Single breath counting in the assessment of pulmonary function

Single breath count test and its applications in clinical practice: a systematic review

Background

Single breath count test (SBCT) may be a reproducible, rapid, easy to perform and easy to interpret substitute to spirometry especially in low resource settings for certain conditions. Its interest has been rekindled with the recent COVID-19 pandemic and it can be done as a part of tele-medicine as well.

Objectives

The objective of this review was to summarize the evidence of SBCT in clinical practice.

Methods

The authors searched EMBASE, PubMed and Google Scholar for all the relevant articles as per exclusion and inclusion criteria. Two authors independently screened all the studies. Newcastle Ottawa Scale was used to assess the quality of the studies. The systematic review was carried following the PRISMA guidelines.

Results

After the rigorous process of screening, a total of 13 articles qualified for the systematic review. SBCT greater than 25 had sensitivity of greater than 80% in diagnosing myasthenia gravis exacerbation and SBCT less than or equal to 5 predicted the need for mechanical ventilation in Guillain-Barre syndrome (GBS) patients with 95.2% specificity. Also, Single breath count correlated significantly with forced expiratory volume in 1 sec (FEV1) and forced vital capacity (FVC) in children with pulmonary pathology and in patients with COVID-19 it was used to rule out the need for noninvasive respiratory support.

Conclusion

SBCT will undoubtedly be an asset in low resource settings and in tele-medicine to assess the prognosis and guide management of different respiratory and neuromuscular diseases.

Single breath counting technique to assess pulmonary function: a systematic review and meta-analysis

Pulmonary function is usually assessed by measuring Vital Capacity (VC) using equipment such as a spirometer or ventilometer, but these are not always available to the population, as they are relatively expensive tests, difficult to transport and require trained professionals. However, the single breath counting technique (SBCT) appears as a possible alternative to respiratory function tests, to help in the pathophysiological understanding of lung diseases. The objective is to verify the applicability of the SBCT as a parameter for evaluating VC. This is a systematic review registered in the International Prospective Register of Systematic Reviews (CRD42023383706) and used for PubMed®, Scientific Electronic Library Online, LILACS, EMBASE, and Web of Science databases of articles published until January 2023. Methodological quality regarding the risk of bias was assessed using Quality Assessment of Diagnostic Accuracy Studies-2 and National Institutes of Health tools. Eleven of a total of 574 studies were included, of these, nine showed a correlation between VC and SBCT (weak in healthy, moderate in neuromuscular and strong in hospitalized patients). One study of hospitalized patients accurately identified a count value of 21 for a VC of 20 ml kg-1(Sensitivity = 94% and Specificity = 77%), and another estimated a count lower than 41 for a VC below 80% of predicted in patients with neuromuscular dystrophy (Sensitivity = 89% and Specificity = 62%), and another showed good intra and inter-examiner reproducibility in young, adult, and elderly populations. A meta-analysis of three studies showed a moderate correlation in subjects with neuromuscular diseases (r= 0.62, 95% CI = 0.52-0.71,p< 0.01). A high risk of bias was identified regarding the justification of the sample size and blinding of the evaluators. SBCT has been presented as an alternative to assess VC in the absence of specific equipment. There is a clear relationship between SBCT and VC, especially in neuromuscular and hospitalized individuals. New validation studies conducted with greater control of potential bias risks are necessary.

Single Breath Counting for Diagnosis and Prediction of Severity of Acute Asthma Exacerbation in Children

OBJECTIVES

To find correlation between single breath counting (SBC) and spirometry in acute exacerbation of asthma in children.

METHODS

A cross-sectional observational study including all children aged 6-12 y age, who presented in outpatient department or emergency room with acute exacerbation of asthma, not fitting in exclusion criteria were enrolled. SBC and spirometry parameters were obtained before treatment and 1 h after initiating treatment (GINA 2017 Guidelines).

RESULTS

Significant correlation was observed in SBC and FVC (r = 0.349), FEV1 (r = 0.439), FEF25-75 (r = 0.424), and PEF (r = 0.593). Cutoff value of SBC of 23 was found to be suggestive of severe/life-threatening asthma with sensitivity of 83.3% and specificity of 84.4%. No significant association was found between percent change in SBC and spirometry parameters in response to treatment.

CONCLUSIONS

SBC can be used to predict PEF, FEV1, FVC, and FEF25-75 of a patient aged between 6 and 12 y during acute asthma exacerbation. The observed cutoff value of 23 of SBC score has a good sensitivity and specificity to identify life-threatening/severe exacerbation. SBC score significantly increases in response to therapy.

Single count breath test for the evaluation of respiratory function in Myasthenia Gravis: A systematic review

BACKGROUND

Myasthenia gravis (MG) can have a variety of respiratory presentations, ranging from mild symptoms through to respiratory failure. The evaluation of respiratory function in MG can be limited by accessibility to testing facilities, availability of medical equipment, and facial weakness. The single count breath test (SCBT) may be a useful adjunct in the evaluation of respiratory function in MG.

METHOD

A systematic review of the databases PubMed, EMBASE, and the Cochrane Library was conducted from inception to October 2022 in accordance with PRISMA guidelines and was registered on PROSPERO.

