Small Ani. Sx- Approaches to the Thorax

kelseyfmeyer's version from 2016-03-05 14:32

intro+ lateral thoracotomies R vs L side IC space stuff

Question Answer
should you be seeing thymus in thoracic cavity of adult?no, should regress with age
what are the 3 main approaches you can use to access the thoracic cavity?(1) Lateral thoracotomy (2) Median sternotomy (3) Transthoracic
a Lateral thoracotomy can be performed in what three ways?(1) Intercostal (2) Rib resection (3) Periosteal stripping and rib resection (not common)
what IS a Transthoracic approach?bilateral lateral thoracotomy connected across sternum (RARELY done)
which structures are accessible from the RIGHT side (right lateral thoracotomy)eso, Cardiopulmonary bypass, Cr intermediate and ca lung lobectomy, thoracic duct in the DOG
When is right side (lateral) approach usually used?RIGHT side approach rarely used unless just working with the lungs themselves... and thoracic duct in dog (8th intercostal space)
which is the most common/useful lateral approach- L or R?Left
RIGHT lateral approach--> If there is a Esophageal foreign body at heart base...which IC space?4th
RIGHT lateral approach--> If you wish to perform a cardiopulmonary bypass...which IC space?4th
RIGHT lateral approach--> if you want to perform a CRANIAL lung lobectomy, which IC space?5th
RIGHT lateral approach--> if you want to perform a INTERMEDIATE lung lobectomy, which IC space?6th
RIGHT lateral approach--> if you want to perform a CAUDAL lung lobectomy, which IC space?7th
(which side of the body has the 3 lung lobes?)right
*RIGHT lateral approach--> who has the thoracic duct on the right side, and which IC space do you need to be at for it?DOG, 8th
which structures are accessible from the LEFT side of the thorax?Cr thoracic duct (all sp), most of heart vasculature/base, L Cr and Ca lung lobes, thoracic ducts IN CAT, Ca eso.
LEFT lateral approach--> where would you find the Cr. thoracic duct?3rd IC space
LEFT lateral approach--> IF you need to fix a PDA, PS, PRAA, or access the pericardium, which IC space should you be at?4th
LEFT lateral approach--> which IC space for a Cranial lung lobectomy?5th
LEFT lateral approach--> which IC space for a Caudal lung lobectomy?7th
LEFT lateral approach--> who has the thoracic duct on the left side, and which IC space do you need to be at for it?CAT, 8th
LEFT lateral approach--> which IC space for seeing Caudal esophagus?9th

Left 4th lateral thoracotomy + Median sternotomy (talking about lateral unless specified)

