Deep Diaphragmatic Breathing-Anatomical and Biomechanical Consideration.

Background: Deep diaphragmatic breathing (DDB) involves slow and fully contraction of the diaphragm with expansion of the belly during inhalation, and slow and fully contraction of the abdominal muscles with reduction of the belly during exhalation. It is the key component of the holistic mind-body exercises commonly used for patients with multimorbidity. Purpose: The purpose of this study was to re-visit and address the fundamental anatomical and biomechanical consideration of the DDB with the relevant literature. Method: Peer-reviewed publications from last the 15 years were retrieved, reviewed, and analyzed. Findings: In this article, we described the updated morphological and anatomical characteristics of the diaphragm. Then, we elucidated in a biomechanical approach how and why the DDB can work on the gastrointestinal, cardiopulmonary, and nervous systems as well as on regulating the intra-abdominopelvic pressure and mind-body interaction to coordinate the diaphragm-pelvic floor-abdominal complex for a variety of physical and physiological activities. Conclusion: Understanding of this updated DDB knowledge may help holistic healthcare professionals including holistic nurses provide better patient education and care management during the DDB or DDB-based mind-body intervention time.

Diaphragm and core stabilization exercises in low back pain: A narrative review.

INTRODUCTION: Core stabilization is a vital concept in clinical rehabilitation (including low back pain rehabilitation) and competitive athletic training. The core comprises of a complex network of hip, trunk and neck muscles including the diaphragm. AIMS: The paper aims to discuss the role of the diaphragm in core stability, summarize current evidence and put forth ideal core training strategies involving the diaphragm. METHOD: Narrative review RESULTS: The diaphragm has a dual role of respiration and postural control. Evidence suggests that current core stability exercises for low back pain are superior than minimal or no treatment, however, no more beneficial than general exercises and/or manual therapy. There appears to be a higher focus on the transversus abdominis and multifidi muscles and minimal attention to the diaphragm. We propose that any form of core stabilization exercises for low back pain rehabilitation should consider the diaphragm. Core stabilization program could commence with facilitation of normal breathing patterns and progressive systematic restoration of the postural control role of the diaphragm muscle. CONCLUSION: The role of the diaphragm is often overlooked in both research and practice. Attention to the diaphragm may improve the effectiveness of core stability exercise in low back pain rehabilitation.

Effects of intradialytic inspiratory muscle training at different intensities on diaphragm thickness and functional capacity: clinical trial protocol in patients undergoing haemodialysis.

INTRODUCTION: Patients with end-stage renal disease (ESRD) undergoing haemodialysis (HD) commonly present with a sedentary behaviour and reduced functional capacity, factors that can compromise their prognosis. Intradialytic inspiratory muscle training (IMT) can increase respiratory muscle strength and, consequently, improve functional capacity, besides being easy to apply, cheap and performed in a supervised setting. However, few studies show the effects of this type of training applied at different intensities in this population. This study aims to compare the effects of IMT at different intensities in adults with ESRD undergoing HD. METHODS AND ANALYSIS: A randomised, double-blind, sham-controlled trial will be conducted on 36 subjects randomly allocated into three groups: IMT at intensities of 30% or 50% of maximal inspiratory pressure (intervention groups), or 10% of maximal inspiratory pressure (sham-IMT). All the interventions will be supervised and performed three times per week, for 12 weeks, totalling 36 sessions. The primary outcomes are the 6-minute walk test, diaphragm thickness and the response of VO2peak post-intervention. Respiratory muscle strength, 24-hour ambulatory blood pressure measurement and the Kidney Disease Quality of Life 36-item short form survey will be evaluated as secondary outcomes. ETHICS AND DISSEMINATION: This study has been approved by the Research Ethics Committee of the Hospital de Clínicas de Porto Alegre (ID: 2020-0458). The results of this study will be disseminated by conference presentations and peer-reviewed journal. TRIAL REGISTRATION NUMBER: NCT04660383.

Training the equine respiratory muscles: Ultrasonographic measurement of muscle size.

