ELMO, a new helmet interface for CPAP to treat COVID-19-related acute hypoxemic respiratory failure outside the ICU: a feasibility study

Tomaz, Betina Santos; Gomes, Gabriela Carvalho; Lino, Juliana Arcanjo; Menezes, David Guabiraba Abitbol de; Soares, Jorge Barbosa; Furtado, Vasco; Soares Júnior, Luiz; Farias, Maria do Socorro Quintino; Lima, Debora Lilian Nascimento; Pereira, Eanes Delgado Barros; Holanda, Marcelo Alcantara

doi:10.36416/1806-3756/e20210349

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Jornal Brasileiro de Pneumologia

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ORIGINAL ARTICLE • J. bras. pneumol. 48 (01) • 2022 • https://doi.org/10.36416/1806-3756/e20210349 copy

ELMO, a new helmet interface for CPAP to treat COVID-19-related acute hypoxemic respiratory failure outside the ICU: a feasibility study

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Objective:

To assess the feasibility of using a new helmet interface for CPAP, designated ELMO, to treat COVID-19-related acute hypoxemic respiratory failure (AHRF) outside the ICU.

Methods:

This was a proof-of-concept study involving patients with moderate to severe AHRF secondary to COVID-19 admitted to the general ward of a public hospital. The intervention consisted of applying CPAP via the ELMO interface integrated with oxygen and compressed air flow meters (30 L/min each) and a PEEP valve (CPAP levels = 8-10 cmH₂O), forming the ELMOcpap system. The patients were monitored for cardiorespiratory parameters, adverse events, and comfort.

Results:

Ten patients completed the study protocol. The ELMOcpap system was well tolerated, with no relevant adverse effects. Its use was feasible outside the ICU for a prolonged amount of time and was shown to be successful in 60% of the patients. A CPAP of 10 cmH₂O with a total gas flow of 56-60 L/min improved oxygenation after 30-to 60-min ELMOcpap sessions, allowing a significant decrease in estimated FIO₂ (p = 0.014) and an increase in estimated PaO₂/FIO₂ ratio (p = 0.008) within the first hour without CO₂ rebreathing.

Conclusions:

The use of ELMOcpap has proven to be feasible and effective in delivering high-flow CPAP to patients with COVID-19-related AHRF outside the ICU. There were no major adverse effects, and ELMO was considered comfortable. ELMOcpap sessions significantly improved oxygenation, reducing FIO₂ without CO₂ rebreathing. The overall success rate was 60% in this pilot study, and further clinical trials should be carried out in the future.

(ClinicalTrials.gov identifier: NCT04470258 [http://www.clinicaltrials.gov/])

Keywords:
Pneumonia; SARS-CoV-2; COVID-19; Respiratory protective devices; Continuous positive airway pressure; Noninvasive ventilation

