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Home , Hypercapnia

CE Article #2 m o c . k

c Canine o t s r e t t u h S

/ Carrie E. Goldkamp, VMD a d z a Michael Schaer, DVM, DACVIM, DACVECC a G y l r

e University of Florida b m i K 8 0 0 2

© ABSTRACT: Drowning is potentially fatal. Physiologic responses to aspiration of water differ according to whether the water is salt or fresh; whether these responses are significant depends on the volume of fluid aspirated. efforts should be started at the scene of the accident. therapy is essential . Many patients require continuous positive airway or positive end-expiratory pressure to reverse hypoxemia. Physiologic responses induced by ice-water submersion can be protective during the initial insult. The prognosis for submersion injuries is guarded and is influenced by several variables.

rowning is defined as “the process of presumed that in these cases, occurred experiencing respiratory impairment before the person entered the water or was due from submersion or immersion in liq - to a sudden cessation of circulation without D1 uid.” The terms near-drowning and drowning aspiration of water. Active aspiration is required were previously used to classify outcomes with for water to enter the . 6 A conscious, sub - regard to survival. 2 However, these terms have merged person usually aspirates water as he or been replaced with death , morbidity , and no mor - she struggles in , which is associated with bidity following a drowning episode. 1 In 2004, massive catecholamine release. 7 Conversely, drowning was the second most common cause when a person loses consciousness before sub - of accidental death in children younger than 14 mersion/immersion (e.g., as a result of seizure), years in the United States, with approximately he or she quickly sinks, and there may be no five times as many children of this age sustain - catecholamine release. 7 The terms dry drowning ing morbidity from drowning. 3 and wet drowning are no longer used. 1 It was previously believed that 85% to 90% of Most of the initial studies on the pathophysi - humans who drown experience wet drowning , ology of submersion/immersion injuries and the in which a large volume of water is aspirated, treatments for morbidity were conducted in and that 10% to 15% experience dry drowning , dogs. Although the prevalence of drowning in in which little or no water is aspirated but dogs does not reach that in children, there are severe causes severe hypoxemia numerous unpublished reports of submersion/ and eventual death. 4 A more recent study, 5 immersion injuries in dogs. Canine drowning however, found that less than has been associated with falling into water, 2% of human from swimming accidents, intentional immersion, drowning were “dry.” It is now seizures near water, and falling through ice. 8 This •Take CE tests article reviews the human literature based on the aDr. Schaer discloses that he has re- canine model, describes the pathophysiology of • See full-text articles ceived financial support from VCA Antech and from Novartis Animal drowning, and presents the treatment and prog - CompendiumVet.com Health. nosis for the associated morbidity.

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PATHOPHYSIOLOGY hydrophilic material produced by type II pneumocytes Initial Injury (specialized cells in the alveoli). Normally, the alveoli are The earliest studies in dogs investigated the pathophys - lined with , which, by decreasing the surface iology of freshwater versus saltwater drowning. Although tension of water, prevents their collapse during drowning in either type of water can cause severe, poten - deflation and promotes lung compliance, or ease of lung tially fatal hypoxemia, differences in the volume and com - inflation or expansion. Freshwater interferes with the position of the fluid aspirated induce distinct physiologic ionic composition of surfactant, thereby altering its sur - responses. There is no evidence that chlorinated water has face tension properties. 12 The alveoli readily collapse, and any effect on the pathophysiology or outcome. 9–12 right-to-left intrapulmonary shunting, in which blood The presence of liquid in the oropharynx or larynx flows from the right side of the circulation to the left side usually triggers a vagally mediated laryngospasm, 1,13,14 without ever coming into contact with a functional followed by reflex vasoconstriction in the lungs and exchange unit, occurs. 10 The lungs also become less com - immediate pulmonary hypertension. 13 Freshwater, pliant. Conversely, salt water washes out some surfactant because its tonicity is lower than that of the body’s extra - but leaves the remaining surfactant intact without chang - cellular fluid, is rapidly absorbed from the alveoli ing its properties. 12 Because hypertonic through the alveolar –capillary basement membrane into salt water pulls fluid into the alveoli, an intrapulmonary the intravascular space. 15 Blood volume and extracellular shunt again results. The alveoli are perfused but, because electrolyte immediately change secondary they are filled with fluid, ventilation does not occur. 10

