Perioperative bradycardia and asystole: relationship to vasovagal syncope and the Bezold-Jarisch reflex

Total spinal anaesthesia following obstetric neuraxial blockade: a narrative review

BACKGROUND

Total spinal anaesthesia (TSA) is an emergency caused by high neuraxial blockade. It is a recognised complication of all neuraxial techniques in obstetric anaesthesia. Its incidence and outcomes have not been evaluated. There is compelling evidence that TSA continues to be a problem in contemporary practice, having the capacity to cause significant morbidity and mortality if not recognised early and promptly treated. This review based on a literature search aims to clarify the epidemiology of TSA, summarise its pathophysiology, and identify risk factors and effective treatments.

METHODS

We performed a literature search using PubMed, Web of Science and Google Scholar databases using specified search terms for materials published using search terms. For each case, the type of block, the difficulty of the procedure, the dose of local anaesthetic, positivity of aspiration before and after the event, maternal outcome, Apgar score, onset of symptoms, cardiorespiratory and neurological manifestations, cardiorespiratory support employed, admission to an intensive care unit, cardiac arrest events and duration of mechanical ventilation were extracted.

RESULTS

A total of 605 cases were identified, of which 51 were sufficiently detailed for analysis. Although TSA is described after all neuraxial techniques, spinal after epidural was a particular concern in recent reports. Respiratory distress was universal but apnoea was not. The onset of apnoea was variable, ranging from 1 to 180 min. Hypotension was not invariable and occurred in approximately half of cases. Multiple fatalities and neurological injuries were reported, often in under-resourced areas when providers were not skilled in airway management or when recognition and intervention were delayed. In the most recent reports good outcomes were achieved when effective treatments were rapidly provided.

CONCLUSIONS

The available literature confirms that TSA remains an active clinical problem and that with prompt recognition and treatment good outcomes can be achieved. This requires anticipation and preparedness in all clinical areas where neuraxial techniques are performed.

Causes of Perioperative Cardiac Arrest: Mnemonic, Classification, Monitoring, and Actions

Perioperative cardiac arrest (POCA) is a catastrophic complication that requires immediate recognition and correction of the underlying cause to improve patient outcomes. While the hypoxia, hypovolemia, hydrogen ions (acidosis), hypo-/hyperkalemia, and hypothermia (Hs) and toxins, tamponade (cardiac), tension pneumothorax, thrombosis (pulmonary), and thrombosis (coronary) (Ts) mnemonic is a valuable tool for rapid differential diagnosis, it does not cover all possible causes leading to POCA. To address this limitation, we propose using the preload-contractility-afterload-rate and rhythm (PCARR) construct to categorize POCA, which is comprehensive, systemic, and physiologically logical. We provide evidence for each component in the PCARR construct and emphasize that it complements the Hs and Ts mnemonic rather than replacing it. Furthermore, we discuss the significance of utilizing monitored variables such as electrocardiography, pulse oxygen saturation, end-tidal carbon dioxide, and blood pressure to identify clues to the underlying cause of POCA. To aid in investigating POCA causes, we suggest the Anesthetic care, Surgery, Echocardiography, Relevant Check and History (A-SERCH) list of actions. We recommend combining the Hs and Ts mnemonic, the PCARR construct, monitoring, and the A-SERCH list of actions in a rational manner to investigate POCA causes. These proposals require real-world testing to assess their feasibility.

Cardiac arrest in obstetric patients receiving anaesthetic care: results from the 7th National Audit Project of the Royal College of Anaesthetists

The 7th National Audit Project (NAP7) of the Royal College of Anaesthetists studied peri-operative cardiac arrest. Additional inclusion criteria for obstetric anaesthesia were: cardiac arrest associated with neuraxial block performed by an anaesthetist outside the operating theatre (labour epidural analgesia); and cardiac arrest associated with remifentanil patient-controlled analgesia. There were 28 cases of cardiac arrest in obstetric patients, representing 3% of all cardiac arrests reported to NAP7, giving an incidence of 7.9 per 100,000 (95%CI 5.4-11.4 per 100,000). Obstetric patients were approximately four times less likely to have a cardiac arrest during anaesthesia care than patients having non-obstetric surgery. The single leading cause of peri-operative cardiac arrest in obstetric patients was haemorrhage, with underestimated severity and inadequate early resuscitation being contributory factors. When taken together, anaesthetic causes, high neuraxial block and bradyarrhythmia associated with spinal anaesthesia were the leading causes overall. Two patients had a cardiac arrest related to labour neuraxial analgesia. There were no cardiac arrests related to failed airway management or remifentanil patient-controlled analgesia.

Factors associated with transient bradycardia during local anesthesia administration to the oral cavity under intravenous sedation: A retrospective cohort study

Background/purpose

The possibility of triggering the trigeminocardiac reflex (TCR) during oral surgery is considerably lower than that during other surgeries. A reduced heart rate (HR) of ≥20% from baseline is usually considered a diagnostical criterion for the TCR. Our automated anesthesia charting system often revealed cases of slight transient HR decrease during sedation. We aimed to explore its incidence and associated factors during local anesthesia administration under intravenous sedation.

Materials and methods

This study analyzed the data of 2636 cases that received infiltration anesthesia under intravenous sedation from 2008 to 2010 and had vital signs recorded using an automated anesthesia charting system. Especially, data concerning the average HR before anesthesia and the minimum HR between the initiation and end of anesthesia from anesthetic records were extracted. Moreover, data regarding patients' medical history and unusual reactions during dental treatment were collected. Multivariate logistic regression analysis was performed to identify factors associated with transient bradycardia (TB).

Results

TB occurred in 472 patients (17.9%); no patient developed hypotension or any associated symptoms, suggesting that intravenous sedation was effective in stabilizing vital signs. The factors associated with TB were younger age, gag reflex, and allergy to local anesthetics. There were no differences in sex, patient history, or dose of sedatives between patients with TB and those without TB.

Conclusion

The incidence of TB during infiltration anesthesia under sedation was found to be higher than that previously reported. Additionally, young age and gag reflex were identified as factors associated with bradycardia development.

Bezold-Jarisch Reflex Presenting With Bradypnea, Bradycardia, and Hypotension Following Combined Spinal Epidural Prior to Cesarean Section: A Case Report

The Bezold-Jarisch reflex (BJR) is an inhibitory reflex characterized by bradycardia, hypotension, and apnea originating from ventricular mechanoreceptors. BJR is an uncommon but serious complication of neuraxial anesthesia. We present a case of a 33-year-old female undergoing combined spinal-epidural anesthesia prior to cesarean delivery who developed profound BJR, resulting in emergent actions. Within minutes of injection, she became severely bradycardic (HR: 17 bpm) and hypotensive (SBP: 30s mmHg) with bradypnea (RR: 6/min) and was treated with epinephrine. Fetal bradycardia prompted emergency cesarean section. Following delivery, the patient developed ventricular tachycardia, which was treated with intravenous fluids and cardiac monitoring. Both patient and neonate were discharged in stable condition on postoperative day four. This case illustrates the rapid maternal and fetal compromise associated with BJR during neuraxial anesthesia and the need for prompt recognition and treatment. Key steps include stopping anesthesia, intravenous fluid, left-lateral positioning, judicious vasopressors, fetal monitoring, and preparing for emergent delivery.

