laboratory and animal investigations 11I1,11~8~----------------------
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Experimental Polyacrylamide-induced Acute Injury in Rat Lung* Armando E. Fraire, M.D., F.C.C.E;t lmram Shahab, M.D.;+ S. Donald Greenberg, M.D., F.C.C.E;§ Amal jubran, M.D.;II and Matthew NoaU, Ph.D.~
We recently reported the 6rst case of accidental aspiration of polyacrylamide occurring in a 26-year-old man. The patient developed severe airway obstruction and parenchymal lung damage and died. Autopsy revealed numerous polyacrylamide particles in his lungs, as well as extensive bronchiolar and alveolar damage. Gas chromatographic and mass spectrometric assessment of the lung tissue failed to reveal polyacrylamide activity, although assessment of the suspending solvent of the polyacrylamide showed a pattern characteristic of an aliphatic hydrocarbon mixture with a prominent dodecane peak. This experimental study was performed to determine the nature and extent of damage to rat bronchial and alveolar epithelia foUowing endotracheal instillation of polyacrylamide, hydrocarbon mixture (petroleum distillate), dodecane (C.sH.), or normal saline. The rat lungs were examined grossly and microscopically 10 min and 24, 72, and 96 h after endotracheal instillation, following inOation and fixation with 10 percent buffered formaldehyde. Gross examination revealed con-
gested, mottled visceral pleural surfaces in the rats treated with polyacrylamide and dodecane. There were DO pleural exudates or effusions. Microscopically, vascular engorgement, bronchiolitis, and focal pneumonia were observed. Vascular engorgement was most pronounced at 72 to 96 h in rat lungs treated with polyacrylamide and dodecaoe and was moderate at !4 b in rats treated with petroleum distillate. Focal organizing pneumonia was marked at 96 h in rats treated with petroleum distillate, at 72 h in those treated with polyacrylamide, and at 24 h in those treated with dodecane. The saline-treated control animals showed DO change. Our 6ndings suggest that polyacrylamide, dodecane, and petroleum distillate are strong irritants to the airways. However, a direct obstructive/mechanical effect or the polyacrylamide upon the airway has not been excluded. Airway exposure to polyacrylamide may result in lung injury secondary to the polyacrylamide itself, its suspending agents, or both. (Che.t 1992; 102:1591-94)
Nute lung injury secondary to aspiration of polyacrylamide (a synthetic polymer used widely in textile and paper industries and in the management of chemical waste) has not been well characterized. 1 We previously reported the case of a 26-year-old man who died after he aspirated polyacrylamide while cleaning a transport tank truck." At autopsy, there were numerous polyacrylamide particles in the lungs, along with bronchiolar and alveolar damage. Chemical analysis of the lung tissue by means of gas chromatography and mass spectrometry registered an aliphatic hydrocarbon mixture (interpreted as a suspending agent) with a prominent dodecane (C12Hi6) peale.
However, polyacrylamide did not register by gas chromatographic and mass spectrophotometric analysis, suggesting a chemically inert nature. Although the immediate cause of death of the patient was hypoxic brain damage, the clinical course and the histopathologic findings at autopsy demonstrated that aspiration of polyacrylamide can cause pulmonary damage. Our former case report further illustrated the need for display of warnings in the workplace to prevent industrial accidents and highlighted the lack of medical knowledge regarding the adverse pulmonary effects of polyacrylamide. This deficiency of knowledge initiated our experimental studies of the histopathologic consequences of its aspiration. Therefore, this experimental study in rat lung was undertaken to determine the nature and extent of acute injury to rat bronchiolar and alveolar epithelia following endotracheal instillation of polyacrylamide, hydrocarbon mixture (petroleum distillate), dodecane, or normal saline solution.
