Effect of different anesthetic agents on oculocardiac reflex in pediatric strabismus surgery

Surgical and anesthetic influences of the oculocardiac reflex in adults and children during strabismus surgery

One of the most common untoward occurrences during strabismus surgery at all ages is the oculocardiac reflex. Although typically easily treated, the sudden bradycardia or cardiac arrest may add a few gray hairs to ophthalmologists and anesthesiologists alike as it can be potentially fatal. This updated review of the literature and novel detailed treatment algorithm may prevent patient morbidity and mortality through proper recognition of at-risk patients and rapid treatment through proper communication between surgical and anesthesia physicians/providers.

Effect of Ice Slush on Reducing the Oculocardiac Reflex During Strabismus Surgery

BACKGROUND

The aim of this study was to explore whether ice slush (IS) causing local hypothermia can effectively inhibit the oculocardiac reflex (OCR) during strabismus surgery.

METHODS

This prospective, randomized, double-blind study included 58 patients with concomitant strabismus scheduled for lateral rectus (LR) recession under general anesthesia. Patients were randomly allocated to receive IS (IS group) or standard treatment (control group) with sterile saline at room temperature before surgery. OCR was defined as a sudden decrease in heart rate (HR) of >15% from baseline. If one incidence of the OCR was found in 1 patient in any stage (0/I/II/III), the patient was defined as an OCR responder, and the incidence of overall OCR was the incidence of OCR responders. The primary outcome was the incidence of overall OCR during all stages of the surgery, which was analyzed by the Z test and computed based on the absolute risk difference with 2-sided 95% confidence intervals (CIs) using the Newcombe method.

RESULTS

The overall OCR occurred in 19 of 29 patients (62.5% [95% CI, 45.7-82.1]) in the IS group and 28 of 29 patients (96.6% [95% CI, 82.2-99.9]) in the control group (absolute risk difference, -31.0% [95% CI, -49.4 to -11.0]; Z test, P < .001), which demonstrated that the incidence of overall OCR in IS group was significantly lower than that in the control group.

CONCLUSIONS

IS on the ocular surface causing local hypothermia is a promising and easily accessible method to reduce the overall OCR, which can improve the safety of strabismus surgery.

Sub-Tenon's bupivacaine injection is superior to placebo for pediatric strabismus surgery: A meta-analysis

BACKGROUND

The effect of post-operation sub-Tenon's bupivacaine injection for pediatric strabismus surgery is controversial. The objective of this meta-analysis is to compare the outcome of sub-Tenon injection of bupivacaine and placebo duringstrabismus surgery.

METHODS

We searched the databases (Pubmed, Cochrane library and EMBASE) and reference lists systematically. Randomized controlled trials (RCTs) comparing sub-Tenon's bupivacaine and placebo injection for pediatric strabismus surgery were included. The methodological quality was evaluated by the Cochrane risk of bias (ROB) tool. Outcome measurements were pain score, oculocardiac reflex (OCR), additional drug consumption and related complications. RevMan 5.4 was used for the statistical analysis and graph preparation. For the outcomes that are not suitable for statistical analysis, descriptive analysis was performed.

RESULTS

A total of 5 RCTs with 217 patients were finally identified and analyzed. Sub-Tenon's bupivacaine injection showed pain relief within 30 min after operation. But with the extension of time, the analgesic effect gradually disappeared at 1 h. It can reduce the incidence of OCR, vomiting and supplementary drug requirements. However, in terms of nausea, there is no difference between the two groups.

CONCLUSION

Sub-Tenon's bupivacaine injection can relieve short-term postoperative pain, reduce the incidence of OCR and vomiting, and reduce the use of supplementary drugs in strabismus surgery.

Anesthesia for ophthalmic surgery: an educational review

PURPOSE

Selecting an anesthetic agent for ophthalmic surgery has crucial implications for the surgeon, anesthesiologist, and patient. This educational review explores the common classes of anesthesia used in ophthalmology. Additionally, we discuss the considerations unique to cataract, glaucoma, strabismus, orbital, oculoplastic, and ocular trauma surgeries.

METHODS

A comprehensive Embase search was performed using combinations of the subject headings "anesthesia", "eye surgery", "ophthalmology" and "cataract extraction", "glaucoma", "strabismus", "vitreoretinal surgery", "retina surgery", "eye injury", and "eyelid reconstruction".

