Air contamination during medical treatment results in deposits of microemboli in the lungs: An autopsy study

Abstract

Introduction: Microbubbles of air may enter into patients during conventional hemodialysis, infusions of fluids, or by injections. The aim of this study was to investigate whether the air that enters the patient during hemodialysis can be detected in the lungs after death, and if so, whether this may be related to tissue damage. Methods: The material consisted of lung tissue from five chronic hemodialysis patients who died either during (two) or after hemodialysis (range 10 min from start until 3333 min after the last hemodialysis session); as reference group tissue was taken from seven patients who died due to amyotrophic lateral sclerosis. The lung tissue was investigated by microscopy after autopsy using a fluorescein-marked polyclonal antibody against fibrinogen as a marker for clots preformed before death. Results: All five hemodialysis patients had microbubbles of air in the lung tissue, whereas two of seven amyotrophic lateral sclerosis patients had such findings (Fisher’s test p = 0.0278, relative risk = 3.5, confidence interval: 1.08–11.3). There were more microbubbles of air/10 randomly investigated microscopic fields of tissue in the hemodialysis patients than the amyotrophic lateral sclerosis patients (Student’s test, p < 0.05). All hemodialysis patients had a medium graded extent of pulmonary fibrosis that was not found in any of the ALS patients. The microbubbles of air were surrounded by fibrin as a sign of development of clots around the air bubbles while the patients were still alive. Conclusion: Exposure to microbubbles of air during various treatments such as hemodialysis may result in microemboli. Future studies should clarify whether microbubbles of air contribute to tissue scarring. We suggest preventive measures against the exposure to microbubbles of air during especially repeated exposures such as hemodialysis.

Interdialytic weight gain of less than 2.5% seems to limit cardiac damage during hemodialysis

“… 37 An additional impact on myocardial function was that of the altered saturation, we reported, which causes perpetual stiffness. Finally, the role of MES, constituting of air bubbles covered by fibrin, that we detected in our patients (at autopsy), 27 , 28 could consequently worsen the subendocardial dysfunction and ischemia and hence a rise in the baseline markers’ levels. The microemboli passing from the dialysis device in to the vessels will mainly end up in the lungs, where they may contribute to a progressive fibrosis and pulmonary hypertension and subsequent cardiac strain.…”

“…The microemboli passing from the dialysis device in to the vessels will mainly end up in the lungs, where they may contribute to a progressive fibrosis and pulmonary hypertension and subsequent cardiac strain. 27 , 28 This would be strengthened by a majority of HD patients who suffer from pulmonary hypertension. 38 , 39 Besides fluid overload the pulmonary hypertension will contribute to increased right heart work load what subsequently increases risk of mortality.…”

“…Microembolic signals (MES) were measured at the return bloodline, after the venous air trap, using ultrasound (CMD-10, Hatteland, Royken, Norway). Autopsy studies, 27,28 showed that such signals at this point are caused by air emboli covered by fibrin or solely clots present in the blood returning to the patient. Cumulative data were achieved at 30 and 180 min.…”

“…The design allowed each patient to be investigated during a mid-week HD session, in a randomized order. Previous studies showed that air exposure is different during various modes of HD 23 , 24 , 29 , 30 and may deposit in the body 27 , 28 and interfere with biocompatibility. 26 Since frequently used synthetic dialyzers are made of polysulfone, we decided to use one commonly used product in Europe: the steam sterilized dry stored and compare with a gamma sterilized wet stored dialyzers that is more common in Japan.…”

“…Numerous air bubbles are not fully absorbed but covered by fibrin and deposit as microemboli in the body. The first location to be trapped are the lungs 27 but passage into the arterial circuit have verified such emboli also in the brain and heart. 28 There is, to our knowledge, no comparative study that clarifies if modern polysulfone dialyzers cause different biochemical responses in different dialysis settings using either “high” versus “low” blood levels in the air trap and steam sterilized dry dialyzers or wet stored gamma irradiated dialyzers.…”