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British Journal of Anaesthesia Mar 2011During subclavian vein catheterization, a potential, but rare, hazard is the phrenic nerve injury, which compromises respiratory function. We conducted a cadaver study...
BACKGROUND
During subclavian vein catheterization, a potential, but rare, hazard is the phrenic nerve injury, which compromises respiratory function. We conducted a cadaver study focused on the possible anatomical relationships between the subclavian vein and the phrenic nerve.
METHODS
Forty-two adult cadavers (84 heminecks) were dissected. Special attention was given to the topography of the phrenic nerve and subclavian vein.
RESULTS
In all but three cases (81 of 84), normal topography was present, that is, the nerve was posterior to the vein. In two cases, the phrenic nerve crossed anterior to the subclavian vein and in one case traversed the anterior wall of the subclavian vein.
CONCLUSIONS
Variants of the relationship of the subclavian vein and the phrenic nerve should be familiar to anaesthesiologists during subclavian vein cannulation in order to achieve successful vein approach without causing phrenic nerve palsy.
Topics: Aged; Aged, 80 and over; Catheterization, Central Venous; Female; Humans; Male; Phrenic Nerve; Subclavian Vein
PubMed: 21233111
DOI: 10.1093/bja/aeq373 -
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 -
Journal of Neurophysiology Sep 2021Plasticity is a hallmark of the respiratory neural control system. Phrenic long-term facilitation (pLTF) is one form of respiratory plasticity characterized by...
Plasticity is a hallmark of the respiratory neural control system. Phrenic long-term facilitation (pLTF) is one form of respiratory plasticity characterized by persistent increases in phrenic nerve activity following acute intermittent hypoxia (AIH). Although there is evidence that key steps in the cellular pathway giving rise to pLTF are localized within phrenic motor neurons (PMNs), the impact of AIH on the strength of breathing-related synaptic inputs to PMNs remains unclear. Furthermore, the functional impact of AIH is enhanced by repeated/daily exposure to AIH (dAIH). Here, we explored the effects of AIH versus 2 wk of dAIH preconditioning on spontaneous and evoked phrenic responses in anesthetized, paralyzed, and mechanically ventilated rats. Evoked phrenic potentials were elicited by respiratory cycle-triggered lateral funiculus stimulation at the C2 spinal level delivered before and 60 min post-AIH (or the equivalent in time controls). Charge-balanced biphasic pulses (100 μs/phase) of progressively increasing intensity (100-700 μA) were delivered during the inspiratory and expiratory phases of the respiratory cycle. Although robust pLTF (∼60% from baseline) was observed after a single exposure to moderate AIH (3 × 5 min; 5-min intervals), there was no effect on evoked phrenic responses, contrary to our initial hypothesis. However, in rats preconditioned with dAIH, baseline phrenic nerve activity and evoked responses were increased, suggesting that repeated exposure to AIH enhances functional synaptic strength when assessed using this technique. The impact of daily AIH preconditioning on synaptic inputs to PMNs raises interesting questions that require further exploration. Two weeks of daily acute intermittent hypoxia (dAIH) preconditioning enhanced stimulus-evoked phrenic responses to lateral funiculus stimulation (targeting respiratory bulbospinal projection to phrenic motor neurons). Furthermore, dAIH preconditioning enhanced baseline phrenic motor output responses to maximal chemoreflex activation in intact rats.
Topics: Animals; Evoked Potentials; Hypoxia; Male; Motor Neurons; Neuronal Plasticity; Phrenic Nerve; Rats; Rats, Sprague-Dawley
PubMed: 34260289
DOI: 10.1152/jn.00112.2021 -
Journal of Cancer Research and... Dec 2022This study aimed to analyze the cases of phrenic nerve injury caused by the percutaneous microwave ablation of lung tumors conducted at our center and to explore the...
OBJECTIVE
This study aimed to analyze the cases of phrenic nerve injury caused by the percutaneous microwave ablation of lung tumors conducted at our center and to explore the risk factors.
MATERIALS AND METHODS
The data of 455 patients who underwent the percutaneous microwave ablation of lung tumors at the Department of Interventional Radiology, First Affiliated Hospital of Fujian Medical University from July 2017 to October 2021, were retrospectively analyzed. The cases of phrenic nerve injury after the percutaneous ablation were reported to analyze the risk factors involved, such as the shortest distance between tumor margin and phrenic nerve, tumor size, and ablation energy. The groups were divided based on the shortest distance between the tumor edge and the phrenic nerve into group 1, d ≤ l cm; group 2, 1 < d ≤2 cm; and group 3, d >2 cm. Lesions with a distance ≤2 cm were compared in terms of tumor size and ablation energy.
