RESUMO
BACKGROUND: Appropriate dispatch criteria and helicopter emergency medical service (HEMS) crew decisions are crucial for avoiding over-triage and reducing the number of concurrencies. The aim of the present study was to compare patient outcomes after completed HEMS missions and missions cancelled by the HEMS due to concurrencies. METHODS: Missions cancelled due to concurrencies (AMB group) and completed HEMS missions (HEMS group) in Western Norway from 2004 to 2013 were assessed. Outcomes were survival to hospital discharge, physiology score in the emergency department, emergency interventions in the hospital, type of department for patient admittance, and length of hospital stay. RESULTS: Survival to discharge was similar in the two groups. One-third of the primary missions in the HEMS group and 13% in the AMB group were patients with pre-hospital conditions posing an acute threat to life. In a sub group analysis of these patients, HEMS patients were younger, more often admitted to an intensive care unit, and had an increased survival to discharge. In addition, the HEMS group had a greater proportion of patients with deranged physiology in the emergency department according to an early warning score. CONCLUSION: Patients in the HEMS group seemed to be critically ill more often and received more emergency interventions, but the two groups had similar in-hospital mortality. Patients with pre-hospital signs of acute threat to life were younger and presented increased survival in the HEMS group.
Assuntos
Resgate Aéreo , Adulto , Idoso , Serviço Hospitalar de Emergência , Feminino , Mortalidade Hospitalar , Humanos , Masculino , Pessoa de Meia-Idade , Estudos RetrospectivosRESUMO
BACKGROUND: The Helicopter Emergency Medical Service (HEMS) in Norway is operated day and night, despite challenging geography and weather. In Western Norway, three ambulance helicopters, with a rapid response car as an alternative, cover close to 1 million inhabitants in an area of 45,000 km(2) . Our objective was to assess patterns of emergency medical problems and treatments in HEMS in a geographically large, but sparsely populated region. METHODS: Data from all HEMS dispatches during 2004-2013 were assessed retrospectively. Information was analyzed with respect to patient treatment and characteristics, in addition to variations in services use during the day, week, and seasons. RESULTS: A total of 42,456 dispatches were analyzed. One third of the patients encountered were severely ill or injured, and two thirds of these received advanced treatment. Median activation time and on-scene time in primary helicopter missions were 5 and 11 min, respectively. Most patients (95%) were reached within 45 min by helicopter or rapid response car. Patterns of use did not change. More than one third of all dispatches were declined or aborted, mostly due to no longer medical indication, bad weather conditions, or competing missions. CONCLUSION: One third of the patients encountered were severely ill or injured, and more than two thirds of these received advanced treatment. HEMS use did not change over the 10-year period, however HEMS use peaked during daytime, weekends, and the summer. More than one third of all dispatches were declined or aborted.
Assuntos
Resgate Aéreo/estatística & dados numéricos , Serviços Médicos de Emergência/estatística & dados numéricos , Adolescente , Adulto , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Pessoa de Meia-Idade , Noruega/epidemiologia , Pacientes , Estudos Retrospectivos , Estações do Ano , Tempo para o Tratamento , Ferimentos e Lesões/epidemiologia , Ferimentos e Lesões/terapia , Adulto JovemRESUMO
BACKGROUND: Reported incidence and survival from in-hospital and out-of-hospital cardiac arrest show great variability, making it difficult to compare the groups. In order to eliminate effects of time and culture, we investigated out-of-hospital cardiac arrest compared with in-hospital cardiac arrest in our community over a 1-year period. METHODS: We conducted a cohort study including patients with in-hospital and out-of-hospital cardiac arrest. Multiple data sources were screened in order to identify all cardiac arrest patients. Utstein style data were collected prospectively from 1 December 2008 to 30 November 2009 with subsequent analysis. RESULTS: A total of 380 resuscitations because of cardiac arrest were included, 154 (40.6%) in-hospital and 226 (59.4%) out-of-hospital. The in-hospital cardiac arrest group was older, had higher proportions of witnessed cardiac arrest, bystander cardiopulmonary resuscitation, bystander direct current (DC) shock and professional first rescuer. Survival to hospital discharge was 16.2% for in-hospital cardiac arrest vs. 16.8% for out-of-hospital cardiac arrest. CONCLUSION: Survival from in-hospital and out-of-hospital cardiac arrest in this cohort is similar.
