Respiratory Muscle Activity Research Articles

Respiratory muscle activity after spontaneous, neostigmine- or sugammadex-enhanced recovery of neuromuscular blockade: a double blind prospective randomized controlled trial

BackgroundThe use of neostigmine after neuromuscular blockade (NMB) has been associated with postoperative respiratory complications. In previous studies, we found lower diaphragmatic activity after neostigmine reversal of NMB, compared to sugammadex. It is still unclear whether the adequate use of neostigmine guarantees normal respiratory muscle function after NMB. In this study, we wanted to assess the effect of commonly used degrees of NMB and their possible reversal strategies on respiratory muscle activity after the return of normal neuromuscular transmission.MethodsThis is a randomized, controlled, parallel-group, single-centre, double-blind study in patients scheduled for intracranial surgery at a tertiary academic hospital in Belgium. All participants received target controlled propofol/remifentanil anesthesia and were randomized into one of five groups, receiving either a shallow NMB with no reversal (shallow/saline), a shallow NMB with sugammadex reversal (shallow/sugammadex), a moderate NMB with neostigmine reversal (moderate/neostigmine), a moderate NMB with sugammadex reversal (moderate/sugammadex), or a deep NMB with sugammadex reversal (deep/sugammadex). Primary and secondary outcome parameters were diaphragm and intercostal electromyographic (EMG) activity at the moment of resumed spontaneous breathing activity, defined as a maximal interval of 10 min after the first spontaneous breath.ResultsFor the five groups, a total of 55 patients could be included in the final analysis. Median time of spontaneous breathing analyzed was 5 min (IQR 3–9.5 min). Both the moderate/sugammadex and the moderate/neostigmine groups had lower levels of diaphragm EMG compared to the shallow/sugammadex group. The moderate/neostigmine group had lower levels of intercostal EMG activity compared to the shallow/saline group.ConclusionsIn this study, the depth of neuromuscular blockade and type of reversal strategy impacts respiratory muscle activity at the moment of resumed spontaneous breathing and recovery of neuromuscular blockade. Both groups that received moderate NMB had lower levels of diaphragm EMG, compared to the shallow NMB group with sugammadex reversal. Compared to the shallow NMB group with no reversal, the moderate NMB with neostigmine reversal group had lower intercostal EMG activity.Trial registrationClinicaltrials.gov NCT01962298 on October 9, 2013 and EudraCT 2013–001926-25 on October 10, 2013.

Circulating irisin levels in newly diagnosed obstructive sleep apnea patients

Introduction: Obstructive sleep apnea syndrome (OSAS) is commonly associated with obesity, insulin resistance, metabolic syndrome, hypertension, and coronary artery disease. Irisin is a newly identified myokine and its serum concentration was found to be correlated with cardiac troponin and creatin kinase-MB in acute myocardial infarction patients. Furthermore, irisin levels were positively associated with endothelium-dependent vasodilation in type 2 diabetic patients. Aim: In this study, we aimed to investigate serum irisin level in the newly diagnosed OSAS patients. Materials and Methods: After obtaining ethical approval, 32 OSAS patients were included. All patients gave written informed consent. Diagnosis of OSAS was verified by an overnight polysomnography (PSG) and made by an apnea hypopnea index equal to or higher than 5 . Venous blood samples were collected in the morning between 08.00 – 10.00 after PSG (n=25) or after one-night CPAP treatment (n=7). Serum irisin concentrations were studied by ELISA. Results and Conclusion: Serum irisin concentrations were significantly higher in newly diagnosed OSAS group than in OSAS group after one night of CPAP treatment ( 199.7±42.4 vs 159.7±18.3 ng/mL respectively; p<0.01). These results suggest that increased serum irisin levels can be reduced by CPAP treatment and elevated serum irisin levels may be due to increased respiratory muscle activity and body temperature .

