Left Atrial Appendage Exclusion Using the AtriClip Device: A Case Series.

BACKGROUND: Atrial fibrillation (AF) affects 1.5-2% of the population and is associated with a five-fold increased lifetime risk of stroke [1]. The left atrial appendage (LAA) is the source of embolic strokes in up to 90% of patients with non-valvular AF with clots in the left atrium [2]. METHODS: We reviewed the clinical notes and echocardiographic findings of 20 patients who underwent open cardiac surgery in which concurrent AtriClip (Atricure Inc, Westchester, OH, USA) device insertion was attempted at our institution from July 2013 to February 2015. This was to examine the safety and efficacy of LAA exclusion with clip devices during open cardiac surgery. Indications for LAA exclusion included a history or suspicion of atrial arrhythmia, left ventricular dilatation, or a history of transient ischaemic attacks. RESULTS: All 20 of the 20 participants had successful placement of the clip device (100% success rate). There were no adverse events related to the device and no perioperative mortality. There were three late deaths due to chronic obstructive pulmonary disease (COPD), leukaemia, and refractory congestive cardiac failure. No late device related complications were found on follow-up imaging in the remaining patients. CONCLUSIONS: The results of our study demonstrate the LAA exclusion during open cardiac surgery with the AtriClip device is safe, has a 100% success rate, and appears to be stable over time.

Determining the Optimal Dose of Adenosine for Unmasking Dormant Pulmonary Vein Conduction Following Atrial Fibrillation Ablation: Electrophysiological and Hemodynamic Assessment. DORMANT-AF Study.

INTRODUCTION: ELECTROPHYSIOLOGICAL AND HEMODYNAMIC ASSESSMENT. DORMANT-AF STUDY: The significance of adenosine induced dormant pulmonary vein (PV) conduction in atrial fibrillation (AF) ablation remains controversial. The optimal dose of adenosine to determine dormant PV conduction is yet to be systematically explored. METHODS AND RESULTS: ELECTROPHYSIOLOGICAL AND HEMODYNAMIC ASSESSMENT. DORMANT-AF STUDY: Consecutive patients undergoing index AF ablation received 3 adenosine doses (12, 18, and 24 mg) in a randomized blinded order, immediately after pulmonary vein isolation (PVI). Electrophysiological (PR prolongation, AV block (AVB) and PV reconnection) and hemodynamic (BP) parameters were measured. A total, 339 doses (113/dose) assessed 191 PVs in 50 patients (66% male, 72% PAF, 52% hypertensive). Dormant PV conduction occurred in 28% of patients (16.5% [32] of PVs). All cases were associated with AVB (AVB: PV reconnection vs. no PV reconnection 100% vs. 83%, P = 0.007). AVB occurred more frequently at 24 mg versus 12 mg (92% vs. 82%, P = 0.019) but not versus 18 mg (91%, P = 0.62). AVB duration progressed between 12 mg (12.0 ± 8.9 seconds), 18 mg (16.1 ± 9.1 seconds, P = 0.001), and 24 mg (19.0 ± 9.3 seconds, P < 0.001) doses. MBP fell further at 24 mg (ΔMBP: 27 ± 12 mmHg) and 18 mg (26 ± 13 mmHg) doses compared to 12 mg (22 ± 10 mmHg vs., P < 0.001). A significant reduction in AVB in patients >110 kg (65% vs. 91% in 70-110 kg group, P < 0.001) in response to adenosine was seen. CONCLUSION: ELECTROPHYSIOLOGICAL AND HEMODYNAMIC ASSESSMENT. DORMANT-AF STUDY: An adenosine dose producing AVB is required to unmask dormant PV conduction. AVB is significantly reduced in patients >110 kg. Weight and dosing variability may in part explain the conflicting results of studies evaluating the clinical utility of adenosine in PVI.

Evaluation of the brain anaesthesia response monitor during anaesthesia for cardiac surgery: a double-blind, randomised controlled trial using two doses of fentanyl.

