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On-line version ISSN 1806-907X
Rev. Bras. Anestesiol. vol.52 no.2 Campinas Mar./Apr. 2002
Thoracic epidural anesthesia with ropivacaine for plastic surgery*
Ropivacaína en bloqueo peridural torácico para cirugía plástica
José Roberto Nociti, TSA, M.D.I; Paulo Sérgio Mateus Serzedo, TSA, M.D.II; Eduardo Barbin Zuccolotto, TSA, M.D.II; Raul Gonzalez, M.D.III
IICo-responsável pelo CET/SBA
IIICirurgião Plástico, Chefe da Clínica Raul Gonzalez, Hospital Afiliado do CET/SBA
BACKGROUND AND OBJECTIVES:
Thoracic epidural blockade is a method of hypotensive anesthesia able to reduce
bleeding during surgery. This non-comparative study aimed at evaluating the
results of thoracic epidural blockade with 0.5% ropivacaine associated to propofol
continuous infusion sedation in plastic surgery.
METHODS: Participated in this study 60 female patients aged 18 to 62 years, physical status ASA I or II, scheduled for combined plastic surgeries of breast, abdomen, gluteus and liposuction. After epidural puncture in T9-T10 or T10-T11, patients received 40 ml of 0.5% ropivacaine and 15 µg sufentanil. Additional local anesthetic doses were administered through an epidural catheter, if necessary. Sedation was induced with 40 to 50 µg.kg-1.min-1 propofol continuous infusion. Blockade installation and regression, hemodynamic and respiratory parameters and the incidence of adverse effects were investigated.
RESULTS: Upper sensory block level was T2 in 52 patients (86.6%), C4 in 4 (6.6%), and T3 in 4 (6.6%). Mean onset time was 9.1 ± 8.2 min. Motor block grade 2 was obtained in 61.7% of patients, and grade 1 in 38.3%. Mean time for complete motor block regression was 377.9 ± 68.5 min. Mean time for first spontaneous pain complaint was 965.1 ± 371.3 min. SBP, DBP, MBP and HR mean values have significantly decreased as compared to control as from 15 min after local anesthetic injection, thus characterizing hypotensive anesthesia. Thirteen patients (21.7%) with SBP < 65 mmHg and/or MBP < 50 mmHg received a vasopressor (ethylphedrine) and 4 patients (6.7%) with HR < 50 bpm received atropine. No patient needed blood transfusion.
CONCLUSIONS: Thoracic epidural blockade with 0.5% ropivacaine and 15 µg sufentanil associated to propofol continuous infusion sedation is a satisfactory hypotensive anesthesia technique for combined plastic surgeries involving breast, abdomen, gluteus and liposuction. Continuous monitoring of hemodynamic and respiratory parameters as well as controlling blockade effects on those parameters are critical for the success and safety of the technique.
Key words: ANESTHETICS, Local: ropivacaíne; ANESTHETIC TECHNIQUES, Regional: thoracic epidural; SURGERY, Plastic
JUSTIFICATIVA Y OBJETIVOS:
El bloqueo peridural torácico constituye técnica de anestesia hipotensiva,
capaz de reducir el sangramiento en el campo operatorio. El presente estudio
no-comparativo tiene por finalidad observar los resultados del bloqueo peridural
torácico con ropivacaína a 0,5% asociado a sedación con infusión
continua de propofol en cirugía plástica.
MÉTODO: Participaron del estudio sesenta pacientes del sexo femenino con edades entre 18 y 62 años, estado físico ASA I ó II, sometidas a cirugías plásticas combinadas envolviendo mama, abdomen, glúteos, lipoaspiración. Después de punción peridural en T9-T10 óT10-T11, recibieron 40 ml de solución de ropivacaína a 0,5% y sufentanil 15 µg. Dosis subsecuentes de anestésico local fueron administradas a través de catéter cuando necesarias. La sedación fue obtenida con infusión venosa continua de propofol 40 a 50 µg.kg-1.min-1. Fueron evaluadas las características de instalación y regresión del bloqueo, la evolución de los parámetros hemodinámicos y respiratorios, la incidencia de eventos adversos.
