Air embolism

AIR EMBOLISM * WITH

SPECIAL

REFERENCE

TO ITS SURGICAL

HARRISON S. Chief Medical

MARTLAND,

IMPORTANCE

M.D.

Examiner of Essex County

NEWARK,

NEW

OST surgeons regard air and fat embolism as more or Iess nehuIous entities, which are rareIy serious enough to cause concern. Both these conditions occur, however, more frequently than is suspected, and fatahties are occasionaIIy encountered. These deaths are usualIy sudden but may at times be somewhat protracted. The author, therefore, believes that the type of case in whichfatal air embolism may occur should be emphasized, and the climca1 symptoms and pathoIogica1 findings reviewed. Air emboIism is the result of the entrance of air into the venous circulation (or occasionally the systemic circuIation), with consequent blockage of the right side of the heart and the puImonary circulation, or the cerebra1 or coronary circulations. Blockade of vesseIs in other Iocations are of no practical significance, since no disastrous results ensue. For air embolism to produce death, air must enter the circulation in large quantities in a short period of time. Even large quantities of air may enter the circulation over a long period of time without fatal resuIts. For instance, a liter of oxygen has been injected into man in the course of an hour without serious injury. Of course oxygen is more readiIy absorbed than air which contains only 21 per cent oxygen. SmalI quantities of air rareIy produce

M

JERSEY

death unIess the air is trapped in the coronary arteries or in some vital cerebra1 location. There are two main varieties of air embolism: Pulmonary embolism which is much more frequent and important, and systemic embolism. FATAL.

PULMONARY

AIR

EMBOLISM

When a Iarge volume of air reaches the right side of the heat in a short period of time, foamy blood containing large bubbIes of air is formed. This is more compressible than norma bIood and less readiIy expehed, a considerable amount of air remaining after each systole. Thus, the pulmonary circuIation becomes obstructed, the right auricle and ventricle are distended and tympanitic, the peripheral venous pressure is increased and sudden death occurs due to interference with proper ventricuIar contraction. (Fig. I .) Symptoms. Shortly after the onset, the patient becomes dyspnoeic, cyanotic and pulseless. Death usuahy occurs in a few minutes. The clinica mode of death is similar to that observed in massive pulmonary embolism, such as occurs after thrombosis of the veins of the lower extremity. There is an “acute car pulmonale.” Autopsy Findings. Air emboIism of this type can often be suspected from the history of the case and the conditions under which death has occurred. No death from

* From the Off& of the Chief MedicaI Examiner of Essex County, Newark, N. J.; the Department of Pathology of the Newark City Hospital; and the Department of Forensic hledicine, New York University College of Medicine. 281

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air embolism, however, is proved unless proper autopsy technic is used for its demonstration. Two methods are in use: (I) After opening the chest and abdominaI cavities, all great vessels are ligated, in&ding the inferior vena cava and the lungs and heart removed en masse. They are then immersed in a basin of water and the right ventricIe incised. Air bubbles escape if air embolism is present. In routine medicolega1 autopsies, I have opposed any autopsy technic in which organs are removed en masse. The organs are puhed and dragged out, artefacts are common, and important evidence is often missed or destroyed.* (2) For the above reasons I prefer the origina Virchow autopsy technic, in which nothing is disturbed unti1 it has thoroughIy been investigated, and the organs are removed in a Iogical and methodical manner Thus, in the demonstration of air emboIism, the abdomen and chest are carefuIIy exposed. The sternocIavicuIar joints and the cartiIages of the first two ribs are not disturbed for fear of cutting the vessels of the upper chest and the Iower two-thirds of the sternum removed without undue force. The pericardium is opened and the heart exposed. In the pulmonary type of air embolism, the right side of the heart will be found distended, often bahooned out and tympanitic The inferior and superior on percussion. vena cavae wil1 be distended with what appears to be frothy bIood. Then, the pericardium, chest and abdomina1 cavities are filled with water. The heart often shows a tendency to rise to the surface. It is heId back beIow the surface of the water and the right ventricle is then incised. In puImonary air embohsm large bubbles of’ air and frothy, foamy blood escapes. The inferior vena cava may then be punctured under water. * The “en masse” autopsy technic, often calIed the Le Count method, is very popular in this country. In general, I believe its use, as a routine procedure, is very apt to lead to careless and incomplete autopsies. It has some specia1 advantages, however, which are limited.