Assuntos
Parada Cardíaca/mortalidade , Parada Cardíaca Extra-Hospitalar/mortalidade , Fatores Etários , Idoso , Reanimação Cardiopulmonar , Estudos de Coortes , Serviços Médicos de Emergência , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Noruega/epidemiologia , Equipe de Assistência ao Paciente , Estudos Prospectivos , Fatores Sexuais , Análise de Sobrevida , Resultado do TratamentoRESUMO
INTRODUCTION: Therapeutic hypothermia (TH) after out-of-hospital cardiac arrest (OHCA) was adopted early in Norway. Since 2004 the general recommendation has been to cool all unconscious OHCA patients treated in the intensive care unit (ICU), but the decision to cool individual patients was left to the responsible physician. We assessed factors that were associated with use of TH and predicted survival. METHOD: We conducted a retrospective observational study of prospectively collected cardiac arrest and ICU registry data from 2004 to 2008 at three university hospitals. RESULTS: A total of 715 unconscious patients older than 18 years of age, who suffered OHCA of both cardiac and non-cardiac causes, were included. With an overall TH use of 70%, the survival to discharge was 42%, with 90% of the survivors having a favourable cerebral outcome. Known positive prognostic factors such as witnessed arrest, bystander cardio pulmonary resuscitation (CPR), shockable rhythm and cardiac origin were all positive predictors of TH use and survival. On the other side, increasing age predicted a lower utilisation of TH: Odds Ratio (OR), 0.96 (95% CI, 0.94 to 0.97); as well as a lower survival: OR 0.96 (95% CI, 0.94 to 0.97). Female gender was also associated with a lower use of TH: OR 0.65 (95% CI, 0.43 to 0.97); and a poorer survival: OR 0.57 (95% CI, 0.36 to 0.92). After correcting for other prognostic factors, use of TH remained an independent predictor of improved survival with OR 1.91 (95% CI 1.18-3.06; P <0.001). Analysing subgroups divided after initial rhythm, these effects remained unchanged for patients with shockable rhythm, but not for patients with non-shockable rhythm where use of TH and female gender lost their predictive value. CONCLUSIONS: Although TH was used in the majority of unconscious OHCA patients admitted to the ICU, actual use varied significantly between subgroups. Increasing age predicted both a decreased utilisation of TH as well as lower survival. Further, in patients with a shockable rhythm female gender predicted both a lower use of TH and poorer survival. Our results indicate an underutilisation of TH in some subgroups. Hence, more research on factors affecting TH use and the associated outcomes in subgroups of post-resuscitation patients is needed.
Assuntos
Hipotermia Induzida/métodos , Unidades de Terapia Intensiva , Parada Cardíaca Extra-Hospitalar/mortalidade , Parada Cardíaca Extra-Hospitalar/terapia , Admissão do Paciente , Inconsciente Psicológico , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Hipotermia Induzida/tendências , Unidades de Terapia Intensiva/tendências , Masculino , Pessoa de Meia-Idade , Parada Cardíaca Extra-Hospitalar/diagnóstico , Admissão do Paciente/tendências , Valor Preditivo dos Testes , Estudos Prospectivos , Sistema de Registros , Estudos Retrospectivos , Taxa de Sobrevida/tendências , Resultado do TratamentoRESUMO
BACKGROUND: A substantial proportion of anaesthesia-related adverse events are preventable by identification and correction of errors in planning, communication, fatigue, stress, and equipment. The aim of this study was to develop and implement a pre-induction checklist in order to identify and solve problems before induction of anaesthesia. METHODS: The checklist was developed in a stepwise manner using a modified Delphi technique, literature search, expert's opinion, and a pilot version, and then implemented in a clinical environment during a 13-week study period. Each list was registered and analysed using statistical process control. The checklist was mandatory, but emergency cases were excluded. RESULTS: The checklist, containing 26 items, was used in 502 (61%) of a total of 829 inductions. Eighty-five checklists (17%) identified one or more missing items. The number of missing items decreased significantly throughout the study period. The most important missing items were lack of a second laryngoscope available, introducer not having been fitted to the endotracheal tube, the endotracheal tube cuff not having been tested, and no separate ventilation bag being available. It took a median of 88.5 s (range 52-118) to perform the checklist when no items were missing. The pre-induction time was the same before and after the checklist was introduced (25.1 vs. 24.3 min, P50.25). CONCLUSIONS: It is possible to develop, introduce, and use a pre-induction checklist even in a hectic and stressful clinical environment. The checklist identified and reduced a surprisingly large number of missing items required in a standard induction protocol.