Respiratory and Submental Muscles Activity During Inspiration and Expiration in Obstructive Sleep Apnea Syndrome

Respiratory and Submental Muscles Activity During Inspiration and Expiration in Obstructive Sleep Apnea Syndrome

Respiratory muscle activation and action during voluntary cough in healthy humans

Cough is a defensive airway reflex consisting of a modified respiratory act which involves the sequential activation of several laryngeal and respiratory muscles. The contraction of the latter results in thoraco-abdominal volume variations in order to provide enough amount of air available, the operating volume (OV), to be expelled. Because both posture and OV could influence muscular activation and thoraco-abdominal displacements during voluntary cough, we aimed to verify if and how they play a role during inspiratory (ICP) and expiratory (ECP) cough phases, in terms of flow, volumes and surface electromyography activity (sEMG). In 10 healthy subjects, we measured sEMG of 7 muscles (scalene, sternocleidomastoid, parasternal, intercostal, diaphragm (assessed at the 8th intercostal space), external abdominal oblique and rectus abdominis) in supine and seated position during cough maneuvers performed at 4 different OV measured by opto-electronic plethismography: total lung capacity (TLC), functional residual capacity and two intermediate volumes. The amplitude of sEMG signals tended to be maximal at TLC (p < 0.005) during ICP in the neck and parasternal muscles and during ECP in abdominal muscles. Postures slightly affected only sEMG of the thoracic muscles. sEMG data were similar (p > 0.05) in the other OV, but cough peak flow increased with OV. Thoraco-abdominal volume variations during cough were unaffected by posture and OV as well, being predominantly thoracic (supine: 60 and 64%; seated: 68 and 69%, respectively during ICP and ECP).Our results suggest that voluntary cough OV or posture do not have an important effect on voluntary cough that seems more likely to be resulting from a motor mechanism that activates a synergetic antagonistic contraction of inspiratory and expiratory muscles leading to a specific thoraco-abdominal pattern, in which the rib cage is the predominant.

The Thermal Sensitivity of Purinergic Modulation of Contractile Activity of Locomotor and Respiratory Muscles in Mice

Abstract—We have previously demonstrated that hypothermia significantly modulates the effect of ATP on the contractile activities of various types of rodent locomotor muscles. The aim of this study was to compare the effects of ATP on contraction of mouse locomotor (m. soleus) and respiratory (m. Diafragma) muscles at normal and low temperatures. It has been found that a decrease in the ambient temperature to 22°C is associated with a decrease in the force of muscle contraction (m. Diafragma) induced by electrical stimulation and carbachol, as well as with an increase in the contractile force of m. soleus. The potentiating effects of ATP in these muscles are preserved even in response to temperature reduction, but they are enhanced only in carbachol-induced contractions, thus indicating a postsynaptic localization of a thermal sensitive element in purine modulation. The characteristic features of ATP release modulation with the predominant postsynaptic thermal sensitive link in different motor units in hypothermia in mice may underlie the adaptive mechanisms of this small rodent.

The Effects of Sitting in a Crossed Legs Posture on the Vertebral Angle, Chest Wall Mobility, Pulmonary Function, and Respiratory Muscle Activity: A Preliminary Study

The Effects of Sitting in a Crossed Legs Posture on the Vertebral Angle, Chest Wall Mobility, Pulmonary Function, and Respiratory Muscle Activity: A Preliminary Study

Acute Effects of Inspiratory Loads and Interfaces on Breathing Pattern and Activity of Respiratory Muscles in Healthy Subjects.

ObjectivesThe aim of this study was to evaluate the acute effects of different inspiratory loads and different interfaces on the breathing pattern and activity of the respiratory muscles.MethodsTwenty healthy adults were recruited and assigned to two groups (20 and 40% of the Maximal Inspiratory Pressure) by way of randomized crossover allocation. Subjects were evaluated during quiet breathing, breathing against inspiratory load, and recovery. The measurements were repeated using two different interfaces (nasal and oral). Chest wall volumes and respiratory muscle activity were assessed with optoelectronic plethysmography and surface electromyography, respectively.ResultsDuring the application of inspiratory load, significant changes were observed in the respiratory rate (p < 0.04), inspiratory time (p < 0.02), minute ventilation (p < 0.04), tidal volume (p < 0.01), end-inspiratory volume (p < 0.04), end-expiratory volume (p < 0.03), and in the activity of the scalene, sternocleiomastoid, and parasternal portion of the intercostal muscles (RMS values, p < 0.01) when compared to quiet breathing, regardless of the load level or the interface applied. Inspiratory load application yielded significant differences between using nasal and oral interfaces with an increase in the tidal volume (p < 0.01), end-inspiratory volume (p < 0.01), and electrical activity of the scalene and sternocleiomastoid muscles (p < 0.01) seen with using the nasal interface.ConclusionThe addition of an inspiratory load has a significant effect on the breathing pattern and respiratory muscle electrical activity, and the effects are greater when the nasal interface is applied.