BACKGROUND: Limited information exists regarding changes in the size of respiratory and locomotor muscles in response to exercise training in the Thoroughbred racehorse. OBJECTIVES: To describe and compare the responses of the respiratory and locomotor muscles to conventional exercise training and inspiratory muscle training (IMT). STUDY DESIGN: Prospective randomised controlled trial. METHODS: Thoroughbred racehorses, in training for competition in National Hunt races, were recruited from two training establishments. Ultrasonographic images were obtained for selected muscles of the upper airway, diaphragm, accessory respiratory, and locomotor systems and their sizes measured. Examinations were performed at three timepoints: (A) when unfit, (B) following 12 weeks of conventional exercise training and (C) following 10-12 weeks continued training at race fitness. In addition, horses at yard 1 performed IMT, between timepoint B and C, and were randomly assigned into high-load (treatment) or low-load (control) group. Repeated measures models were constructed to compare the change in muscle measurements over time, and to investigate the effects of yard, previous airway surgery and IMT on the change in ultrasonographic size measurements obtained. RESULTS: Upper airway muscle size increased in response to conventional race training between timepoints A-C, and B-C. Diaphragm size increased in response to conventional exercise training between timepoints A and B. The diaphragm size of horses that undertook high-load IMT was either maintained or increased, whereas diaphragm size decreased in horses that undertook low-load IMT or no IMT between timepoints B and C. A significant interaction between gluteal muscle size and airway surgery status was observed, with greater gluteal muscle thicknesses measured in horses that had not previously undergone airway surgery (left gluteal 3.9%, p < 0.001; right 4.5%, p = 0.04). MAIN LIMITATIONS: Low number of horses underwent IMT. CONCLUSIONS: Respiratory and locomotor muscles increase in size in response to conventional exercise training, with a further change in diaphragm size in response to inspiratory muscle training.

Effects of Manual Therapy on the Diaphragm in the Musculoskeletal System: A Systematic Review.

OBJECTIVES: To analyze the effects at the musculoskeletal level of manual treatment of the diaphragm muscle in adults. DATA SOURCES: Systematic review using 4 databases: PubMed, Science Direct, Web of Science, and Scopus. STUDY SELECTION AND DATA EXTRACTION: Two independent reviewers applied the selection criteria and assessed the quality of the studies using the Physiotherapy Evidence Database scale for experimental studies. A third reviewer intervened in cases where a consensus had not been reached. A total of 9 studies were included in the review. DATA SYNTHESIS: Manual therapy directed to the diaphragm has been shown to be effective in terms of the immediate increase in diaphragmatic mobility and thoracoabdominal expansion. The immediate improvement in the posterior muscle chain flexibility test is another of the most frequently found findings in the evaluated studies. Limited studies show improvements at the lumbar and cervical level in the range of motion and in pain. CONCLUSION: Manual diaphragm therapy has shown an immediate significant effect on parameters related to costal, spinal, and posterior muscle chain mobility. Further studies are needed, not only to demonstrate the effectiveness of manual diaphragm therapy in the long-term and in symptomatic populations, but also to investigate the specific neurophysiological mechanisms involved in this type of therapy.

Influence of Chest and Diaphragm Manual Therapy on the Spirometry Parameters in Patients with Cerebral Palsy: A Pilot Study.

OBJECTIVE: To evaluate the influence of manual therapy of the chest and diaphragm on the spirometry parameters in patients with cerebral palsy (CP). METHOD: The study was carried out on 20 youths with CP. All participated in 6 sessions (3 sham and 3 actual), with measurements of spirometry at baseline, postsham therapies 1 and 3, before actual therapy, and postactual therapy sessions 1 and 3. Two manual techniques were included: soft tissue mobilization of the chest and the diaphragm. RESULTS: After the first actual therapy, there was a significant (p < 0.01) improvement in forced vital capacity (FVC) by 0.23 L (8% of the average predicted value) and forced expiratory volume in one second (FEV1) by 0.18 L (7% of the average predicted value) as compared to results before the therapy. Change in FVC parameter was clinically significant, whereas change in FEV1 was not clinically significant. After sham therapy, there was no improvement in spirometry parameters as compared to baseline results. CONCLUSION: Single-time manual therapy of the chest and diaphragm has a positive effect on FVC and FEV1.

Restoration of breathing after opioid overdose and spinal cord injury using temporal interference stimulation.

