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Pulmonary fat and bone marrow embolism in aircraft accident victims
Pathology (1983), 15, pp. 131-5
PULMONARY FAT AND BONE MARROW EMBOLISM IN AIRCRAFT ACCIDENT VICTIMS ANTHONY R. BIERREAND T. D. KOELMEYER Department of Pathology, University oj Auckland School of Medicine, Auckland, New Zealand
Summary On 28 November 1979, an Air New Zealand DClO aircraft crashed into Mt Erebus, Antarctica with the loss of 257 passengers and crew. Postmortem examinations were carried out on 231 victims in Auckland, 4641 kilometres north of the crash site, and lung tissue was present in 205 cases. Pulmonary fat emboli were present in 134 cases (65%), pulmonary bone marrow emboli in 60 (29%) and pulmonary edema in 76 cases (37%). Clear relationships were demonstrated, firstly between the extent of fat and bone marrow embolism, secondly between the extent of fat and bone marrow embolism and the presence of pulmonary edema, and thirdly between the extent of fat and bone marrow embolism and the extent of cardiovascular damage. It was apparent that death had occurred immediately following impact, and the extent of fat and bone marrow embolism varied inversely with the severity of the injuries found. The most severely injured victims were those seated in the rear cabin of the aircraft suggesting that this was the site of impact with the ground. Our studies show that pulmonary fat embolism occurs very rapidly after severe injury and is followed by increasing numbers of fat and bone marrow emboli depending on the nature of the mortal injuries. Key words: embolism, fat, bone marrow, pulmonary, aircraft accidents. fractures, forensic medicine
INTRODUCTION The presence of fat and bone marrow emboli in lung tissue following trauma t o bones has been well documented.'-5 Fat and bone marrow emboli are thought to originate at the site of trauma and especially from the injured marrow of fractured bones.6 Globules of fat released from ruptured fat cells gain access to the circulation through torn venules as a result of a local shift in the differential between extravascular and intravascular pressures. It has been demonstrated that extravascular pressure greater than intravascular pressure within the marrow of fractured bones permits entry of fat globules and fragments of bone marrow into the c i r c ~ l a t i o n . ~
Pulmonary fat embolism occurs very rapidly after injury6.*. and when death follows shortly after injury, pulmonary fat and bone marrow emboli serve as markers for antemortem injury to bone." Mason" reported finding pulmonary fat embolism in 247; and pulmonary bone marrow embolism in 2 1 x of 3 1 1 victims of a number of separate aircraft accidents who were thought to have died immediately. The aims of this investigation were firstly, to establish the incidence of fat and bone marrow embolism in the lungs of a large group of severely injured individuals all of whom had been killed instantly, and secondly, to assess the role that study of pulmonary fat and bone marrow embolism may play in the reconstruction of an aircraft accident involving a large number of fatalities.
MATERIALS AND METHODS On 28 November 1979 an Air New Zealand DClO aircraft on a scenic flight crashed into the slopes of Mt Erebus. an active volcano on Ross Island, Antarctica. There were no survivors amongst the 257 passengers and crew on board. Disintegration ofthe aircraft was virtually complete with only the tail section and a small portion of fuselage readily recognizable. Wreckage and bodies were spread over an area measuring 570 metres by 120 metres indicating a severe force of impact. Two-hundred-and-thirty-one bodies were recovered, and postmortem examinations were carried out in Auckland, 4641 kilometres north of the crash site, on all of these as part of the identification procedure." All showed severe injuries ranging from almost total disintegration of the body to those which showed significant internal damage, such as fracture dislocation of the cervical vertebrae, with relatively few external signs of injury. All suffered bony fractures. Coroner's inquests into these deaths established that death followed immediately after impact in all cases.I2 Postmortem examinations were not carried out on 26 of the victims either because no body was recovered or the extent of injury was so severe that an adequate examination was not possible. Lung tissue was present in 205 of the 231 victims subjected t o postmortem examination. Twelve random blocks of lung tissue each measuring approximately 2 x 1 cm were obtained from each of the 205 victims, and were fixed by immersion in loo,, neutral formal saline. Six blocks were dehydrated in alcohol, cleared in xylol, and impregnated and embedded in paraffin wax. Sections 5p thick were cut from each of the remaining 6 blocks and stained either with oil red 0 or Sudan 111 and IV. Only fat globules which wereclearlyintravascular and deformed into elongated or sausage shaped ovals were identified as fat emboli. Free fat globules within lung tissue were excluded.
