IT202000025813A1 - METHOD FOR EARLY IDENTIFYING ASYMPTOMATIC AND PAUCI-SYMPTOMATIC COVID-19 POSITIVE - Google Patents

Description

Title: ? METHOD FOR EARLY IDENTIFYING ASYMPTOMATIC AND PAUCI-SYMPTOMATIC COVID-19 POSITIVE ?

Description

Field of the technique of the invention

The present invention relates to a method for the early diagnosis of COVID-19 infection, which allows to identify asymptomatic and pauci-symptomatic COVID-19 subjects and in general those who are affected by Coronavirus viral pathologies (large family of respiratory viruses ).

State of art

To diagnose a Covid-19 (SARS-CoV-2) infection, the nose-throat molecular swab is currently used on both symptomatic and asymptomatic patients, ie. all those who, while not showing clinical signs of the disease, are part of the community? at risk, have contacted Covid-19 positive subjects or come from high-risk areas or who have gone to the hospital for other types of tests. The swab, however?, has drawbacks since? ? positive only during the development of the infection. Furthermore, the nose-throat swab has two variables: the first? that of the operator who does it and who could make mistakes, the second ? that of those who process the sample collected in the laboratory. As for the samples, up to 30% pu? be a false negative, but with possible human errors the false negative rate goes up to 50%.

For diagnostic insights, in cases with suspected Coronavirus pneumonia, the use of high-resolution computed tomography (HRCT) is envisaged. considered the most technical accurate.

The main problem, though?, ? that many asymptomatic are not even traced, since unaware of being healthy carriers of the infection. In fact, it is assumed that the real number of infected is much greater than those diagnosed. In addition, Covid-19, in addition to being more? contagious (thirty times closer to its receptor) than the SARS and MERS viruses, is it? sneaky for another biological reason, not clarified, which differentiates it from all other respiratory viruses, not only from coronavirus, but also from the flu virus, why? ? contagious (that is, an infected subject is infectious) when the symptoms have not yet manifested themselves, while the contagiousness? (linked to the viral load) decays in the symptomatic patient.

In the very first stages of the infection, the asymptomatic or the pauci-symptomatic are generally aferetic (or with a small rise in body temperature), eupnoic (or slightly tachypneic) and, above all, all characterized by high %SaO2 or PaO2, i.e. higher than one's age range? compared to healthy subjects.

Furthermore, from the first days of infection, the entry of COVID-19 (and in general of all Coronaviruses through the pulmonary epithelium) causes an accumulation of a powerful vasoconstrictor (angiotensin II), which causes pulmonary vasoconstriction and a consequent slowing of pulmonary circulation.

Summary of the invention

The present invention relates to a method for early identification of asymptomatic and paucisymptomatic COVID-19 positive subjects, using changes in the measurements of physiological and blood chemistry parameters, the variation of which? caused by the entry into the body, through the pulmonary epithelium, of COVID-19 and coronaviruses in general. The changes in the measurements of these parameters are due to the slowing down of the pulmonary circulation and what? of the Pulmonary Blood Flow which, again with this method, is objectively quantified. The measurements of the physiological and blood chemistry parameters of interest can be obtained in a fast and minimally invasive way using a metabolimeter (or using a trolley or metabolic system or a capnograph), a blood gas analyzer (Blood Gas Analyzer) for blood gas analysis and a pulse oximeter ( pulse oximeter) digital or forehead and optionally a cardiac output meter.

An object of the present invention ? a method for the early diagnosis of Covid-19 infection which draws inspiration from the evidence, detected by the present inventor, that in a very early phase of the infection, when the disease has not still manifested for which the symptoms are not present, an increase in blood oxygen saturation (%SaO2), a decrease in ventilation (Ve) and a decrease in the exhaled volume of CO2 per minute (VCO2) occur in the infected subject, all parameters whose measurements vary according to the reduction of Pulmonary Blood Flow (FPs), quantified with an algorithm, applied to blood parameters and VCO2. Said parameters can be measured on a subject by means of simple-to-use and low-cost instrumentation, such as blood gas analyzers and metabolizers and optionally a cardiac output measurer. These instruments can be present in any analysis laboratory, doctor's surgery and hospital.

