Efficacy and safety of a new protocol for continuous infusion of midazolam and fentanyl and its effects on patient distress during electrophysiological studies

Anesthetic management of children undergoing drug-induced sleep endoscopy: A retrospective review

OBJECTIVE

To determine the best anesthetic technique for DISE based on a retrospective review of the current literature and to highlight research gaps that should be addressed in future studies.

METHODS

A comprehensive retrospective review of the literature on anesthetic regimens for pediatric DISE through March 2020 was performed. Specific medical subject heading (MesH) terms included: drug-induced sleep endoscopy and anesthesia, DISE, child, obstructive sleep apnea, sleep disordered breathing.

RESULTS

Twelve articles were included. One study was a retrospective comparative study while the remaining 11 were case series. Five studies described anesthetic technique for DISE pre-T&A, two post-T&A, and four both pre- and post-T&A. The heterogeneity of the studies did not allow for a meta-analysis. A total of 1110 children ages 2 months to 19 years were included. Sedation depth and anesthetic outcomes with DISE were infrequently described. Eleven studies used a sevoflurane inhalational induction and mostly transitioned to a total IV anesthetic for maintenance. Propofol was the most commonly used sole anesthetic. A total of three studies used a combination of remifentanil and propofol, one used dexmedetomidine alone, one used sevoflurane alone, and one compared different regimens. Dexmedetomidine and ketamine have the most favorable profile for pediatric DISE but are not universally used. DISE completion, as reported in two studies, was 93% and 100%.

CONCLUSION

There are several anesthetic regimens for DISE that achieve good sedation and outcomes. The combination of ketamine and dexmedetomidine may be the ideal regimen. Limited data and lack of protocols/high-quality studies exist on anesthetic regimens for pediatric DISE.

Effects of morphine on respiratory load detection, load magnitude perception, and tactile sensation in obstructive sleep apnea

Pharyngeal and respiratory sensation is impaired in obstructive sleep apnea (OSA). Opioids may further diminish respiratory sensation. Thus protective pharyngeal neuromuscular and arousal responses to airway occlusion that rely on respiratory sensation could be impaired with opioids to worsen OSA severity. However, little is known about the effects of opioids on upper airway and respiratory sensation in people with OSA. This study was designed to determine the effects of 40 mg of MS-Contin on tactile sensation, respiratory load detection, and respiratory magnitude perception in people with OSA during wakefulness. A double-blind, randomized, crossover design (1 wk washout) was used. Twenty-one men with untreated OSA (apnea/hypopnea index = 26 ± 17 events/h) recruited from a larger clinical study completed the protocol. Tactile sensation using von Frey filaments on the back of the hand, internal mucosa of the cheek, uvula, and posterior pharyngeal wall were not different between placebo and morphine [e.g., median (interquartile range) posterior wall = 0.16 (0.16, 0.4) vs. 0.4 (0.14, 1.8) g, P = 0.261]. Similarly, compared with placebo, morphine did not alter respiratory load detection thresholds for nadir mask pressure detected = −2.05 (−3.37, −1.55) vs. −2.19 (−3.36, −1.41) cmH2O, P = 0.767], or respiratory load magnitude perception [mean ± SD Borg scores during a 5 resistive load (range: 5–126 cmH2O·l−1·s−1) protocol = 4.5 ± 1.6 vs. 4.2 ± 1.2, P = 0.347] but did reduce minute ventilation during quiet breathing (11.4 ± 3.3 vs. 10.7 ± 2.6 l/min, P < 0.01). These findings indicate that 40 mg of MS-Contin does not systematically impair tactile or respiratory sensation in men with mild to moderate, untreated OSA. This suggests that altered respiratory sensation to acute mechanical stimuli is not likely to be a mechanism that contributes to worsening of OSA with a moderate dose of morphine.

NEW & NOTEWORTHY Forty milligrams of MS-Contin does not alter upper airway tactile sensation, respiratory load detection thresholds, or respiratory load magnitude perception in people with obstructive sleep apnea but does decrease breathing compared with placebo during wakefulness. Despite increasing concerns of harm with opioids, the current findings suggest that impaired respiratory sensation to acute mechanical stimuli with this dose of MS-Contin is unlikely to be a direct mechanism contributing to worsening sleep apnea severity in people with mild-to-moderate disease.