Characteristic	Patient
Characteristic	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10
Age, years	76	70	71	77	42	75	37	54	60	39
Sex	F	F	M	M	M	M	M	M	M	M
Weight, kg	72	58	63	66	110	64	93	65	75	105.2
Height, cm	154	158	164	156	170	159	182	163	174	172
BMI, kg/m²	30.2	23.2	23.4	27.1	38.0	25.7	28.0	24.9	24.7	35.6
SOFA score at study entry	2	2	2	2	2	4	2	2	2	2
APACHE II score at study entry	11	11	15	10	5	12	4	8	4	5
Smoking history	Yes	Yes	No	Yes	No	Yes	No	No	Yes	No
Comorbidities	Diabetes Obesity	Hypertension Diabetes	Hypertension Diabetes	Hypertension	Obesity	Hypertension	-	Hypertension	Hypertension Diabetes	-
Symptoms before hospital admission	Cough Dyspnea Loss of appetite Adynamia	Cough Dyspnea Fever	Dyspnea Fever	Cough Fever Loss of appetite Headache	Cough Dyspnea Fever Nausea Vomiting	Cough Dyspnea Fever Odynophagia Coryza	Cough Fever	Cough Dyspnea	Cough Dyspnea Fever Loss of appetite Myalgia	Fever Adynamia
Extension of pulmonary impairment on CT	-	> 75%	> 75%	50-75%	> 75%	50-75%	-	50-75%	> 75%	> 75%
1st arterial blood gas analysis after hospital admission
pH	7.51	7.50	7.50	7.52	7.51	7.48	7.46	7.52	7.49	7.49
PaO₂, mmHg	51	68	68	75	167	91	60	89	74	79
PaCO₂, mmHg	35	33	41	35	37	34	41	34	41	39
HCO₃, mEq/L	28.5	28.5	28.5	28.5	28.5	28.5	29.2	27.8	28.5	29.7
BE, mEq/L	4.9	2.5	8.8	2.8	6.2	1.8	4.9	2.0	7.2	5.9
SaO₂, %	89	95	95	96	100	98	92	98	96	97
Lactate, mmol/L	1.4	2.0	1.3	1.5	1.1	1.8	1.3	2.0	2.0	1.4
Oxygen therapy at hospital admission	RV 8 L/min	NC 5 L/min	RV 8 L/min	RV 8 L/min	RV 10 L/min	RV 9 L/min	NC 4 L/min	RV 15 L/min	NC 6 L/min	RV 10 L/min
Laboratory findings at hospital admission
White blood cell count/mm³	10,780	8,351	19,340	14,630	10,730	13,610	10,870	14,950	7,931	12,900
Lymphocyte count/mm³	757	1,338	1,355	586	537	681	1,088	1,346	795	1,419
Hemoglobin level, g/dL	11.6	13.3	12.3	13.5	13.8	14.7	13.4	13.5	14.4	13.9
Hematocrit, %	36.6	40.9	36.8	41.4	41.2	41.5	39.0	39.3	45.5	41.9
Band cell count/mm³	107	83	580	0	0	136	0	149	0	0
Segmented cell count/mm³	9,809	6,513	16,825	13,313	9,764	12,249	9,130	12,857	6,582	10,707
Platelet count/mm³	211,500	168,200	187,000	283,000	237,800	128,500	287,500	301,900	232,500	190,000
CRP, mg/dL	27.2	3.8	20.4	7.9	11.4	3.4	14.3	5.4	4.5	5.35
Urea, mg/dL	24	29	64	43	37	44	41	63	44	35
Creatinine, mg/dL	0.3	0.5	1.4	0.9	0.7	0.7	0.6	1.1	0.7	0.7
D-dimer, μg/mL	> 20	0.42	1.38	0.7	1.28	1.32	0.74	0.73	1	1.69
Fibrinogen, mg/dL	221	-	687	-	-	-	-	-	-	-
AST, U/L	64	33	54	55	37	109	24	34	40	98
ALT, U/L	99	30	47	26	47	29	26	45	75	216
CPK, U/L	42	52	185	28	18	1,393	35	173	198	37
LDH, U/L	548	247	386	373	401	1,503	405	312	371	545
Ferritin, ng/mL	> 1,500	280	> 1,500	> 1,500	> 1,500	> 1,500	1,307	-	1,091	766
Days of symptoms preceding ELMOcpap use, n	7	13	4	13	13	10	15	17	11	11

Variable	Patient
Variable	P1	P2	P3	P4	P5	P6	P7	P8	P9	P10
Total number of sessions	2	5	11	7	17	1	1	1	2	14
CPAP level, cmH₂O	10 [10-12]	8 [8-10]	10 [8-10]	10 [10-10]	10 [8-10]	8 [8-8]	10 [8-10]	8 [8-8]	8 [8-8]	10 [10-10]
Total therapy time, min	100	440	1,230	880	1,980	60	40	20	180	2,640
ROX index within 2 h after the 1st session	6.2	5.2	5.2	7.7	8.2	5.2	7.5	1.9	16.0	13.0
VAS comfort score	5	8	7	9	9	-	3	0	10	8
Main adverse effects	-	Regurgitation	Dry mouth	Eye irritation	Cervical and armpit discomfort	-	-	-	Cough	-
Number of days of utilization	2	2	5	4	7	1	1	1	2	5
ELMOcpap use outcome^b	Failure	Success	Success	Success	Success	Failure	Failure	Failure	Success	Success
Total length of hospital stay before first ELMOcpap session, days	0	8	4	2	4	3	3	11	1	3
Total length of hospital stay, days	7	14	13	13	19	24	7	58	5	13
Clinical course assessed just before first ELMOcpap session	Worsening	Stable	Stable	Stable	Stable	Worsening	Improving	Worsening	Improving	Stable
Orotracheal intubation after ELMOcpap use	Yes	No	No	No	No	Yes	No	Yes	No	No
Outcome	Death	Discharge	Discharge	Discharge	Discharge	Death	Discharge	Discharge	Discharge	Discharge

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E-mail: jbp@sbpt.org.br

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[1] Correspondence to:
Betina Santos Tomaz. Rua Leda Porto Freire, 200, apto. 1503 Torre B, Parque Iracema, CEP 60824-030, Fortaleza, CE, Brasil. Tel.: 55 85 3366-8208. E-mail: betina.stufc@gmail.com