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Impact of age, submersion time and water temperature on outcome in near-drowning
Resuscitation 52 (2002) 247– 254 www.elsevier.com/locate/resuscitation
Impact of age, submersion time and water temperature on outcome in near-drowning P. Suominen a,*, C. Baillie b, R. Korpela a, S. Rautanen c, S. Ranta a, K.T. Olkkola d a
Department of Anaesthesia and Intensi6e Care, Hospital for Children and Adolescents, Helsinki Uni6ersity Central Hospital, Stenba¨ckinkatu 9, FIN-00029 HUS Helsinki, Finland b Department of Paediatric Surgery, The Royal Li6erpool Children’s Hospital NHS Trust, Li6erpool, UK c Department of Anaesthesia, Hospital of Por6oo, Sairaalantie 1 06200 Por6oo, Finland d Department of Anaesthesia and Intensi6e Care, Helsinki Uni6ersity Central Hospital, To¨o¨lo¨ Hospital, Topeliuksenkatu 5, FIN-00029 HUS Helsinki, Finland Received 29 January 2001; received in revised form 31 January 2001; accepted 12 October 2001
Abstract Background: Because children have less subcutaneous fat, and a higher surface area to body weight ratio than adults, it has been suggested that children cool more rapidly during submersion, and therefore have a better outcome following near-drowning incidents. Aim of the study: To study the impact of age, submersion time, water temperature and rectal temperature in the emergency room on outcome in near-drowning. Material and methods: This retrospective study included all near-drowning victims admitted to the intensive care units of Helsinki University Central Hospital after successful cardiopulmonary resuscitation between 1985 and 1997. Results: There were 61 near-drowning victims (age range: 0.5– 60 years, median 29 years). Males were in the majority (40), and 26 were children ( B16 years). The median water temperature was 17 °C (range: 0 – 33 °C). The median submersion time for the 43 survivors (70%) was 10 min (range: 1 – 38 min). Intact survivors and those with mild neurological disability (n=26, 43%) had a median submersion time of 5 min (range: 1 – 21 min). In non-survivors the median submersion time was 16 min (range: 2–75 min). Submersion time was the only independent predictor of survival in linear regression analysis (PB0.01). Patient age, water temperature and rectal temperature in the emergency room were not significant predictors of survival. Conclusions: Although submersion time is usually an estimate, it is the best prognostic factor after a near drowning incident. Children did not have a better outcome than adults. © 2002 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Near drowning; Water temperature; Submersion time; Hypothermia; Near-drowning severity index
1. Introduction Several factors have a potential bearing on outcome in near-drowning. The most important predictor, the duration of submersion, is at best an estimate given in an extremely stressful situation. It has been shown that prolongation of submersion over 5 – 10 min worsens the prognosis considerably [1 – 3]. However, there are occasional reports, mostly concerning small children, who Abbre6iations: EMS, emergency medical systems; ALS, advanced life support; BLS, basic life support; POPC, Paediatric Overall Performance Category Scale; ER, emergency room; PICU, paediatric intensive care unit. * Corresponding author. Tel.: + 358-9-471-73724, fax: + 358-9471-76711. E-mail address: [email protected] (P. Suominen).
have survived up to 66 min of submersion in water temperatures of 5 °C or less [4–6]. Reports of such ‘miracle’ cases in the medical literature, although fascinating, can readily introduce a false optimism because of the limited reporting of the dismal outcome in the majority of prolonged submersion victims. Children are thought to cool more rapidly than adults during submersion because of their relative lack of subcutaneous fat, and their higher surface area to body weight ratio [5,7]. This rapid cooling may protect the brain, allowing for a better outcome. Although hypothermia has been associated with survival after prolonged submersion [4,6,7], a low rectal temperature measured on arrival in the emergency room (ER) is more commonly a sign of poor outcome [1,2]. A low rectal temperature in the ER may not only reflect rapid
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cooling in cold water but also prolonged submersion in warm water, or a protracted field/transportation time. Therefore, the rectal temperature must be considered together with information on the duration of submersion, water temperature, and the time elapsed following submersion [3,7]. Our original study was the first to evaluate the relationship of water temperature on outcome in neardrowned children [3]. It suggested that the duration of submersion was of greater prognostic significance than the water temperature, and that no significant survival benefit could be demonstrated by cold water in neardrowning. The aim of this study was to evaluate the influence of age, submersion time, water temperature, and rectal temperature in the ER, on outcome in all near-drowning victims. This study includes data from 15 patients reported in our previous study [3].
2. Patients and methods The notes of all successfully resuscitated submersion victims who sustained either cardiac arrest (confirmed by EMS personnel), or required bystander CPR at the scene, were analysed retrospectively. Patients were admitted to either the paediatric intensive care unit (PICU) at the Hospital for Children and Adolescents (HCA), or the adult intensive care unit (ICU) at Helsinki University Central Hospital (HUCH). The study period was from January 1, 1985 to December 31, 1997, and full ethical approval was obtained. The Province of Uusimaa has roughly 1 310 000 inhabitants, and is located in the southern Finland on the coast of the Baltic Sea. In addition to coastal neardrowning incidents, victims were also rescued from some of the many small rivers and lakes in the region.
As Baltic seawater contains little sodium chloride (0.02– 0.75%), all submersion accidents in this study can be considered as freshwater submersions. During the study period, a national emergency phone number was in operation, connecting all emergency calls to six regional response centres (Fig. 1). The quality of pre-hospital medical care was variable. In larger cities EMS units were capable of advanced life support (ALS), whereas in rural and sparsely populated areas often only basic life support (BLS) units were available, occasionally supported by health centre physicians acting as a second tier during regular working hours. In Helsinki, a physician staffed pre-hospital emergency care unit was available 24 h a day. Since 1992, local non-physician staffed EMS systems have been supported by a physician-staffed emergency medical helicopter. The maximum ground transportation time within Helsinki was 25 min, and 30 min for helicopter transfers to HUCH. All critically ill paediatric patients in the Province of Uusimaa are transported to the eight-bed PICU at HUCH. Adult submersion victims from the province are admitted either to the ICU of HUCH, or to five regional and city hospitals. To avoid any bias resulting from the quality of pre-hospital care or variations in regional ICU treatment, only submersion victims who received pre-hospital resuscitation from physicianstaffed ALS units, and who were transported directly for definitive ICU/ PICU care at HUCH were studied. Information sources included pre-hospital EMS records, case notes and autopsy files. Demographic data, cause of submersion, EMS event times, pre-hospital procedures, ICU procedures and neurological outcome were all recorded retrospectively. The pre-hospital treatment of patients conformed to the guidelines issued by the American Heart Association in 1992 [8]. Cardiorespiratory arrest was defined as the absence of
Fig. 1. A map of the Province of Uusimaa including the location of six regional alarm centres (closed circles) with their catchment areas, Helsinki University Central Hospital (HUCH; right angle), and bases of physician-staffed emergency care unit (PECU) and physician-staffed helicopter EMS unit (HEMS; squares).
