Donald H. Lambert Boston, Massachusetts Spinal - Epidural - [Combined Spinal Epidural]

Donald H. Lambert Boston, Massachusetts

Spinal Anesthesia l Advantages v. Disadvantages l Pharmacology of spinal agents l Addition of a vasoconstrictor l Baricity l Dosing l Complications

Spinal Anesthesia l Advantages v. Disadvantages l Pharmacology of spinal agents l Addition of a vasoconstrictor l Baricity l Dosing l Complications

Spinal Anesthesia l Advantages v. Disadvantages l Pharmacology of spinal agents l Addition of a vasoconstrictor l Baricity l Dosing l Complications

Spinal Anesthesia Agents

l The dosing in this study was 10 mg, 15 mg, and 20 mg of bupivacaine l The lowest dose limited spread l The lowest dose also resulted in more failures than the higher doses.

Spinal Anesthesia l Advantages v. Disadvantages l Pharmacology of spinal agents l Addition of a vasoconstrictor l Baricity l Dosing l Complications

Spinal Anesthesia l Advantages v. Disadvantages l Pharmacology of spinal agents l Addition of a vasoconstrictor l Baricity l Dosing l Complications

l The effect of baricity on the distribution of bupivacaine in spinal model l In spite of the crudeness of this model, the levels of anesthesia predicted by the model are remarkably similar to the levels of anesthesia observed in patients Hyperbaric Isobaric Hypobaric

Hyperbaric Isobaric Hypobaric

Spinal Anesthesia l Advantages v. Disadvantages l Pharmacology of spinal agents l Addition of a vasoconstrictor l Baricity l Dosing l Complications

Spinal Anesthesia l Dosing will affect Spread Duration Quality of Anesthesia u That is, the need for supplemental IV medication

l The duration of anesthesia with bupivacaine is dependent on the dose l Regression to T10 and T12 is similar despite the difference in concentration so long as the dose (mg) is the same l There is a tendency for the analgesia to be shorter with the 0.5% v. 0.75% bupivacaine l With lidocaine the motor block wears off more quickly with 1.5% v. 5% when equal doses are given.

Spinal Anesthesia l Advantages v. Disadvantages l Pharmacology of spinal agents l Addition of a vasoconstrictor l Baricity l Dosing l Complications

Spinal Anesthesia l I have been doing spinal anesthesia for 25 years l I spent the first 10 years trying to control the level of spinal anesthesia l I have failed l I have given up trying l If you know how to control the level of spinal anesthesia please tell me how it is done

Dosing Guidelines l Based on the spinal canal model (and many years in the trench) Hyperbaric solutions extend into the thoracic region Isobaric solution remain in the lumbar region l I give hyperbaric solutions for operations above the L1 dermatome and isobaric solutions for those below Hyperbaric Isobaric

Dosing Guidelines l Hernia operations and those operations whose innervation is by nerves above L1 HYPERBARIC l Those operations whose innervation is by nerves below L1 (pretty much all lower extremity operation including hip operations) ISOBARIC

CHOOSING A LOCAL ANESTHETIC FOR SPINAL ANESTHESIA BASE DECISION ON THE DURATION OF THE OPERATION

CHOOSING A LOCAL ANESTHETIC FOR SPINAL ANESTHESIA GIVE ENOUGH TO PROVIDE ADEQUATE ANESTHESIA ? CHLOROPRACAINE, ? ROPIVACAINE

Isobaric Spinal Anesthesia l Epidural Bupivacaine It says right on the bottle: Not for spinal anesthesia What is the value or wisdom behind using that agent? u It works great and I have used it since the 1980s. u I know of no reports of complications associated with using it. u Litigation for the off-labeled use of a drug has not appeared in the ASA closed claims database. Who would know? u Unless you wrote on your anesthesia record, I used the bupivacaine that is not for spinal anesthesia.

