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Cardiac Electrophysiology Clinics Sep 2020The pericardial cavity and its boundaries are formed by the reflections of the visceral and parietal pericardial layers. This space is an integral access point for... (Review)
Review
The pericardial cavity and its boundaries are formed by the reflections of the visceral and parietal pericardial layers. This space is an integral access point for epicardial interventions. As the pericardial layers reflect over the great vessels and the heart, they form sinuses and recesses, which restrict catheter movement. The epicardial vasculature is also important when performing nearby catheter ablation. The phrenic nerve and esophagus are other important structures to appreciate so as to avoid collateral injury. In addition, the Larrey space, or left sternocostal triangle, is a key avascular window through which pericardial access can be safely achieved.
Topics: Catheter Ablation; Coronary Vessels; Electrophysiologic Techniques, Cardiac; Esophagus; Humans; Pericardium; Phrenic Nerve
PubMed: 32771181
DOI: 10.1016/j.ccep.2020.04.003 -
ANZ Journal of Surgery Mar 2023Neck dissection is a commonly performed procedure for oncologic control of head and neck malignancy. With contemporary modified radical and selective neck dissections,... (Review)
Review
BACKGROUND
Neck dissection is a commonly performed procedure for oncologic control of head and neck malignancy. With contemporary modified radical and selective neck dissections, haematoma, wound infection, tissue necrosis, chyle leak and injury involving the marginal mandibular, hypoglossal, vagus or accessory nerves are commonly described complications. Although the phrenic nerve courses within the surgical planes explored during a neck dissection and has a vital function in innervating the diaphragm, few studies have been performed to investigate the exact incidence of post-operative phrenic nerve paresis. This study aims to review the literature as to the rate of phrenic nerve injury following neck dissection.
METHODS
A systematic literature review was conducted from 2000 to 2022 including studies reporting on phrenic nerve paresis following neck dissection.
RESULTS
In total, 11 studies were included. The reported rate of immediate post-operative phrenic nerve paresis ranged from 0% to 5.3%, with an average rate of 0.613% (12/1959). The reported rate of phrenic nerve paresis at follow-up (1 month-127 months) ranged from 0% to 4.7%, with an average rate of 1.035% (5/483). There were no cases of bilateral phrenic nerve paresis reported in this period.
CONCLUSIONS
Phrenic nerve paresis is an uncommon complication following neck dissection, often asymptomatic and potentially underreported. Bilateral phrenic nerve paresis is exceedingly rare. Injury can be avoided by staying superficial to the prevertebral fascia when dissecting around the anterior scalene muscle. Routine phrenic nerve integrity monitoring is not commonly utilized but may aid intra-operative phrenic nerve identification or confirmation of function.
Topics: Humans; Phrenic Nerve; Neck Dissection; Head and Neck Neoplasms; Paresis
PubMed: 36792555
DOI: 10.1111/ans.18322 -
Journal of Clinical Neurophysiology :... May 2020Patients with intensive care unit-acquired weakness have an increased risk of prolonged mechanical ventilation, which is a risk factor for prolonged stay and mortality.... (Review)
Review
Patients with intensive care unit-acquired weakness have an increased risk of prolonged mechanical ventilation, which is a risk factor for prolonged stay and mortality. The most common cause of this problem is weakness of the diaphragm, which can derive from phrenic nerve injury associated with critical neuropathy, or with the complex multiorgan failure/systemic respiratory response syndrome causing muscle fiber lesion. Two conventional neurophysiological techniques are useful to investigate the respiratory muscles, phrenic nerve conduction, and needle electromyography of the accessory respiratory muscles and diaphragm. Phrenic nerve stimulation is a standard noninvasive technique; amplitude of the motor response can be reduced because of muscle fiber inexcitability or axonal loss. Electromyography of the diaphragm is an invasive method but is safe if performed as indicated. It can reveal neurogenic or myopathic motor units. Although these neurophysiological methods have limitations in the investigation of intensive care unit patients with severe respiratory involvement, normal phrenic nerve responses should exclude marked axonal loss and indicate a better prognosis.
