, isoflurane, sevoflurane and desflurane.12 Emergence times were similar after isoflurane and propofol, a little faster after sevoflurane and fastest of all after desflurane, although the actual differences were no more than 1–2 min, with a lot of variability between individual studies. Later recovery endpoints seemed to differ even less between the various agents, although isoflurane appeared to result in a delay of approximately
191 15 min in home-readiness.12 The clinical significance of any of these differences is doubtful, however. It is important to also consider the effect of the anaesthetic technique on problems encountered during the first 24 h after surgery when PONV, pain, drowsiness, somnolence, dizziness, headache and sore throat may all be unpleasant for day case patients. Patients receiving propofol for the maintenance of anaesthesia had a lower incidence of PONV compared to those managed with techniques including inhalational agents13 and the requirement for antiemetic therapy was also somewhat reduced.12 However, the clinical significance of the late antiemetic effect of propofol has been questioned.14 Practitioners using inhalation-based anaesthesia probably need to take more care in order to reduce PONV to acceptable levels, such as by the avoidance of opioids and, perhaps, the use of prophylactic antiemetics. Administering as little as one litre of intravenous fluid is also a simple and inexpensive way of significantly reducing PONV, dizziness and somnolence in the first 24 h after surgery.15
Cost effectiveness and efficiency The benefits of reduced recovery times can only be translated into cost savings if either staff numbers can be reduced or more patients can be treated by the existing team. There may also be additional cost implications for techniques where specialist equipment is required, for instance infusion devices for TIVA or TCI, or new vaporisers for inhaled anaesthetics. Comparison of the costs of drugs depends not only on the amount used but also any wastage that may occur, for example with TIVA techniques unused drug is discarded in the syringe at the end of each case.16 Bypassing the PACU, by transferring patients directly to the second level recovery or ward facility (‘‘fast tracking’’), is advocated as a method of cost saving in some centres in the USA. In one study, 90% of patients receiving desflurane and 75% of those receiving sevoflurane met the criteria for fast tracking compared to only 25% after propofol, suggesting the recovery characteristics of the newer volatile anaesthetics to be superior in this context.17 However, others have failed to detect such great differences and it is likely that there may be only very limited benefit to fast track recovery in the UK.18 Efficiency in day surgical theatres also depends on minimising the time between cases and this ‘‘turnover time’’ may vary with different techniques.
ARTICLE IN PRESS 192
S. Lloyd
Conclusions No single anaesthetic technique has been shown to be clearly superior for day case surgery, therefore the choice of technique must take other factors into account. The experience of the anaesthetist using a given technique is important and a learning curve showing improvements in recovery times and the incidence of side effects has been identified,19 even when a standard protocol is used. The availability of equipment and other factors in the environment in which anaesthesia is to be delivered may make some techniques more suitable for certain circumstances. In addition to the advances in ‘science’ with new drugs and delivery systems, the practice of the ‘art’ of anaesthesia is still important to deliver the very best quality care for our patients.
References 1. Smith AF, Pittaway AJ. Premedication for anxiety in adult day surgery. Cochrane Database Syst Rev 2000(3):CD002192. 2. Philip BK, Lombard LL, Roaf ER, Drager LR, Calalang I, Philip JH. Comparison of vital capacity induction with sevoflurane to intravenous induction with propofol for adult ambulatory anesthesia. Anesth Analg 1999;89(3):623–7. 3. Ghatge S, Lee J, Smith I. Sevoflurane: an ideal agent for adult day-case anesthesia? Acta Anaesthesiol Scand 2003; 47(8):917–31. 4. van den Berg AA, Chitty DA, Jones RD, Sohel MS, Shahen A. Intravenous or inhaled induction of anesthesia in adults? An audit of preoperative patient preferences. Anesth Analg 2005;100(5):1422–4. 5. Hopkins PM. Nitrous oxide: a unique drug of continuing importance for anaesthesia. Best Pract Res Clin Anaesthesiol 2005;19(3):381–9. 6. Shakir AAK, Ramachandra V, Hasan MA. Day surgery postoperative nausea and vomiting at home related to peroperative fentanyl. J One-day Surg 1997;6(3):10–1. 7. Smith I. Avoidance of fentanyl reduces nausea and vomiting associated with volatile induction and maintenance of
8.
9.
10.
11.
12.
13.
14.
15.
16. 17.
18.
19.
anaesthesia with sevoflurane (abstract). Anaesthesia 2007; 62:309. Sukhani R, Vazquez J, Pappas AL, Frey K, Aasen M, Slogoff S. Recovery after propofol with and without intraoperative fentanyl in patients undergoing ambulatory gynecologic laparoscopy. Anesth Analg 1996;83(5):975–81. Cartwright DP, Kvalsvik O, Cassuto J, Jansen JP, Wall C, Remy B, et al. A randomized, blind comparison of remifentanil and alfentanil during anesthesia for outpatient surgery. Anesth Analg 1997;85(5):1014–9. Coloma M, Chiu JW, White PF, Armbruster SC. The use of esmolol as an alternative to remifentanil during desflurane anesthesia for fast-track outpatient gynecologic laparoscopic surgery. Anesth Analg 2001;92(2):352–7. Cheng CR, Sessler DI, Apfel CC. Does neostigmine administration produce a clinically important increase in postoperative nausea and vomiting? Anesth Analg 2005;101(5): 1349–55. Gupta A, Stierer T, Zuckerman R, Sakima N, Parker SD, Fleisher LA. Comparison of recovery profile after ambulatory anesthesia with propofol, isoflurane, sevoflurane and desflurane: a systematic review. Anesth Analg 2004;98(3): 632–41. Sneyd JR, Carr A, Byrom WD, Bilski AJ. A meta-analysis of nausea and vomiting following maintenance of anaesthesia with propofol or inhalational agents. Eur J Anaesthesiol 1998;15(4):433–45. Tramer M, Moore A, McQuay H. Meta-analytic comparison of prophylactic antiemetic efficacy for postoperative nausea and vomiting: propofol anaesthesia vs omitting nitrous oxide vs total i.v. anaesthesia with propofol. Br J Anaesth 1997; 78(3):256–9. Yogendran S, Asokumar B, Cheng DC, Chung F. A prospective randomized double-blinded study of the effect of intravenous fluid therapy on adverse outcomes on outpatient surgery. Anesth Analg 1995;80(4):682–6. Smith I. Cost considerations in the use of anaesthetic drugs. Pharmacoeconomics 2001;19(5 Pt 1):469–81. Song D, Joshi GP, White PF. Fast-track eligibility after ambulatory anesthesia: a comparison of desflurane, sevoflurane, and propofol. Anesth Analg 1998;86(2):267–73. Millar II. J. Fast-tracking in day surgery. Is your journey to the recovery room really necessary? Br J Anaesth 2004; 93(6):756–8. Joshi GP, Jamerson BD, Roizen MF, Fleisher L, Twersky RS, et al. Is there a learning curve associated with the use of remifentanil? Anesth Analg 2000;91(5):1049–55.