PERINEURAL ANALGESIA/MANAGEMENT OF SHOCK
| PERINEURAL ANALGESIA AND CATHETERS —F. Kayser Enneking, MD, Professor of Anesthesiology and Orthopaedics
and Rehabilitation, and Assistant Dean of Clinical Affairs, University of Florida College of Medicine, and Director,
Shands Florida Surgical Center, Gainesville, FL
|
| Introduction: equipment not perfect, but good site-specific analgesia attainable; crucial to know where surgeon will
“trespass” and location of pain; part of multimodal analgesia; patients require fewer narcotics; no special monitoring requirements;
improves patient satisfaction
|
| Review article: Liu (2003) reviewed literature on use of continuous catheters; noted superior analgesia with decreased
incidence of opioid side effects for major surgical procedures; found continuous axillary blocks least efficacious; concluded
that goal was to have controlled-release local anesthetics available; also, that there be benefit beyond analgesia
(speaker disagrees); also noted that need for additional opioids sign of failure of catheter (speaker strongly disagrees)
|
| Evidence: meta-analysis of 17 studies comparing continuous peripheral nerve block (cPNB) analgesia to opioid analgesia;
found that analgesia provided by cPNB superior to that provided by opioids; randomized controlled trials of ropivacaine
vs saline infusion for major wrist and arm surgery with continuous infraclavicular block found low narcotic usage
in patients receiving ropivacaine and higher usage in patients receiving saline infusion; shorter hospital stay
additional benefit of cPNB; caveats—studies conducted in highly selected patient populations; high degree of cooperation
with physical therapists (accelerates recovery)
|
 | Total knee: nighttime sleep quality excellent (important component of recovery; catheters placed on day of surgery and
removed on fourth postoperative day; some patients had some narcotic usage and had highest pain scores after removal
of catheter; controlled-release local anesthetics with 14-day bolus could be helpful; Singelyn looked at use of epidural
vs lumbar plexus vs intravenous (IV) patient-controlled analgesia (PCA); both groups that had regional technique had
improvement in degree of knee flexion immediately after surgery, lasting 10 days; at 3 mo, difference not apparent; at
speaker’s institution, if knee flexion <60% 10 days after surgery, patient returns to operating room (OR) for knee manipulation
procedure; Capdevila conducted study of IV PCA lumbar plexus blocks and epidurals; found femoral nerve
catheters improved outcome
|
| Total shoulder: speaker’s study (retrospective); compared continuous interscalene blocks to IV opioids; with interscalene
blocks, 80% to 100% of physical therapy goals for elevation and external rotation achieved immediately, compared to
only ≈40% of goals in patients receiving IV opioids
|
| Candidates for cPNB: important for patients undergoing immediate rehabilitation and those who are narcotic averse;
speaker does not use technique for minor surgery; important to know patient and surgeon population and be able to use
cPNB judiciously; speaker does not use technique in ambulatory patient who is long-term narcotic user for another indication;
instead, offers single-shot block in conjunction with heavy multimodal analgesia; if catheter required, treat in-
hospital
|
| Stimulating vs nonstimulating catheter: nonstimulating catheters have smooth plastic cannula; stimulating catheters
have insulated catheter with incorporated stimulating wire; high success rates with both techniques; stimulating catheter
results in denser block, probably with less local anesthetic; steeper learning curve for stimulating catheter; avoid
overthreading; complication of knotted catheter directly correlated with length of catheter inserted
|
| Wound catheter vs perineural catheter: when wound catheter placed, visual analog scale (VAS) scores generally
below 8-to-10 range; clearly higher than with perineural catheter; perineural catheter provides sensory and motor block
(not the case with wound infusion); skilled anesthesia provider necessary to place catheter; risk for infection with
perineural catheter similar to that for soft-tissue infection; generally minimized by removing catheter and giving course
of IV antibiotics; new literature suggests problem with bupivacaine administered through catheter for intra-articular use;
role for wound infusion in selected patients; “if you really want to provide good analgesia then you’re better off with a
perineural infusion”
|
| Drug choices: study looked at hand strength and compared continuous interscalene block with either ropivacaine 0.2%
or bupivacaine 0.15%; found that 24 hr after surgery, patients receiving ropivacaine had some impairment of hand
strength; effects wore off over time; impairment less than with bupivacaine; important to note difference in concentration
(unequal potency); another study looked at levobupivacaine 0.125% vs ropivacaine 0.2% and found equivalent motor
block at these doses; with outpatient ambulatory procedure (and even inpatient), patient should be able to participate in
rehabilitation; conclusion—limit motor block; allows for earlier home readiness; may have some role in preventing falls
and pressure ulcers; limit motor block by using dilute local anesthetic infusion, relatively low basal rate (but add generous
patient-controlled bolus), and an electronic pump that delivers consistent level of local anesthetic; low basal rate with