RESULTS

There were 6 studies that fulfilled the inclusion criteria. The described method of evaluating SCBT involves inhaling deeply, then counting at two counts per second, in English or Spanish, sitting upright, with normal vocal register, until another breath needs to be taken. The identified studies support that the SCBT has a moderate correlation with forced vital capacity. These results also support that SCBT can assist the identification of MG exacerbation, including via assessment over the telephone. The included studies support a threshold count of ≥ 25 as consistent with normal respiratory muscle function. Although further analysis is needed, the included studies describe the SCBT as a quick bedside tool that is inexpensive and well tolerated.

CONCLUSIONS

The results of this review support the clinical utility of the SCBT in assessing respiratory function in MG and describe the most current and effective methods of administration.

Validation of the Single Breath Count Test for Assessment of Inspiratory Muscle Strength in Healthy Subjects and People with Neuromuscular Disorders

OBJECTIVE

This study aimed to validate the single breath count test (SBCT) against volitional measures of respiratory muscle function in healthy subjects and people with neuromuscular disorders (NMD; n = 100 per group).

METHODS

Testing comprised upright and supine SBCT, forced vital capacity (FVC), maximum inspiratory pressure (MIP), and sniff nasal inspiratory pressure (SNIP). Predictability of FVC by SBCT was assessed using logarithmic regression analysis. Receiver operating characteristics curves were used to identify SBCT thresholds for lung restriction (FVC < 80% predicted), inspiratory muscle weakness (MIP < 60 cmH2O), and indication for non-invasive ventilation (NIV) in NMD patients.

RESULTS

In both groups, SBCT showed moderate correlation with FVC. In patients, SBCT values were also correlated with MIP and SNIP. Strength of correlations was similar with supine and upright SBCT which accounted for 23.7% of FVC variance in healthy individuals (44.5% in patients). Predictive thresholds of upright SBCT were < 27 for MIP < 60 cmH2O (sensitivity 0.61/specificity 0.86), <39 for NIV indication (0.92/0.46), and <41 for FVC < 80% predicted (0.89/0.62).

CONCLUSION

The SBCT is positively correlated with spirometry. It predicts both lung restriction and NIV indication in NMD patients. The SBCT allows for remote monitoring and may substitute for spirometry/manometry if appropriate devices are unavailable.

Effect of smoking on vital hemodynamic parameters and lipid profile of young smokers

Background and objectives: Tobacco use is associated with cardiovascular, respiratory and peripheral vascular diseases. The short term effects of tobacco smoking on vital hemodynamic parameters and lipid profile of young smoker with increased quantity of smoking is still debatable. The objective of this study was to evaluate the effect of smoking on vital hemodynamic parameters and lipid profile of young smokers. Materials and methods: The current study was an observational cross sectional study conducted in a tertiary care hospital over a period of 18 months and included smokers and non-smokers. Data on vital hemodynamic parameters like blood pressure, heart rate, oxygen saturation (SPO2) and lipid profile were collected. Chi-square and analysis of variance (ANOVA) tests were used to analyze the data. Results: A total of 80 smokers and 80 non-smokers were enrolled in the study. Blood pressure, heart rate and mean SpO2 were significantly (p<0.001) lower in non-smokers compared to smokers. Breath holding time (BHT) and single breath count (SBC) were higher in non-smokers. Mean values of total cholesterol (T-chol), low density lipoprotein (LDL) and triglyceride (TG) were significantly (p<0.001) higher in smokers than non-smokers, while high density lipoprotein (HDL) was significantly low in smokers. SBP, T -chol and TG significantly (p<0.05) increased as the quantity of smoking increased. Conclusion: Smoking is associated with derangement of vital hemodynamic parameters and lipid profile across the age. Anti-smoking campaign should be organized to discourage both personal smoking and smoking in public places. IMC J Med Sci. 2023. 17(1): 007. DOI : https://doi.org/10.55010/imcjms.17.007 *Correspondence: Bhupendra Kumar Jain, Department of Pulmonary Medicine, School of Chhindwara Institute Of Medical Sciences, Jabalpur Medical University, Chhindwara, Madhya Pradesh, India. Email: drbhupendrakjain@gmail.com

The Effectiveness of Manual Therapy in the Cervical Spine and Diaphragm, in Combination with Breathing Reeducation Exercises, in Patients with Non-Specific Chronic Neck Pain: Protocol for Development of Outcome Measures and a Randomized Controlled Trial

Until now, non-specific chronic neck pain has mainly been considered as a musculoskeletal system dysfunction, with associated psychological involvement due to its prolonged or recurrent nature. However, patients with non-specific chronic neck pain frequently additionally exhibit respiratory dysfunction. Emerging evidence suggests that addressing the respiratory dysfunction in these patients will provide additional therapeutic benefits in musculoskeletal and respiratory-related outcomes for several reasons (biomechanical, biochemical, and psychological). Motor control dysfunction of the muscles surrounding the spine (diaphragm included) negatively affects the mechanics and biochemistry of breathing (pH-homeostasis). An impaired and ineffective breathing pattern has been recognized as the primary source of many unexplained symptoms (anxiety, depression, confusion, chest pain, hypocapnia, and breathlessness) in patients with non-specific chronic neck pain. The proposed protocol’s purpose is dual: to assess the relative effectiveness of manual therapy in the cervical spine and the diaphragm, in combination with breathing reeducation exercises, along with cervical spine manual therapy or usual physical therapy care on the underlying dysfunctions in patients with non-specific chronic neck pain via a randomized controlled clinical trial, and to validate part of the outcome measures. Several musculoskeletal and respiratory dysfunction outcomes will be employed to delimit the initial extent and level of dysfunction and its resolution with the treatments under study.

