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Anesthesiology Research and Practice 2023Peripheral nerve blocks are an increasingly common method of providing postoperative analgesia for shoulder surgeries. However, the standard technique, the interscalene... (Review)
Review
Peripheral nerve blocks are an increasingly common method of providing postoperative analgesia for shoulder surgeries. However, the standard technique, the interscalene block (ISB), inevitably causes hemidiaphragmatic paresis (HDP), secondary to phrenic nerve palsy. This can cause morbidity in patients with preexisting respiratory compromise, prompting investigation into alternative "phrenic-sparing" nerve blocks. The aim of this review was to give an overview of these blocks and critically evaluate the current literature to determine if any are suitable replacements for ISB. The incidence of HDP and analgesic efficacy were considered. We queried four electronic databases and one register. Twenty-eight original articles were selected for review. The use of ultrasound guidance, lower volumes of local anaesthetic (LA), and injection 4 mm outside the brachial plexus fascia reduced HDP incidence for the ISB; however, no single modification did so sufficiently. While the anterior suprascapular nerve block (SSNB) showed comparable analgesic effects to the ISB, HDP prevalence was also high. The posterior SSNB produced consistently low HDP incidences but also inferior analgesia to ISB, except when combined with an infraclavicular brachial plexus block. The superior trunk block (STB) provided equivalent analgesia to the ISB while reducing HDP incidence, but not significantly. Lower LA volumes consistently led to lower HDP incidence across all blocks, likely due to a reduced ability to spread to the phrenic nerve. Further investigation into the minimum effective volumes of the extrafascial ISB, anterior SSNB, STB, and combined posterior SSNB with infraclavicular block is warranted to determine if any of these blocks can successfully balance HDP prevention with analgesic efficacy.
PubMed: 37727810
DOI: 10.1155/2023/9962595 -
Respiratory Physiology & Neurobiology Dec 2022HF-SCS is a novel technique of inspiratory muscle activation which results in coincident activation of the diaphragm and inspiratory intercostal muscles via spinal cord...
OBJECTIVE
HF-SCS is a novel technique of inspiratory muscle activation which results in coincident activation of the diaphragm and inspiratory intercostal muscles via spinal cord pathways and has the potential to provide respiratory support in ventilator dependent persons with spinal cord injury. The purpose of the present study was to examine the phrenic-to-intercostal reflex during HF-SCS.
METHODS
In 5 anesthetized and C2 spinalized dogs, electrical stimulation was applied via a stimulating electrode located on the ventral surface of the upper thoracic spinal cord at the T2 level. Fine wire recording electrodes were used to assess single motor unit (SMU) activity of the left and right external intercostal muscles (EI) in the 3rd interspace before and after sequential left and right phrenicotomy.
RESULTS
Mean control peak firing frequency of the right EI and left EI was 11.4 ± 0.3 Hz and 10.6 ± 0.3 Hz respectively. Following unilateral right phrenic nerve section, mean SMU peak firing frequency of right EI (ipsilateral to the section) was significantly greater when compared to control (15.9 ± 0.5 Hz vs 11.4 ± 0.3 Hz; p = 0.01). Mean SMU peak firing frequency of the contralateral left EI remained unchanged (10.2 ± 0.3 Hz vs 10.6 ± 0.3 Hz, p = 0.40). Subsequent, section of the left phrenic nerve resulted in significantly higher mean SMU peak firing frequency of the left EI (16.2 ± 0.5 Hz vs 10.2 ± 0.3 Hz) when compared to before section p = 0.01). Contralateral, right EI peak firing frequency was not different if compared to before left phrenic nerve section (16.9 ± 0.4 Hz vs. 15.9 ± 0.5 Hz; p = 0.14).
CONCLUSION
This study demonstrates that during HF-SCS: 1) unilateral diaphragmatic afferents reflexly inhibit motor activity to the ipsilateral EI muscles, 2) the neural circuitry mediating the phrenic-to-intercostal reflex is preserved at a spinal level and does not require supraspinal input and 3) unilateral compensatory increases were observed in EI muscle activation following ipsilateral diaphragm paralysis.