Sedation in cardiac arrhythmias management

INTRODUCTION

Procedural sedation is of paramount importance for a plethora of electrophysiological procedures. From electrical cardioversion to electrophysiology studies, device implantations, and catheter ablations, intraprocedural sedation and anesthesia have a pivotal role in allowing procedural success while ensuring patient safety and avoiding discomfort. Areas covered: The present review will discuss the current state-of-the-art in sedation and anesthesia during electrical cardioversion, cardiac implantable electronic device implantation, catheter ablation and electrophysiology studies. Specific information will be provided for each procedure in order to reach the core of this important clinical issue, and specific protocols will be compared. The main pro-arrhythmic and anti-arrhythmic effects of the most commonly used sedatives will also be discussed. Expert commentary: According to much recent evidence, the cardiologist can be the only person responsible for sedation administration in many settings, highlighting few safety issues associated with the absence of a dedicated anesthesiologist thus a concomitant reduction in costs. However, many concerns have been raised in allowing non-anesthesiologists to manage sedatives, as adverse events, while rare, could have catastrophic consequences. The present paper will highlight when a cardiologist-directed sedation is considered safe, how it should be performed, and the pros and cons related to this strategy.

Sedation for electrophysiological procedures

Administration of intravenous sedation (IVS) has become an integral component of procedural cardiac electrophysiology. IVS is employed in diagnostic and ablation procedures for transcutaneous treatment of cardiac arrhythmias, electrical cardioversion of arrhythmias, and the insertion of implantable electronic devices including pacemakers, defibrillators, and loop recorders. Sedation is frequently performed by nursing staff under the supervision of the proceduralist and in the absence of specialist anesthesiologists. The sedation requirements vary depending on the nature of the procedure. A wide range of sedation techniques have been reported with sedation from the near fully conscious to levels approaching that of general anesthesia. This review examines the methods employed and outcomes associated with reported sedation techniques. There is a large experience with the combination of benzodiazepines and narcotics. These drugs have a broad therapeutic range and the advantage of readily available reversal agents. More recently, the use of propofol without serious adverse events has been reported. The results provide a guide regarding the expected outcomes of these approaches. The complication rate and need for emergency assistance is low in reported series where sedation is administered by nonspecialist anesthesiology staff.

Electrophysiological features in patients with sinus node dysfunction and vasovagal syncope

INTRODUCTION

Syncope is a common presentation of sinus node dysfunction (SND). Some patients who receive a permanent pacemaker due to SND do not benefit from it and further diagnostic workup leads to the diagnosis of vasovagal syncope (VVS). The aim of the study was to identify electrophysiological criteria that can be used for identification of patients with SND and concurrent VVS.

MATERIAL AND METHODS

Transoesophageal atrial pacing (TAP) was performed in 100 patients divided into four groups depending on symptoms and TAP results. Standard electrophysiological parameters of sinus node function and their variability were obtained in the basal state and after pharmacological autonomic blockade (AB).

RESULTS

Patients with concurrent SND and VVS had a greater variability of sinoatrial conduction time assessed by Strauss' method than patients without incidents of syncope (83.2 ±53.9 vs. 34.1 ±19.6, 47.8 ±33.6 and 32.1 ±22.99). Apart from abnormal sinus node recovery time and second pause, patients with SND had bigger basal state variability of these parameters. In patients with SND and concurrent vasovagal syncope the variability of sinus node recovery time (SNRT), corrected SNRT (cSNRT) and second pause (IIP) decreased after autonomic blockade.

CONCLUSIONS

Patients with concurrent SND and VVS have distinct electrophysiological features - greater sinoatrial conduction time (SACT) variability and the decrease of SNRT, cSNRT and IIP variability after AB. However, further studies in larger study groups are needed to validate our findings. Transoesophageal atrial pacing is a useful procedure in patients with syncope, especially when the coexistence of more than one cardiac cause is suspected.

Atrial Arrhythmias After Single-Ring Isolation of the Posterior Left Atrium and Pulmonary Veins for Atrial Fibrillation

Background— Single-ring isolation of the posterior left atrium is feasible, but the incidence and mechanisms of postprocedural arrhythmias have not been described in detail.