132
Pathology (1983). 15, April
BIERRE & KOELMEYER
A system (Table 1) was devised to assess objectively the extent of pulmonary fat embolism. The extent of pulmonary bone marrow embolism was assessed using the index of Masonlo (Table 2).
TABLE1 Grade 0 Grade 1 Grade 2 Grade 3 LPF
=
Q
The system of classification of the extent of pulmonary fat embolism (LPF = low power field) No emboli found Less than 6 emboli/lO LPF 6 to 35 emboli/lO L P F Greater than 35 emboli/lOLPF
43.75~
Type A Classification of slide Equivocal and acceptable Positive 1-2 emboli Positive 3-5 emboli Positive 6 + emboli
Score 1 point 2 points 4 points 6 points
Notes: n = number of slides examined A score of 1 4 = mildly positive. 5 and above = markedly positive.
The extent of pulmonary alveolar edema was also recorded. Alveolar edema was defined as the presence of pink finely granular proteinaceous material which was seen in more than 10 alveoli in 2 microscopic low of each of the 6 blocks of lung tissue power fields (LPF = 43.75~) ardined with hematoxylin and eosin. The presence or absence of lacerations of the heart or aorta was recorded and compared with the extent of pulmonary fat and bone marrow embolism in each case. The injuries seen in the victims were divided into 3 groups on the basis that the extent of injuries reflected the severity of the force applied. The three groups are illustrated in Fig. 1, as Type A, Type B, and Type C. The extent of pulmonary fat and bone marrow embolism in those people who were positively identified wascompared with the position of the seat assigned to each person o n the aircraft.
Combinations of fractures of Spine Pelvis Thigh Leg Ankle Skull Ribs .f Sofl Tissue Injury
Type A plus 1-2 limbs amputated f decapitation
Type c Type A & B plus further injuries
FIG. 1 Classification of the severity of injury
TABLE3 The incidence of pulmonary fat embolism Fat embolism no.
(7;)
Total
Grade 1
Grade 2
Grade 3
134 (65)
52 (25)
51 (25)
31 (15)
TABLE4
The incidence of pulmonary bone marrow embolism Bone marrow embolism no.
(06)
Total
Mildly positive
Markedly positive
60 (29)
32 (16)
28 (14)
RESULTS The incidence of pulmonary fat and bone marrow embolism in the 205 cases studied is shown in Tables 3 and 4. Figure 2 shows the relationship between pulmonary fat and bone marrow embolism. Bone marrow emboli were not found without fat emboli. As the extent of fat embolism increased, so did the extent of bone marrow embolism. All those cases with bone marrow embolism and grade 1 fat embolism had mildly positive bone marrow embolism, whereas among those with bone marrow embolism and grade 3 fat embolism only 38% (9) had mildly positive bone marrow embolism, and 637; (1 5) had markedly positive bone marrow embolism. Pulmonary edema was present in 76 cases (37%). Of those without fat emboli, 11% had pulmonary edema, whereas pulmonary edema was present in 37% of those with grade 1 fat embolism, 49% with grade 3 fat
Type
embolism, and 73% of those with bone marrow embolism. In Table 5 the extent of damage to the cardiovascular system is correlated with the presence or absence of pulmonary fat and bone marrow emboli. Those cases with intact cardiovascular systems had 4 times the incidence of bone marrow embolism and 1.75 times the incidence of fat embolism compared with those with lacerations of the heart and aorta. Forty-nine per cent of cases with lacerations of the heart or aorta had some fat emboli present but of these 50% had grade 1 fat embolism and only 11% had grade 3 fat embolism. One case in
133 with grade 2 or 3 fat embolism or bone marrow embolism. Of those cases with no lung tissue present 70", had type C pattern of injury. The extent of pulmonary fat and bone marrow embolism in each case and the seating position of that person are shown in Fig. 3. Of the 205 cases studied, 18 were crew members, and their positions at the time of impact could not be ascertained. Seven cases were not identified and so could not be assigned a seat number. N o fat or bone marrow emboli were seen in any of these 7 cases. It was possible to assign seat numbers to the remaining 180 of those studied. In the front cabin of the aircraft results were obtained for 28 of the 30 seats. Fat embolism grade 2, or grade 3 or bone marrow embolism was present in 61",, (17), fat embolism grade 1 in 25";, ( 7 ) ,and in 14'" (4) no fat emboli were present. In the middle cabin results were obtained for 66 of the 79 seats. Fat embolism grade 2 or grade 3 or FAT A N D BONE M A R R O W EMBOLISM
Bone Marrow Embolism
a
Markedly positive Mildly positive Total
Number Cases
1 ,m, .:.:.>:
5
........ .:.:.:.: ........ .... ........ .... .... .......*
~
Fat Embolism Grade
FIG. 2 Comparison of the extent of pulmonary fat embolism and the extent of pulmonary bone marrow embolism TABLE5
Comparison of the presence of pulmonary fat and bone marrow embolism and the presence of damage to the cardiovascular system
Heart or aorta
!