Cardiopulmonary efforts, including external cardiac massage and mouth-to-nose ventilation, should be started at the scene of the accident. to a dilutional effect; hyponatremia and hypervolemia Lung Damage have consistently been observed moments after aspira - Both types of fluid directly damage the type I and type II tion of a significant quantity of freshwater. 9,13,15–18 The pneumocytes of the alveolar epithelium and the pulmonary hypotonicity of freshwater can also cause intravascular capillary endothelial cells, causing inflammation, transuda - hemolysis with resultant hyperkalemia, hemoglobinemia, tion of protein-rich fluid into the alveolar space, and inter - and hemoglobinuria. 4,19 The hematocrit can increase, stitial and alveolar edema. 22 The mechanical barrier between presumably from swelling of erythrocytes. 9,15,19 However, the environment and the patient is disrupted, increasing unless the volume of freshwater aspirated is large (>22 susceptibility to infection through bacterial translocation. 23 ml/kg), these hematologic changes are rarely clinically Normal epithelial fluid and ion transport cannot occur, and significant. 9,15 In fact, by the time patients that have aspi - the production of surfactant is altered. 24 The alveo - rated freshwater present to a hospital, hypervolemia has lar–capillary basement membrane is exposed, leading to fur - often given way to hypovolemia due to redistribution of ther migration and activation of neutrophils and fluids and , 20 and electrolyte concentra - macrophages and increased inflammatory cytokine produc - tions are within normal ranges. 9,15 tion. 24 of the alveoli continues without ventilation, In contrast to freshwater, salt water has a higher increasing the shunt fraction. The resultant hypoxemia is tonicity than the body’s extracellular fluid and thus has unresponsive to increased oxygen content of inspired air due opposite effects. Salt water draws fluid from the to the totally obstructed alveoli or to shunting. The alveoli intravascular space through the alveolar–capillary base - collapse because of the loss of surfactant, and lung compli - ment membrane into the alveolar space. 21 Hypo- ance is decreased. This cascade of events is referred to as volemia, 21 a transient increase in plasma acute respiratory distress syndrome (ARDS ). 24 of extracellular electrolytes, 13,21 and increased pulmonary fluid volumes result. 13,16,21 Hypoxemia and In addition to their differences in tonicity, freshwater Right-to-left intrapulmonary shunting, decreased pul - and salt water have different effects on the chemical monary compliance, and ARDS cause a rapid decrease in properties of pulmonary surfactant, 12 a hydrophobic– arterial oxygen tension 10 ; the patient may also be unable to

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expire , causing . 4,25 Retrospective bacteria. If the material is an appropriate size, it may studies found that humans who drowned in freshwater or obstruct the smaller bronchi and bronchioles. 2 Severe salt water were consistently hypoxemic and acidotic. 4,9,10,15 pulmonary infection may also develop in dogs. In Metabolic acidosis in these patients is secondary to hypox - humans, airway obstruction has generally not been emia and lactic acidosis. 24 By the time the patient arrives at found to interfere with artificial ventilation, and severe the hospital, resuscitation efforts have usually been started infection rarely develops. 26 and ventilation has been improved. Therefore, hypercapnia and are not usually evident on blood gas ON-SITE RESUSCITATION measurements, but persistent hypoxemia is documented and Cardiopulmonary resuscitation efforts should be requires additional therapy. 9,13,23 started at the scene of the accident. Mouth-to-nose resuscitation should be commenced if the animal is Hemodynamic Effects apneic. 7 External cardiac massage should be performed The hemodynamic effects of drowning include if a heartbeat is not detected. 7 The drowned animal can decreased cardiac output, increased pulmonary capillary quickly be positioned to promote gravitational drainage wedge pressure (a reflection of left atrial pressure), and of fluid from the lungs; however, the rescuer should not increased pulmonary vascular resistance, all of which spend too much time on this effort because drainage has occur secondary to . 11,13 Hypoxemia, hypoten - not been found to affect outcome. 7,27 Freshwater is sion, and hemoglobinuria can lead to renal damage as absorbed quickly, so gravitational drainage may be more well. 17 Ventricular fibrillation may cause death. 15 logical in salt water submersion injuries. 7 Previous recommendations in humans included the Complications Heimlich maneuver to remove water from the lungs. 28 It Severe complications can result when the aspirated is now known that most humans who drown also swal - water is grossly contaminated with particulate matter or low substantial quantities of fluid. 7,29 The Heimlich 344 CE Canine Drowning

