Estimation of intracranial pressure by ultrasound of the optic nerve sheath in an animal model of intracranial hypertension

Antecedentes: La ecografía del diámetro de la vaina del nervio óptico (ONSD) se ha utilizado como alternativa no invasiva y rentable a la monitorización invasiva de la presión intracraneal (PIC). Sin embargo, aún se desconoce el comportamiento temporal del ONSD en la hipertensión intracraneal (HIC) y su alivio mediante infusión salina o cirugía. El objetivo de este estudio fue correlacionar la presión intracraneal (PIC) y la ultrasonografía de la vaina del nervio óptico (ONS) en un modelo animal experimental de HIC y determinar el intervalo necesario para que la ONSD vuelva a los niveles basales. Métodos: Se realizó un estudio experimental en 30 cerdos. La ONSD se evaluó mediante ecografía a diferentes PIC generadas por inflado intracraneal con balón, infusión salina y desinflado con balón, y se midió utilizando un catéter intraventricular. Resultados: Todas las variables obtenidas por ultrasonografía ONS como ONSD izquierdo, derecho y promedio (AON) fueron estadísticamente significativas para estimar el valor de la PIC. La ONSD cambió inmediatamente después del inflado del balón y volvió a los valores basales tras un retraso medio de 30 min después del desinflado del balón (p = 0,016). No se observó significación estadística en los valores de PIC y ONSD con la infusión de solución salina hipertónica. En este modelo porcino, la PIC y la ONSD mostraron una correlación lineal y la PIC pudo estimarse mediante la fórmula: -80,5 + 238,2 × AON. Conclusiones: En el presente estudio, la ecografía para medir la ONSD mostró una correlación lineal con la PIC, aunque se observó un breve retraso en volver a los niveles basales en el caso de alivio súbito de la HIC.Background: Ultrasound of the optic nerve sheath diameter (ONSD) has been used as a non-invasive and cost-effective bedside alternative to invasive intracranial pressure (ICP) monitoring. However, ONSD time-lapse behavior in intracranial hypertension (ICH) and its relief by means of either saline infusion or surgery are still unknown. The objective of this study was to correlate intracranial pressure (ICP) and ultrasonography of the optic nerve sheath (ONS) in an experimental animal model of ICH and determine the interval needed for ONSD to return to baseline levels. Methods: An experimental study was conducted on 30 pigs. ONSD was evaluated by ultrasound at different ICPs generated by intracranial balloon inflation, saline infusion, and balloon deflation, and measured using an intraventricular catheter. Results: All variables obtained by ONS ultrasonography such as left, right, and average ONSD (AON) were statistically significant to estimate the ICP value. ONSD changed immediately after balloon inflation and returned to baseline after an average delay of 30 min after balloon deflation (p = 0.016). No statistical significance was observed in the ICP and ONSD values with hypertonic saline infusion. In this swine model, ICP and ONSD showed linear correlation and ICP could be estimated using the formula: −80.5 + 238.2 × AON. Conclusion: In the present study, ultrasound to measure ONSD showed a linear correlation with ICP, although a short delay in returning to baseline levels was observed in the case of sudden ICH relief

Evaluation of intracranial pressure by ultrasound of the optic nerve sheath in an animal model of intracranial hypertension

Introdução: Monitoração invasiva da PIC é o único método aceito indiscriminadamente como forma para o diagnóstico seguro do aumento da pressão intracraniana (PIC), assim como para o tratamento da hipertensão intracraniana (HIC). Por ser invasiva, está sujeita a hemorragia, infecção e mau funcionamento. O ultrassom da bainha do nervo óptico (UBNO) destacase como alternativa não invasiva, custo benefício efetivo e disponível à beira leito. O objetivo deste estudo foi correlacionar PIC e ultrassonografia da bainha de nervo óptico em um modelo animal experimental de HIC. Materiais e Métodos: Foi realizado um estudo experimental em modelo animal de HIC com 30 suínos de ambos os sexos, 20 kg de peso corporal. Foram medidos simultaneamente o diâmetro da bainha do nervo óptico com ultrassom e a PIC com cateter intraparenquimatoso, além de dados laboratoriais e hemodinâmicos dos animais. Os valores foram correlacionados entre si para definir a aplicação deste procedimento em diferentes situações clínicas de HIC. Resultados: A média dos diâmetros das bainhas dos nervos ópticos obtidas por UBNO foram estatisticamente significativas para predizer o valor de PIC. Dessa forma, PIC pode ser predita usando a função linear: PIC = 238,2 x NO médio - 80,5. Conclusão: UBNO é um método confiável para predizer a PIC com inúmeras vantagens, como custo benefício efetivo, disponibilidade à beira leito dispensando a necessidade de transporte de pacientes além de não ser invasivo, estando livre das complicações dos cateteres intracranianos como hemorragia, infecção e mau funcionamentoIntroduction: Invasive monitoring of intracranial pressure (ICP) is the only method accepted indiscriminately as a form for the safe diagnosis and treatment of intracranial hypertension (IH). Being invasive, it is subject to hemorrhage, infection and malfunction. Ultrasound of the optic nerve sheath diameter (ONSD) stands out as a non-invasive alternative, cost effective and available at the bedside. The objective of this study was to correlate ICP and ultrasonography of the optic nerve sheath in an experimental animal model of cerebral hematoma. Materials and Methods: An experimental study was carried out with 30 pigs of both sexes, 20 kg body weight. The diameter of the optic nerve sheath with ultrasound and ICP with intraparenchymal catheter were measured simultaneously. The values were correlated with each other to define the application of this procedure in different clinical situations of IH. Results: The ONSD values were statistically significant to predict the ICP values. Thus, ICP can be predicted using the linear function: ICP = 238.2 x ONSD - 80.5. Conclusion: ONSD ultrassound is a reliable method to predict ICP with numerous advantages, such as cost effectiveness, availability at the bedside, eliminating the need to transport patients and freedom of the complications of intracranial catheters such as hemorrhage, infection and malfunctio