Respiratory insufficiency is a leading cause of death due to drug overdose or neuromuscular disease. We hypothesized that a stimulation paradigm using temporal interference (TI) could restore breathing in such conditions. Following opioid overdose in rats, two high frequency (5000 Hz and 5001 Hz), low amplitude waveforms delivered via intramuscular wires in the neck immediately activated the diaphragm and restored ventilation in phase with waveform offset (1 Hz or 60 breaths/min). Following cervical spinal cord injury (SCI), TI stimulation via dorsally placed epidural electrodes uni- or bilaterally activated the diaphragm depending on current and electrode position. In silico modeling indicated that an interferential signal in the ventral spinal cord predicted the evoked response (left versus right diaphragm) and current-ratio-based steering. We conclude that TI stimulation can activate spinal motor neurons after SCI and prevent fatal apnea during drug overdose by restoring ventilation with minimally invasive electrodes.

Dynamics of ventilation parameters at different load intensities and the options to influence it by a breathing exercise.

BACKGROUND: Minimizing the energy required for breathing muscles is based on the adaptation of the respiratory muscles which is reflected in the reduction of breathing frequency (BF) and tidal volume (VT) increase. This may be influenced through a targeted BE and the quality of breathing may be linked to endurance performance. Aim of this study was assess dynamic ventilation parameters at different load intensities and their changes due to the systematic breathing exercise (BE). METHODS: Study recruit 36 runners of both sexes with a mean age 16.8±1.6 years. A random distribution was performed. The intervention program consisted of a set of BE aimed at the activation of the diaphragm. We monitored the dynamics of ventilation parameters at intensities 2, 3, 4 W/kg during a stepped test on a bicycle ergometer. RESULTS: The BE was focused on the activation of the diaphragm for a 12.2±3.6 minutes per day, sixteen weeks. After eight weeks, there were significant changes in VT and BF (P<0.05). After sixteen weeks there was a significant increase in VT of 5.7-18.3% (P<0.01), depending on the load level, BF values decreased significantly by 5.4-14.4% (P<0.01). VE and VO2 values were without changes. There were no significant changes in the control group. CONCLUSIONS: It was confirmed that the two-month BE intervention focused on the activation of the diaphragm is sufficient and resulted in a significant change in the values of dynamic ventilation parameters. After four months of intervention, the changes are significantly greater compared with values found after a two-month intervention period.

Chronic vomiting in children: A prospective study reveals rumination syndrome is an important etiology that is underdiagnosed and untreated.

BACKGROUND: The diagnosis of rumination syndrome is frequently overlooked, and under-recognized; children are subjected to unnecessary testing and inappropriate treatment for a condition which can be diagnosed clinically and managed easily. In the first ever systematic exploration of this condition from India, we present a prospective study on children with chronic vomiting in which rumination emerged as the predominant cause. METHODS: This was a prospective study in which all consecutive children (5-18 years) presenting with chronic or recurrent vomiting of at least 2-month duration were enrolled. Clinical history was assessed by a physician-administered questionnaire. All subjects underwent standard testing followed by additional investigations as required. The ROME III criteria were used. RESULTS: Fifty children (28 boys, age 12.2 + 3 years) were enrolled. Diagnosis was rumination syndrome 30, cyclical vomiting 8, functional vomiting 6, intestinal tuberculosis 4, intestinal malrotation 1, and superior mesenteric artery syndrome 1. Children with rumination syndrome had a relapsing and remitting (12, 40%) or a chronically symptomatic course (18, 60%). These children received incorrect diagnoses (26, 87%) or no diagnosis (3, 10%) and extensive investigation before referral. Before referral, children with rumination syndrome were treated with a median of four drugs (range 1 to 9); two underwent surgery (appendectomy) for their symptoms while one child was subjected to electroconvulsive therapy. Overall, resolution after treatment was seen in 26 (87%) with a relapse in 8 (27%) children. CONCLUSION: The diagnosis of rumination syndrome is delayed and these children are often inappropriately treated. Therapy in the form of diaphragmatic breathing has a good success rate.

Effect of inspiratory resistive training on diaphragm shear modulus and accessory inspiratory muscle activation.

