[Presacral haemorrhage during rectal cancer resection: morphological and hydrodynamic considerations]. / Hemorragia presacra durante la resección rectal por cáncer. Consideraciones morfológicas e hidrodinámicas.

INTRODUCTION: Our aim is to identify the location and size of the anterior foramina of sacral vertebral bodies and analyse the haemodynamic variables that could influence the haemorrhagic severity of the injury of the presacral venous plexus. MATERIALS AND METHODS: Using computed axial tomography the morphological data of 70 sacral bones in 67 patients with rectal cancer were recorded, as well as measuring the height between the vena cava and S5. After transfemoral catheterisation the inferior vena cava pressure was recorded in 10 patients with rectal cancer. Hydrodynamic principles, according to Bernoulli's Law, were applied to calculate sacral venous plexus pressure, and the flow rate according to the calibre of a hypothetical venous injury. RESULTS: The maximum diameter ranged from 0.5mm to 4mm in 22% of the cases. All foramina of 2 or more millimetres were located in the S4-S5 region. Sacral plexus venous pressure in lithotomy was almost double the inferior vena cava pressure in normal position. Blood flow ranged from 498 to 1,994 ml/min for injuries of sizes between 2 and 4mm, respectively. CONCLUSIONS: Larger calibre foramina are found in vertebral bodies of S4-S5. Venous injury at these levels can reach a flow rate of 2 l/min.

Hemorragia presacra durante la resección rectal por cáncer. Consideraciones morfológicas e hidrodinámicas / Presacral haemorrhage during rectal cancer resection: Morphological and hydrodynamic considerations

Introducción Nuestro objetivo ha sido identificar la localización y tamaño de los forámenes anteriores de sus cuerpos vertebrales y analizar las variables hemodinámicas que pudiesen influir en la gravedad hemorrágica por lesión del plexo venoso sacro. Material y método Se registraron los datos morfológicos de 70 huesos sacros. En 67 pacientes con cáncer rectal, mediante tomografía axial computarizada, se registran las mediciones de altura entre vena cava y S5. Tras cateterización transfemoral se registró la presión de la vena cava inferior en 10 pacientes con cáncer rectal. Aplicamos los principios generales de la hidrodinámica, según la Ley de Bernoulli, calculando la presión venosa del plexo sacro en posición de litotomía y el caudal de flujo según el calibre de una hipotética lesión venosa. Resultados En el 22% de los cuerpos vertebrales sacros existían forámenes cuyo diámetro máximo oscilaba entre 0,5 y 4mm. Todos los forámenes de 2 o más de 2mm estaban localizados en S4-S5. La presión venosa del plexo sacro en posición de litotomía se aproxima al doble de la presión venosa de la vena cava en posición normal. El caudal oscila entre 498 y 1.994ml/m. para lesiones de calibre entre 2mm y 4mm respectivamente. Conclusiones Los forámenes de mayor calibre se sitúan en los cuerpos vertebrales de S4-S5. La lesión venosa a esos niveles puede alcanzar un caudal de flujo de 2 l/m (AU)

Introduction Our aim is to identify the location and size of the anterior foramina of sacral vertebral bodies and analyse the haemodynamic variables that could influence the haemorrhagic severity of the injury of the presacral venous plexus. Materials and methods Using computed axial tomography the morphological data of 70 sacral bones in 67 patients with rectal cancer were recorded, as well as measuring the height between the vena cava and S5. After transfemoral catheterisation the inferior vena cava pressure was recorded in 10 patients with rectal cancer. Hydrodynamic principles, according to Bernoulli's Law, were applied to calculate sacral venous plexus pressure, and the flow rate according to the calibre of a hypothetical venous injury. Results The maximum diameter ranged from 0.5mm to 4mm in 22% of the cases. All foramina of 2 or more millimetres were located in the S4-S5 region. Sacral plexus venous pressure in lithotomy was almost double the inferior vena cava pressure in normal position. Blood flow ranged from 498 to 1,994ml/min for injuries of sizes between 2 and 4mm, respectively. Conclusions Larger calibre foramina are found in vertebral bodies of S4-S5. Venous injury at these levels can reach a flow rate of 2 l/min (AU)