Assuntos
Anestesia/efeitos adversos , Lista de Checagem , Erros Médicos/prevenção & controle , Serviço Hospitalar de Anestesia/organização & administração , Técnica Delphi , Hospitais de Ensino , Humanos , Unidades de Terapia Intensiva/organização & administração , Intubação Intratraqueal/instrumentação , Laringoscópios/provisão & distribuição , Ventiladores Mecânicos/provisão & distribuiçãoRESUMO
BACKGROUND: It is widely believed that placing a patient who has been subjected to suspension trauma in a horizontal position after rescue may cause rescue death. The discussion whether position is important has been dominated by non-medical personnel. Subsequently, this has led to a general advice on emergency treatment of these patients, which may cause incorrect or even fatal treatment. METHODS: To determine whether there is any medical evidence supporting that horizontal positioning after suspension trauma may cause rescue death, the authors located publications, reports, expert opinions and other sources of information addressing the acute treatment of suspension trauma. These sources were then evaluated. RESULTS: Several thousand hits regarding suspension trauma were located on the internet and five articles on the PubMed. Although most of them warned of the dangers of rescue death brought about by assuming the horizontal position after prolonged suspension, the authors found no clinical studies, and none of the sources offered any conclusive evidence as to whether the horizontal position increases the risk of rescue death. Neither the authors, nor the suspension trauma experts who were contacted, had ever experienced or heard of case reports supporting the causal relation between the horizontal position and rescue death. CONCLUSIONS: After evaluating the current literature, the authors found no support for the view that the horizontal position may be potentially fatal for patients exposed to suspension trauma. In the absence of any evidence to the contrary, the authors suggest that the initial management of patients who have had suspension trauma should follow normal guidelines for the acute care of traumatised patients, without special modifications.
Assuntos
Hipotensão Ortostática/terapia , Emergências , Medicina Baseada em Evidências , Humanos , Hipotensão Ortostática/fisiopatologia , Postura , Fatores de RiscoRESUMO
BACKGROUND: Pre-hospital advanced airway management with oxygenation and ventilation may be vital for managing critically ill or injured patients. To improve pre-hospital critical care and develop evidence-based guidelines, research on standardised high-quality data is important. We aimed to identify which airway data were most important to report today and to revise and update a previously reported Utstein-style airway management dataset. METHODS: We recruited sixteen international experts in pre-hospital airway management from Australia, United States of America, and Europe. We used a five-step modified nominal group technique to revise the dataset, and clinical study results from the original template were used to guide the process. RESULTS: The experts agreed on a key dataset of thirty-two operational variables with six additional system variables, organised in time, patient, airway management and system sections. Of the original variables, one remained unchanged, while nineteen were modified in name, category, definition or value. Sixteen new variables were added. The updated dataset covers risk factors for difficult intubation, checklist and standard operating procedure use, pre-oxygenation strategies, the use of drugs in airway management, airway currency training, developments in airway devices, airway management strategies, and patient safety issues not previously described. CONCLUSIONS: Using a modified nominal group technique with international airway management experts, we have updated the Utstein-style dataset to report standardised data from pre-hospital advanced airway management. The dataset enables future airway management research to produce comparable high-quality data across emergency medical systems. We believe this approach will promote research and improve treatment strategies and outcomes for patients receiving pre-hospital advanced airway management. TRIAL REGISTRATION: The Regional Committee for Medical and Health Research Ethics in Western Norway exempted this study from ethical review (Reference: REK-Vest/2017/260).