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consciousness, apnoea, and lack of palpable pulses in major arteries. The duration of CPR was recorded only when EMS personnel became involved in resuscitation measures. The method of rewarming of hypothermic submersion victims was based on the decision of the anaesthesiologist in charge. Passive or external rewarming was used for moderately hypothermic patients (\30 °C) with spontaneous respiration and circulation. Cardiopulmonary bypass or intrathoracic lavage was used in patients who were in cardiac arrest. Post-resuscitation management in the ICU was primarily directed by anaesthesiologists. Most patients received intermittent mandatory ventilation or timecycled pressure-limited mechanical ventilatory support. The Fi02 level and positive end-expiratory pressures were set individually to maintain adequate arterial oxygen tension and oxygen saturation. Prophylactic hyperventilation was used quite commonly until the latter years of the study. Venous drainage was promoted by 30° head elevation. Intracerebral pressure (ICP) monitoring was used in some of the paediatric patients. Furosemide and mannitol were used frequently to reduce elevated ICP. The level of monitoring varied according to the patients’ condition. Continuous arterial pressure or non-invasive blood pressure, core- and peripheral-temperature, ECG, pulse oximetry and central venous pressure monitoring were all recorded. In haemodynamically unstable patients dopamine was the initial inotrope used. Serum glucose, electrolytes and arterial blood gases were regularly assessed. Patients were sedated with bolus doses of intravenous morphine, benzodiazepines, or infusions of opioids and propofol. The temperatures of lake, river and sea surface water at the time of the incidents were obtained from the Finnish Environment Agency and the Finnish Institute of Marine Research. The neurological status of survivors was evaluated retrospectively using hospital records and the Paediatric Overall Performance Category Scale (POPC) [9], measured at discharge. The POPC scale classifies the quality of life into six categories: (1) good; (2) mild disability; (3) moderate disability; (4) severe disability; (5) coma/vegetative state; and (6) death. A good outcome was defined as categories 1 and 2 using the POPC classification. All data are given as median and range. Forward stepwise logistic regression analysis was used to evaluate the importance of individual variables on outcome. Survival was the dependent factor, and age, submersion time, water temperature and rectal temperature in the emergency room were the independent factors entered into the model. Further statistical analysis included Mann– Whitney and Kruskal– Wallis
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tests. P-values less than 0.05 were considered statistically significant.
3. Results Sixty-one near-drowning victims were included in the study with males predominating. Ages ranged from 0.5 to 60 years (median: 29 years, Fig. 2). Forty-three percent were children (median age of 4.4 years); 49 (80%) of the incidents took place in natural waterways and 12 (20%) in recreational facilities. Swimming misadventure (23) was the most common cause for submersion, followed by fall (21), suicide (8), car accident and others (5). Most of the submersion incidents (66%) occurred during summer months (June–August). The mean time from call of arrival for the first responding EMS unit was 8.3 min, and 13.4 min for ALS units. Bystander CPR was initiated in 28 submersion victims, of whom 13 had a spontaneous circulation on arrival of the first EMS unit. It is difficult to say how many of the patients, who received only bystander initiated CPR, actually had cardiac arrest. It is likely that the majority were in respiratory arrest. The submersion time of these 13 patients varied from 1 to 8 min (mean 3 min). The mean body temperature was 34.0 °C. Six of the 13 patients were intubated because of apnoea or respiratory compromise and received mechanical ventilatory support in ICU. CPR was attempted by EMS units in 48 patients. The initial cardiac rhythm was asystole in 36 patients, pulseless electrical activity in 8, and ventricular fibrillation in 3. In one patient the initial rhythm was not recorded. Spontaneous circulation was restored at the scene in 42 patients, and 6 hypothermic patients were transported with ongoing CPR (3 of them survived). Fifty-three patients were intubated at the scene, IV access was obtained in 56, and an intraosseus infusion was used in one. Adrenaline was used in 46 patients, atropine in 9, and sodium bicarbonate in 27. Twelve patients required defibrillation. The mean time from the incident to arrival at HUCH was 57 min (range: 25–120 min). Forty-seven of the 61 patients had a rectal temperature under 35 °C in the ER, and in 6 patients it was not reported. The most commonly used rewarming methods were external rewarming (15), passive rewarming (14), gastric lavage (2) and peritoneal dialysis (2). Eight patients (including 3 survivors) who arrived with ongoing CPR or who arrested subsequently in the ER, were rewarmed by cardiopulmonary by pass (6) or intrathoracic lavage (2). All 13 patients who received bystander CPR alone survived. In addition 30 of the 48 patients (63%) in whom CPR was attempted by EMS personnel survived. Of
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Fig. 2. Boxplots describing age (years), water temperature (°C), submersion time (min), and rectal temperature (°C) for surviving and non-surviving patients. Box length is the inter-quartile length with median value shown as a line across the box. Whiskers show highest and lowest values, excluding outliers which are shown as circles.
the 43 survivors, 26 (60%) had a good neurological outcome, 6 (14%) were moderately disabled and 11 (26%) were severely disabled or in a persistent vegetative state. The median water temperature was 17 °C (range: 0 – 33 °C). In surviving patients the median submersion time was 10 min (range: 1–38 min). The median submersion time in those surviving intact or with mild neurological disability was 5 min (range: 1– 21 min), and 14.5 min in those with a bad neurological outcome (range: 5–38 min). In those who died the median submersion time was 16 min (range: 2– 75 min). Submersion times in patients with good neurological outcome were significantly shorter (P = 0.005) than those of patients with poor neurological or fatal outcome. The only patient who died after less than 5 min duration of submersion, had massive aspiration of gastric content and unsatisfactory airway management during CPR. Submersion time was the only independent predictor of survival in logistic regression analysis (P B 0.01, Fig. 2). A clear cut-off value for the submersion time below which survival could be predicted could not be defined.