Vagal sensory neurons mediate the Bezold-Jarisch reflex and induce syncope

Visceral sensory pathways mediate homeostatic reflexes, the dysfunction of which leads to many neurological disorders1. The Bezold-Jarisch reflex (BJR), first described2,3 in 1867, is a cardioinhibitory reflex that is speculated to be mediated by vagal sensory neurons (VSNs) that also triggers syncope. However, the molecular identity, anatomical organization, physiological characteristics and behavioural influence of cardiac VSNs remain mostly unknown. Here we leveraged single-cell RNA-sequencing data and HYBRiD tissue clearing4 to show that VSNs that express neuropeptide Y receptor Y2 (NPY2R) predominately connect the heart ventricular wall to the area postrema. Optogenetic activation of NPY2R VSNs elicits the classic triad of BJR responses-hypotension, bradycardia and suppressed respiration-and causes an animal to faint. Photostimulation during high-resolution echocardiography and laser Doppler flowmetry with behavioural observation revealed a range of phenotypes reflected in clinical syncope, including reduced cardiac output, cerebral hypoperfusion, pupil dilation and eye-roll. Large-scale Neuropixels brain recordings and machine-learning-based modelling showed that this manipulation causes the suppression of activity across a large distributed neuronal population that is not explained by changes in spontaneous behavioural movements. Additionally, bidirectional manipulation of the periventricular zone had a push-pull effect, with inhibition leading to longer syncope periods and activation inducing arousal. Finally, ablating NPY2R VSNs specifically abolished the BJR. Combined, these results demonstrate a genetically defined cardiac reflex that recapitulates characteristics of human syncope at physiological, behavioural and neural network levels.

Selective anatomical catheter ablation of left atrial ganglionated plexus for vasovagal syncope: Left superior and right anterior ganglionated plexus ablation

BACKGROUND

Vasovagal syncope (VVS) is one of the most common causes of syncope. Traditional treatment has not achieved satisfactory results. The purpose of this study was to assess the feasibility and efficacy of selective anatomical catheter ablation of left atrial ganglionated plexus (GP) as a therapeutic strategy for the patients of symptomatic VVS.

METHODS

A total of 70 patients with at least once recurrent syncopal episode of VVS with a positive head-up tilt test were enrolled. They were divided into GP ablation group and control group. Patients in GP ablation group received anatomical catheter ablation of left superior ganglionated plexus (LSGP) and right anterior ganglionated plexus (RAGP). Patients in the control group were guideline-directed conventional therapy. The primary endpoint was VVS recurrences. The secondary endpoint was the recurrence of syncope and prodrome events.

RESULTS

There were no statistical differences in clinical characteristics between the ablation group (n = 35) and the control group (n = 35). Over a follow-up of 12 months, the ablation group had significantly lower syncope recurrence compared with the control group (5.7% vs. 25.7%, p = .02), and the ablation group had significantly lower syncope and prodrome recurrence compared with the control group (11.4% vs. 51.4%, p < .001). In GP ablation, 88.6% of the patients showed significant vagal response during LSGP ablation, and 88.6% of the patients showed significantly increased heart rate during RAGP ablation.

CONCLUSIONS

For patients with recurrent VVS, selective anatomical catheter ablation of LSGP and RAGP is superior to conventional therapy in reducing syncope recurrence.

C-fos expression in the solitary nucleus medial region and reaction to acute hemorrhage in streptozotocin-stimulated diabetic rats

Examination of circulatory dynamics and autonomic nerve activity in acute hemorrhage in diabetic (DM) rats revealed that despite decreased receptor sensitivity to arterial blood pressure, the DM rats experienced a decline in the heart rate and acceleration of the parasympathetic nerve activity at the sympathoinhibitory phase in response to bleeding (Bezold-Jarisch [B-J] reflex). To elucidate the involvement of the B-J reflex as a reaction to acute hemorrhage in DM rats by assessing c-Fos-positive cell (c-Fos) expression in the nucleus of the solitary tract (SolM), the primary relay nucleus of the baroreflex, Streptozotocin-induced DM and non-DM rats underwent controlled-graded bleeding or continuous phenylephrine infusion under conscious state. Changes in hemodynamics and autonomous nervous system caused by acute hemorrhage and continuous phenylephrine infusion were examined by analyzing blood pressure-heart rate variability. Furthermore, effects of hemorrhage and phenylephrine infusion on the expression of c-Fos in SolM were examined. DM rats showed increased c-Fos expression in response to acute blood loss in the SolM. Non-DM rats showed the same phenomenon in response to continuous phenylephrine infusion in the SolM. Significant interactions between DM and Non-DM rats were observed among hemodynamic and autonomic response to acute hemorrhage and continuous phenylephrine infusion. DM rats were sensitive to acute blood loss, and the circulatory system easily collapsed with accelerating parasympathetic activity in the form of the B-J reflex.

The effect of intravenous granisetron on prophylactic ephedrine for preventing hypotension after general anaesthesia induction in elderly patients: a randomized controlled trial

Serotonin 3 receptor antagonists, a commonly used drug for preventing postoperative nausea and vomiting, have recently been reported to decrease the incidence of hypotension and the need for vasoactive drugs after spinal anaesthesia in obstetric surgery. However, it remains unknown whether they could also prevent hypotension after induction of general anaesthesia. In the current study, we aimed to investigate the effect of intravenous granisetron on prophylactic ephedrine for preventing hypotension after general anaesthesia induction in elderly patients. Sixty elderly patients were randomly assigned to receive granisetron or saline control 30 min before induction of general anaesthesia. The first patient in each group received a prophylactic dose of ephedrine (0.15 mg kg^-1) to prevent hypotension. The prophylactic dose for each patient was increased or decreased by 0.05 mg/kg based on the efficacy results of the previous patient. The up-down sequential allocation analysis and probit regression was used to calculate the effective dose for 50% of patients (ED50) with prophylactic ephedrine. In the up-down sequential allocation analysis, the ED50 of ephedrine was significantly lower in group granisetron (0.08 mg kg^-1 [95% CI, 0.06-0.11 mg kg^-1]) when compared with group control (0.14 mg kg^-1 [95% CI, 0.13-0.16 mg kg^-1]) (P < 0.001). The conclusion was further supported by probit regression analysis (0.09 mg kg^-1 [95% CI, 0.05-0.12 mg kg^-1] in group granisetron and 0.14 mg kg^-1 [95% CI, 0.12-0.16 mg kg^-1] in group control). Intravenous granisetron reduced the requirement of prophylactic ephedrine in preventing hypotension after general anaesthesia induction in elderly patients.

Negative Chronotropic Cardiovascular Changes in Lumbar Spine Surgery: A Potential Spinal-Cardiac Reflex?

Cardiovascular changes following lumbar spine surgery in a prone position are exceedingly rare. Over the past 20 years, a total of six cases have been published where patients experienced varying degrees of bradycardia, hypotension, and asystole, which could be attributed to intraoperative dural manipulation. As such, there is emerging evidence for a potential neural-mediated spinal-cardiac reflex. The authors report their experience of negative chronotropy during an elective lumbar spine surgery that coincided with dural manipulation and review the available literature. A 34-year-old male presented with a long-standing history of lower back pain recently deteriorating to bilaterally radiating leg pain, with restricted left leg raise, and numbness at the left L5 dermatomal territory. The patient was an athletic police officer with no comorbidities or past medical history. Magnetic resonance imaging lumbosacral spine revealed spinal stenosis most pronounced at L4/L5 and disc bulges at L3/L4 and L5/S1. The patient opted for lumbar decompression surgery. After an unremarkable comprehensive preoperative workup, including cardiac evaluation (electrocardiogram, echocardiogram), the patient was induced general anesthesia in a prone position. A lumbar incision was made from L2 to S1. When the left L4 nerve root was retracted while removing the prolapsed disc at L4/L5, the anesthetist cautioned the surgeon of bradycardia (34 beats per minute [bpm]), and the surgery was immediately stopped. The heart rate improved to 60 bpm within 30 seconds. When the root was later retracted again, a second episode of bradycardia occurred for 4 minutes with heart rate declining to 48 bpm. The surgery was stopped, and after 4 minutes, the anesthetist administered 600 µg of atropine. The heart rate then rose to 73 bpm within 1 minute. Other potential causes for bradycardia were excluded. The total blood loss was estimated to be 100 mL. He remains well at his 6-month follow-up and has returned to work as normal. Akin to previously published cases, each episode of bradycardia coincided with dural manipulation, which may indicate a possible reflex between the spinal dura mater and the cardiovascular system. Such a rare adverse event may occur even in seemingly healthy, young individuals, and anesthetists should caution the operating surgeon of bradycardias to exclude operative manipulation of the dura as the cause. While this phenomenon is only reported in a handful of lumbar spine surgery cases, it provides evidence for a potential spinal-cardiac physiological reflex in the lumbar spine that may be neural mediated and should be investigated further.