Assuntos
Manuseio das Vias Aéreas/métodos , Serviços Médicos de Emergência , Intubação Intratraqueal , Projetos de Pesquisa/normas , Adolescente , Adulto , Austrália , Criança , Pré-Escolar , Serviços Médicos de Emergência/métodos , Europa (Continente) , Feminino , Hospitais , Humanos , Lactente , Masculino , Noruega , Adulto JovemRESUMO
OBJECTIVE: Hypothermic cardiopulmonary bypass is associated with capillary fluid leakage, resulting in edema and occasionally organ dysfunction. Systemic inflammatory activation is considered responsible. In some studies methylprednisolone has reduced the weight gain during cardiopulmonary bypass. Vitamin C and alpha-trinositol have been demonstrated to reduce the microvascular fluid and protein leakage in thermal injuries. We therefore tested these three agents for the reduction of cold-induced fluid extravasation during cardiopulmonary bypass. METHODS: A total of 28 piglets were randomly assigned to four groups of 7 each: control group, high-dose vitamin C group, methylprednisolone group, and alpha-trinositol-group. After 1 hour of normothermic cardiopulmonary bypass, hypothermic cardiopulmonary bypass was initiated in all animals and continued to 90 minutes. The fluid level in the extracorporeal circuit reservoir was kept constant at the 400-mL level and used as a fluid gauge. Fluid needs, plasma volume, changes in colloid osmotic pressure in plasma and interstitial fluid, hematocrit, and total water contents in different tissues were recorded, and the protein masses and the fluid extravasation rate were calculated. RESULTS: Hemodilution was about 25% after start of normothermic cardiopulmonary bypass. Cooling did not cause any further changes in hemodilution. During steady-state normothermic cardiopulmonary bypass, the fluid need in all groups was about 0.10 mL/(kg.min), with a 9-fold increase during the first 30 minutes of cooling (P <.001). This increased fluid need was due mainly to increased fluid extravasation from the intravascular to the interstitial space at a mean rate of 0.6 mL/(kg.min) (range 0.5-0.7 mL/[kg.min]; P <.01) and was reflected by increased total water content in most tissues in all groups. The albumin and protein masses remained constant in all groups throughout the study. CONCLUSION: Pretreatment with methylprednisolone, vitamin C, or alpha-trinositol was unable to prevent the increased fluid extravasation rate during hypothermic cardiopulmonary bypass. These findings, together with the stability of the protein masses throughout the study, support the presence of a noninflammatory mechanism behind the cold-induced fluid leakage seen during cardiopulmonary bypass.
Assuntos
Anti-Inflamatórios/farmacologia , Antioxidantes/farmacologia , Ácido Ascórbico/farmacologia , Ponte Cardiopulmonar , Extravasamento de Materiais Terapêuticos e Diagnósticos/etiologia , Extravasamento de Materiais Terapêuticos e Diagnósticos/prevenção & controle , Hipotermia Induzida/efeitos adversos , Fosfatos de Inositol/farmacologia , Complicações Intraoperatórias/etiologia , Complicações Intraoperatórias/prevenção & controle , Metilprednisolona/farmacologia , Animais , Biomarcadores/sangue , Permeabilidade Capilar/efeitos dos fármacos , Modelos Animais de Doenças , Índices de Eritrócitos/efeitos dos fármacos , Índices de Eritrócitos/fisiologia , Espaço Extracelular/efeitos dos fármacos , Espaço Extracelular/fisiologia , Extravasamento de Materiais Terapêuticos e Diagnósticos/sangue , Feminino , Hematócrito , Complicações Intraoperatórias/sangue , Masculino , Modelos Cardiovasculares , Concentração Osmolar , Pressão Osmótica/efeitos dos fármacos , Volume Plasmático/efeitos dos fármacos , Volume Plasmático/fisiologia , Circulação Pulmonar/efeitos dos fármacos , Albumina Sérica/metabolismo , Suínos , Equilíbrio Hidroeletrolítico/efeitos dos fármacos , Equilíbrio Hidroeletrolítico/fisiologiaRESUMO