4. Discussion Although retrospective, this study is unique in two ways. Firstly, most earlier reports of near drowning incidents are either from a paediatric or adult population base, whereas this report draws from both populations. Secondly, the quality of pre-hospital and ICU care was standardised to avoid institutional bias, allowing a true comparison of adult and paediatric data. In this study the duration of submersion was the only independent predictor of survival in logistic regression analysis. The median submersion time for those who died was 16 min, compared to 5 min for those who survived intact or with mild neurological injury. However, there was no clear cut-off value for the duration of submersion below which a satisfactory outcome could confidently be predicted. Children were not shown to have a better outcome than adults. The present study does not accurately reflect the age profile of near-drowning incidents in Finland. The higher proportion of children is explained by the exclusion of patients from adult ICUs other than that of
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HUCH. Drowning is one of the leading causes of accidental death in children in developed countries. However, compared to other aetiologies of paediatric cardiac arrest, survival is much better following resuscitation after near-drowning [1,10]. This may be partly explained by hypothermia. Controlled hypothermia is known to protect the brain and other organs from hypoxia for as long as 75– 110 min due to rediced brain metabolism and oxygen demand. Cerebral hypoxic tolerance is doubled at 30 °C [11]. However, in controlled hypothermia the patient is first cooled down to 18 °C before the heart is stopped [12], compared to the early hypoxic cardiac arrest in near-drowning which occurs before the development of significant hypothermia. However, when patients become hypothermic from immersion in cold water before submersion and cardiac arrest, this may promote intact survival following prolonged resuscitation and rewarming, as illustrated by a recent case report from Norway [13]. There is little information on the rate of cooling in near-drowning. The cooling rate of the body in water is difficult to estimate, because, in addition to surface cooling, victims also swallow and aspirate water. During surface cooling for cardiac surgery in flowing water at 1 °C the nasopharyngeal temperature of a naked anaesthetised 4 kg infant falls by 1 °C every 5 min. The development of hypothermia is delayed by approximately 1 min per degree for each additional kilogram of body weight [12]. Clothing more than two layers thick reduces the cooling rate by about 43% [14]. In adult volunteers the mean rectal temperature was only 35 °C after 90 min immersion in water at 10 °C [15]. Because the external cooling rate in the near-drowning victim therefore would seem too slow to explain survival after long submersion times, other theories have been suggested to explain survival after prolonged submersion. The potential beneficial effect of the diving reflex, characterised by apnoea, generalised peripheral vasoconstriction and bradycardia, has been criticised, both because it remains unproven in human beings, and because it might reduce the cooling rate as a result of vasoconstriction and apnoea [7]. Aspiration of cold water as a mechanism for rapid cooling also seems unlikely [7,16]. The selective brain cooling hypothesis may be one appropriate explanation for survival after prolonged submersion. The critical factor is how quickly the brain cools to a temperature that protects against hypoxia [7]. An experiment by Conn et al. [17] demonstrated that carotid artery temperatures in dogs anaesthetised with thiopentone fell rapidly (approximately 8.0 °C) in the first 2 min of submersion in both fresh and salt water at 4 °C, and relatively slowly during the remaining 8 min of the experiment. In the control group in which dogs had their heads upon the water surface, the carotid artery temperature fell only 0.8 °C over the same pe-
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riod. The rapid reduction of carotid artery temperature can be explained mainly by pulmonary flushing caused by rapid violent respiratory movements following cold water submersion, and by an increase in the proportion of blood directed to the cerebral circulation, due both to hypercapnic cerebral vasodilatation and general vasoconstriction [7]. However, human near drowning physiology does not necessarily correlate with that of the anaesthetised dogs in Conn et al.’s study [17]. After submersion, the human victim will breath-hold for as long as possible and the laryngeal spasm reflex [7] will further delay fluid inhalation and rapid cooling. Therefore, the period of pulmonary flushing caused by rapid violent respiratory movements will be quite short before cardiac arrest. Conn et al.’s study reported only carotid artery temperatures, and not jugular venous temperature (a better estimate of cerebral temperature), which would decrease more slowly. In dogs cooled by cardiopulmonary bypass, carotid artery temperature decreased from 37 to 34 °C in 2 min, compared to 6 min when cerebral temperature was measured at the tympanic membrane [18]. Furthermore, human cold water submersion victims are often fully clothed, unlike the shaved experimental animals used in Conn et al.’s study. Children did not have a better outcome than adults despite the theoretical advantage of a higher surface area to body weight ratio. In Fig. 3 this ratio was calculated from the Finnish growth charts for boys using 50th percentile values for weight and height [19] and the adult ratio was calculated using median values for weight and height of 34–45 years old Finnish males and females [20]. Body surface was then estimated from a standard nomogram [21], and the ratio of body surface area to body weight was calculated. In newborn infants the surface area to body weight ratio is 2.3 times higher than that of a young adult. However, the ratio decreases rapidly in the first year of life (Fig. 3), suggesting that the theoretical protective effect of more rapid cooling in submerged children compared to adults may be overestimated. Case reports of intact survival after long submersion times also include adults [22]. Most of the adults in this study were middle aged making it unlikely that significant ischaemic heart disease would reduce the chances of survival after CPR in the adult population. The main cause of submersion incidents in children was falling, compared to swimming accidents in adults. Therefore, children were often fully clothed, compared to unclothed adults, and were usually submerged after a shorter immersion time. Many adults had consumed alcohol before the incident, which increases vasodilatation causing further heat loss [7]. The importance of aggressive pre-hospital care must be emphasised, because no positive effects on neurological outcome in near-drowning victims have been
Fig. 3. The ratio of body surface area to body weight and age in Finnish boys and adults (34 – 45 years of age; female closed circle, male square).
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shown by various ICU protocols, including induced hypothermia, barbiturate therapy, and intracranial pressure monitoring [23]. The number of intubations performed by physicians at the scene was high (87%), which may partly explain the survival after relatively long submersion times. However, the overall survival rate of 63% (30/48) in patients in whom CPR was attempted by EMS personnel does not include those patients in whom CPR was discontinued at the scene after unsuccessful resuscitation. It is difficult to set any limits for the duration of submersion after which withdrawal of CPR should be considered. However, if the victim has been submersed in warm water (\5 °C) for longer than 25 min there are practically no chances of survival, and the result of resuscitation will be persistent vegetative state or death as shown by this study and that of Quan et al. [1]. If an EMS-system physician is available on scene, major management decisions can be made. It is unnecessary to initiate and continue CPR in all submersion victims without obvious evidence of death (putrefaction, dependent lividity, or rigor mortis) until arrival in the ER, as is suggested in the Guidelines 2000 for CPR [24]. A physician can decide to terminate CPR after unsuccessful resuscitation at the scene in a warm water neardrowning victim based on the duration of submersion. However, where this is in doubt, resuscitation attempts should continue according to nationally agreed EMS protocols. This study is limited by its retrospective nature, and by the relatively small number of patients included, despite the 12-year study period. The limited statistical power of the study make it prone to type II error, with significant differences in survival possibly going undetected.
5. Conclusions Survival, and quality of neurological outcome after near drowning in adults and children is critically dependent on the duration of submersion (anoxic time), which remains the best prognostic factor. Although unproven, it is conceivable that the quality of care delivered by EMS systems and receiving hospitals, bystander CPR and rapid cooling in icy water may also influence survival. Children did not have a better outcome than adults, contrary to statements prevalent in the medical literature.