An integrated strategy to explore the potential role of melatonin against copper-induced adrenaline toxicity in rat cardiomyocytes: Insights into oxidative stress, inflammation, and apoptosis

AIMS

Circumstantial anxiety as well as chronic stress may stimulate the release of stress hormones including catecholamines. Adrenaline toxicity has been implicated in many cardiovascular conditions. Considering previous literature that suggests the oxidative potential of the adrenaline-copper entity, we have investigated its potential nocuous role in isolated adult rat cardiomyocytes, the underlying molecular mechanism, and its possible protection by melatonin.

MAIN METHODS

Given the mechanistic congruity of adrenaline-copper (AC) with the well-established H₂O₂-copper-ascorbate (HCA) system of free radical generation, we have used the latter as a representative model to study the cytotoxic nature of AC. We further investigated the cardioprotective efficacy of melatonin in both the stress models through scanning electron microscopy, immunofluorescence, flow cytometry, and western blot analysis.

KEY FINDINGS

Results show that melatonin significantly protects AC-treated cardiomyocytes from ROS-mediated membrane damage, disruption of mitochondrial membrane potential, antioxidant imbalance, and distortion of cellular morphology. Melatonin protects cardiomyocytes from inflammation by downregulating pro-inflammatory mediators viz., COX-2, NF-κB, TNF-α, and upregulating anti-inflammatory IL-10. Melatonin significantly ameliorated cardiomyocyte apoptosis in AC and HCA-treated cells as evidenced by decreased BAX/BCL-2 ratio and subsequent suppression of caspase-9 and caspase-3 levels. The isothermal calorimetric study revealed that melatonin inhibits the binding of adrenaline bitartrate with copper in solution, which fairly explains the rescue potential of melatonin against AC-mediated toxicity in cardiomyocytes.

SIGNIFICANCE

Findings suggest that the multipronged strategy of melatonin that includes its antioxidant, anti-inflammatory, anti-apoptotic, and overall cardioprotective ability may substantiate its potential therapeutic efficacy against adrenaline-copper-induced damage and death of adult rat cardiomyocytes.

Transient asystole associated with vasovagal reflex in an oral surgery patient: A case report

The perioperative cardiac events may be brought about by a relative imbalance of autonomic activities due to excessive psychological and physical stress. The present case study focuses on the asystole that can occur as a serious cardiac adverse event associated with vasovagal reflex likely to be triggered by venipuncture for securing an intravenous line during dental care. In addition, we describe and discuss herein the management of intravenous sedation for a dental phobic patient who experienced the vasovagal reflex involved in an unexpected transient asystole. The patient with vasovagal reflex episodes in daily life, who had no past medical history relevant to cardiovascular disorders, was scheduled for dental extraction under intravenous sedation. Immediately after peripheral intravenous catheterization, she complained of discomfort and nausea, and a II-lead electrocardiogram revealed asystole following bradycardia associated with vasovagal reflex. Oxygenation and intravenous fluid loading in the supine position with elevation of the lower extremities restored sinus rhythm and normal hemodynamics without the intervention of cardiopulmonary resuscitation. With administration of intravenous atropine and betamethasone as premedication, she was uneventfully treated in stress-free psychosomatic conditions under optimal sedation with midazolam without any signs of cardiovascular disorders. After administration of flumazenil, the patient satisfactorily recovered from sedation without re-sedation. The present case suggests that an asystole associated with vasovagal reflex can be triggered by venipuncture for intravenous catheterization during dental anxiety likely to affect the imbalance between sympathetic and parasympathetic activities.

Ondansetron Reduces the Incidence of Hypotension after Spinal Anaesthesia: A Systematic Review and Meta-Analysis

Hypotension induced by spinal anaesthesia is a common clinical complication associated with multiple perioperative adverse events. We conducted a systemic review and meta-analysis to confirm whether ondansetron could alleviate hypotension following spinal anaesthesia. PubMed, Embase, Web of Science, and Cochrane Library were searched to identify eligible randomised controlled trials from their respective database inception dates to 30 September 2022. The primary outcome of the meta-analysis was the incidence of hypotension after spinal anaesthesia. The risk of bias in the included studies was evaluated using the revised Cochrane risk of bias tool for randomised trials (RoB 2.0). Grading of Recommendations, Assessment, Development, and Evaluation was applied to assess the level of certainty. A total of 25 studies were included in this research. The meta-analysis revealed that ondansetron significantly decreased the incidence of hypotension (RR = 0.65, 95% CI 0.53−0.80, p < 0.01, I2 = 64%) and bradycardia. In addition, patients treated with ondansetron had a reduced need for vasopressors administration. This study suggests that ondansetron may be recommended as a prophylaxis for hypotension and bradycardia following spinal anaesthesia; the level of evidence was moderate with a high level of heterogeneity.

Efficacy of Variable Doses of Prophylactic Intravenous Ondansetron in Attenuating Spinal Induced Hypotension in Parturients Undergoing Caesarean Delivery: A Randomised Control Trial

Introduction

Spinal anaesthesia is frequently associated with adverse effects like maternal hypotension and bradycardia. This effect is due to a decrease in systemic vascular resistance, a decrease in central venous pressure or Bezold-Jarisch Reflex (mediated by 5-HT3 receptors). We aimed to measure the effect of three different doses of prophylactic intravenous ondansetron (5-HT3 antagonists) with a placebo on maternal haemodynamics.

Methods

A prospective randomised control study was done over 240 parturients, aged 19-35 years. They were randomly allocated into four groups (n=60) Group O4, Group O6, Group O8 and Group S to receive either intravenous ondansetron 4 mg, 6 mg, 8 mg or 0.9% normal saline respectively. Haemodynamic variables (systolic blood pressure [SBP], diastolic blood pressure [DBP], mean arterial pressure [MAP], heart rate [HR]) were recorded at 2-minute intervals for the first 20 minutes and at 5-minute intervals for further 30 minutes.

Results

A significant decrease in haemodynamic parameters was observed in group S when compared with ondansetron groups at various time intervals (p<0.05). The difference was most significant in groups O6 and O8. Development of nausea and vomiting was significantly higher in Group S compared to ondansetron groups (p< 0.005). The requirement for ephedrine was more in Group S in comparison to ondansetron groups (p<0.0001).

Conclusion

All three groups of ondansetron showed a decrease in the incidence of hypotension and use of vasopressor but Group O6 and O8 were more effective in attenuating spinal-induced hypotension in parturients undergoing caesarean section.