V2a Neurons Constrain Extradiaphragmatic Respiratory Muscle Activity at Rest.

Breathing requires precise control of respiratory muscles to ensure adequate ventilation. Neurons within discrete regions of the brainstem produce oscillatory activity to control the frequency of breathing. Less is understood about how spinal and pontomedullary networks modulate the activity of respiratory motor neurons to produce different patterns of activity during different behaviors (i.e., during exercise, coughing, swallowing, vocalizing, or at rest) or following disease or injury. Here, we use a chemogenetic approach to inhibit the activity of glutamatergic V2a neurons in the brainstem and spinal cord of neonatal and adult mice to assess their potential roles in respiratory rhythm generation and patterning respiratory muscle activity. Using whole-body plethysmography (WBP), we show that V2a neuron function is required in neonatal mice to maintain the frequency and regularity of respiratory rhythm. However, silencing V2a neurons in adult mice increases respiratory frequency and ventilation, without affecting regularity. Thus, the excitatory drive provided by V2a neurons is less critical for respiratory rhythm generation in adult compared to neonatal mice. In addition, we used simultaneous EMG recordings of the diaphragm and extradiaphragmatic respiratory muscles in conscious adult mice to examine the role of V2a neurons in patterning respiratory muscle activity. We find that silencing V2a neurons activates extradiaphragmatic respiratory muscles at rest, when they are normally inactive, with little impact on diaphragm activity. Thus, our results indicate that V2a neurons participate in a circuit that serves to constrain the activity of extradiaphragmatic respiratory muscles so that they are active only when needed.

Solving the Opioid Crisis: Respiratory Depression by Opioids as Critical End Point

Solving the Opioid Crisis: Respiratory Depression by Opioids as Critical End Point

Effect of Increased Respiratory Muscle Activation on Blood Flow to Inactive and Active Limb Muscles

It is unclear whether blood flow to inactive and active limb muscles are altered when the respiratory muscle activation is increased during submaximal exercise. PURPOSE: The purpose of this study was to clarify the effect of increasing inspiratory muscle work on blood flow to inactive and active limbs. METHODS: Healthy young men (n=7, 20±2 yrs) performed two mild bilateral dynamic knee-extension and -flexion exercises for 10 min. The trials consisted of spontaneous breathing for 5 min followed by voluntary hyperventilation either with or without inspiratory resistance for 5 min (40% of maximal inspiratory mouth pressure, inspiratory duty cycle of 50% and a breathing frequency of 40 breaths/min). Mean arterial blood pressure (MAP) was monitored using finger photoplethysmography. Blood flow to the brachial artery (inactive limb) and in femoral artery (active limb) were recorded using Doppler ultrasound. RESULTS: MAP during exercise was higher (P<0.05) with inspiratory resistance (121±6 mmHg) than without resistance (98±6 mmHg). Brachial artery blood flow increased during exercise without inspiratory resistance (127±38 ml/min) as compared with resting level, while it decreased with inspiratory resistance (69±31 ml/min). Femoral artery blood flow increased at the onset of exercise and was maintained throughout exercise without inspiratory resistance (2426±573 ml/min) and was unchanged when inspiratory resistance was added (2517±663 ml/min) (P>0.05). CONCLUSIONS: These results suggest that sympathetic control of blood redistribution to active limbs is promoted, partly, by respiratory muscle-induced metaboreflex.

The Effect of Trunk Stability Exercise on Respiratory Muscles Function in Stroke Patients

Purpose : The purpose of this study is to examine the effects of trunk stability training on improving trunk control, respiratory function, and respiratory muscle activation in stroke patients. Methods : The subjects were assigned to two groups: the intervention group (n=15) and the control group (n=15). Both groups participated in a conventional stroke rehabilitation program, but the intervention group also received trunk stability training for 30 minutes a day, 3 times a week, for 6 weeks. The main trunk stability exercise consisted of the dead bug exercise. Trunk control was assessed using a trunk impairment scale, and respiratory function (pulmonary function and respiratory muscle function) was assessed using spirometry. The data were analyzed using the Pearson correlation, independent t-test, and paired t-test. Results : Trunk control was significantly positively correlated with pulmonary function and respiratory muscle strength. Both groups showed a significant increase in trunk control and respiratory function. Conclusion : This study demonstrated that a conventional stroke rehabilitation program and trunk stability training have positive effects on respiratory function and respiratory muscle activation in stroke patients.

