Topical anesthesia associated with sedation for phacoemulsification: experience with 312 patients

Abstracts

JUSTIFICATIVA E OBJETIVOS: A anestesia tópica vem ganhando espaço nas operações de catarata, sobretudo após os avanços advindos com a técnica de facoemulsificação. O objetivo desse estudo foi avaliar a eficácia da anestesia tópica associada à sedação para operações de catarata por facoemulsificação. MÉTODO: Estudo prospectivo de 312 pacientes, ASA I e II, com idades entre 41 e 89 anos. Foi realizada a facoemulsificação sob anestesia tópica (cinco minutos antes da operação, por gotejamento com proximetacaína a 0,5%) associada à sedação (midazolam, 1 mg, por via venosa, administrado 15 minutos antes da operação). Alfentanil em bolus de 125 µg por via venosa foi administrado sob demanda. Variáveis como dor no intra-operatório, consumo de alfentanil, efeitos colaterais, tempo de recupe\ração e nível de satisfação do paciente foram analisados. RESULTADOS: No período intra-operatório foram observados oito (2,6%) casos de bradicardia, quatro (1,3%) de edema epitelial, dois (0,65%) de náuseas e duas (0,65%) rupturas de cápsula posterior. No pós-operatório foram observados 15 (4,8%) casos de náuseas, seis (1,9%) casos de tonturas, dois (0,65%) casos de vômitos e um (0,32%) caso de bradicardia. O tempo médio de recuperação pós-operatória foi de 21,77 minutos. O consumo de alfentanil variou entre 125 µg e 1.250 µg, com um consumo médio de 537 µg. Trezentos (96,2%) pacientes classificaram a técnica anestésica como boa e 12 (3,8%) pacientes classificaram como regular. Quarenta e dois pacientes relataram dor em algum momento da operação e quatro (1,3%) pacientes disseram que caso necessitassem realizar um novo procedimento de facoemulsificação não gostariam de ser submetidos à mesma técnica anestésica. CONCLUSÕES: A anestesia tópica com sedação em pacientes submetidos a operações de catarata por facoemulsificação, neste estudo, demonstrou eficácia, fácil aplicação e complicações mínimas.

ANESTESIA, Local; CIRURGIA, Oftálmica; CIRURGIA, Oftálmica; SEDAÇÃO

SCIENTIFIC ARTICLE

Topical anesthesia associated with sedation for phacoemulsification. Experience with 312 patients^*

Tópica asociada a la sedación para facoemulsificación. Experiencia con 312 pacientes

Romero Henrique Carvalho Bertrand^I; João Batista Santos Garcia, TSA^II; Caio Márcio Barros de Oliveira, TSA^III; Adriana Leite Xavier Bertrand^IV

^IProfessor Assistente da Disciplina de Oftalmologia da UFMA

^IIProfessor Adjunto Doutor da Disciplina de Anestesiologia da UFMA; Especialista em Dor, Responsável pelo Ambulatório de Dor do Hospital Universitário da UFMA

^IIIAnestesiologista; Mestre em Medicina pela Universidade Federal de São Paulo

^IVOftalmologista Assistente do Hospital de Olhos de São Luís

^{Correspondence to}

SUMMARY

BACKGROUND AND OBJECTIVES: The use of topical anesthesia in cataract surgeries has been increasing, especially after the development of phacoemulsification. The objective of this study was to evaluate the efficacy of topical anesthesia associated with sedation for cataract extraction by phacoemulsification.

METHODS: A prospective study was conducted with 312 patients, ASA I and II, ages 41 to 89 years. Phacoemulsification was performed under topical anesthesia (5 minutes before surgery, by dripping 0.5% proximetacaine) associated with sedation (intravenous midazolam, 1 mg, administered 15 minutes before the surgery). Intravenous bolus of alfentanil, 125 µg, were administered under demand. Parameters, such as intraoperative pain, consumption of alfentanil, side effects, recovery time, and level of patient satisfaction were analyzed.