A further object of the present invention ? a simplified method for the early diagnosis of COVID-19 based on the evaluation of the variation of the measures of physiological parameters, such as the volume of carbon dioxide exhaled over time (VCO2), ventilation (Ve) and the percentage of O2 saturation (%SpO2 ) all determined by the decrease in Pulmonary Blood Flow (FPs) (calculated with a predictive equation), a decrease caused, in turn, by the COVID-19 infection. The VCO2 and the Ve are measurable for example with a trolley or metabolic system, a capnograph or a metabolimeter, while the %SpO2 ? measurable with a digital or frontal pulse oximeter (oximeter) (a function that can in turn be present in the metabolimeter). All these tools can be present in any laboratory, in medical clinics, gyms or even with private users, which makes this method a valid preventive tool.

These and other objects, as outlined in the appended claims, will be described in the continuation of the description. The text of the claims must be considered included in the description for the purpose of assessing the sufficiency of the description.

Detailed description of the invention

The parameters described in this patent application are expressed in the following dimensions:

- FPs (pulmonary blood flow) in L/min

- VCO2 (expired volume of CO2 over time) in L/min - Qt (cardiac output) in L/min of blood

- PCO2v (partial pressure of venous blood CO2) and PCO2a (partial pressure of arterial blood CO2) in mmHg

- [HCO3-]v (bicarbonate anion concentration in venous blood) and [HCO3-]a (bicarbonate anion concentration in arterial blood) in mmol/L

- ? = capital greek letter used to define a total flow

- ?CO2(e) (total molar flow rate of exhaled CO2) in mmol/min

- dimensionless FPs/Qt ratio, correlated to pulmonary vascular resistance (the more FPs is less than Qt, therefore the ratio is less than 1, the higher the pulmonary vascular resistances are

- %SaO2 percentage of oxygen saturation in arterial blood, measured by blood gas analysis

- %SpO2 percentage of oxygen saturation in arterial blood, measured by oximeter

- Ve (volume of air exhaled over time) in L/min. With the term ?about? in the present description a variation of ?2% is meant.

According to a first aspect, the present invention relates to a method for identifying asymptomatic and pauci-symptomatic COVID-19 positive subjects, which comprises the following steps:

a) making available a set of physiological parameters of a subject at rest, in which said parameters were measured at a time t1, said physiological parameters being selected from exhaled volume of CO2 per minute (VCO2), cardiac output (Qt), venous blood CO2 partial pressure (PCO2v), arterial blood CO2 partial pressure (PCO2a), venous blood bicarbonate anion concentration ([HCO3-]v), arterial blood bicarbonate anion concentration ([HCO3-]a ), percent arterial hemoglobin saturation for O2 (%SaO2) and ventilation (Ve);

b) calculate the pulmonary blood flow (FPst1) from said set of parameters of phase a) according to the following algorithm A:

(TO)

<in which>

calculate the FPst1/Qtt1 ratio and detect the measurement of %SaO2t1 and Vet1;

c) making available a second set of physiological parameters of a subject at rest, in which said parameters were measured at a time t2 following t1 of 72 hours or less, said physiological parameters being chosen from exhaled volume of CO2 per minute ( VCO2), cardiac output (Qt), venous blood CO2 partial pressure (PCO2v), arterial blood CO2 partial pressure (PCO2a), venous blood bicarbonate anion concentration ([HCO3-]v), bicarbonate anion concentration in arterial blood ([HCO3-]a), percent arterial hemoglobin saturation for O2 (%SaO2) and ventilation (Ve);

d) calculating the pulmonary blood flow (FPst2) from said set of parameters of phase c) according to algorithm A of phase b), calculating the FPst2/Qtt2 ratio and detecting the measurement of %SaO2t2 and Vet2;

e) compare the calculated FPst1/Qtt1 and FPst2/Qtt2 values with a reference FPs/Qt value, and compare the FPst1 and FPst2 values with a reference FPs value, where:

i) if the following conditions occur simultaneously

- the FPst1/Qtt1 ratio, calculated in phase b) ? substantially equal to the ratio FPst2/Qtt2, calculated in phase d) and if FPst1 ? substantially equal to FPst2 and therefore the relationship FPst2/FPst1 ? about equal to 1, e

- are the %SaO2 values measured in phases b) and d) within the normal range for your age range? and remain substantially the same, e