Acknowledgements This study was supported by the Laerdal Foundation for Acute Medicine and the Yrjo¨ Jansson Foundation. The authors thank the Finnish Environment Agency
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and the Finnish Institute of Marine Research for their assistance in obtaining the temperatures of the submersion water. References [1] Quan L, Wentz KR, Gore EJ, Copass MK. Outcome and predictors of outcome in pediatric submersion victims receiving prehospital care in King County, Washington. Pediatrics 1990;86:586 – 93. [2] Kyriacou DN, Arcinue EL, Peek C, Kraus JF. Effect of immediate resuscitation on children with submersion injury. Pediatrics 1994;94:137 – 42. [3] Suominen P, Korpela R, Silfvast T, Olkkola KT. Does water temperature affect outcome of nearly drowned children? Resuscitation 1997;35:109 – 13. [4] Bolte RG, Black PG, Bowers RS, Thorne JK, Corneli HM. The use of extracorporeal rewarming in a child submerged for 66 minutes. JAMA 1988;260:377 – 9. [5] Orlowski JP. Drowning, near drowning and ice-water drowning. JAMA 1988;260:390 – 1. [6] Kemp AM, Sibert JR. Outcome in children who nearly drown: a British Isles study. BMJ 1991;302:931 – 3. [7] Golden FStC, Tipton NJ, Scott RC. Immersion, near-drowning and drowning. Br J Anaesth 1997;79:214 – 25. [8] American Heart Association; Emergency Cardiac Care Committee and Subcommittees. Guidelines for cardiopulmonary resuscitation and emergency care. JAMA 1992;268:2171 – 302. [9] AHA Medical/Scientific Statement. Recommended guidelines for uniform reporting of pediatric advanced life support: the pediatric Utstein Style. Circulation 1995;7:2006 – 20. [10] Suominen P, Korpela R, Kuisma M, Silfvast T, Olkkola KT. Paediatric cardiac arrest and resuscitation provided by physician staffed emergency care units. Acta Anaestesiol Scand 1997;41:260 – 5. [11] Rahn H, Prakash O, editors. Acid base regulation and body temperature. Dordrecht: Martinus Nijhof, 1985. [12] Ionescu MI, editor. Techniques in extracorporeal circulation. London: Butterworths, 1981. [13] Gilbert M, Busund R, Skagseth A, Nilsen PA, , Solbe JP. Resuscitation from accidental hypotermia of 13.7 °C with circulatory arrest. Lancet 2000;355:375 – 6. [14] Henssge C. Death time estimation in case work. 1. The rectal temperature time of death nomogram. Forensic Sci Int 1988;38:209 – 36. [15] Tipton M, Eglin C, Gennser M, Golden F. Immersion deaths and deterioration in swimming performance in cold water. Lancet 1999;354:626 – 9. [16] Gooden BA. Why some people do not drown; hypothermia versus the diving response. Med J Aust 1992;157:629 – 32. [17] Conn AW, Miyassaka K, Katayama M, Fujita M, Orima H, Baker G, et al. A canine study of cold water drowning in fresh versus salt water. Crit Care Med 1995;23:2029 – 36. [18] Kuboyama K, Safar P, Radovsky A, et al. Delay in cooling negates the beneficial effect of mild hypothermia after cardiac arrest in dogs: a prospective randomised study. Crit Care Med 1993;21:1348 – 58. [19] Sarva R, Perheentupa J, Tolppanen EM. A novel format for a growth chart. Acta Pediatr Scand 1984;73:527 – 9. [20] Eurostat Yearbook 2000. Luxemburg: Office for Official Publications of the European Committees, 2000: 45. [21] Boyd E, West CD. Nomogram for estimation of surface area. In: Behrman RE, Kliegeman RM, Nelson WE, Vaughan VC III, editors. Nelson’s textbook of pediatrics. Philadelphia, PA: WB Saunders, 1992:1827.
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Portuguese Abstract and Keywords Contexto: Uma vez que as crianc¸ as possuem menos gordura subcutaˆ nea e proporcionalmente uma maior superfı´cie corporal por comparac¸ a˜ o aos adultos, tem sido sugerido que arrefecem mais rapidamente em casos de submersa˜ o, daı´ decorrendo um melhor progno´ stico nos casos de quase afogamento. Objecti6o: Avaliar o impacto da idade, tempo de submersa˜ o, temperatura da a´ gua e temperatura rectal no progno´ stico de situac¸ o˜ es de quase afogamento. Material e me´ todos: Estudo retrospectivo que incluiu todas os casos de quase afogamento admitidos nas Unidades de Cuidados Intensivos do Hospital Central Universita´ rio de Helsinquia, apo´ s reanimac¸ a˜ o cardiorespirato´ ria bem sucedida, entre 1985 e 1997. Resultados: Registaram-se neste perı´odo 61 vı´timas de quase afogamento (idades de 0.5 a 60 anos, mediana 29 anos). A maioria era do sexo masculino (40) e 26 eram crianc¸ as ( B 16 anos). A mediana da temperatura da a´ gua era 17 °C (variac¸ a˜ o: 0 a 33 °C). A mediana do tempo de submersa˜ o entre os 43 sobreviventes (70%) foi de 10 minutos (variac¸ a˜ o: 1 a 21 minutos). Nos na˜ o sobreviventes o tempo me´ dio de submersa˜ o foi de 16 minutos (variac¸ a˜ o de 2 a 75 minutos). Numa ana´ lise de regressa˜ o linear, o tempo de submersa˜ o foi a u´ nica varia´ vel independente com valor preditivo da sobreviveˆ ncia. A idade da vı´tima, a temperatura da a´ gua bem como a temperatura rectal avaliada na sala de emergeˆ ncia na˜ o revelou valor preditivo significativo da probabilidade de sobreviveˆ ncia. Concluso˜ es: Embora o tempo de submersa˜ o seja habitualmente calculado por estimativa, constitui o melhor factor de progno´ stico no contexto de quase afogamento. As crianc¸ as na˜ o mostraram um melhor prognostico comparativamente aos adultos. Pala6ras cha6e: Quase afogamento; Temperatura da a´ gua; Tempo de submersa˜ o; Hipotermia; I´ndice de gravidade de quase afogamento
Spanish Abstract and Keywords Antecedentes: los nin˜ os tienen menos grasa subcuta´ nea y tienen una mayor relacio´ n a´ rea de superficie corporal por peso corporal, por lo que se ha sugerido que los nin˜ os se enfrı´an ma´ s ra´ pido durante la inmersio´ n, y por lo tanto, tendrı´an un mejor prono´ stico despue´ s de incidentes de asfixia por inmersio´ n. Objeti6o del estudio: estudiar el impacto de la edad, tiempo de inmersio´ n, temperatura del agua y temperatura rectal en la sala de emergencias, sobre el resultado en la asfixia por inmersio´ n. Material y me´ todo: Este estudio retrospectivo incluyo´ todas las vı´ctimas de asfixia por inmersio´ n, admitidas en unidades de cuidados intensivos del Hospital Central de la Universidad de Helsinski, despue´ s de reanimacio´ n cardiopulmonar exitosa, entre 1985 y 1995. Resultados: Hubo 61 vı´ctimas de asfixia por inmersio´ n (rango de edad: 0.5 – 60 an˜ os, mediana 29). La mayorı´a fueron varones (40), 26 eran nin˜ os ( B16 an˜ os). La mediana de temperatura del agua fue 17 °C (rango 0 – 33 °C). La mediana de tiempo de inmersio´ n para los 43 sobrevivientes (70%) fue 10 minutos (rango 1 –38 min). Los sobrevivientes intactos y aquellos con dan˜ o neurolo´ gico leve (n=26, 43%) tenı´an mediana de tiempo de inmersio´ n de 5 minutos (rango 1 – 21 minutos). Para los que no sobrevivieron, la mediana de tiempo de sumersio´ n fue 16 minutos (rango: 2 –75). El tiempo de inmersio´ n fue el u´ nico predictor de sobrevida independiente en el ana´ lisis de regresio´ n lineal. La edad del paciente, la temperatura del agua y la temperatura rectal en la sala de emergencias, no fueron predictores significativos de sobrevida. Conclusiones: aunque el tiempo de inmersio´ n es generalmente una estimacio´ n, es el mejor factor prono´ stico despue´ s de incidentes de asfixia por inmersio´ n. Los nin˜ os no tuvieron mejor resultado que los adultos. Palabras cla6e: el casi ahogamiento (Asfixia porinmersio´ n); Temperatura del agua; Tiempo de inmersio´ n; Hipotermia; Indice de gravedad de casi ahogamiento.