RESULTS: In the intraoperative period, 8 (2.6%) cases of bradycardia, 4 (1.3%) of epithelial edema, 2 (0.65%) of nausea, and 2 (0.65%) ruptures of the posterior capsule were observed. In the postoperative period, 15 (4.8%) cases of nausea, 6 (1.9%) cases of dizziness, 2 (0.65%) of vomiting, and 1 (0.32%) case of bradycardia were observed. The mean time of postoperative recovery was 21.77 minutes. Consumption of alfentanil varied from 125 µg to 1250 µg, with a mean consumption of 537 µg. Tree hundred (96.2%) patients classified the technique as good and 12 (3.8%), as regular. Forty-two patients complained of pain sometime during surgery, and 4 (1.3%) patients said that if they needed another phacoemulsification, they would not like to undergo the same anesthetic technique.

CONCLUSIONS: In this study, topical anesthesia with sedation of patients undergoing cataract removal by phacoemulsification demonstrated to be effective, easy to apply, and had a very low incidence of complications.

Key Words: ANESTHESIA, Local; topic; SEDATION: intravenous; SURGERY, Ophthalmologic: cataract, phacoemulsification.

RESUMEN

JUSTIFICATIVA Y OBJETIVOS: La anestesia tópica ha venido obteniendo espacio en las operaciones de catarata, principalmente después de los avances provenientes de la técnica de facoemulsificación. El objetivo de este estudio fue evaluar la eficacia de la anestesia tópica asociada a la sedación para operaciones de catarata por facoemulsificación.

MÉTODO: Estudio prospectivo de 312 pacientes, ASA I y II, con edades entre 41 y 89 años. Fue realizada la facoemulsificación bajo anestesia tópica (5 minutos antes de la operación, por goteo con proximetacaína a 0,5%) asociada a la sedación (midazolan, 1 mg, por vía venosa, administrado 15 minutos antes de la operación). Alfentanil en bolus de 125 µg por vía venosa fue administrado bajo demanda. Variables como el dolor en el intraoperatorio, consumo de alfentanil, efectos colaterales, tiempo de recuperación y nivel de satisfacción del paciente se analizaron.

RESULTADOS: En el período intraoperatorio se observaron 8 (2,6%) casos de bradicardia, 4 (1,3%) de edema epitelial, 2 (0,65%) de náuseas y 2 (0,65%) rupturas de cápsula posterior. En el postoperatorio se observaron 15 (4,8%) casos de náuseas, 6 (1,9%) casos de mareos, 2 (0,65%) casos de vómitos y 1 (0,32%) caso de bradicardia. El tiempo promedio de recuperación post-operatoria fue de 21,77 minutos. El consumo de alfentanil varió entre 125 µg y 1.250 µg, con un consumo promedio de 537 µg. Trescientos (96,2%) pacientes clasificaron la técnica anestésica como buena y 12 (3,8%) pacientes la clasificaron como regular. Cuarenta y de los pacientes relataron dolor en algún momento de la operación y 4 (1,3%) pacientes dijeron que si necesitasen realizar un nuevo procedimiento de facoemulsificación no les gustarían ser sometidos a la misma técnica anestésica.

CONCLUSIONES: La anestesia tópica con sedación en pacientes sometidos a operaciones de catarata por facoemulsificación, en este estudio, demostró eficacia, una fácil aplicación y complicaciones mínimas.

INTRODUCTION

Recent developments in the technology of cataract surgery, such as the introduction of phacoemulsification with minimal conjunctival, episcleral and muscular manipulation, reduction of the size of the surgical incision as well as its self-sealing profile, besides the use of foldable intraocular lenses, reduced the need of ocular akinesia and patient immobilization. Those changes also lead to changes in anesthetic techniques, which has always been aimed at safety and reduction in the incidence of complications secondary, mainly, to the introduction of the needle in the ocular cavity and systemic changes secondary to the injection of anesthetic agents, especially in elderly patients with associated diseases, which is the profile of most cataract patients ¹.