Veno-Arterial Extracorporeal Membrane Oxygenation Rescue in a Patient With Pulmonary Hypertension Presenting for Revision Total Hip Arthroplasty: A Case Report and Narrative Review

Patients with pulmonary hypertension (PH) are at an increased risk of perioperative morbidity and mortality when undergoing non-cardiac surgery. We present a case of a 57-year-old patient with severe PH, who developed cardiac arrest as the result of right heart failure, undergoing a revision total hip arthroplasty under combined spinal epidural anesthesia. Emergent veno-arterial (VA) extracorporeal membrane oxygenation (ECMO) was undertaken as rescue therapy during the pulmonary hypertensive crisis and a temporizing measure to provide circulatory support in an intensive care unit (ICU). We present a narrative review on perioperative management for patients with PH undergoing non-cardiac surgery. The review goes through the updated hemodynamic definition, clinical classification of PH, perioperative morbidity, and mortality associated with PH in non-cardiac surgery. Pre-operative assessment evaluates the type of surgery, the severity of PH, and comorbidities. General anesthesia (GA) is discussed in detail for patients with PH regarding the benefits of and unsubstantiated arguments against GA in non-cardiac surgery. The literature on risks and benefits of regional anesthesia (RA) in terms of neuraxial, deep plexus, and peripheral nerve block with or without sedation in patients with PH undergoing non-cardiac surgery is reviewed. The choice of anesthesia technique depends on the type of surgery, right ventricle (RV) function, pulmonary artery (PA) pressure, and comorbidities. Given the differences in pathophysiology and mechanical circulatory support (MCS) between the RV and left ventricle (LV), the indications, goals, and contraindications of VA-ECMO as a rescue in cardiopulmonary arrest and pulmonary hypertensive crisis in patients with PH are discussed. Given the significant morbidity and mortality associated with PH, multidisciplinary teams including anesthesiologists, surgeons, cardiologists, pulmonologists, and psychological and social worker support should provide perioperative management.

Asystole following spinal anaesthesia: the hazards of intrinsic cardiac reflexes

Unwanted initiation of intrinsic cardiac reflexes can precipitate bradycardia and cardiac arrest after spinal anaesthesia. We report the case of a 40-year-old man who suffered sudden asystolic cardiac arrest following spinal anaesthesia prior to planned abdominal surgery, likely due to the initiation of one or more intrinsic cardiac reflexes including the Bezold-Jarisch reflex, the reverse Bainbridge reflex and the pacemaker stretch reflex. The characteristics of this patient placed him at increased risk of this underappreciated cause of bradycardia and hypotension. We present a summary of the physiology and clinical features relevant to this case and the considerations for avoidance of similar complications after spinal anaesthesia.

Dysautonomia following breast surgery: Disproportionate response to post-operative hematoma

Background

Up to 10% of patients undergoing breast surgery suffer from bleeding complications. Some experience severe hypotension and bradycardia of unclear etiology. Similar to the vasovagal hyperstimulation provoked by abdominal insufflation during laparoscopic surgery, we hypothesize that chest wall stretch from postoperative breast hematoma may mechanically stretch the vagus nerve, triggering dysautonomia disproportionate to the degree of blood loss.

Methods

A single-institution retrospective review of patients requiring reoperation for hematoma evacuation following breast surgery between 2011 and 2021 was performed. The relationship between hematoma volume and hemodynamic instability, as well as hematoma volume and vasovagal symptoms, was measured.

Results

Sixteen patients were identified. Average hematoma volume was 353 mL, and average minimum mean arterial pressure was 64 mm Hg (range: 34–102 mm Hg). Fifty-six percent of patients reported symptoms including dizziness, somnolence, and/or syncope. Accounting for body surface area, patients with larger hematomas had similar minimum mean arterial pressures compared to those with smaller hematomas, 55 and 73 mm Hg, respectively (P = .0943). However, patients in the large hematoma group experienced over 3 times as many vasovagal symptoms, 88% and 25%, respectively (P = .0095).

Conclusion

Patients with large hematomas reported significantly more vagal symptoms compared to those with small hematomas despite similar mean arterial pressures. In addition, the trend of lower mean arterial pressures and heart rates more closely resembles vagal hyperstimulation than hypovolemic shock. Early hematoma evacuation to relieve vagal nerve stretch and parasympatholytics to reverse dysautonomia are targeted interventions to consider in this patient population rather than fluids, vasopressors, and blood products that are used in cases of hemodynamic instability due to hypovolemia alone.

Yoga as a treatment for vasovagal syncope: A systematic review and meta-analysis

BACKGROUND

Yoga therapy is being used for vasovagal syncope (VVS). However, there is no sufficient evidence. We aimed to evaluate the effect of yoga as an adjunct to the standard therapy on patients with recurrent VVS.

METHODS

Electronic databases were systematically searched to collect studies assessing the clinical effects of yoga along with guideline-directed treatment in patients with recurrent VVS. The outcomes were the number of VVS attacks and quality of life (QoL) assessment by Syncope Functional Status Questionnaire (SFSQ) scores at 12 months. We used the Mantel- Haenszel random-effects model to calculate the mean difference (MD) and 95% confidence interval (CI). We used The Cochrane Collaboration Risk of Bias Tool and Newcastle-Ottawa Scale for risk of bias assessment.

RESULTS

Four studies were included, two RCTs and two observational studies. The total of participants was 309, with a mean age of 36.4 ± 13.5 years. The male participants represented 141 (45.6%) being males. The baseline syncope burden was 3.5 ± 2.38 episodes over 15.6 ± 12.8 months. Yoga therapy significantly reduced the number of episodes of syncope and presyncope compared to the control group (MD -1.86; 95% CI -3.30, -0.43; P = 0.01). Nevertheless, yoga therapy did not show significant improvement in the QoL assessed by SFSQ scores (MD -30.69; 95% CI -62.22,0.83; P = 0.06).

CONCLUSION

Yoga therapy is a useful lifestyle intervention that can reduce the frequency of syncope and presyncope among patients with recurrent VVS. However, higher-quality RCTs are needed to confirm our results.

Postoperative vasovagal cardiac arrest after spinal anesthesia for lumbar spine surgery

Background:

Spinal anesthesia is being increasingly recognized as a favorable alternative to general anesthesia. However, there are still several considerations for its safe and effective use.

Case Description:

A 62-year-old male received spinal anesthesia during an uneventful L3-L5 decompressive laminectomy. However, he subsequently experienced a brief episode of pulseless electrical activity in the post-anesthesia care unit, and was successfully resuscitated without further sequelae. This was attributed to a vasovagal episode, with his notable prior history of experiencing vasovagal syncope with lightheadedness and fainting at the sight of blood.

Conclusion:

Patients with a history of vasovagal syncope may be predisposed to experiencing brief potentiated episodes of severe bradycardia and even cardiac arrest following spinal anesthesia.

Unusual presentation of supraventricular tachycardia degenerating into ventricular fibrillation during pregnancy: Aortocaval compression the probable culprit

Cardiac arrhythmias are common and often benign in pregnancy. However, haemodynamic instability can occur when tachyarrhythmias are accompanied by aortocaval compression, which can lead to loss of cardiac output. We present an atypical case of a pregnant woman with a supraventricular tachyarrhythmia, which degenerated into ventricular fibrillation arrest while supine due to aortocaval compression. Inducible atypical atrioventricular nodal re-entry tachycardia was subsequently detected on electrophysiological study and presumed to be the most likely initial supraventricular tachyarrhythmia.

Sympathetic Nerve Activity and Baroreflex are Strongly Altered in a Context of Severe Hypertension Using the Spontaneously Hypertensive Rat Model Associated with Chronic Reduction of Nitric Oxide

The aim of our study is to investigate the sympathetic output and baroreflex via renal sympathetic nerve activity (RSNA) recording in a model of severe hypertension which exhibits arterial, cardiac, and renal damages, the spontaneously hypertensive rat (SHR) under lowered NO bioavailability. SHR are treated from 18 to 20 weeks of age with a low dose of L-NAME, a NO synthase inhibitor, in drinking water (SHRLN) and compared to SHR and normotensive Wistar Kyoto (WKY) rats. After the two-week treatment, rats are anesthetized for RSNA, mean blood pressure (MBP), and heart rate (HR) recording. MBP is higher in SHR than in WKY and higher in SHRLN than in SHR. Compared to WKY, SHR displays an alteration in the baroreflex with a displacement of the sympathoinhibition curve to highest pressures; this displacement is greater in SHRLN rats. The bradycardic response is reduced in SHRLN compared to both SHR and WKY. In hypertensive rats, SHR and SHRLN, basal RSNA is modified, the maximal amplitude of burst is reduced, but minimal values are increased, indicating an increased basal RSNA with reduced bursting activity. The temporal correlation between RSNA and HR is preserved in SHR but altered in 10 SHRLN out of 10. The RSNA inhibition triggered by the Bezold–Jarisch reflex activation is not modified in hypertensive rats, SHR or SHRLN, in contrast to that triggered by the baroreflex. Histological analysis of the carotid bifurcation does not reveal any abnormality in SHRLN at the level of the carotid sinus. In conclusion, data indicate that the sympathetic outflow is altered in SHRLN with a strong reduction of the baroreflex sympathoinhibition and suggest that its central pathway is not involved. These additional results on SHRLN also confirm the usefulness of this model of severe hypertension with multiple target organ damages.

