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Home , Hyperventilation, Hypocapnia

and the body

C. Gilbert

Hyperventilation has rapid and far-ranging physiological effects via its alteration of pH and depletion of CO 2 in the body, resulting in respiratory , acute or chronic. The general effects on skeletal and smooth muscles, as well as neural tissue, are summarized. A wide variety of symptoms such as pain, tension, disturbances of consciousness, circulatory problems and cardiovascular effects can confound treatment efforts but may respond to alterations of patterns. Suggestions are given for detecting this condition.

Introduction Background Imagine the following set of symptoms reported The 'Fat folder' syndrome is one vivid description to you: episodes of light-headedness attached by Claude Lum to the so-called accompanied by cool, moist hands, pale skin, hyperventilation syndrome, indicating the perhaps some tunnel vision, , tortuous, and tortured, doctor-to-doctor path headaches, feelings of unreality, dread and followed by many individuals pursuing relief agitation; heart , uncomfortable from their problems. Each specialist performs his breathing and tender shoulder muscles. Suppose tests, finds little that is specifically diagnostic, and that medical consultation has found little of note, dutifully relays the individual on to the next but at least there is no evidence of major disease. specialist because typically, with this disorder, Where would you start? A break for lunch, symptoms come and go in many different perhaps? systems. Hyperventilation simply means breathing in Christopher Gilbert In working with such a diffuse set of PhD Social Sciences complaints spread out over many systems, a excess of the body's needs for at a and Human practitioner will naturally tend to focus on the particular moment. The need fluctuates Services, Ramapo symptom that is most familiar and easiest to continuously, and the body gets what it needs by College of New Jersey, Mahwah, handle, and may postpone dealing with the rest adjusting respiratory rate and depth. Strong, NJ 07430, USA of the picture in the hopes that perhaps vigorous breathing, no matter how fast or deep, is Correspondence everything will clear up in time, or that someone not necessarily hyperventilatory unless it is in to: C. Gilbert, else will handle the other problems. You may excess of the body's needs. 10 Wilsey Square #14, Ridgewood, receive a referral because you hold out promise of The problem in hyperventilation is not 'too NJ 07450, USA helping with the muscle pain or the headaches. much oxygen' - whatever is unabsorbed by the Manuscript But other things are probably happening as well. lungs is simply exhaled again. The problem accepted: The problem, in the example above, may comes with a deficit of CO 2. CO2 is a waste gas, a April 1998 actually be an intermittent biochemical byproduct of , primarily muscle This article was derangement brought on by insufficient carbon activity; it is given off by tissues and carried in previously published in dioxide (CO2) in the , resulting in broad the bloodstream to the lungs, to be exhaled. Journal of effects on every organ and nearly every bodily Production of CO 2 is normally in equilibrium Bodywork and system. Even though there is no clear indication with 0 2 intake. Movement Therapies 2(3): of overbreathing at that moment, it may be This equilibrium is important because CO2 has 184-191 correct to consider hyperventilation. an essential physiological function, remarkable