- the measurements of Ve taken in phases b) and d) remain substantially the same,

then the subject? COVID-19 negative;

ii) if the following conditions occur simultaneously

- the FPst1/Qtt1 ratio and the calculated FPst1 value are 15-20% lower than the reference FPs/Qt and FPs value and

- the value of %SaO2 ? higher than the normal value for one's age range, then the subject has a first probability? to be COVID-19 positive;

iii) if the following conditions occur simultaneously

- the FPst1/Qtt1 ratio? greater than the ratio FPst2/Qtt2 and their delta ? between 0.585 and 0.085 and - FPst1 ? substantially greater than FPst2 so much that the ratio FPst2/FPst1 ? less than 0.85, or when FPst1 - FPst2 ? 1 L/min e

- the value of %SaO2t2 ? higher than the value of %SaO2t1 and ? higher than the normal value for one's age range? And

- the value of Vet2 ? lower than Vet1,

then the subject has a second probability? to be COVID-19 positive, in which he dictates the second probability? ? greater than said first probability.

Pulmonary blood flow (FPs) ? expressed in L/min and ? calculated with the algorithm A.

The VCO2 (expressed in L/min) can? be derived by a measurement with a metabolic cart or system, a capnograph, or a metabolimeter.

Qt (expressed in L/min) can? be measured by various methods known and reported in the literature, including Doppler ultrasound, pulse pressure methods, impedance cardiography, ultrasound dilution, electrical cardiometry, nuclear magnetic resonance, and dye dilution method. If FPs (derived with algorithm A) ? greater than Qt means that the measure of Qt ? incorrect (underestimated). Therefore, Algorithm A immediately reveals a cardiac output (Qt) measurement error.

%SaO2 ? obtained from blood gas analysis.

Ve (expressed in L/min) ? measured for example with a trolley or metabolic system, a capnograph or a metabolimeter.

Venous blood CO2 partial pressure (PCO2v), arterial blood CO2 partial pressure (PCO2a), venous blood bicarbonate anion concentration ([HCO3-]v), arterial blood bicarbonate anion concentration ([HCO3-]a ), can be obtained by blood gas analysis.

When is the subject in the condition of first probability? found in step ii), the positivity? from COVID-19 can be confirmed with the test at time t2 of step iii).

When the subject is in the condition of second probability? found in step iii), the positivity? from COVID-19 can be confirmed by molecular swab and/or high-resolution computed tomography.

The evaluation of step iii) ? applicable to a subject that is not ? suffering from altitude sickness and/or high-altitude pulmonary edema (HAPE High-Altitude Pulmonary Edema) caused by high-altitude hypoxia or not? affected by gaseous embolism from scuba diving and has not taken vasoconstrictor drugs, such as acetazolamide, (already established cases of vasoconstriction/obstruction in which FPst1 > FPst2).

The above reference values of the FPs/Qt ratio and of the FPs value vary according to the health status of the subject with possible or suspected COVID-19 infection.

In particular said reference values

I am:

- an FPs/Qt value between 0.97 and 0.985 and an FPs value between 4.00 and 4.6 for a normal subject or a subject with class I chronic heart failure (CHF) (NYHA classification) ;

- an FPs/Qt value between 0.90 and 0.97 and an FPs value between pi? of 4.6 and 5.49 for a subject with class II CHF (NYHA classification);

- an FPs/Qt value lower than 0.90 and an FPs value greater than or equal to 5.5 for a subject with class III CHF (NYHA classification);

- an FPs/Qt value between 0.82 and 0.9 and an FPs value between 4 and 4.6 for a subject with Class I pulmonary hypertension (PI) (WHO/NYHA classification);

- an FPs/Qt value between 0.60 and 0.81 and an FPs value between 3.6 and 3.99 for a subject with Class II pulmonary hypertension (PI) (WHO/NYHA classification);

- an FPs/Qt value between 0.40 and 0.59 and an FPs value between 2.4 and 3.599 for a subject with Class III pulmonary hypertension (PI) (WHO/NYHA classification);

- an FPs/Qt value between 0.65 and 0.85 and an FPs value of less than 2.4 for a subject with Class IV pulmonary hypertension (PI) and/or Class IV CHF.

As mentioned above, the normal values of %SaO2 depend on the age range? of the subject. Table 1 below shows these values according to age:

Table 1 ? Percentage blood oxygen saturation values (%SaO2 or %SpO2) in healthy subjects according to the age range?