Comparison between mephentermine and ondansetron for the prevention of post spinal hypotension: a prospective randomized trial

Background and Aims: Spinal anesthesia is a technique often associated with side effects like hypotension and bradycardia. Recent studies have shown that the use of ondansetron leads to a decreased incidence of hypotension induced by spinal anesthesia. This prospective, randomized, controlled, double-blind study was done to compare the efficacy of the prophylactic use of intravenous (IV) ondansetron and mephentermine on post-spinal hypotension. Methods: A total of 130 patients were randomly allocated to one of two groups: Group O received 4 mg IV ondansetron and Group M received 6 mg of IV mephentermine. All patients received spinal anesthesia using 3 mL of 0.5% hyperbaric bupivacaine. Assessment of blood pressure and heart rate (HR) was done for 30 minutes after spinal anesthesia was performed. Quantitative data were analyzed using ANOVA tests and qualitative data were analyzed using the Chi-square tests. Results: Both groups were comparable regarding demographic data. Mean arterial blood pressure (MAP) in Group O was lower than Group M at 5 to 25 minutes and difference of MAP between the two groups was > 20% of baseline values (p < 0.05). HR was comparable between groups. No statistically significant differences were seen in side effects between the two groups. Conclusion: Our study shows that the preemptive use of both ondansetron and mephentermine significantly decreases the incidence of post-spinal hypotension.

Granisetron or ondansentron to prevent hypotension after spinal anesthesia for elective cesarean delivery: A randomized placebo-controlled trial

STUDY OBJECTIVE

This study aimed to compare the effects of high doses of ondansetron and granisetron before spinal anesthesia on hemodynamic parameters in patients undergoing elective cesarean section.

DESIGN

A double-blinded randomized placebo-controlled trial.

SETTING

Operating room.

PATIENTS

A total of 120 parturients with term pregnancy undergoing elective cesarean section with combined spinal-epidural anesthesia were included.

INTERVENTIONS

Three groups (n = 40 for each group) were formed by randomization. Five minutes before the anesthesia procedure, Group I received 8 mg intravenous (IV) ondansetron diluted in 10 ml normal saline, Group II received IV 3 mg granisetron diluted in 10 ml normal saline, and Group III received IV 10 ml normal saline.

MEASUREMENTS

Following intrathecal drug administration, intraoperative hemodynamic changes were recorded every 2 min for 20 min and then every 5 min until the end of the operation.

MAIN RESULTS

Twenty patients (50%) in Group I, 12 patients (30%) in Group II, and 29 patients (72.5%) in Group III had hypotension requiring treatment with IV ephedrine (P = 0.001). The ephedrine requirement in Group III was significantly higher than in Groups I (P = 0.033) and II (P < 0.001). Also, the ephedrine requirement in Group II was lower than in Group I, but the difference was not statistically significant (P = 0.055). The mean arterial pressure for the three groups differed in the 10th, 18th, and 60th minutes. The number of patients with nausea or vomiting was lower in Groups I and II than in Group III (P < 0.001). At 5 min, the Apgar scores were higher than 8 for all neonates. Postoperative scores for the visual analogue scale were similar for all groups.

CONCLUSIONS

It was concluded that prophylactic IV administration of 3 mg of granisetron or 8 mg of ondansetron before spinal anesthesia results in a significantly lower ephedrine requirement compared to placebo.

Risk factor for vital signs elevation during percutaneous microwave ablation of liver tumor under deep sedation

PURPOSE

To evaluate the frequency and the degree of vital signs elevation, as well as to elucidate the risk factors for elevation of cardiopulmonary parameters.

MATERIALS AND METHODS

We retrospectively evaluated the medical records of 101 patients who received microwave ablation (MWA) under deep sedation with propofol. Univariate analysis followed by multivariate linear regression analysis was performed to determine the risk factors associated with the elevation of cardiopulmonary parameters.

RESULTS

The heart rate (HR), mean blood pressure (BP) and respiratory rate (RR) were elevated in 53.5%, 45.5% and 30.7%. Hyperhemodynamic state (mean BP or HR increased > 30% of the baseline) and high RR (RR > 20 times/min) were detected in 23.8% and 13.9%. Age ≤ 50 years was signifiant for mean BP and HR elevation (p = 0.032; p = 0.027), ablation zone abutting the parietal peritoneum (p = 0.001; p = 0.001; p < 0.001) and the diaphragm (p = 0.001) were risk factors for BP and RR elevation.

CONCLUSIONS

Elevations in HR and BP are common. Risk factors for vital signs elevation include ablation zone abutting the parietal peritoneum and the diaphragm, as well as young age. These findings help devise strategies for anesthetic management.

Blood pressure and cardiac output during caesarean delivery under spinal anaesthesia: a prospective cohort study

OBJECTIVES

We have previously established a method to measure transfer of nutrients between mother, placenta and fetus in vivo. The method includes measurements of maternal and fetal blood flow by Doppler ultrasound prior to spinal anaesthesia. Spinal anaesthesia affects maternal blood pressure and cardiac output. We aimed to determine the effect of spinal anaesthesia in mothers undergoing an elective caesarean section on blood pressure, heart rate and cardiac output, and whether cardiac output levels were comparable before induction of spinal anaesthesia and before delivery.

DESIGN

Prospective cohort study.

SETTING

Tertiary hospital in Norway.

PARTICIPANTS

76 healthy women with uneventful pregnancies undergoing an elective caesarean section.

INTERVENTIONS

We induced spinal anaesthesia with a standard prevention of hypotension including intravenous fluid coloading and phenylephrine infusion.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome measure was maternal cardiac output, and secondary outcome measures were invasive systolic blood pressure and heart rate. We measured heart rate and blood pressure by continuous invasive monitoring with a cannula in the radial artery. Cardiac output was estimated based on continuous arterial waveform. We compared maternal parameters 30 s before induction of spinal anaesthesia to 30 s before delivery.

RESULTS

Median age at delivery was 34.5 (range 21-43) years and 17 of 76 women were nulliparous. The most prevalent indications were previous caesarean section and maternal request. Among 76 included women, 71 had sufficient data for analysis of endpoints. Median cardiac output was 6.51 (IQR (5.56-7.54) L/min before spinal anaesthesia and 6.40 (5.83-7.56) L/min before delivery (p=0.40)). Median invasive systolic blood pressure increased from 128.5 (120.1-142.7) mm Hg to 134.1 (124.0-146.6) mm Hg (p=0.014), and mean heart rate decreased from 86.0 (SD 13.9) to 75.2 (14.2) (p<0.001).

CONCLUSIONS

Maternal cardiac output at the time of caesarean delivery is comparable to levels before induction of spinal anaesthesia.

TRIAL REGISTRATION NUMBER

NCT00977769.