RESULTS
Among the 455 patients included in this study, 348 had primary lung cancer, and 107 had oligometastatic cancer. A total of 579 lesions were detected, with maximum diameter of 1.27 ± 0.55 cm, and the ablation energy was 9,000 (4,800-72,000) J. Six patients developed phrenic nerve injury, with an incidence of 1.32%. For these six patients, the shortest distance from the lesion edge to the phrenic nerve was 0.75 ± 0.48 cm, and the ablation energy was 10,500 (8,400-34,650) J. There were statistically significant differences in phrenic nerve injury among groups 1, 2, and 3 (P < 0.05). In patients with a distance (d) ≤ 2 cm, there were no significant differences in tumor diameter and energy between the phrenic nerve injury group and the non-injury group (P = 0.80; P = 0.41). In five out of six patients, the diaphragm level completely recovered to the pre-procedure state, and the recovery time of the phrenic nerve was 9.60 ± 5.60 months. Another one was re-examined 11 months after the procedure, and the level of the diaphragm on the affected side had partially recovered.
CONCLUSIONS
Phrenic nerve injury is a rare but not negligible complication of thermal ablation and is more likely to occur in lesions with a distance ≤2 cm from the phrenic nerve.
Topics: Humans; Catheter Ablation; Phrenic Nerve; Retrospective Studies; Microwaves; Lung Neoplasms; Treatment Outcome
PubMed: 36647962
DOI: 10.4103/jcrt.jcrt_1254_22 -
Journal of Neurophysiology Jul 2019In aging Fischer 344 rats, phrenic motor neuron loss, neuromuscular junction abnormalities, and diaphragm muscle (DIAm) sarcopenia are present by 24 mo of age, with...
In aging Fischer 344 rats, phrenic motor neuron loss, neuromuscular junction abnormalities, and diaphragm muscle (DIAm) sarcopenia are present by 24 mo of age, with larger fast-twitch fatigue-intermediate (type FInt) and fast-twitch fatigable (type FF) motor units particularly vulnerable. We hypothesize that in old rats, DIAm neuromuscular transmission deficits are specific to type FInt and/or FF units. In phrenic nerve/DIAm preparations from rats at 6 and 24 mo of age, the phrenic nerve was supramaximally stimulated at 10, 40, or 75 Hz. Every 15 s, the DIAm was directly stimulated, and the difference in forces evoked by nerve and muscle stimulation was used to estimate neuromuscular transmission failure. Neuromuscular transmission failure in the DIAm was observed at each stimulation frequency. In the initial stimulus trains, the forces evoked by phrenic nerve stimulation at 40 and 75 Hz were significantly less than those evoked by direct muscle stimulation, and this difference was markedly greater in 24-mo-old rats. During repetitive nerve stimulation, neuromuscular transmission failure at 40 and 75 Hz worsened to a greater extent in 24-mo-old rats compared with younger animals. Because type IIx and/or IIb DIAm fibers (type FInt and/or FF motor units) display greater susceptibility to neuromuscular transmission failure at higher frequencies of stimulation, these data suggest that the age-related loss of larger phrenic motor neurons impacts nerve conduction to muscle at higher frequencies and may contribute to DIAm sarcopenia in old rats. Diaphragm muscle (DIAm) sarcopenia, phrenic motor neuron loss, and perturbations of neuromuscular junctions (NMJs) are well described in aged rodents and selectively affect FInt and FF motor units. Less attention has been paid to the motor unit-specific aspects of nerve-muscle conduction. In old rats, increased neuromuscular transmission failure occurred at stimulation frequencies where FInt and FF motor units exhibit conduction failures, along with decreased apposition of pre- and postsynaptic domains of DIAm NMJs of these units.
Topics: Aging; Animals; Diaphragm; Female; Male; Motor Neurons; Muscle Fatigue; Muscle Fibers, Fast-Twitch; Neuromuscular Junction; Phrenic Nerve; Rats; Rats, Inbred F344; Synaptic Potentials
PubMed: 31042426
DOI: 10.1152/jn.00061.2019 -
Respiratory Research Dec 2022Rapid magnetic stimulation (RMS) of the phrenic nerves may serve to attenuate diaphragm atrophy during mechanical ventilation. With different coil shapes and stimulation... (Clinical Trial)
Clinical Trial
Inspiratory response and side-effects to rapid bilateral magnetic phrenic nerve stimulation using differently shaped coils: implications for stimulation-assisted mechanical ventilation.