Total no. ('/")
I
Intact Lacerated
~
1
90(44) 115 (56)
Embolism absent no. ("/d 13 (14)
59 (51)
no. ("J
1
77 (86) 56 (49)
which the heart was absent at postmortem examination had grade 2 fat embolism and markedly positive bone marrow embolism. In Table 6 the extent of pulmonary fat embolism and the presence of pulmonary bone marrow embolism are compared with the severity of injury. The distribution of injuries seen in the 26 cases in which no lung tissue was present at postmortem examination is also recorded. These data show that, among cases without fat emboli or with only grade 1 fat embolism, a greater proportion had type B and type C patterns of injury than among cases TABLE6
Comparison of the severity of injury with the extent of pulmonary fat embolism, and the presence of pulmonary bone marrow embolism in 205 cases. The severity of injury seen in those cases with no lung tissue present has been included
Embolism extent Type A Fat embolism Grade 0 Grade 1 Grade 2 Grade 3
Severity of Injury Type B. Type C
'Iu
Bone marrow embolism ":,
No lung tissue present 5" (26 cases)
Bone Marrow embolism no. ("J
embolism
63 75 94 94
21 23 6 6
16
98
2
0
2 0 0
1
45 (50) 14 (12)
bone marrow embolism was present in 62",, (41), fat embolism grade 1 in 14", (9), and no fat emboli were present in 24",, (16). In the rear cabin, results were obtained for 86 of the 128 seats. Fat embolism grade 2 or grade 3 or bone marrow embolism was present in 26", (22), fat embolism grade 1 in 30"" (26), and no fat emboli were present in 44% (38). Of the 26 cases in which no lung tissue was found 7 were identified. Six were passengers, and all were seated in the rear cabin of the aircraft (Fig. 3). Four of these passengershad type C pattern of injury and 2 had type A pattern of injury
DISCUSSION This investigation has shown that fat and bone marrow emboli are found in the lungs of severely injured individuals thought to have been killed instantly. It has also demonstrated a clear relationship. firstly between the extent of fat embolism and the extent of bone marrow embolism; secondly, between the extent of fat and bone marrow embolism and the presence of pulmonary edema; and thirdly between the extent of fat and bone marrow embolism and the presence or absence of cardiovascular damage. The finding of pulmonary fat and bone marrow embolism in the victims of this aircraft crash supports the
134
Pathology (1983), 15, April
BIERRE & KOELMEYER
~ t ~ ~ ~ Grade ' l 2-3 s m Fat Embolism Grade 1
No Lung Tissue Present
nunidentified
NO Fot Embolism
FIG. 3 Comparison of the extent of pulmonary fat embolism and the presence of pulmonary bone marrow embolism with the seating plan of the aircraft
assertion that fat and bone marrow embolism occurs very rapidly, certainly within a few seconds of injury. The relationship found between pulmonary fat embolism and bone marrow embolism in severely injured individuals thought to have been killed instantly indicates that, if bone marrow embolism is present, one should also be able to demonstrate fat emboli, and that the more extensive the fat embolism the more likely that bone marrow embolism will be present. The finding that the incidence of pulmonary edema increases with the extent of pulmonary fat embolism and is high in the presence of pulmonary bone marrow embolism supports the concept that the production of emboli is time dependent. Pulmonary emboli and edema are seen only if cardiovascular circulation is present following bony injury, and both increase in extent if the circulation persists. The anomalous cases that had pulmonary fat embolism with lacerations to the heart or aorta may be explained on the basis of multiple episodes of injury which were known to have occurred in this aircraft crash. l 3 A clear relationship has also been demonstrated between the extent of pulmonary fat embolism and