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considering that it's on its way to being excreted: present moment but in some other moment more it is a prime regulator of vascular tone in the associated with frustration, , or anger. In cerebral cortex, among other places. This is such a case time and place are blurred as the Nature's elegant : in a natural memory or imagination stimulates the body to environment and assuming normal physiology, prepare for action: fight, flight, or tense-freeze. CO 2 builds up in the bloodstream only with All these options require muscle contraction, breath-holding or while breathing oxygen-poor which requires oxygen, so hyperventilation air. In either case, high blood CO 2 correlates with becomes a sensible precautionary preparation. less oxygen available. Since oxygen deficit Apart from this reality-shifting effect, events () is dangerous to the brain, several actually occurring in the present moment may mechanisms combine in such a circumstance to not really require any physical action: for maintain normal brain oxygenation, and instance, when one's hypercritical supervisor is vasodilation of blood vessels is one of them. This coming to inspect your work and you are is probably due to alterations in calcium and/or preparing for a confrontation that requires only phosphorus movement through the vessel walls. words, not fists. Here there will be a discrepancy Arterial walls, when dilated, become more between the action-demands on the body and the permeable to oxygen molecules. mind's expectation of trouble. Apparently the possibility of threat of any kind, social or The loophole physical, reliably sets off physical preparation 'just in case'. Hyperventilation is part of this, The opposite condition, however, is more more for some individuals than others. Also, relevant to this article. There seems to be a there is evidence that the hyperventilation can loophole, or flaw, in the system, possibly unique easily be conditioned (Ley 1999) so that a to humans: although high CO 2 stimulates stimulus associated with potential danger will vasodilatation and increased oxygenation, a drop trigger more breathing directly, just as Pavlov's in CO 2 stimulates vasoconstriction and in fact is dogs came to salivate to the sound of a bell. said to be the 'most potent vasoconstrictive agent Hyperventilation is functional as long as known' (Raichle & Plum 1972). This other half of muscle use follows closely after; the resulting a regulatory mechanism becomes rapidly reserve of oxygen and loss of CO 2 permit a head dysfunctional as CO 2 in the blood start if danger should materialize. The regulatory drops, and that is what happens when an mechanisms for breathing probably evolved individual breathes in excess of bodily needs for without providing for the possibility that oxygen: more CO 2 is exhaled than is being hyperventilation might occur at times other than replaced. The degree of circulatory loss in the preparing for action. When emotional arousal cerebral cortex is around 2% for each I mmHg does not lead to physical action, it can leave the drop in CO 2 (Gardner 1996) This loss is brain and body impaired by alkalosis because visible to an observer if the hyperventilating is driven to a higher level than is individual's cortex happens to be uncovered at required by the situation. The muscles are the time; it has been described by neurosurgeon not generating enough CO 2 to replace what is Wilder Penfield as a blanching of the surface of being exhaled; the organism is not active when the brain. the system expects it to be. Thus body and mind Normal arterial tension can live in two different worlds, and this odd (PaCO2) is around 40 mmHg. A level of 30 mismatch can create a morass of symptoms and corresponds to pH of 7.5; this is the commonly- no end of distress (Table 1). accepted point at which mild hypocapnic symptoms are likely to begin.Twenty mmHg is Importance of pH associated with a pH of 7.6, at which symptoms will appear in almost everyone. The body takes pains to preserve a normal pH in Response to 'needs of the moment' may the body, particularly in the bloodstream, constitute one thing to the body but quite another extracellular fluids and cerebrospinal fluid. The thing to the mind, at least in human beings. For body is optimized for a pH of 7.4, slightly above instance, an individual can be mentally not in the the neutral 7.0, toward the alkaline end. This

1999 Harcourt Brace & Company Ltd Accident and Emergency Nursing (1999) 7, 130-140 131 Hyperventilation and the body

Table 1 Notable acute effects of hyperventilation

Effects on smooth muscle

Generally, vasoconstriction and spasm

Gastrointestinal: tight throat, difficulty swallowing, intestinal

Restricted circulation in cerebral cortex (leads to light-headedness, , visual disturbances)

Cold hands and feet

Impaired coronary artery blood flow

Effects on skeletal muscle

Weakness, fatigue, twitching

Heart muscle disturbance (palpitations, skipped beats, rapid pulse)

Vague shifting pains, especially around chest

Diaphragm weakness, impaired breathing

Tense or fatigued neck and shoulder muscles (from over use during thoracic breathing)

Effects on nervous system

Peripheral tingling, numbness

Hypersensitivity to lights and sounds

Faster reflexes

Enhanced sympathetic activity (more adrenaline)