Peak expiratory flow and the single-breath count test as markers of respiratory function in patients with myasthenia gravis

INTRODUCTION

Myasthenia gravis (MG) is an antibody-mediated autoimmune disease characterised by fluctuating, fatigable muscle weakness, frequently involving bulbar and respiratory muscles. Considering the severity of respiratory involvement in MG, routine evaluation of respiratory function is essential. The aim of this study was to identify a useful clinical marker of respiratory involvement in patients with MG.

METHODS

We performed an observational study of patients with MG. All cases were evaluated with the single-breath count test, peak expiratory flow (PEF), a modified Medical Research Council dyspnoea scale (mMRC), and a neck strength assessment. The results of these parameters were correlated with forced vital capacity (FVC), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP).

RESULTS

The study included 45 patients with MG: 2 patients classified as grade I on the Myasthenia Gravis Foundation of America classification at the time of evaluation, 35 classified as grade II, 7 classified as grade III, and one classified as grade IV. Positive correlations were found between single-breath count test scores and FVC values (r = 0.57, P = .000), and between PEF and FVC values (r = 0.76, P = .000). Severity of dyspnoea according to the mMRC scale showed a negative correlation with FVC values (r = -0.31, P = .03). PEF also showed a significant correlation with MEP (r = 0.51, P = .002).

CONCLUSIONS

PEF, the single-breath count test, and the mMRC scale are useful measures for evaluating respiratory function in patients with MG.

An unusual occurrence of opsoclonus and liver enzymes elevation in a patient with acute motor and sensory axonal neuropathy subtype of Guillain-Barré syndrome

Background

Acute motor and sensory axonal neuropathy (AMSAN) is a subtype of Guillain-Barré syndrome (GBS) differentiated by nerve conduction studies (NCS) and characterized by symmetric ascending paralysis often involving respiratory muscles. While opsoclonus, which is involuntary chaotic rapid eye movements, is not a common manifestation of GBS. Moreover, little published data are available on the relation between liver enzymes elevation and GBS.

Case presentation

A 42-year-old man presented to Al Mouwassat University Hospital with weakness in all limbs and dyspnea. Examination showed an elevated respiratory rate, hyporeflexia, and decreased strength of upper and lower limbs. Analysis of cerebrospinal fluid revealed an albuminocyto-dissociation suggesting the diagnosis of GBS and subsequent plasmapheresis. NCS confirmed a diagnosis of AMSAN. Elevation in liver enzymes was noticed prompting further exploration with no positive findings. Despite treatment efforts, the patient developed severe dyspnea, deterioration in cognitive abilities, and opsoclonus with a normal brain MRI. Unfortunately, he developed respiratory failure which lead to his death.

Conclusion

In this case, we highlight the occurrence of opsoclonus which is a rarely-encountered manifestation of GBS, in addition to an unexplained elevated liver enzyme, the thing that could contribute to larger research to further comprehend the pathophysiology of GBS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-022-02599-0.

Motor neuron, peripheral nerve, and neuromuscular junction disorders

In amyotrophic lateral sclerosis (ALS), Guillain-Barré syndrome (GBS), and neuromuscular junction disorders, three mechanisms may lead, singly or together, to respiratory emergencies and increase the disease burden and mortality: (i) reduced strength of diaphragm and accessory muscles; (ii) oropharyngeal dysfunction with possible aspiration of saliva/bronchial secretions/drink/food; and (iii) inefficient cough due to weakness of abdominal muscles. Breathing deficits may occur at onset or more often along the chronic course of the disease. Symptoms and signs are dyspnea on minor exertion, orthopnea, nocturnal awakenings, excessive daytime sleepiness, fatigue, morning headache, poor concentration, and difficulty in clearing bronchial secretions. The "20/30/40 rule" has been proposed to early identify GBS patients at risk for respiratory failure. The mechanical in-exsufflator is a device that assists ALS patients in clearing bronchial secretions. Noninvasive ventilation is a safe and helpful support, especially in ALS, but has some contraindications. Myasthenic crisis is a clinical challenge and is associated with substantial morbidity including prolonged mechanical ventilation and 5%-12% mortality. Emergency room physicians and consultant pulmonologists and neurologists must know such respiratory risks, be able to recognize early signs, and treat properly.