Severe diaphragmatic dysfunction with preserved activity of accessory respiratory muscles in a critically ill child: a case report of failure of neurally adjusted ventilatory assist (NAVA) and successful support with pressure support ventilation (PSV)

BackgroundNeurally adjusted ventilatory assist (NAVA) is an alternative to pressure support ventilation (PSV) potentially improving patient-ventilator interaction. During NAVA, diaphragmatic electrical activity (EAdi) is used to trigger the ventilator and perform a proportional respiratory assistance. We present a case in which the presence of severe bilateral diaphragmatic dysfunction led to a failure of NAVA. On the contrary, the preserved activity of the accessory inspiratory muscles allowed a successful respiratory assistance using PSV.Case presentationA 10-year-old girl developed quadriplegia after neurological surgery. Initially, no spontaneous breathing activity was present and volume controlled ventilation was necessary. Two months later spontaneous inspiratory efforts were observed and a maximal negative inspiratory force of − 20 cmH2O was recorded. In addition, a NAVA nasogastric tube was placed. The recorded EAdi signal, despite showing a phasic activity, had a very low amplitude (1–2 μV). Two brief (15 min) breathing trials to compare PSV (pressure support = 8 cmH2O) with NAVA (Gain = 5 cmH2O/μV, inspiratory trigger = 0.3 μV) were performed. On PSV, the patient was well adapted with stable tidal volumes, respiratory rates, minute ventilation, end-tidal and venous carbon dioxide levels. When switched to NAVA, her breathing pattern became irregular and she showed clear sign of increased work of breathing and distress: tidal volume dropped and respiratory rate rose, leading to an increase in total minute ventilation. Nevertheless, end-tidal and venous carbon dioxide rapidly increased (from 49 to 55 mmHg and from 52 to 57 mmHg, respectively). An electromyographic study documented an impairment of the diaphragm with preserved activity of the accessory inspiratory muscles.ConclusionsWe document the failure of mechanical assistance performed with NAVA due to bilateral diaphragmatic dysfunction in a critically ill child. The preserved activity of some accessory respiratory muscles allowed to support the patient effectively with pressure support ventilation, i.e. by applying a pneumatic trigger. The present case underlines (i) the importance of the integrity of the respiratory centers, phrenic nerves and diaphragm in order to perform NAVA and (ii) the possible diagnostic role of EAdi monitoring in complex cases of weaning failure.

Estimation of Work of Breathing from Respiratory Muscle Activity In Spontaneous Ventilation: A Pilot Study

Work of breathing (WOB) offers information that may be relevant to determine the patient’s status under spontaneous mechanical ventilation in Intensive Care Unit (ICU). Nowadays, the most reliable technique to measure WOB is based on the use of invasive catheters, but the use of qualitative observations such as the level of dyspnea is preferred as a possible indicator of WOB level. In this pilot study, the activity of three respiratory muscles were recorded on healthy subjects through surface electromyography while they were under non-invasive mechanical ventilation, using restrictive and obstructive maneuvers to obtain different WOB levels. The respiratory pattern between restrictive and obstructive maneuvers was classified with the Nearest Neighbor Algorithm with a 91% accuracy and a neural network model helped classify the samples into three WOB levels with a 89% accuracy, Low: [0.3–0.8) J/L, Medium: [0.8–1.3] J/L and Elevated: (1.3–1.8] J/L, demonstrating the relationship between the respiratory muscle activity and WOB. This technique is a promising tool for the healthcare staff in the decision-making process when selecting the best ventilation settings to maintain a low WOB. This study identified a model to estimate the WOB in different ventilatory patterns, being an alternative to invasive conventional techniques.