The brain anaesthesia response (BAR) monitor uses a method of EEG analysis, based on a model of brain electrical activity, to monitor the cerebral response to anaesthetic and sedative agents via two indices, composite cortical state (CCS) and cortical input (CI). It was hypothesised that CCS would respond to the hypnotic component of anaesthesia and CI would differentiate between two groups of patients receiving different doses of fentanyl. Twenty-five patients scheduled to undergo elective first-time coronary artery bypass graft surgery were randomised to receive a total fentanyl dose of either 12 µg/kg (fentanyl low dose, FLD) or 24 µg/kg (fentanyl moderate dose, FMD), both administered in two divided doses. Propofol was used for anaesthesia induction and pancuronium for intraoperative paralysis. Hemodynamic management was protocolised using vasoactive drugs. BIS, CCS and CI were simultaneously recorded. Response of the indices (CI, CCS and BIS) to propofol and their differences between the two groups at specific points from anaesthesia induction through to aortic cannulation were investigated. Following propofol induction, CCS and BIS but not CI showed a significant reduction. Following the first dose of fentanyl, CI, CCS and BIS decreased in both groups. Following the second dose of fentanyl, there was a significant reduction in CI in the FLD group but not the FMD group, with no significant change found for BIS or CCS in either group. The BAR monitor demonstrates the potential to monitor the level of hypnosis following anaesthesia induction with propofol via the CCS index and to facilitate the titration of fentanyl as a component of balanced anaesthesia via the CI index.

Ultrasound-guided thoracic paravertebral blockade: a cadaveric study.

BACKGROUND: Multiple approaches to the paravertebral space have been described to produce analgesia after thoracic surgery. Ultrasound-guided regional anesthesia has the potential to improve efficacy and reduce complications via real-time visualization of the paravertebral space, surrounding structures, and the approaching needle. We compared a single- versus dual-injection technique for ultrasound-guided paravertebral blockade in a cadaver model, evaluating the spread of contrast dye and location of a catheter. METHODS: Thirty paravertebral injections and 20 catheter placements were performed on 10 fresh cadavers. The paravertebral space was identified using an ultrasound probe in the transverse plane using a linear transducer. An in-plane needle approach was used. Using analine contrast dye, a single 20-mL injection at T6-7 on one side and a dual-injection technique of 10 mL at T3-4 and T7-8 on the contralateral side were performed on each cadaver, followed by insertion of a catheter through the needle. The cadaver was then dissected to evaluate spread of contrast dye and catheter location. RESULTS: The paravertebral space was easily identified with ultrasound on each cadaver. Contrast dye was seen to surround somatic and sympathetic nerves in the paravertebral, intercostal, and epidural spaces. Contrast dye was present in 19 of 20 paravertebral spaces over 3 to 4 segments (range, 0-10) with no significant differences between single- and dual-injection techniques. Contrast dye spread more extensively across intercostal segments with 4.5 spaces (range, 2-10) covered with a single injection and 6 spaces (range, 2-8) covered with a dual-injection technique (P = 0.03). There was epidural spread of contrast in 40% of paravertebral injections in both single- and dual-injection techniques. Catheters were located in the paravertebral space (60%), prevertebral space (20%), and epidural space (5%). CONCLUSIONS: Transverse in-plane ultrasound-guided needle insertion into the thoracic paravertebral space is both feasible and reliable. However, paravertebral spread of contrast is highly variable with intercostal and epidural spread likely contributing significantly to the analgesic efficacy. A dual-injection technique at separate levels seems to cover more thoracic dermatomes because of greater segmental intercostal spread (rather than paravertebral spread) than a single-injection approach. Catheters are located in nonideal positions in 40% of cases using this in-plane technique.

The use of air in the inspired gas mixture during two-lung ventilation delays lung collapse during one-lung ventilation.