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It is important that the autopsy be performed as soon as possible after death, so that air emboIism is not confused with the gases of decomposition. There shouId be no visibIe signs of such decomposition, i.e., no hemoIysis in the bIood or reddish staining of the endocardium or intima of the veins. FATAL

SYSTEMATIC

AIR

EMBOLISM

In a few cases, air may enter the Ieft side of the heart in the form of foamy, frothy bIood containing smaI1 air bubbles. Systemic air emboIism results. As a ruIe the air is rapidIy absorbed producing IittIe or no symptoms unIess it reaches the brain in considerabIe amounts or is caught in the coronary circuIation. The effect of air in other organs is negIigibIe. In most of these cases the air has originaIIy entered the venous circulation resuiting in puImonary air emboIism. Death, however, has not occurred and smal1 amounts of air in the form of fine bubbIes have passed through the Iungs or through a patent foramen ovaIe into the left side of the heart. Though a patent foramen is found in 25 per cent of individuaIs, the opening is usuaIIy smal1 and physioIogicaIIy closed by the hrgher pressure in the left auricle. However, in shock, when the pressure in the right side of the heart may approach that in the Ieft side, paradoxical embohsm may occur. Air may aIso enter directIy into the left side of the heart from injury to a pulmonary vein without entering the venous circulation. This may occur during artificia1 pneumothorax. In addition, air may enter the vertebral system of veins and pass directIy to the brain, by-passing the heart. Such embolism may occur in air insufllation around the adrenaIs for their roentgenographic visuaIization. Cerebral Air Embolism. UsuaIIy if considerable air reaches the Ieft side of the heart, the brain is Iikely to receive most of it. Cerebra1 air emboIism is charac-

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terized by usually a slow mode of death. The patient lives a few days as a rule in a maniacal, stuporous or comatose condition. The characteristic autopsy findings in

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in fat embolism, and from concussion hemorrhages in blunt force injuries to the brain and the various forms of hemorrhagic encephalitis.

FIG. I. FataI air embolism of the pulmonary type. (I) Entrance of air into uterine veins; (2) air in inferior vena cava; (3) right side of heart distended with foamy blood and Large air bubbles preventing proper systoles; and (4) foamy blood containing smaller air bubbtes entering pulmonary circulation. Case of sudden death following intravaginal powder insufflation for treatment of pruritus.

cases are multiple petecbial bemorthroughout the white matter of the brain. These must be differentiated from similar appearing hemorrhages encountered

such

rbages

Air bubbles in the veins of the leptomeninges are usuaIly an artefact occurring in the routine removal of the brain and are of no significance.

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Coronary Air Embolism. Should the coronary circulation be bIocked by air, sudden death results. This is difficult to

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systemic air embohsm has been observed under a variety of conditions. They may be briefly discussed as follows:

FIG. .z. Fatal

air emboIism of the systemic type. Note air entering the Ieft side of the heart (I) from lungs, (2) through patent foramen, and (3) through pulmonary vein injured during artificial pneumothorax; (4) cerebra1 air embolism with multiple hemorrhages in white matter; (5) coronary air embolism.

prove at autopsy, since air bubbles are frequentIy sucked in during routine removaI of the heart. The anatomical pathof the systemic ways in air embolism variety is shown in Figure 2. VARIOUS

CONDITIONS

IN

EMBOLISM

MAY

W-HICH

FATAL

AIR

OCCUR

Fatal air embolism is almost aIways of the pulmonary type. In the experience of the medical examiner, both puImonary and

Head. Wounds or operations in which the dura1 sinuses are injured may cause air embohsm. The waIIs of these sinuses are stiff, therefore, do not collapse and favor the entrance of air. Lavage

of the Nasal

the antra

Highmori,

immediate

death.

three

sudden

deaths

Sinuses,

easily

especiaIIy

has been followed The

author

in clinics

cian’s offrces from this procedure.

knows

by of

and physi-

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Air under considerabIe pressure (often five to ten pounds) is bIown through the antrum to repIace the irrigating fluid. Great care shouId be taken to control this pressure. Often in offIce buildings, compressed air is piped to individual offIces, and is not regulated by pressure gauges or reducing valves. Pressures may vary and reach dangerous amounts. Neck and Upper Chest. Wounds and operations in the region of the carotid vessels may cause air embolism. This is particularly true when the jugular vein is injured, during thyroid operations, in the remova of tumors of the neck, in the repair of arteriovenous aneurysms, et cetera. The surgeon may notice a hissing sound or “souflement” as air is sucked in. Death may quickI? follow as the right side of the heart is raprdly f3Ied with air. Any type of wound or operation in the neck or upper chest which cuts or penetrates large veins of the neck or mediastinum may be complicated by air emboIism. Sometimes the air may enter the left side of the heart from injury to a pulmonary vein. Peripheral Veins. Seldom is any large amount of air injected in the periphera1 veins. Small amounts frequently enter in various intravenous injections but rarely produce symptoms. Fats1 air embolism, however, has been observed after continuous intravenous injections, especially when tubing has sIipped and becomes disconnected and air is sucked in for severa minutes. In blood donations, using cIosed types of apparatus, air has been forced into veins of by unwittingIy condonor or recipient, necting the positive pressure tube to the individual, with resultant serious reaction. Air emboIism has Urinary Bladder. occurred after injections of air into the urinary bIadder for the purpose of taking aerograms or for operative or therapeutic purposes. Ulceration of the bIadder favors the entrance of air. Uterus. Fatal air embolism is, however, most frequent after injection of air into the uterine cavity.