maneuver is currently only recommended when the air - TREATMENT way is blocked with solid material because abdominal thrusts can cause vomiting with aspiration of gastric con - When the patient arrives at the hospital, an intravenous tents, which compounds the damage to the lungs and catheter should be placed for vascular access. Electrocar - causes more severe pulmonary edema. 5,7,30 The Heimlich diography should be monitored and cardiac maneuver also delays the application of effective artificial treated appropriately. Oxygen therapy is of utmost impor - ventilation, compounding hypoxia. 30 Approximately 24% tance. 7 In humans, is started if the of humans who drown vomit, so in humans, the airway patient cannot maintain a Pa O2 of more than 90 mm Hg should be protected by appropriate positioning. 30 After despite a supplemental fraction of inspired oxygen con - 7 resuscitation efforts, animals that have drowned should centration (F IO 2) of 50% or if the patient is apneic. Cri - be wrapped in a warm blanket (if immediately available) teria for artificial in dogs are a Pa O2 of less and taken directly to a veterinary hospital. than 60 mm Hg with an F IO 2 greater than 50% or a Pa O2 32 of less than 40 mm Hg at any F IO 2. DIAGNOSIS The most effective treatment in reversing hypoxemia In animals, the diagnosis of drowning is usually made after a submersion injury is continuous positive airway based on the patient’s history at presentation. The pressure (CPAP) or positive end-expiratory pressure owner should be asked about the submersion/immersion (PEEP). 33–35 CPAP maintains positive pressure in the injury and the events preceding it. The interview should airways throughout respiration, and PEEP maintains take as little time as possible and should include ques - positive airway pressure in the airways during expiration tions about the type of water in which the animal and between breaths. The purpose of PEEP and CPAP

The most effective treatment in reversing hypoxemia after a submersion injury is continuous positive airway pressure or positive end -expiratory pressure. drowned (salt water or freshwater), the length of time is to keep the alveoli open at the end of expiration to the animal was under water, prior episodes of seizures or increase the functional residual capacity—the volume of syncope, and the possibility of accidental drug ingestion. gas in the lungs at the end of normal expiration—and to A detailed description of the resuscitation should be decrease intrapulmonary shunting. 32 Otherwise, the alve - recorded and should include information about the ani - oli collapse easily because of high surface tension due to mal’s level of consciousness, heart rate, respiratory rate, surfactant loss (after aspiration of all types of fluid) or and at rescue. damage (after aspiration of freshwater). 12 Keeping the A thorough physical examination should be performed. alveoli patent and ventilated and increasing functional Measurement of arterial blood gas is imperative; thoracic residual capacity decrease airway resistance and improve radiography, although important, is less critical. Radi - lung compliance. 12,32 Optimal PEEP or CPAP decreases ographic changes may lag behind clinical signs. 31 Radi - the work of , improves ventilation–perfusion ographically, an alveolar pattern is most prominent in the abnormalities, and minimizes intrapulmonary shunt - early stages after drowning, although strong interstitial ing. 33–35 Care should be taken to avoid excessive CPAP or and bronchial components can also be present. 31 Hyper - PEEP because it can impede venous return in an already inflation of the lungs may be seen because of increased volume-compromised patient and can cause respiratory efforts by the patient. 31 If initial treatment by overdistending healthy alveoli. 32,36 efforts are successful and ARDS does not develop, the The choice of which ventilation mode to use may alveolar pattern will resolve, leaving a mixed interstitial- depend on the type of fluid aspirated. Either CPAP bronchial pattern, and radiographic evidence of lung (with spontaneous respiration) or PEEP can effectively pathology will dissipate within 7 to 10 days of the drown - improve hypoxemia when salt water has been aspi - ing incident. 31 However, if the pulmonary disease worsens rated. 33–35 In cases of freshwater drowning, PEEP with despite initial treatment, the alveolar pattern will become controlled mechanical ventilation is usually needed to more severe, possibly indicating . 31 improve hypoxemia; CPAP with spontaneous respira -