Topics: Animals; Diaphragm; Dogs; Electric Stimulation; Intercostal Muscles; Phrenic Nerve; Reflex; Spinal Cord; Spinal Cord Injuries; Spinal Cord Stimulation
PubMed: 36064141
DOI: 10.1016/j.resp.2022.103962 -
Journal of Cardiothoracic and Vascular... Aug 2022This meta-analysis was aimed at investigating the effectiveness and safety of phrenic nerve infiltration (PNI) against ipsilateral shoulder pain (ISP) after thoracic... (Meta-Analysis)
Meta-Analysis Review
Effect of Intraoperative Phrenic Nerve Infiltration on Postoperative Ipsilateral Shoulder Pain After Thoracic Surgeries: A Systematic Review and Meta-Analysis of Randomized Controlled Studies.
OBJECTIVES
This meta-analysis was aimed at investigating the effectiveness and safety of phrenic nerve infiltration (PNI) against ipsilateral shoulder pain (ISP) after thoracic surgery.
DESIGN
A systematic review and meta-analysis of randomized controlled trials (RCTs).
SETTING
Operating room.
PARTICIPANTS
Patients undergoing thoracic surgery.
INTERVENTIONS
PNI.
MEASUREMENTS AND MAIN RESULTS
MEDLINE, Cochrane Library, and EMBASE databases were searched from inception through December 2021. The primary outcome was the overall incidence of ISP, with secondary outcomes including incidence and severity of ISP at postoperative 6, 24, and 48 hours. Six RCTs involving 482 patients undergoing thoracic surgery were included. Pooled results found a significantly lower incidence of overall ISP in patients with PNI (ie, 23.6%) compared to those without (ie, 53.2%; risk ratio: 0.46, 95% confidence interval: 0.34-0.61; I = 19%; 6 RCTs; n = 474; certainty of evidence = high). At postoperative 6, 24, and 48 hours, there was also a significantly lower incidence of ISP in the PNI group than in the control group (certainty of evidence for all outcomes = high). Besides, the severity of ISP was lower in the PNI group at 6 (certainty of evidence = moderate) and 24 hours (certainty of evidence = high), with insufficient data for analysis at 48 hours because of only 1 trial.
CONCLUSION
This meta-analysis showed that PNI not only reduced the incidence but also improved the severity of ipsilateral shoulder pain after thoracic surgery with a prophylactic effect lasting up to 48 hours. The limited number of included studies warrants further research to support these findings.
Topics: Humans; Pain, Postoperative; Phrenic Nerve; Postoperative Period; Shoulder Pain; Thoracic Surgical Procedures
PubMed: 35570082
DOI: 10.1053/j.jvca.2022.04.016 -
Practical Radiation Oncology 2023Incremental use of high-dose radiation therapy (RT) with SABR in thoracic tumors has led to identification of many unusual toxicities (chest wall pain, rib fractures,...
Incremental use of high-dose radiation therapy (RT) with SABR in thoracic tumors has led to identification of many unusual toxicities (chest wall pain, rib fractures, vascular perforation, brachial plexopathy) and consequently additional organs at risk (OARs; chest wall, ribs, bronchial wall, carotid artery, brachial plexus). Phrenic nerve is another structure that may be affected at any point during its long course from origin until end, although symptomatic toxicities have been reported rarely in the setting of reirradiation, large-volume irradiation such as mantle field, or SABR. We undertook a prospective study to describe the delineation of phrenic nerve course on RT planning computed tomography scan as an OAR. An anonymized RT planning computed tomography scan of neck and thorax (1.5-mm slice thickness, intravenous contrast) was used for the study. Radiology textbooks and publications were reviewed, and the course was delineated with the help of 2 radiologists and 6 radiation oncologists well versed with thoracic radiologic anatomy. A step-by-step description in the form of a pictorial essay is given. The adjacent structures including cervical vertebrae, cervical and mediastinal vessels, lungs, heart, and so on were identified, and the course of phrenic nerve on either side is described in relation to these structures. Delineation of the phrenic nerve as an OAR is challenging but feasible. We recommend routine delineation of the phrenic nerve as an OAR during thoracic RT. Although specific dose constraints are not known yet, unnecessary dose to the same during RT planning should be minimized.