Spinal Anesthesia l Advantages v. Disadvantages l Pharmacology of spinal agents l Addition of a vasoconstrictor l Baricity l Dosing l Complications

Spinal Anesthesia l Complications Cardiac arrest Hypotension Headache Nerve injury

Unexpected cardiac arrest during spinal anesthesia: a closed claims analysis of predisposing factors Caplan, R A; et al. Unexpected cardiac arrest during spinal anesthesia: a closed claims analysis of predisposing factors. Anesthesiology 1988;68:5-11

Unexpected cardiac arrest during spinal anesthesia: a closed claims analysis of predisposing factors Caplan, R A; et al. Unexpected cardiac arrest during spinal anesthesia: a closed claims analysis of predisposing factors. Anesthesiology 1988;68:5-11 Caplan, R A; et al. Injuries Associated with Regional Anesthesia in the 1980s and 1990s: A Closed Claims Analysis. Anesthesiology. 2004;101:

Unexpected cardiac arrest during spinal anesthesia: a closed claims analysis of predisposing factors Caplan, R A; et al. Unexpected cardiac arrest during spinal anesthesia: a closed claims analysis of predisposing factors. Anesthesiology 1988;68:5-11

Unexpected cardiac arrest during spinal anesthesia: a closed claims analysis of predisposing factors Caplan, R A; et al. Unexpected cardiac arrest during spinal anesthesia: a closed claims analysis of predisposing factors. Anesthesiology 1988;68:5-11 Initial Clues of Impending Arrest

Unexpected cardiac arrest during spinal anesthesia: a closed claims analysis of predisposing factors Caplan, R A; et al. Anesthesiology 1988;68:5-11 and Mackey, D C, et al. Anesthesiology 1989;70: l Factors Predisposing to Asystole High level Loss of Cardiac Sympathetic Stimulation Unopposed Vagal Tone Decreased Venous Return u Empty Left Ventricle u Activation of Intracardiac Reflexes ? So-called Bezold-Jarisch Reflex or the so-called Vaso-vagal Syncope

Cardiac arrest during spinal anesthesia l How can this be prevented and/or treated? Maintain venous return at all cost Use epinephrine at the first sign of cardiac arrest Keats, A. S. Anesthesia mortality--a new mechanism. Anesthesiology 1988;68:2-4.

Sandra L. Kopp, et al Anesth Analg 2005; 100: Cardiac Arrest During Neuraxial Anesthesia: Frequency and Predisposing Factors Associated with Survival

Acta Anaesthesiol Scand 1997; 41: Severe complications associated with epidural and spinal anaesthesias in Finland A study based on patient insurance claims Aromaa U, Lahdensuu M, Cozanitis DA

Spinal Anesthesia Complications Hypotension (happens!) But, if you want to know something… it happens also when I do general anesthesia!!

The Two Components of Spinal Headache l There must have been a lumbar puncture l The headache is related to posture Worst when standing or sitting Gone or improved with recumbence

Effect of Age on the Incidence of Spinal Headache Vandam and Dripps, JAMA 1956;161: This and AARP discounts are two of the few advantages to aging!

There is a lower incidence of spinal headache in older patients One of the few advantages of aging!

Most frequent with lidocaine (10-34% incidence) More frequent with lithotomy position and knee arthroscopy VAS pain score averages 6 out of 10 Many rate the pain worse than their incision Can last up to three days Least frequent with bupivacaine How Safe are Spinals? n TNS/TRI

How Safe are Spinals?

Spinal Anesthesia l Is there a reasonable alternative to lidocaine? l What are the possibilities? Procaine ? Chloroprocaine (non-neurotoxic in isolated nerve) u recent data in rats indicates neural toxicity with i.t. infusion Prilocaine (low incidence of TRI, but neurotoxic in rat) Mepivacaine (same incidence of TRI as with lidocaine) Low dose bupivacaine ? Ropivacaine

Spinal Anesthesia l Advantages v. Disadvantages l Pharmacology of spinal agents l Addition of a vasoconstrictor l Baricity l Dosing l Complications

EPIDURAL ANESTHESIA l Advantages v. Disadvantages l Technique l Pharmacology of Specific Agents l Effect of Dose l Mechanism of Action l Addition of a Vasoconstrictor l Complications l Test Dose l Comparison with Spinal

EPIDURAL ANESTHESIA l Advantages l Disadvantages l Technique l Pharmacology of Specific Agents l Effect of Dose l Mechanism of Action l Addition of a Vasoconstrictor l Complications l Test Dose l Comparison with Spinal

EPIDURAL ANESTHESIA l Advantages l Disadvantages l Technique l Pharmacology of Specific Agents l Effect of Dose l Mechanism of Action l Addition of a Vasoconstrictor l Complications l Test Dose l Comparison with Spinal

EPIDURAL ANESTHESIA l Advantages l Disadvantages l Technique l Pharmacology of Specific Agents l Effect of Dose l Mechanism of Action l Addition of a Vasoconstrictor l Complications l Test Dose l Comparison with Spinal

Through the years many methods to locate the epidural space have come and gone. This attests to the difficulty associated with the performance of epidural anesthesia. The two methods that have stood the test of time appear to be loss of resistance to injection of air or saline.