the presence of bone marrow embolism, and the severity of injury. Those with fat embolism grade 2 or 3 or with bone marrow embolism were found to be less severely injured than those with fat embolism grade 1 or no fat embolism. Thus where a large number of individuals were subjected to the same force, it is possible to use the extent of pulmonary fat and bone marrow embolism as an objective indicator of the severity of injury. Comparison of the extent of pulmonary fat embolism and the presence of bone marrow embolism with the seating plan of the aircraft indicates that more of the severely injured passengers occupied the seats in the rear cabin of the aircraft than in the front and middle cabins. This conclusion is supported by the presence in the rear cabin of those positively identified passengers in whom no lung tissue was present, the majority of whom had type C pattern of injury. It was evident from the postmortem examinations that a meal had been served shortly before the crash occurred, providing circumstantial evidence
that the passengers would have been seated in or close to their allotted seats. If the greatest force were applied to the aircraft at the point and time of initial impact, these findings suggest that the rear section of the aircraft hit the ground first. The same conclusion was reached by aircraft accident investigators following inspection of the crash site and analysis of the digital flight data r e ~ 0 r d e r . lIf~ the rear section of the aircraft was the point of impact on the mountain slope, this indicates that the aircraft was attempting to gain altitude at the moment of impact. This study has shown that the production of fat embolism is closely related to that of bone marrow embolism, and that both are time dependent and correlated with a number of variables such as an intact cardiovascular system. It would appear that following severe body injury, in those individuals thought to have been killed instantly, fat embolism to the lungs occurs very rapidly and, if time permits, is followed by increasing numbers of fat emboli and bone marrow emboli, all within a few seconds of injury. In this aircraft accident the victims died as a result of the impact and not from subsequent burns. The rear section ofthe aircraft was the site ofinitial impact with the ground. In these circumstances study of the presence and extent of pulmonary fat and bone marrow embolism in the victims may provide much information regarding the details of an aircraft accident and may be of particular importance when the flight data recorder is unavailable to investigators.
ACKNOWLEDGEMENTS The authors wish to thank Associrite Professor F. J. Cairns, Professor P. B. Herdson and Drs G . C. Hitchcock, W. M. I. Smeeton and B. J. L. Synek of the Department of Pathology, University of Auckland, School of Medicine for the use of postmortem material. We also wish to thank Mr R. Chippindale, Chief Inspector of Air Accidents, Ministry of Transport, Wellington, for permission to refer to Aircraft Accident Report No. 79-139. We are indebted to Associate Professor F. J. Cairns, Professor J. B. Gavin
FAT AND BONE MARROW EMBOLISM
and Professor P. B. Herdson for their advice and criticism of the manuscript. Address for correspondence: A.R.B., Department of Pathology, University of Auckland, School of Medicine, Private Bag, Auckland. New Zealand
References I . ARMINJ, GRANT RT. Observations on gross pulmonary embolism in man and rabbits. Clin Sci 1951; 10:441-89. 2. SCULLYRE. Fat embolism in Korean battle casualties. Am J Pathol 1956; 32:319-97. 3. EMSONHE. Fat embolism studies in 100 patients dying after injury. J Clin Pathol 1958; I1:28-35. 4. SEVITTS. Fat embolism in patients with fractured hips. Br Med J 1972; 2:257-62. 5. BLOCK B. Fatal fat embolism following severe donkey bites. J Forensic Sci SOC1977; 16:231-3.