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tion is frequently inadequate. 34,35 This is likely due to the method of treating humans who presented to the hospi - higher surface tension in the alveoli secondary to surfac - tal with neurologic abnormalities after drowning. One tant damage incurred by freshwater. 12 author 37,38 proposed categorizing patients who had In humans and animals being treated for drowning, it drowned based on their level of consciousness on pres - is recommended that PEEP be started at 5 cm H 2O, entation to the hospital and instituting “cerebral salvage” then increased by 2 to 3 cm H 2O until the Pa O2:F IO 2 therapy in them. He treated aggressively with continu - 7 ratio is at least 300 or until the F IO 2 can be decreased to ous dehydration with furosemide, controlled hyperventi - less than 60% while maintaining adequate arterial oxy - lation to minimize , to 32 gen tension. The F IO 2 should be reduced to less than decrease cerebral oxygen requirements, barbiturate 60% as soon as possible to avoid . 7,32 An to decrease intracranial pressure and for a “beneficial

FIO 2 of 1.0 for 48 to 72 hours has been shown to cause effect on neurons,” and continuous muscle paralysis to death in animals. 32 Supplemental oxygen should be con - prevent movement that might increase intracranial pres - tinued with or without CPAP or PEEP until the arterial sure. 37,38 Although initial publications 37,38 showed an oxygen tension is adequate. Although it takes approxi - increase in survival and a decrease in long-term neuro - mately 20 hours to regenerate surfactant, 34 in one study, logic deficits, subsequent studies 25,39 found some of the it took 3 to 7 days for Pa O2 to return to normal in dogs therapeutic methods to be detrimental. Intracranial that survived freshwater drowning. 33 pressure was elevated in patients with ischemic cerebral As previously mentioned, many dogs that drown are injury secondary to prolonged hypotension but not in hypovolemic secondary to pulmonary edema. Dogs that those with hypoxic cerebral injury, 39 suggesting that are being mechanically ventilated also may have dehydration is contraindicated. Hypothermia decreased decreased venous return. 36 Intravenous lactated Ringer’s the number of circulating neutrophils and their release was found to improve cardiovascular parame - from the bone marrow 39,40 and was associated with the ters in dogs that aspirated freshwater and were venti - development of . 39,41 It did not increase the survival

Although treatment with pentoxifylline may be beneficial in reducing indirect lung injury, there is no evidence that steroid or prophylactic antibiotic therapy improves the survival rate in drowned animals. lated mechanically with PEEP. 20 Mean arterial pressure, rate. 39 Although barbiturates may control intracranial cardiac output, central venous pressure, pulmonary cap - pressure, their use did not improve neurologic out - illary wedge pressure, and oxygen delivery increased come. 39 Treatment in humans is aimed at maintaining while systemic vascular resistance, pulmonary vascular cerebral perfusion pressure and adequate oxygenation to resistance, and arteriovenous oxygen content difference prevent further damage to vital organs 20 ; similar recom - decreased. 20 Intrapulmonary shunting was not affected mendations likely apply to dogs. 20 by appropriate amounts of intravenous fluids. Most There is no evidence that steroids improve the Pa O2, drowning patients have metabolic acidosis, 4,9,18,26 and in the degree of intrapulmonary shunting, or the survival humans it is recommended that metabolic acidosis be rate in dogs that aspirate freshwater. 42,43 Pulmonary treated if the pH is less than 7.1 to prevent further car - pathology was similar between dogs that did and did diovascular compromise. 16 Electrolytes, blood urea not receive steroids after aspiration of acidic fluid and , creatinine, glucose, and urine output should resultant aspiration pneumonitis. 43 Steroids have been also be monitored. 16 shown to interfere with the granulomatous response in rabbits after aspiration of gastric contents 44 ; therefore, Other Therapies the administration of steroids to drowned animals is not The main therapeutic goal after resuscitation in recommended. humans is the prevention of hypoxic neurologic injury. Prophylactic antibiotics have not been found to affect During the 1980s, controversy arose regarding the survival in drowned animals 36,45 and have been found to

