Sniff test: does what we measure at the nose reflect what happens in the chest wall?

Nasal pressure measured during sniff (SNIP) is a technically simple voluntary test. Since the contraction of the diaphragm expands the abdomen, the volume variation during sniff manoeuvre should therefore be predominantly abdominal in order to be considered a specific index of diaphragm strength. We aimed to verify if and how SNIP varied according to thoraco-abdominal volume variations. We measured abdominal volume variations, using opto-electronic plethysmography, during quiet breathing (ABQB) and sniff manoeuvres (ABSN) in supine position on 30 patients (age: 42; FVC:47.5%; FEV1:30%) on the waiting list for lung transplant. SNIP was measured simultaneously with ABSN. 68 sniff were analysed and classified into 4 groups according to ABSN: 16 with thoracic paradox, 24 predominantly abdominal, 16 predominantly thoracic and 12 with abdominal paradox. By definition ABSN was different (p<0.001) among the 4 groups, whereas ABQB (~75%; p=0.373) and SNIP (~53 cmH2O, p= 0.792) were similar (figure 1). SNIP did not change with the different thoraco-abdominal strategies. The diaphragm was not weak and leaded inspiration, therefore ABSN varied because the patients misperformed the manoeuvre. In order to not misunderstand the clinical significance of a sniff test, care should be paid also in thoraco-abdominal movement because SNIP, per se, cannot differentiate between thoracic or diaphragmatic manoeuvre with the risk to lose its specificity

Spontaneous breathing pattern as respiratory functional outcome in children with spinal muscular atrophy (SMA)

Introduction: SMA is characterised by progressive motor and respiratory muscle weakness. We aimed to verify if in SMA children 1)each form is characterized by specific ventilatory and thoracoabdominal pattern(VTAp) during quiet breathing(QB); 2)VTAp is affected by salbutamol therapy, currently suggested as standard treatment, or by the natural history(NH) of SMA; 3)the severity of global motor impairment linearly correlates with VTAp. Materials and methods: VTAp was analysed on 32 SMA type I (SMA1, the most severe form), 51 type II (SMA2, the moderate), 8 type III (SMA3, the mildest) and 20 healthy (HC) using opto-electronic plethysmography. Spirometry, cough and motor function were measured in a subgroup of patients. Results: In SMA1, a normal ventilation is obtained in supine position by rapid and shallow breathing with paradoxical ribcage motion. In SMA2, ventilation is within a normal range in seated position due to an increased respiratory rate(p0.05) while tachypnea occurred in type I NH. A linear correlation(p<0.001) was found between motor function scales and VTAp. Conclusion: A negative or reduced %ΔVRC,P, indicative of ribcage muscle weakness, is a distinctive feature of SMA1 and SMA2 since infancy. Its quantitative assessment represents a non-invasive, non-volitional index that can be obtained in all children, even uncollaborative, and provides useful information on the action of ribcage muscles that are known to be affected by the disease. Low values of motor function scales indicate impairment of motor but also of respiratory function

Intellectual abilities, language comprehension, speech, and motor function in children with spinal muscular atrophy type 1

Background: Spinal muscular atrophy (SMA) is a chronic, neuromuscular disease characterized by degeneration of spinal cord motor neurons, resulting in progressive muscular atrophy and weakness. SMA1 is the most severe form characterized by significant bulbar, respiratory, and motor dysfunction. SMA1 prevents children from speaking a clearly understandable and fluent language, with their communication being mainly characterized by eye movements, guttural sounds, and anarthria (type 1a); severe dysarthria (type 1b); and nasal voice and dyslalia (type 1c). The aim of this study was to analyze for the first time cognitive functions, language comprehension, and speech in natural history SMA1 children according to age and subtypes, to develop cognitive and language benchmarks that provide outcomes for the clinical medication trials that are changing SMA1 course/trajectory. Methods: This is a retrospective study including 22 children with SMA1 (10 affected by subtype 1a-1b: AB and 12 by 1c: C) aged 3–11 years in clinical stable condition with a coded way to communicate “yes” and “no”. Data from the following assessments have been retrieved from patient charts: one-dimensional Raven test (RCPM), to evaluate cognitive development (IQ); ALS Severity Score (ALSSS) to evaluate speech disturbances; Brown Bellugy modified for Italian standards (TCGB) to evaluate language comprehension; and Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) to assess motor functioning. Results: SMA 1AB and 1C children were similar in age, with the former characterized by lower CHOP-INTEND scores compared to the latter. All 22 children had collaborated to RCPM and their median IQ was 120 with no difference (p = 0.945) between AB and C. Global median score of the speech domain of the ALSSS was 5; however, it was 2 in AB children, being significantly lower than C (6.5, p < 0.001). TCGB test had been completed by 13 children, with morphosyntactic comprehension being in the normal range (50). Although ALSSS did not correlate with both IQ and TCGB, it had a strong (p < 0.001) correlation with CHOP-INTEND described by an exponential rise to maximum. Conclusions: Although speech and motor function were severely compromised, children with SMA1 showed general intelligence and language comprehension in the normal range. Speech impairment was strictly related to global motor impairment

Rib Cage Deformities Alter Respiratory Muscle Action and Chest Wall Function in Patients with Severe Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is an inherited connective tissue disorder characterized by bone fragility, multiple fractures and significant chest wall deformities. Cardiopulmonary insufficiency is the leading cause of death in these patients.Seven patients with severe OI type III, 15 with moderate OI type IV and 26 healthy subjects were studied. In addition to standard spirometry, rib cage geometry, breathing pattern and regional chest wall volume changes at rest in seated and supine position were assessed by opto-electronic plethysmography to investigate if structural modifications of the rib cage in OI have consequences on ventilatory pattern. One-way or two-way analysis of variance was performed to compare the results between the three groups and the two postures. compared to predicted values, on condition that updated reference equations are considered. In both positions, ventilation was lower in OI patients than control because of lower tidal volume (p<0.01). In contrast to OI type IV patients, whose chest wall geometry and function was normal, OI type III patients were characterized by reduced (p<0.01) angle at the sternum (pectus carinatum), paradoxical inspiratory inward motion of the pulmonary rib cage, significant thoraco-abdominal asynchronies and rib cage distortions in supine position (p<0.001).In conclusion, the restrictive respiratory pattern of Osteogenesis Imperfecta is closely related to the severity of the disease and to the sternal deformities. Pectus carinatum characterizes OI type III patients and alters respiratory muscles coordination, leading to chest wall and rib cage distortions and an inefficient ventilator pattern. OI type IV is characterized by lower alterations in the respiratory function. These findings suggest that functional assessment and treatment of OI should be differentiated in these two forms of the disease