Relationship Between Intraoperative and Preoperative Ambulatory Nighttime Heart Rates: A Secondary Analysis of a Prospective Observational Study

BACKGROUND

It remains unknown what constitutes physiologically relevant intraoperative bradycardia. Intraoperative bradycardia is usually defined using absolute heart rate thresholds, ignoring preoperative baseline heart rates. In contrast, we considered defining intraoperative bradycardia relative to preoperative ambulatory nighttime heart rate. Specifically, we hypothesized that the individual mean intraoperative heart rate is lower than the mean preoperative ambulatory nighttime heart rate. We, therefore, sought to investigate the relationship between the intraoperative and preoperative ambulatory nighttime heart rates in adults having noncardiac surgery with general anesthesia. Additionally, we sought to investigate the incidence of intraoperative bradycardia using relative versus absolute heart rate thresholds.

METHODS

We conducted a secondary analysis of a database from a prospective study including preoperative ambulatory and intraoperative heart rates in 363 patients having noncardiac surgery with general anesthesia.

RESULTS

The mean intraoperative heart rate was lower than the mean nighttime heart rate (mean difference, -9 bpm; 95% confidence interval [CI], -10 to -8 bpm; P < .001). The mean intraoperative heart rate was lower than the mean nighttime heart rate in 319 of 363 patients (88%; 95% CI, 84%-91%). The incidence of intraoperative bradycardia was 42% (95% CI, 38%-47%) when it was defined as intraoperative heart rate >30% lower than mean nighttime heart rate and 43% (95% CI, 38%-49%) when it was defined as intraoperative heart rate <45 bpm.

CONCLUSIONS

The mean intraoperative heart rate is lower than the mean nighttime heart rate in about 9 of 10 patients. Intraoperative bradycardia might thus be physiologically and clinically important. Future research needs to investigate whether there is an association between intraoperative bradycardia and postoperative outcomes.

Effect of ondansetron on spinal anesthesia-induced hypotension in non-obstetric surgeries: a randomised, double-blind and placebo-controlled trial

BACKGROUND AND OBJECTIVES

Spinal anesthesia is an effective technique for many surgical procedures, but it is often associated with an increased risk of potentially deleterious hemodynamic disturbances. The benefits of prophylactic ondansetron for preventing spinal anesthesia-induced hypotension are still uncertain. Therefore, this study aimed to compare the effect of ondansetron and placebo before spinal block on the incidence of hypotension in patients having non-obstetric surgeries.

METHODS

Randomized, double-blind, parallel-group, superiority trial with a 1:1 allocation ratio. A total of 144 patients scheduled for non-obstetric surgeries with an indication for spinal anesthesia were randomized. Patients received intravenous ondansetron (8mg) or placebo before standard spinal anesthesia. The primary outcome was the rate of hypotension in the first 30 minutes after spinal anesthesia.

RESULTS

Hypotension occurred in 20 of 72 patients (27.8%) in the ondansetron group and in 36 of 72 patients (50%) in the placebo group (Odds Ratio-OR=0.38; 95% Confidence Interval-CI 0.19 to 0.77; p=0.007). Fewer patients in the ondansetron group required ephedrine compared to the placebo group (13.9% vs. 27.8%; OR=0.42; 95% CI 0.18 to 0.98; p=0.04). Exploratory analyses revealed that ondansetron may be more effective than placebo in patients aged 60 years or older (OR=0.12; 95% CI 0.03 to 0.48; p=0.03). No difference in heart rate variations was observed.

CONCLUSION

Our findings suggest that ondansetron can be a viable and effective strategy to reduce both the incidence of spinal anesthesia-induced hypotension and vasopressors usage in non-obstetric surgeries.

BEZOLD JARISCH REFLEX DURING HALO-GRAVITY TRACTION: CASE REPORT

ABSTRACT Halo-gravity traction is an option that can be used in the treatment of severe spinal deformities. The author reports a complication not yet described in the literature in which rapid correction of the deformity triggered the Bezold Jarisch reflex. Level of evidence IV; Case Series.

Perioperative management of patients with pulmonary hypertension undergoing non-cardiothoracic, non-obstetric surgery: a systematic review and expert consensus statement

BACKGROUND

The risk of complications, including death, is substantially increased in patients with pulmonary hypertension (PH) undergoing anaesthesia for surgical procedures, especially in those with pulmonary arterial hypertension (PAH) and chronic thromboembolic PH (CTEPH). Sedation also poses a risk to patients with PH. Physiological changes including tachycardia, hypotension, fluid shifts, and an increase in pulmonary vascular resistance (PH crisis) can precipitate acute right ventricular decompensation and death.

METHODS

A systematic literature review was performed of studies in patients with PH undergoing non-cardiac and non-obstetric surgery. The management of patients with PH requiring sedation for endoscopy was also reviewed. Using a framework of relevant clinical questions, we review the available evidence guiding operative risk, risk assessment, preoperative optimisation, and perioperative management, and identifying areas for future research.

RESULTS

Reported 30 day mortality after non-cardiac and non-obstetric surgery ranges between 2% and 18% in patients with PH undergoing elective procedures, and increases to 15-50% for emergency surgery, with complications and death usually relating to acute right ventricular failure. Risk factors for mortality include procedure-specific and patient-related factors, especially markers of PH severity (e.g. pulmonary haemodynamics, poor exercise performance, and right ventricular dysfunction). Most studies highlight the importance of individualised preoperative risk assessment and optimisation and advanced perioperative planning.

CONCLUSIONS

With an increasing number of patients requiring surgery in specialist and non-specialist PH centres, a systematic, evidence-based, multidisciplinary approach is required to minimise complications. Adequate risk stratification and a tailored-individualised perioperative plan is paramount.

Territorial and Extraterritorial Trigeminocardiac Reflex: A Review for the Neurosurgeon and a Type IV Reflex Vignette

The trigeminocardiac reflex (TCR) is a complex and, sometimes, fatal event triggered by overstimulation of the trigeminal nerve (TN) and its territorial and spinal cord branches. We reviewed and compiled for the neurosurgeon key aspects of the TCR that include a novel and straightforward classification, as well as morphophysiology, pathophysiology, neuromonitoring and neuromodulation features. Further, we present intraoperative data from a patient who developed extraterritorial, or type IV, TCR while undergoing a cervical surgery. TCR complexity, severity and unwanted outcomes indicate that this event should not be underestimated or overlooked in the surgical room. Timely TCR recognition in surgical settings is valuable for applying effective intraoperative management to prevent catastrophic outcomes.

Hemodynamically significant cardiac arrhythmias during general anesthesia for spine surgery: A case series and literature review

•

Although multiple factors have been implicated, our case series highlights SSEP stimulation as a common etiology of arrhythmia.

•

Significant bradycardia and CA during spine surgery does not always require termination of the surgical procedure.

•

Decision making should be undertaken in each case individually based on patient condition and circumstances of each event.

•

Surgeons and anesthesiologists should be aware of and prepared to treat significant cardiac arrhythmias during spine surgery even in otherwise healthy patients without known risk factors.

Background context

Hemodynamically significant bradycardia and cardiac arrest (CA) are rare under general anesthesia (GA) for spine surgery. Although patient risks are well defined, emerging data implicate surgical, anesthetic and neurologic factors which should be considered in the immediate management and decision to continue or terminate surgery.

Purpose

To characterize causes and contributors to significant arrhythmias during spine surgery. We also provide an updated literature review to inform spine care teams and aid in the management of intraoperative bradycardia and CA.

Study design

Case series and literature review

Patient sample

Six patients who underwent spine surgery from 03/2016 to 01/2020 at a single institution and developed unexpected hemodynamically significant arrhythmia

Outcome measures

Our primary outcome was to identify potential risk factors of interest for significant arrhythmia during spine surgery.

Methods

Medical records of patients who underwent spine surgery from 03/2016 to 01/2020 at a single institution and developed unexpected hemodynamically significant arrhythmia during spine surgery were identified from a departmental Quality Assurance Database. We evaluated the presence/absence of patient, surgical, anesthetic and neurologic risk factors and estimated the most likely etiology of the event, immediate and subsequent management, whether surgery was postponed or continued and outcomes.