BACKGROUND
Rapid magnetic stimulation (RMS) of the phrenic nerves may serve to attenuate diaphragm atrophy during mechanical ventilation. With different coil shapes and stimulation location, inspiratory responses and side-effects may differ. This study aimed to compare the inspiratory and sensory responses of three different RMS-coils either used bilaterally on the neck or on the chest, and to determine if ventilation over 10 min can be achieved without muscle fatigue and coils overheating.
METHODS
Healthy participants underwent bilateral anterior 1-s RMS on the neck (RMS) (N = 14) with three different pairs of magnetic coils (parabolic, D-shape, butterfly) at 15, 20, 25 and 30 Hz stimulator-frequency and 20% stimulator-output with + 10% increments. The D-shape coil with individual optimal stimulation settings was then used to ventilate participants (N = 11) for up to 10 min. Anterior RMS on the chest (RMS) (N = 8) was conducted on an optional visit. Airflow was assessed via pneumotach and transdiaphragmatic pressure via oesophageal and gastric balloon catheters. Perception of air hunger, pain, discomfort and paresthesia were measured with a numerical scale.
RESULTS
Inspiration was induced via RMS in 86% of participants with all coils and via RMS in only one participant with the parabolic coil. All coils produced similar inspiratory and sensory responses during RMS with the butterfly coil needing higher stimulator-output, which resulted in significantly larger discomfort ratings at maximal inspiratory responses. Ten of 11 participants achieved 10 min of ventilation without decreases in minute ventilation (15.7 ± 4.6 L/min).
CONCLUSIONS
RMS was more effective than RMS and could temporarily ventilate humans seemingly without development of muscular fatigue. Trial registration This study was registered on clinicaltrials.gov (NCT04176744).
Topics: Humans; Diaphragm; Magnetic Phenomena; Muscle Fatigue; Phrenic Nerve; Respiration, Artificial
PubMed: 36528761
DOI: 10.1186/s12931-022-02251-y -
Postgraduate Medical Journal Apr 1998Measurement of respiratory muscle strength is useful in order to detect respiratory muscle weakness and to quantify its severity. In patients with severe respiratory... (Review)
Review
Measurement of respiratory muscle strength is useful in order to detect respiratory muscle weakness and to quantify its severity. In patients with severe respiratory muscle weakness, vital capacity is reduced but is a non-specific and relatively insensitive measure. Conventionally, inspiratory and expiratory muscle strength has been assessed by maximal inspiratory and expiratory mouth pressures sustained for 1 s (PImax and PEmax) during maximal static manoeuvre against a closed shutter. However, PImax and PEmax are volitional tests, and are poorly reproducible with an average coefficient of variation of 25%. The sniff manoeuvre is natural and probably easier to perform. Sniff pressure, and sniff transdiaphragmatic pressure are more reproducible and useful measure of diaphragmatic strength. Nevertheless, the sniff manoeuvre is also volition-dependent, and submaximal efforts are most likely to occur in patients who are ill or breathless. Non-volitional tests include measurements of twitch oesophageal, gastric and transdiaphragmatic pressure during bilateral electrical and magnetic phrenic nerve stimulation. Electrical phrenic nerve stimulation is technically difficult and is also uncomfortable and painful. Magnetic phrenic nerve stimulation is less painful and transdiaphragmatic pressure is reproducible in normal subjects. It is a relatively easy test that has the potential to become a widely adopted method for the assessment of diaphragm strength. The development of a technique to measure diaphragmatic sound (phonomyogram) during magnetic phrenic nerve stimulation opens the way for noninvasive assessment of diaphragmatic function.
Topics: Electric Stimulation; Humans; Muscle Weakness; Neuromuscular Diseases; Phrenic Nerve; Respiratory Function Tests; Respiratory Muscles
PubMed: 9683973
DOI: 10.1136/pgmj.74.870.208 -
Physiological Research 2016This study was undertaken to determine pattern sensitivity of phrenic nerve plasticity in respect to different respiratory challenges. We compared long-term effects of...
This study was undertaken to determine pattern sensitivity of phrenic nerve plasticity in respect to different respiratory challenges. We compared long-term effects of intermittent and continuous hypercapnic and hypoxic stimuli, and combined intermittent hypercapnia and hypoxia on phrenic nerve plasticity. Adult, male, urethane-anesthetized, vagotomized, paralyzed, mechanically ventilated Sprague-Dawley rats were exposed to: acute intermittent hypercapnia (AIHc or AIHc(O2)), acute intermittent hypoxia (AIH), combined intermittent hypercapnia and hypoxia (AIHcH), continuous hypercapnia (CHc), or continuous hypoxia (CH). Peak phrenic nerve activity (pPNA) and burst frequency were analyzed during baseline (T0), hypercapnia or hypoxia exposures, at 15, 30, and 60 min (T60) after the end of the stimulus. Exposure to acute intermittent hypercapnia elicited decrease of phrenic nerve frequency from 44.25+/-4.06 at T0 to 35.29+/-5.21 at T60, (P=0.038, AIHc) and from 45.5+/-2.62 to 37.17+/-3.68 breaths/min (P=0.049, AIHc(O2)), i.e. frequency phrenic long term depression was induced. Exposure to AIH elicited increase of pPNA at T60 by 141.0+/-28.2 % compared to baseline (P=0.015), i.e. phrenic long-term facilitation was induced. Exposure to AIHcH, CHc, or CH protocols failed to induce long-term plasticity of the phrenic nerve. Thus, we conclude that intermittency of the hypercapnic or hypoxic stimuli is needed to evoke phrenic nerve plasticity.
