[Peripheral nerve block and rebound pain: literature review]

BACKGROUND AND OBJECTIVES

To investigate, describe, and assess the phenomenon of "rebound pain" as a clinically relevant problem in anesthetic practice.

CONTENT

The phenomenon of "rebound pain" has been demonstrated and described as a very severe pain, which occurs after a peripheral nerve block resolution with the recovery of sensitivity. The incidence of rebound pain is unknown. Usually, it occurs between 12 to 24hours after surgery and adversely affecting sleep quality. It is not yet possible to establish a mechanism as a definitive cause or trigger factor of rebound pain. Studies suggest that rebound pain is a side effect of peripheral nerve blocks, despite their effectiveness in pain control. Currently, the extent and clinical significance of rebound pain cannot be well determined due to the lack of large prospective studies.

CONCLUSION

Rebound pain assessment should always be considered in clinical practice, as it is not a rare side effect of peripheral nerve blocks. There are still many challenging questions to be answered about rebound pain, so large prospective studies are needed to address the issue. For prevention, the use of peripheral nerve block techniques that avoid nerve damage and adequate perioperative analgesia associated with patient education on the early administration of analgesics, even during the period of analgesia provided by peripheral nerve block, is recommended. A better understanding of the "rebound pain" phenomenon, its pathophysiology, associated risk factors, and long-term consequences may help in developing more effective preventive strategies.

[Anesthesia for muscle biopsy to test susceptibility to malignant hyperthermia]

INTRODUCTION

Malignant hyperthermia is an autosomal dominant pharmacogenetic disorder, characterized by hypermetabolic crisis triggered by halogenated anesthetics and/or succinylcholine. The standard method for diagnosing malignant hyperthermia susceptibility is the in vitro muscle contracture test in response to halothane-caffeine, which requires muscle biopsy under anesthesia. We describe a series of anesthetic procedures without triggering agents in malignant hyperthermia, comparing peripheral nerve block and subarachnoid anesthesia.

METHOD

We assessed the anesthetic record charts of 69 patients suspected of malignant hyperthermia susceptibility who underwent muscle biopsy for in vitro muscle contracture in the period of 7 years. Demographic data, indication for malignant hyperthermia investigation, in vitro muscle contracture test results, and surgery/anesthesia/recovery data were analyzed.

RESULTS

Sample with 34±13.7 years, 60.9% women, 65.2% of in vitro muscle contracture test positive. Techniques used: peripheral nerve blocks - lateral femoral and femoral cutaneous, latency 65±41minutes - (47.8%); subarachnoid anesthesia (49.3%), and total venous anesthesia (1.4%). There was 39.4% failure of peripheral nerve block and 11.8% of subarachnoid anesthesia. Adverse events (8.7%) occurred only with subarachnoid blockade (bradycardia, nausea, and transient neurological syndrome). All patients remained in the post-anesthesia care unit until discharge. Age and weight were significantly higher in patients with blockade failure (ROC cut-off point of 23.5 years and 59.5kg) and blockade failure was more frequent in the presence of increased idiopathic creatine kinase.

CONCLUSION

Anesthesia with non-triggering agents has been shown to be safe in patients with malignant hyperthermia susceptibility. Variables such as age, weight, and history of increased idiopathic creatine kinase may be useful in selecting the anesthetic technique for this group of patients.

[Peribulbar block combined with general anesthesia in babies undergoing laser treatment for retinopathy of prematurity: a retrospective analysis]

BACKGROUND AND OBJECTIVES

Currently there is no agreement regarding which one is the most adequate anesthetic technique for the treatment of retinopathy of prematurity. Peribulbar block may reduce the incidence of oculocardiac reflex and postoperative apnea. The goal of this study was to report the outcomes of peribulbar block, when combined with general anesthesia, for the laser treatment for retinopathy of prematurity, in premature babies.

METHODS

A retrospective analysis of anesthetic records of all babies who underwent laser treatment for retinopathy of prematurity from January 2008 through December 2015 in a tertiary hospital was performed.

RESULTS

During that period a total of six babies was submitted to laser treatment for retinopathy of prematurity, all under peribulbar block combined with general anesthesia. A single infratemporal injection of 0.15mL.kg^-1 per eye ropivacaine 1% or 0.75% was performed. At the end of the procedure, all babies resumed spontaneous ventilation. No perioperative complications were reported.

CONCLUSIONS

Peribulbar block was a safe anesthetic technique in our sample considered.

Treatment of patients with painful blind eye using stellate ganglion block

BACKGROUND AND OBJECTIVES

management of pain in painful blind eyes is still a challenge. Corticosteroids and hypotensive agents, as well as evisceration and enucleation, are some of the strategies employed so far that are not always effective and, depending on the strategy, cause a deep emotional shock to the patient. Given these issues, the aim of this case report is to demonstrate a new and viable option for the management of such pain by treating the painful blind eye with the stellate ganglion block technique, a procedure that has never been described in the literature for this purpose.

CASE REPORT

six patients with painful blind eye, all caused by glaucoma, were treated; in these patients, VAS (visual analogue scale for pain assessment, in which 0 is the absence of pain and 10 is the worst pain ever experienced) ranged from 7 to 10. We opted for weekly sessions of stellate ganglion block with 4 mL of bupivacaine (0.5%) without vasoconstrictor and clonidine 1 mcg/kg. Four patients had excellent results at VAS, ranging between 0 and 3, and two remained asymptomatic (VAS=0), without the need for additional medication. The other two used gabapentin 300 mg every 12h.

CONCLUSION

currently, there are several therapeutic options for the treatment of painful blind eye, among which stand out the retrobulbar blocks with chlorpromazine, alcohol and phenol. However, an effective strategy with low rate of serious complications, which is non-mutilating and improves the quality of life of the patient, is essential. Then, stellate ganglion block arises as a demonstrably viable and promising option to meet this demand.