Impact of age, submersion time and water temperature on outcome in near-drowning P. Suominen a,*, C. Baillie b, R. Korpela a, S. Rautanen c, S. Ranta a, K.T. Olkkola d a
Department of Anaesthesia and Intensi6e Care, Hospital for Children and Adolescents, Helsinki Uni6ersity Central Hospital, Stenba¨ckinkatu 9, FIN-00029 HUS Helsinki, Finland b Department of Paediatric Surgery, The Royal Li6erpool Children’s Hospital NHS Trust, Li6erpool, UK c Department of Anaesthesia, Hospital of Por6oo, Sairaalantie 1 06200 Por6oo, Finland d Department of Anaesthesia and Intensi6e Care, Helsinki Uni6ersity Central Hospital, To¨o¨lo¨ Hospital, Topeliuksenkatu 5, FIN-00029 HUS Helsinki, Finland Received 29 January 2001; received in revised form 31 January 2001; accepted 12 October 2001
Abstract Background: Because children have less subcutaneous fat, and a higher surface area to body weight ratio than adults, it has been suggested that children cool more rapidly during submersion, and therefore have a better outcome following near-drowning incidents. Aim of the study: To study the impact of age, submersion time, water temperature and rectal temperature in the emergency room on outcome in near-drowning. Material and methods: This retrospective study included all near-drowning victims admitted to the intensive care units of Helsinki University Central Hospital after successful cardiopulmonary resuscitation between 1985 and 1997. Results: There were 61 near-drowning victims (age range: 0.5– 60 years, median 29 years). Males were in the majority (40), and 26 were children ( B16 years). The median water temperature was 17 °C (range: 0 – 33 °C). The median submersion time for the 43 survivors (70%) was 10 min (range: 1 – 38 min). Intact survivors and those with mild neurological disability (n=26, 43%) had a median submersion time of 5 min (range: 1 – 21 min). In non-survivors the median submersion time was 16 min (range: 2–75 min). Submersion time was the only independent predictor of survival in linear regression analysis (PB0.01). Patient age, water temperature and rectal temperature in the emergency room were not significant predictors of survival. Conclusions: Although submersion time is usually an estimate, it is the best prognostic factor after a near drowning incident. Children did not have a better outcome than adults. © 2002 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Near drowning; Water temperature; Submersion time; Hypothermia; Near-drowning severity index
1. Introduction Several factors have a potential bearing on outcome in near-drowning. The most important predictor, the duration of submersion, is at best an estimate given in an extremely stressful situation. It has been shown that prolongation of submersion over 5 – 10 min worsens the prognosis considerably [1 – 3]. However, there are occasional reports, mostly concerning small children, who Abbre6iations: EMS, emergency medical systems; ALS, advanced life support; BLS, basic life support; POPC, Paediatric Overall Performance Category Scale; ER, emergency room; PICU, paediatric intensive care unit. * Corresponding author. Tel.: + 358-9-471-73724, fax: + 358-9471-76711. E-mail address: [email protected] (P. Suominen).
have survived up to 66 min of submersion in water temperatures of 5 °C or less [4–6]. Reports of such ‘miracle’ cases in the medical literature, although fascinating, can readily introduce a false optimism because of the limited reporting of the dismal outcome in the majority of prolonged submersion victims. Children are thought to cool more rapidly than adults during submersion because of their relative lack of subcutaneous fat, and their higher surface area to body weight ratio [5,7]. This rapid cooling may protect the brain, allowing for a better outcome. Although hypothermia has been associated with survival after prolonged submersion [4,6,7], a low rectal temperature measured on arrival in the emergency room (ER) is more commonly a sign of poor outcome [1,2]. A low rectal temperature in the ER may not only reflect rapid
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cooling in cold water but also prolonged submersion in warm water, or a protracted field/transportation time. Therefore, the rectal temperature must be considered together with information on the duration of submersion, water temperature, and the time elapsed following submersion [3,7]. Our original study was the first to evaluate the relationship of water temperature on outcome in neardrowned children [3]. It suggested that the duration of submersion was of greater prognostic significance than the water temperature, and that no significant survival benefit could be demonstrated by cold water in neardrowning. The aim of this study was to evaluate the influence of age, submersion time, water temperature, and rectal temperature in the ER, on outcome in all near-drowning victims. This study includes data from 15 patients reported in our previous study [3].
2. Patients and methods The notes of all successfully resuscitated submersion victims who sustained either cardiac arrest (confirmed by EMS personnel), or required bystander CPR at the scene, were analysed retrospectively. Patients were admitted to either the paediatric intensive care unit (PICU) at the Hospital for Children and Adolescents (HCA), or the adult intensive care unit (ICU) at Helsinki University Central Hospital (HUCH). The study period was from January 1, 1985 to December 31, 1997, and full ethical approval was obtained. The Province of Uusimaa has roughly 1 310 000 inhabitants, and is located in the southern Finland on the coast of the Baltic Sea. In addition to coastal neardrowning incidents, victims were also rescued from some of the many small rivers and lakes in the region.
As Baltic seawater contains little sodium chloride (0.02– 0.75%), all submersion accidents in this study can be considered as freshwater submersions. During the study period, a national emergency phone number was in operation, connecting all emergency calls to six regional response centres (Fig. 1). The quality of pre-hospital medical care was variable. In larger cities EMS units were capable of advanced life support (ALS), whereas in rural and sparsely populated areas often only basic life support (BLS) units were available, occasionally supported by health centre physicians acting as a second tier during regular working hours. In Helsinki, a physician staffed pre-hospital emergency care unit was available 24 h a day. Since 1992, local non-physician staffed EMS systems have been supported by a physician-staffed emergency medical helicopter. The maximum ground transportation time within Helsinki was 25 min, and 30 min for helicopter transfers to HUCH. All critically ill paediatric patients in the Province of Uusimaa are transported to the eight-bed PICU at HUCH. Adult submersion victims from the province are admitted either to the ICU of HUCH, or to five regional and city hospitals. To avoid any bias resulting from the quality of pre-hospital care or variations in regional ICU treatment, only submersion victims who received pre-hospital resuscitation from physicianstaffed ALS units, and who were transported directly for definitive ICU/ PICU care at HUCH were studied. Information sources included pre-hospital EMS records, case notes and autopsy files. Demographic data, cause of submersion, EMS event times, pre-hospital procedures, ICU procedures and neurological outcome were all recorded retrospectively. The pre-hospital treatment of patients conformed to the guidelines issued by the American Heart Association in 1992 [8]. Cardiorespiratory arrest was defined as the absence of
Fig. 1. A map of the Province of Uusimaa including the location of six regional alarm centres (closed circles) with their catchment areas, Helsinki University Central Hospital (HUCH; right angle), and bases of physician-staffed emergency care unit (PECU) and physician-staffed helicopter EMS unit (HEMS; squares).