Results

We found a temporal relationship of bradyarrhythmia and CA after somatosensory evoked potential (SSEP) stimulation in 4/6 cases and pharmacy/polypharmacy in 2/6. Surgery was completed in 4/6 patients, and terminated in 2/6 (subsequently completed in both). We found no adverse outcomes in any patients. Our literature review predominately identified case reports for guidance to support decision making. New literaure suggests peripheral nerve blocks and opioid-sparing anesthetic agents should also be considered.

Conclusions

Significant bradycardia and CA during spine surgery does not always require termination of the surgical procedure. Decision making should be undertaken in each case individually, with an updated awareness of potential causes. The study also suggests the need for large prospective studies to adequately assess incidence, risk factors and outcomes.

Adverse heart rate responses during beach-chair position for shoulder surgeries - A systematic review and meta-analysis of their incidence, interpretations and associations

Background and Aims

Evaluations of adverse heart rate (HR)-responses and HR-variations during anaesthesia in beach-chair-position (BCP) for shoulder surgeries have not been done earlier. We analysed the incidence, associations, and interpretations of adverse HR-responses in this clinical setting.

Methods

We performed a meta-analysis of trials that reported HR-related data in anaesthetised subjects undergoing elective shoulder surgeries in BCP. Studies included prospective, randomised, quasi-randomised and non-randomised, controlled clinical trials as well as observational cohorts. Literature search was conducted in MEDLINE, EMBASE, CINHAL and the Cochrane Central Register of Controlled Trials of the 21^st century. In the first analysis, we studied the incidence and associations of bradycardia/hypotension-bradycardia episodes (HBE) with respect to the type of anaesthesia and different pharmacological agents. In the second, we evaluated anaesthetic influences, associations and inter-relationships between monitored parameters with respect to HR-behaviours.

Results

Among the trials designed with bradycardia/HBE as a primary end point, the observed incidence of bradycardia was 9.1% and that of HBE, 14.9% and 22.7% [(for Interscalene block (ISB) ± sedation) subjects and general anaesthesia (GA) + ISB, respectively]. There was evidence of higher observed risk of developing adverse HR-responses for GA subjects over ISB (Risk Difference, P < 0.05). Concomitant use of β-agonists did not increase risk of HBEs (P = 0.29, I ²= 11.4%) or with fentanyl (P = 0.45, I ²= 0%) for ISB subjects (subgroup analysis). Fentanyl significantly influenced the HR-drop over time [meta-regression, estimates (standard error), 14.9 (5.4), 9.8 (4.3) and 17 (2.6); P = 0.007, 0.024 and <0.001; for early, mid and delayed periods, respectively] in GA subjects. With respect to number of subjects experiencing cerebral desaturation events (CDEs), total intravenous anaesthesia (TIVA)- propofol had higher risk over inhalational anaesthesia (P = 0.006, I ² = 86.7%). Meta-correlation analysis showed relationships between the HR and rSO₂(regional cerebral oxygen saturation) or SjvO₂(jugular venous oxygen saturation) values (r = 0.608, 95%CI, 0.439 to 0.735, P < 0.001, I ²= 77.4% and r = 0.397, 95%CI, 0.151 to 0.597, P < 0.001, I ²= 64.3%, respectively).

Conclusions

There is not enough evidence to claim the associations of adverse HR-responses with any specific factor. HR-fall is maximal with fentanyl and its variability is associated with changes in rSO₂. Fall in rSO₂ could be the common link triggering adverse HR-responses in BCP.

Control of Spinal Anesthesia-Induced Hypotension in Adults

Spinal anesthesia-induced hypotension (SAIH) occurs frequently, particularly in the elderly and in patients undergoing caesarean section. SAIH is caused by arterial and venous vasodilatation resulting from the sympathetic block along with a paradoxical activation of cardioinhibitory receptors. Bradycardia after spinal anesthesia (SA) must always be treated as a warning sign of an important hemodynamic compromise. Fluid preloading (before initiation of the SA) with colloids such as hydroxyethyl starch (HES) effectively reduces the incidence and severity of arterial hypotension, whereas crystalloid preloading is not indicated. Co-loading with crystalloid or colloid is as equally effective to HES preloading, provided that the speed of administration is adequate (ie, bolus over 5 to 10 minutes). Ephedrine has traditionally been considered the vasoconstrictor of choice, especially for use during SAIH associated with bradycardia. Phenylephrine, a α₁ adrenergic receptor agonist, is increasingly used to treat SAIH and its prophylactic administration (ie, immediately after intrathecal injection of local anesthetics) has been shown to decrease the incidence of arterial hypotension. The role of norepinephrine as a possible alternative to phenylephrine seems promising. Other drugs, such as serotonin receptor antagonists (ondansetron), have been shown to limit the blood pressure drop after SA by inhibiting the Bezold–Jarisch reflex (BJR), but further studies are needed before their widespread use can be recommended.

Complete atrioventricular dissociation and sinus arrest after pheochromocytoma resection

INTRODUCTION

Although preoperative bradycardia has been reported in several pheochromocytoma cases, postoperative bradycardia has not. This is the first case report of complete atrioventricular dissociation and sinus arrest occurring after pheochromocytoma resection.

CASE PRESENTATION

A 38-year-old woman was referred for a left adrenal incidentaloma. Twenty-four hour urinary collection showed elevated noradrenaline. Iodine-123-meta-iodobenzylguanidine scintigraphy showed high tracer uptake in the left adrenal region. Open left adrenalectomy was performed, and histopathological examination confirmed the diagnosis of pheochromocytoma. Thirty minutes following surgery, complete atrioventricular dissociation and sinus arrest developed. Vagal reflex attenuation due to decreased noradrenaline after tumor removal and perioperative pain and fear were believed to be the causes. A temporary pacemaker was implanted to prevent sudden death due to vagal overstimulation.

CONCLUSION

Vagal reflex attenuation after pheochromocytoma resection can result in complete atrioventricular dissociation and sinus arrest. Adequate preoperative preparation and close monitoring during and after surgery are imperative.

Differential Diagnostic Models Between Vasovagal Syncope and Psychogenic Pseudosyncope in Children

Objective: We aimed to establish useful models for the clinical differential diagnosis between vasovagal syncope (VVS) and psychogenic pseudosyncope (PPS). Methods: This bicentric study included 176 patients (150 VVS and 26 PPS cases) for model development. Based on the results of univariate and multivariate analyses, a logistic regression model and a scoring model were established and their abilities to differentiate VVS from PPS were tested. Another 78 patients (53 VVS and 25 PPS) were used for external validation. Results: In the logistic regression model, the outcome indicated that the QT-dispersion (QTd) (P < 0.001), syncope duration (P < 0.001), and upright posture (P < 0.001) acted as independent factors for the differentiation of VVS from PPS, which generated an area under the curve (AUC) of 0.892. A cutoff value of 0.234 yielded a sensitivity and specificity of 89.3 and 80.8%, respectively, for the differentiation between VVS and PPS in the logistic regression model. In the scoring model which consists of three variables, a cutoff score of three points yielded a sensitivity and specificity of 91.3 and 76.9%, respectively, with an AUC of 0.909. The external validation test indicated that the negative and positive predictive values of the scoring model were 78.8 and 91.7%, respectively, and the accuracy was 80.8%. Conclusion: The scoring model consisting of three variables is an easy-to-perform, inexpensive, and non-invasive measure for initial differential diagnosis between VVS and PPS.