Topics: Animals; Hypercapnia; Hypoxia; Long-Term Potentiation; Male; Neuronal Plasticity; Periodicity; Phrenic Nerve; Rats; Rats, Sprague-Dawley
PubMed: 26596313
DOI: 10.33549/physiolres.933012 -
Experimental Physiology Jan 2007The respiratory system expresses multiple forms of plasticity, defined as alterations in the breathing pattern that persist or develop after a stimulus. Stimulation of... (Comparative Study)
Comparative Study
The respiratory system expresses multiple forms of plasticity, defined as alterations in the breathing pattern that persist or develop after a stimulus. Stimulation of breathing with intermittent hypoxia (IH) elicits long-term facilitation (LTF), a type of plasticity in which respiratory motor activity progressively increases in anaesthetized animals, even after the stimuli have ceased and blood gases have normalized. It is unknown whether the sympathetic nervous system similarly expresses IH-induced plasticity, but we predicted that IH would evoke LTF in sympathetic nerve activity (SNA) because respiratory and sympathetic control systems are coupled. To test this idea, we recorded splanchnic (sSNA) and phrenic nerve activities (PNA) in equithesin-anaesthetized rats. Animals were exposed to 10 45 s episodes of 8% O(2)-92% N(2), separated by 5 min intervals of 100% O(2), and recordings were continued for 60 min following the last hypoxic exposure. Cycle-triggered averages of integrated PNA and sSNA from periods preceding, and 5 and 60 min following the hypoxic stimuli were compared. Intermittent hypoxia significantly increased both sSNA and PNA. Treatment with methysergide (3 mg kg(-1), i.v.) 20 min before the intermittent hypoxic exposures prevented the increases in integrated PNA and sSNA 60 min after IH, indicating a role of serotonergic pathways in this form of plasticity. No increases in PNA and sSNA occurred at comparable times (60 and 120 min) in rats not exposed to hypoxia. The increased sSNA was not simply tonic, but was correlated with respiratory bursts, and occurred predominantly during the first half of expiration. These findings support the hypothesis that sympathorespiratory coupling may underlie the sustained increase in SNA associated with the IH that occurs during sleep apnoea.
Topics: Acute Disease; Animals; Disease Models, Animal; Hypoxia; Long-Term Potentiation; Male; Methysergide; Neuronal Plasticity; Phrenic Nerve; Rats; Rats, Sprague-Dawley; Respiratory Mechanics; Respiratory Muscles; Respiratory System; Serotonin; Serotonin Antagonists; Sleep Apnea Syndromes; Splanchnic Nerves; Sympathetic Nervous System; Time Factors
PubMed: 17138622
DOI: 10.1113/expphysiol.2006.035758 -
The Journal of International Medical... Dec 2023Persistent hiccups that occur after abdominal surgery seriously affect postoperative rehabilitation. Phrenic nerve block therapy has been recommended after failure of... (Review)
Review
Persistent hiccups that occur after abdominal surgery seriously affect postoperative rehabilitation. Phrenic nerve block therapy has been recommended after failure of medication or physical maneuvers. However, the phrenic nerve is often difficult to accurately identify because of its small diameter and anatomic variations. We combined ultrasound with the use of a nerve stimulator to quickly and accurately identify and block the phrenic nerve in a patient with postoperative persistent hiccups. The ongoing hiccups were immediately terminated with no adverse effects. The patient reported no recurrence during the 2-week follow-up period. We conclude that the combined use of real-time ultrasound guidance and a nerve stimulator for singular phrenic nerve block might be an effective intervention for terminating postoperative persistent hiccups, although further studies are needed to evaluate the safety and efficacy of this technique. The findings in this case suggest a potential clinical application for this technique in managing persistent hiccups, thereby contributing to improved patient care and outcomes.
Topics: Humans; Hiccup; Phrenic Nerve; Ultrasonography; Nerve Block
PubMed: 38041831
DOI: 10.1177/03000605231216616