Single-Breath Counting Test Predicts Non-Invasive Respiratory Support Requirements in Patients with COVID-19 Pneumonia

The use of non-invasive respiratory strategies (NIRS) is crucial to improve oxygenation in COVID-19 patients with hypoxemia refractory to conventional oxygen therapy. However, the absence of respiratory symptoms may delay the start of NIRS. The aim of this study was to determine whether a simple bedside test such as single-breath counting test (SBCT) can predict the need for NIRS in the 24 h following the access to Emergency Department (ED). We performed a prospective observational study on 120 patients with COVID-19 pneumonia. ROC curves were used to analyze factors which might predict NIRS requirement. We found that 36% of patients had normal respiratory rate and did not experience dyspnea at rest. 65% of study population required NIRS in the 24 h following the access to ED. NIRS-requiring group presented lower PaO₂/FiO₂ (235.09 vs. 299.02), SpO₂/FiO₂ ratio (357.83 vs. 431.07), PaCO₂ (35.12 vs. 40.08), and SBCT (24.46 vs. 30.36) and showed higher incidence of dyspnea at rest (57.7% vs. 28.6%). Furthermore, SBCT predicted NIRS requirement even in the subgroup of patients without respiratory symptoms (AUC = 0.882, cut-off = 30). SBCT might be a valuable tool for bedside assessment of respiratory function in patients with COVID-19 pneumonia and might be considered as an early clinical sign of impending respiratory deterioration.

Remote Assessment of Lung Disease and Impact on Physical and Mental Health (RALPMH): Protocol for a Prospective Observational Study

BACKGROUND

Chronic lung disorders like chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF) are characterized by exacerbations. They are unpleasant for patients and sometimes severe enough to cause hospital admission and death. Moreover, due to the COVID-19 pandemic, vulnerable populations with these disorders are at high risk, and their routine care cannot be done properly. Remote monitoring offers a low cost and safe solution for gaining visibility into the health of people in their daily lives, making it useful for vulnerable populations.

OBJECTIVE

The primary objective is to assess the feasibility and acceptability of remote monitoring using wearables and mobile phones in patients with pulmonary diseases. The secondary objective is to provide power calculations for future studies centered around understanding the number of exacerbations according to sample size and duration.

METHODS

Twenty participants will be recruited in each of three cohorts (COPD, IPF, and posthospitalization COVID). Data collection will be done remotely using the RADAR-Base (Remote Assessment of Disease And Relapse) mobile health (mHealth) platform for different devices, including Garmin wearable devices and smart spirometers, mobile app questionnaires, surveys, and finger pulse oximeters. Passive data include wearable-derived continuous heart rate, oxygen saturation, respiration rate, activity, and sleep. Active data include disease-specific patient-reported outcome measures, mental health questionnaires, and symptom tracking to track disease trajectory. Analyses will assess the feasibility of lung disorder remote monitoring (including data quality, data completeness, system usability, and system acceptability). We will attempt to explore disease trajectory, patient stratification, and identification of acute clinical events such as exacerbations. A key aspect is understanding the potential of real-time data collection. We will simulate an intervention to acquire responses at the time of the event to assess model performance for exacerbation identification.

RESULTS

The Remote Assessment of Lung Disease and Impact on Physical and Mental Health (RALPMH) study provides a unique opportunity to assess the use of remote monitoring in the evaluation of lung disorders. The study started in the middle of June 2021. The data collection apparatus, questionnaires, and wearable integrations were setup and tested by the clinical teams prior to the start of recruitment. While recruitment is ongoing, real-time exacerbation identification models are currently being constructed. The models will be pretrained daily on data of previous days, but the inference will be run in real time.

CONCLUSIONS

The RALPMH study will provide a reference infrastructure for remote monitoring of lung diseases. It specifically involves information regarding the feasibility and acceptability of remote monitoring and the potential of real-time data collection and analysis in the context of chronic lung disorders. It will help plan and inform decisions in future studies in the area of respiratory health.

TRIAL REGISTRATION

ISRCTN Registry ISRCTN16275601; https://www.isrctn.com/ISRCTN16275601.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

PRR1-10.2196/28873.

Prediction models for mechanical ventilation and outcome in Guillain-Barré syndrome

Various prediction models have been formulated to predict the need for mechanical ventilation (MV). In this study, we compare the sensitivity and specificity of Erasmus GBS Respiratory Insufficiency Score (EGRIS) and Sharshar score with single breath count (SBC) at 2 Hz to assess their usefulness in predicting MV and functional outcome. The primary outcome was prediction of MV and relative usefulness of all three models based on sensitivity and specificity. The secondary outcome was functional recovery at 6 months using the cut off points for MV and functional outcome at 6months was assessed using Hughes scale and categorized as good (<2) and poor (≥2). The median age was 30 years, and 64 (69.6%) were males. The sensitivity and specificity of EGRIS score was 78.1% and 67.2%, Sharshar score was 75.0% and 64.1%, and SBC at 2 Hz was 78.1% and 75.0%. The area under the receiver operating curves was maximum for SBC at 2 Hz (0.86) compared to other models, although insignificant. EGRIS score < 5 had better functional recovery compared to those with score ≥ 5 (66% vs 34%, p = 0.001). Similarly, in Sharshar score, 23/59 (39%) with score ≥ 4 had good recovery compared to 36 (61%) with score < 4 (p = 0.01). All the three models have comparable predictive values for MV. Outcome prediction is the best with EGRIS.