RESULTADOS: El nivel superior de bloqueo sensorial fue T2 en 52 pacientes (86,6%), C4 en 4 (6,6%) e T3 en 4 (6,6%). La media para el tiempo de latencia fue 9,1 ± 8,2 minutos. Se obtuvo bloqueo motor grado 2 en 61,7% de las pacientes y grado 1 en 38,3%. La media para el tiempo de regresión completa del bloqueo motor fue 377,9 ± 68,5 minutos. La media para el tiempo de la primera queja espontanea de dolor fue 965,1 ± 371,3 minutos. Los valores medios de PAS, PAD, PAM y FC decrecieron significativamente en relación al control a partir de los 15 min después de la inyección de anestésico local, caracterizando anestesia hipotensiva. Trece pacientes (21,7%) que presentaron PAS < 65 mmHg y/o PAM < 50 mmHg recibieron vasopresor (etilfedrina) y 4 (6,7%) que presentaron FC < 50 bpm recibieron atropina. No fue necesaria transfusión sanguínea en ningún paciente.
CONCLUSIONES: El bloqueo peridural torácico con ropivacaína a 0,5% y sufentanil 15 µg, asociado a la sedación con propofol en infusión continua, constituye método de anestesia hipotensiva de buena calidad para cirugías plásticas combinadas envolviendo mama, abdomen, glúteos y lipoaspiración. La monitorización contínua de los parámetros hemodinámicos y respiratorios y el control de los efectos del bloqueo sobre estos parámetros son indispensables para el suceso y la seguridad de la técnica.
Plastic surgery is one of the surgical specialties which benefits most from induced hypotension. For a long time it has been observed that maintaining systolic blood pressure not higher than 65 mmHg and mean blood pressure not higher than 50 mmHg is safe and significantly decreases surgical bleeding 1,2. This observation has evolved to the concept of hypotensive anesthesia3 meaning anesthetic techniques aiming at safely decreasing bleeding. One of these techniques is the epidural block, thanks to preload and systemic vascular resistance decrease and, in the case of thoracic epidural block, also a decrease in myocardial contractility secondary to the blockade of sympathetic fibers to the heart 4,5.
On the other hand, good results have been obtained with ropivacaine, a new local anesthetic (LA) drug of the pipecholxylidide group, in epidural anesthesia 6, with emphasis to less motor block 7 and lower cardiovascular and nervous system toxicity, as compared to bupivacaine 8.
This non-comparative study aimed at evaluating the results of thoracic epidural block with 0.5% ropivacaine associated to sufentanil and propofol continuous infusion sedation in plastic surgery.
After the Hospitals Ethics Committee approval, participated in this study 60 patients according to the following selection criteria:
1. Female gender, aged 18 years
2. Physical status ASA I or II;
3. Scheduled for combined elective plastic surgeries of the breast, abdomen, gluteus and liposuction.
Patients were premedicated with oral flunitrazepam (30 mg) 60 minutes before surgery.
After a large vein catheterization and starting a 5% glucose solution infusion, epidural space puncture was performed in T9-T10 or T10-T11 with patients in the sitting position. Epidural space was identified through the loss of resistance to air technique and 40 ml of 0.5% ropivacaine (corresponding to 200 mg of LA) associated to 15 µg sufentanil was administered at the speed of 5 ml.min-1. Next, a catheter was introduced in the epidural space 8 to 10 cm in the cephalad direction for the administration of additional ropivacaine doses (15 ml of 0.5% solution corresponding to 75 mg), whenever required by surgery duration.
After epidural block, sedation was induced with intravenous midazolam (0.10 mg.kg-1) followed by propofol continuous infusion at the speed of 40 to 50 µg.kg-1.min-1 throughout the procedure. An oxygen flow of 1 - 2 L.min-1 was routinely administered through a catheter introduced in an oropharyngeal cannula (Guedel).
The following parameters were non-invasively monitored: systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), heart rate (HR), ECG, respiratory rate (RR) and pulse oximetry (SpO2). Values were recorded in the following moments:
Before epidural block (control);
· 5 minutes after LA injection;
· 15 minutes after injection;
· 30 minutes after injection;
· At every 30 minutes from then on.
Intraoperative fluids were administered according to the rule proposed by Jenkins and Giesecke 9, for larger superficial surgeries: 8 to 10 ml.kg-1.h-1, starting with 5% glucose solution until the volume of 500 ml and continuing with lactated Ringers solution and 5% glucose, never exceeding the total dose of 125 g glucose. For wet liposuction, the surgeon has infiltrated the areas to be sucked with saline containing 0.1% lidocaine and epinephrine 1:1.000.000 10. Since more than 80% of the infiltrated volume ends up absorbed by circulation 11,12, this volume was subtracted from the volume calculated by Jenkins and Gieseckes rule and lower than expected final fluid volume was administered.