EPIDURAL ANESTHESIA l Advantages l Disadvantages l Technique l Pharmacology of Specific Agents l Effect of Dose l Mechanism of Action l Addition of a Vasoconstrictor l Complications l Test Dose l Comparison with Spinal

EPIDURAL ANESTHESIA AGENTS DRUGCONC.DOSE VOLUMEDURATION (%)(mg)(ml)(min) CHLOROPROC LIDOCAINE MEPIVACAINE PRILOCAINE ROPIVACAINE BUPIVACAINE LEVOBUPIV ETIDOCAINE

EPIDURAL ANESTHESIA l Advantages l Disadvantages l Technique l Pharmacology of Specific Agents l Effect of Dose l Mechanism of Action l Addition of a Vasoconstrictor l Complications l Test Dose l Comparison with Spinal

Truisms on Dose l The more you put in The quicker it comes on The better the block The longer it lasts l The more you put in The more likely are you to cause toxicity

EPIDURAL ANESTHESIA l Advantages l Disadvantages l Technique l Pharmacology of Specific Agents l Effect of Dose l Mechanism of Action l Addition of a Vasoconstrictor l Complications l Test Dose l Comparison with Spinal

EPIDURAL ANESTHESIA l Advantages l Disadvantages l Technique l Pharmacology of Specific Agents l Effect of Dose l Mechanism of Action l Addition of a Vasoconstrictor l Complications l Test Dose l Comparison with Spinal

The are many potential sites where epidural local anesthetics can act. The highest concentrations of local anesthetic are found in the CSF and nerve roots. The lowest concentrations are found in the dorsal root ganglia and the substance of the spinal cord. All sites likely contribute to the mechanism of epidural anesthesia, but the most likely conclusion is that the epidural anesthesia comes about by an intrathecal action.

The largest and most difficult nerve root to block with epidural anesthesia is S1. The S1 root is the one which is most likely to be missed or poorly anesthetized.

EPIDURAL ANESTHESIA l Advantages l Disadvantages l Technique l Pharmacology of Specific Agents l Effect of Dose l Mechanism of Action l Addition of a Vasoconstrictor l Complications l Test Dose l Comparison with Spinal

Effect of Epinephrine on Peak Venous Plasma Level with Epidural Anesthesia l The more vasodilating agents - mepivacaine and lidocaine show the greatest epinephrine effect. l The lack of effect with prilocaine may be due to its good diffusion. l The lack of effect with etidocaine and bupivacaine due to their avid binding to lipids.

EPIDURAL ANESTHESIA l Advantages l Disadvantages l Technique l Pharmacology of Specific Agents l Effect of Dose l Mechanism of Action l Addition of a Vasoconstrictor l Complications l Test Dose l Comparison with Spinal

Cardiovascular Toxicity HYPERTENSION - TACHYCARDIA OWING TO CNS EXCITATION NEGATIVE INOTROPY DECREASED CARDIAC OUTPUT MILD - MODERATE HYPOTENSION PERIPHERAL VASODILATATION PROFOUND HYPOTENSION SINUS BRADYCARDIA CONDUCTION DEFECTS VENTRICULAR ARRYTHMIAS CARDIOVASCULAR COLLAPSE

Low doses of epidural local anesthetics have a CNS stimulating affect that counteracts vascular depression. With higher local anesthetic doses, cardiovascular depression is more apparent. Epinephrine contributes to vascular depression by its beta effect, which lower peripheral vascular resistance. Hypovolemia contributes to cardiovascular collapse (vaso- depressor syncope?). The deleterious effect of hypovolemia is counteracted by the addition of epinephrine to the local anesthetic. LEVEL T5T1T2-3T5T5 Lido (ug/ml) 4<4<4 Epinephrine Hypovolemia

LEVEL T5T1T2-3T5T5T5 Lido (ug/ml) 4<4<4<4 Epinephrine Hypovolemia

The Two Components of Spinal Headache l There must have been a lumbar puncture l The headache is related to posture Worst when standing or sitting Gone or improved with recumbence

Accidental puncture during labor epidural l About a 1% chance of less l About 60% will develop a headache l About 70% will require a blood patch