135
6. WATSONAJ. Genesis of fat emboli. J Clin Pathol23 (Suppl) (R Coil Pathol) 1970; 4: 13242. HD. Dynamics of parenchymatous embolism 7. YOUNGJS. GRIFFITH in relationship to the dissemination of malignant tumours. J Pathol Bacteriol 1950: 62:293-311. 8. KALLOST, ENISJE, GOLLAN F. DAVISJH. Intramedullary pressure and pulmonary embolism of femoral medullary contents in dogs during insertion of bone cement and a prosthesis. J Bone Joint Surg Am 1974; 56A:1363-7. V, MCCARROLL J R . Fat embolism in trauma. Arch Pathol 9. PALMOVIC 1965; 80:630-5. 10. MASONJK. Pulmonary fat and bone marrow embolism as an indication of antemortem violence. Med Sci Law 1968; 8:200-6. 11. CAIRNSFJ, HERDSON PB. HITCHCOCK G C et al. Aircrash on Mount Erebus. Med Sci Law 1981; 21:18&8. 12. AUCKLAND CORONER’S COURTINQUEST REPORT.22-30 January 1980. 13. AIRCRAFT ACCIDENT REPORTNo. 79-139. Office of Air Accident Investigations. Ministry of Transport, Wellington, pp. 20-1.
PULMONARY FAT AND BONE MARROW EMBOLISM IN AIRCRAFT ACCIDENT VICTIMS ANTHONY R. BIERREAND T. D. KOELMEYER Department of Pathology, University oj Auckland School of Medicine, Auckland, New Zealand
Summary On 28 November 1979, an Air New Zealand DClO aircraft crashed into Mt Erebus, Antarctica with the loss of 257 passengers and crew. Postmortem examinations were carried out on 231 victims in Auckland, 4641 kilometres north of the crash site, and lung tissue was present in 205 cases. Pulmonary fat emboli were present in 134 cases (65%), pulmonary bone marrow emboli in 60 (29%) and pulmonary edema in 76 cases (37%). Clear relationships were demonstrated, firstly between the extent of fat and bone marrow embolism, secondly between the extent of fat and bone marrow embolism and the presence of pulmonary edema, and thirdly between the extent of fat and bone marrow embolism and the extent of cardiovascular damage. It was apparent that death had occurred immediately following impact, and the extent of fat and bone marrow embolism varied inversely with the severity of the injuries found. The most severely injured victims were those seated in the rear cabin of the aircraft suggesting that this was the site of impact with the ground. Our studies show that pulmonary fat embolism occurs very rapidly after severe injury and is followed by increasing numbers of fat and bone marrow emboli depending on the nature of the mortal injuries. Key words: embolism, fat, bone marrow, pulmonary, aircraft accidents. fractures, forensic medicine
INTRODUCTION The presence of fat and bone marrow emboli in lung tissue following trauma t o bones has been well documented.'-5 Fat and bone marrow emboli are thought to originate at the site of trauma and especially from the injured marrow of fractured bones.6 Globules of fat released from ruptured fat cells gain access to the circulation through torn venules as a result of a local shift in the differential between extravascular and intravascular pressures. It has been demonstrated that extravascular pressure greater than intravascular pressure within the marrow of fractured bones permits entry of fat globules and fragments of bone marrow into the c i r c ~ l a t i o n . ~
Pulmonary fat embolism occurs very rapidly after injury6.*. and when death follows shortly after injury, pulmonary fat and bone marrow emboli serve as markers for antemortem injury to bone." Mason" reported finding pulmonary fat embolism in 247; and pulmonary bone marrow embolism in 2 1 x of 3 1 1 victims of a number of separate aircraft accidents who were thought to have died immediately. The aims of this investigation were firstly, to establish the incidence of fat and bone marrow embolism in the lungs of a large group of severely injured individuals all of whom had been killed instantly, and secondly, to assess the role that study of pulmonary fat and bone marrow embolism may play in the reconstruction of an aircraft accident involving a large number of fatalities.
