Henry Medina,^* Alejandro Londoño,^*** Iván Fernando Quintero^***

* Anestesiólogo. Clinica Rostrum y Corpus, Cali. Docente del Departamento de Anestesiología. Universidad del Valle. Miembro del grupo de investigación en Anestesiología y Reanimación. Univalle. Email: hmedina20@gmail.com
** Anestesiólogo. Universidad del Valle.
*** Residente de Anestesiología. Universidad del Valle. Miembro del grupo de investigación en Anestesiología y Reanimación. Univalle.

Recibido: septiembre 17/2009 - Aceptado: noviembre 11/2009

Two or more differently associated surgical procedures are often performed on the same patient during plastic surgery (i.e. liposculpture, lipectomy or mammoplasty) and even other types of aesthetic and non-aesthetic surgery. The anaesthetic techniques usually used is general anaesthesia, having the advantage of including the use of current drugs such as remiphentanyl, sevoflurane or desflurane allowing rapid awakening and rapid change in anaesthetic depth. However, it presents the inconvenience of immediate postoperative pain, above all, procedures including retropectoral mammaplasty and lipectomy with abdominal muscle tucking. The other regularly used technique is epidural anaesthesia with sedation which provides multiple advantages such as reducing the risk of deep venous thrombosis, less bleeding and suitable analgesia during immediate postoperative period. However, its adverse effect means that a patient becomes very tired and uncomfortable following 1.5-2 hours of surgery, requiring slight or even deep sedation. Furthermore, anaesthesia must often be given at the same time for dermatomas as high as C6 and as low as sacro ones (Figure 1) requiring extensive epidural block. A good alternative is thus to use a combined epidural-light general anaesthesia, trying to take advantage of the benefits of both techniques and reduce the inconveniences inherent in each of them.

Combined anaesthesia (epidural-general) has been used for many decades now around the world in major abdominal and thorax surgery, these usually being prolonged surgeries involving a lot of postoperative pain. The advantages of using the combined technique include: lower consumption of general anaesthetics (halogenated and endovenous) as well as muscle relaxers (2,3,4). Local anaesthetics may also be used at low concentrations, such as 0.0625-0.125% bupivacaine (5,6,7). The reduced awakening time should also be highlighted (7). Previous studies have shown reduced blood loss (9,10) from arrythmias and catecholamine-releasing agents (11). It is associated with shorter extubation times in thorax surgery and intensive care units (ICU) stay (12). It also improves lower limbs´ haemodynamic, increasing poplitial venous blood flow speed and volume, thereby reducing the risk of venous thrombosis (13).

The main secondary effect associated with the combined technique is hypotension depending on both techniques´ dose (5,6,14), bradycardia and respiratory alteration with the epidural technique and the risk of light general anaesthesia-related intraoperative awakening.

Technique

After informed consent had been obtained, an epidural catheter was placed in T10-11 in all patients; if difficulty was presented (technically) then it was placed in a higher or lower space. An epidural catheter test was carried out with 3 ml 0.75% levobupivacaine with epinephrine (1:200,000) for discarding intravascular or subarachnoideal presence. 15-20 ml of the same drug at 0.175%-0.25% with or without 75 to 100 ug phentanyl was administered 3 minutes after the test proved negative (epidural phentanyl was only administered to those patients who asked for epidural analgesia during the following two postoperative days). General anaesthesia was induced after 5-10 minutes with 4-5 mg midazolam, 1-1.5 mcg/ Kg remiphentanyl in 3 min, 1-1.5 mg/Kg propofol and 50-75 mcg/Kg cisatracurium, followed by intubation.

Once the peridural catheter had been placed and general anaesthesia induced, patients were (non-randomly) distributed into two groups according to the general anaesthesia maintenance scheme.

General anaesthesia was maintained in a group of patients with isoflurane in the gas analyser at MAC sedation and remiphentanyl graduated according to hemodynamic response and painful stimulus, bearing in mind that the epidural level reached was T2-4. The need for increasing the remiphentanyl infusion rate in mammaplasty (mainly in high liposculpture) should be noted as painful stimulus could reach C7-8 (figure 1).

The other group of patients was maintained with propofol-remiphentanyl; propofol was administered between 3.5-5 mg/Kg/hour; however, 30 to 50 mg was added when a patient required a change of position or surface and remiphentanyl was usually infused at 0.1-0.15 mcg/Kg/min. When required, the infusion rate was increased to 0.2 mcg/Kg/min for short periods.

1 to 2 mg ethylephrine was administered every 7 to 10 minutes to those patients who presented a 30% reduction in mean arterial pressure or an absolute value of less than 60 mmHg during the intraoperative period. Atropine was adminis tered when cardiac frequency was less than 50 beats per minute.

A booster dose was administered 2 to 3 hours after the first dose, having 30%-50% initial volume (7-10 ml levobupivacaine, 0.15-0.25%). If a patient asked for postoperative epidural analgesia, this was also initiated during the intraoperative period 2-3 hours after the initial dose, at a concentration of 0.125% levobupivacaine plus 1-1,5 mcg/ml phentanyl, at 4-5 ml/hour infusion rate. The literature recommends administering 30%-50% of the initial dose at an interval of 2/3 the expected time for the block to last or when it was calculated that the block had regressed 2 segments, without forgetting that there is great inter-individual variability of up to 5 dermatomas when using the same epidural technique and volume (15).

All patients were asked about their memories of intraoperative awakening, once they had become orientated during recovery time.

Data analysis

Statistical SPSS 16.0 software was used for processing the data. Descriptive statistics were used for analysing them. Numerical variables were expressed in terms of means and percentiles. Standard deviation and range were used for measuring dispersion.