Muscle Strength and Physical Performance in Patients Without Previous Disabilities Recovering From COVID-19 Pneumonia

ABSTRACT

In this cross-sectional study, we evaluated skeletal muscle strength and physical performance (1-min sit-to-stand and short physical performance battery tests), dyspnea, fatigue, and single-breath counting at discharge from a postacute COVID department, in patients recovering from COVID-19 pneumonia who had no locomotor disability before the infection.Quadriceps and biceps were weak in 86% and 73% of the patients, respectively. Maximal voluntary contraction for quadriceps was 18.9 (6.8) kg and for biceps 15.0 (5.5) kg (i.e., 54% and 69% of the predicted normal value, respectively). The number of chair rises in the 1-min sit-to-stand test was 22.1 (7.3 corresponding to 63% of the predicted normal value), whereas the short physical performance battery score was 7.9 (3.3 corresponding to 74% of the predicted normal value). At the end of the 1-min sit-to-stand test, 24% of the patients showed exercise-induced desaturation. The single-breath counting count was 35.4 (12.3) corresponding to 72% that of healthy controls. Mild-to-moderate dyspnea and fatigue were found during activities of daily living (Borg scale score, median value = 0.5 [0-2] and 1 [0-2]) and after the 1-min sit-to-stand (Borg scale score, median value = 3 [2-5] and 1 [0-3]). Significant correlations were observed between muscle strength and physical performance indices (R = 0.31-0.69).The high prevalence of impairment in skeletal muscle strength and physical performance in hospitalized patients recovering from COVID-19 pneumonia without previous locomotor disabilities suggests the need for rehabilitation programs after discharge.

Peak expiratory flow and the single-breath counting test as markers of respiratory function in patients with myasthenia gravis

INTRODUCTION

Myasthenia gravis (MG) is an antibody-mediated autoimmune disease characterised by fluctuating, fatigable muscle weakness, frequently involving bulbar and respiratory muscles. Considering the severity of respiratory involvement in MG, routine evaluation of respiratory function is essential. The aim of this study was to identify a useful clinical marker of respiratory involvement in patients with MG.

METHODS

We performed an observational study of patients with MG. All cases were evaluated with the single-breath counting test, peak expiratory flow (PEF), a modified Medical Research Council dyspnoea scale (mMRC), and a neck strength assessment. The results of these parameters were correlated with forced vital capacity (FVC), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP).

RESULTS

The study included 45 patients with MG: 2 patients classified as grade I on the Myasthenia Gravis Foundation of America classification at the time of evaluation, 35 classified as grade II, 7 classified as grade III, and one classified as grade IV. Positive correlations were found between single-breath counting test scores and FVC values (r = 0.57, p = .000), and between PEF and FVC values (r = 0.76, p = .000). Severity of dyspnoea according to the mMRC scale showed a negative correlation with FVC values (r = -0.31, p = .03). PEF also showed a significant correlation with MEP (r = 0.51, p = .002).

CONCLUSIONS

PEF, the single-breath counting test, and the mMRC scale are useful measures for evaluating respiratory function in patients with MG.

An Italian Guidance Model for the Management of Suspected or Confirmed COVID-19 Patients in the Primary Care Setting

An outbreak of Severe Acute Respiratory Syndrome Coronavirus 2 started in China's Hubei province at the end of 2019 has rapidly become a pandemic. In Italy, a great number of patients was managed in primary care setting and the role of general practitioners and physicians working in the first-aid emergency medical service has become of utmost importance to coordinate the network between the territory and hospitals during the pandemic. Aim of this manuscript is to provide a guidance model for the management of suspected, probable, or confirmed cases of SARS-CoV-2 infection in the primary care setting, from diagnosis to treatment, applying also the recommendations of the Italian Society of General Medicine. Moreover, this multidisciplinary contribution would analyze and synthetize the preventive measures to limit the spread of SARS-CoV-2 infection in the general population as well as the perspective for vaccines.

Discharge in Pandemic: Suspected Covid-19 patients returning to the Emergency Department within 72 hours for admission

INTRODUCTION

Coronavirus disease 2019 (Covid-19) has led to unprecedented healthcare demand. This study seeks to characterize Emergency Department (ED) discharges suspected of Covid-19 that are admitted within 72 h.

METHODS

We abstracted all adult discharges with suspected Covid-19 from five New York City EDs between March 2nd and April 15th. Those admitted within 72 h were then compared against those who were not using descriptive and regression analysis of background and clinical characteristics.

RESULTS

Discharged ED patients returning within 72 h were more often admitted if suspected of Covid-19 (32.9% vs 12.1%, p < .0001). Of 7433 suspected Covid-19 discharges, the 139 (1.9%) admitted within 72 h were older (55.4 vs. 45.6 years, OR 1.03) and more often male (1.32) or with a history of obstructive lung disease (2.77) or diabetes (1.58) than those who were not admitted (p < .05). Additional associations included non-English preference, cancer, heart failure, hypertension, renal disease, ambulance arrival, higher triage acuity, longer ED stay or time from symptom onset, fever, tachycardia, dyspnea, gastrointestinal symptoms, x-ray abnormalities, and decreased platelets and lymphocytes (p < .05 for all). On 72-h return, 91 (65.5%) subjects required oxygen, and 7 (5.0%) required mechanical ventilation in the ED. Twenty-two (15.8%) of the study group have since died.

CONCLUSION

Several factors emerge as associated with 72-h ED return admission in subjects suspected of Covid-19. These should be considered when assessing discharge risk in clinical practice.

Assessment of voice, speech and communication changes associated with cervical spinal cord injury

BACKGROUND

Respiratory muscle impairment following cervical spinal cord injury (CSCI) may lead to reduced voice function, although the individual variation is large. Voice problems in this population may not always receive attention since individuals with CSCI face other, more acute and life-threatening issues that need/receive attention. Currently there is no consensus on the tasks suitable to identify the specific voice impairments and functional voice changes experienced by individuals with CSCI.