This study aimed to elucidate changes in diaphragm and accessory inspiratory muscle (sternocleidomastoid (SCM) muscle and intercostal muscle (IC)) function after a 6-week training program. Nineteen male elite collegiate swimmers were assigned to either a control group (n = 9) or training group (n = 10). The subjects in the training group performed 30 maximum inspirations at a load resistance of 50% of maximum inspiratory mouth pressure (PImax) using an inspiratory muscle training device. These were conducted twice per day and 6 days per week. At baseline and after 6 weeks, PImax, shear modulus of the diaphragm, and electromyograms (EMG) of the SCM and IC during a maximal inspiratory maneuver were evaluated. Relative change in PImax was greater in the training group than in controls. The shear modulus during a PImax maneuver had increased significantly in both groups after 6 weeks. EMG amplitudes of the SCM increased in the training group after 6 weeks, but not in the control group. EMG amplitudes of the IC did not change after 6 weeks in either group. These results suggest that 6-week inspiratory resistive training significantly improves the activation of the SCM, which could be one of the major mechanisms behind increases in inspiratory muscle strength after resistive training. Novelty Six-week inspiratory resistive training increased diaphragm stiffness during maximal inspiration maneuver. Six-week inspiratory resistive training increased electromyogram amplitudes of the sternocleidomastoid during maximal inspiration maneuver.

Differences in Respiratory Muscle Responses to Hyperpnea or Loaded Breathing in COPD.

INTRODUCTION: We aimed to compare acute mechanical and metabolic responses of the diaphragm and rib cage inspiratory muscles during two different types of respiratory loading in patients with chronic obstructive pulmonary disease. METHODS: In 16 patients (age, 65 ± 13 yr; 56% male; forced expiratory volume in the first second, 60 ± 6%pred; maximum inspiratory pressure, 82 ± 5%pred), assessments of respiratory muscle EMG, esophageal pressure (Pes) and gastric pressures, breathing pattern, and noninvasive assessments of systemic (V˙O2, cardiac output, oxygen delivery and extraction) and respiratory muscle hemodynamic and oxygenation responses (blood flow index, oxygen delivery index, deoxyhemoglobin concentration, and tissues oxygen saturation [StiO2]), were performed during hyperpnea and loaded breathing. RESULTS: During hyperpnea, breathing frequency, minute ventilation, esophageal and diaphragm pressure-time product per minute, cardiac output, and V˙O2 were higher than during loaded breathing (P < 0.05). Average inspiratory Pes and transdiaphragmatic pressure per breath, scalene (SCA), sternocleidomastoid, and intercostal muscle activation were higher during loading breathing compared with hyperpnea (P < 0.05). Higher transdiaphragmatic pressure during loaded breathing compared with hyperpnea was mostly due to higher inspiratory Pes (P < 0.05). Diaphragm activation, inspiratory and expiratory gastric pressures, and rectus abdominis muscle activation did not differ between the two conditions (P > 0.05). SCA-blood flow index and oxygen delivery index were lower, and SCA-deoxyhemoglobin concentration was higher during loaded breathing compared with hyperpnea. Furthermore, SCA and intercostal muscle StiO2 were lower during loaded breathing compared with hyperpnea (P < 0.05). CONCLUSION: Greater inspiratory muscle effort during loaded breathing evoked larger rib cage and neck muscle activation compared with hyperpnea. In addition, lower SCA and intercostal muscle StiO2 during loaded breathing compared with hyperpnea indicates a mismatch between inspiratory muscle oxygen delivery and utilization induced by the former condition.

Investigation into Deep Breathing through Measurement of Ventilatory Parameters and Observation of Breathing Patterns.

In this protocol, two deep breathing patterns were shown to 15 participants to determine an easy yet effective method of breathing exercise for future application in a clinical setting. The women in their twenties were seated comfortably in a chair with back support. They were fitted with an airtight mask connected to a gas analyzer. Three electrodes were placed on the chest connected to a wireless transmitter for relaying to the electrocardiograph. They executed a 5 min rest phase, followed by 5 min of deep breathing with a natural breathing pattern, terminating with a 5 min rest phase. This was followed by a 10 min intermission before commencing the second instruction phase of substituting the natural breathing pattern with the diaphragmatic breathing pattern. Simultaneously, the following took place: a) continuous collection, measurement and analysis of the expired gas to assess the ventilatory parameters on a breath-by-breath basis; b) measurement of the heart rate by an electrocardiograph; and c) videotaping of the participant's thoracoabdominal movement from a lateral aspect. From the video capture, the investigators carried out visual observation of the fast-forward motion-images followed by classification of the breathing patterns, confirming that the participants had carried out the method of deep breathing as instructed. The amount of oxygen uptake revealed that, during deep breathing, the work of breathing decreased. The results from the expired minute ventilation, respiration rate and tidal volume confirmed increased ventilatory efficiency for deep breathing with the natural breathing pattern compared to that with the diaphragmatic breathing pattern. This protocol suggests a suitable method of instruction for assessing deep breathing exercises on the basis of oxygen consumption, ventilatory parameters, and chest wall excursion.