Common psychological effects

Panic, fear of death

Restlessness, heightened vigilance

Time distortion, depersonalization, derealization

Misinterpretation of symptoms (catastrophic thinking, hypochondria)

supports endocrine, metabolic and other combination of high pH and low CO 2 causes maintenance operations. Deviations in pH of a certain body changes. Acute, episodic tenth of a point have noticeable consequences for hyperventilation is often associated with an the body, changing nerve conduction, the emotional crisis, either current or relived. In the diameter of blood vessels and the contractility of stereotype, hyperventilation is seen as a smooth muscle. 'attack' - dramatic and obvious, but ameliorated We can easily disrupt this balance with 2 or 3 by letting time pass or by breathing into a paper deep breaths, pH will rise from 7.4 to 7.5 or 7.6, bag. This is actually much less common than and CO 2 will fall from a normal 40 to 30 or 25 in subtle, chronic hyperventilation. In this case, less than 30 seconds (Figs 1 & 2). The symptoms are milder but more persistent;

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/ .~"~'~ CO2 45 mmHg + Vasodilatation Produced i Uxygen I-" Exhaled pH~ I @,,.~@ () r e~ttackted adequate Blood cerebral vessel circulation A diameter

CO2 30 mmHg- Vasoconstriction , /F Exhaled Excessive I-r ~ Produced pH breathing I UD !k @,,~| (alkalosis) impaired CO2 Blood cerebral vessel circulation B diameter

Fig. 1 CO2 as a regulator of cerebrovascular tone. Breathing volume determines amount of CO2 excreted per unit time; metabolic demand determines amount of CO2 produced. With CO2 production in equilibrium with CO2 excretion, all is well; pH stays at 7.4 and CO2 remains at 35-40 mmHg. However, (A) With restricted oxygen intake (breath-holding or high CO2 air), more CO2 is produced than is exhaled. CO2 rises, stimulating blood-vessel dilatation to offset danger of suffocation. (13) With hyperventilation (breathing excessive for body's needs) more CO2 is exhaled than is produced. CO2 drops, stimulating blood-vessel constriction

breathing is less obviously 'off', and the body has Hyperventilating started to compensate for the hyperventilation. (alkaline)

Effects on skeletal muscle pH 7.31 ...... / and low CO 2 affect muscle function in several ways. For one thing, the A ,0ci01>1 muscle potential threshold drops, making the 45 individual more susceptible to twitches and 40 spasms. Phosphorus tends to be lost during C02 hyperventilation, and low serum phosphorus 35 levels have been linked to skeletal muscle 30 weakness and impaired nerve conduction in general. Contractility of the diaphragm may be disrupted, which would increase the difficulty in getting a deep breath and set off urgent attempts to get more air, resulting in a 'vicious circle'. Claude Lum, a major figure in study of C hyperventilation, describes a '... specific effect Arterial diameter on facilitatory synapses involved in somatic Fig. 2 'Hyperventilating:' as breathing increases motor reflex arcs - such as tendon reflexes - beyond metabolic needs, CO2 is depleted from the body reflex time is shortened, and synaptic and alkalinity rises. Smooth muscles, such as blood vessels, are more likely to constrict. (A) = pH; (B) = CO2; transmission is accelerated' (Lure 1981). (C) = arterial diameter Moderate hyperventilation causes motor excitability and hypertonicity, faster reflexes, and suppression of parasympathetic nervous system excessive use of the trapezius, sternomastoid and activity. Add to this the frequent occurrence of scalenes. Overworking these accessory breathing thoracic breathing at these times, associated with muscles can produce hypertonicity under normal