BACKGROUND: Collapse of the ipsilateral lung facilitates surgical exposure during thoracic procedures. The use of different gas mixtures during two-lung ventilation (2LV) may improve or impede surgical conditions during subsequent one-lung ventilation (OLV) by increasing or delaying lung collapse. We investigated the effects of three different gas mixtures during 2LV on lung collapse and oxygenation during subsequent OLV: Air/Oxygen (fraction of inspired oxygen [FIO(2)] = 0.4), Nitrous Oxide/Oxygen ("N(2)O," FIO(2) = 0.4) and Oxygen ("O(2)," FIO(2) = 1.0). METHODS: Subjects were randomized into three groups: Air/Oxygen (n = 33), N(2)O (n = 34) or O(2) (n = 33) and received the designated gas mixture during induction and until the start of OLV. Subjects' lungs in all groups were then ventilated with FIO(2) = 1.0 during OLV. The surgeons, who were blinded to the randomization, evaluated the lung deflation using a verbal rating scale at 10 and 20 min after the start of OLV. Serial arterial blood gases were performed before anesthesia induction, during 2LV, and every 5 min, for 30 min, after initiation of OLV. RESULTS: The use of air in the inspired gas mixture during 2LV led to delayed lung deflation during OLV, whereas N(2)O improved lung collapse. Arterial oxygenation was significantly improved in the O(2) group only for the first 10 min of OLV, after which there were no differences in mean Pao(2) values among groups. CONCLUSIONS: De-nitrogenation of the lung during 2LV is a useful strategy to improve surgical conditions during OLV. The use of FIO(2) 1.0 or N(2)O/O(2) (FIO(2) 0.4) during 2LV did not have an adverse effect on subsequent oxygenation during OLV.

Novel Preoxygenation Technique to Deliver High-Flow Oxygen in a Patient With Facial Trauma: A Case Report.

This case demonstrates a novel preoxygenation technique in a patient with difficult access to the airway after a traumatic facial injury. To find a solution, a fusion of oxygenation equipment was trialed by altering and combining a tracheostomy mask and the tubing of an Optiflow circuit from which the nasal cannula component had been removed. This novel combination delivered high-flow humidified oxygen (60 L/min) orally, avoided further facial injury, and was well tolerated by the patient. Effective preoxygenation was confirmed by arterial gas measurements. This study supports the use of this novel Optiflow-tracheostomy mask fusion device in appropriately selected cases.

A comparison of dexmedetomidine versus conventional therapy for sedation and hemodynamic control during carotid endarterectomy performed under regional anesthesia.

The properties of dexmedetomidine (DEX) that result in titratable sedation and sympathetic modulation suggest that it would be suitable for use during carotid endarterectomy (CEA) performed under regional anesthesia. We performed a randomized, double-blind study in 56 patients having CEA under regional anesthesia and compared hemodynamic control using DEX versus a conventional sedation technique using midazolam and fentanyl standard (STD). Sedation was titrated to a Ramsay Sedation Score of 2-4 in both groups. The primary outcome was the number of pharmacological interventions required to treat deviations of arterial blood pressure and heart rate outside of predetermined limits. We also compared recovery hemodynamic profiles, patient satisfaction, and adverse cardiac and neurological events. There was no difference in the overall rate of hemodynamic interventions (DEX 80% versus STD 79%; P = 1.0). However, the nature of interventions differed in that patients in the DEX group were less likely to require treatment for hypertension and/or tachycardia (DEX 40% versus STD 72%; P = 0.03). The number of interventions per patient for hypertension and/or tachycardia was also lesser in the DEX group (P = 0.02). There were no significant differences in the numbers of patients needing intraoperative treatment for hypotension or bradycardia or in the need for intraarterial shunting. In the postanesthesia care unit, more patients in the DEX group required hemodynamic drug interventions (DEX 11, 44%, versus STD 4, 14%; P = 0.03). These were primarily for hypotension (DEX 7, 28% versus STD 3, 11%; P = 0.16). The number of patients requiring no additional pain relief in the postanesthesia care unit was significantly larger for patients in the DEX group (DEX 18, 72% versus STD 11, 38%; P = 0.027). DEX provides an acceptable alternative, without superiority to standard techniques for sedation during awake CEA.