The Hypoxic Training index (HTi) provides an objective measure of the hypoxic stress delivered during the Intermittent Hypoxic Training (IHT) session, compared to simple recording the inhaled fraction of oxygen (FiO2). HTi provides a figure (index) of dosage received by the individual at the end of the session. [1] Knowledge of HTi can therefore be used to alter the training regime for different individuals, compensating for individual variability, and can be used in scientific studies to ensure that subject exposure was correctly controlled.
Tissue hypoxia develops only when arterial oxygen saturation (SpO2) drops to 90% or below. This is due to the oxyhaemoglobin dissociation curve. Saturations above 90% produce very little effect or decrease of arterial oxygen partial pressure (PaO2). In order to obtain consistent and comparable values of HTi for different individuals the following conditions should be stipulated:
The resulting formula for calculating HTi is:
where:
HTi : Hypoxic Training index,
t : period of time, and
SpO2 (t) : SpO2 (%), arterial oxygen saturation value measured at one-second intervals.
This image shows a typical SpO2 curve during a full biofeedback-controlled IHT session. (FiO2 is altered automatically using biofeedback controlled hypoxicator to attain and sustain the desired SpO2 target value.)
Advanced biofeedback controlled hypoxicators are capable of adjusting the oxygen concentration in the inhaled hypoxic air automatically. This automatic biofeedback control allows targeting of the desired SpO2, compensating for individual variability. Software is also available [2] to calculate HTi based on readings from a USB connected Pulse Oximeter.
Hypoxia is a condition in which the body or a region of the body is deprived of adequate oxygen supply at the tissue level. Hypoxia may be classified as either generalized, affecting the whole body, or local, affecting a region of the body. Although hypoxia is often a pathological condition, variations in arterial oxygen concentrations can be part of the normal physiology, for example, during hypoventilation training or strenuous physical exercise.
Pulse oximetry is a noninvasive method for monitoring a person's oxygen saturation. Though its reading of peripheral oxygen saturation (SpO2) is not always identical to the more desirable reading of arterial oxygen saturation (SaO2) from arterial blood gas analysis, the two are correlated well enough that the safe, convenient, noninvasive, inexpensive pulse oximetry method is valuable for measuring oxygen saturation in clinical use.
The Fick principle states that blood flow to an organ can be calculated using a marker substance if the following information is known:
Altitude training is the practice by some endurance athletes of training for several weeks at high altitude, preferably over 2,400 metres (8,000 ft) above sea level, though more commonly at intermediate altitudes due to the shortage of suitable high-altitude locations. At intermediate altitudes, the air still contains approximately 20.9% oxygen, but the barometric pressure and thus the partial pressure of oxygen is reduced.
An altitude tent is a sealed tent used to simulate a higher altitude with reduced oxygen. Living or training at altitude causes the body to adapt to the lower oxygen content by producing more oxygen-carrying red blood cells and hemoglobin, thus causing the body to adapt to the higher altitude and enhancing performance when returning to a lower altitude. Mountain climbers can use them to avoid altitude sickness, and athletes can use them to enhance performance at lower altitudes.
High-altitude pulmonary edema (HAPE) is a life-threatening form of non-cardiogenic pulmonary edema that occurs in otherwise healthy people at altitudes typically above 2,500 meters (8,200 ft). However, cases have also been reported between 1,500–2,500 metres or 4,900–8,200 feet in more vulnerable subjects.
Cerebral hypoxia is a form of hypoxia, specifically involving the brain; when the brain is completely deprived of oxygen, it is called cerebral anoxia. There are four categories of cerebral hypoxia; they are, in order of severity: diffuse cerebral hypoxia (DCH), focal cerebral ischemia, cerebral infarction, and global cerebral ischemia. Prolonged hypoxia induces neuronal cell death via apoptosis, resulting in a hypoxic brain injury.
Hypoxemia is an abnormally low level of oxygen in the blood. More specifically, it is oxygen deficiency in arterial blood. Hypoxemia has many causes, often, and can cause tissue hypoxia as the blood is not supplying enough oxygen to the body.
A CO-oximeter is a device that measures the oxygen carrying state of hemoglobin in a blood specimen, including oxygen-carrying hemoglobin (O2Hb), non-oxygen-carrying but normal hemoglobin (HHb), as well as the dyshemoglobins such as carboxyhemoglobin (COHb) and methemoglobin (MetHb). The use of 'CO' rather than 'Co' or 'co' is more appropriate since this designation represents a device that measures carbon monoxide (CO) bound to hemoglobin, as distinguished from simple oximetry which measures hemoglobin bound to molecular oxygen—O2Hb—or hemoglobin capable of binding to molecular oxygen—HHb. Simpler oximeters may report oxygen saturation alone, i.e. the ratio of oxyhemoglobin to total 'bindable' hemoglobin. CO-oximetry is useful in defining the causes for hypoxemia, or hypoxia,.