Topics: Humans; Phrenic Nerve; Prospective Studies; Lung Neoplasms; Lung; Thorax
PubMed: 35977668
DOI: 10.1016/j.prro.2022.08.002 -
Heart Rhythm Dec 2020Central sleep apnea is common in heart failure patients. Transvenous phrenic nerve stimulation (TPNS) requires placing a lead to stimulate the phrenic nerve and activate...
BACKGROUND
Central sleep apnea is common in heart failure patients. Transvenous phrenic nerve stimulation (TPNS) requires placing a lead to stimulate the phrenic nerve and activate the diaphragm. Data are lacking concerning the safety and efficacy of TPNS in patients with concomitant cardiovascular implantable electronic devices (CIEDs).
OBJECTIVE
To report the safety and efficacy of TPNS in patients with concomitant CIEDs.
METHODS
In the remedē System Pivotal Trial, 151 patients underwent TPNS device implant. This analysis compared patients with concomitant CIEDs to those without with respect to safety, implant metrics, and efficacy of TPNS. Safety was assessed using incidence of adverse events and device-device interactions. A detailed interaction protocol was followed. Implant metrics included overall TPNS implantation success. Efficacy endpoints included changes in the apnea-hypopnea index (AHI) and quality of life.
RESULTS
Of 151 patients, 64 (42%) had a concomitant CIED. There were no significant differences between the groups with respect to safety. There were 4 CIED oversensing events in 3 patients leading to 1 inappropriate defibrillator shock and delivery of antitachycardia pacing. There was no difference in efficacy between the CIED and non-CIED subgroups receiving TPNS, with both having similar percentages of patients who achieved ≥50% reduction in AHI and quality-of-life improvement.
CONCLUSION
Concomitant CIED and TPNS therapy is safe. The presence of a concomitant CIED did not seem to impact implant metrics, implantation success, and TPNS efficacy. A detailed interaction protocol should be followed to minimize the incidence of device-device interaction.
Topics: Aged; Catheterization, Peripheral; Diaphragm; Electric Stimulation Therapy; Female; Follow-Up Studies; Heart Failure; Humans; Male; Middle Aged; Phrenic Nerve; Prospective Studies; Sleep Apnea, Central; Treatment Outcome
PubMed: 32619739
DOI: 10.1016/j.hrthm.2020.06.023 -
Journal of Neurophysiology Dec 2021Phrenic afferents project to brainstem areas responsible for cardiorespiratory control and the mid-cervical spinal cord containing the phrenic motor nucleus. Our purpose...
Phrenic afferents project to brainstem areas responsible for cardiorespiratory control and the mid-cervical spinal cord containing the phrenic motor nucleus. Our purpose was to quantify the impact of small- and large-diameter phrenic afferent activation on phrenic motor output. Anesthetized and ventilated rats received unilateral phrenic nerve stimulation while contralateral phrenic motor output and blood pressure were recorded. Twelve currents of 40-Hz inspiratory-triggered stimulation were delivered (20 s on, 5 min off) to establish current response curves. Stimulation pulse width was varied to preferentially activate large-diameter phrenic afferents (narrow pulse width) and recruit small-diameter fibers (wide pulse width). Contralateral phrenic amplitude was elevated immediately poststimulation at currents above 35 µA for wide and 70 µA for narrow pulse stimulation when compared with animals not receiving stimulation (time controls). Wide pulse width stimulation also increased phrenic burst frequency at currents ≥35 µA, caused a transient decrease in mean arterial blood pressure at currents ≥50 µA, and resulted in a small change in heart rate at 300 µA. Unilateral dorsal rhizotomy attenuated stimulation-induced cardiorespiratory responses indicating that phrenic afferent activation is required. Additional analyses compared phrenic motor amplitude with output before stimulation and showed that episodic activation of phrenic afferents with narrow pulse stimulation can induce short-term plasticity. We conclude that the activation of phrenic afferents ) enhances contralateral phrenic motor amplitude when large-diameter afferents are activated, and ) when small-diameter fibers are recruited, the amplitude response is associated with changes in burst frequency and cardiovascular parameters. Acute, inspiratory-triggered stimulation of phrenic afferents increases contralateral phrenic motor amplitude in adult rats. When small-diameter afferents are recruited, the amplitude response is accompanied by an increase in phrenic burst frequency, a transient decrease in mean arterial blood pressure, and a slight increase in heart rate. Repeated episodes of large-diameter phrenic afferent activation may also be capable of inducing short-term plasticity.