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CriminaI Abortions are the most frequent cause of fata air embolism. It usually occurs in dirty abortions, often performed by midwives using the old Hungarian syringe method of injecting soap-suds and air directly into the uterine cavity. Such fatalities are sometimes accompanied by fat or oi1 embolism. The pIacenta is often torn and partially separated aIlowing large quantities of air to rush into materna1 sinuses and uterine veins. Obstetrical Cases have been complicated by air emboIism, especialIy at the delivery of cases of pIacenta previa. Diagnostic and Therapeutic jections have been followed

Uterine

In-

by air embolism, with occasiona fatal results. In testing of the FalIopian tubes the patency (Rubin test), physicians have occasionaIIy observed sudden collapse and even confrom which, fortunatery, the vuIsions, patients have recovered. Fatal air emboIism has occurred. The air injections should be carefully controIIed and pressures not exceeding 150 mm. of Hg. should be used. Some physicians have been using dangerous pressures of 200 mm. or more. Intravaginal Insuflations for the treatment of trichomonas infections and pruritus have caused sudden death from pulmonary air emboIism. * In these procedures the vagina is intentionaIIy distended with air so that its foIds wiI1 be smoothed out, aIlowing medicina1 powder to cover its waIIs. for Pneumoperitoneum Transuterine pneumoroentgenographic diagiosis couId easily be complicated by air emboIism, especiaIIy if attempted near a menstrual period, or after uterine curettage. Peritoneum. Direct raphy is usuaIIy not

Pneumoroentgenog-

considered dangerous procedure. However, ture of a large intra-abdomina1 resuIt in air embolism. If the system of veins were injured,

to be a the puncvein could vertebra1 air might

* MARTLAND, HARRISON S. FataI air embolism due to powder insufHators used in gynecological treatments. Am. J. Surg., 68: 164, 1945.

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by-pass the heart and go directIy to the brain, resuIting in systemic air emboIism of the cerebral type. Pleura. Artijcial Pneumotboraces are often comphcated by air embohsm but death rareIy results, and recovery is foIlowered by no sequeIIae. In some one in every go0 or 1,000 artificia1 pneumothoraces the patient may suddenly fee1 queer, often go into temporary shock and even have a convulsion. In the rare fatal case, air embolism has been reported, the air gaining access to the systemic circuIation through an injured pulmonary vein. Some authorities, however, do not beIieve that these reactions are due to air emboIism and attribute them to some unexpIained pleural-cardio-inhibitory reff ex. As these deaths are said to be sudden, and as sudden death from cerebral or coronary air emboIism is difficuIt to prove at autopsy, I am of the opinion that the cause of death in these cases is stiI1 controversial. Retroperitoneum. Air insufIIations in the region of adrena gIands for the roentgenographic visualization of adrenal tumors, etc., have been folIowed by death said to have been due to air emboIism. It is possibIe in this procedure to injure vertebral veins and have direct cerebra1 air embolism. CONCLUSIONS

The various conditions in which air occur have been discussed. Most of these are mainIy of surgica1 interest. The introduction of air under pressure into the uterine cavity is the commonest cause of air emboIism. 2. Air embolism is not often a serious I.

embolism may

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compIication, and gives rise to little or no symptomatology whatsoever. Reactions which are sometimes alarming, such as collapse, shock and even ConvuIsions, may occur but these are often recoverable Ieaving no sequellae. 3. Fatalities occasionahy are encountered. The common type of Jatal air embolism is the pulmonary type. In this form large quantities of air reach the right side of the heart in a short period of time and interfere with proper ventricular systoles and resuIts in sudden asphyxial death. 4. A Iess common form of fatal air embolism is the systematic variety in which cerebral air embolzsm is the most important. Deaths in these instances are protracted, sometimes taking two to five days, during which the patient is maniacal, stuporous or comatose. The characteristic pathologica1 lesions are multipIe, petechia1 hemorrhages in the white matter of the brain. In rare instances coronary air embolism causes sudden death. This is diffrcuIt to prove at autopsy and many cases in literature wouId not bear critical analysis. 5. Greater care shouId be used in the various diagnostic and therapeutic procedures which depend upon the introduction of air under pressure into the vagina, uterus, urinary bIadder, peritoneum and perinephric space in order to prevent such catastrophies. Precautions should be taken in operations around the large veins of the neck, upper chest, mediastinum and dura1 sinuses to prevent air embolism as a compIication. And the possibiIity of air emboIism in gunshot wounds, stab wounds and cuts in these locations should be borne in mind.