Inert gas asphyxiation is a form of asphyxiation which results from breathing a physiologically inert gas in the absence of oxygen, or a low amount of oxygen, rather than atmospheric air. Examples of physiologically inert gases, which have caused accidental or deliberate death by this mechanism, are argon, helium, nitrogen and methane. The term "physiologically inert" is used to indicate a gas which has no toxic or anesthetic properties and does not act upon the heart or hemoglobin. Instead, the gas acts as a simple diluent to reduce oxygen concentration in inspired gas and blood to dangerously low levels, thereby eventually depriving all cells in the body of oxygen.
Freediving blackout, breath-hold blackout or apnea blackout is a class of hypoxic blackout, a loss of consciousness caused by cerebral hypoxia towards the end of a breath-hold dive, when the swimmer does not necessarily experience an urgent need to breathe and has no other obvious medical condition that might have caused it. It can be provoked by hyperventilating just before a dive, or as a consequence of the pressure reduction on ascent, or a combination of these. Victims are often established practitioners of breath-hold diving, are fit, strong swimmers and have not experienced problems before. Blackout may also be referred to as a syncope or fainting.
The simple face mask (SFM) is a basic disposable mask, made of clear plastic, to provide oxygen therapy for patients who are experiencing conditions such as chest pain, dizziness, and minor hemorrhages. This mask is only meant for patients who are able to breathe on their own, but who may require a higher oxygen concentration than the 21% concentration found in ambient air. Patients who are unable to breathe on their own are placed on a medical ventilator instead. The simple face mask can deliver higher flow rates than nasal cannula for an FiO2 of 40–60% oxygen. Nasal cannula and simple face masks are described as low flow delivery systems.
Latent hypoxia occurs when a diver under pressure has a tissue oxygen concentration that is sufficient to support consciousness at that pressure, but insufficient at surface pressure. This problem is associated with freediving blackout and the presence of hypoxic breathing gas mixtures in underwater breathing apparatus, particularly in diving rebreathers.
Masimo is an American manufacturer of noninvasive patient monitoring technologies based in Irvine, California. The company sells more pulse oximetry to hospitals than any other company. Masimo was founded in 1989 by electrical engineer Joe Kiani, who was later joined by fellow engineer Mohamed Diab.
A hypoxicator is a medical device intended to provide a stimulus for the adaptation of an individual's cardiovascular system by means of breathing reduced oxygen hypoxic air and triggering mechanisms of compensation. The aim of intermittent hypoxic training or hypoxic therapy conducted with such a device is to obtain benefits in physical performance and wellbeing through improved oxygen metabolism.
Intermittent hypoxic training (IHT), also known as intermittent hypoxic therapy technique aimed at improving human performance by way of adaptation to reduced oxygen.
Environmental oxygenation can be important to the sustainability of a particular ecosystem. Insufficient oxygen may occur in bodies of water such as ponds and rivers, tending to suppress the presence of aerobic organisms such as fish. Deoxygenation increases the relative population of anaerobic organisms such as plants and some bacteria, resulting in fish kills and other adverse events. The net effect is to alter the balance of nature by increasing the concentration of anaerobic over aerobic species.
Oxygen saturation is the fraction of oxygen-saturated hemoglobin relative to total hemoglobin in the blood. The human body requires and regulates a very precise and specific balance of oxygen in the blood. Normal arterial blood oxygen saturation levels in humans are 95–100 percent. If the level is below 90 percent, it is considered low and called hypoxemia. Arterial blood oxygen levels below 80 percent may compromise organ function, such as the brain and heart, and should be promptly addressed. Continued low oxygen levels may lead to respiratory or cardiac arrest. Oxygen therapy may be used to assist in raising blood oxygen levels. Oxygenation occurs when oxygen molecules enter the tissues of the body. For example, blood is oxygenated in the lungs, where oxygen molecules travel from the air and into the blood. Oxygenation is commonly used to refer to medical oxygen saturation.
Hypoxia refers to low oxygen conditions. Normally, 20.9% of the gas in the atmosphere is oxygen. The partial pressure of oxygen in the atmosphere is 20.9% of the total barometric pressure. In water, oxygen levels are much lower, approximately 7 ppm 0.0007% in good quality water, and fluctuate locally depending on the presence of photosynthetic organisms and relative distance to the surface.
Intermittent hypoxia (also known as episodic hypoxia) is an intervention in which a person or animal undergoes alternating periods of normoxia and hypoxia. Normoxia is defined as exposure to oxygen levels normally found in earth's atmosphere (~21% O2) and hypoxia as any oxygen levels lower than those of normoxia. Normally, exposure to hypoxia is negatively associated to physiological changes to the body, such as altitude sickness. However, when used in moderation, intermittent hypoxia may be used clinically as a means to alleviate various pathological conditions.