MATERIALS AND METHODS On 28 November 1979 an Air New Zealand DClO aircraft on a scenic flight crashed into the slopes of Mt Erebus. an active volcano on Ross Island, Antarctica. There were no survivors amongst the 257 passengers and crew on board. Disintegration ofthe aircraft was virtually complete with only the tail section and a small portion of fuselage readily recognizable. Wreckage and bodies were spread over an area measuring 570 metres by 120 metres indicating a severe force of impact. Two-hundred-and-thirty-one bodies were recovered, and postmortem examinations were carried out in Auckland, 4641 kilometres north of the crash site, on all of these as part of the identification procedure." All showed severe injuries ranging from almost total disintegration of the body to those which showed significant internal damage, such as fracture dislocation of the cervical vertebrae, with relatively few external signs of injury. All suffered bony fractures. Coroner's inquests into these deaths established that death followed immediately after impact in all cases.I2 Postmortem examinations were not carried out on 26 of the victims either because no body was recovered or the extent of injury was so severe that an adequate examination was not possible. Lung tissue was present in 205 of the 231 victims subjected t o postmortem examination. Twelve random blocks of lung tissue each measuring approximately 2 x 1 cm were obtained from each of the 205 victims, and were fixed by immersion in loo,, neutral formal saline. Six blocks were dehydrated in alcohol, cleared in xylol, and impregnated and embedded in paraffin wax. Sections 5p thick were cut from each of the remaining 6 blocks and stained either with oil red 0 or Sudan 111 and IV. Only fat globules which wereclearlyintravascular and deformed into elongated or sausage shaped ovals were identified as fat emboli. Free fat globules within lung tissue were excluded.
132
Pathology (1983). 15, April
BIERRE & KOELMEYER
A system (Table 1) was devised to assess objectively the extent of pulmonary fat embolism. The extent of pulmonary bone marrow embolism was assessed using the index of Masonlo (Table 2).
TABLE1 Grade 0 Grade 1 Grade 2 Grade 3 LPF
=
Q
The system of classification of the extent of pulmonary fat embolism (LPF = low power field) No emboli found Less than 6 emboli/lO LPF 6 to 35 emboli/lO L P F Greater than 35 emboli/lOLPF
43.75~
Type A Classification of slide Equivocal and acceptable Positive 1-2 emboli Positive 3-5 emboli Positive 6 + emboli
Score 1 point 2 points 4 points 6 points
Notes: n = number of slides examined A score of 1 4 = mildly positive. 5 and above = markedly positive.
The extent of pulmonary alveolar edema was also recorded. Alveolar edema was defined as the presence of pink finely granular proteinaceous material which was seen in more than 10 alveoli in 2 microscopic low of each of the 6 blocks of lung tissue power fields (LPF = 43.75~) ardined with hematoxylin and eosin. The presence or absence of lacerations of the heart or aorta was recorded and compared with the extent of pulmonary fat and bone marrow embolism in each case. The injuries seen in the victims were divided into 3 groups on the basis that the extent of injuries reflected the severity of the force applied. The three groups are illustrated in Fig. 1, as Type A, Type B, and Type C. The extent of pulmonary fat and bone marrow embolism in those people who were positively identified wascompared with the position of the seat assigned to each person o n the aircraft.
Combinations of fractures of Spine Pelvis Thigh Leg Ankle Skull Ribs .f Sofl Tissue Injury
Type A plus 1-2 limbs amputated f decapitation
Type c Type A & B plus further injuries
FIG. 1 Classification of the severity of injury
TABLE3 The incidence of pulmonary fat embolism Fat embolism no.
(7;)
Total
Grade 1
Grade 2
Grade 3
134 (65)
52 (25)
51 (25)
31 (15)
TABLE4
The incidence of pulmonary bone marrow embolism Bone marrow embolism no.