RESULTS

Topical anesthetics are the most commonly used form of ocular anesthesia, used in both an office and surgical setting, and carry a minimal side effect profile. Notably, topical anesthetics offer analgesia, but do not provide akinesia or amnesia. Regional blocks, such as are sub-Tenon's, peribulbar, and retrobulbar blocks, are used when akinesia is required in addition to analgesia. Recently, sub-Tenon's blocks have recently gained popularity due to their improved safety profile compared to other regional blocks. General anesthesia is considered for long, complex surgery, surgery in patients with multiple comorbidities, surgery in young pediatric patients, or surgery in patients intolerant to local or regional anesthetic.

CONCLUSION

Anesthetizing the eye has rapidly evolved in recent years, supporting the safety, efficacy and comfort of ocular surgery. Since there are many viable options of anesthetics available for ophthalmic surgery, a robust understanding of the patients needs, the skill of the surgical team, and surgery-specific factors ought to be considered when creating an anesthetic plan for surgery.

Hydroxyzine Dihydrochloride Premedication Is a Necessity for Pediatric Patients Undergoing Strabismus Surgery: An Observational Prospective Clinical Trial

Objective

In this single-blind, observational prospective clinical trial, we aimed to determine and compare the effects of premedication with hydroxyzine plus midazolam and midazolam alone on the incidence of oculocardiac reflex (OCR).

Methods

Forty-five patients were divided into three groups. Group M received 0.5 mg/kg midazolam alone, Group H received 0.5 mg/kg hydroxyzine plus 0.5 mg/kg midazolam, and Group HM received 1 mg/kg hydroxyzine plus 0.5 mg/kg midazolam. The Ramsay Sedation Scale (RSS), the heart rates (HR1: after induction of anesthesia; HR2: before retraction of orbital muscle; and HR3: right after retraction of orbital muscle), the muscles with OCR, and the incidence of OCR (20% decrease of the HR right after the traction) were recorded and compared between the three groups.

Results

The mean HR1, HR2, and HR3 values were significantly increased (p=0.002, p < 0.001, p < 0.001) and the incidence of OCR (p=0.004) was significantly decreased in Group H and in Group HM (for all, p < 0.01) compared to Group M. The most common orbital muscle in which OCR occurred was the rectus medialis.

Conclusion

Premedication with a combination of 0.5 or 1 mg hydroxyzine with 0.5 mg midazolam significantly reduced the incidence of OCR compared to premedication with midazolam alone. This study was registered on https://clinicaltrials.gov/ with number NCT03806270.

Profound trigeminocardiac reflex from lingual nerve stimulation: a case report

Trigeminocardiac reflex (TCR) is a well-known brainstem reflex that manifests as hypotension, bradycardia, dysrhythmia, and asystole when stimulation is applied to a branch of the trigeminal nerve. Most commonly associated with ophthalmic, orbital, and neurologic surgeries, mandibular division and oral cavity variants occur far less frequently. Here, we describe a case of asystolic TCR elicited by lingual nerve stimulation. This case highlights the role of specific anesthetic medications in modulating this phenomenon and reinforces the need for early recognition and clear communication in case of its occurrence. Anesthesia providers must consider discontinuing or avoiding certain medications when clinically appropriate, even during low TCR-risk procedures.

Comparison of the ED50 propofol requirements during the insertion of laryngeal mask airway Ambu AuraFlex with Ambu AuraOnce in children undergoing strabismus surgery

WHAT IS KNOWN AND OBJECTIVE

Optimal airway management is crucial in strabismus surgery due to the inaccessibility of the airway throughout the procedure. Laryngeal mask airway offers advantages over tracheal intubation in ophthalmic surgery as it does not increase the intraocular pressure. The purpose of this study was to determine the median effective dose of propofol required, when combined with 0.2 µg/kg of sufentanil, for smooth insertion of Ambu AuraFlex in the first attempt in children undergoing strabismus surgery, and to compare it with that for Ambu AuraOnce.