Methods and Results— The first 100 consecutive patients (58.8�11.2 years old, 80 male) who underwent single-ring isolation for atrial fibrillation (66 intermittent, 18 persistent, 16 long-standing persistent) were followed up for 9.1�4.5 months. Recurrences were diagnosed by clinical symptoms and Holter monitoring. Patients with recurrences of sustained atrial arrhythmia >3 months after the procedure were offered a repeat procedure and were studied to determine the mechanisms of recurrence. Forty-six patients (46%) experienced sustained postprocedural atrial arrhythmias (35 had atrial fibrillation, and 34 had atrial flutter). Of these, 34 required a second procedure 7.0�3.1 months after their initial procedure. Reconnection of the posterior left atrium was seen in all patients with atrial fibrillation. Atrial flutter was most commonly due to mitral isthmus-dependent macroreentry (n=8, cycle length 368�116 ms) or macroreentry through 2 gaps in the ring of lesions (n=6, cycle length 328�115 ms). Posterior left atrium reisolation was achieved at the second procedure in all patients. Atrial flutter was successfully ablated and rendered noninducible in all patients. Six months after their last procedure, the Kaplan-Meier estimate of freedom from recurrence for all 100 patients was 81�5%.

Conclusions— Atrial fibrillation and atrial flutter recurrence is common after single-ring isolation. Reconnection of the posterior left atrium and macroreentry are the common mechanisms. Repeat ablation results in satisfactory short-term outcomes.

Cardiology at Westmead Hospital from 1990 to 2007

Professor John Uther was the Director of Cardiology at Westmead Hospital from 1979 to 1990. Professor David Ross and Dr Pramesh Kovoor followed in this capacity subsequently. Networking between Westmead and metropolitan hospitals was established by conjoint appointment of cardiologists across the facilities. Westmead has maintained its excellence in electrophysiology with leadership in operative/catheter ablation of atrial fibrillation, development of catheter for mapping tricuspid annulus, multi-electrode mapping and intramural ablation of ventricular tachycardia and paediatric electrophysiology. Dr. Hugh Paterson became the Director of Cardiothoracic Surgery in 2006. The previous Directors were Dr. David Johnson, Dr. Graham Nunn and Associate Professor Richard Chard. Westmead established an area-wide acute infarct angioplasty service for all patients presenting to any facility in Western Sydney along with triage of chest pain in the ambulance in 2004. Collaborative sessions with vascular surgeons for non-coronary interventions commenced in 2005. In the future, Westmead will continue its excellence in vascular and electrophysiological interventions. Imaging (echocardiography, computerised tomography and magnetic resonance imaging) will be a major part of the service. Innovation in basic science is likely. Overall, it will be an exciting time to be a cardiologist, vascular surgeon or cardiothoracic surgeon at Westmead.

Percutaneous pulmonary vein isolation for treatment of atrial fibrillation

BACKGROUND

Transvenous catheter ablation for the treatment of atrial fibrillation is an evolving technique.

AIM

The purpose of this study was to identify subgroups of patients most likely to benefit from pulmonary vein electrical isolation.

METHODS

Patients with symptomatic atrial fibrillation resistant to pharmacological therapy were studied. Mapping-guided segmental application of radio-frequency energy was used to electrically isolate the pulmonary veins in 74 patients. Ischaemic or dilated cardiomyopathy was present in 34% of patients. Atrial fibrillation had been present for a mean time (+/- standard deviation) of 6.6 +/- 6.1 years. It was paroxysmal in 53 patients (72%).

RESULTS

The mean number of procedures was 1.6/patient. After 6 +/- 6 months, 73% of patients (54/74) were in sinus rhythm. Thirteen of those in sinus rhythm were using anti-arrhythmic medications (25%). Recurrence of atrial fibrillation soon after pulmonary vein isolation occurred in 50%. Patients with persistent/permanent atrial fibrillation were less likely to be in sinus rhythm at follow up (11/21 (52%) vs 43/53 (81%); P = 0.01). However, the rate of early recurrence was similar in the intermittent and the persistent/permanent groups (26/53 (49%) vs 11/21(52%), respectively; P-value not significant). Patients with persistent atrial fibrillation were more likely to experience a recurrence of atrial fibril-lation (89%; P = 0.04). No other baseline factors predicted procedural success. Cardiac tamponade occurred in two patients and moderate pulmonary vein stenosis (>50% diameter narrowing) occurred in three patients.