Sensory block was evaluated as follows:
a) Onset time - time elapsed between
end of injection and absence of pain at stimulation with a surgical clamp in
the sensory area corresponding to the puncture level;
b) Upper block - by skin stimulation with a surgical clamp at 2-minute intervals, considering the upper level the one abtained repeatedly in 3 consecutive stimulations.
Motor block intensity was evaluated by Bromages method 13.
During post-anesthetic recovery, the following parameters were studied and recorded:
a) Time for first spontaneous pain
complaint - elapsed between LA injection and the moment patients referred their
first spontaneous pain complaint at the operated site, needing systemic analgesia;
b) Time for total motor block regression - elapsed between LA injection and motor block zero according to Bromages scale.
The incidence of the following adverse effects was observed and recorded: SBP < 65 mmHg and/or MBP < 50 mmHg; bradycardia; arterial blood desaturation; pain at LA injection; shivering; nausea and vomiting; pruritus. Whenever SBP fell below 65 mmHg and/or MBP fell below 50 mmHg, an intravenous vasopressor (ethylphedrine) was administered. Bradycardia was considered as HR decrease to 50 bpm or below and was treated with intravenous atropine.
Arterial blood desaturation was defined as SpO2 £ 85% for 30 seconds or more. Shivering was treated with 20 to 30 mg intravenous meperidine; nausea and vomiting with 8 mg intravenous ondansetron. First spontaneous pain complaint after surgery was treated with 75 mg muscular dichlophenac.
Mean hemodynamic parameters were compared by analysis of variance for serial measurements (ANOVA), considering significant a p < 0.005.
Demographics are shown in table I. Eleven patients (18.3%) were in chronic use of one or more of the following drugs: levotiroxine, paroxetine, hydrochlorothiazide, furosemide, bromazepam, enalapril, chloroquine, omeprazol, lamivudine, nevirapine.
Patients distribution per surgery type is shown in table II. Liposuction was performed in several combined body regions: chest, abdomen, hips and thighs. Surgeries were performed with patients in the horizontal position with maximum dorsal elevation of 30º.
Mean procedure duration was 277.9 ± 55.3 min (extremes of 150 and 390 min). Epidural space puncture level was T9-T10 in 50 patients (83.3%) and T10-T11 in 17 patients (28.3%).
Mean onset time was 9.1 ± 8.2 min (extremes of 6 and 12 min). Upper sensory block level was T2 in 52 patients (86.6%), C4 in 4 (6.6%) and T3 in 4 (6.6%). Caudal sensory block has reached sacral dermatomes allowing for procedures in the gluteal region.
Motor block levels and patient percentages are shown in figure 1.
Mean time for first spontaneous pain complaint was 965.1 ± 371.3 min (extremes of 510 and 1440 min). Mean total motor block regression time was 377.9 ± 68.5 min (extremes of 300 and 600 min).
SBP, DBP and MBP mean values in seven observation moments are shown in figure 2 and mean HR is shown in figure 3. Means have significantly decreased after 15 minutes for both groups as compared to control.
Adverse events are shown in table III. There has been no need for perioperative blood or by-products administration.
Blockade was adequate for all patients with no need for additional analgesia.
Results have shown that extensive epidural thoracic and lumbar blockade with 0.5% ropivacaine associated to propofol continuous infusion sedation is a good and safe anesthetic technique for combined plastic surgeries involving different body regions.
The addition of an opioid (sufentanil in this case) to LA seems to play an important role in the quality of the blockade and in postoperative analgesia, which is in line with other authors 14. Moreover, small opioid doses in the thoracic epidural space seem to contribute to sedation 15,16, thus decreasing the need for propofol.
Thoracic epidural block has well known effects on the cardiovascular system, resulting in a selective sympathetic heart enervation blockade (T1-T5) 17. These are beneficial effects because they decrease cardiovascular excitation and reduce myocardial oxygen consumption by controlling systolic blood pressure and heart rate. There are multiple clinical implications, such as decrease in cardiovascular excitatory responses to tracheal intubation 18, perioperative myocardial ischemia control in cardiac diseases 19 and, in our case, less bleeding in plastic surgeries with hypotensive anesthesia.