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consciousness, apnoea, and lack of palpable pulses in major arteries. The duration of CPR was recorded only when EMS personnel became involved in resuscitation measures. The method of rewarming of hypothermic submersion victims was based on the decision of the anaesthesiologist in charge. Passive or external rewarming was used for moderately hypothermic patients (\30 °C) with spontaneous respiration and circulation. Cardiopulmonary bypass or intrathoracic lavage was used in patients who were in cardiac arrest. Post-resuscitation management in the ICU was primarily directed by anaesthesiologists. Most patients received intermittent mandatory ventilation or timecycled pressure-limited mechanical ventilatory support. The Fi02 level and positive end-expiratory pressures were set individually to maintain adequate arterial oxygen tension and oxygen saturation. Prophylactic hyperventilation was used quite commonly until the latter years of the study. Venous drainage was promoted by 30° head elevation. Intracerebral pressure (ICP) monitoring was used in some of the paediatric patients. Furosemide and mannitol were used frequently to reduce elevated ICP. The level of monitoring varied according to the patients’ condition. Continuous arterial pressure or non-invasive blood pressure, core- and peripheral-temperature, ECG, pulse oximetry and central venous pressure monitoring were all recorded. In haemodynamically unstable patients dopamine was the initial inotrope used. Serum glucose, electrolytes and arterial blood gases were regularly assessed. Patients were sedated with bolus doses of intravenous morphine, benzodiazepines, or infusions of opioids and propofol. The temperatures of lake, river and sea surface water at the time of the incidents were obtained from the Finnish Environment Agency and the Finnish Institute of Marine Research. The neurological status of survivors was evaluated retrospectively using hospital records and the Paediatric Overall Performance Category Scale (POPC) [9], measured at discharge. The POPC scale classifies the quality of life into six categories: (1) good; (2) mild disability; (3) moderate disability; (4) severe disability; (5) coma/vegetative state; and (6) death. A good outcome was defined as categories 1 and 2 using the POPC classification. All data are given as median and range. Forward stepwise logistic regression analysis was used to evaluate the importance of individual variables on outcome. Survival was the dependent factor, and age, submersion time, water temperature and rectal temperature in the emergency room were the independent factors entered into the model. Further statistical analysis included Mann– Whitney and Kruskal– Wallis
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tests. P-values less than 0.05 were considered statistically significant.
3. Results Sixty-one near-drowning victims were included in the study with males predominating. Ages ranged from 0.5 to 60 years (median: 29 years, Fig. 2). Forty-three percent were children (median age of 4.4 years); 49 (80%) of the incidents took place in natural waterways and 12 (20%) in recreational facilities. Swimming misadventure (23) was the most common cause for submersion, followed by fall (21), suicide (8), car accident and others (5). Most of the submersion incidents (66%) occurred during summer months (June–August). The mean time from call of arrival for the first responding EMS unit was 8.3 min, and 13.4 min for ALS units. Bystander CPR was initiated in 28 submersion victims, of whom 13 had a spontaneous circulation on arrival of the first EMS unit. It is difficult to say how many of the patients, who received only bystander initiated CPR, actually had cardiac arrest. It is likely that the majority were in respiratory arrest. The submersion time of these 13 patients varied from 1 to 8 min (mean 3 min). The mean body temperature was 34.0 °C. Six of the 13 patients were intubated because of apnoea or respiratory compromise and received mechanical ventilatory support in ICU. CPR was attempted by EMS units in 48 patients. The initial cardiac rhythm was asystole in 36 patients, pulseless electrical activity in 8, and ventricular fibrillation in 3. In one patient the initial rhythm was not recorded. Spontaneous circulation was restored at the scene in 42 patients, and 6 hypothermic patients were transported with ongoing CPR (3 of them survived). Fifty-three patients were intubated at the scene, IV access was obtained in 56, and an intraosseus infusion was used in one. Adrenaline was used in 46 patients, atropine in 9, and sodium bicarbonate in 27. Twelve patients required defibrillation. The mean time from the incident to arrival at HUCH was 57 min (range: 25–120 min). Forty-seven of the 61 patients had a rectal temperature under 35 °C in the ER, and in 6 patients it was not reported. The most commonly used rewarming methods were external rewarming (15), passive rewarming (14), gastric lavage (2) and peritoneal dialysis (2). Eight patients (including 3 survivors) who arrived with ongoing CPR or who arrested subsequently in the ER, were rewarmed by cardiopulmonary by pass (6) or intrathoracic lavage (2). All 13 patients who received bystander CPR alone survived. In addition 30 of the 48 patients (63%) in whom CPR was attempted by EMS personnel survived. Of
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Fig. 2. Boxplots describing age (years), water temperature (°C), submersion time (min), and rectal temperature (°C) for surviving and non-surviving patients. Box length is the inter-quartile length with median value shown as a line across the box. Whiskers show highest and lowest values, excluding outliers which are shown as circles.
the 43 survivors, 26 (60%) had a good neurological outcome, 6 (14%) were moderately disabled and 11 (26%) were severely disabled or in a persistent vegetative state. The median water temperature was 17 °C (range: 0 – 33 °C). In surviving patients the median submersion time was 10 min (range: 1–38 min). The median submersion time in those surviving intact or with mild neurological disability was 5 min (range: 1– 21 min), and 14.5 min in those with a bad neurological outcome (range: 5–38 min). In those who died the median submersion time was 16 min (range: 2– 75 min). Submersion times in patients with good neurological outcome were significantly shorter (P = 0.005) than those of patients with poor neurological or fatal outcome. The only patient who died after less than 5 min duration of submersion, had massive aspiration of gastric content and unsatisfactory airway management during CPR. Submersion time was the only independent predictor of survival in logistic regression analysis (P B 0.01, Fig. 2). A clear cut-off value for the submersion time below which survival could be predicted could not be defined.