Stymulacja nerwu przeponowego w leczeniu centralnego bezdechu sennego u chorych z niewydolnością serca

Central sleep apnea (CSA) is characterised by a cessation of airflow in the respiratory airways during sleep due to fluctuations in respiratory drive accompanied by a cessation of respiratory muscle activity. Patients with CSA often have a Cheyne-Stokes respiration. CSA occurs in patients with various diseases including patients with heart failure (HF). It can lead to many unfavourable phenomena associated with sympathetic nervous system activation and increased mortality. Continuous positive airway pressure and other methods are used in the treatment of CSA. Recently, a new method has been developed that features stimulation of the phrenic nerve. This leads to contractions of the diaphragm and to regulation of the breathing pattern. The following paper presents the current state of knowledge on stimulation of the phrenic nerve, and its impact on respiratory parameters, physical performance and quality of life in patients with HF.

Modeling of Heart Rate Variability and Respiratory Muscle Activity in Organophosphate Poisoned Patients.

We propose an extended model of cardiovascular regulation to assess heart rate variability in patients poisoned with organophosphate during their treatment with mechanical ventilation. The model was modified to fit a population of 21 patients poisoned with organophosphorus compounds and undergoing mechanical ventilation. The extended model incorporated the respiratory muscle activity measured by surface electromyography for quantifying the vagal-sympathetic engagement during spontaneous breathing test. The order and structure of the parasympathetic and the sympathetic transfer function with respect to the original model were modified to a second-order system. In this extended model, the parameters related to the vagal-sympathetic response (corner frequency and constant gain) were correlated with respiratory muscle activity. When the diaphragm's contractions were stronger, the sympathetic corner frequency increased while the parasympathetic corner frequency and gain decreased. Thus, the proposed model could be useful to improve the ventilatory support and pharmacological treatment for patients poisoned with organophosphorus compounds considering the vagal-sympathetic response inferred from the respiratory muscle activity.

A Study on the Diaphragm and Respiratory Muscle Activity of Chronic Stroke Patients

A Study on the Diaphragm and Respiratory Muscle Activity of Chronic Stroke Patients

Measurement of intercostal muscle thickness with ultrasound imaging during maximal breathing.

[Purpose] Determining the thickness of the intercostal muscle with ultrasound imaging would be a useful parameter in evaluating respiratory muscle activity in patients with tetraplegia and neuromuscular weakness. However, it has not been clarified whether ultrasound imaging can measure changes in intercostal muscle thickness during breathing. This study aimed to measure contractions of the human intercostal muscle in the anterior, lateral, and posterior parts with ultrasound imaging during maximal breathing. [Participants and Methods] The participants were 12 healthy males. Intercostal muscle thickness was measured using ultrasound at rest and at maximal breathing. The measurement sites were the anterior, lateral, and posterior portions of the right intercostal spaces. Statistical analysis was performed using a paired t-test comparing intercostal muscle thickness at rest and maximal breathing. [Results] The thickness of the intercostal muscle showed significant increases in the first, second, third, fourth, and sixth intercostal spaces of the anterior portions. There were no significant differences in the lateral or posterior portions between rest and maximal breathing. [Conclusion] Human intercostal muscle thickness can be measured with ultrasound and increases only in the anterior portions during maximal breathing.

Effect of increased inspiratory muscle work on blood flow to inactive and active limbs during submaximal dynamic exercise.

What is the central question of this study? Increased respiratory muscle activation is associated with neural and cardiovascular consequences via the respiratory muscle metaboreflex. Does increased sympathetic vasoconstriction originating from the respiratory musculature elicit a reduction in blood flow to an inactive limb in order to maintain blood flow to an active limb? What is the main finding and its importance? Arm blood flow was reduced whereas leg blood flow was preserved during mild leg exercise with inspiratory resistance. Blood flow to the active limb is maintained via sympathetic control of blood flow redistribution when the respiratory muscle-induced metaboreflex is activated. The purpose of this study was to elucidate the effect of increasing inspiratory muscle work on blood flow to inactive and active limbs. Healthy young men (n=10, 20±2years of age) performed two bilateral dynamic knee-extension and knee-flexion exercise tests at 40% peak oxygen uptake for 10min. The trials consisted of spontaneous breathing for 5min followed by voluntary hyperventilation either with or without inspiratory resistance for 5min (40% of maximal inspiratory mouth pressure, inspiratory duty cycle of 50% and a breathing frequency of 40 breathsmin-1 ). Mean arterial blood pressure was acquired using finger photoplethysmography. Blood flow in the brachial artery (inactive limb) and in the femoral artery (active limb) were monitored using Doppler ultrasound. Mean arterial blood pressure during exercise was higher (P<0.05) with inspiratory resistance (121±7mmHg) than without resistance (99±5mmHg). Brachial artery blood flow increased during exercise without inspiratory resistance (120±31mlmin-1 ) compared with the resting level, whereas it was attenuated with inspiratory resistance (65±43mlmin-1 ). Femoral artery blood flow increased at the onset of exercise and was maintained throughout exercise without inspiratory resistance (2576±640mlmin-1 ) and was unchanged when inspiratory resistance was added (2634±659mlmin-1 ; P>0.05). These results suggest that sympathetic control of blood redistribution to active limbs is facilitated, in part, by the respiratory muscle-induced metaboreflex.