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select for more resistant organisms if infection does cardic heart is susceptible to fibrillation. 7,50 If there is develop. 45 A better approach is to monitor for signs of true cardiopulmonary arrest, cardiopulmonary resuscita - infection. If the patient is febrile or has leukocytosis, or if tion should be continued, although hypothermic cytology of tracheal aspirates shows evidence of bacterial patients are relatively resistant to pharmacologic and infiltration, antibiotic therapy should be started while electrostimulatory therapy. 7 In humans, defibrillation by awaiting results of bacterial cultures and sensitivities. 26 electric shock is recommended if the patient presents in A recent study 46 in Japan found that a continuous-rate ventricular fibrillation with a core body temperature infusion of pentoxifylline reduced indirect lung injury greater than 85°F (29.4°C). 7 The patient should be (lung injury secondary to ARDS) in dogs after aspira - rewarmed, although it is not known whether the rapid - tion of freshwater. Pentoxifylline is a methylxanthine ity or method of warming affects survival. 7,16 In humans, derivative and a nonspecific phosphodiesterase inhibitor. use of warm water baths; warmed intravenous fluids, It was found to decrease the expression of intercellular blankets, and heating pads; and warm orogastric lavage adhesion molecule-1 (ICAM-1) mRNA. ICAM-1 is an to aggressively rewarm the patient is recommended immunoglobulin that is expressed on endothelial cells when the core body temperature is less than 85.1°F and neutrophils and is involved in the migration of neu - (29.5°C). 7 Heating pads should be used with caution in trophils into lung tissue. Histology of lung tissue from dogs because they can cause skin burns. When the dogs that received pentoxifylline showed a marked patient’s core temperature is between 85.1°F and 89.6°F decrease in neutrophil infiltration. Clinical studies (29.5°C and 32°C), slow, active rewarming with heating showing beneficial effects of pentoxifylline are necessary pads, warmed intravenous fluids, and warmed, humidi - before this treatment can be recommended. fied oxygen should be instituted. 7 When the rectal tem - β2 Agonists and methylxanthines, which are short- perature is greater than 89.6°F, rewarming at a rate of acting bronchodilators, may be helpful in alleviating 1°C per hour should be sufficient. 7 Because shivering hypoxia when bronchospasm is suspected. increases metabolic oxygen requirements, efforts should be made to avoid producing shivering until circulation SUBMERSION IN ICE WATER can adequately deliver oxygen to the tissue. 16 Although hypothermia is contraindicated as a thera - peutic method, hypothermia during drowning appears to PROGNOSIS be protective. The rapid drop in core body temperature The survival rate after fluid aspiration is inversely pro - decreases the metabolic oxygen requirements of the portional to the volume of water aspirated. 21 A recent brain. 16 A “” has been identified in seals, dogs, review of 15 dogs and one cat that drowned in freshwater and humans, in which the sensation of cold water on the found a mortality rate of 37.5%, with animals in respira - face causes and bradycardia and vasoconstriction tory failure having a worse prognosis. 8 In humans, retro - causes shunting of blood to the heart and brain to con - spective data have been analyzed to identify prognostic serve oxygen. 47 This can allow a hypoxic animal to survive indicators, but no single factor has been found to be com - for longer periods of time with preservation of brain pletely reliable. Factors that have been suggested to have a function. There are reports 48,49 of humans who were found negative influence on survival and brain function include without a and in ventricular fibrillation or cardiac prolonged submersion 7; a delay in starting resuscitation 7; a asystole after ice water submersion for as long as 66 min - blood pH of 7.1 or less 7; fixed, dilated pupils on presenta - utes and survived, and experimental studies in dogs have tion 51 ; and drowning in warm water (temperature >68°F demonstrated successful resuscitation after the dogs [20°C]). 51 Spontaneous respiration 51 and hypothermia appeared clinically dead. 50 These isolated reports were (<91.4°F [33°C]) with a detectable heartbeat on presenta - likely publicized because the person or animal survived. tion 52 have been associated with survival and preservation More often, anoxia or fatal leads to death. 26,50 of neurologic function. Prognostic scoring systems using When a dog is treated for drowning, its body temper - the Glasgow Coma Scale 53 to assess level of consciousness ature should be noted before resuscitation efforts are on arrival to the hospital have been used, but, again, discontinued. The patient should not be pronounced results have not been consistent. clinically dead until it is normothermic and resuscitation Some human patients present conscious and eupneic but efforts have been unsuccessful. Hypothermic patients develop 7,25,52 or ARDS 7,45 within 12 hours. should be handled carefully because the cold, brady - It is recommended that all human patients, even those that