*From the Department of Pathology, Baylor College of Medicine, I-Iouston, (Drs Fraire, Shahab, Greenberg, and Noall), and the Department of Pulmonary and Critical Care Medicine, Edward Hines Veterans Administration Hospital, Loyola University Stritch School of Medicine, Hines, Illinois (Dr lubran). tCurrently Associate Professor of Patho ogy, University of Massachusetts Medical Center, Worcester. iSenior Resident in Pathology § Professor of Pathology. IIAssistant Professor of Pulmonary Medicine, Loyola University Stritch School of Medicine, Maywood, Illinois ~Associate Professor (Retired) of Pathology. Supported in part by grant 19-372250-145110 from the Baylor Pulmonary Pathology Research Fund. Reprint requests: Dr. Fraire, Department of lbthology, University of Massachusetts Medical Center; Worcester01655
MATERIALS AND METHODS
Surgical Procedure Female Fischer 344 specific pathogen-free rats (n = 16), weighing CHEST I 102 I 5 I NOVEMBER, 1992
1591
200 to 220 gm , were used in this expe rime nt. The rats were anesthetized intramuscularly with a solution containing ketamine , 42 m~; xylazine, 8.6 rng: and acepromazine , 1.4 mg/ml, at a dose of 0.5 rnl/kg of body weight. A 2-cm surgical incision was made over the anterior portion of tile neck to expose tile trachea. A eommereially available preparation of polyacrylamide (Callaway 4330-K) ohtained from tile human exposure case , petroleum distillate (Delta Distributors), dodecane (Aldrich), and normal saline (Travenol), in doses of 200 ILl (equivalent of 0.2 of normal [0.60 to 1.25 mil rat tidal volume)' were given by direct endotracheal instillation. To facilitate tile instillation of polyacrylamide into the airwa y. the polyacrylamide was vortex-mixed with an equal amount of normal saline solution for 3 to 5 min in order to transform the gel into a semiliquid geiatinous substance capable of running along the wall of a glass tube when inverted . Once this condition was attained. the hydrated polyacrylam ide was instilled directly into tile trachea through a large-bore cannula. Postoperatively. tile rats were kept warm by use of heating pads and were ~iven manual ventilatory support until stahle. The surgical incision was closed wit II 3.0 coated Vicryl (Ethicon, Somerville. NJ). and tile animals were returned to their cages lilr observation. Tile rats were then killed at 10 min or 24 . 72. 96 , or 120 II followin!!: tile endotracheal instillation. by exposure to carbon dioxide within a CO, chamber (Carbothanasia; Humane Causes Inc . New York).
•
lbthologic Studies The chest cavity was opened by means of a standard Y-shaped incision , and the anterior chest plate was removed . With the lungs in situ. the trachea was cannulated and pressure-inflated with 10 percent buffered formaldehyde . The trachea was then sutureligated. and the lungs and heart were removed en bloc and suspended for at least 24 h in a buffered formaldehyde solution prior to embedding in paraffin . Lung sections 4 to 5 ILm thick. were stained with hematoxylin-eosin. The stained lung tissue sections of rat lung were studied microscopically and evaluated for vascular congestion, bronchiolttis, and acute pneumonia. An index of severity. ranging from 0 (absent) to + + + (severe), was used to evaluate the extent of the histopathologic changes. RESULTS
Four of the 16 rats were used as saline controls. The remaining 12 rats were divided into three groups of four rats each. Polyacrylamide was administered by tracheal instillation to the first group of four rats; petroleum distillate, to the second; dodecane, to the third . None of the saline controls died during or after the endotracheal instillation. The saline controls were killed at 15 min and 24, 96, and 120 h after endotracheal instillation. Three of the four polyacrylamide-treated rats survived the operative procedure and were killed at 10 min, 24 h, and 72 h, respectively. There were only two survivors among the four rats treated with petroleum distillate; they were killed at 10 min and 96 h, respectively. Three of the four dodecane-treated rats survived; they were killed at 10 min, 24 h, and 72 h . The overall mortality for the non-saline-treated rats was 4 of 12 (33.3 percent), with most of the acute deaths occurring within 2 to 3 min after endotracheal instillation. The lungs of the saline-treated controls showed no gross changes. The principal gross change in the polyacrylamide-treated lungs was a mottled, 1592
FIGURE 1. Posterior aspect of both lungs, showing mottled hemorrhagic appearance of visceral pleural surfaces after instillation of polyacrylamide.
focally hemorrhagic appearance (Fig 1). Similar, but less pronounced, changes were seen in the petroleum distillate-treated and dodecane-treated groups. None of the rats showed pleural effusions or pleural exudates. Microscopically, capillary congestion was seen in all
FIGURE 2. Polyacrylamide-treated rat lung, showing mild but diffuse congestion manifested by dilated capillaries in interalveolar septa. This capillary congestion was also observed in rats treated with saline . dodecane, and petroleum distillate (hematoxylin-eosin, original magnification x 125).