Topics: Afferent Pathways; Animals; Arterial Pressure; Blood Gas Analysis; Electrophysiological Phenomena; Female; Heart Rate; Hemodynamics; Inhalation; Male; Neuronal Plasticity; Neurons, Afferent; Phrenic Nerve; Rats; Rats, Sprague-Dawley
PubMed: 34788165
DOI: 10.1152/jn.00433.2021 -
Muscle & Nerve Nov 2020
Topics: Healthy Volunteers; Humans; Neural Conduction; Phrenic Nerve
PubMed: 32841402
DOI: 10.1002/mus.27050 -
Amyotrophic Lateral Sclerosis &... 2021: Respiratory tests are fundamental for monitoring respiratory function in ALS, and essential in clinical trials. Slow vital capacity (SVC) was canceled in some...
: Respiratory tests are fundamental for monitoring respiratory function in ALS, and essential in clinical trials. Slow vital capacity (SVC) was canceled in some countries to prevent COVID-19 transmission. We aimed to test phrenic nerve motor responses as an option to SVC in clinical trials. : Patients followed-up in our unit were selected respecting inclusion criteria used elsewhere: possible/probable/definite disease; onset-age 18-80years; disease duration from disease duration ≤24months; body mass index (BMI)>20kg/m; respiratory subscore of the revised ALS functional rating scale (ALSFRS-R)≥11; upright SVC ≥ 70%. We added normal phrenic responses (meanPhrenAmpl, ≥0.4mV). All patients were on riluzole. SVC and meanPhrenAmpl were recorded at study entry (T0) and 24 weeks later (T1). Decays were determined. Sample size was calculated for a treatment effect of 30% on the decay rate. : We included 317 ALS patients (191 males, 225 spinal-onset), mean onset-age 59.9 ± 10.7 (31-80)years, mean onset BMI 25.48 ± 3.2 (20.1-35)kg/m, mean disease duration 10.5 ± 5.6 (1-24)months, mean ALSFRS-R 41.54 ± 4.3 (22-47) and respiratory subscore 11.83 ± 0.38 (11-12). MeanPhrenAmpl and SVC were weakly but significantly correlated at T0 and T1. At T1, MeanPhrenAmpl decayed 16.94 ± 16.45% and SVC 13.5 ± 16.86%. For the proposed drug effect, 174 and 272 patients would be needed to recruit using respectively meanPhrenAmpl and SVC decline as the primary outcome measurement (accepting no dropouts). : Contrary to SVC, meanPhrenAmpl is non-volitional and not associated with aerosolization risk. Lower recruitment number (98 patients less) would be needed, translating shorter inclusion period, trial length and costs, and probable lower missed data rate. MeanPhrenAmp is an alternative test in ALS clinical trials.
Topics: Adolescent; Adult; Aged; Aged, 80 and over; Amyotrophic Lateral Sclerosis; COVID-19; Humans; Male; Middle Aged; Phrenic Nerve; SARS-CoV-2; Vital Capacity; Young Adult
PubMed: 33683161
DOI: 10.1080/21678421.2021.1895842 -
Respiratory Care May 2023Mechanical ventilation is widely used in ICU patients as a lifesaving intervention. Diaphragmatic atrophy and thinning occur from lack of contractions of the diaphragm...