PCA bolus preferred infusion schema; studies indicate greater myonecrosis with bupivacaine
|
| Speaker’s technique: ropivacaine 0.2% or bupivacaine 0.125% solution; low basal rate with PCA function; local anesthetic
placed in catheter initially to establish block (speaker uses mepivacaine); infuse at rate of 4 to 10 mL/hr (most
likely 8 mL/hr with 4-mL bolus every 60 min); consider age and general health status of patient, anticipated pain, and
proximity to nerve; know toxic doses when using higher rates (14-15 mL/hr) or with 2 catheters
|
| Complications: infection common with femoral catheter; psoas compartment block has higher rate of hematoma formation
and rapid local anesthetic uptake; rapid administration may cause vascular channeling and create toxic reaction; few
worries with fascia iliaca compartment block, but less analgesia; popliteal block may have prolonged effect, particularly
in elderly women; with interscalene block, patients complain of shortness of breath when supine; infraclavicular block
may cause chest pain because site of catheter insertion deep muscle; few complications with axillary block, but also provides
less analgesia; neuropathy reported with cPNB, but rate of nerve injury low; localized infection problematic (almost
all reported problems occur with femoral catheter); generally easily treated with removal of catheter and
administration of IV antibiotics; retained catheter more likely to occur when catheter threaded too far; high rate of persistent
paresthesia after shoulder surgery (diabetics at higher risk)
|
| Starting cPNB service: start slowly if unfamiliar with (ie, just learning) cPNB; begin with fascia iliaca compartment
block; then move to nonstimulating femoral catheter, stimulating femoral catheter, and perhaps to psoas compartment
catheter; education of patients, surgeons, physical therapists, and postanesthesia care unit (PACU) nurses important;
speaker places catheters on Mondays and Tuesdays (physical therapy available for entire week) rather than Thursdays
and Fridays; greater time requirement than with single-shot; procedural note, billing sheet, and follow-up note necessary;
institution must decide how to provide coverage; make contact with patient each day and be on phone during catheter removal
|
| ADVANCES IN THE MANAGEMENT OF SHOCK —Ronald Pearl, MD, PhD, Professor and Chair, Department of Anesthesia,
Stanford University School of Medicine, Palo Alto, CA
|
| Definitions of shock: medical definition—condition of profound hemodynamic and metabolic disturbance characterized
by failure of circulatory system to maintain adequate perfusion of vital organs; layperson’s definition—disturbance
in the equilibrium or permanence of something; Gross (19th century physiologist) definition—“a rude unhinging of the
machinery of life”; not simply blood pressure and cardiac output dysfunction, but vital processes stop and fall apart
|
| Hemorrhagic shock: crystalloid resuscitation; transfusion to hematocrit of 30%; hypertonic saline; delayed vs immediate
resuscitation
|
| Cardiac failure: thrombolytic therapy or percutaneous transluminal coronary angioplasty (PTCA) for acute coronary syndrome;
milrinone; brain natriuretic peptide (nesiritide); cardiac resynchronization or biventricular pacing therapy
|
| Septic shock: norepinephrine plus dopamine; vasopressin; steroid-replacement therapy; recombinant human activated
protein C (drotrecogin [Xigris])
|
Hypovolemic–Hemorrhagic Shock
| Timing of resuscitation: hazards of early vigorous resuscitation include increased bleeding, increased coagulopathy, increased
edema, and worsened pulmonary function; Bickell looked at early vs delayed resuscitation in large number of patients
with hypotension due to penetrating chest injury (study design, alternate day); found early resuscitation increased
mortality, hospital length-of-stay, organ failure, transfusions, and coagulopathy
|
| Volume strategies: aggressive fluid resuscitation (to restore intravascular and interstitial fluid volume); fluid restriction
(patients who have metabolic responses to injuries cannot maintain adequate intravascular volume; edema worsens gut function,
wound healing, and myocardial function); study (Arieff)—reported on 13 healthy patients who developed fatal
postoperative pulmonary edema (no underlying medical problems); fatalities related to fluid overload given intraoperatively;
subsequently did survey of various academic medical centers; found postoperative pulmonary edema occurred in >7% of
patients; one-third had no underlying comorbidities predisposing to pulmonary edema; hemodynamic end points (including
central venous pressure) do not predict pulmonary edema; Holte—found 40 mL/kg of lactated Ringer’s solution in healthy
volunteers impairs pulmonary function; multiple studies suggest vigorous fluid resuscitation worsens outcome after surgery;
Nisanevich—randomized patients undergoing abdominal surgery to restricted (4 mL/kg per hour of lactated Ringer’s solution)
or liberal fluids (10 mL/kg bolus, then 12 mL/kg per hour); additional fluid given if urine output low; low-fluid group
had better outcome, fewer complications, decreased time to recovery and bowel movement, and shorter length of stay; evidence
for value of esophageal Doppler proven for patients ventilated in intensive care unit (ICU) and operative patients with
need for intraoperative fluid optimization
|