Experimental Polyacrytamlde-nduced Acute Injury in
Rat lung (FrBiffl et til)
Table I-ShoTt-term Hiatopathologic Effecta of Saline, Polyacrylamide, IWroleum Diatillate, and lJ
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Experimental Polyacrylamide-induced Acute Injury in Rat Lung* Armando E. Fraire, M.D., F.C.C.E;t lmram Shahab, M.D.;+ S. Donald Greenberg, M.D., F.C.C.E;§ Amal jubran, M.D.;II and Matthew NoaU, Ph.D.~
We recently reported the 6rst case of accidental aspiration of polyacrylamide occurring in a 26-year-old man. The patient developed severe airway obstruction and parenchymal lung damage and died. Autopsy revealed numerous polyacrylamide particles in his lungs, as well as extensive bronchiolar and alveolar damage. Gas chromatographic and mass spectrometric assessment of the lung tissue failed to reveal polyacrylamide activity, although assessment of the suspending solvent of the polyacrylamide showed a pattern characteristic of an aliphatic hydrocarbon mixture with a prominent dodecane peak. This experimental study was performed to determine the nature and extent of damage to rat bronchial and alveolar epithelia foUowing endotracheal instillation of polyacrylamide, hydrocarbon mixture (petroleum distillate), dodecane (C.sH.), or normal saline. The rat lungs were examined grossly and microscopically 10 min and 24, 72, and 96 h after endotracheal instillation, following inOation and fixation with 10 percent buffered formaldehyde. Gross examination revealed con-
gested, mottled visceral pleural surfaces in the rats treated with polyacrylamide and dodecane. There were DO pleural exudates or effusions. Microscopically, vascular engorgement, bronchiolitis, and focal pneumonia were observed. Vascular engorgement was most pronounced at 72 to 96 h in rat lungs treated with polyacrylamide and dodecaoe and was moderate at !4 b in rats treated with petroleum distillate. Focal organizing pneumonia was marked at 96 h in rats treated with petroleum distillate, at 72 h in those treated with polyacrylamide, and at 24 h in those treated with dodecane. The saline-treated control animals showed DO change. Our 6ndings suggest that polyacrylamide, dodecane, and petroleum distillate are strong irritants to the airways. However, a direct obstructive/mechanical effect or the polyacrylamide upon the airway has not been excluded. Airway exposure to polyacrylamide may result in lung injury secondary to the polyacrylamide itself, its suspending agents, or both. (Che.t 1992; 102:1591-94)
Nute lung injury secondary to aspiration of polyacrylamide (a synthetic polymer used widely in textile and paper industries and in the management of chemical waste) has not been well characterized. 1 We previously reported the case of a 26-year-old man who died after he aspirated polyacrylamide while cleaning a transport tank truck." At autopsy, there were numerous polyacrylamide particles in the lungs, along with bronchiolar and alveolar damage. Chemical analysis of the lung tissue by means of gas chromatography and mass spectrometry registered an aliphatic hydrocarbon mixture (interpreted as a suspending agent) with a prominent dodecane (C12Hi6) peale.
However, polyacrylamide did not register by gas chromatographic and mass spectrophotometric analysis, suggesting a chemically inert nature. Although the immediate cause of death of the patient was hypoxic brain damage, the clinical course and the histopathologic findings at autopsy demonstrated that aspiration of polyacrylamide can cause pulmonary damage. Our former case report further illustrated the need for display of warnings in the workplace to prevent industrial accidents and highlighted the lack of medical knowledge regarding the adverse pulmonary effects of polyacrylamide. This deficiency of knowledge initiated our experimental studies of the histopathologic consequences of its aspiration. Therefore, this experimental study in rat lung was undertaken to determine the nature and extent of acute injury to rat bronchiolar and alveolar epithelia following endotracheal instillation of polyacrylamide, hydrocarbon mixture (petroleum distillate), dodecane, or normal saline solution.