The 67 patients described were aged 19 to 60, average age being 35 ± 10.15 years; 95.5% were female. 117 surgical procedures were performed, liposuction (51.3%), mammoplasty (19.7%) and lipectomy (14.5%) being the most frequent, having an average time for surgery of 185min ± 73 and 239 min ± 80 for anaesthesia. All patients had an epidural catheter, the most used position being T10-T11 (60.6%) followed by T11-T12 (34.8%).

The epidural boost dose was placed on average at 136 min ± 60 min with 0.125% (56%), 0.15% (27.3%), 0.175% (9.1%) levobupivacaine with 7cc ± 2.4 average volume.

The booster was administered to 58% of the patients by continuous infusion of 0.125% levobupivacaine and 1-1.5 mcg/ml phentanyl; postoperative epidural analgesia was left for 72 hours.(Table 1)

Associated with neuroaxial block, 40 patients (59.1%) had general anaesthesia with isoflurane plus remiphentanyl. The vaporiser dial was set at 1.19 ± 0.2%, with fresh gas flow of less than 1 litre/min (for obtaining a 0.5-0.6 MAC concentration in the gas analyser) and 0.11mcg/kg/min ±0.03 average remiphentanyl infusion.

Anaesthesia with propofol and remiphentanyl, associated with neuroaxial block, was supplied to 27 (40.9%) of the remaining patients; average remiphentanyl infusion was 0.14 mcg/kg/min ±0.04 and that of propofol was 4.43 mg/Kg/hour ±0.5.

63.6% of the patients required some management with ethylephrine during anaesthesia; average dose was 5.7mg. This pharmacological requirement was presented at any time during the surgery without having a specific lapse of time. No episodes of bradycardia were presented which required management with atropine. (Table 2).

None of the patients reported having memories of the surgery. One patient presented an episode of occular aperture which was managed by increasing anaesthetic depth. Four patients (6.1%) from the group to which continuous peridural analgesia was not administered presented acute postoperative pain which was managed with epidural boost and/or systemic opioids. No complications inherent in the anaesthetic technique were presented.

The description of this anaesthetic technique represents an exploration into the joint use of low-dose general anaesthesia and epidural anaesthesia in aesthetic surgery. This joint technique has been described in the scientific literature as being combined light anaesthesia and has been used with satisfactory results in prolonged and painful procedures such as thorax surgery and major abdominal surgery, providing benefits accompanied by a suitable safety profile. It should be noted that using these two techniques could lead to intensifying adverse effects; however, it has been shown that their use at a low dose has no negative impact on their use, meaning that combined light anaesthesia is described in this anestearticle as being an attractive in aesthetic surgery.

Locating the peridural catheter in T10-11 was the most frequently used position, allowing analgesia to be provided at metamers as high as C-7 and as low as S-2. Using this technique also provides intraoperative analgesia and helps control pain during the postoperative period (2), ostensibly reducing general anaesthetic requirements (3,4,5).

The local anaesthetic concentrations used were low and the volume used was 15 ml on average. Using such local anaesthetic doses have been seen to be effective in controlling intra- and postoperative pain, they also allowed reducing the general anaesthetic requirement, motor block or alterations in micturition during the immediate postsurgical period (5,6,16,17) and the time spent in recovery units. It should be stated that some surgical procedures require managing metamers found outside the analgesic block; such situation was satisfactorily overcome by modifying the remiphentanyl infusion rate.

Hypotension is an adverse effect which is frequently presented during combined Anaesthesia, even at a low dose, which is easily treated with vasoactive agents such as ephedrine (6,14,19,20). Ethylephrine was used in the present study for managing hypotension as it is a vasoactive agent having a pharmacological profile similar to that of ephedrine. Average dose for this agent was 5.7 mg, allowing this complication to be satisfactorily managed without complications. It should be stressed that ethylephrine is being used more frequently in patients to whom combined anaesthesia has been applied with isoflurane-remiphentanyl rather than propofol-remiphentanyl, no evident explanation having emerged for this situation.

Intraoperative awakening and remembering are events having a greater risk of being presented during combined anaesthesia than with general anaesthesia used as sole technique; this situation may be explained by low endovenous and inhalatory anaesthetic requirements (2,3,4,6,18). The present study has been limited by a lack of BIS measurement; however, it should be stres sed that a case of intraoperative awakening was presented which did not represent a memory of the situation, such event being satisfactorily managed with greater depth anaesthetic. It also lacked cases of intraoperative remembering.

Aesthetic plastic surgery (mainly the combination of procedures such as liposculpture, abdominoplasty and retropectoral mammaplasty) implies intraoperative pain, such as severe intensity postoperative pain and dermatomas in many cases, meaning that peridural analgesia is a very good alternative.

Peridural anaesthesia and analgesia provide benefits such as reducing the risk of thrombosis of the lower limbs and intraoperative bleeding (9,10,13,23,24), a situation favouring the use of this technique in aesthetic surgery, mainly in liposculpture and abdominaplasty where these events are frequent and feared complications.

Low peridural anaesthetic concentrations reduced the frequency of lower limb motor block, leading to patients´ shorter stay in recovery, a situation which is also favoured by rapid awakening associated with administering low dose general anaesthesia (7,11,12).

According to the present article´s findings, it may be established that general-epidural anaesthesia constitutes an attractive alternative for performing aesthetic surgery. The findings in the present study, the data and conclusions obtained should be suitably supported by experimental designs.

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Conflicto de intereses: ninguno declarado.