| Choice of resuscitation fluid: studies of value of hypertonic saline unconvincing; large ongoing study may show
value for prehospital resuscitation
|
| Crystalloid vs colloid controversy: meta-analysis of 19 studies—suggests patients resuscitated with colloid solution have
worse outcome than patients treated with crystalloid solution; subsequent analysis focusing on albumin—suggested
that, compared to crystalloid, albumin increased mortality for hypovolemia, burns, or hypoalbuminemia; other meta-
analyses suggested no harm from colloid; saline vs albumin fluid evaluation (SAFE) study—from Australia and New
Zealand; ≈7000 patients in ICU randomized to 4% albumin or saline; saline group required more fluid (had more positive
fluid balance); hemodynamics identical in both groups; albumin group had increase in serum albumin, saline
group had decrease; mortality, days on mechanical ventilation, and organ failure identical in both groups; small subset
of patients with traumatic brain injury may have had issue with albumin and colloid, but overall, crystalloid and colloid
appear to be identical
|
| Colloid vs colloid controversy: albumin molecular weight 69000; hydroxyethyl starch (eg, Hespan) average weight
450000; colloids may significantly differ; potential for bleeding with hydroxyethyl starch; large molecular weight
molecules decrease factor VIII and von Willebrand factor; recommended limit 20 mL/kg per day
|
| Medium-weight starches: molecular weight range, 130000 to 200000; pentastarch most likely to be used in United
States; no adverse effects on coagulation; may improve vascular permeability, decrease inflammatory response, and
improve microcirculatory flow
|
| Timing of transfusion: classic approach to maintain adequate O2 delivery for O2 consumption; as O2 delivery decreases,
O2 consumption maintained by increasing extraction of O2 from blood; when O2 delivery falls below critical
level, decreased O2 consumption, anaerobic metabolism, and lactic acidosis occur (mixed venous saturation, 50%-60%);
suggests transfusing to maintain level above critical O2 delivery; tolerance of anemia—hemodiluted blood leads to decreased
viscosity; causes increased stroke volume and cardiac output; O2 delivery highest at hematocrit of 30% and normal
at hematocrit of 20%; critical O2 delivery 8 to 10 mL/kg per minute (normally achieved with hemoglobin 4 g/dL and
hematocrit of 12%); Hebert study of restrictive or liberal hemoglobin trigger found all results favored restrictive (7 g/dL)
strategy (decreased hospital and ICU mortality; equal mortality in patients with cardiac disease); study of transfusion
triggers found lower triggers (7 g/dL) resulted in decreased transfusions, no increase in adverse outcomes, and trend toward
decreased mortality
|
Cardiogenic Shock
| Recent advances: mechanical circulatory assist devices; reperfusion after acute myocardial infarction (MI); β-blockers
and angiotensin-converting enzyme inhibitors; cardiac resynchronization therapy; inotropic agents
|
| Cardiac resynchronization therapy (biventricular pacing): based on concept that patient with heart failure develops
conduction abnormalities (particularly left bundle branch block), has disorganized contraction through ventricle,
and, as result, inefficient ejection fraction; meta-analysis of 4 trials showed marked reduction in deaths from heart failure,
hospitalization for heart failure, and trend toward decreased overall mortality; another trial showed improved quality of
life, functional class, and treadmill testing
|
| Inotropic agents: milrinone—type III phosphodiesterase inhibitor; combines inotropic and vasodilator effects; synergistic
effects with catecholamines; effective in patients for weaning off cardiopulmonary bypass, cardiogenic shock, and septic
shock; 20-µg/kg loading dose produces significant inotropic effects; enoximone under development; levosimendan—
investigational; inotropic and vasodilator effects; does not increase mortality with long-term use; however, recent study
showed no change in mortality vs dobutamine (as result, manufacturer not currently seeking approval in United States);
nesiritide—balances arterial and venous vasodilation; decreases right- and left-sided filling pressures; increases cardiac
output; decreases adverse neurohumoral events; increases salt and water excretion; study showed hemodynamic effects similar
to dobutamine but without tachycardia and ventricular ectopy; in another study of decompensated heart failure patients
(randomized to nesiritide, nitroglycerin, or placebo), symptom improvement seen with nesiritide and nitroglycerin; nesiritide
produced greatest decrease in wedge pressure
|
For information on upcoming meetings sponsored by the California Society of Anesthesiologists, visit:
www.csahq.org
Suggested Reading
Arieff AI: Fatal postoperative pulmonary edema: pathogenesis and literature review. Chest 115:1371, 1999; Bickell WH
et al: Immediate versus delayed fluid resuscitation for hypotensive patients with penetrating torso injuries. N Engl J Med
331:1105, 1994; Brandstrup B et al: Danish Study Group on Perioperative Fluid Therapy. Effects of intravenous fluid restriction
on postoperative complications: comparison of two perioperative fluid regimens: a randomized assessor-blinded multicenter
trial. Ann Surg 238:641, 2003; Capdevila X et al: Continuous peripheral nerve blocks in hospital wards after
orthopedic surgery: a multicenter prospective analysis of the quality of postoperative analgesia and complications in 1,416 patients.