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conditions; if low CO 2 in addition is promoting hyperventilation routinely to 'push' the brain and weakness and hypersensitivity, it simply makes bring out abnormalities which may indicate things worse. One study produced long-term seizure potential. reductions in non-cardiac chest pain mainly by Research with military pilots during the training the patients to breathe more slowly and Second World War and later showed that more abdominally, thereby taking the strain off of hyperventilation impaired problem-solving and thoracic and neck muscles (DeGuire et al. 1992). other performance tasks relevant to flying. Motor Thoracic breathing, by the way, seems to be coordination and dexterity, balance, cognitive the avenue of conscious influence, used when we and perceptual tasks have all been shown to wish to override the automatic regulation, suffer with induced by whereas abdominal breathing is the default hyperventilation (Wyke 1963). Clinically, an system. Most writers on hyperventilation have individual in this condition will often complain of mentioned the prevalence of thoracic breathing, a 'spacey' feeling: impaired thinking, things or and Lure proposed that stress may be the the self not feeling real, poor definition of body provocative factor, while thoracic breathing boundaries, etc. In fact, explanations and constitutes the permissive factor (Lure 1976). It instructions about how to 'breathe better' may may be that voluntary use of the accessory not sink in very well at that moment because the breathing muscles begins as a response to cerebral impairment will interfere with learning. suffocation fear, an attempt to improve breathing Apart from cerebral vasoconstriction, the comfort, or a misguided preparation for exertion general tendency of hyperventilation to promote that never comes. This overcontrol can turn smooth-muscle constriction can affect the chronic, leading to dull, diffuse thoracic pain and gastrointestinal tract, peripheral and skin intercostal tenderness. circulation ('cool hands, cold feet'), coronary arteries and the bronchioles. These transient, Effects on the brain reversible effects can simulate more drastic ailments, and in some cases can magnify pre- Normal PaCO 2 concentration in the blood and in existing problems such as heart disease, exhaled air is around 5%; this is associated with Raynaud's disease and spastic colitis. optimal blood flow in the cerebrum. The corresponding figure expressed in mmHg is Chronic hyperventilation around 40. Below 30 is a commonly accepted point below which symptoms are more likely, Acute hyperventilation provides a foundation for and there is usually serious interference with understanding, but I want to bring attention to the cerebral blood supply. Positron emission other, more common type: subtle and chronic, tomography (PET) and magnetic resonance chemically more complex because the body is imaging (MRI) scans have shown that cerebral trying to adjust to it. This is an entity in itself and blood flow correlates area by area with mental differs from acute hyperventilation in several activity of the moment: for example, recalling a ways, not the least being the difficulty detecting it. face requires more blood flow in the right Recall the assertion that the body strives to hemisphere, while recalling a poem does the keep the pH where it should be. In the short run, same in the left hemisphere. Hyperventilation hyperventilation will raise the pH toward will certainly affect this delicate allotment of alkalosis, directly affecting circulation, muscle resources and disrupt stability of consciousness tension, smooth muscle, nerve conduction, in a global way as well. sensory functions, cerebral function, etc. But there With vasoconstriction (ischaemic hypoxia) are safeguards to prevent this from going on too attention and short-term memory are impaired; long. If hyperventilation persists for a few hours, vision mgy be diminished and light-headedness the body begins to compensate, primarily by may occur. The dominant electro-encephalogram changing the proportion of bicarbonate ions in (EEG) frequency actually drops, correlated with the blood. This is CO 2 in an alkaline, less efficient cortical processing. Hyperventilation transportable form, and changing its destabilizes the brain and can easily precipitate concentration permits fine tuning of blood pH. seizures in susceptible people. Neurologists use Since hyperventilation is causing alkalosis

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(higher pH than normal) the kidneys begin to Living on the edge correct the imbalance by excreting more Many individuals seem to live on the edge of bicarbonate, thus retaining acid. The pH will symptoms of . A CO2-deficient state return to normal, more or less, but the CO 2 can be maintained by an occasional sigh or deep remains low, leaving the individual in a breath, or by breathing only 10% above normal precarious state (Table 2). ventilation (Gardner 1996). In these chronic cases A parallel in principle to this bodily pH may be near normal because of the renal adjustment might be a postural defect which compensation, but the CO 2 remains low. Because reflects a psychological attitude of depression, of this, the chronic hyperventilator inhabits a anxiety, or defensiveness; while not optimal narrow zone of comfort with a lower threshold structurally, the stance amounts to a compromise for development of symptoms (Magarian 1982). between emotional input and body regulatory A slight increase in breathing without mechanisms. Obesity (or skinniness) is also accompanying muscle contraction may set off similar, in that the body is forced to accept and symptoms of hypocapnia. A slight increase in adapt to inadequate or excessive amounts of food acidity from breath-holding or sudden exercise consumed. We cannot assume that, because a can set off 'air hunger' because the kidneys have process seems deeply automatic, it is strictly dumped a proportion of the alkaline reserves physiological and immune to tampering from the (bicarbonate) in order to balance the excess higher aspects of an individual. Emotions and alkalinity (Fig. 3). So poor exercise tolerance can habitual behaviour can intrude anywhere. be yet another symptom of this syndrome.