Topics: Critical Care; Diaphragm; Electromyography; Female; Humans; Intensive Care Units; Muscle Weakness; Neurophysiology; Phrenic Nerve
PubMed: 32358247
DOI: 10.1097/WNP.0000000000000663 -
The Annals of Thoracic Surgery Sep 2022In appropriately selected patients diaphragm plication improves quality of life by alleviating dyspnea and allowing patients to return to their routine activities. Many...
In appropriately selected patients diaphragm plication improves quality of life by alleviating dyspnea and allowing patients to return to their routine activities. Many plication techniques exist, but the optimal surgical approach remains unclear. We report our experience with a minimally invasive radial diaphragm plication technique. It offers 2 distinct advantages: (1) suture placement avoids the phrenic nerve fibers, allowing for potential nerve recovery, and (2) the interrupted radial sutures improve the distribution of tension along the flaccid muscle and may achieve a more durable repair.
Topics: Diaphragm; Humans; Phrenic Nerve; Quality of Life; Respiratory Paralysis; Sutures
PubMed: 34951968
DOI: 10.1016/j.athoracsur.2021.11.037 -
Life (Basel, Switzerland) Sep 2023To restore elbow flexor muscle function in case of traumatic brachial plexus avulsion, the phrenic nerve transfer to the musculocutaneous nerve has become part of...
BACKGROUND
To restore elbow flexor muscle function in case of traumatic brachial plexus avulsion, the phrenic nerve transfer to the musculocutaneous nerve has become part of clinical practice. The nerve transfer can be done by means of video-assisted thoracic surgery without nerve graft or via supraclavicular approach in combination with an autograft. This study focuses on a detailed microscopic and macroscopic examination of the phrenic nerve. It will allow a better interpretation of existing clinical results and, thus, serve as a basis for future clinical studies.
MATERIAL AND METHODS
An anatomical study was conducted on 28 body donors of Caucasian origin (female n = 14, male n = 14). A sliding caliper and measuring tape were used to measure the diameter and length of the nerves. Sudan black staining was performed on 15 µm thick cryostat sections mounted on glass slides and the number of axons was determined by the ImageJ counting tool. In 23 individuals, the phrenic nerve could be examined on both sides. In 5 individuals, however, only one side was examined. Thus, a total of 51 nerves were examined.
RESULTS
The mean length of the left phrenic nerves (33 cm (29-38 cm)) was significantly longer compared to the mean length of the right phrenic nerves (30 cm (24-33 cm)) ( < 0.001). Accessory phrenic nerves were present in 9 of 51 (18%) phrenic nerves. The mean number of phrenic nerves axons at the level of the first intercostal space in body donors with a right accessory phrenic nerve was significantly greater compared to the mean number of phrenic nerves axons at the same level in body donors without a right accessory phrenic nerve (3145 (range, 2688-3877) vs. 2278 (range, 1558-3276)), = 0.034. A negative correlation was registered between age and the nerve number of axons in left (0.742, < 0.001) and right (-0.273, = 0.197) phrenic nerves. The mean distance from the upper edge of the ventral ramus of the fourth cervical spinal nerve to the point of entrance of the musculocutaneous nerve between the two parts of the coracobrachialis muscle was 19 cm (range, 15-24 cm) for the right and 20 cm (range, 15-25 cm) for the left arm.
CONCLUSIONS
If an accessory phrenic nerve is available, it presumably should be spared. Thus, in that case, a supraclavicular approach in combination with a nerve graft would probably be of advantage.
PubMed: 37763296
DOI: 10.3390/life13091892 -
Surgical Technology International Nov 2019The diaphragm is the primary muscle of respiration and its injury can cause diaphragm dysfunction and respiratory deficits. Respiratory compromise has historically been... (Review)
Review
The diaphragm is the primary muscle of respiration and its injury can cause diaphragm dysfunction and respiratory deficits. Respiratory compromise has historically been managed with mechanical ventilation, however, its use has also been shown to result in poor functional outcomes. Therefore, stimulation of the phrenic nerve, called diaphragm pacing, has been used to replace and/or delay the need for mechanical ventilation. This article will review the relevant literature on diaphragm pacing, discuss the physiology of diaphragm dysfunction in a variety of patient populations, and address whether diaphragm pacing is a valuable and effective option for treatment of respiratory failure.