BACKGROUND
Mechanical ventilation is widely used in ICU patients as a lifesaving intervention. Diaphragmatic atrophy and thinning occur from lack of contractions of the diaphragm during mechanical ventilation. It may prolong weaning and increase the risk of respiratory complications. Noninvasive electromagnetic stimulation of the phrenic nerves may ameliorate the atrophy seen with ventilation. The objective of this study was to show that noninvasive repetitive electromagnetic stimulation is safe, feasible, and effective to stimulate the phrenic nerves in both awake individuals and anesthetized patients.
METHODS
A single-center study with 10 subjects overall, 5 awake volunteers and 5 anesthetized subjects. We used a prototype electromagnetic, noninvasive, simultaneous bilateral phrenic nerve stimulation device in both groups. In the awake volunteers, we assessed time-to-first capture of the phrenic nerves and safety measures, such as pain, discomfort, dental paresthesia, and skin irritation. In the anesthetized subjects, time-to-first capture as well as tidal volumes and airway pressures at 20%, 30%, and 40% stimulation intensity were assessed.
RESULTS
Diaphragmatic capture was achieved in all the subjects within a median (range) of 1 min (1 min to 9 min 21 s) for the awake subjects and 30 s (20 s to 1 min 15 s) for the anesthetized subjects. There were no adverse or severe adverse events in either group, nor any dental paresthesia, skin irritation, or subjective pain in the stimulated area. Tidal volumes increased in all the subjects in response to simultaneous bilateral phrenic nerve stimulation and increased gradually with increasing stimulation intensity. Airway pressures corresponded to spontaneous breathing of ∼2 cm HO.
CONCLUSIONS
Noninvasive phrenic nerve stimulation can be safely performed in awake and anesthetized individuals. It was feasible and effective in stimulating the diaphragm by induction of physiologic and scalable tidal volumes with minimum positive airway pressures.
Topics: Humans; Phrenic Nerve; Feasibility Studies; Paresthesia; Respiration, Artificial; Diaphragm; Pain
PubMed: 36878642
DOI: 10.4187/respcare.10568 -
The Journal of Heart and Lung... Jan 2022Phrenic nerve injury (PNI) is a complication of lung transplantation related to the surgical procedure and associated with increased morbidity. However, the incidence...
BACKGROUND
Phrenic nerve injury (PNI) is a complication of lung transplantation related to the surgical procedure and associated with increased morbidity. However, the incidence and risk factors, specifically regarding surgical techniques, have not been adequately studied.
METHODS
We conducted a prospective single-center study over 4-years, in recipients of lung transplantation with a normal pretransplant phrenic nerve conduction study (PNCS). Diaphragm ultrasound and PNCS were performed in the first 21 postoperative days and PNI was defined when both tests were abnormal. Patients were followed up until hospital discharge. The association between transplant characteristics and PNI was analyzed by using logistic regression models.
RESULTS
Two hundred eleven lung grafts implanted in 127 patients were included in the study. After lung transplantation, PNI was diagnosed in 43.3% of the subjects and 29% of the operated hemithorax. Regression logistic model showed that the variables related to PNI were female gender (p = 0.02), bilateral lung transplantation (BLT) (p = 0.001), right lung graft (p = 0.003), clamshell incision (p = 0.01), mediastinal adhesions (p = 0.002), longer operative time (p = 0.003), intraoperative extracorporeal support (p = 0.02), and blood transfusion (p = 0.003). Conversely, age >61 years (p = 0.008) and higher thoracic diameter (p = 0.04) were protective factors. The use of electrocautery, cardiac mechanical retractors, and diaphragmatic traction was not associated with PNI. Morbidity was increased without any difference in mortality.
CONCLUSIONS
PNI is a frequent complication after lung transplantation, associated with higher morbidity. Mainly risk factors were age, BLT, female gender, and variables related to surgical difficulties. Lung graft in the right hemithorax and mediastinal adhesiolysis were the most relevant technical variables.
Topics: Female; Humans; Incidence; Intraoperative Complications; Lung Transplantation; Male; Middle Aged; Phrenic Nerve; Prospective Studies; Risk Factors
PubMed: 34756781
DOI: 10.1016/j.healun.2021.09.013