The world fasciectomy scenario concurred for the development of topical anesthesia in detriment of other techniques, such as retrobulbar, peribulbar, subtenonian, and subconjunctival blocks.

The use of topical anesthesia in eye surgery dates back to the XIX Century, when an aqueous solution of 5% cocaine was used for cataract removal; however, it was not widely accepted due to the toxic effects of the drug ^2,3. It was only in 1991 that 0.5% tetracaine eye drops were used ⁴. In 1993, topic 0.5% propacaine was used instead of tetracaine for the same purposes⁵. Nowadays, topical anesthesia can be achieved using anesthetics as drops, gel, or associated or not with intracameral anesthetics or sedation ⁴.

The objective of this study was to evaluate the efficacy, applicability and complications of topical anesthesia associated with sedation for cataract surgery by phacoemulsification.

METHODS

After approval by the Ethics Commission on Research of the Hospital Universitário Unidade Presidente Dutra da Universidade Federal do Maranhão and by the Clinical Board of the Hospital dos Olhos de Maranhão, a prospective study was conducted with 312 patients undergoing cataract phacoemulsification at the Hospital dos Olhos de São Luiz, Maranhão, Brazil, from April 2003 to April 2005.

Patients with contraindications for phacoemulsification, physical status ASA III and IV, glaucomatosis, history of eye surgery and patients with contraindications to the use of dypirone, midazolam, proximetacaine and alfentanil, such as hypersensitivity, were excluded fro the study.

All patients were operated by the same surgical team, composed of two surgeons, who used the same surgical technique and underwent the same anesthetic technique.

Patients were monitored routinely with non-invasive blood pressure, electrocardioscope and pulse oximetry. Initially, 1 liter of oxygen per minute was administered via a nasal catheter and intravenous midazolam 1 mg was administered 15 minutes before the surgery.

Topical ocular anesthesia consisted of the administration of 0.5% proximetacaine (4 or 5 drops) five minutes before the surgery and an intravenous bolus of alfentanil, 125 µg, was administered before the surgical incision and additional boluses were titrated as needed (when the patient complained of some type of discomfort or pain).

At the end of the surgery 1 g of intravenous dypirone was administered for postoperative analgesia and patients were transferred to the recovery room.

Patients remained under observation in the recovery room and were discharged when they met the following criteria: normal ambulation, were able to leave with their companion, absence of vomiting, were pain-free, oriented in time and space, had adequate levels of peripheral oxygen saturation and blood pressure was normal or did not show a fall greater than 20% of preoperative levels.

Duration of surgery and post-anesthetic recovery in minutes were analyzed according to the criteria mentioned before.

The presence of intra and postoperative intercurrences, such as bradycardia (heart rate < 50 bpm, treated with 0.5 mg of atropine), nausea and vomiting (treated with intravenous metoclopramide, 10 mg), respiratory depression (oxygen saturation < 90%, treated according to each case), epithelial edema (which remained under observation, without the need of a specific treatment) were recorded. Intraoperative pain was recorded as a spontaneous complaint or as a response to direct patient questioning. Due to the sedation used in the procedure, pain scales were not used to evaluate pain severity.

The total amount of alfentanil required by each patient was also recorded.

The need to change to other anesthetic or surgical technique was evaluated.

The following day, the surgeon asked patients whether if they would choose the same anesthetic technique if they needed another surgery and were instructed to respond yes or no. The degree of patient satisfaction with the anesthetic technique was evaluated, being classified as good, regular, or bad.

Measurements of central tendency (means) and dispersion (standard-deviation) were used for the statistical analysis of the data. The Chi-square test was used to compare the consumption of alfentanil per gender. The level of significance was determined as a p < 0.05.

RESULTS

Table I show the demographic data (gender, age, weight, height and body mass index) of all 312 patients.

Patients were distributed according to the ASA classification as follows: 122 patients were ASA I and 190 ASA II.