4. Discussion Although retrospective, this study is unique in two ways. Firstly, most earlier reports of near drowning incidents are either from a paediatric or adult population base, whereas this report draws from both populations. Secondly, the quality of pre-hospital and ICU care was standardised to avoid institutional bias, allowing a true comparison of adult and paediatric data. In this study the duration of submersion was the only independent predictor of survival in logistic regression analysis. The median submersion time for those who died was 16 min, compared to 5 min for those who survived intact or with mild neurological injury. However, there was no clear cut-off value for the duration of submersion below which a satisfactory outcome could confidently be predicted. Children were not shown to have a better outcome than adults. The present study does not accurately reflect the age profile of near-drowning incidents in Finland. The higher proportion of children is explained by the exclusion of patients from adult ICUs other than that of
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HUCH. Drowning is one of the leading causes of accidental death in children in developed countries. However, compared to other aetiologies of paediatric cardiac arrest, survival is much better following resuscitation after near-drowning [1,10]. This may be partly explained by hypothermia. Controlled hypothermia is known to protect the brain and other organs from hypoxia for as long as 75– 110 min due to rediced brain metabolism and oxygen demand. Cerebral hypoxic tolerance is doubled at 30 °C [11]. However, in controlled hypothermia the patient is first cooled down to 18 °C before the heart is stopped [12], compared to the early hypoxic cardiac arrest in near-drowning which occurs before the development of significant hypothermia. However, when patients become hypothermic from immersion in cold water before submersion and cardiac arrest, this may promote intact survival following prolonged resuscitation and rewarming, as illustrated by a recent case report from Norway [13]. There is little information on the rate of cooling in near-drowning. The cooling rate of the body in water is difficult to estimate, because, in addition to surface cooling, victims also swallow and aspirate water. During surface cooling for cardiac surgery in flowing water at 1 °C the nasopharyngeal temperature of a naked anaesthetised 4 kg infant falls by 1 °C every 5 min. The development of hypothermia is delayed by approximately 1 min per degree for each additional kilogram of body weight [12]. Clothing more than two layers thick reduces the cooling rate by about 43% [14]. In adult volunteers the mean rectal temperature was only 35 °C after 90 min immersion in water at 10 °C [15]. Because the external cooling rate in the near-drowning victim therefore would seem too slow to explain survival after long submersion times, other theories have been suggested to explain survival after prolonged submersion. The potential beneficial effect of the diving reflex, characterised by apnoea, generalised peripheral vasoconstriction and bradycardia, has been criticised, both because it remains unproven in human beings, and because it might reduce the cooling rate as a result of vasoconstriction and apnoea [7]. Aspiration of cold water as a mechanism for rapid cooling also seems unlikely [7,16]. The selective brain cooling hypothesis may be one appropriate explanation for survival after prolonged submersion. The critical factor is how quickly the brain cools to a temperature that protects against hypoxia [7]. An experiment by Conn et al. [17] demonstrated that carotid artery temperatures in dogs anaesthetised with thiopentone fell rapidly (approximately 8.0 °C) in the first 2 min of submersion in both fresh and salt water at 4 °C, and relatively slowly during the remaining 8 min of the experiment. In the control group in which dogs had their heads upon the water surface, the carotid artery temperature fell only 0.8 °C over the same pe-
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riod. The rapid reduction of carotid artery temperature can be explained mainly by pulmonary flushing caused by rapid violent respiratory movements following cold water submersion, and by an increase in the proportion of blood directed to the cerebral circulation, due both to hypercapnic cerebral vasodilatation and general vasoconstriction [7]. However, human near drowning physiology does not necessarily correlate with that of the anaesthetised dogs in Conn et al.’s study [17]. After submersion, the human victim will breath-hold for as long as possible and the laryngeal spasm reflex [7] will further delay fluid inhalation and rapid cooling. Therefore, the period of pulmonary flushing caused by rapid violent respiratory movements will be quite short before cardiac arrest. Conn et al.’s study reported only carotid artery temperatures, and not jugular venous temperature (a better estimate of cerebral temperature), which would decrease more slowly. In dogs cooled by cardiopulmonary bypass, carotid artery temperature decreased from 37 to 34 °C in 2 min, compared to 6 min when cerebral temperature was measured at the tympanic membrane [18]. Furthermore, human cold water submersion victims are often fully clothed, unlike the shaved experimental animals used in Conn et al.’s study. Children did not have a better outcome than adults despite the theoretical advantage of a higher surface area to body weight ratio. In Fig. 3 this ratio was calculated from the Finnish growth charts for boys using 50th percentile values for weight and height [19] and the adult ratio was calculated using median values for weight and height of 34–45 years old Finnish males and females [20]. Body surface was then estimated from a standard nomogram [21], and the ratio of body surface area to body weight was calculated. In newborn infants the surface area to body weight ratio is 2.3 times higher than that of a young adult. However, the ratio decreases rapidly in the first year of life (Fig. 3), suggesting that the theoretical protective effect of more rapid cooling in submerged children compared to adults may be overestimated. Case reports of intact survival after long submersion times also include adults [22]. Most of the adults in this study were middle aged making it unlikely that significant ischaemic heart disease would reduce the chances of survival after CPR in the adult population. The main cause of submersion incidents in children was falling, compared to swimming accidents in adults. Therefore, children were often fully clothed, compared to unclothed adults, and were usually submerged after a shorter immersion time. Many adults had consumed alcohol before the incident, which increases vasodilatation causing further heat loss [7]. The importance of aggressive pre-hospital care must be emphasised, because no positive effects on neurological outcome in near-drowning victims have been
Fig. 3. The ratio of body surface area to body weight and age in Finnish boys and adults (34 – 45 years of age; female closed circle, male square).
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shown by various ICU protocols, including induced hypothermia, barbiturate therapy, and intracranial pressure monitoring [23]. The number of intubations performed by physicians at the scene was high (87%), which may partly explain the survival after relatively long submersion times. However, the overall survival rate of 63% (30/48) in patients in whom CPR was attempted by EMS personnel does not include those patients in whom CPR was discontinued at the scene after unsuccessful resuscitation. It is difficult to set any limits for the duration of submersion after which withdrawal of CPR should be considered. However, if the victim has been submersed in warm water (\5 °C) for longer than 25 min there are practically no chances of survival, and the result of resuscitation will be persistent vegetative state or death as shown by this study and that of Quan et al. [1]. If an EMS-system physician is available on scene, major management decisions can be made. It is unnecessary to initiate and continue CPR in all submersion victims without obvious evidence of death (putrefaction, dependent lividity, or rigor mortis) until arrival in the ER, as is suggested in the Guidelines 2000 for CPR [24]. A physician can decide to terminate CPR after unsuccessful resuscitation at the scene in a warm water neardrowning victim based on the duration of submersion. However, where this is in doubt, resuscitation attempts should continue according to nationally agreed EMS protocols. This study is limited by its retrospective nature, and by the relatively small number of patients included, despite the 12-year study period. The limited statistical power of the study make it prone to type II error, with significant differences in survival possibly going undetected.
5. Conclusions Survival, and quality of neurological outcome after near drowning in adults and children is critically dependent on the duration of submersion (anoxic time), which remains the best prognostic factor. Although unproven, it is conceivable that the quality of care delivered by EMS systems and receiving hospitals, bystander CPR and rapid cooling in icy water may also influence survival. Children did not have a better outcome than adults, contrary to statements prevalent in the medical literature.