Table 2 of chronic hyperventilation

Respiration: primarily thoracic, over 18 per minute, irregular (sighing, holding, labile), mouth-breathing, dyspnoea

Cold hands, indigestion

Chest pain, tightness

Poor sleep, nocturnal panic attacks

Over-sensitive to both exercise and relaxation

Easily exhausted with effort

Anxiety, restlessness, fidgeting

Muscle pain and sensitivity

Lowered serum bicarbonate and PaCO2, but blood pH normal

Chronic hyperventilation mechanisms

Long-term physiological adjustment (within hours) to respiratory alkalosis:

Bicarbonate buffer (alkaline) is excreted in order to reduce alkalosis and restore pH toward normal. Kidneys retain acid to compensate for loss of carbonic acid from the blood.

'False equilibrium': bicarbonate buffer depletion creates a fragile, somewhat stable biochemical state which depends on continued hyperventilation.

Symptoms are easily provoked by changes in breathing in either direction, because of a narrowed range between critical 'alarm' values for acidosis and alkalosis.

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Some researchers think that abrupt changes Breath-holding and drops in CO 2 level are more significant than (alkaline) the actual level itself: that is, erratic breathing, like an abrupt, jerky driver on the highway 7"51 ...... whom everyone avoids, may be harder on the pH 7.3 l body than slow, smooth changes (Lure 1987). The body may more easily adapt to steady hypocapnia than to an emotion-driven alternation between breath-holding and sighing. pC02 40 Anxiety 35 The relation between anxiety and B 30 hyperventilation is bi-directional, and moderated by individual differences. The proposition that hyperventilation is the ultimate cause of panic attacks is not as tenable now as it once seemed, = but the formulation goes as follows: C Hyperventilation lowers CO2, and the combination Arterial diameter of alkalosis and hypocapnia cause a flurry of symptoms which alarm the individual, stimulating more hyperventilation when an emergency situation Fig. 3 'Breath-holding:' as breath is retained, CO 2 is perceived. CO2 drops further; this worsens the rises. Being acidic, it promotes a drop in pH, which is symptoms, and so forth, in a classic vicious circle. associated with blood vessel vasodilatation to facilitate oxygen . (A) = pH; (B) = CO2; (C) = arterial This does seem true in some cases of panic, but diameter many others do not fit. An individual can report panicky feelings with normal CO 2, and CO 2 can be low with no panic at all. Some individuals can hyperventilate voluntarily to reach very low CO 2 sensitivity. Also, blood glucose seems to levels of PaCO 2 yet feel few symptoms, probably protect against the effects of lowered CO 2. The because their systems are better able to resist the symptomatic response to hyperventilation with effects or compensate. glucose at 70-75 mg% is much greater than when At least three factors seem to maximize this it is around 100 mg, even though the former is potential hyperventilation/anxiety connection. within the normal range for fasting blood sugar First, a tendency to interpret the sensations as (Engel Ferris & Logan 1947). dangerous (heart attack, brain tumour, fainting, It seems that even the clearly physiological etc.) will magnify symptoms and amplify the aspects of hypocapnia and alkalosis can be 'resonance' between mind and body in a negative mediated by mental factors. Some individuals way. This cognitive view has led to have a drastic drop in CO 2 during psychologically-based treatment of panic hyperventilation and have abundant symptoms, (Salkovskis & Clark 1990). Second is the but they do not worry about it and may even likelihood of breathing serving as a habitual bring the condition on for recreation. When expression of strong feelings, often conflict over hyperventilation is provoked during laboratory anger, frustration, death-fears, or recalled grief studies, panic patients often do not panic as (Conway 1994). Third is a physiological expected because the context is different. Former susceptib'~tlity to hyperventilation and its panic patients who have gone through a consequences. This may take the form of greater successful course of therapy lose their fear of the smooth-muscle contractility to a given amount of symptoms. Typically they are trained in hypocapnia (Gibbs 1992) or a central sensitivity to breathing regulation and also in reinterpreting CO 2. A "suffocation alarm" has been proposed by the symptoms as transient, understandable and Klein (1993) as an intervening variable affecting harmless, rather than catastrophic.