Ninety (28.8%) patients did not have associated diseases. Among the comorbidities, we observed that 174 patients (55.7%) were hypertensive, 21 (6.7%) diabetics, 21 (6.7%) had coronary insufficiency, six (1.9%) had cardiac arrhythmias, three (0.9%) had congestive heart failure, one (0.3%) had chronic renal failure, one (0.3%) had chronic obstructive pulmonary disease, one (0.3%) had asthma and one (0.3%) had hypothyroidism.

The surgery lasted 22.7 ± 5.7 minutes and post-anesthetic recovery occurred in 21.8 ± 5.4 minutes, according to the criteria specified.

Bradycardia was the most common intraoperative intercurrence affecting eight (2.6%) patients, followed by epithelial edema in four patients (1.3%), two patients (0.65%) complained of nausea and two (0.65%) had rupture of the posterior capsule, which did not cause any changes in the scheduled surgery. Hypotension, respiratory depression and vomiting were not observed (Table II).

Two hundred and seventy (86.5%) patients did not experience pain. Forty-two patients (13.5%) complained of pain during the surgery, 28 (9%) females and 14 (4.5%) males, but this difference was not statistically significant (Chi-square test, p = 0.8862).

The consumption of alfentanil varied from 125 µg to 1250 µg, with a mean of 537 ± 191 µg. Table IV shows patient distribution according to alfentanil consumption.

It was observed a greater percentage of female patients who required for doses of alfentanil above and below the mean consumption, without statistically significant differences between genders (Table V).

The surgical technique or the type of anesthesia did not have to be changed in any case. When asked by the surgeon on the following day, 306 (98%) patients said they would use the same type of anesthesia if they needed another surgery by phacoemulsification and only six (1.9%) patients said they would prefer another type of anesthesia.

As for the degree of patient satisfaction, 300 (96.2%) patients classified the anesthesia as good and 12 (3.8%) as regular; there were no patients who considered it a bad technique (Figure 1).

DISCUSSION

With the advent of phacoemulsification, topical anesthesia has been establishing itself as a minimally invasive technique ^5-9, increasing its popularity and drawing the interest of an increasing number of surgeons.

In the present study, 312 patients of both genders, physical status ASA I and II, were evaluated. There was a predominance of female patients in the study population; however, several authors have already reported that there are no statistically significant difference in the incidence of cataracts according to gender ^10,11.

The frequency of surgical treatment of cataracts in elderly patients who may have preexisting conditions is increasing. In this study, most patients were hypertensive (55.7%) but, although hypertension is one of the most frequent causes of cancellation of surgeries, there is no evidence in the medical literature that it is directly related with the development of cataracts ¹².

In the present study, 21 patients (6.7%) were diabetics. Diabetes mellitus is the most frequent and prevalent endocrinopathy in patients with cataracts. The surgery can be performed under topical anesthesia and sedation with satisfactory results and acceptable risks and it has a good possibility of being successful, although the success rate is smaller than in non-diabetic patients ¹³.

When evaluating 46 patients undergoing phacoemulsification under topical anesthesia with proximetacaine without sedation, several authors observed that surgeons on the learning curve and experienced surgeons accepted well the technique with greater discomfort for less experienced surgeons especially due to ocular akinesia, but this was not statistically significant. Besides, the eye globe can be easily stabilized by using forceps or rings and by the simultaneous use of phaco and a second device by the technique of bimanual phaco ^14-16.

Obtaining clear corneas in the first postoperative day is one of the greatest challenges in the surgical treatment of cataracts, i.e., trying to reduce as much as possible endothelial and incisional trauma during surgery ¹⁷. This indicates the importance of the easy application of the surgical technique and shorter surgical duration, which, in the present study, was not affected by the use of topical anesthesia.

The recovery time of the patients in the present study was similar to that is expected for phacoemulsification when compared with other studies, even those that used the anesthetic technique without sedation ¹⁸.

Some authors reported that since topical anesthesia is associated with faster recovery, reduces the length of stay of patients in the surgical ward and consequently reduces costs ¹⁹.