Acknowledgements This study was supported by the Laerdal Foundation for Acute Medicine and the Yrjo¨ Jansson Foundation. The authors thank the Finnish Environment Agency
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and the Finnish Institute of Marine Research for their assistance in obtaining the temperatures of the submersion water. References [1] Quan L, Wentz KR, Gore EJ, Copass MK. Outcome and predictors of outcome in pediatric submersion victims receiving prehospital care in King County, Washington. Pediatrics 1990;86:586 – 93. [2] Kyriacou DN, Arcinue EL, Peek C, Kraus JF. Effect of immediate resuscitation on children with submersion injury. Pediatrics 1994;94:137 – 42. [3] Suominen P, Korpela R, Silfvast T, Olkkola KT. Does water temperature affect outcome of nearly drowned children? Resuscitation 1997;35:109 – 13. [4] Bolte RG, Black PG, Bowers RS, Thorne JK, Corneli HM. The use of extracorporeal rewarming in a child submerged for 66 minutes. JAMA 1988;260:377 – 9. [5] Orlowski JP. Drowning, near drowning and ice-water drowning. JAMA 1988;260:390 – 1. [6] Kemp AM, Sibert JR. Outcome in children who nearly drown: a British Isles study. BMJ 1991;302:931 – 3. [7] Golden FStC, Tipton NJ, Scott RC. Immersion, near-drowning and drowning. Br J Anaesth 1997;79:214 – 25. [8] American Heart Association; Emergency Cardiac Care Committee and Subcommittees. Guidelines for cardiopulmonary resuscitation and emergency care. JAMA 1992;268:2171 – 302. [9] AHA Medical/Scientific Statement. Recommended guidelines for uniform reporting of pediatric advanced life support: the pediatric Utstein Style. Circulation 1995;7:2006 – 20. [10] Suominen P, Korpela R, Kuisma M, Silfvast T, Olkkola KT. Paediatric cardiac arrest and resuscitation provided by physician staffed emergency care units. Acta Anaestesiol Scand 1997;41:260 – 5. [11] Rahn H, Prakash O, editors. Acid base regulation and body temperature. Dordrecht: Martinus Nijhof, 1985. [12] Ionescu MI, editor. Techniques in extracorporeal circulation. London: Butterworths, 1981. [13] Gilbert M, Busund R, Skagseth A, Nilsen PA, , Solbe JP. Resuscitation from accidental hypotermia of 13.7 °C with circulatory arrest. Lancet 2000;355:375 – 6. [14] Henssge C. Death time estimation in case work. 1. The rectal temperature time of death nomogram. Forensic Sci Int 1988;38:209 – 36. [15] Tipton M, Eglin C, Gennser M, Golden F. Immersion deaths and deterioration in swimming performance in cold water. Lancet 1999;354:626 – 9. [16] Gooden BA. Why some people do not drown; hypothermia versus the diving response. Med J Aust 1992;157:629 – 32. [17] Conn AW, Miyassaka K, Katayama M, Fujita M, Orima H, Baker G, et al. A canine study of cold water drowning in fresh versus salt water. Crit Care Med 1995;23:2029 – 36. [18] Kuboyama K, Safar P, Radovsky A, et al. Delay in cooling negates the beneficial effect of mild hypothermia after cardiac arrest in dogs: a prospective randomised study. Crit Care Med 1993;21:1348 – 58. [19] Sarva R, Perheentupa J, Tolppanen EM. A novel format for a growth chart. Acta Pediatr Scand 1984;73:527 – 9. [20] Eurostat Yearbook 2000. Luxemburg: Office for Official Publications of the European Committees, 2000: 45. [21] Boyd E, West CD. Nomogram for estimation of surface area. In: Behrman RE, Kliegeman RM, Nelson WE, Vaughan VC III, editors. Nelson’s textbook of pediatrics. Philadelphia, PA: WB Saunders, 1992:1827.
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Portuguese Abstract and Keywords Contexto: Uma vez que as crianc¸ as possuem menos gordura subcutaˆ nea e proporcionalmente uma maior superfı´cie corporal por comparac¸ a˜ o aos adultos, tem sido sugerido que arrefecem mais rapidamente em casos de submersa˜ o, daı´ decorrendo um melhor progno´ stico nos casos de quase afogamento. Objecti6o: Avaliar o impacto da idade, tempo de submersa˜ o, temperatura da a´ gua e temperatura rectal no progno´ stico de situac¸ o˜ es de quase afogamento. Material e me´ todos: Estudo retrospectivo que incluiu todas os casos de quase afogamento admitidos nas Unidades de Cuidados Intensivos do Hospital Central Universita´ rio de Helsinquia, apo´ s reanimac¸ a˜ o cardiorespirato´ ria bem sucedida, entre 1985 e 1997. Resultados: Registaram-se neste perı´odo 61 vı´timas de quase afogamento (idades de 0.5 a 60 anos, mediana 29 anos). A maioria era do sexo masculino (40) e 26 eram crianc¸ as ( B 16 anos). A mediana da temperatura da a´ gua era 17 °C (variac¸ a˜ o: 0 a 33 °C). A mediana do tempo de submersa˜ o entre os 43 sobreviventes (70%) foi de 10 minutos (variac¸ a˜ o: 1 a 21 minutos). Nos na˜ o sobreviventes o tempo me´ dio de submersa˜ o foi de 16 minutos (variac¸ a˜ o de 2 a 75 minutos). Numa ana´ lise de regressa˜ o linear, o tempo de submersa˜ o foi a u´ nica varia´ vel independente com valor preditivo da sobreviveˆ ncia. A idade da vı´tima, a temperatura da a´ gua bem como a temperatura rectal avaliada na sala de emergeˆ ncia na˜ o revelou valor preditivo significativo da probabilidade de sobreviveˆ ncia. Concluso˜ es: Embora o tempo de submersa˜ o seja habitualmente calculado por estimativa, constitui o melhor factor de progno´ stico no contexto de quase afogamento. As crianc¸ as na˜ o mostraram um melhor prognostico comparativamente aos adultos. Pala6ras cha6e: Quase afogamento; Temperatura da a´ gua; Tempo de submersa˜ o; Hipotermia; I´ndice de gravidade de quase afogamento
Spanish Abstract and Keywords Antecedentes: los nin˜ os tienen menos grasa subcuta´ nea y tienen una mayor relacio´ n a´ rea de superficie corporal por peso corporal, por lo que se ha sugerido que los nin˜ os se enfrı´an ma´ s ra´ pido durante la inmersio´ n, y por lo tanto, tendrı´an un mejor prono´ stico despue´ s de incidentes de asfixia por inmersio´ n. Objeti6o del estudio: estudiar el impacto de la edad, tiempo de inmersio´ n, temperatura del agua y temperatura rectal en la sala de emergencias, sobre el resultado en la asfixia por inmersio´ n. Material y me´ todo: Este estudio retrospectivo incluyo´ todas las vı´ctimas de asfixia por inmersio´ n, admitidas en unidades de cuidados intensivos del Hospital Central de la Universidad de Helsinski, despue´ s de reanimacio´ n cardiopulmonar exitosa, entre 1985 y 1995. Resultados: Hubo 61 vı´ctimas de asfixia por inmersio´ n (rango de edad: 0.5 – 60 an˜ os, mediana 29). La mayorı´a fueron varones (40), 26 eran nin˜ os ( B16 an˜ os). La mediana de temperatura del agua fue 17 °C (rango 0 – 33 °C). La mediana de tiempo de inmersio´ n para los 43 sobrevivientes (70%) fue 10 minutos (rango 1 –38 min). Los sobrevivientes intactos y aquellos con dan˜ o neurolo´ gico leve (n=26, 43%) tenı´an mediana de tiempo de inmersio´ n de 5 minutos (rango 1 – 21 minutos). Para los que no sobrevivieron, la mediana de tiempo de sumersio´ n fue 16 minutos (rango: 2 –75). El tiempo de inmersio´ n fue el u´ nico predictor de sobrevida independiente en el ana´ lisis de regresio´ n lineal. La edad del paciente, la temperatura del agua y la temperatura rectal en la sala de emergencias, no fueron predictores significativos de sobrevida. Conclusiones: aunque el tiempo de inmersio´ n es generalmente una estimacio´ n, es el mejor factor prono´ stico despue´ s de incidentes de asfixia por inmersio´ n. Los nin˜ os no tuvieron mejor resultado que los adultos. Palabras cla6e: el casi ahogamiento (Asfixia porinmersio´ n); Temperatura del agua; Tiempo de inmersio´ n; Hipotermia; Indice de gravedad de casi ahogamiento.