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appear stable, be hospitalized for at least 24 hours for mon - or seizures should be either kept away from water or care - itoring for late neurologic or pulmonary sequelae. 25 A ret - fully observed while swimming. Likewise, blind or debili - rospective study 36 of 41 dogs and cats that were managed tated dogs should be allowed near water only when closely with mechanical ventilation found an overall survival rate supervised. A barrier might be effective in preventing an of 39%; of the animals that were ventilated because of pri - unsupervised dog from entering a swimming pool or other mary pulmonary parenchymal disease, only 20% (four of body of water. Life jackets are also available for dogs. 20) survived. A similar study 54 found that 20% of animals Owner education and training in canine cardiopulmonary with hypoxemic ventilatory failure were weaned from resuscitation might also prevent fatalities. mechanical ventilation and 11% were discharged. The use of PEEP was significantly associated with the development ACKNOWLEDGMENTS 35 of , which negatively affected survival. The authors acknowledge Jerome H. Modell, MD, DSc(Hon), at the University of Florida College of Medicine, Gainesville, for his expert assistance during the prepa - ration of this manuscript. Dr. Modell is also a courtesy professor of large animal PREVENTION clinical sciences at the University of Florida College of Veterinary Medicine. The number of submersion accidents can be decreased by increasing owner awareness of drowning risks. Dogs REFERENCES can drown in swimming pools, oceans, lakes, ponds, toi - 1. Van Beeck EF, Branche CM, Szpilman D, et al. A new definition of drown - lets, bathtubs, and water bowls. A recent study of freshwa - ing: towards documentation and prevention of a global public health prob - lem. Bull World Health Organ 2005;83(11):853-856. ter drowning in small animals found the distribution of 2. Modell JH. The Pathophysiology and Treatment of Drowning and Near-drown - drowning in man-made and natural bodies of water to be ing . Springfield, IL: Charles C. Thomas; 1971. 3. Centers for Disease Control and Prevention, National Center for Injury Pre - approximately equal; swimming pools were the most com - vention and Control: Water-related injuries: fact sheet . Accessed August 2006 mon man-made drowning location. 8 Dogs that are very at http://www.cdc.gov/ncipc/factsheets/drown.htm . young or elderly may not have the strength to swim or to 4. Modell JH, Kuck EJ, Ruiz BC, et al. Effect of intravenous vs. aspirated dis - tilled water on serum electrolytes and blood gas tensions. J Appl Physiol get out of the water. Dogs with disorders such as syncope 1972;32(5):579-584.