METHODS

Forty-three paediatric patients undergoing strabismus surgery under general anaesthesia were recruited. For induction, the initial dosage of propofol was 2 mg/kg in the AuraOnce group or 3 mg/kg in the AuraFlex group. In accordance with Dixon's up-and-down method, the dose of propofol for consecutive patients in each group was adjusted in increments or decrements of 0.25 mg/kg based on the previous patient's "three-point, six-category scale" response to the first attempt of insertion of the randomized device. Insertion of the device was attempted when the bispectral index was ≤60 for 5 s after propofol administration without the use of neuromuscular blocking agents.

RESULTS AND DISCUSSION

The median effective dose (95% confidence interval) of propofol was significantly lower in the Ambu AuraOnce group than in the Ambu AuraFlex group (1.92 [1.50-2.32] mg/kg vs. 2.98 [2.49-3.94] mg/kg; p = 0.002). The incidence of dislodgement of the device was significantly higher with the use of the Ambu AuraOnce than with the use of AuraFlex (p = 0.023), whereas insignificant differences were observed between the two groups in the incidence of other perioperative adverse events.

WHAT IS NEW AND CONCLUSION

Ambu AuraFlex requires a significantly higher dose of propofol for insertion and provides more effective and stable airway management in strabismus surgery than AuraOnce.

Perioperative dexmedetomidine reduces emergence agitation without increasing the oculocardiac reflex in children: A systematic review and meta-analysis

BACKGROUND

Intravenous dexmedetomidine (DEX) has been used to prevent emergence agitation (EA) in children. The aim of this meta-analysis was to evaluate whether DEX decreases EA incidence without augmenting oculocardiac reflex (OCR) in pediatric patients undergoing strabismus surgery.

METHODS

We searched PubMed, EMBASE, Chinese National Knowledge Infrastructure (CNKI), Wan Fang, and the Cochrane Library to collect the randomized controlled trials (RCTs) investigating the effects of intraoperative DEX in children undergoing strabismus surgery from inception to October 2019. Postoperative Pediatric Agitation and Emergence Delirium (PAED) score, postoperative EA, extubation or laryngeal mask airway (LMA) removal time, postanesthetic care unit (PACU) stay time, OCR, and postoperative vomiting (POV) were evaluated.

RESULTS

11 RCTs including 801 patients were included in this study. Compared with control group, intravenous DEX significantly reduced postoperative PAED score (WMD, 3.05; 95% CI: -3.82 to -2.27, P = .017) and incidences of postoperative EA 69% (RR, 0.31; 95% CI: 0.17 to 0.55, P < .00) and POV (RR, 0.28; 95% CI: 0.13 to 0.61, P = .001). Furthermore, the use of DEX significantly delayed extubation or LMA removal time (WMD, 2.11; 95% CI: 0.25 to 3.97, P < .001). No significant difference was found in the incidence of ORC and PACU stay time.

CONCLUSION

Intravenous DEX reduced the incidences of EA without increasing OCR in pediatric patients undergoing strabismus surgery. Meanwhile, DEX infusion decreased the incidence of POV in children.

Desflurane anesthesia compared with total intravenous anesthesia on anesthesia-controlled operating room time in ambulatory surgery following strabotomy: a randomized controlled study

BACKGROUND

Ophthalmic ambulatory surgery is preferred to be performed under general anesthesia either by total intravenous anesthesia (TIVA) or by inhalational anesthesia to increase the patient comfort. However, anesthesia-controlled time (ACT) can cause increased non-operative operating room (OR) time which may adversely affect the ORs efficiency. This study was aimed to compare the ACT of desflurane with that of propofol-remifentanil in strabismus ambulatory surgery.

METHODS

From November 2016 to December 2017, a total of 200 strabismus patients (aged 18-60 years old, and scheduled for elective ambulatory surgery at Zhongshan Ophthalmic Center) were randomly assigned to receive either propofol-based TIVA (group TIVA) or desflurane anesthesia (group DES) for maintenance of anesthesia. The primary outcome was the extubation time. Secondary outcomes included surgical time, anesthetic time, OR exit time, and Phase I and II recovery time. The intraoperative incidences of hypotension, bradycardia and oculocardiac reflex (OCR), and the incidences of any post-operative complications were recorded. Mann-Whitney U test and Chi-square or Fisher exact tests were used to compare the two groups.