Topics: Diaphragm; Electric Stimulation Therapy; Humans; Phrenic Nerve; Respiration, Artificial; Respiratory Insufficiency
PubMed: 31687777
DOI: No ID Found -
Chest May 2022Central sleep apnea (CSA) frequently coexists with heart failure and atrial fibrillation and contributes to cardiovascular disease progression and mortality. A... (Review)
Review
Central sleep apnea (CSA) frequently coexists with heart failure and atrial fibrillation and contributes to cardiovascular disease progression and mortality. A transvenous phrenic nerve stimulation (TPNS) system has been approved for the first time by the Food and Drug Administration for the treatment of CSA. This system, remedē System (Zoll Medical, Inc.), is implanted during a minimally invasive outpatient procedure and has shown a favorable safety and efficacy profile. Currently, patient access to this therapy remains limited by the small number of specialized centers in the United States and the absence of a standard coverage process by insurers. Although a period of evaluation by insurers is expected for new therapies in their early stages, the impact on patients is particularly severe given the already limited treatment options for CSA. Implantation and management of this novel therapy require the establishment of a specialized multidisciplinary program as part of a sleep medicine practice and support from health care systems and hospitals. Several centers in the United States have been successful in building sustainable TPNS programs offering this novel therapy to their patients by navigating the current reimbursement environment. In this article, we review the background and efficacy data of TPNS and briefly address relevant aspects of the clinical activities involved in a TPNS program. The article presents the status of coverage and reimbursement for this novel therapy. We also discuss the current approach to obtaining reimbursement from third-party payors during this transitional period of evaluation by Medicare and other insurers.
Topics: Aged; Electric Stimulation Therapy; Humans; Medicare; Phrenic Nerve; Sleep Apnea, Central; Treatment Outcome; United States
PubMed: 34808108
DOI: 10.1016/j.chest.2021.11.012 -
Biomedical Engineering Online Jan 2023Every year, more than 2.5 million critically ill patients in the ICU are dependent on mechanical ventilation. The positive pressure in the lungs generated by the...
BACKGROUND
Every year, more than 2.5 million critically ill patients in the ICU are dependent on mechanical ventilation. The positive pressure in the lungs generated by the ventilator keeps the diaphragm passive, which can lead to a loss of myofibers within a short time. To prevent ventilator-induced diaphragmatic dysfunction (VIDD), phrenic nerve stimulation may be used.
OBJECTIVE
The goal of this study is to show the feasibility of transesophageal phrenic nerve stimulation (TEPNS). We hypothesize that selective phrenic nerve stimulation can efficiently activate the diaphragm with reduced co-stimulations.
METHODS
An in vitro study in saline solution combined with anatomical findings was performed to investigate relevant stimulation parameters such as inter-electrode spacing, range to target site, or omnidirectional vs. sectioned electrodes. Subsequently, dedicated esophageal electrodes were inserted into a pig and single stimulation pulses were delivered simultaneously with mechanical ventilation. Various stimulation sites and response parameters such as transdiaphragmatic pressure or airway flow were analyzed to establish an appropriate stimulation setting.
RESULTS
Phrenic nerve stimulation with esophageal electrodes has been demonstrated. With a current amplitude of 40 mA, similar response figures of the diaphragm activation as compared to conventional stimulation with needle electrodes at 10mA were observed. Directed electrodes best aligned with the phrenic nerve resulted in up to 16.9 % higher amplitude at the target site in vitro and up to 6 cmH20 higher transdiaphragmatic pressure in vivo as compared to omnidirectional electrodes. The activation efficiency was more sensitive to the stimulation level inside the esophagus than to the inter-electrode spacing. Most effective and selective stimulation was achieved at the level of rib 1 using sectioned electrodes 40 mm apart.
CONCLUSION
Directed transesophageal phrenic nerve stimulation with single stimuli enabled diaphragm activation. In the future, this method might keep the diaphragm active during, and even support, artificial ventilation. Meanwhile, dedicated sectioned electrodes could be integrated into gastric feeding tubes.
Topics: Animals; Swine; Phrenic Nerve; Feasibility Studies; Diaphragm; Respiration, Artificial; Electrodes; Electric Stimulation
PubMed: 36717872
DOI: 10.1186/s12938-023-01071-5