Ultrasound Evaluation of Diaphragmatic Mobility and Contractility After Osteopathic Manipulative Techniques in Healthy Volunteers: A Prospective, Randomized, Double-Blinded Clinical Trial.

OBJECTIVE: The purpose of this study was to investigate the effect of a session of osteopathic manipulative techniques on diaphragmatic motion and thickness in healthy participants. METHODS: This was a prospective, randomized, double-blinded, case vs sham vs control clinical trial performed in an outpatient osteopathic clinic in Rome, Italy. Sixty-seven healthy participants, mean age 40.4 ± 14.5 years, received an ultrasound evaluation of diaphragmatic motion and thickness, followed by a systematic osteopathic evaluation. After randomization, the experimental group (n = 22) received osteopathic manipulation, whereas the sham (n = 22) and the control (n = 22) groups had a light touch approach and simple observation, respectively. After a 1-session intervention, new osteopathic and ultrasound assessments were repeated in all participants. RESULTS: A statistically significant increase in diaphragmatic mobility was observed in the experimental group after the osteopathic manipulation (Δ = 14.5 mm, P < .001; analysis of variance P < .001 vs both sham: Δ = -0.22 mm, and control: Δ = -2.09 mm groups). A strong linear relationship was observed between the diaphragmatic motion gradient, measured with ultrasonography, and the score assigned by the operator evaluating the change of diaphragm mobility after intervention. CONCLUSION: Osteopathic techniques used in this study improved the diaphragmatic motion (but not the muscle thickness) in healthy participants. Further studies are needed to confirm our findings and eventually identify the clinical conditions that may benefit from osteopathic manipulative treatment of the diaphragm.

Immediate effects of diaphragmatic myofascial release on the physical and functional outcomes in sedentary women: A randomized placebo-controlled trial.

BACKGROUND: Although diaphragmatic myofascial release techniques are widely used in clinical practice, few studies have evaluated the simultaneous acute effects of these techniques on the respiratory and musculoskeletal systems. OBJECTIVE: To evaluate the immediate effects of diaphragmatic myofascial release in sedentary women on the posterior chain muscle flexibility; lumbar spine range of motion; respiratory muscle strength; and chest wall mobility. DESIGN: A randomized placebo-controlled trial with concealed allocation, intention-to-treat analysis, and blinding of assessors and participants. PARTICIPANTS: Seventy-five sedentary women aged between 18 and 35 years. INTERVENTION: The sample was randomly allocated into one of two groups; the experimental group received two diaphragmatic myofascial release techniques in a single session, and the control group received two placebo techniques following the same regimen. OUTCOMES MEASURES: The primary outcome was chest wall mobility, which was analyzed using cirtometry. The secondary outcomes were flexibility, lumbar spine range of motion, and respiratory muscle strength. Outcomes were measured before and immediately after treatment. RESULTS: The manual diaphragm release techniques significantly improved chest wall mobility immediately after intervention, with a between-group difference of 0.61 cm (95% CI, 0.12-1.1) for the axillary region, 0.49 cm (95% CI, 0.03-0.94) for the xiphoid region, and 1.44 (95% CI, 0.88-2.00) for the basal region. The techniques also significantly improved the posterior chain muscle flexibility, with a between-group difference of 5.80 cm (95% CI, 1.69-9.90). All movements except flexion of the lumbar spine significantly increased. The effects on respiratory muscle strength were non-significant. CONCLUSION: The diaphragmatic myofascial release techniques improve chest wall mobility, posterior chain muscle flexibility, and some movements of the lumbar spine in sedentary women. These techniques could be considered in the management of people with reduced chest wall and lumbar mobility. TRIAL REGISTRATION: NCT03065283.

Effect of respiratory guidance on internal/external respiratory motion correlation for synchrotron-based pulsed heavy-ion radiotherapy.