136 Accident ond Emergency Nursing (1999) 7, 130-140 1999 Harcourt Brace & Company Ltd Hyperventilation and the body

Normal breathing: alkalosis normal alkaline buffering Low COz Hyperventilation acidic ' " Symptoms of (overbreathing) T 7.3 9 9 50 air hunger Symptoms High-normal Breathing in this range? Go on an pH PetCO 2 Normal air diet

7.4 9 9 40 Low-normal Air hunger (underbreathing) Low CO2 acidosis Symptoms of 7.5 9 ~._...... 1...;3q...... cerebral vaso- Fig. 5 Chronic hyperventilation can be compared to alkaline constriction overeating; perhaps for fear of feeling breathless, people may overbreathe, gulping oxygen but depleting their systems of carbon dioxide and provoking symptoms associated with alkalosis Chronic hyperventilation reduced buffering acidic 9 When hypervenfilation does occur at times other than during muscular activity, it may be a 7.3 9 /145 necessary compensation for a condition that would worsen and be possibly life-threatening if ...... Symptoms of hyperventilation were not occurring. It could be --~ -airhunger responding to diabetic acidosis, for example, or pH PetCO 2 , which acidities the blood; 7.4 9 9 35 and emphysema can induce hyperventilation; also or Symptoms of , liver failure and anaemia. cerebral vaso- The possibility of seeing someone unaware of constriction their relevant medical condition is small, but still present; people vary in their readiness to consult 7.5 9 9 25 medical practitioners. Diagnosis of the so-called alkaline 'hypervenfilation syndrome' should be a medical decision; possible organic causes must be Fig. 4 When hyperventilation continues for several hours or more, there is a drive to restore normal pH by considered. See Gardner (1996) and Fried (1993) excreting more alkaline buffer. This compensation for further discussion. permits CO 2 at a level of 35 mmHg to co-exist with 7.4 Having said that, here are some tips: pH. Such an individual becomes subject to reduced capacity to tolerate acidosis from any source, including breath-holding, and is also closer to the 'symptom-line' Tests for reduced CO2. Note the two horizontal lines closer together in the right-hand diagram The clearest indication that an individual suffers from chronic hyperventilation is probably the Diagnosis combination of lowered CO 2 and near-normal blood pH, accompanied by habitual thoracic The chemical imbalance described here has a breathing. PaCO 2 and pH can be sampled from number of possible causes, some so clearly arterial blood, but this is invasive and represents organic that it is generally prudent to get medical a brief moment in time. If the patient happens to clearance before attempting to alter an hold his breath during the puncture, the value individual's breathing style in any detailed way. may be misleadingly normal.