FDA WARNING ON LOW MOLECULAR WEIGHT HEPARIN StandardLMWH Mean Mol. Wt Saccharide units Anti X-a : Anti II-a Activity1:12:1 to 4:1 Plasma Protein BindingHighLow Endothelium BindingYes Weakly Dose Dependent ClearanceYesNo Small Dose Bio-availabilityPoor Good Platelet InhibitionStrongModerate Increases Vascular PermeabilityYes No

Guidelines for Regional Anesthesia in the Anticoagulated Patient See Consensus Statement at the ASRA Web site:

EPIDURAL ANESTHESIA l Advantages l Disadvantages l Technique l Pharmacology of Specific Agents l Effect of Dose l Mechanism of Action l Addition of a Vasoconstrictor l Complications l Test Dose l Comparison with Spinal

Components of an Epidural Test Dose l Cause a detectable increase the heart rate l Cause detection of a spinal injection but not produce a total spinal l Three ml of 1.5% lidocaine with epinephrine 5 ug/ml will do both l Unless the patient is beta blocked

Test Dose l Used to prevent intravascular injection of local anesthetic l Epinephrine most frequently advocated and most extensively studied 15 ug of epinephrine produces a tachycardia within 20 seconds Reliability diminished by beta blockade, aging, general or combined general-epidural anesthesia Mulroy, MF RAPM 27: ;2002

Test Dose Criteria for Positive Epinephrine Test Dose Patient under age 60, awake,HR increase > 20 bpm not on beta blocker Beta blockadeSBP increase > 15 torr Age over 60SBP increase > 15 torr HR increase > 9 bpm General AnesthesiaSBP increase > 13 torr HR increase > 8 bpm All changes in the first 120 seconds of injection Mulroy, MF RAPM 27: ;2002

Test Dose l When epinephrine is not practical Use moderate doses of local anesthetic while monitoring for CNS effects u 100 mg of lidocaine or chloroprocaine u 25 mg of bupivacaine u Requires non pre-medicated patient u Medication with midazolam will interfere Mulroy, MF RAPM 27: ;2002

Test Dose From Mulroy, MF RAPM 27: ;2002

Local Anesthetic Toxicity Rate of Injection l Slow rates of injection are less likely to result in systemic toxicity l Intermittent injections, at slow rates will lessen further the likelihood of systemic toxicity l These two steps, in my opinion, are better than a test dose of local anesthetic with epinephrine as tracer

Test Dose Quiz Epidural anesthesia for cesarean delivery is planned for a 30-year-old woman in labor. She has preeclampsia and takes propranolol for mitral valve prolapse. A test dose of 3 ml of 2% lidocaine containing 15 g of epinephrine is administered, and no change in heart rate is noted by palpation of the pulse. Prior to injection of more local anesthetic, blood is freely aspirated from the catheter. Explanations for failure of the intravenous test dose include: (1) The pain of labor masked the change usually seen with the test dose (2) Pre-existing beta-adrenergic blockade blunted the tachycardia from the intravenous epinephrine (3) Changes in pulse rate were too brief to be noted by palpation of the pulse (4) Preeclampsia decreased the sensitivity to exogenously administered catecholamines

EPIDURAL ANESTHESIA l Advantages l Disadvantages l Technique l Pharmacology of Specific Agents l Effect of Dose l Mechanism of Action l Addition of a Vasoconstrictor l Complications l Test Dose l Comparison with Spinal

Comparing spinal to epidural l Spinal easier to do l No chance systemic toxicity l Increased risk of neural toxicity l Duration too short l Low incidence of spinal headache l Epidural more difficult l Systemic toxicity possible l Less chance neural toxicity except with certain agents and accidental spinal injection l Unlimited duration l Incidence of spinal headache about the same as spinal

EPIDURAL ANESTHESIA l Advantages l Disadvantages l Technique l Pharmacology of Specific Agents l Effect of Dose l Mechanism of Action l Addition of a Vasoconstrictor l Complications l Test Dose l Comparison with Spinal

Good luck with your exam! If you still have unanswered questions OR If you have answers you want questioned You can contact me (no bunk): I will try to post these presentations on a web site: (Education Corner) Dont for get the dash between debunk and it

Components of an Epidural Test Dose l Cause a detectable increase the heart rate l Cause detection of a spinal injection but not produce a total spinal l Three ml of 1.5% lidocaine with epinephrine 5 ug/ml will do both l Unless the patient is beta blocked