AIMS

To examine which voice/speech tasks identify the specific voice and communication changes associated with CSCI, habitual and maximum speech performance of a group with CSCI was compared with that of a healthy control group (CG), and the findings were related to respiratory function and to self-reported voice problems.

METHODS & PROCEDURES

Respiratory, aerodynamic, acoustic and self-reported voice data from 19 individuals (nine women and 10 men, aged 23-59 years, heights = 153-192 cm) with CSCI (levels C3-C7) were compared with data from a CG consisting of 19 carefully matched non-injured people (nine women and 10 men, aged 19-59 years, heights = 152-187 cm).

OUTCOMES & RESULTS

Despite considerable variability of performance, highly significant differences between the group with CSCI and the CG were found in maximum phonation time, maximum duration of breath phrases, maximum sound pressure level and maximum voice area in voice-range profiles (all p = .000). Subglottal pressure was lower and phonatory stability was reduced in some of the individuals with CSCI, but differences between the groups were not statistically significant. Six of 19 had voice handicap index (VHI) scores above 20 (the cut-off for voice disorder). Individuals with a vital capacity below 50% of the expected for an equivalent reference individual performed significantly worse than participants with more normal vital capacity. Completeness and level of injury seemed to impact vocal function in some individuals.

CONCLUSIONS & IMPLICATIONS

A combination of maximum performance speech tasks, respiratory tasks and self-reported information on voice problems help to identify individuals with reduced voice function following CSCI. Early identification of individuals with voice changes post-CSCI, and introducing appropriate rehabilitation strategies, may help to minimize development of maladaptive voice behaviours such as vocal strain, which can lead to further impairments and limitations to communication participation.

Correlation of single-breath count test and neck flexor muscle strength with spirometry in myasthenia gravis

INTRODUCTION

Although formal spirometry is the gold standard for monitoring respiratory function in patients with myasthenia gravis (MG), such testing is often delayed or unavailable. There is a need for a simple bedside test that can accurately measure respiratory function.

METHODS

We conducted a prospective, cross-sectional, single-blind study in adults with acetylcholine receptor antibody positive MG. Participants performed the single breath count test (SBCT) and underwent manual muscle strength testing, and a respiratory therapist performed spirometry blinded to SBCT and strength results.

RESULTS

Thirty-one patients, aged 57 ± 19 years participated. SBCT showed significant correlations with forced vital capacity (FVC), negative inspiratory force, and neck flexor strength (P < 0.01). FVC showed significant correlation with neck flexor strength (P = 0.02) but no correlation with shoulder abductor strength.

CONCLUSIONS

These data suggest that the SBCT and neck flexor strength testing are valuable tools for bedside assessment of respiratory function in MG patients.

Outcome of Guillain-Barre syndrome patients with respiratory paralysis

BACKGROUND AND AIMS

To evaluate the outcome of patients with Guillain -: Barre syndrome (GBS) having respiratory failure treated with modified intubation policy.

DESIGN AND METHODS

Consecutive patients with GBS having single breath count below 12 and respiratory rate >30/min were included and their clinical details noted. The patients were intubated and mechanically ventilated (MV) if their PaO2 was <60 mmHg on venturi mask, PaCo2 > 50 mmHg or pH < 7.3. Their electrophysiological subtypes and complications were noted. The hospital mortality and 3 months outcome were compared in MV and those could be managed without MV even with respiratory compromise.

RESULTS

Out of 369 patients, 102 (27.6%) patients had respiratory compromise who were included in this study. Of the patients with respiratory compromise, 44 (43.1%) were intubated and mechanically ventilated after a median of 4 days of hospitalization. The median duration of MV was 21 (range 1-88) days. The patients with autonomic dysfunction (56.8% vs. 19%), facial weakness (78% vs. 36.2%), bulbar weakness (81.8% vs. 31%), severe weakness (63.8% vs. 31%) and high transaminase level (47.7% vs. 25.9%) needed MV more frequently. In our study, 6.8% patients died and 26.6% had poor outcome which was similar between MV and non-MV patients. The MV patients had longer hospitalization and more complications compared with non-MV group.

CONCLUSION

In GBS patients with respiratory compromise, conservative intubation does not increase mortality and disability.

Single breath counting for the evaluation of pediatric respiratory function: derivation of a "normogram"

Single breath counting (SBC) is the measurement of how far an individual can count in cadence with a metronome set at 2 beats per second in a normal speaking voice following a maximal effort inhalation. Previous work has demonstrated that it correlates well with standard measures of pulmonary function. The objective of this study is to derive a "normogram" of healthy children showing the expected SBC value as a function of easily measured physiologic parameters (age, gender, height, and weight). This was a prospective observational study of a convenience sample of healthy children presenting for well-child checks or non-respiratory complaints at a large tertiary care center. Correlation was determined by the Pearson's product correlation coefficient (r) and r (2) determined as a measure of shared variance. Multiple regression analysis was performed on demographic data to determine a best linear fit with calculation of the coefficient of determination (R (2)). A total of 105 children served as the basis for analysis; 54 (51.4 %) were male and average age was 9.7 (median 10, range 3-15) years. For both males and females, height correlated most strongly with SBC score (r = 0.730 and 0.725, respectively). In both genders, height alone accounted for more than 50 % of the observed variance in the results (r (2) = 0.533 and 0.526, respectively). Breath counting, an easy to perform test that appears to correlate well with standard measures of pulmonary function and shows promise for measuring asthma severity in children. We present an equation for predicting normal results (a "normogram").