RESULTS

We found that the extubation time (5.5 [3.9-7.0] vs. 9.7 [8.5-11.4] min, P < 0.001) and the incidence of prolonged time to extubation (0 vs. 6%, P = 0.029) in the DES group were significantly decreased compared with those in the TIVA group. The patients in the DES group displayed shorter OR exit time as compared with that in the TIVA group (7.3 [5.5-8.7] vs. 10.8 [9.3-12.3] min, P < 0.001). The patients using desflurane exhibited more stable hemodynamics during surgery than the patients using propofol-based TIVA, as demonstrated by lower incidences of hypotension (1% vs. 22%, P < 0.001), bradycardia (2% vs. 13%, P = 0.002), and OCR (17% vs. 44%, P < 0.001).

CONCLUSION

DES enhanced the ophthalmic OR efficiency by reducing the extubation time and OR exit time, and provided more stable hemodynamics intra-operatively than TIVA in patients undergoing strabismus ambulatory surgery.

TRIAL REGISTRATION

ClinicalTrials.gov, No. NCT02922660; https://clinicaltrials.gov/ct2/show/NCT02922660?id=NCT02922660&draw=2&rank=1.

Maxillomandibulocardiac reflex in a dog

Background

The trigeminocardiac reflex (TCR) is a brainstem reflex that may be observed in anaesthesia during surgical procedures stimulating the intracranial or peripheral portion of the trigeminal nerve. The peripheral TCR is divided into the oculocardiac reflex and the maxillomandibulocardiac reflex based on the affected sensory branches of the trigeminal nerve. In veterinary medicine the oculocardiac reflex has been described, however the maxillomandibulocardiac reflex has never been reported.

Case presentation

A 5-year-old male Epagneul Breton was presented for surgical management of an upper lip mass. During surgery, a sudden severe bradycardia and a decrease in systemic arterial blood pressure developed. The occurrence of a maxillomandibulocardiac reflex was suspected on the basis of the temporary link between surgical stimulation and haemodynamic changes. Three doses of atropine were given before starting a dopamine infusion due to lack of response. The dopamine infusion normalized heart rhythm and blood pressure. The dog recovered uneventfully and he was discharged 24 h later with a sinus rhythm and no sign of recurrence of arrhythmias.

Conclusion

The TCR is a rare but potentially life-threatening complication of procedures involving the sensory areas innervated by the three branches of the trigeminal nerve and it may cause bradycardia with hypotension. The use of a β1-adrenergic receptor agonist such as dopamine may be indicated in cases of a refractory response to the conventional treatment with atropine.

Prospective evaluation of anesthetic protocols during pediatric ophthalmic surgery

PURPOSE

To date, no protocol of anesthesia for pediatric ophthalmic surgery is unanimously recognized. The primary anesthetic risks are associated with strabismus surgery, including oculocardiac reflex, postoperative nausea and vomiting, and postoperative pain.

METHODS

This was a prospective, monocentric, observational study conducted in a tertiary pediatric ophthalmic unit. Our anesthetic protocol for strabismus surgery included postoperative nausea and vomiting prevention using dexamethasone and ondansetron. No drug-based prevention of oculocardiac reflex or local/locoregional anesthesia was employed.

RESULTS

A total of 106 pediatric ophthalmic surgeries completed between November 2015 and May 2016 were analyzed. The mean patient age was 4.4 (range: 0.2-7.3, standard deviation: 2.4) years. Ambulatory rate was 90%. Oculocardiac reflex incidence was 65% during strabismus surgery (34/52), 50% during congenital cataract surgery (4/8), 33% during intramuscular injection of botulinum toxin (1/3), and 0% during other procedures. No asystole occurred. Postoperative nausea and vomiting incidence was 9.6% after strabismus surgery (5/52) and 0% following the other procedures. One child was hospitalized for one night because of persistent postoperative nausea and vomiting. Postoperative pain generally occurred early on in the recovery room and was quickly controlled. Its incidence was higher in patients who underwent strabismus surgery (27%) than in those who underwent other procedures (9%).

CONCLUSION

Morbidity associated with ophthalmic pediatric surgery is low and predominantly associated with strabismus surgery. The benefit-risk ratio and cost-effectiveness of oculocardiac reflex prevention should be questioned. Our postoperative nausea and vomiting rate is low, thanks to the use of a well-managed multimodal strategy. Early postoperative pain is usually well-treated but could probably be more effectively prevented.