(06)
Total
Mildly positive
Markedly positive
60 (29)
32 (16)
28 (14)
RESULTS The incidence of pulmonary fat and bone marrow embolism in the 205 cases studied is shown in Tables 3 and 4. Figure 2 shows the relationship between pulmonary fat and bone marrow embolism. Bone marrow emboli were not found without fat emboli. As the extent of fat embolism increased, so did the extent of bone marrow embolism. All those cases with bone marrow embolism and grade 1 fat embolism had mildly positive bone marrow embolism, whereas among those with bone marrow embolism and grade 3 fat embolism only 38% (9) had mildly positive bone marrow embolism, and 637; (1 5) had markedly positive bone marrow embolism. Pulmonary edema was present in 76 cases (37%). Of those without fat emboli, 11% had pulmonary edema, whereas pulmonary edema was present in 37% of those with grade 1 fat embolism, 49% with grade 3 fat
Type
embolism, and 73% of those with bone marrow embolism. In Table 5 the extent of damage to the cardiovascular system is correlated with the presence or absence of pulmonary fat and bone marrow emboli. Those cases with intact cardiovascular systems had 4 times the incidence of bone marrow embolism and 1.75 times the incidence of fat embolism compared with those with lacerations of the heart and aorta. Forty-nine per cent of cases with lacerations of the heart or aorta had some fat emboli present but of these 50% had grade 1 fat embolism and only 11% had grade 3 fat embolism. One case in
133 with grade 2 or 3 fat embolism or bone marrow embolism. Of those cases with no lung tissue present 70", had type C pattern of injury. The extent of pulmonary fat and bone marrow embolism in each case and the seating position of that person are shown in Fig. 3. Of the 205 cases studied, 18 were crew members, and their positions at the time of impact could not be ascertained. Seven cases were not identified and so could not be assigned a seat number. N o fat or bone marrow emboli were seen in any of these 7 cases. It was possible to assign seat numbers to the remaining 180 of those studied. In the front cabin of the aircraft results were obtained for 28 of the 30 seats. Fat embolism grade 2, or grade 3 or bone marrow embolism was present in 61",, (17), fat embolism grade 1 in 25";, ( 7 ) ,and in 14'" (4) no fat emboli were present. In the middle cabin results were obtained for 66 of the 79 seats. Fat embolism grade 2 or grade 3 or FAT A N D BONE M A R R O W EMBOLISM
Bone Marrow Embolism
a
Markedly positive Mildly positive Total
Number Cases
1 ,m, .:.:.>:
5
........ .:.:.:.: ........ .... ........ .... .... .......*
~
Fat Embolism Grade
FIG. 2 Comparison of the extent of pulmonary fat embolism and the extent of pulmonary bone marrow embolism TABLE5
Comparison of the presence of pulmonary fat and bone marrow embolism and the presence of damage to the cardiovascular system
Heart or aorta
!
Total no. ('/")
I
Intact Lacerated
~
1
90(44) 115 (56)
Embolism absent no. ("/d 13 (14)
59 (51)
no. ("J
1
77 (86) 56 (49)
which the heart was absent at postmortem examination had grade 2 fat embolism and markedly positive bone marrow embolism. In Table 6 the extent of pulmonary fat embolism and the presence of pulmonary bone marrow embolism are compared with the severity of injury. The distribution of injuries seen in the 26 cases in which no lung tissue was present at postmortem examination is also recorded. These data show that, among cases without fat emboli or with only grade 1 fat embolism, a greater proportion had type B and type C patterns of injury than among cases TABLE6
Comparison of the severity of injury with the extent of pulmonary fat embolism, and the presence of pulmonary bone marrow embolism in 205 cases. The severity of injury seen in those cases with no lung tissue present has been included
Embolism extent Type A Fat embolism Grade 0 Grade 1 Grade 2 Grade 3
Severity of Injury Type B. Type C
'Iu
Bone marrow embolism ":,
No lung tissue present 5" (26 cases)
Bone Marrow embolism no. ("J
embolism
63 75 94 94
21 23 6 6
16
98
2
0
2 0 0
1
45 (50) 14 (12)
bone marrow embolism was present in 62",, (41), fat embolism grade 1 in 14", (9), and no fat emboli were present in 24",, (16). In the rear cabin, results were obtained for 86 of the 128 seats. Fat embolism grade 2 or grade 3 or bone marrow embolism was present in 26", (22), fat embolism grade 1 in 30"" (26), and no fat emboli were present in 44% (38). Of the 26 cases in which no lung tissue was found 7 were identified. Six were passengers, and all were seated in the rear cabin of the aircraft (Fig. 3). Four of these passengershad type C pattern of injury and 2 had type A pattern of injury
DISCUSSION This investigation has shown that fat and bone marrow emboli are found in the lungs of severely injured individuals thought to have been killed instantly. It has also demonstrated a clear relationship. firstly between the extent of fat embolism and the extent of bone marrow embolism; secondly, between the extent of fat and bone marrow embolism and the presence of pulmonary edema; and thirdly between the extent of fat and bone marrow embolism and the presence or absence of cardiovascular damage. The finding of pulmonary fat and bone marrow embolism in the victims of this aircraft crash supports the