The wick method for sampling of interstitial fluid from subcutis was applied in fluid balance studies in young pigs. Colloid osmotic pressure was measured in serum (COPs) and interstitial fluid (COPi) using a membrane colloid osmometer. Our aims were to determine the 'true' COPi, and to find the optimal duration of wick implantation. In series I (n = 6) a 'crossover' experiment was performed using wicks soaked in different priming solutions (non-diluted and diluted serum protein solutions or isotonic salt solution). Circulatory arrest was induced just before wick insertion in order to eliminate the vascular part of the acute inflammation. In series II (n = 6) wicks were removed in sequence after 60, 90, 120 and 180 min sampling time in anaesthetized pigs in vivo. COPs, COPi and haematocrit (HCT) together with haemoglobin (Hgb), serum albumin and total protein concentrations were determined in the same animals. In series I average COPs and COPi were 13.7 (1.4) and 7.2 (1.4) mmHg respectively (SD). In series II the optimal wick implantation times were estimated to be 60-90 min for wicks soaked in diluted protein solution, and 90-120 min for dry and saline-soaked wicks. COPs averaged 13.0 (0.7) mmHg, HCT 30.0 (1.6)%, Hgb 8.3 (0.9) g/dl, s-albumin 22.7 (0.6) g/l and s-protein 47.3 (2.3) g/l. Compared to commonly reported reference values, we found surprisingly low values for most of the measured variables. This may be related to the fact that we used immature pigs. An analysis of the validity of the wick method based on our own results and published reports is presented. We conclude that sampling of interstitial fluid with subcutaneous wicks is easy to perform in young pigs. However, the COP-values measured in wick fluid have to be carefully evaluated especially when sampling is performed in vivo.
Assuntos
Espaço Extracelular , Manejo de Espécimes/métodos , Anestesia , Animais , Estudos de Avaliação como Assunto , Pressão Osmótica , Manejo de Espécimes/normas , SuínosRESUMO
The domestic pig is a useful model in certain areas of biomedical research. Effective use of this species is often encumbered by lack of reference values in conscious as well as anaesthetized animals. Anaesthesia itself influences physiological and biological variables; the anaesthetic technique often affects experimental results. The relationship between anaesthesia and haemodynamics is well characterized in man, but less established in pigs. We studied the effect of midazolam-fentanyl-isoflurane anaesthesia in six immature, male, domestic pigs (Norwegian landrace). Haemodynamic variables (heart rate, arterial systolic, mean, diastolic pressures, pulmonary systolic, mean, diastolic pressures, pulmonary capillary wedge pressure), tissue perfusion, lymph flow (thoracic duct) were recorded for 3 h in animals with open chest through midline sternotomy. Variables relevant to fluid balance, e.g. interstitial hydrostatic pressure (Pi), serum-colloid osmotic pressure (s-COP) and serum-albumin (s-albumin) and -protein (s-protein) concentrations were measured. With the chosen anaesthetic technique haemodynamic variables, including lymph flow, and laboratory variables remained constant during the study period. Most variables were similar to conditions in humans. In contrast to adult humans exposed to the same anaesthetic technique, these pigs had lower haemoglobin-, s-albumin- and s-protein concentrations. A finding which may reflect immaturity. Liver and lung perfusion decreased significantly during the study period whereas perfusion of the other organs studied remained constant. Lack of responses to defined noxious stimuli during the study period suggest adequate analgesia. We conclude that midazolam, fentanyl and isoflurane provide cardiovascular stability including normal microvascular fluid exchange, which are essential elements for securing the quality of results obtained during cardiovascular research in anaesthetized pigs.