The Effect of Sub-Tenon's Bupivacaine on Oculocardiac Reflex during Strabismus Surgery and Postoperative Pain: A Randomized Clinical Trial

PURPOSE

Oculocardiac reflex (OCR), defined as bradycardia induced by manipulation of extraocular muscles, is a serious complication during strabismus surgery for which prevention and proper management is required. In the present study, we investigated the efficacy of sub-Tenon injection of bupivacaine for prevention of OCR and postoperative pain.

METHODS

A prospective randomized controlled clinical trial was conducted. Fifty patients who were candidates for strabismus surgery were randomized into case (sub-Tenon's bupivacaine injection) or control (normal saline injection) groups. Standard strabismus surgery was performed for all cases. Occurrence and severity of OCR (primary outcome) and postoperative pain (using the Visual Analog Scale) were compared between the two groups.

RESULTS

Both incidence (32% vs. 100%; P = 0.002) and severity of OCR (mean heart rate decrease, 10.1 vs. 38.7 beats/minute; P < 0.001) were significantly lower in the study group compared to those in the control group. Postoperative pain scores were significantly lower in the case group than in the control group (mean score, 2.8 vs. 5.9 at 60 minutes after surgery; P < 0.001).

CONCLUSIONS

Sub-Tenon injection of bupivacaine as a local anesthetic can significantly prevent OCR and decrease the severity of bradycardia. This technique can also diminish postoperative pain in patients who underwent strabismus surgery.

Dexmedetomidine Injection during Strabismus Surgery Reduces Emergence Agitation without Increasing the Oculocardiac Reflex in Children: A Randomized Controlled Trial

Objective

Dexmedetomidine is known to reduce the incidence of emergence agitation, which is a common complication after inhalational anesthesia like sevoflurane or desflurane in children. However, the dose of dexmedetomidine used for this purpose is reported variously and the most effective dose is not known. In this study, we tried to find the most effective dose of dexmedetomidine to reduce the incidence of emergence agitation in children undergoing strabismus surgery without the complications like oculocardiac reflex (OCR) or postoperative vomiting.

Methods

We randomized 103 pediatric patients aged 2–6 years and undergoing elective strabismus surgery into four groups. Anesthesia was induced with sevoflurane and maintained with desflurane. At the start of induction, dexmedetomidine, delivered at 0.25, 0.5, or 1 μg/kg, or saline was infused intravenously in the D0.25, D0.5, D1 groups, respectively. The primary outcome measure was the incidence of emergence agitation and the secondary outcome measure was the incidence of intraoperative OCR, postoperative vomiting, and desaturation events.

Results

The incidence of emergence agitation was 60, 48, 44, and 21% (P = 0.005) and the incidence of intraoperative OCR was 36, 36, 36, and 37% (P = 0.988) in the control, D0.25, D0.5, and D1 groups, respectively. And, postoperative vomiting rate and desaturation events were low in the all groups.

Conclusion

Dexmedetomidine decreased the incidence of emergence agitation without increasing intraoperative oculocardiac reflex. Dexmedetomidine delivered at 1 μg/kg was more effective at reducing emergence agitation than lower doses in children undergoing strabismus surgery under desflurane anesthesia.

Trial Registration

Clinical Research Information Service KCT0000141

[PONV after strabismus surgery : Risk adapted prophylaxis?]

BACKGROUND

Following strabismus surgery, patients frequently develop variable degrees of postoperative nausea and vomiting (PONV). These symptoms cause discomfort and result in serious complications such as intramuscular bleeding and subconjunctival hemorrhage. In children long lasting PONV can lead to and electrolyte imbalance and dehydration. A prolonged course of recovery is the consequence. For the hospital, PONV can also involve negative economic impacts because of a damaged public reputation of the institution. There is still an ongoing debate on wether prophylaxis of PONV is necessary and how the prophylaxis of PONV should be performed. On one hand, there are proponents of a liberal prophylaxis. These intend to treat almost all patients regardless of their individual risk for PONV. On the other hand, opponents point out that every medication has to be indicated individually. In their view, risk scores should be the base of a risk-adapted approach.

OBJECTIVES

The aim of the study was to reduce the frequency of PONV by using an anesthetic technique adapted to the individual risk for PONV. Until now, all trials studying the efficiency of a score-based antiemetic prophylaxis were performed on adult patients. In this study, a risk-adapted approach was evaluated on children for the first time.