Having implemented an audio-visual biofeedback (BFB) method for respiratory-gated radiotherapy of synchrotron-based pulsed heavy-ion beam delivery with tracking of external abdominal wall motion, this study evaluated the feasibility of the respiratory guidance method on thoracic and abdominal cancer patients, and the internal/external respiratory motion consistency under respiratory guidance maneuvers due to its interactive intervention in free breathing (FB). A total of 42 breathing traces from seven lung and breast cancer patients and corresponding fluoroscopy movies under FB, standard breath hold (stBH) and representative breath hold (reBH) guidance maneuvers were analyzed. Diaphragm motions were measured manually on a frame-by-frame basis. Mean absolute deviation (MAD) values of the measured external motion curves were calculated for the FB and guidance maneuvers, and the internal/external motion consistencies were compared with a linear fit. Compared with FB, the MAD values were reduced significantly with respiratory guidance maneuvers. The mean internal/external correlations of the first treatment fraction were determined to be 0.96 ± 0.03, 0.97 ± 0.02, and 0.97 ± 0.03 for the FB, stBH and reBH guidance maneuvers, respectively, and were 0.95 ± 0.03, 0.97 ± 0.03, and 0.98 ± 0.02 for the second treatment fraction. No phase shift between the two breathing signals was observed, and good reproducibility of consistency of breathing guidance between the two fractions was achieved. These results demonstrated that treatment precision could be improved for cancer patients with audio-visual BFB, and a strong correlation between diaphragm motion and abdominal wall motion was obtained. The use of audio-visual BFB improved the regularity of both internal and external motions, allowing confident use of the audio-visual BFB method by tracking of the external abdominal wall motion to synchrotron-based heavy-ion radiotherapy.

Diaphragm electromyography guidance for a lung transplant recipient with difficult weaning from mechanical ventilation: A case report.

RATIONALE: Many factors contribute to a complicated postoperative course following difficult weaning off a ventilator after lung transplantation. PATIENT CONCERNS: A female patient underwent a successful surgery but received a size-mismatched lung graft. The graft had been pruned before transplantation. She experienced delayed ventilator weaning 3 days after lung transplantation. DIAGNOSES: A postoperative X-ray revealed a normal mediastinal structure and diaphragm position. Diaphragmatic function was assessed by diaphragm electromyography (EMGdi) via esophageal and surface electrodes. EMGdi showed decreased left compound motor action potentials (CMAPs), prolonged left phrenic nerve conduction time (PNCT), failure to induce right CMAPs and PNCT under bilateral magnetic stimulation, and right phrenic nerve injury. INTERVENTIONS: She was treated with neural nutritional support and prescribed rehabilitation measures such as strengthening limb activities on the bed. OUTCOMES: The patient finally achieved satisfactory outcomes after an early diagnosis and medical interventions. LESSONS: Lung size mismatch before transplantation and phrenic nerve injury during surgery should be avoided wherever possible.

Diaphragm Pacing.

Diaphragm pacing (DP) is a useful and cost-effective alternative to mechanical ventilation in patients with ventilator-dependent spinal cord injury and central hypoventilation syndrome. Patients with SCI should be carefully screened to assess the integrity of their phrenic nerves. In eligible patients, DP improves mobility, speech, olfaction, and quality of life. The stigma of being attached to a mechanical device and risk of ventilator disconnection are eliminated. There is also some evidence that DP results in a reduction in the rate of respiratory tract infections. DP is associated with infrequent side effects and complications, such as wire breakage, radiofrequency failure, and infection.

Diaphragm Dysfunction in Critical Illness.

The diaphragm is the major muscle of inspiration, and its function is critical for optimal respiration. Diaphragmatic failure has long been recognized as a major contributor to death in a variety of systemic neuromuscular disorders. More recently, it is increasingly apparent that diaphragm dysfunction is present in a high percentage of critically ill patients and is associated with increased morbidity and mortality. In these patients, diaphragm weakness is thought to develop from disuse secondary to ventilator-induced diaphragm inactivity and as a consequence of the effects of systemic inflammation, including sepsis. This form of critical illness-acquired diaphragm dysfunction impairs the ability of the respiratory pump to compensate for an increased respiratory workload due to lung injury and fluid overload, leading to sustained respiratory failure and death. This review examines the presentation, causes, consequences, diagnosis, and treatment of disorders that result in acquired diaphragm dysfunction during critical illness.