CONCLUSIONS

Pulmonary vein isolation is an effective curative treatment for a broad group of patients with atrial fibrillation. However, the procedure is only suitable for patients with problematic atrial fibrillation resistant to other therapies because of the small risk of serious complications.

Conscious sedation with intermittent midazolam and fentanyl in electrophysiology procedures

OBJECTIVES

To determine the safety and efficacy of intermittent midazolam and fentanyl conscious sedation for electrophysiology procedures (EP).

BACKGROUND

Intermittent midazolam and fentanyl conscious sedation was administered in 700 consecutive cases (175 radiofrequency ablations, 163 EP studies, 261 pacemakers, and 101 implantable cardioverter-defibrillators) for 471 patients (239 males, 51%) mean age 65 +/- 15 years. The mean dose of midazolam was 0.063 mg/kg/hr and fentanyl was 0.591 microgram/kg/hr.

METHODS

Cardiac rate and rhythm were monitored continuously, while blood pressure and arterial oxygen saturation were noninvasively assessed every 5 minutes. Drugs were administered in aliquots of 0.5 to 2.0 mg of midazolam and 6.25 to 25 micrograms of fentanyl as determined by clinical condition every 15 to 30 minutes.

RESULTS

There were no deaths. In no case was endotracheal intubation required. Mild hypoxemia (SaO2 > 80%, but < 90%) occurred in 17 cases (2.4%) and was easily reversed with verbal stimulation and oropharyngeal repositioning (12 cases, 1.7%), increased F1O2 (3 cases, 0.4%), or intravenous naloxone (2 cases, 0.3%). Reversible hypotension (systolic blood pressure < 90, but > 60 mmHg) occurred in 14 patients (2.0%) and was corrected with intravenous crystalloid bolus or flumazenil (10 cases, 1.4%) or inotrope infusion (4 cases, 0.6%). No patient stay was prolonged due to sedation. Only five patients (0.7%) had any recollection of the procedure, while two (0.3%) were aware of pain. All hypoxemic episodes occurred during the first hour, whereas 43% (6/14) of hypotensive episodes occurred after the first hour.

CONCLUSION

Conscious sedation with intermittent midazolam and fentanyl is safe and efficacious for a broad range of EP procedures.

Usefulness of intravenous propofol anesthesia for radiofrequency catheter ablation in patients with tachyarrhythmias: infeasibility for pediatric patients with ectopic atrial tachycardia

General anesthesia is sometimes required during radiofrequency catheter ablation (RFCA) of various tachyarrhythmias because of an anticipated prolonged procedure and the need to ensure stability during critical ablation. In this study, we examine the feasibility of using propofol anesthesia for RFCA procedure. There were 150 patients (78 male, 72 female; mean age 30 years, range 4-96 years) in the study. Electrophysiologic study was performed before and during propofol infusion in the initial 20 patients and was performed only during propofol infusion in the remaining 130 patients. In the initial 20 patients, propofol infusion increased the sinus rate and facilitated AV nodal conduction. The accessory pathway effective refractory period, as well as the sinus node recovery time, atrial effective refractory period, and ventricular effective refractory period were not significantly changed. There were 152 tachyarrhythmias in 150 patients (24 atrial flutter, 31 AV nodal reentrant tachycardia, 68 AV reciprocating tachycardia, 12 ventricular tachycardia, and 17 atrial tachycardia). Most (148/152) tachycardias remained inducible after anesthesia and RFCA was performed uneventfully. However, in four of the seven pediatric patients with ectopic atrial tachycardia, the tachycardia terminated after propofol infusion and could not be induced by isoproterenol infusion. Consequently, RFCA could not be performed. Intravenous propofol anesthesia is feasible during RFCA for most tachyarrhythmias except for ectopic atrial tachycardia in children.