The method described above requires, as mentioned, parameters that can be obtained using various normally hospital instruments, including a trolley or metabolic system, a capnograph or a metabolimeter, blood gas analysis equipment and, as regards the cardiac output Qt, using complex methodologies and sometimes invasive. Taking into account that paucious-symptomatic subjects and above all asymptomatic ones, are not aware of their condition and therefore autonomously and voluntarily would not undergo any test to detect COVID-19, with serious danger of spreading the virus in the population,? It is important in this phase of the COVID-19 pandemic that there is an accurate and continuous control over time of one's state of health by the population, also carried out comfortably at home.

There is therefore the need to also make available a method that allows continuous control over time, non-invasive, for home use, at low cost and which promptly signals to the subject that, while not showing clinical signs of the disease, his or her body are developing the infection.

The inventor of this patent application? been able to develop predictive equations that allow the calculation of a basal blood Pulmonary Flow (FPsb), which constitutes a fundamental starting point of reference and of absolute necessity? and an FPs-nth (FPsn), always calculated with the same predictive equation. The value of FPs-nth compared to the baseline value of FPs (FPsn/FPsb), detects the variations of this parameter, becoming a first and important alarm signal.

The following predictive equation (B) ? been obtained by combining three different predictive equations, which, in turn, were obtained from the interpolation of tabulated data deriving from measurements of biochemical parameters on a population of subjects and has a significance? high stat:

FPs = 4.7893.ln[0.4304.(?CO2(e)-1.005.?CO2(e)<0.9703>)<2 >+ 11.285. (?CO2(e) -1.005.?CO2(e)<0.9703>) 3.3912] ? 9.4075

(B)

From the above it can be seen that the Pulmonary Blood Flow (FPs) in a subject can be calculated with excellent approximation through the sole measurement of the VCO2, easily obtainable by means of a metabolimeter, a low-cost instrument, potentially available to any laboratory or clinic, as well as? of a private entity.

Therefore a further embodiment of the present invention is a simplified method for early detection of asymptomatic and paucisymptomatic COVID-19 positive subjects, which includes the following steps:

I) making available physiological parameters of a negative Covid-19 subject at rest, in which said parameters were measured at a time t1, said physiological parameters being the exhaled volume of CO2 per minute (VCO2), %SpO2, and of Ve , said values being baseline values of said subject;

II) from the baseline VCO2 value according to step I), obtain FPst1 with the following algorithm (B):

FPs = 4.7893.ln[0.4304.(?CO2(e)-1.005.?CO2(e)<0.9703>)<2 >+ 11.285. (?CO2(e) -1.005.?CO2(e)<0.9703>) 3.3912] ? 9.4075

(B) <in> <whose>

III) making available a value of %SpO2, of VCO2 and of Ve of said subject at rest, said values being obtained at a time t2 subsequent to time t1;

IV) from the VCO2 value of phase III), obtain FPst2 with algorithm (B):

FPs = 4.7893.ln[0.4304.(?CO2(e)-1.005.?CO2(e)<0.9703>)<2 >+ 11.285. (?CO2(e) -1.005.?CO2(e)<0.9703>) 3.3912] ? 9.4075

(B) in which

V) compare the value of FPst2, %SpO2 and Ve according to phases III) and IV) with the respective baseline values of phases I) and II) in which:

i) if the following conditions occur simultaneously

- the FPst2 value of phase IV) ? equal to the respective FPst1 value of phase II), and therefore the FPst2/FPst1 ratio ? about equal to 1,

- the % SpO2 detected in phases I) and III) ? substantially the same,

- Ve detected in phases I) and III) ? substantially the same,

then the subject? COVID-19 negative;

ii) if the following conditions occur simultaneously

- the FPst2 value of phase IV) ? lower than the respective FPst1 value of phase II) so that the FPst2/FPst1 ratio ? less than 0.77,

- the %SpO2 value of phase III) ? higher than the respective %SpO2 value of phase I) and ? higher than the normal value for your age group,

- the Ve value of phase III) ? lower than the respective Ve value of phase I),

- the decrease of FPst2 ? equal to or greater than 1 from your baseline FPst1 value,

then the subject has a probability? greater than 50% of being COVID-19 positive;

VI) if the subject ? COVID-19 negative according to step i), optionally repeat steps III), IV) and V) to one or more times tn following time t2, for example at regular intervals.