Tachycardia is a major factor for increasing cardiac output and bleeding during surgery. The technique has adequately controlled such factor, as shown in figure 3. It is worth mentioning that systemic LA absorption after epidural administration may result in direct myocardial depression and bradycardia, configuring the cardiotoxic potential of such drugs. This is especially important with bupivacaine and seems to be responsible for circulatory failures reported with this LA, especially in obstetrics 20,21. Ropivacaine is significantly less cardiotoxic than bupivacaine 22,23, thus decreasing the chances for circulatory failure caused by the addition of effects with sympathetic block. However, there were 4 bradycardia episodes (6.6% of cases) with HR decreases to 50 bpm or less, promptly reverted with atropine.
Areas to be sucked during liposuction are infiltrated by the surgeon with large volumes of saline with highly diluted lidocaine and epinephrine (tumescent solution). Low concentration and decreased tissue perfusion change lidocaines clinical pharmacology in the tumescent solution, increasing the highest LA dose in up to 7 to 8 times the recommended dose for traditional infiltration 24. Indeed, there has been no toxicity by systemic LA absorption in our study. Regardless of the extremely low concentration, lidocaine may contribute to a certain degree of analgesia in the infiltrated areas.
After blockade, there has been a decrease in blood pressure, as shown in figure 2. It is important to highlight that this was a desired effect of hypotensive anesthesia aiming at decreasing surgical bleeding. SBP was maintained in values not below 65 mmHg and MBP in values not below 50 mmHg, which are considered safe from brain and myocardial perfusion viewpoint 1,2. SBP and MBP decreases below desirable values were observed in 13 patients (21.7%) and were easily and promptly treated with ethylphedrine. This is a mixed action vasopressor of the ephedrine group 25, constituting a good choice to revert hypotension caused by sympathetic blockade during regional anesthesia, with the additional advantage of not causing the same HR increase following the administration of ephedrine.
The incidence of pharmacologically treated hypotension and bradycardia in our study was lower than what has been reported by other authors using lidocaine or bupivacaine in thoracic epidural blocks 26,27.
It is important to remind that, even during high epidural blocks, there are compensating mechanisms which allow for some sympathetic activity. Indeed, studies have shown that epidural anesthesia with upper blockade level in C8 is not followed by significant epinephrine plasma level decrease 28; the maintenance of such levels should compensate, at least partially, circulatory depressing effects of epidural anesthesia.
The association of epidural block with propofol continuous infusion sedation in the doses used in this study has provided more comfort to patients and did not result in circulatory parameters deterioration, which is in line with previous observations 29,31.
Similarly, there has been no arterial blood oxygen desaturation to SpO2 £ 85% throughout the procedure, except for one patient. It is known that thoracic epidural block with concentrated bupivacaine solutions causes a moderate decrease in vital capacity and maximum inspiratory flow, probably due to a certain degree of intercostal muscles relaxation 32. However, less concentrated solutions of an LA such as ropivacaine, which induces a less intense motor block as compared to bupivacaine, may decrease the chances of significant involvement of respiratory muscles. On the other hand, it has already been reported that sedation with propofol infusion at the speed used in our study is safe for the respiratory system 31.
Time elapsed between LA and sufentanil injection to the first systemic analgesic need was considerable and may have been influenced by the preemptive analgesia provided by sufentanil; this effect has already been observed for other epidural opioids, especially for breast and limbs surgery 33.
Postoperative shivering was seen in 8 patients (13.3%), all submitted to liposuction, and was probably caused by the decrease in body temperature, secondary to heat loss to the environment facilitated by epidural vasodilation, and to body cooling by infiltrating sucked areas with cold saline. Shiverings was treated with meperidine, which produces significant decrease in body temperature threshold and is able to trigger the thermoregulating mechanism 34.
The conclusion was that thoracic epidural block with 0.5% ropivacaine plus sufentanil, associated to propofol continuous infusion sedation is a safe and good hypotensive anesthesia method for combined plastic surgeries involving breast, abdomen, gluteus and liposuction. It is not a simple procedure; its success depends on anesthesiologists skills, on their ability to deal with blockade effects on circulatory and respiratory parameters, on the constant monitoring of such parameters and on the synchronism of the surgical team. The concomitance of all those factors is paramount for assuring good results and patient safety.
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Dr. José Roberto Nociti
Rua Stélio Machado Loureiro 21 - Alto da Boa Vista
14025-470 Ribeirão Preto, SP
Submitted for publication July 17, 2001
Accepted for publication October 09, 2001