Transcript Kinnick_JC_8_04

Todd Kinnick, DO
Journal Club
August 11, 2004
Continuous Perineural Infusions
at Home: Narrowing the Focus
Regional Anesthesia and Pain Medicine
January-February 2004
Chelly/Williams University of Pittsburgh School
of Medicine
Postoperative pain in ambulatory surgery
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Use of “at home” perineural infusions of local
anesthetic
Use has increased because of
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Ambulatory infusion pumps
Reported beneficial outcome after wound infusion of local
anesthetic
Research and individuals experiences in the use of
continuous nerve block techniques for postop analgesia
after major orthopedic surgery
Introduction of Ropivicaine and its preferential sensory
block as well as a safety profile better than bupivacaine
Interscalene perineural ropivacaine infusion: a
comparison of two dosing regimens
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Ropivacaine 0.2% with a perineural infusion at 8
ml/h provides potent analgesia following moderately
painful shoulder surgery
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High basal rate limits infusion duration because of local
anesthetic reservoir
Non electronic pumps are generally restricted to a
maximum of 500ml and pain often extends past 60 hours
Can the basal rate of an interscalene perineural
ropivacaine infusion be decreased by 50% with a
concurrent 200% increase in patient-controlled bolus dose
without compromising infusion benefits in ambulatory
patients
Enrollment
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Unilateral shoulder surgery desiring
interscalene perineural catheter
Be able to understand the possible local
anesthetic related complications, study
protocol and care of catheter and pump
Have a “caretaker” who would remain with
them during the local anesthetic infusion
Exclusion Criteria
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Any contraindication to interscalene nerve block
Any known heart or lung disease
Baseline O2 sats of less than 98% on room air
History of opioid dependence
Allergy to study medications
Current chronic analgesic therapy
Known hepatic or renal insufficiency
Peripheral neuropathy
Morbid obesity
Catheter infusion regimens
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Ropivacaine 0.2%
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Basal infusion 8ml/h and 2ml/h patient controlled
bolus available every 1 hour
Basal infusion of 4ml/h and a patient controlled
bolus dose of 6 ml available every 1 hour
Portable electronic infusion pumps attached
to the 500 ml reservoir
Patient education
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Medication log
Oral analgesic (oxycodone 5/500)
Pair of non sterile gloves
Self addressed and stamped padded
envelope for pump return
Effectiveness of infusion
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Direct
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Indirect
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Average pain
worst pain
Oral analgesic use
Associated sleep disturbances
1650 cumulative hours of infusion data
Nightly questionnaire
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What was the worst
pain you have felt?
While you were resting,
what was the average
pain you have felt?
Did you have difficulty
sleeping last night
because of pain?
Did you awaken last
night because of pain?
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If yes, how many times
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Have you had any fluid
leakage from the
catheter site?
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Would you describe the
leakage as just once in a
while, or nearly
continuously?
How satisfied are you
with your pain control?
Discussion
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Decreasing the basal infusion rate from 8 to 4
ml/h lengthens infusion duration and provides
similar baseline analgesia when patients
supplement their block with large bolus dose
At the expense of an increase in
breakthrough pain incidence and intensity,
sleep disturbances, and a decrease in
analgesia satisfaction
Many unanswered questions
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What is the best local anesthetic solution?
What is the optimal volumes and durations for the
infusions?
What is the functional endpoint when considering
the effectiveness of a post op pain protocol?
Are adjuncts useful for the infusions?
When are the perineural infusion indicated versus
wound infusions or intra articular infusions?
What role will continuous nerve infusions at home
play in a number of orthopedic surgeries being
performed as outpatient procedures (ie. Minimally
invasive joint replacement and hip arthroscopy)
Other questions
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Plan for physical therapy
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What was the surgical technique?
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(ACL vs ankle fusion)
(ACL patellar tendon vs cadaver allograft)
With new surgical technique are previously
inpatient surgeries only becoming outpatient
procedures?
Who will field the phone calls?