PATIENTS AND METHODS

In 92 patients, the incidence of PONV was analyzed after strabismus surgery. Before surgery we evaluated the risk factors for PONV according to the POVOC score in children (n = 45, 49 %) and the Apfel's score in adults (n = 47, 51 %). Patients with 0-2 risk factors received a balanced anesthesia (n = 47, 51 %). Those with 3-4 risk factors were operated in total IV anesthesia (TIVA) with propofol (n = 45, 49 %). In addition, as an antiemetic prophylaxis, 0.15 mg/kg dexamethason and 0.1 mg/kg ondansetron were applied in the latter patients. we documented the symptoms and severity of PONV 2, 6 and 24 h after surgery by means of a standardized questionnaire for PONV (Wengritzky-Score).

RESULTS

The incidence of PONV was 17 % (n = 16) in all of the patients. The incidence in low-risk patients receiving a BA without prophylaxis were 21 % in adults and 38 % in children. Of the patients at high risk for PONV receiving the multimodal antiemetic approach 8 % (adults) and 9 % (children) suffered from PONV. The combination of TIVA and antiemetics could reduce the incidence of PONV compared to the predicted values in a clinically relevant manner (OR = 0.26, KI: 0.76-0.87).

CONCLUSION

The overall incidence could be reduced to a level below 20 %. Particularly in patients with a high risk of PONV, TIVA could clearly reduce the incidence. However, the incidence in patients with 2 risk factors is still high (30-39 %). Therefore, it is important to reconsider the effort involved with risk screening and individually adapting anesthesia. Risk stratification means a pre- and perioperative effort. Therefore, we advocate a more liberal approach for PONV prophylaxis.

The effect of anesthesia depth on the oculocardiac reflex in strabismus surgery

The aim of this study was to investigate the effect of the bispectral index (BIS) guided depth of anesthesia to inhibition of the oculocardiac reflex (OCR) during pediatric strabismus surgery. Patients between the ages of 3 and 16 years who were scheduled for elective strabismus surgery were randomly assigned to two groups. In Group 1 (n: 32), the BIS values of the patients were maintained at <50; in Group 2 (n: 28), the BIS values of the patients were maintained at levels greater than or equal to 50 with 4-7 % desflurane in a 50 % O₂-air mixture by titrating the concentration during the surgery. The heart rates, presence of dysrhythmia, anticholinergic drug usage and the type of the operated extra ocular muscle were recorded. The incidence of OCR was 25 % in Groups 1 and 64.3 % in Group 2, (p < 0.05). Moreover, the incidence of OCR in group 2 was higher in medial rectus (MR) traction (78.9 %) than in lateral rectus (LR) traction (33.3 %) (p = 0.035), with no significant difference in Group 1 between MR (21.1 %) and LR (26.7 %) tractions (p = 0.83). We found that the lower BIS values are associated with the lower incidence of OCR in pediatric patients undergoing strabismus surgery. And our findings confirmed that the deeper anesthesia has a protective effect against the OCR.

Trigeminocardiac reflex: differential behavior and risk factors in the course of the trigeminal nerve

ABSTRACT; The trigeminocardiac reflex (TCR) is a brainstem reflex describing the acute hemodynamic perturbations in neurosurgical patients. The roles of different anatomic locations of this reflex arc on end responses have been found to be variable. In this article, we have highlighted the role and importance of different TCR pathway (peripheral vs central) mechanisms, their manifestations and the various risk factors associated with these. In addition, new insights into various other non-neurosurgical conditions, in special relation to neurointerventional procedures, are also presented in this article. This study is a narrative review based on a PubMed/Google search (from 1 January 1970 to 31 March 2013) on this topic. The common manifestations, such as hypotension and bradycardia, are vagal-dominated responses; however, unusual manifestations, such as hypertension and tachycardia, signify the involvement of the sympathetic nervous system. In addition, there is a complex interaction of the various sensory receptors at the Gasserian ganglion, and this is responsible for the different presentations. There are many surgical as well as nonsurgical risk factors associated with TCR. Interestingly, TCR may affect functional outcome and has been found to be involved in some normal physiological mechanisms, including bruxism. TCR is a complex neurophysiological reflex and there are variable presentations depending upon the peripheral or central stimulation surrounding the Gasserian ganglion. We suggest, for the first time, that if the TCR is initiated at the Gasserian ganglion, it reacts in a different manner from the better-known central or peripheral TCR.

