In minimally invasive spine surgery (MISS) Bleeding control In minimally invasive spine surgery (MISS) Presenter’s name (Arial 20 pt) Authors: AOSpine MISS Taskforce Presenter’s title (Arial 20 pt) Version: July 1, 2019

Learning objectives Describe the different hemostasis options in MISS Describe how to perform hemostasis in a tubular surgery Identify the vascular anatomy in posterior, oblique, and lateral approaches Identify the different control tips for bleeding according to the approach Recognize the importance of hemostatic and soft-tissue management in MISS

Bleeding in MISS One of the core advantages in MISS compared with open techniques is reduced overall blood loss That does not mean that there will not be bleeding Skills to manage bleeding in MISS are similar in principle to open surgery but vary subtly

Bleeding management Prevention Simple, direct management Useful additional hemostatics Torrential bleeding

Prevention: bleeding is best avoided than managed Ensure anticoagulants are stopped appropriately (prescribed drugs and others, eg, fish oil) Ask about and manage any bleeding history/diathesis Patient positioning remains important, eg, a free-hanging abdomen in lumbar cases, head up for cervical cases Use blunt dissection techniques more than sharp dissection Bipolar vessels when encountered before dividing Recognize the detailed microanatomy—“the pars vessel is usually just here…”

Bleeding control It is important to recognize the different options for control of bleeding in tubular surgery: Energy: bipolar Pressure Hemostats

Vascular considerations in oblique and lateral approaches: In more than 90% of cases the median sacral vein drains into the left iliac vein The bifurcation of the cava is usually between L4 and L5 The iliolumbar vein anatomy is highly variable and limits left common iliac vein mobility The segmental artery is close to the middle portion of the vertebral body – exercise caution with pin or screw fixation here

Patient positioning The positioning of the patient is essential to avoid pressure on the abdomen and create venous engorgement in lumbar cases. Head up, with free shoulders is important in cervical cases. Engorged epidural plexus

Bleeding control The median sacral vein usually drains into the left common iliac vein

Bleeding control In anterolateral approaches, a fat window must be identified between the psoas and the artery

Bleeding control Avoid positioning pins near the medial part of the vertebral body The arrow indicates the height at which the segmental artery is located

Simple, direct management The mainstay of all our surgical practice—direct tie or clip, electrocautery, ‘pack and wait’ (ie, pressure) Direct tie of vessels in MISS is often impracticable and so clips are more commonly used. It is important that you know the clip lengths, applicator length and bulk, applicator angle of insertion, etc, BEFORE you need them for the first time. Know what your hospital has (and where they are….), and that it suits your operation

Simple, direct management Monopolar cautery is less commonly useful in MISS, so bipolar is preferred. Know the differing tip widths, instrument lengths and tip angles that are available to you. DO NOT use bipolar ‘blindly.’ Gentle slow dripping of saline down the legs of the bipolar may make it more effective during use. Use ‘bayonetted’ instruments

Simple, direct management Pack and wait—resist the temptation to ‘chase’ bleeding. Ensure you do not cause inadvertent iatrogenic neural or other damage with injudicious diathermy. ‘Pack and wait’ approach has served surgeons for generations and will continue to do so in MISS.

Useful additional hemostatics Systemic—tranexamic acid has been shown to be safe and effective in open surgery for blood loss reduction and should be considered in major surgeries and in patients with specific needs or concerns. Activated factor VII is occasionally used. Topical—there are a (very) large number of commercially available hemostatic agents available: Passive hemostats based on collagen, cellulose, and gelatins Active agents based on thrombins Sealants, such as fibrin-based sealants and synthetic glues

B. Note the control of epidural bleeding with a hemostatic Tubular surgery—we have as tools: pressure, bipolar energy and hemostatic B. Note the control of epidural bleeding with a hemostatic A. Epidural bleeding

Hemostatic in tubular surgery Hemostatic at the end of a tubular over the top

Topical hemostatics Passive topical hemostats act by providing a physical framework to which platelets can aggregate, allowing a clot to form over them. They come in differing forms of application, such as sponges, or gauze-like sheets. They are often used in addition to a ‘pack and wait’ approach.

Topical hemostatics Active hemostats are more costly and have an intrinsic biological component that directly activates the coagulation cascade. They contain thrombin, part of the final common coagulation pathway that converts fibrinogen to fibrin. Their advantage is in bypassing the general coagulation cascade proceeding straight to fibrin generation. Do not allow to contaminate cell salvage systems if used.

Topical hemostatics Sealants form a physical barrier that occludes flow from injured vessels. There are different types; fibrin-based sealants, cyanoacrylates, PEG polymers and albumin with glutaraldehyde. Fibrin sealants are designed to mimic the conversion of fibrinogen to fibrin, thus forming a stable clot which assists hemostasis. They contain fibrinogen and thrombin, and some may also contain antifibrinolytic agents, calcium chloride and Factor XIII.

Torrential bleeding Inform your anesthetist Decide the likely cause (arterial, venous, great vessel?) - Do you have the skills to manage it? Call colleague early if unsure - Is it torrential? For those new to a microscope, bleeding can seem very heavy even when it is not particularly Obtain temporary control while you prepare for definitive control - Pack, use active hemostatics if immediately available but do not wait for ‘mixing’ time. Arrange cell salvage, give TXA, could position changes help? Convert to open? - Have sutures, clips, grafts, biologics, staff and skills in OR that you need before removing packs.

Take-home messages Humans bleed when cut. Bleeding management is a core skill in conducting any surgery safely and effectively. MISS can produce challenges due to limitations of vision and access. Preoperative consideration is paramount, meticulous surgical technique is advantageous, and hemostatic agents, particularly active thrombin-based agents where available, make the issue far less challenging.