Low dose Bupivacaine: a comparison of
hyperbaric and hypobaric solutions for
unilateral spinal anesthesia
Regional Anesthesia and Pain Medicine
January-February 2004
Kaya/Oguz/Aslan/Kadiogullari Ankara, Turkey
Background and Objectives
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Attempting to achieve unilateral spinal
anesthesia for patients undergoing lower limb
orthopedic surgery by using:
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Small doses of local anesthetic solution
Pencil point directional needles
Maintaining lateral decubitus for 15-30 minutes
Hypobaric and hyperbaric bupivacaine
Factors suggested to increase the rate of
unilateral spinal anesthesia
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Lateral decubitus position
Low dose of anesthetic solution
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Total dose of local anesthetic injected into the spinal canal
in the most important factor
(Doses as low as 4-6mg of bupiv for complete knee
arthroscopy or inguinal hernia repair with a unilateral
distribution of spinal block in 60-80% of patients)
Pencil point needles
Low speed of intrathecal injection
Use of directional injection minimizes mixing within
the CSF
Study population
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50 ASA physical status I-II patients aged 1860 years receiving spinal anesthesia for
elective unilateral orthopedic surgery (toe,
foot, and or ankle)
Exclusion Criteria
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Receiving chronic analgesic therapy
Marked back arthrosis or scoliosis
Obesity (BMI < 30)
Diabetes with or without peripheral neuropathy
Mental disturbance
Materials
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26 gauge atraumatic modified pencil point
needle (Atraucan is a double beveled needle)
Hyperbaric Bupivacaine 7.5mg
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Hypobaric Bupivacaine 7.5mg
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1.5 ml (density = 1.026 g/ml) at 0.5 ml/s without
CSF aspiration or barbotage
4.2 ml (density = .997 g/ml) at 0.5 ml/s without
CSF aspiration or barbotage
Lateral position was maintained for 15
minutes
Results
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Hyperbaric
 Unilateral Block in 20 patients (80%) while in the lateral position
which decreased to 17 (68%) once turned supine
Hypobaric
 Unilateral Block in 19 patients (76%) while in the lateral position
which decreased to 6 patients (24%) once turned supine
Hemodynamic changes were similar between the two group
Initially the motor block on the hyperbaric side was greater for the
first 10 minutes but at the end of the operation there was no
difference between the two groups
Regression of the motor block was faster in the hyperbaric group
Results continued
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No patients required GA
Two patients in each group felt some discomfort
during the operations and received 100 mcgs of
fentanyl
One patient in each group required treatment for
hypotension with 250 cc bolus of 0.9 NS
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Followed by Ephedrine 5 mg in each group
One patient in the hypobaric group received 0.5mg
of atropine for bradycardia
None of the patients developed post dural puncture
headache or urinary retention
Advantages of this technique
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Minimal hemodynamic side effects with
higher cardiovascular stability
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Reduces the incidence of clinically relevant
hypotension to nearly 5%
Faster recovery of motor function
Increase patient satisfaction for not being
totally paralyzed
Faster recovery of bladder function
Reduced delay in patient discharge
Cost of these advantages
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Mainly represented by the delay in
preparation time because of the 15 minute
stay in the lateral decubitus position
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Comparing preparation times of either unilateral or
conventional bilateral spinal block with the same
small dose results in only a 5 minute difference
Statistically significant but clinically negligible
What if you placed your spinal in a “block room”?
Preoperative corticosteroids
for reactive airway
Anesthesiology May 2004
Michael Bishop, MD
UW School of Medicine
Reactive Airway Disease
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Low frequency of adverse outcomes
Reversible bronchoconstriction follow
intubation is probably the rule rather than the
exception
Severe bronchospasm seems to be a serious
complication of low but finite incidence
Bronchospasm severe enough to require
treatment is “probably” 1 in 250
Studies--Silvanus et al
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Patients were selected because of airway
obstruction, which was untreated for at least
1 month, and a positive response after two
puffs of albuterol
Included patients whose FEV1 improved by
more that 10% in response to albuterol
Observed mean changes of 20%
the reversibility of obstruction was not only
statistically significant but also clinically
relevant
Study groups
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Three groups
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1. no treatment other than albuterol just before
intubation
2. five days of albuterol prior to intubation
3. five days of corticosteroid plus albuterol prior to
intubation
Results
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Within 1 day both the albuterol and the
albuterol-corticosteroid group had
significantly improved airway resistance
Regardless of whether single-dose albuterol
pre induction or prolonged albuterol treatment
was used most patients experienced
wheezing after intubation
Only one patient receiving corticosteroid in
addition to five days of albuterol experienced
wheezing after intubation
Corticosteroids
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Enhance the bronchodilatory effect of beta2
adrenergic receptor agonists
Direct effect of corticosteroids on smooth
muscle
Increase the number of beta2 adrenergic
receptors and their response to their receptor
agonists
Corticosteroids-continued
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Inhalational steroids are believed to take
weeks to months to attain their full effect
Systemically administered corticoids may
evoke this effect within 48 hours
Methylprednisolone is thought to yield higher
lung parenchymal concentrations than
cortisol and therefore preferred in systemic
asthma treatment
Should every patient with a history of RA
disease receive a pre op trial of steroids
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Recent study from New Zealand found that over
50% of individuals followed from birth to 26 yrs
complained of wheezing at some point and 14.5%
continued to have occasional symptoms
In US, 8% incidence for asthma is often cited
Which patients should we consider for
steroid treatment?