Evaluation of a Wearable Device to Determine Cardiorespiratory Parameters From Surface Diaphragm Electromyography.

The use of wearable devices in clinical routines could reduce healthcare costs and improve the quality of assessment in patients with chronic respiratory diseases. The purpose of this study is to evaluate the capacity of a Shimmer3 wearable device to extract reliable cardiorespiratory parameters from surface diaphragm electromyography (EMGdi). Twenty healthy volunteers underwent an incremental load respiratory test whilst EMGdi was recorded with a Shimmer3 wearable device (EMGdiW). Simultaneously, a second EMGdi (EMGdiL), inspiratory mouth pressure (Pmouth) and lead-I electrocardiogram (ECG) were recorded via a standard wired laboratory acquisition system. Different cardiorespiratory parameters were extracted from both EMGdiW and EMGdiL signals: heart rate, respiratory rate, respiratory muscle activity, and mean frequency of EMGdi signals. Alongside these, similar parameters were also extracted from reference signals (Pmouth and ECG). High correlations were found between the data extracted from the EMGdiW and the reference signal data: heart rate (R = 0.947), respiratory rate (R = 0.940), respiratory muscle activity (R = 0.877), and mean frequency (R = 0.895). Moreover, similar increments in EMGdiW and EMGdiL activity were observed when Pmouth was raised, enabling the study of respiratory muscle activation. In summary, the Shimmer3 device is a promising and cost-effective solution for the ambulatory monitoring of respiratory muscle function in chronic respiratory diseases.

The Effects of Trunk Control on Respiratory Muscle Strength and Activities of Daily Living in Children with Cerebral Palsy

: There is not enough evidence regarding the effects of trunk control on respiratory muscle strength and activities of daily living (ADL) in children with cerebral palsy (CP). This study was planned to investigate the effects of trunk control on respiratory muscle strength and ADL in children with spastic CP. A total of 34 children with spastic CP (M ± SD age, 9.3 ± 2.4 years) and 30 typical peers (M ± SD age, 9.7 ± 2.1 years) were included in the study. Trunk control was evaluated by the Trunk Control Measurement Scale (TCMS), ADL was evaluated by Pediatric Evaluation of Disability Inventory (PEDI), and respiratory muscle strength was evaluated by mouth pressure meter. The trunk control, respiratory muscle strength, and ADL of the children with spastic CP were significantly lower than their typically peers (P < 0.001, respectively). There were statistically significant correlations between the trunk control and maximum inspiratory pressure (MIP) (r = 0.503, P < 0.05), maximum expiratory pressure (MEP) (r = 0.465, P < 0.05), mobility subscale of Functional Skills Scale of PEDI (FSS-MS) (r = 0.570, P < 0.001), self-care subscale of Caregiver Assistance Scale of PEDI (CAS-SS) (r = 0.431, P < 0.05), mobility subscale of Caregiver Assistance Scale of PEDI (CAS-MS) (r = .607, P < 0.001), and Gross Motor Functional Classification System (GMFCS) (r = -0.522, P < 0.05) in children with spastic CP. In addition, MIP, MEP, PEDI FSS-MS, CAS-SS, and CAS-MS were independently predictors of trunk control in children with spastic CP. The results of this study demonstrate that trunk control in children with spastic CP is correlated positively to MIP, MEP values and their daily living activities and we suggest this should be taken into account when planning an intervention to improve the ability of daily living function for children with spastic CP.