Evaluation of intracranial pressure by ultrasound of the optic nerve sheath in an animal model of intracranial hypertension

Introdução: Monitoração invasiva da PIC é o único método aceito indiscriminadamente como forma para o diagnóstico seguro do aumento da pressão intracraniana (PIC), assim como para o tratamento da hipertensão intracraniana (HIC). Por ser invasiva, está sujeita a hemorragia, infecção e mau funcionamento. O ultrassom da bainha do nervo óptico (UBNO) destacase como alternativa não invasiva, custo benefício efetivo e disponível à beira leito. O objetivo deste estudo foi correlacionar PIC e ultrassonografia da bainha de nervo óptico em um modelo animal experimental de HIC. Materiais e Métodos: Foi realizado um estudo experimental em modelo animal de HIC com 30 suínos de ambos os sexos, 20 kg de peso corporal. Foram medidos simultaneamente o diâmetro da bainha do nervo óptico com ultrassom e a PIC com cateter intraparenquimatoso, além de dados laboratoriais e hemodinâmicos dos animais. Os valores foram correlacionados entre si para definir a aplicação deste procedimento em diferentes situações clínicas de HIC. Resultados: A média dos diâmetros das bainhas dos nervos ópticos obtidas por UBNO foram estatisticamente significativas para predizer o valor de PIC. Dessa forma, PIC pode ser predita usando a função linear: PIC = 238,2 x NO médio - 80,5. Conclusão: UBNO é um método confiável para predizer a PIC com inúmeras vantagens, como custo benefício efetivo, disponibilidade à beira leito dispensando a necessidade de transporte de pacientes além de não ser invasivo, estando livre das complicações dos cateteres intracranianos como hemorragia, infecção e mau funcionamentoIntroduction: Invasive monitoring of intracranial pressure (ICP) is the only method accepted indiscriminately as a form for the safe diagnosis and treatment of intracranial hypertension (IH). Being invasive, it is subject to hemorrhage, infection and malfunction. Ultrasound of the optic nerve sheath diameter (ONSD) stands out as a non-invasive alternative, cost effective and available at the bedside. The objective of this study was to correlate ICP and ultrasonography of the optic nerve sheath in an experimental animal model of cerebral hematoma. Materials and Methods: An experimental study was carried out with 30 pigs of both sexes, 20 kg body weight. The diameter of the optic nerve sheath with ultrasound and ICP with intraparenchymal catheter were measured simultaneously. The values were correlated with each other to define the application of this procedure in different clinical situations of IH. Results: The ONSD values were statistically significant to predict the ICP values. Thus, ICP can be predicted using the linear function: ICP = 238.2 x ONSD - 80.5. Conclusion: ONSD ultrassound is a reliable method to predict ICP with numerous advantages, such as cost effectiveness, availability at the bedside, eliminating the need to transport patients and freedom of the complications of intracranial catheters such as hemorrhage, infection and malfunctio

The Effects of Induction and Treatment of Intracranial Hypertension on Cerebral Autoregulation: An Experimental Study

Background. This study aimed to analyse cerebral autoregulation (CA) during induction and treatment of intracranial hypertension (ICH) in an experimental model. Materials and Methods. Landrace and Duroc piglets were divided into mild and severe ICH groups. Four or seven millilitres of saline solution was infused into paediatric bladder catheter inserted in the parietal lobe (balloon inflation). After 1.5 h, a 3% saline solution was infused via venous catheter, and 30 min later, the bladder catheter balloon was deflated (surgery). The cerebral static autoregulation (sCA) index was evaluated using cerebral blood flow velocities (CBFV) obtained with Doppler ultrasound. Results. Balloon inflation increased ICP in both groups. The severe ICH group showed significantly lower sCA index values (p=0.001, ANOVA) after balloon inflation (ICH induction) and a higher sCA index after saline injection (p=0.02) and after surgery (p=0.04). ICP and the sCA index were inversely correlated (r=−0.68 and p<0.05). CPP and the sCA index were directly correlated (r=0.74 and p<0.05). Conclusion. ICH was associated with local balloon expansion, which triggered CA impairment, particularly in the severe ICH group. Moreover, ICP-reducing treatments were associated with improved CA in subjects with severe ICH