Dysphonia associated with the use of inhaled corticosteroids

PURPOSE OF REVIEW

This article discusses the relationship between inhaled corticosteroids and dysphonia, with discussion of the therapeutic use of inhaled steroids in laryngeal disease and a review of negative laryngeal effects of this class of medication in patients with reactive airway disease.

RECENT FINDINGS

Although prescribed for their anti-inflammatory effects (predominantly for pulmonary disease and less often for laryngeal conditions), corticosteroid inhalers can cause laryngeal inflammation. This may relate to chemical irritation from the inhaler itself as well as fungal inflammation related to opportunistic candidiasis that may accompany inhaler use. Patients who suffer from dysphonia because of inhaler use may improve if switched to another inhaler. Studies suggest that ciclesonide metered-dose inhaler may have less oropharyngeal deposition and therefore be associated with reduced oropharyngeal candidiasis and dysphonia compared with other inhaled corticosteroids.

SUMMARY

Corticosteroid inhalers are a common cause of dysphonia and their use should be investigated in any patient with laryngeal complaints.

Noninvasive bedside assessment of acute asthma severity using single-breath counting

OBJECTIVE

The single-breath counting (SBC) method for assessment of asthma exacerbation severity has been evaluated in adults during exacerbations and in pediatric patients during routine settings. Single-breath counting has not been evaluated in children during exacerbations. We sought to assess criterion validity and responsiveness of SBC with percent-predicted FEV1 (%FEV1) and the Pediatric Respiratory Assessment Measure (PRAM), a validated acute asthma severity score.

METHODS

We prospectively enrolled subjects aged 7 to 17 years with acute asthma exacerbations. Single-breath counting, %FEV1, and PRAM were obtained before treatment and 2 hours after initiating therapy. Multivariable linear regression models were used to examine associations of pretreatment SBC with %FEV1 and PRAM (criterion validity) and 2-hour change of these measures (responsiveness). With a 2-sided α of 0.05, SBC SD of 8.5, and 90% power to detect an adjusted R of greater than 0.36 for SBC with each outcome measure, a minimum sample of 20 participants was necessary.

RESULTS

From June to November 2011, 51 participants were enrolled, with median (interquartile range) age of 8.46 years (6.92-11.4 years); male sex, n = 40 (78%); and African American race, n = 33 (64%). Before treatment, 42 (92%) were able to successfully perform SBC, and 24 (51%) %FEV1. Median pretreatment SBC obtained was 16 (10-24); %FEV1, 50 (26-71); and PRAM, 5 (1-5).

CONCLUSIONS

Single-breath counting demonstrates modest criterion validity for predicting the pretreatment PRAM score and a trend for predicting %FEV1. Single-breath counting does not appear to be responsive to change of these measures in response to treatment and has limited validity as a measure of acute asthma severity.

Simple bedside predictors of mechanical ventilation in patients with Guillain-Barre syndrome

OBJECTIVE

The objective of the study is to develop and validate a predictor score for assessing the requirement of mechanical ventilation (MV) in patients with Guillain-Barre syndrome (GBS).

STUDY DESIGN

The study was conducted in patients admitted with GBS in neurointensive care unit in a tertiary care hospital. The demographic, clinical factors, electrophysiological, and spirometric data of all consecutive patients were prospectively collected. The study was undertaken in 2 stages. In the first stage, data were collected for development of a predictor score. In the second stage, the score developed was validated on a separate set of patient data.

RESULTS

The data collected were compared between the 2 groups (ventilated vs nonventilated). On univariate analysis, time taken to reach maximum deficit, neck weakness, bulbar weakness, facial weakness, single breath count (SBC), forced vital capacity, and phrenic nerve latency predicted the need for MV. On multivariate analysis, only neck weakness, bulbar weakness, SBC, and forced vital capacity were independent predictors of MV. There was a good correlation between SBC and the spirometric tests and phrenic nerve distal motor latency, as reflected in receiver operating characteristics curve. The predictor score developed using the regression coefficient of independent predictors showed that the best cutoff score for prediction of ventilation was 60 (sensitivity, 0.95; 1--specificity, 0.065). Internal cross validation of the neck weakness, SBC, and bulbar palsy (NSB) score showed good correlation (Pearson R = 0.76; P = .00). There was no statistically significant difference between predicted and observed outcomes (sensitivity, 95%; specificity, 93%).

CONCLUSION

Several independent risk factors were found to predict the requirement for MV in patients with GBS at admission. However, after scoring and analyzing them, it was found that combining a few of them was more useful to predict the need for MV. A model using NSB score, developed using clinical variables, accurately predicted the requirement of MV. In addition, among the NSB score parameters, simple bedside SBC could adequately assess the adequacy of vital capacity.