Cardiovascular Changes and Lumbar Spine Surgery: A Neglected Entity

Cardiovascular changes following lumbar spine surgeries in the prone position have been less commonly described. Here, we report a case of an elderly male patient undergoing lumbar spine decompression and transforaminal interbody fusion who developed multiple but transient episodes of hypotension and bradycardia. Anesthesiologist should be vigilant while monitoring such patients and should use invasive blood pressure monitoring if possible, so as to detect transient cardiovascular episodes which may progress and results in a dreadful outcome.

ANESTHESIA OF AQUARIUM-HOUSED WALRUS ( ODOBENUS ROSMARUS): A CASE SERIES

  Walruses are a challenging species to anesthetize as a result of their large mass, limited access for drug delivery, unique physiology, and small number of reports describing anesthetic procedures. Three aquarium-housed walruses ( Odobenus rosmarus) ranging in age from 3 to 11 yr old (344-1,000 kg) were anesthetized for dental or ophthalmic surgical procedures, with one animal anesthetized twice and one anesthetized three times. Preanesthetic medication was with intramuscular midazolam (0.1-0.2 mg/kg) and meperidine (2-3 mg/kg). A catheter was placed in the extradural intravertebral vein, and anesthesia was induced with propofol to effect. Orotracheal intubation was performed and anesthesia maintained with isoflurane in oxygen using a circle breathing system connected to a ventilator. Intermittent positive pressure ventilation was used in all procedures. For the ophthalmic surgery, the neuromuscular blocking agent, cisatracurium, was given intravenously to provide a central eye and optimal surgical conditions. The neuromuscular block was antagonized with edrophonium. Total anesthesia times ranged from 1.5 to 6 hr. Midazolam and meperidine were antagonized with flumazenil and naltrexone, respectively, in five of six cases. Nonsteroidal anti-inflammatory agents were provided for analgesia. Recoveries were calm and uneventful. The described anesthetic protocols and case management were successful under the conditions encountered.

Effect of Intravenous Ondansetron on Spinal Anesthesia-Induced Hypotension and Bradycardia: A Randomized Controlled Double-Blinded Study

Background:

Spinal anesthesia is a safe anesthetic technique commonly practiced. However, it is associated with hypotension (33%), bradycardia (13%), and shivering which are induced by hypovolemia, sympathetic blockade, and Bezold–Jarisch reflex through intracardiac serotonin (5HT3) receptors and vagus nerve.

Aim:

To study the effect of intravenous (i.v.) ondansetron on hypotension and bradycardia induced by spinal anesthesia.

Setting and Design:

This was a randomized controlled double-blinded study done in a tertiary care teaching hospital.

Methods:

Of 140 patients, 70 in Group A received 2 mL of i.v. ondansetron 4 mg and 70 in the Group B received 2 mL of i.v. normal saline. 3 mL of 0.5% hyperbaric bupivacaine was injected intrathecally. Measurements of blood pressure and heart rate (HR) were taken every 3 min for 30 min after spinal anesthesia was performed. Mean arterial pressure (MAP) drop more than 20% was considered as incidence of hypotension and ephedrine 6 mg i.v. was given. HR drop >20% was regarded as bradycardia and atropine 0.5 mg i.v. was given.

Statistical Tests:

Quantitative data were analyzed using ANOVA test and qualitative data were analyzed using Chi-square test.

Results:

Both groups are comparable in demographic data. Four (5.7%) patients in Group B and no patients in Group A had incidence of bradycardia and atropine requirement (P = 0.120). There was no statistically significant difference in systolic blood pressure, diastolic blood pressure, and MAP. 19 (27%) patients in Group A and 33 (47.1%) in Group B required ephedrine with P = 0.029. 12 (17.1%) in Group B and no patients in Group A had shivering with P = 0.0001.

Conclusion:

Our study indicates that prophylactic use of ondansetron before spinal anesthesia significantly reduces the requirement of ephedrine and shivering.

Multiple asystole events in a patient undergoing total knee arthroplasty - a case report

Background

Unexpected cardiac arrest in patients during surgery is associated with high mortality. Reasons are often multifactorial and unclear.

Case presentation

This case report describes a patient who developed reversible asystole during knee surgery under general anaesthesia. All diagnostic cardiac examinations were unremarkable. After surgery, the patient showed no further symptoms.

Conclusion

To prevent cardiac arrest due to non-cardiac reasons, patients with a high risk for asystole caused by vasovagal reflex or by pain need to be identified. Preoperative conditions such as hypovolemia need to be improved prior to surgery, and additional monitoring should be used. Further investigations to determine the influence of non-cardiac disease and long-term medication are necessary.

Influence of anxiolytic premedication on vasovagal reactions and home readiness following outpatient intrathecal anaesthesia-A retrospective analysis

BACKGROUND

Vasovagal reactions during application of intrathecal anaesthesia (IA) are associated with high anxiety levels. A high percentage of patients undergoing outpatient surgery suffer from anxiety. Anxiolytic premedication in day-surgery is suspected to delay recovery and discharge and is, therefore, not routinely used. The aim of this retrospective analysis was to detect the influence of anxiolytic premedication on the incidence of vasovagal reactions and time until discharge home.

METHODS

Anaesthesia records of all patients undergoing outpatient surgery under low-dose IA from January 2008 to June 2017 were analysed. Incidences of vasovagal reactions with a decrease in blood pressure and/or heart rate and need for cardiovascular activating medications were documented. Patients were categorised as having received an anxiolytic premedication or not. The time from intrathecal injection of the local anaesthetic until readiness for discharge was recorded.

RESULTS

The records of 2747 patients were analysed. One thousand two hundred and ninety-one of them received an anxiolytic premedication of 1-2 mg midazolam intravenously. Three hundred and fourteen patients had vasovagal incidents during application of IA (no premedication n = 217 [15.0%], premedication n = 97 [7.5%], P < 0.0001). Premedication did not prolong time to achieve readiness for discharge (mepivacaine: P = 0.5886, chloroprocaine: P = 0.1555). However, in the prilocaine group, premedication led to a significantly earlier achievement of readiness for discharge (P = 0.0002).

CONCLUSION

Anxiolytic premedication significantly reduces the incidence of vasovagal reactions during the application of IA and does not affect time until readiness for discharge.

Left Ventricular Ejection Fraction and Fractional Shortening are Useful for the Prediction of the Therapeutic Response to Metoprolol in Children with Vasovagal Syncope

The objective of this manuscript was to explore if left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) could predict the efficacy of metoprolol therapy on vasovagal syncope (VVS) in children. Forty-nine children, including 30 with VVS and 19 gender- and age-matched healthy controls, were included in the study. Metoprolol was prescribed to the VVS subjects. The clinical data were obtained during follow-up at 2 and 6 months. The results showed that LVEF and LVFS of responders were significantly higher than those of non-responders both at the 2-month follow-up (LVEF: 72.5 ± 3.2% vs. 64.6 ± 3.4%; LVFS: 40.9 ± 2.3% vs. 34.9 ± 2.9%), and at the 6-month follow-up (LVEF: 72.8 ± 2.8% vs. 65.5 ± 4.6%; LVFS: 41.1 ± 1.9% vs. 35.8 ± 3.6%). The receiver operating characteristic curve (ROC) analysis demonstrated that 70.5% as a cutoff value of baseline LVEF yielded a sensitivity of 80% and a specificity of 100% in predicting the therapeutic effectiveness of metoprolol at 2 months. For baseline LVFS, 38.5% as a cutoff value yielded a sensitivity of 90% and a specificity of 90%. At the 6-month follow-up, the ROC analysis demonstrated that 70.5% as a cutoff value of baseline LVEF yielded a sensitivity of 81.3% and a specificity of 88.9% in the prediction of metoprolol efficacy. For baseline LVFS, 37.5% as a cutoff value yielded a sensitivity of 93.8% and a specificity of 66.7%. In conclusion, baseline LVEF and LVFS might be useful predictors of the efficacy of β-blocker therapy on VVS in children.