To ascertain the causes of the sudden decrease in FPs will it be necessary? subject the subject to molecular testing and / or high-resolution computed tomography or, in the case of negativity? to COVID-19, perform a diagnostic test for pulmonary thromboembolism. AND? It is also important to verify that the subject is not suffering from altitude sickness and/or high-altitude pulmonary edema (HAPE High-Altitude Pulmonary Edema) caused by high-altitude hypoxia or gas embolism from scuba diving and has not taken any medications vasoconstrictors, such as acetazolamide.

Preferably, if the subject ? COVID-19 positive, will the method include? the following next step:

VII) monitor the condition of the subject by repeating phases III), IV) and V) in successive times and at substantially regular or predefined intervals.

There? allow? doctors to intervene appropriately with the right drugs and their dosages.

The following table indicates the correspondence between the FPs, SaO2%, VCO2 and Ve values in some subject populations:

PLACEBO at rest and normoxia

FPs at 4.15 L/min ? SaO2% ? 97.4% ? <VCO>2= 330 mL/min ? Ve=11.2 L/min

Acetazolamide at rest and normoxia

FPs at 2.71 L/min ? SaO2% ? 97.9% ? <VCO>2= 300 mL/min ? Ve=11.0 L/min

PLACEBO at rest and hypoxia

FPs at 5.33 L/min ? SaO2% ? 82%? <VCO>2= 440 mL/min ? Ve=16.8 L/min

Acetazolamide at rest and hypoxia

FPs at 4.25 L/min ? SaO2% ? 86%? <VCO>2= 410 mL/min ? Ve=16.6 L/min.

These data prove that in the presence of vasoconstriction (induced by acetazolamide) there is a decrease in FPs and consequently an increase in blood oxygen saturation, a decrease in exhaled VCO2 and a decrease in Ve (ventilation). This ? the condition that occurs in the first days of contagion from COVID-19. In fact, the entry of COVID-19 (and in general of all Coronaviruses through the pulmonary epithelium) causes an accumulation of a potent vasoconstrictor (angiotensin II), causing pulmonary vasoconstriction, which in turn determines a decrease in FPs and the resulting changes in VCO2, %SaO2 (or %SpO2) and Ve as indicated above. Furthermore, it should be emphasized that influenza viruses do not have the same infectious mechanism as coronaviruses, therefore they do not produce the same effects on FPs. Consequently, when is it? in the presence of influenza viruses, the symptoms of which can partially overlap with those of Covid-19, this method makes it possible to selectively diagnose a coronavirus infection thus preventing, in the case of influenza, an unnecessary use of the molecular test to Covid-19 and, pending the outcome, to uselessly quarantine an entire family unit.

From the above it can be deduced that the method of the present invention at least partially achieves the intended aims, since:

- allows you to verify, in a hospital center or medical analysis laboratories or doctor's surgeries, a sudden decrease in Pulmonary Blood Flow in asymptomatic and pauci-symptomatic patients, detectable through algorithm A and the concomitant increase in %SaO2 and decrease in Ve , presumably caused by Coronavirus (COVID-19) infection;

- allows an immediate and timely indication of the presence of a vasoconstriction/obstruction of the Pulmonary Blood Flow in asymptomatic and pauci-symptomatic, through the verification of a sudden decrease in the Pulmonary Blood Flow, detectable through the algorithm B applied directly on the VCO2 , and a concomitant increase in %SpO2 and a decrease in Ve; to check for the presence of COVID-19 infection will it be necessary? perform a molecular test and/or high-resolution computed tomography;

- allows continuous control over time, non-invasive and without burdening health facilities, why? the test ? executable by the subject in his own home;

- allows an assessment of the severity? of the pathology in progress (due to the entity of the obstructed vascular bed) depending on the decrease more? or less conspicuous in Pulmonary Blood Flow and FPs/Qt ratio (related to pulmonary vascular resistance);

- in patients at risk of contagion from COVID-19 due to belonging to a community? (eg school, elderly hospitalized in nursing homes-RSA, sports, business, activities open to the public, etc.) allows you to trace the undeclared population of the asymptomatic and pauci-symptomatic population, immediately isolate only the infected and offer the opportunity to undergo antiviral therapy successfully, since? this therapy? effective only in the early stage of the infection;