Assuntos
Anestesia/veterinária , Fentanila/administração & dosagem , Hemodinâmica/efeitos dos fármacos , Isoflurano/administração & dosagem , Midazolam/administração & dosagem , Suínos/fisiologia , Equilíbrio Hidroeletrolítico/efeitos dos fármacos , Animais , Pressão Sanguínea/efeitos dos fármacos , Resistência Capilar , Frequência Cardíaca/efeitos dos fármacos , Hemoglobinas/análise , Masculino , Pressão Osmótica/efeitos dos fármacos , Fluxo Sanguíneo Regional/efeitos dos fármacos , Suínos/sangueRESUMO
Based on measurements of the circulating red blood cell volume (V(RBC)) in seven anaesthetized piglets using carbon monoxide (CO) as a label, plasma volume (PV) was calculated for each animal. The increase in carboxyhaemoglobin (COHb) concentration following administration of a known amount of CO into a closed circuit re-breathing system was determined by diode-array spectrophotometry. Simultaneously measured haematocrit (HCT) and haemoglobin (Hb) values were used for PV calculation. The PV values were compared with simultaneously measured PVs determined using the Evans blue technique. Mean values (SD) for PV were 1708.6 (287.3)ml and 1738.7 (412.4)ml with the CO method and the Evans blue technique, respectively. Comparison of PVs determined with the two techniques demonstrated good correlation (r = 0.995). The mean difference between PV measurements was -29.9 ml and the limits of agreement (mean difference +/-2SD) were -289.1 ml and 229.3 ml. In conclusion, the CO method can be applied easily under general anaesthesia and controlled ventilation with a simple administration system. The agreement between the compared methods was satisfactory. Plasma volume determined with the CO method is safe, accurate and has no signs of major side effects.
Assuntos
Monóxido de Carbono , Volume Plasmático/veterinária , Suínos/fisiologia , Administração por Inalação , Anestesia Geral , Animais , Determinação do Volume Sanguíneo/métodos , Determinação do Volume Sanguíneo/veterinária , Monóxido de Carbono/administração & dosagem , Carboxihemoglobina/metabolismo , Azul Evans/administração & dosagem , Hematócrito , Hemoglobinas/análise , Injeções Intravenosas , Volume Plasmático/fisiologia , Reprodutibilidade dos Testes , Espectrofotometria/instrumentação , Fatores de TempoRESUMO
BACKGROUND: Increased intra-abdominal pressure (IAP) elevates thoracic pressure and airway pressures and reduces lung compliance in humans and laboratory animals. We studied respiratory alterations and arterial blood gas changes in pigs with IAP maintained at 20 mmHg or 30 mmHg for 3 h. METHODS: Domestic pigs of both sexes weighing 30.0 +/- 5.1 kg (mean +/- SD) (n = 21) were divided into three groups. The animals were anesthetized and kept at 20 mmHg IAP (n = 7) or 30 mmHg IAP (n = 7) for 3 h. The third group (n = 7) served as control without an elevated IAP. We recorded respiratory alterations and changes in acid-based parameters at baseline and after 90 min and 180 min of increased IAP. RESULTS: No significant hypoxia or hypercarbia was found in animals with an IAP of 20 mmHg IAP. At an IAP of 30 mmHg, pO2 decreased to an average 19.6 kPa and pCO2 increased to about 6 kPa, and the animals were slightly acidotic. Airway pressure increased significantly and lung compliance decreased in both groups of elevated IAP. CONCLUSION: In our porcine model, an IAP of 20 mmHg or higher for 3 h is harmful for the respiratory function of the animals due to deterioration of respiratory parameters, increased airway pressure and decreased lung compliance.
Assuntos
Abdome/fisiopatologia , Sistema Respiratório/fisiopatologia , Equilíbrio Ácido-Base/fisiologia , Análise de Variância , Anestesia Geral , Animais , Gasometria , Modelos Animais de Doenças , Feminino , Hemoglobinas/análise , Infusões Parenterais/efeitos adversos , Intubação Intratraqueal , Soluções Isotônicas/administração & dosagem , Complacência Pulmonar/fisiologia , Masculino , Pressão/efeitos adversos , Testes de Função Respiratória , Solução de Ringer , Suínos , Volume de Ventilação Pulmonar/fisiologia , Fatores de TempoRESUMO
BACKGROUND: Cardiopulmonary bypass (CPB) as used for cardiac surgery and for rewarming individuals suffering deep accidental hypothermia is held responsible for changes in microvascular fluid exchange often leading to edema and organ dysfunction. The purpose of this work is to improve our understanding of fluid pathophysiology and to explore the implications of the changes in determinants of transcapillary fluid exchange during CPB with and without hypothermia. This investigation might give indications on where to focus attention to reduce fluid extravasation during CPB. METHODS: Published data on "Starling variables" as well as reported changes in fluid extravasation, tissue fluid contents and lymph flow were analyzed together with assumed/estimated values for variables not measured. The analysis was based on the Starling hypothesis where the transcapillary fluid filtration rate is given by: JV=Kf [Pc-Pi-sigma(COPp-COPi)]. Here Kf is the capillary filtration coefficient, sigma the reflection coefficient, P and COP are hydrostatic and colloid osmotic pressures, and subscript 'c' refers to capillary, 'i' to the interstitium and 'p' to plasma. RESULTS AND CONCLUSION: The analysis indicates that attempts to limit fluid extravasation during normothermic CPB should address primarily changes in Kf, while changes in both Kf and Pc must be considered during hypothermic CPB.