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with symptoms of hyperventflation are more likely to show a delayed return to normal CO 2 level. The best-discriminating ratio settled on by the authors was 1:5 to 1:CO2 at baseline/CO 2 at Chest tightness 3 minutes after terminating hyperventilation. So Blurred vision if CO 2 originally at 40 does not recover to 27 after 3 minutes, that person would be predicted Heart palpitations to have trouble with overbreathing. King (1988) Tingling in fingers showed that hyperventilators are less aware Dizziness Loss of contact with surroundings than others of when their CO 2 is low. After a Anxiety hyperventilation test, they would signal that Difficulty taking a deep breath their breathing felt normal again when CO 2 was still in the subnormal range. This apparently altered set point may reflect habituation to a chronic imbalance or else 'loose End-tidal CO 2 can be measured easily from the standards" for some other reason. exhaled air via a small sampling tube leading to a 3. Peter Nixon's 'Think test' (Nixon & Freeman capnometer, which analyses each breath for CO 2 1987) involves exhorting the individual, while content. In the absence of lung disease, this being monitored by capnometry, to dwell on a correlates closely with arterial CO 2. disturbing emotional event or situation. If the Measurements can be obtained over long time breathing becomes disordered and the CO 2 intervals. However, capnometers are not standard clearly drops below baseline, this is equipment except in operating rooms or the office considered evidence of a general tendency to of a pulrnonologist. They are quite useful for hyperventilate during emotional states. This corrective breathing training and for feedback, loosely-defined test takes some skill to however, and some respiratory therapists and perform, but can be informative. Peter Nixon physiotherapists use them routinely. Though their is a London cardiologist who has cost when new can be US $3000-$5000, used units demonstrated the medical (especially cardio- are often available from hospitals or medical vascular) ramifications of chronic sources as new models are updated (Gilbert 1994). hyperventilation (Nixon 1989). Even if an individual reports symptoms 4. 'Effort syndrome': this is Nixon's delineation suggestive of hyperventilation, it does not mean of how hyperventilation-related deficiency in the condition is always present. Symptoms can alkaline buffering predisposes an individual come and go, and between times blood gas and to premature muscle fatigue, as shown by end-tidal CO 2 values may be normal. Many lowering of the anaerobic threshold (Nixon people occupy a category midway between 1994). This is tested with exercising on an 'acute' and 'chronic'. ergometer while CO 2 and work output are Several other tests have been found useful for measured. An abrupt downtum of CO 2 diagnosis: indicates this threshold and the onset of 1. The Nijmegen Test (van Doorn et al. 1982) hyperventilation associated with appearance consists of 16 prime symptoms most of metabolic acidosis. commonly reported by people who by other 5. The 'hyperventilation provocation test' is evidence tend to hyperventilate (for example, widely done by physicians and others as a 'Unable to breathe deeply' and 'Blurred, hazy quick test for reproducing some of the vision'. It is quickly administered, allows for symptoms. If the individual sees that the same ratings of frequency, and can serve as a good symptoms that have driven him from office to basis ~or further investigation (see Box 1). office can be produced in less than 3 minutes 2. Recovery after hyperventflating (Hardonk & of heavy breathing, he is likely to leam a Beumer 1979): while being monitored via valuable lesson. It is frequently reassuring to capnometry, the individual is asked to discover that the symptoms can be brought hyperventilate for 3 minutes to lower the CO 2, under voluntary control simply by and then resume normal breathing. Patients terminating the hyperventilation.