Medical aspects of bio-terrorism

INTRODUCTION

Bioterrorism is a terrorist action involving the intentional release or dissemination of a biological warfare agent (BWA), which includes some bacteria, viruses, rickettsiae, fungi or biological toxins. BWA is a naturally occurring or human-modified form that may kill or incapacitate humans, animals or plants as an act of war or terrorism. BWA is a weapon of choice for mass destruction and terrorism, because of the incubation period, less effective amount than chemical warfare agents, easily distribution, odorless, colorless, difficult to detect, no need of specialized equipment for production and naturally distribution which can easily be obtained. BWA may be disseminating as an aerosol, spray, explosive device, and by food or water.

CLASSIFICATION

Based on the risk for human health, BWAs have been prioritized into three categories of A, B and C. Category A includes microorganisms or toxins that easily spread, leading to intoxication with high death rates such as Anthrax, Botulism, Plague, Smallpox, Tularemia and Viral hemorrhagic fevers. Category B has lower toxicity with wider range, including Staphylococcal Entrotoxin type B (SEB), Epsilon toxin of Clostridium perfringens, Ricin, Saxotoxins, Abrin and Trichothecene mycotoxins. The C category includes emerging pathogens that could also be engineered for mass spread such as Hanta viruses, multidrug-resistant tuberculosis, Nipah virus, the tick-borne encephalitis viruses, hemorrhagic fever viruses and yellow fever. CLINICAL MANIFESTATIONS OF BIOTOXINS IN HUMAN: Clinical features and severity of intoxication depend on the agent and exposed dose, route of entry, individual variation and environmental factors. Onset of symptoms varies from 2-24 h in Ricin to 24-96 h in Botulism. Clinical manifestations also vary from irritation of the eyes, skin and mucus membranes in T2 toxin to an acute flaccid paralysis of bilateral cranial nerve impairment of descending manner in botulism. Most of the pyrogenic toxins such as SEB produce the same signs and symptoms as toxic shock syndrome including a rapid drop in blood pressure, elevated temperature, and multiple organ failure.

MANAGEMENT

There is no specific antidote or effective treatment for most of the biotoxins. The clinical management is thus more supportive and symptomatic. Fortunately vaccines are now available for most of BWA. Therefore, immunization of personnel at risk of exposure is recommended.

CONCLUSION

Biotoxins are very wide and bioterrorism is a heath and security threat that may induce national and international problems. Therefore, the security authorities, health professional and even public should be aware of bioterrorism.

Single-breath counting: a pilot study of a novel technique for measuring pulmonary function in children

INTRODUCTION

Although peak expiratory flow rate is the conventional way to measure asthma severity in adults, its use is problematic in children because it is effort dependent. Forced expiratory volume in 1 second (FEV₁) and the ratio of FEV₁ to forced vital capacity (FEV₁/FVC) are more accurate, but generally not available in the emergency department (ED). A better test is needed. Single-breath counting (SBC) is the measurement of how far an individual can count in a normal speaking voice after a maximal effort inhalation. The count is in cadence to a metronome set at 2 beats per second. Previous work has suggested that SBC correlates with standard measures of pulmonary function in adults. However, it has never been tested in children.

OBJECTIVES

The aims of this study are to determine if SBC can be easily performed by children and to assess the correlation between SBC and standard measures of pulmonary function in a pediatric population.

METHODS

This was a prospective observational study of a convenience sample of children presenting to the pulmonary clinic for scheduled pulmonary function testing (PFT). Peak expiratory flow rate, FEV₁, FVC, forced expiratory flow 25% to 75%, and FEV₁/FVC were measured and recorded. After PFT, subjects were asked to perform SBC. Three attempts were allowed, and the average was recorded. Correlation was determined by the Pearson coefficient.

RESULTS

Sixty-seven children (ages 5-18 years, 64% male) were enrolled. All were able to understand and complete the testing. Indications for PFT included asthma and/or allergies (n = 44), cystic fibrosis (n = 9), and other chronic diseases (n = 14). The correlations (r) of SBC to peak expiratory flow rate, FEV₁, FVC, forced expiratory flow 25% to 75%, and FEV₁/FVC were 0.55, 0.66, 0.71, 0.44, and -0.29, respectively (P < .05 for all results).

CONCLUSION

Single-breath counting is easy to perform in children, seems to correlate well with standard measures of pulmonary function, and shows promise for measuring asthma severity in children. Further work to define the range of reference SBC values (as a function of age and/or body size) and an evaluation of the utility of SBC in an ED population of acute asthmatics is indicated.

Comparison of peak expiratory flow rate with speaking time in ED patients presenting with acute exacerbation of asthma

Thirty-six patients with a history of asthma who presented to an emergency department (ED) with an acute exacerbation were studied prospectively to determine if a correlation existed between peak expiratory flow rate (PEFR) and speaking time. Each patient listened to an instructional audiotape on the proper method of counting and then maximally inhaled and counted until it became necessary to take a second breath. This represented the patient's "speaking time" in seconds. A PEFR was then obtained using a hand-held peak flow meter. The speaking time and PEFR were measured before and after each nebulized albuterol treatment. A total of 169 pairs of pretreatment and posttreatment PEFR and speaking time measurements were obtained. Regression analysis of the PEFR and speaking time demonstrated the PEFR can be predicted by the speaking time with statistical significance (P < .0001). The regression analysis equation was: peak flow (L/min) = 114.8 +/- (17.6 x speaking time).