Assuntos
Permeabilidade Capilar/fisiologia , Ponte Cardiopulmonar , Temperatura , Animais , Síndrome de Vazamento Capilar/etiologia , Síndrome de Vazamento Capilar/fisiopatologia , Ponte Cardiopulmonar/efeitos adversos , Espaço Extracelular/fisiologia , Pressão Hidrostática , Hipotermia Induzida , Linfa/fisiologia , Pressão Osmótica , Suínos , Equilíbrio Hidroeletrolítico/fisiologiaRESUMO
BACKGROUND: Edema, generalized overhydration and organ dysfunction commonly occur in patients undergoing open-heart surgery using cardiopulmonary bypass (CPB) and induced hypothermia. Activation of inflammatory reactions induced by contact between blood and foreign surfaces are commonly held responsible for the disturbances of fluid balance ("capillary leak syndrome"). We used an online technique to determine fluid shifts between the intravascular and the interstitial space during normothermic and hypothermic CPB. METHODS: Piglets were placed on CPB (fixed pump flow) via thoracotomy in general anesthesia. In the normothermic group (n=7), the core temperature was kept at 38 degrees C prior to and during 2 h on CPB, whereas in the hypothermic group (n=7) temperature was lowered to 28 degrees C during bypass. The CPB circuit was primed with acetated Ringer's solution. The blood level in the CPB circuit reservoir was held constant during bypass. Ringer's solution was added when fluid substitution was needed (falling blood level in the reservoir). In addition to invasive hemodynamic monitoring, fluid input and losses were accurately recorded. Inflammatory mediators or markers were not measured in this study. RESULTS: Cardiac output, s-electrolytes and arterial blood gases were similar in the two groups in the pre-bypass period. At start of CPB the blood level in the machine reservoir fell markedly in both groups, necessitating fluid supplementation and leading to a markedly reduced hematocrit. This extra fluid need was transient in the normothermic group, but persisted in the hypothermic animals. After 2 h of CPB the hypothermic animals had received 7 times more fluid as compared to the normothermic pigs. CONCLUSION: We found strong indications for a greater fluid extravasation during hypothermic CPB compared with normothermic CPB. The experimental model using the CPB-circuit reservoir as a fluid gauge gives us the opportunity to study further fluid volume shifts, its causes and potential ways to optimize fluid therapy protocols.