- allows you to selectively diagnose a COVID-19 infection, which is based on a different infectious mechanism than a normal flu, thus preventing an unnecessary use of the swab;

- allows public health surveillance for COVID-19 using the simplified method (with algorithm B) applied to widely used instruments also for domestic use;

- allows for large-scale prevention of the spread of viral diseases such as Coronaviruses;

- prevents the development and aggravation of the pathology, thanks to timely notification to the subject and, possibly, to the local social-health districts of the infection in progress, and thanks to the consequent therapeutic intervention;

- allows an appropriate choice of drugs and relative doses appropriate to the individual case;

- allows for the monitoring of the clinical course and the evaluation of the response to the therapeutic treatment; - allows you to follow and monitor the course of long-term COVID-19 sequelae in healed patients, for the recovery of their quality of life and the care of the same;

- allows only positive COVID-19 to be isolated in quarantine and not all that large part of the negative COVID-19 population, which could normally carry out its activities, but which with territorial or national lockdowns, is prevented from them, causing serious damage economic to individuals and to the whole nation;

- ? not at all or minimally invasive;

- ? not so expensive.

Claims (5)

CLAIMS 1. Method for identifying asymptomatic and pauci-symptomatic COVID-19 positive subjects, which includes the following phases: a) making available a set of physiological parameters of a subject at rest, in which said parameters were measured at a time t1, said physiological parameters being selected from exhaled volume of CO2 per minute (VCO2), cardiac output (Qt), venous blood CO2 partial pressure (PCO2v), arterial blood CO2 partial pressure (PCO2a), venous blood bicarbonate anion concentration ([HCO3-]v), arterial blood bicarbonate anion concentration ([HCO3-]a ), percent arterial hemoglobin saturation for O2 (%SaO2) and ventilation (Ve); b) calculate the pulmonary blood flow (FPst1) from said set of parameters of phase a) according to the following algorithm A: (A) <in which > calculate the FPst1/Qtt1 ratio and detect the measurement of %SaO2t1 and Vet1; c) making available a second set of physiological parameters of a subject at rest, in which said parameters were measured at a time t2 following t1 of 72 hours or less, said physiological parameters being chosen from exhaled volume of CO2 per minute ( VCO2), cardiac output (Qt), venous blood CO2 partial pressure (PCO2v), arterial blood CO2 partial pressure (PCO2a), venous blood bicarbonate anion concentration ([HCO3-]v), bicarbonate anion concentration in arterial blood ([HCO3-]a), percent arterial hemoglobin saturation for O2 (%SaO2) and ventilation (Ve); d) calculating the pulmonary blood flow (FPst2) from said set of parameters of phase c) according to algorithm A of phase b), calculating the FPst2/Qtt2 ratio and detecting the measurement of %SaO2t2 and Vet2; e) compare the calculated FPst1/Qtt1 and FPst2/Qtt2 values with a reference FPs/Qt value, and compare the FPst1 and FPst2 values with a reference FPs value, where: i) if the following conditions occur simultaneously - the FPst1/Qtt1 ratio, calculated in phase b) ? substantially equal to the ratio FPst2/Qtt2, calculated in phase d) and if FPst1 ? substantially equal to FPst2 and therefore the relationship FPst2/FPst1 ? about equal to 1, e - are the %SaO2 values measured in phases b) and d) within the normal range for your age range? and remain substantially the same, e - the measurements of Ve taken in phases b) and d) remain substantially the same, then the subject? COVID-19 negative; ii) if the following conditions occur simultaneously - the FPst1/Qtt1 ratio and the calculated FPst1 value are 15-20% lower than the reference FPs/Qt and FPs value and - the value of %SaO2 ? higher than the normal value for one's age range, then the subject has a first probability? to be COVID-19 positive; iii) if the following conditions occur simultaneously - the FPst1/Qtt1 ratio? greater than the ratio FPst2/Qtt2 and their delta ? between 0.585 and 0.085 and - FPst1 ? substantially greater than FPst2 so much that the ratio FPst2/FPst1 ? less than 0.85, or when FPst1 - FPst2 ? 