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5. Lunetta P, Modell JH, Sajantila A. What is the incidence and significance of drowning in the Dead Sea: a canine model. Isr J Med Sci 1990 ;26:183-187. “dry-lungs” in bodies found in water? Am J Forensic Pathol 2004;25(4):291-301. 30. Orlowski JP. Vomiting as a complication of the Heimlich maneuver. JAMA 6. Cot C. Les asphyxias accidentelles (submersion, electrocution, intoxication, 1987;258(4):512-513. oxycarbonique) etude clinique, therapeutic et preventive. Editions Medicales 31. Farrow CS: Near-drowning in the dog. Vet Radiol Ultrasound 1977;18(1):6-11. N. Maloine , 1931. 32. Vassilev E, McMichael M. An overview of positive pressure ventilation. J Vet 7. Orlowski JP. Drowning, near-drowning, and ice-water submersion. Pediatr Emerg Crit Care 2004;14(1):15-21. Clin North Am 1987;34(1):75-92. 33. Modell JH, Calderwood HW, Ruiz BC, et al. Effects of ventilatory patterns 8. Heffner GG, Rozanski EA, Beal MW, et al . Evaluation of freshwater submer - on arterial oxygenation after near-drowning in sea water. Anesthesiology sion in small animals: 28 cases (1998-2006). JAVMA 2008:232(2):244-248. 1974;40(4):376-385. 9. Modell JH, Gaub M, Moya F, et al. Physiologic effects of near drowning with 34. Ruiz BC, Calderwood HW, Modell JH, et al. Effects of ventilatory patterns chlorinated fresh water, distilled water, and isotonic saline. Anesthesiology on arterial oxygenation after near-drowning with fresh water: a comparative 1966;27(1):33-41. study in dogs. Anesthesiology 1973;52(4):570-576. 10. Modell JH, Moya F, Williams HD, et al. Changes in blood and A- 35. Bergquist RE, Vogelhut MM, Modell JH, et al. Comparison of ventilatory aDO2 during near-drowning. Anesthesiology 1968;29(3):456-465. patterns in the treatment of freshwater near-drowning in dogs. Anesthesiology 11. Orlowski JP, Abulleil MM, Phillips JM. Effects of tonicities of saline 1980;52(2):142-148. on pulmonary injury in drowning. Crit Care Med 1987;15(2):126-130. 36. King LG, Hendricks JC. Use of positive-pressure ventilation in dogs and 12. Giammona ST, Modell JH. Drowning by total immersion: effects on pulmonary surfactant of distilled water, isotonic saline, and sea water. Am J Dis Child 1967;114:612-616. 13. Orlowski JP, Abulleil MM, Phillips JM. The hemodynamic and cardiovascular effects of near- drowning in hypotonic, isotonic, or hypertonic solutions. Ann Emerg Med 1989;18(10):1044-1049. 14. Pearn J. Pathophysiology of drowning. Med J Austr 1985;142:586-588. 15. Modell JH, Moya F. Effects of volume of aspi - rated fluid during chlorinated fresh water drown - ing. Anesthesiology 1966;27(5):662-672. 16. Modell JH. Drowning. N Engl J Med 1993;328(4):253-256. 17. De Boer J, Biewenga TJ, Kuipers HA, et al. The effects of aspirated and swallowed water in drowning: sea-water and fresh-water experiments on rats and dogs. Anesthesiology 1970;32(1):51-59. 18. Austin WH, Stinebaugh BJ, Rand PW, et al. The effects of drowning on acid-base balance. J Maine Med Assoc 1967;58(1):20-23. 19. Rand PW, Lacombe E, Austin WH, et al. The effects of drowning on blood viscosity. J Maine Med Assoc 1967;58(1):23-27. 20. Tabeling BB, Modell JH. Fluid administration increases oxygen delivery during continuous posi - tive pressure ventilation after freshwater near- drowning. Crit Care Med 1983;11(9):693-696. 21. Modell JH, Moya F, Newby EJ, et al. The effects of fluid volume in sea water drowning. Anesthesi - ology 1967;67(1):68-80. 22. Yagil R, Etzion Z, Oren A. The physiology of drowning. Comp Biochem Physiol A 1983;74(2): 189-193. 23. Sutherland KR, Steinberg KP, Maunder RJ, et al. Pulmonary infection during the acute respi - ratory distress syndrome. Am J Respir Crit Care Med 1995; 152: 550-556. 24. Luce JM. Acute lung injury and the acute respi - ratory distress syndrome. Crit Care Med 1998;26(2):369-376. 25. Modell JH, Graves SA, Kuck EJ. Near-drown - ing: correlation of level of consciousness and sur - vival. Can Anesth Soc J 1980;27(3):211-214. 26. Modell JH, Graves SA, Ketover A. Clinical course of 91 consecutive near-drowning victims. Chest 1976;70(2):231-238. 27. Werner JZ, Safar P, Birchner NG, et al. No improvement in pulmonary status by gravity or abdominal thrusts after sea water near drowning in dogs. Anesthesiology 1982;57(3):A81. 28. Fainer DC, Martin CG, Ivy AC. Resuscitation of dogs from fresh water drowning. J Appl Physiol 1951; 3:417-426. 29. Bark H, Porter A, Gueta V, et al. Physiological changes in respiration associated with near