Assuntos
Ponte Cardiopulmonar , Equilíbrio Hidroeletrolítico , Animais , Hemodiluição , Hemodinâmica , Masculino , SuínosRESUMO
BACKGROUND: Hypothermia, commonly used for organ protection during cardiopulmonary bypass (CPB), has been associated with changes in plasma volume, hemoconcentration and microvascular fluid shifts. Fluid pathophysiology secondary to hypothermia and the mechanisms behind these changes are still largely unknown. In a recent study we found increased fluid needs during hypothermic compared to normothermic CPB. The aim of the present study was to characterize the distribution of the fluid given to maintain normovolemia. In addition, we wanted to investigate the quantity and quality of the fluid extravasated during hypothermic compared to normothermic CPB. METHODS: Two groups of anesthetized piglets were studied during 2 h of hypothermic (28 degrees C) (n=7) or normothermic (38 degrees C) (n=7) CPB. Net fluid balance (input-output) was recorded. Changes in colloid osmotic pressures of plasma (COPp) and interstitial fluid (COPi), plasma volume (PV), hemoglobin (Hb), hematocrit (HCT), mean corpuscular volume (MCV), s-osmolality, s-albumin and s-total protein was followed throughout the experiments. Fluid extravasation rate was calculated. In addition, total tissue water content was measured and compared with a control group (n=6) (no CPB). RESULTS: During hypothermic compared with normothermic CPB, the average net positive fluid balance from 10-120 min of extracorporeal circulation was 1.35+/-0.06 ml x kg(-1) x min(-1) and 0.33+/-0.03 ml x kg(-1) x min(-1) respectively (P<0.0001). We found a marked increase in fluid extravasation during hypothermic CPB. The extravasation rate during hypothermia was 1.8+/-0.2 ml x kg(-1) x min(-1), (1st hour) and 1.1+/-0.2 ml x kg(-1) x min(-1) (2nd hour) compared with 0.8+/-0.2 ml x kg(-1) x min(-1), and 0.1+/-(0.1) ml x kg(-1) x min(-1) during normothermia, respectively (P<0.01). The total intravascular protein and albumin masses remained constant in both groups. Following hypothermic CPB, the water content increased significantly in all tissues and organs. CONCLUSION: During hypothermic CPB an increased extravasation of fluid from the intravascular to the interstitial space was found. As no leakage of proteins could be demonstrated, based on stable values for albumin and protein masses throughout the experiments, the extravasated fluid contained mainly water and small solutes.
Assuntos
Permeabilidade Capilar/fisiologia , Ponte Cardiopulmonar/efeitos adversos , Hipotermia Induzida/efeitos adversos , Albuminas/metabolismo , Animais , Volume Sanguíneo/fisiologia , Água Corporal/metabolismo , Monóxido de Carbono/sangue , Hemodinâmica/fisiologia , Masculino , Suínos , TermodiluiçãoRESUMO
BACKGROUND: Hypothermic cardiopulmonary bypass (CPB) is associated with capillary fluid leak and edema generation which may be secondary to hemodilution, inflammation and hypothermia. We evaluated how hypothermia and different cooling strategies influenced the fluid extravasation rate during CPB. METHODS: Fourteen piglets were given 60 min normothermic CPB, followed by randomization to two groups: 1: rapid cooling (RC-group) ( approximately 15 min to 28 degrees C); 2: slow cooling (SC-group) ( approximately 60 min to 28 degrees C). Ringer's solution was used as CPB prime and for fluid supplementation. Fluid input/losses, plasma volume, colloid osmotic pressures (plasma, interstitial fluid), hematocrit, serum-proteins and total tissue water (TTW) were measured and fluid extravasation rates calculated. RESULTS: Start of normothermic CPB resulted in a 25% hemodilution. During the first 5-10 min the fluid level of the reservoir fell markedly due to an intravascular volume loss necessitating fluid supplementation. Thereafter a steady state was reached with a constant fluid need of 0.14 +/- 0.04 ml kg-1 min-1. After start of cooling the fluid needs increased in the following 30 min to 0.91 +/- 0.11 ml kg-1 min-1 in the RC group (P < 0.001) and 0.63 +/- 0.10 ml kg-1 min-1 in the SC-group (P < 0.001) with no statistical between-group differences. Fluid extravasation rates after start of hypothermic CPB increased from 0.20 +/- 0.08 ml kg-1 min-1 to 0.71 +/- 0.13 (P < 0.01) and 0.62 +/- 0.13 ml kg-1 min-1 (P < 0.05) in the RC- and SC-groups, respectively, without any changes in degree of hemodilution. TTW increased in most tissues, whereas the intravascular albumin and protein masses remained constant with no between group differences. CONCLUSION: Hypothermia increased fluid extravasation during CPB independent of cooling strategy. Intravascular albumin and protein masses remained constant. Since inflammatory fluid leakage usually results in protein rich exudates, our data with no net protein leakage may indicate that mechanisms other than inflammation could contribute to fluid extravasation during hypothermic CPB.