Trigeminocardiac reflex in neurosurgical practice: Report of two new cases

BACKGROUND

Systemic hypotension, cardiac dysrhythmia especially bradycardia, apnea, and gastric hypermotility occurring presumably after stimulation of any of the sensory branches of trigeminal nerve are coined as trigeminocardiac reflex (TCR). Neither enough is known about the predisposing factors in relation with the intraoperative occurrence of this life threatening reflex, nor about the exact pathophysiology of its brain stem pathway. ENCOUNTERING TWO CASES OF BRADYCARDIA AND HYPOTENSION DURING SURGERY ENCOURAGED THE AUTHORS TO: (1) report these two cases and review similar reports in the relevant literature, (2) discuss the suggested mechanisms for such an event, and (3) report the result of a prospective cohort of precisely checked cases in a sister article, to remind the younger neurosurgical community of a possible and bothering even mortal, but avoidable complication in their everyday practice.

CASE DESCRIPTION

The first case was a 71-year-old male who developed bradycardia and hypotension while packing his large sella tursica with autologous fat after removing a large nonfunctional pituitary adenoma transsphenoidally to prevent cerebrospinal fluid leakage. The changes in his vital signs were detected and controlled rapidly. The second case was a 52-year-old female who underwent right pterional craniotomy for right clinoidal meningioma. She developed severe bradycardia and hypotension after skin closure completed and just when the subgaleal drain was connected to the aspirating bag and negative pressure maintained in the subgaleal region. Both cases could be managed successfully after on time detection of such life threatening complication and proper management.

CONCLUSION

WE DO NOT INTEND ONLY TO ADD TWO NEW CASES OF TCR OCCURRING IN THE PERIOPERATIVE PERIOD IN NEUROSURGICAL PRACTICE, BUT WE WISH TO RAISE THE QUESTION: (a) what could be the predisposing factors for development of such issue for better handling of the problem and (b) stress upon careful continuous mapping of the vital signs during surgery and even till very late after operation.

Effect of ketamine and midazolam on oculocardiac reflex in pediatric strabismus surgery

Background

The oculocardiac reflex (OCR) can be elicited during manipulation of the orbital structures in the strabismus correction surgery. A sinus bradycardia is the most common manifestation of OCR; and cardiac dysrhythmia and asystole may also occur. Various efforts to reduce OCR have been attempted, but without coherent outcome results.

Methods

Sixty one children, undergoing elective strabismus surgery, were randomly allocated into 2 groups: Group K received ketamine 1.0 mg/kg; and Group M received midazolam 0.15 mg/kg for induction of anesthesia. Anesthesia was maintained with 1-1.3 MAC of sevoflurane with 50% N₂O in O₂. Heart rate and blood pressure were measured 30 seconds before extraocular muscle (EOM) traction and immediately after traction. The OCR was defined as a decrease in heart rate more than 20% of the baseline heart rate, following manipulating EOM. Postoperative nausea and vomiting (PONV) and emergence agitation (EA) were assessed in postanesthetic care unit (PACU).

Results

Blood pressure before tightening EOM in Group K was higher than that in Group M (P < 0.05). However Δ HR (2.7 ± 15% vs. - 0.9 ± 16%) and incidence of OCR (10.0% vs. 19.4%) after traction an EOM were not different between the two groups. The occurrence of PONV (6.7 vs. 9.7%) and EA (30.0% vs. 22.6%) were similar.

Conclusions

Ketamine does not reduce the incidence of OCR compared with midazolam in pediatric strabismus surgery. In addition, ketamine does not increase the incidence of PONV and EA. In conclusion, it is reliable to use ketamine in pediatric strabismus surgery.

Central trigeminocardiac reflex in pediatric neurosurgery: a case report and review of the literature

Introduction

Trigeminocardiac reflex is a well-known phenomenon in neurosurgery, craniofacial surgery, ophthalmology and interventional neuroradiology. Even though the trigeminocardiac reflex has become an important factor in skull base surgery and neurosurgery, the central form of trigeminocardiac reflex has only been described in adult subpopulations until now.

