Parasternal Marcaine-Lidocaine Blocks

Mark M. Levinson, M.D.
Hutchinson Hospital
Hutchinson, KS, USA
mmlevinson@hsforum.com

Immediate control of postoperative pain is key to early extubation and mobilization. Patients who do not require postoperative ventilation can leave the ICU sooner and have much shorter lengths of stay (LOS).

Narcotics are effective pain relievers but have many deleterious side effects (sedation, confusion, respiratory depression, constipation, nausea). Benzodiazepenes provide relief of anxiety, but little analgesia. Ketorolac (Toradol) is very effective and does not cause respiratory depression, but all NSAIDS including Toradol have the potential to cause acute renal insufficiency and are relatively contraindicated in diabetics for this reason, thus limiting their usefulness.

I have been impressed that post-CABG patients who are extubated on the operating table have significantly reduced ICU and hospital LOS. Development of an on-table fast track extubation program requires close coordination with anesthesia providers so that short acting agents are used throughout the case. At the time of wound closure, agents can be titrated in a manner similar to emergence from other major cases (AAA resection, laparotomy, or thoracotomy). However, pain during emergence is usually treated by anesthesiology with narcotics, so the balance between pain relief and respiratory compromise can be quite delicate at times, especially in the elderly.

I have found that local infusion of an equal mixture of marcaine (bupvicaine 0.25%) and lidocaine (1%) into the parasternal tissues provides excellent analgesia. This simple maneuver, when applied correctly, sharply reduces the amount of narcotic needed to control pain during emergence from anesthesia. It has been the key step in my consistent use of on-table extubation and the QuickTime movie here shows how I perform the parasternal blocks.

There are 4 main points:

1) A large needle (18 guage) 2) 50:50 mixture of plain bupivicaine 0.25% and lidocaine 1%. No epinephrine is used 3) Infusion into the chest tube tracts, and 4) Infusion into each interspace along the sternal edge

It is important to understand the physiology of the drugs. First, the intercostal spaces are muscular tissue and the absorption rate of local anesthetics from muscle is fast. My anesthesia colleagues have informed me that absoption from the intercostal spaces is one of the fastest in the body.

Second, there is an upper limit on bupivicaine. At present, the top recommended dose is 1 cc per kg body weight for the plain 0.25% concentration. Doses higher than this are associated with dangerous cardiotoxicity.

With these two points in mind, I have achieved success with an equal mixture of bupivicaine 0.25% and lidocaine 1%. Neither contain epineprine. When I tried adding epinephrine to either solution, I caused tachycardia.

The maximum dose of the 50:50 mixture that I care to inject is 1 cc per kg body weight. Since the bupivicaine is diluted in half, this limits my injection to half of the upper dose, with the lidocaine providing additional early analgesia.

The exact placement of the injection is important. There are two main aspects:

1) When the incisions are made for the mediastinal tubes, bupivicaine-lidocaine solution is injected first before the tubes are placed. This is an important point. If this step is omitted, the mediastinal tube insertion sites are often the source of severe, focal pain while the rest of the sternum is painless. To infuse adequately, I perform the injection in the following manner. After the skin is divided, I pass the injecting needle all the way into the mediastinum in the same direction and angle as I plan to place the mediastinal tube. Then I inject while removing the needle. This penetrates the entire chest tube tract with local anesthetic. If I already have some tubes in place from earlier in the case, I start inside the lower wound and inject directly into the fascia surrounding these tubes.

2) Each interspace is infused with 2 or 3 cc of the local anesthetic mixture in the following manner. The second or third finger of my left hand is placed under the sternum to palpate the interspace along the sternal edge, similar to the manner in which I identify the interspace prior to sternal wire placement. The 18 guage injecting needle is used to explore the anterior interspace until it just barely penetrates the interspace lateral to the outside edge of the sternum. The needle does not go all the way through the interspace. Instead, pressure on the syringe injects fluid ahead of the needle tip, and the left hand can feel a "wheal" of fluid develop on the underside of the interspace. Once this sensation is felt, the parasternal tissues have enough local anesthetic to numb the periosteum and the anterior intercostal nerve branches. This maneuver is repeated in each interspace where a sternal wire will be placed.

The movie shows these maneuvers in a manner that is easier to understand. The technique has been very successful in reducing the need for narcotic during emergence from anesthesia.

There are other elements to successful on-table extubation, not the least of which is secure, meticulous hemostasis and normal cardiac hemodynamics. However, in the era of OPCAB, these are very achievable goals in a large number of patients. If done properly, a finished OPCAB is more like a vascular or carotid case than a traditional cross-clamp case. It is my position that if our anesthesiologists can routinely extubate a AAA resection on the table, or even such cases as lobectomies or pneumonectomies, then why not an OPCAB? In my experience, stable, dry patients can be extubated on the table with a combination of careful coordination with anesthesia to limit long acting agents during the case, patience during emergence, parasternal blocks, and occasionally Toradol or Versed.

For questions, please email me at mmlevinson@hsforum.com