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cats: 41 cases (1990-1992). JAVMA 1994;204(7):1045-1052. c. pulmonary edema 37. Conn AW, Montes JE, Barker GA, et al. Cerebral salvage in near-drowning fol - d. altered production of surfactant lowing neurological classification by triage. Can Anaesth Soc J 1980;27(3):201-209. 38. Conn AW, Barker GA. Fresh water drowning and near-drowning: an update. Can Anaesth Soc J 1984;31(3):S38-S44. 4. On-site resuscitation efforts can consist of all of 39. Bohn DJ, Biggar WD, Smith CR, et al. Influence of hypothermia, barbiturate the following except therapy, and intracranial pressure monitoring on morbidity and mortality after near-drowning. Crit Care Med 1986;14(6):529-534. a. mouth-to-nose resuscitation . 40. Biggar WD, Bohn DJ, Kent G. Neutrophil circulation and release from bone b. external cardiac massage . marrow during hypothermia. Infect Immun 1983;40(2):708-712. c. gravitational positioning . 41. Remick DG, Xioa H. Hypothermia and sepsis. Front Biosci 2006;11:1006-1013. 42. Calderwood HW, Modell JH, Ruiz BC. The ineffectiveness of steroid therapy d. the Heimlich maneuver . for treatment of fresh-water near-drowning. Anesthesiology 1975;43(6): 642-650. 43. Downs JB, Chapman RL, Modell JH, et al. An evaluation of steroid therapy 5. Which is the most important diagnostic test/tool in aspiration pneumonitis. Anesthesiology 1974;40(2):129-135. 44. Wynne JW, Reynolds JC, Hood CI, et al. Steroid therapy for pneumonitis when a drowned animal presents to the hospital? induced in rabbits by aspiration of foodstuff. Anesthesiology 1979;51(1):11-19. a. thoracic radiography 45. Oakes DD, Sherck JP, Maloney JR, et al. Prognosis and management of vic - tims of near-drowning. J Trauma 1982;22(7):544-549. b. arterial blood gas measurement 46. Ji Q, Zhang L, Wang L, et al. Pentoxifylline reduces indirect lung injury of c. tracheal fluid cytology fresh water drowning in canis. Clinica Chimica Acta 2006;365:221-229. d. pulse oximetry 47. Gonzalez-Rothi RJ. Near drowning: consensus and controversies in pul - monary and cerebral resuscitation. Heart Lung 1987;16(5):474-482. 48. Bolte RG, Black PG, Bowers RS, et al. The use of extracorporeal warming in 6. Which is not a purpose of PEEP or CPAP? a child submerged for 66 minutes. JAMA 1988;260(3):377-379. a. to decrease airway resistance 49 Siebke H, Breivik H. Survival after 40 minutes submersion without cerebral sequellae. Lancet 1975;1(7919):1275-1277. b. to increase the functional residual capacity of the lungs 50. Farthmann EH, Davidson IG. Fresh water drowning at lowered body tem - c. to decrease intrapulmonary shunting perature: an experimental study. Am J Surg 1965;109:410-415. d. to increase venous return 51. Frates C. Analysis of predictive factors on the assessment of warm-water near-drowning in children. Am J Dis Child 1981;135:1006-1008. 52. Biggart MJ, Bohn DJ. Effect of hypothermia and cardiac arrest on outcome 7. Which therapy should be used in the treatment of near-drowning accidents in children. J Pediatr 1990;117(2):179-183. of drowned animals ? 53. Dean JM, Kaufman ND. Prognostic indicators in pediatric near-drowning: the Glasgow coma scale. Crit Care Med 1981;9(7):536-539. a. oxygen therapy c. prophylactic antibiotics 54. Drellich S. Principals of mechanical ventilation. Vet Clin North Am b. dehydration d. steroids Small Anim Pract 2002;32(5):1087-1100. 8. ______is not part of the diving reflex . a. Apnea c. Tachycardia ARTICLE #2 CE TEST b. Vasoconstriction d. Bradycardia This article qualifies for 2 contact hours of continuing CE education credit from the Auburn University College 9. Which statement regarding ice-water submer - of Veterinary Medicine. Subscribers may take sion injuries is true? individual CE tests or sign up for our annual a. The heart is susceptible to ventricular fibrillation. CE program . Those who wish to apply this credit to b. Hypothermia increases the brain’s metabolic oxygen fulfill state relicensure requirements should consult their requirements. respective state authorities regarding the applicability c. Hypothermic patients should be pronounced dead if of this program . CE subscribers can take CE tests online a heartbeat is not detected at presentation to the and get real-time scores at CompendiumVet.com . hospital. d. The patient should not be rewarmed because hypothermia should be used as a treatment. 1. Which condition does not result immediately after aspiration of a large volume of freshwater? 10. Which statement regarding prevention of sub - a. hypernatremia c. hypervolemia mersion injuries is false? b. hemoglobinemia d. hyperkalemia a. Dogs with underlying disorders such as seizures or syncope should not be allowed in the water unsuper - 2. Which condition does not contribute to intrapul - vised. monary shunting after aspiration of salt water? b. Drowning can only occur in a large body of water, a. pulmonary edema c. laryngospasm such as a pool, lake, or ocean . b. loss of surfactant d. ARDS c. Geriatric dogs might not have the strength to get out 3. Which condition is not a feature of ARDS? of the water. a. increased susceptibility to infection d. Life jackets can be helpful in preventing fatalities from b. preservation of normal epithelial fluid and ion transport drowning.

COMPENDIUM June 2008