Anesthesiology 103:1035, 2005; Casati A et al: Sciatic nerve block with 0.5% levobupivacaine, 0.75% levobupivacaine
or 0.75% ropivacaine: a double-blind, randomized comparison. Eur J Anaesthesiol 22:452, 2005; Enneking FK et
al: Lower-extremity peripheral nerve blockade: essentials of our current understanding. Reg Anesth Pain Med 30:4, 2005;
Finfer S et al: SAFE Study Investigators. A comparison of albumin and saline for fluid resuscitation in the intensive care
unit. N Engl J Med 350:2247, 2004; Hebert PC et al: A multicenter, randomized, controlled clinical trial of transfusion requirements
in critical care. Transfusion Requirements in Critical Care Investigators, Canadian Critical Care Trials Group. N
Engl J Med 340:409, 1999; Erratum in: N Engl J Med 340:1056, 1999; Holte K et al: Liberal versus restrictive fluid management
in knee arthroplasty: a randomized, double-blind study. Anesth Analg 105:465, 2007; Ilfeld BM et al: Ambulatory
continuous interscalene nerve blocks decrease the time to discharge readiness after total shoulder arthroplasty: a
randomized, triple-masked, placebo-controlled study. Anesthesiology 105:999, 2006; Liu SS et al: Effect of postoperative
analgesia on major postoperative complications: a systematic update of the evidence. Anesth Analg 104:689, 2007; Nisanevich
V et al: Effect of intraoperative fluid management on outcome after intraabdominal surgery. Anesthesiology 103:25,
2005; Schierhout G et al: Fluid resuscitation with colloid or crystalloid solutions in critically ill patients: a systematic review
of randomised trials. BMJ 316:961, 1998; Singelyn FJ et al: Effects of intravenous patient-controlled analgesia with
morphine, continuous epidural analgesia, and continuous three-in-one block on postoperative pain and knee rehabilitation after
unilateral total knee arthroplasty. Anesth Analg 87:88, 1998; Wu CL et al: Efficacy of postoperative patient-controlled and
continuous infusion epidural analgesia versus intravenous patient-controlled analgesia with opioids: a meta-analysis. Anesthesiology
103:1079, 2005.
Educational Objectives
| The goals of this program are to increase use of perineural analgesia and catheters for a variety of surgical procedures and to
encourage the adoption of recent advances in the management of shock. After hearing and assimilating this program, the
participant will be better able to:
|
| 1. Review evidence supporting the use of perineural analgesia.
|
| 2. Describe the types of patients who are candidates for continuous peripheral nerve blocks (cPNB).
|
| 3. Determine appropriate drug therapy and catheter techniques for use in cPNB.
|
| 4. List the interventions that may be beneficial for the trauma patient with hemorrhagic shock, cardiac failure, and septic
shock.
|
| 5. Outline management strategies for hypovolemic-hemorrhagic shock and cardiogenic shock.
|
Faculty Disclosure
In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty members to disclose relevant
financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified conflicts
were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial
interest. For this program, the following has been disclosed: Dr. Pearl has received research funding from Ortho-Biotech,
Inc and is a member of the advisory board for Hutchinson Technology, Inc.
Acknowledgments
Dr. Enneking spoke at the 13th Annual Regional Anesthesia and Pain Medicine, held September 29 to October 1,
2006, in Toronto, ON, and sponsored by the University of Toronto Faculty of Medicine, Department of Anesthesia;
Dr. Pearl, at the CSA/ UCSD Annual Meeting and Clinical Anesthesia Update, held May 31 to June 3, 2007, in San
Diego, CA, and cosponsored by the California Society of Anesthesiologists and the University of California, San Diego,
School of Medicine. The Audio-Digest Foundation thanks the speakers and the sponsors for their cooperation in
the production of this program.
|