1 L/min e - the value of %SaO2t2 ? higher than the value of %SaO2t1 and ? higher than the normal value for one's age range? And - the value of Vet2 ? lower than Vet1, then the subject has a second probability? to be COVID-19 positive, in which he dictates the second probability? ? greater than said first probability. 2. Method according to claim 1, wherein said reference values in step e) are: - an FPs/Qt value between 0.97 and 0.985 and an FPs value between 4.00 and 4.6 for a normal subject or a subject with class I chronic heart failure (CHF) (NYHA classification) ; - an FPs/Qt value between 0.90 and 0.97 and an FPs value between pi? of 4.6 and 5.49 for a subject with class II CHF (NYHA classification); - an FPs/Qt value lower than 0.90 and an FPs value greater than or equal to 5.5 for a subject with class III CHF (NYHA classification); - an FPs/Qt value between 0.82 and 0.9 and an FPs value between 4 and 4.6 for a subject with Class I pulmonary hypertension (PI) (WHO/NYHA classification); - an FPs/Qt value between 0.60 and 0.81 and an FPs value between 3.6 and 3.99 for a subject with Class II pulmonary hypertension (PI) (WHO/NYHA classification); - an FPs/Qt value between 0.40 and 0.59 and an FPs value between 2.4 and 3.599 for a subject with Class III pulmonary hypertension (PI) (WHO/NYHA classification); - an FPs/Qt value between 0.65 and 0.85 and an FPs value of less than 2.4 for a subject with Class IV pulmonary hypertension (PI) and/or Class IV CHF. 3. Simplified method for early detection of asymptomatic and pauci-symptomatic COVID-19, which includes the following steps: I) making available physiological parameters of a negative Covid-19 subject at rest, in which said parameters were measured at a time t1, said physiological parameters being the exhaled volume of CO2 per minute (VCO2), %SpO2, and of Ve , said values being baseline values of said subject; II) from the baseline VCO2 value according to step I), obtain FPst1 with the following algorithm (B): FPs = 4.7893.ln[0.4304.(?CO2(e)-1.005.?CO2(e)<0.9703>)<2 >+ 11.285. (?CO2(e) -1.005.?CO2(e)<0.9703>) 3.3912] ? 9.4075 (B) <in which> III) making available a value of %SpO2, of VCO2 and of Ve of said subject at rest, said values being obtained at a time t2 subsequent to time t1; IV) from the VCO2 value of phase III), obtain FPst2 with algorithm (B): FPs = 4.7893.ln[0.4304.(?CO2(e)-1.005.?CO2(e)<0.9703>)<2 >+ 11.285. (?CO2(e) -1.005.?CO2(e)<0.9703>) 3.3912] ? 9.4075 (B) <in which> V) compare the value of FPst2, %SpO2 and Ve according to phases III) and IV) with the respective baseline values of phases I) and II) in which: i) if the following conditions occur simultaneously - the FPst2 value of phase IV) ? equal to the respective FPst1 value of phase II), and therefore the FPst2/FPst1 ratio ? about equal to 1, - the % SpO2 detected in phases I) and III) ? substantially the same, - if Ve detected in phases I) and III) ? substantially the same, then the subject? COVID-19 negative; ii) if the following conditions occur simultaneously - the FPst2 value of phase IV) ? lower than the respective FPst1 value of phase II) so that the FPst2/FPst1 ratio ? less than 0.77, - the %SpO2 value of phase III) ? higher than the respective %SpO2 value of phase I) and ? higher than the normal value for your age group, - the Ve value of phase III) ? lower than the respective Ve value of phase I), - the decrease of FPst2 ? equal to or greater than 1 from your baseline FPst1 value, then the subject has a probability? greater than 50% of being COVID-19 positive; VI) if the subject ? COVID-19 negative according to step i), optionally repeat steps III), IV) and V) to one or more times tn following time t2, for example at regular intervals. The method according to claim 3, comprising the following next step: VII) monitor the condition of the subject by repeating phases III), IV) and V) in successive times and at substantially regular or predefined intervals. 5. A method according to any one of claims 1 to 4, wherein said subject is not suffering from altitude sickness and/or high-altitude pulmonary edema (HAPE High-Altitude Pulmonary Edema) caused by high-altitude hypoxia or not? suffering from gas embolism from scuba diving and has not taken vasoconstrictor drugs, such as acetazolamide, or cases already? findings of vasoconstriction/obstruction in which FPst1 > FPst2.