*From the Department of Pathology, Baylor College of Medicine, I-Iouston, (Drs Fraire, Shahab, Greenberg, and Noall), and the Department of Pulmonary and Critical Care Medicine, Edward Hines Veterans Administration Hospital, Loyola University Stritch School of Medicine, Hines, Illinois (Dr lubran). tCurrently Associate Professor of Patho ogy, University of Massachusetts Medical Center, Worcester. iSenior Resident in Pathology § Professor of Pathology. IIAssistant Professor of Pulmonary Medicine, Loyola University Stritch School of Medicine, Maywood, Illinois ~Associate Professor (Retired) of Pathology. Supported in part by grant 19-372250-145110 from the Baylor Pulmonary Pathology Research Fund. Reprint requests: Dr. Fraire, Department of lbthology, University of Massachusetts Medical Center; Worcester01655
MATERIALS AND METHODS
Surgical Procedure Female Fischer 344 specific pathogen-free rats (n = 16), weighing CHEST I 102 I 5 I NOVEMBER, 1992
1591
200 to 220 gm , were used in this expe rime nt. The rats were anesthetized intramuscularly with a solution containing ketamine , 42 m~; xylazine, 8.6 rng: and acepromazine , 1.4 mg/ml, at a dose of 0.5 rnl/kg of body weight. A 2-cm surgical incision was made over the anterior portion of tile neck to expose tile trachea. A eommereially available preparation of polyacrylamide (Callaway 4330-K) ohtained from tile human exposure case , petroleum distillate (Delta Distributors), dodecane (Aldrich), and normal saline (Travenol), in doses of 200 ILl (equivalent of 0.2 of normal [0.60 to 1.25 mil rat tidal volume)' were given by direct endotracheal instillation. To facilitate tile instillation of polyacrylamide into the airwa y. the polyacrylamide was vortex-mixed with an equal amount of normal saline solution for 3 to 5 min in order to transform the gel into a semiliquid geiatinous substance capable of running along the wall of a glass tube when inverted . Once this condition was attained. the hydrated polyacrylam ide was instilled directly into tile trachea through a large-bore cannula. Postoperatively. tile rats were kept warm by use of heating pads and were ~iven manual ventilatory support until stahle. The surgical incision was closed wit II 3.0 coated Vicryl (Ethicon, Somerville. NJ). and tile animals were returned to their cages lilr observation. Tile rats were then killed at 10 min or 24 . 72. 96 , or 120 II followin!!: tile endotracheal instillation. by exposure to carbon dioxide within a CO, chamber (Carbothanasia; Humane Causes Inc . New York).
•
lbthologic Studies The chest cavity was opened by means of a standard Y-shaped incision , and the anterior chest plate was removed . With the lungs in situ. the trachea was cannulated and pressure-inflated with 10 percent buffered formaldehyde . The trachea was then sutureligated. and the lungs and heart were removed en bloc and suspended for at least 24 h in a buffered formaldehyde solution prior to embedding in paraffin . Lung sections 4 to 5 ILm thick. were stained with hematoxylin-eosin. The stained lung tissue sections of rat lung were studied microscopically and evaluated for vascular congestion, bronchiolttis, and acute pneumonia. An index of severity. ranging from 0 (absent) to + + + (severe), was used to evaluate the extent of the histopathologic changes. RESULTS
Four of the 16 rats were used as saline controls. The remaining 12 rats were divided into three groups of four rats each. Polyacrylamide was administered by tracheal instillation to the first group of four rats; petroleum distillate, to the second; dodecane, to the third . None of the saline controls died during or after the endotracheal instillation. The saline controls were killed at 15 min and 24, 96, and 120 h after endotracheal instillation. Three of the four polyacrylamide-treated rats survived the operative procedure and were killed at 10 min, 24 h, and 72 h, respectively. There were only two survivors among the four rats treated with petroleum distillate; they were killed at 10 min and 96 h, respectively. Three of the four dodecane-treated rats survived; they were killed at 10 min, 24 h, and 72 h . The overall mortality for the non-saline-treated rats was 4 of 12 (33.3 percent), with most of the acute deaths occurring within 2 to 3 min after endotracheal instillation. The lungs of the saline-treated controls showed no gross changes. The principal gross change in the polyacrylamide-treated lungs was a mottled, 1592
FIGURE 1. Posterior aspect of both lungs, showing mottled hemorrhagic appearance of visceral pleural surfaces after instillation of polyacrylamide.
focally hemorrhagic appearance (Fig 1). Similar, but less pronounced, changes were seen in the petroleum distillate-treated and dodecane-treated groups. None of the rats showed pleural effusions or pleural exudates. Microscopically, capillary congestion was seen in all
FIGURE 2. Polyacrylamide-treated rat lung, showing mild but diffuse congestion manifested by dilated capillaries in interalveolar septa. This capillary congestion was also observed in rats treated with saline . dodecane, and petroleum distillate (hematoxylin-eosin, original magnification x 125).
Experimental Polyacrytamlde-nduced Acute Injury in
Rat lung (FrBiffl et til)
Table I-ShoTt-term Hiatopathologic Effecta of Saline, Polyacrylamide, IWroleum Diatillate, and lJ