Question Answer
what are you looking at anatomically if you are at the left 4th lateral thoracotomy?The base of the heart!
Left 4th Lateral Thoracotomy--> how do you approach? (steps to get into T cavity- 6 steps)(1) Elevate thorax so that 4th interspace is highest point (2) Incision parallels rib (3)Cutaneous muscle transected (4)Latissimus dorsi muscle transected or retracted dorsally (5) Leaflets of serratus ventralis muscle bluntly separated, ventral to dorsal (6) Cut across intercostal muscles (more on this in diff card) (7) Incise pleura
explain how you should cut across IC mm... which direction? where?transect ventral to dorsal! and stay away from neurovascular bundle at caudal margin of 4th rib
Latissimus dorsi muscle transected or retracted dorsally--> what is positioning like?Elevate thorax so that 4th interspace is highest point (and towel helps separate ribs a bit), so looks like:
how should you clip for a Left 4th Lateral Thoracotomy?clip from mid abdomen to spine, to thoracic inlet, to sternum.
what will you need to regain neg pressure after done being in thoracic cavity?thoracostomy tube (basically drainage tube, so remember! NEVER THROUGH PRIMARY INCISION)
where do you cut the IC mms? (where do you wanna do, NOT go?)follow curvature of rib dorsally and ventrally with metzenbaums- stay away from caudal edge of rib bc v.a.n. there- make sure incision not to close to internal thoracic a and v (so don't extend incision below costochondral junction
how do you make an incision for the left 4th lateral thoracotomy?make a curved incision following curve of rib at 4th ICS. cut skin and sq, mm there is latissimus dorsi- linked to pectoral mm via CT. below latissimus is seraatus ventralis(fan) and then ventral to that is scalenus- wide band and large aponeurosis- cut scalenus in half. bluntly seperate mm bellies- then partial lift up insertion of belly on the rib. so dont have to suture mm- and dont have to create scar tissue in mm bc wont work properly. direction of intercostal mm- tells u which is internal and external.
If you open the thorax what must you know about the pt's respiration?NO NEG PRESSURE--> CAN'T BREATHE ON THEIR OWN. Will need a respirator or will need to be bagged.
Normally, you cannot cause more than 20cmH2O pressure to respirate pt. How does opening the thorax change this?can actually give a little more pressure if needed, because structures aren't in the way of expansion
before you can cut into the L. dorsi mm, what must you do?separate pecs from it (sever lats but DONT sever/cut serratus ventralis)
after you slide finger under L. dorsi and count ribs to make sure you're in the right place, what do you do with the serratis ventralis?make blunt dissection and then partially disengage from insertion
If you are working on heart, what must you do with the lungs (and how do you prepare lungs for this)ask anesthetist to expand lungs, but only with o2 (so turn vaporizer off) so can pack lungs with O2, bc if working on heart, need to push lung in ca direction and use sponges to keep separated or collapsed in a ca direction
If you are near the heart, you probably see the phrenic nerve. How does it run? What happens if you damage the left phrenic nerve? what if you damage both?phrenic nn crossing in oblique fashion on left side- if damage one side- hemiparalysis of diaphragm- and if cut both- can still breathe- bc intercostal mm maintain breathing- main resp mm!!! thats why animals can be ok w/ diaphragmatic hernias.
If you are near the heart, you can probably see the vagus nn. how does it run? what does it do?dorsal and ventral to esophagus. there is also recurrent laryngeal n (branch of vagus) surrounding ligamentum ateriosum. it innervates larynx and damage to this n causes laryngeal paralysis
how do you go about closure of the left 4th lateral thoracotomy? ( 4 steps)(1) Place thoracostomy tube (2) Preplace sutures around ribs and tie (3) Routine closure of musculature (4) Routine closure of skin
how do you close intercostal mm?*DO NOT SUTURE IC MM!!!!!!!!
How do you close the cutaneous trunci?Close cutaneous trunci with subcutaneous tissue in small patients
When closing, what should you know about the positioning of the ribs?***DO NOT OVERLAP RIBS (will fuse and cause restriction on thorax.)
Thoracostomy Tube Placement--> 3 steps for this?(1) Stab incision in skin and subcutaneous tissue 2-3 intercostal spaces (he also said 3-4) dorsal and caudal to thoracotomy incision (2) Tunnel cranially 1-2 intercostal spaces, enter pleural space, position tube in thorax (3) Place purse-string or chinese finger-trap suture in skin around tube
When you've already placed your thoracostomy tube and you are ready to close the abdomen, what should you ask anesthesia to do, and why?ask anesthisia to give a sigh (20-30 cm h2o) and make sure totally expanded- dont want atelectasis. slide finger over lung surface to push air into any unexpanded areas.
How should the tube be positioned inside of the thorax?caudal dorsal to ventral cranial . tip of tube should be thoracic inlet near the cranial mediastinum
If you are very concerned about damaging the neurovascular bundle, how can you close the ribs together?drill hole through rib and thread suture through that
what are the three ways to close the ribs back together?(1) suture around two ribs (caution- watch for neurovascular bundle) (2) drill hole through rib to avoid NV bundle (3) If rib removed, sew remnants together of CT (dont really remove ribs anymore tho)
**which side of the rib does the neurovascular bundle sit on?CAUDAL side of rib
how will you assure that there will be no direct communication to outside from the thoracic cavity via your incisions and sutures?Because you left the belly of the serratus ventralis intact, it will lay over the incised IC space.
are you concerned about suture lines overlapping and causing problems, since so many mm need to be stitched?no, because the mm all lay in different directions and areas so no overlap
How might you ensure that the patient will respirate better after the procedure?ANALGESIA! Do a line block with lidocaine 1-2 spaces cr and ca of suture line. Less pain= breathe normally
when do you maintain chest tube until?until plural space is free of other air or other fluids (technically until 2ml/kg production of fluids, bc tube naturally will cause this much production, so take out at that time to prevent FB probs, such as making more fluid)
3 ways to provide analgesia for the pt?(1) IC nn blocks (2) narcotic analgesics (3) intrapleural bupivicaine
three indications for a median sternotomy?(1) Access to entire lung field for exploratory surgery (2) Subtotal pericardectomy (3) Aortic valve replacement
how do you get through the sternum in a Median sternotomy? what caution should you take with this tool?use a recip saw-- little prong on end is called shoe= prevents blade from going farther than it should. Need to have syringe of water on hand to keep saw cool or will burn bone. Don't split sternum entire way if don't have to
explain procedure for IC nerve blockdorsally and ventrally where incision is and then 1-2 ICS cranially and caudal- will help allow patient to breath normally
what are some things you will need to cut through to do the median sternotomy?sternobrae and pectoralis mm
when you cut through sternum, you will notice it is full of marrow and will be oozing blood. how can you help with this problem?can use "bone wax" which is specially treated bees wax
3 basic steps for closing a median sternotomy?(1) Thoracostomy tube (s) placed (2) Sternebrae closed with orthopedic wire (3) Remaining tissues closed routinely
why must you make sure you close the sternum very well and securely with the orthopedic wire?close well otherwise micromotion-- painful and heals slowly
explain how to close sternummust use orthopedic wire and make sure very tight and secure- to prevent sharp, cut ends from hurting skin, "pigtail" them by bending them against the sternum
for a median sternotomy, where do you place the thoracostomy tube?Stab incision over 7th-9th intercostal space. Then Tunnel cranially 1-2 spaces to enter pleural cavity
advantages of the median sternotomy?Access to entire thoracic cavity
disadvantages of the median sternotomy?(1) More lengthy and more difficult procedure (2) Increased morbidity: More severe postoperative pain, More severe physical dysfunction - patient may be unable to ambulate without assistance
when do you want to STOP ventilation?when you are making stab incision with a hemostat into the thoracic cavity through IC mm
thoracostomy tube is what kinda tube?usually foley cath
incision where for median sternotomy?from xiphoid to manubrium