We did not observe a significant incidence of intra and postoperative complications, similar to what has been reported by other authors ¹⁵. In cases of rupture of the posterior capsule, only two in this study, a viscoelastic solution was injected in order to preserve spaces and facilitate mobilization of the lens and in the cases of epithelial edema, patients were under observation, according to the data in the medical literature ^20,21.

Topical anesthesia avoids the risks and local complications, such as periocular bleeding and optical nerve damage ²², ocular perforation ^23-26, retinal detachment, ptosis, temporary amaurosis or diplopia ²⁷ and systemic complications as respiratory depression ^22-28, seizures and coma, associated with the injection of anesthesia, both by the retrobulbar and peribulbar techniques, besides allowing faster return of the eye sight. This is the most adequate technique when the patient has any bleeding disorder ²⁹. It should be noted that the complications associated with the injection of anesthetics that were mentioned have a low incidence.

Although there are reports of cardiovascular problems due to the use of topical anesthesia with sedation, their frequency is much lower than in other methods ³⁰. Other studies demonstrated the cardiovascular safety of midazolam ³¹. In the present study, we decided to use low doses of midazolam, which demonstrated cardiovascular stability.

In this study, we observed a low incidence of nausea (4.8%) and vomiting (0.65%), despite the use of an opioid (alfentanil). A study with alfentanil and droperidol (which has anti-emetic properties) demonstrated a 15% incidence of nausea, much higher than the results of the present study ³². Other authors who used alfentanil associated with propofol in cataract removal surgeries with retrobulbar block did not observe nausea or vomiting in the recovery room or the following day ³³.

In this study, 0.5% proximetacaine was used as the local anesthetic. A study comparing proximetacaine with 0.5% tetracaine in patients undergoing phacoemulsification with incision without sutures, in forty patients selected randomly, the authors observed that the incidence of complaints of discomfort (pricking or stinging sensation) was lower in patients who used proximetacaine than in patients who used tetracaine, and this difference was statistically significant, but there was no loss in analgesic effect ³⁴. Proximetacaine has lower corneal toxicity than 0.4% oxybuprocaine and 2% and 4% lidocaine ^35,36.

In the present study, 42 patients complained of intraoperative pain, which represented 13.5% of the patients and is different than that reported in the literature that describes a higher incidence, around 60% of the patients undergoing fasciectomy with topical anesthesia without sedation and similar to the studies with retrobulbar ³⁷ and peribulbar ³⁸ anesthesia. Some authors reported that the incidence of intraoperative pain in patients with cataracts undergoing surgery by the subtenonian technique is lower than with topical anesthesia ⁸.

The effects of topical anesthesia are more pronounced on the cornea and conjunctiva, where nerve endings are free, reducing the discomfort caused by the infiltration of anesthetics ³⁹. On the other hand, the intraocular effect of the topical anesthetic is limited due to the poor penetration through the corneal epithelium and stroma associated with the lack of action on the ciliary ganglion requiring that the surgery should be done as fast as possible ⁴⁰.

Although pain depends on the emotional and cultural state of each individual ⁴¹, several patients reported discomfort during maneuvers that manipulate the iris or distend the ciliary body, such as with infusion of normal saline, with deepening of the anterior chamber, rotation of the nucleus and introduction of the intra-ocular lens ^42,43.

One of the technical disadvantages of the technique evaluated here is observed when the surgery has to last longer, as is the case of patients with extremely dense cataracts. Less experienced surgeons reported greater difficulty with this type of surgery due to the greater mobility of the eye ball ⁴⁴.

In one study, patients complained of ocular pain during the surgery and the author observed complications in some phases of the surgery due to ocular movement and he stated that topical anesthesia should not be indicated for patients who cannot cooperate during the surgery and those with hearing problems, when the nucleus of the lens is very hard and it is associated with small pupils and in combined surgeries of cataract and glaucoma ³⁰.