134
Pathology (1983), 15, April
BIERRE & KOELMEYER
~ t ~ ~ ~ Grade ' l 2-3 s m Fat Embolism Grade 1
No Lung Tissue Present
nunidentified
NO Fot Embolism
FIG. 3 Comparison of the extent of pulmonary fat embolism and the presence of pulmonary bone marrow embolism with the seating plan of the aircraft
assertion that fat and bone marrow embolism occurs very rapidly, certainly within a few seconds of injury. The relationship found between pulmonary fat embolism and bone marrow embolism in severely injured individuals thought to have been killed instantly indicates that, if bone marrow embolism is present, one should also be able to demonstrate fat emboli, and that the more extensive the fat embolism the more likely that bone marrow embolism will be present. The finding that the incidence of pulmonary edema increases with the extent of pulmonary fat embolism and is high in the presence of pulmonary bone marrow embolism supports the concept that the production of emboli is time dependent. Pulmonary emboli and edema are seen only if cardiovascular circulation is present following bony injury, and both increase in extent if the circulation persists. The anomalous cases that had pulmonary fat embolism with lacerations to the heart or aorta may be explained on the basis of multiple episodes of injury which were known to have occurred in this aircraft crash. l 3 A clear relationship has also been demonstrated between the extent of pulmonary fat embolism and the presence of bone marrow embolism, and the severity of injury. Those with fat embolism grade 2 or 3 or with bone marrow embolism were found to be less severely injured than those with fat embolism grade 1 or no fat embolism. Thus where a large number of individuals were subjected to the same force, it is possible to use the extent of pulmonary fat and bone marrow embolism as an objective indicator of the severity of injury. Comparison of the extent of pulmonary fat embolism and the presence of bone marrow embolism with the seating plan of the aircraft indicates that more of the severely injured passengers occupied the seats in the rear cabin of the aircraft than in the front and middle cabins. This conclusion is supported by the presence in the rear cabin of those positively identified passengers in whom no lung tissue was present, the majority of whom had type C pattern of injury. It was evident from the postmortem examinations that a meal had been served shortly before the crash occurred, providing circumstantial evidence
that the passengers would have been seated in or close to their allotted seats. If the greatest force were applied to the aircraft at the point and time of initial impact, these findings suggest that the rear section of the aircraft hit the ground first. The same conclusion was reached by aircraft accident investigators following inspection of the crash site and analysis of the digital flight data r e ~ 0 r d e r . lIf~ the rear section of the aircraft was the point of impact on the mountain slope, this indicates that the aircraft was attempting to gain altitude at the moment of impact. This study has shown that the production of fat embolism is closely related to that of bone marrow embolism, and that both are time dependent and correlated with a number of variables such as an intact cardiovascular system. It would appear that following severe body injury, in those individuals thought to have been killed instantly, fat embolism to the lungs occurs very rapidly and, if time permits, is followed by increasing numbers of fat emboli and bone marrow emboli, all within a few seconds of injury. In this aircraft accident the victims died as a result of the impact and not from subsequent burns. The rear section ofthe aircraft was the site ofinitial impact with the ground. In these circumstances study of the presence and extent of pulmonary fat and bone marrow embolism in the victims may provide much information regarding the details of an aircraft accident and may be of particular importance when the flight data recorder is unavailable to investigators.
ACKNOWLEDGEMENTS The authors wish to thank Associrite Professor F. J. Cairns, Professor P. B. Herdson and Drs G . C. Hitchcock, W. M. I. Smeeton and B. J. L. Synek of the Department of Pathology, University of Auckland, School of Medicine for the use of postmortem material. We also wish to thank Mr R. Chippindale, Chief Inspector of Air Accidents, Ministry of Transport, Wellington, for permission to refer to Aircraft Accident Report No. 79-139. We are indebted to Associate Professor F. J. Cairns, Professor J. B. Gavin
FAT AND BONE MARROW EMBOLISM
and Professor P. B. Herdson for their advice and criticism of the manuscript. Address for correspondence: A.R.B., Department of Pathology, University of Auckland, School of Medicine, Private Bag, Auckland. New Zealand
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