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There is controversy about the safety of perception, equilibrium, sensory functions and all provoking hyperventilation for test purposes. The smooth-muscle function, including circulation. If procedure does put strain on the heart and blood therapeutic bodywork is not proceeding well and vessels, causing transient vasoconstriction, some of the complaints mentioned are present, it ischaemia and often disturbance of the heart may help to look deeper into the possibility of rhythm. In the presence of heart disease or hyperventilation even though the breathing may cerebrovascular abnormalities, the risk increases to not be noticeably different. the point that it would be wise to have Also, it may be fruitful to investigate the electrocardiogram (ECG) monitoring and circumstances under which the symptoms worsen. resuscitation equipment nearby if the test is done As you might inquire about the context of at all. muscular or pain symptoms, ask as well about any Other suggestive signs and symptoms include: associated emotional issues, social or psychological events preceding or following a 1. prominent thoracic breathing flare-up, the habitual state of emotional tension, 2. frequent sighing or gasping etc. Sometimes even talking about these things 3. shortened breath-holding time will exacerbate symptoms through a barely 4. rapid or irregular breathing detectable increase in ventilation, which may still 5. mouth-breathing be adequate to drop CO 2 to a symptomatic level. 6. reporting of some of the hyperventilation indicators such as: a. light-headedness b. tingling or numb extremities References c. muscle weakness or twitching Conway A 1994 Breathing and feeling. In: Timrnons BH, d. disturbance of consciousness or of vision Ley R (ed). Behavioral and Psychological Approaches e. breathlessness to Breathing Disorders. Plenum, New York f. rapid heart rate DeGuire S, Gevirtz R, Kawahara Y, Maguire W 1992 Hyperventilation syndrome and the assessment of g. cool, pale skin, etc. treatment for functional cardiac symptoms. American None of these is truly specific to Journal of Cardiology 70:673--677 hyperventilation; they often accompany anxiety Engel GL, Ferris EB, Logan M 1947 Hyperventilation: analysis of clinical symptomatology. Annals of Internal states. Together, however, the combination of Medicine 27:683-704 visibly altered respiratory pattern with subjective Fried R 1993 The Psychology and Physiology of Breathing. reports as above should raise the question of Plenum, New York possible alkalosis. Gardner WN 1996 The pathophysiology of There is room for improvement in diagnosing hyperventilation disorders. Chest 109:516-534 Gibbs DM 1992 Hyperventilation-induced cerebral a condition that varies so much in its expression. ischemia in and effects of nimodipine. Yet some reading on the topic will give the reader American Journal of Psychiatry 149:1589-1591 a sense of how hyperventilation can sometimes Gilbert C 1994 Uses of a capnometer in clinical disrupt the body's biochemical regulation in a psychophysiology. Biofeedback (AAPB Newsletter) major way, leading to quite florid symptoms. The Winter, 22(4): 6-7 Hardonk HJ, Beumer HM 1979 Hyperventilation distinction between 'acute' and 'chronic' is syndrome. Handbook of Clinical Neurology 38:1 important; a with hyperventilation King J 1988 Hyperventilation: a therapist's point of view: stands out clearly, but when the overbreathing discussion paper. Journal of the Royal Society of becomes habitual for whatever reason, a murky, Medicine 81:532-536 incomplete adjustment develops which is more Klein DF 1993 False suffocation alarms, spontaneous and related conditions. Archives of General difficult to reverse, and calls for much more than Psychiatry 50:306-317 a paper bag or instructions to breathe more Ley R 1999 the modification of breathing behavior: slowly. Pavlovian and operant control in emotion and cognition. Behavior Modification (in press). Lum LC 1976 The syndrome of chronic habitual Conclusion hyperventilation. In: Hill OW (ed). Modem Trends in Psychosomatic Medicine. Butterworth, London To sum up, hyperventilation can affect many Lum LC 1981 Hyperventilation and anxiety state. Journal aspects of the muscular system, one's bodily of the Royal Society of Medicine 74:1-4

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Magarian GJ 1982 Hyperventilation syndromes: Salkovskis PM, Clark DM 1990 Affective responses to infrequently recognized common expressions of hyperventilation: a test of the cognitive model of panic. anxiety and stress. Medicine 61 (4): 219-236 Behaviour Research and Therapy 28(1): 51-61 Nixon PGF 1989 Hyperventilation and cardiac van Doom P, Colla P, Folgering H 1982 Control of end- symptoms. Internal Medicine for the Specialist 10 (12): tidal CO 2 in the hyperventilation syndrome: effects of 67-84 biofeedback and breathing instructions compared. Nixon PGF 1994 Effort syndrome: hyperventilation and Bulletin of European Physiopathology and Respiration reduction of anaerobic threshold. Biofeedback and Self- 18:829-836 Regulation 19(2): 155-169 Wyke B 1963 Brain Function and Metabolic Disorders: the Raichle ME, Plum F 1972 Hyperventilation and cerebral Neurological Effects of Hydrogen-ion Concentration. blood flow. 3:566-575 Butterworth, London

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