In this study, we did not observe significant gender difference regarding pain and consumption of alfentanil. The presence of pain as a function of gender is controversial. There is a tendency in the literature to state that the incidence of pain in several situations, such as the postoperative period translated by higher pain score and increased consumption of alfentanil is higher in females. Probable explanations may include the socialization process, in which females would be more fragile, besides hormonal differences that could modulate painful feelings ⁴⁵.

Evidence indicates that elderly patients do not complain of pain as often and require fewer analgesics than younger patients, which might have contributed for a low incidence of complaints of pain in this study, since most patients were in their sixties ⁴⁶.

We also observed that the total amount of alfentanil required varied from 125 µg to 1250 µg, with a mean dose of 537 µg. Some authors analyzed the use of different doses of alfentanil, 5, 10, and 15 µg.kg^-1, associated with propofol in 40 patients and concluded that the higher dose resulted in an increased incidence of respiratory depression around 40%. If one considers the mean weight of the patients in the present study, approximately 65 kg, a dose of 15 µg.kg^-1 would translate into 975 µg, higher than the average dose used here. Only 20 patients required total doses above 975 µg, and we did not observe the development of respiratory depression. The association midazolam-alfentanil instead of propofol-alfentanil might be another reason for the lack of any cases of respiratory depression ³¹. Midazolam has been safely used for sedation during diagnostic, therapeutic and outpatient surgical procedures ⁴⁷.

In another study, the author titrated the dose of alfentanil as coadjutant in cataract surgeries under retrobulbar block and observed an effective mean dose of 8.9 µg.kg^-1. Considering the mean weight of the patients, around 65 kg, the mean dose would be 578 µg, which is very close to the mean dose of our study ³³.

Other authors have evaluated the association of midazolam and alfentanil in cataract surgeries with retrobulbar block in 120 patients. The doses of midazolam varied from 0.5 to 1 mg and alfentanil varied from 250 to 500 µg. They observed a reduction in pain perception and reduction in oxygen saturation to 90% or lower in nine cases ⁴⁸. These data reinforce the sedation model used in this study.

The anesthetic or surgical technique did not have to be changed in the present study. However, in another study with 126 patients, 11 had to undergo peribulbar block and six, general anesthesia ³¹.

Most patients (306/98%) said they would use the same technique if they needed another surgery. The reduction in patient fear associated with the periocular injection (which is explained to the patient preoperatively when deciding which anesthetic technique will be used) associated with fast physical recovery and reduction in postoperative side effects can be considered the main factors responsible for the better acceptance of the technique. Some authors evaluated the degree of patient satisfaction with topical anesthesia and sedation with midazolam with different dosages than the ones used in this study and did not consider the technique to be superior ³¹. It was decided to use the classification bad, regular and good to evaluate the degree of patient satisfaction due to its objectivity and easy of application.

It was also observed that since patients leave the operating room without a dressing, which does not happen with the other techniques, could have influenced the choice of this technique by the patients.

The lack of comparison between topical anesthesia and phacoemulsification with another anesthetic technique performed by the same surgical team is another limitation of the present study, giving the results an observational and descriptive characteristic.

To conclude, topical anesthesia associated with sedation is easy to apply, practical, fast, effective and accessible to any health professional or institution involved in the treatment of cataracts, but patients should be carefully selected and it should be performed and followed by an anesthesiologist. Sedation had an important contribution, especially in anxious, apprehensive patients, since it tranquilized the patient allowing better cooperation. Good patient acceptance and low incidence of perioperative complications indicate that this technique can be disseminated and widely used, respecting the learning curve and abilities of each surgeon.

REFERENCES

Submitted em 26 de fevereiro de 2007

Accepted para publicação em 26 de outubro de 2007

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*

Received from Universidade Federal do Maranhão (UFMA), São Luís, MA

Publication Dates

• Publication in this collection
  17 Jan 2008
• Date of issue
  Feb 2008

History

• Accepted
  26 Oct 2007
• Received
  26 Feb 2007