Case presentation

We present a clear form of repetitive trigeminocardiac reflex expressed during revision surgery of a giant (110×61mm) right temporoparietal meningioma in an 18-month-old male Caucasian patient. After cessation of the surgical stimulus, his heart rate and mean arterial blood pressure returned to normal physiological levels. The further follow-up was uneventful.

Conclusion

Our case demonstrates that the central trigeminocardiac reflex also exists in pediatric patients, especially if manipulating trigeminal innervated structures or around the nerve itself. Whether the incidence and the behavior of the trigeminocardiac reflex is similar in pediatric neurosurgery compared with adult patients has to be shown in further studies.

Dexmedetomidine use during strabismus surgery in agitated children

OBJECTIVE

We aimed to investigate the effects of dexmedetomidine premedication before intravenous infusion of ketamine in agitated children undergoing strabismus surgery.

SUBJECTS AND METHODS

We enrolled 60 agitated pediatric patients, aged 4.5-11 years. The patients were randomly allocated to one of two anesthesia regimens. Group D patients were premedicated with a single dose of intravenous dexmedetomidine 0.5 μg/kg whereas group P patients received a placebo. Patients in both groups were administered intravenous ketamine 1 mg/kg i.v. over 1 min followed by a continuous infusion of ketamine 1-3 mg/kg/h i.v. (n = 30). Patients were intubated after receiving fentanyl 1 μg/kg and rocuronium bromide 0.5 mg/kg.

RESULTS

21 (70%) patients in group D did not show the oculocardiac reflex (OCR) versus 7 (23%) in group P (p = 0.0006). The preoperative and postoperative agitation scores (p = 0.0001 and p = 0.03, respectively), the score on the Faces Pain Scale during awakening [3.0 (interquartile range, IQR 2.0-4.0) in group D and 0.0 (IQR 1.0-2.25) in group P] (p = 0.001) and at the 60th postoperative minute [IQR 2.0 (1.5-3.0) in group D and 2.0 (IQR 1.5-3.0) in group P] (p = 0.004), sore throat (26.6% in group D and 60% in group P) (p = 0.01) and analgesic requirement (20% in group D and 53% in group P) (p = 0.01) in group P were significantly higher than in group D. The Ramsay Sedation Score (RSS) in group D was significantly higher than in group P during awakening [2.0 (2.0-2.0) in group D and 4.5 (4.0-5.0) in group P] (p = 0.0001).

CONCLUSION

Dexmedetomidine premedication followed by intravenous infusion of ketamine was effective in decreasing OCR, agitation, pain, analgesic requirement in agitated children undergoing strabismus surgery.

Anesthetic management for pediatric strabismus surgery: Continuing professional development

PURPOSE

Strabismus surgery is one of the most common pediatric ophthalmic procedures. The purpose of this continuing professional development module is to update physicians on the anesthetic considerations of pediatric patients undergoing strabismus surgery.

PRINCIPAL FINDINGS

The preoperative assessment is important, as patients undergoing strabismus surgery may have an associated neuromuscular disorder, congenital syndrome, or cardiac disease. Malignant hyperthermia is no longer considered as being an issue associated with strabismus. The laryngeal mask airway is used frequently and has been shown as being associated with a low incidence of complications in strabismus surgery. The anesthesia technique can be adapted to decrease the incidence of the oculocardiac reflex and the oculorespiratory reflex, and the use of anticholinergic prophylaxis remains debatable. Since patients are at high risk for postoperative nausea and vomiting (PONV), combination anti-emetic therapy is recommended using dexamethasone and ondansetron. Metoclopramide was not found to provide additional benefit when combined with other anti-emetics. Droperidol is effective, but there remains a black box warning for dysrhythmias. Effective analgesics in this patient population include acetaminophen, nonsteroidal anti-inflammatory drugs, peribulbar blocks, and subtenon blocks. Topical tetracaine drops have demonstrated mixed results, and topical nonsteroidal anti-inflammatory drops were found not to be effective. The use of opioids should be minimized due to the increased incidence of PONV.

CONCLUSIONS

To provide optimal care for the pediatric patient undergoing strabismus surgery, it is important to understand the unique anesthetic considerations for strabismus surgery and to appreciate how each decision regarding the anesthetic technique can alter these considerations.