Single breath counting as a respiratory muscle function assessment test

Background: Spirometry may be used as a surrogate marker of respiratory muscle strength in patients with neuromuscular disorders. However, it is an aerosol-generating procedure, not readily conducted during remote consultation, and its use has been limited by infection control guidance during the COVID-19 pandemic. Single breath counting (SBC) has been reported to predict vital capacity (VC). We aimed to evaluate the utility of SBC in our clinic. Method(s): We conducted an evaluation to compare SBC and VC measurements in healthy volunteers and patients with respiratory muscle weakness. To perform SBC, individuals were asked to maximally inhale and then count every second in time with a metronome from 1 to the highest number they could manage in a single breath. SBC was repeated 3 times and the mean and maximum results were recorded. Individuals performed spirometry for slow VC in accordance with ERS guidelines. Results were compared using Spearman's rank correlation coefficient. Result(s): 31 healthy controls and 18 cases were included. The correlation between VC and SBC were rho=0.697 (p<0.001) and rho=0.694 (p<0.001) for mean and maximal efforts respectively (Figure). Conclusion(s): Primary findings highlight the potential usefulness of SBC for respiratory muscle function assessment. This promising technique is simple and feasible with current infection control guidelines and may be useful in remotely conducted appointments.

Improved COVID-19 outcomes in a large non-invasive respiratory support cohort despite new variants

P217 Table 1A comparison of first and second wave characteristics, treatment and outcome data First wave Second wave Mean difference (95%CI) X2 (df) P value Age (years) 69.0 (52.0, 80.0) 62.0 (52.0, 71.0) -3.4 (-7.8 to +1.1) - 0.14 Sex: - Male - Female 49 (69.0%) 22 (31.0%) 180 (65.0%) 97 (35.0%) - 0.4 (1) 0.52 BMI (kg/m2) 28.5 (24.9, 33.6) 29.6 (24.8, 34.9) +0.6 (-1.7 to +2.9) - 0.63 Clinical Frailty Score: - 1 to 2 (fit) 18 (25.4%) 132 (47.7%) - 15.6 (5) 0.008 CT severity score - Moderate/severe - Severe 11 (29.7%) 23 (62.2%) 131 (52.2%) 113 (45.0%) - 16.0 (3) 0.0012 CRP prior to rHDU admission (mg/L) 180.6 (118.0, 210.0) 124.1 (78.1, 175.6) -44.1 (-66.9 to -21.3) - 0.0002 Spike gene testing - VOC B.1.1.7 variant - Wild-type - Ambiguous - - - 143 (67.1%) 57 (26.8%) 13 (6.1%) - - - Dexamethasone 3 (4.2%) 266 (96.0%) - 271.4 (1) <0.0001 Remdesivir 4 (5.6%) 198 (71.5%) - 100.6 (1) <0.0001 CPAP as primary respiratory support 32 (45.1%) 248 (89.5%) - 71.1 (1) <0.0001 Able to adopt semi- or full- prone position 42 (59.2%) 237 (85.6%) - 24.8 (1) <0.0001 Admission outcome (all) - Died - Discharged 36 (50.7%) 35 (49.3%) 74 (26.7%) 201 (72.5%) - 14.7 (1) 0.0001 rHDU outcome (‘For Intubation’) - Died - Off respiratory support - Intubated 0 (0.0%) 14 (41.2%) 20 (58.8%) 7 (3.3%) 152 (72.4%) 51 (24.3%) - 17.3 (2) 0.0002 ConclusionOur single centre experience shows that rHDU mortality and intubation rates have improved over time in spite of the emergence of new variants. Improvements in outcome are likely to be multi-factorial. Our data support the benefit of pharmacological COVID-19 therapies in a rHDU population as well as the use of CPAP and awake proning. Other potential causes for improved outcomes are lower serological and radiological COVID-19 severity in our wave two cohort as well as reduced rates of frailty.Referencehttps://medrxiv.org/content/10.1101/2021.03.11.21253364v1