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Need to be realistic and recognize that the
scheduled procedure may drive how
aggressive we are with pre op steroids
Highest risk patient
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Undergo abdominal or thoracic surgery and are at
greatest risk for post op pulmonary complications
Worst pulmonary function
Attempts to improve lung function to personal best
Any reason not to treat patients
aggressively with corticosteroids
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Brief courses do not seem to be associated
with significant effects on wound healing or
infection
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Meta analysis of 51 studies (2,500 patients) found
that a high pre op dose of methylprednisolone of
15-30 mg/kg was not associated with a significant
increase in complication rates
Delay surgery
Many patients find high doses of steroids
somewhat unpleasant
Is there any reason to withhold
beta blockers from high risk
patients with CAD during non
cardiac surgery
Anesthesiology, January 2004
Kertai, Bax, Klein, Poldermans
Erasmus Med Center, Rotterdam, Netherlands
How often are beta blockers underused?
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Schmidt et al, (Arch intern med 2002)
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158 patients undergoing major noncardiac
surgery, of 67 were eligible to receive
perioperative beta blockers only 25 (37%) did so
Survey of Canadian Anesthesiologists
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93% agreed beta blockers were beneficial in
patients with known CAD
57% reported beta blocker use in these patients
34% of the regular users continued taking beta
blockers beyond the early post op period
What may be the reason for withholding
beta blockers?
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May not be effective enough in reducing
perioperative cardiac events
Limited experience with respect to timing and
dosing of perioperative beta blockers
Contraindications to beta blockers
Availability of effective alternative
cardioprotective treatment strategies
“Classic” contraindications
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Severe left ventricular dysfunction,
exacerbation of reactive airway disease,
Insulin dependent diabetes, worsening of
symptoms of PVD
Several investigators have demonstrated that
PBB and long term use of “cardio selective”
beta blockers (bisoprolol, atenolol, or
metoprolol) was well tolerated with no
substantial increase of adverse effects with
these “classic contraindications”
Potential absolute contraindications
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Major AV nodal conduction disease in the
absence of a pacemaker
Severe asthma or strong reactive airway
disease
In such situation, alpha 2 or less invasive
anesthetic and surgical techniques should be
considered
Cardiovascular effects of beta blockade
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Supply and demand variables
reduction in heart rate (increasing diastolic
perfusion time)
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Diastolic time is curvilinearly related to HR,
increasing rapidly below 75 BPM
Reduction in Contractility (reducing O2
demand)
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Via reversal of the Bowditch-Treppe effect
(increasing contractility with increasing HR)
Cardiovascular effects of beta blockers
(continued)
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Little influence on the primary variables
influencing plaque vulnerability
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(lipid accumulation, matrix degradation, etc)
Vulnerable plaques are stabilized through
decreases in sympathetic tone
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Indirectly influence the determinants of shear
stress
Reduce inflammation
Cardiovascular effects of beta blockers
(continued)
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Potent antiarrhythmic effects (especially in
setting of acute ischemia)
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Reduction in circulating free fatty acids via
inhibition of lipolysis may protect against
ventricular fibrillation
Enhanced rate control in atrial dysrhythmias
As a result of these properties of beta blockers, the
intensity of myocardial ischemia is reduce and the
extent of the MI can be decreased
Studies
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Mangano et al
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200 patients atenolol vs placebo in non cardiac surgery
No difference in the incidence of perioperative MI
Long term follow up 10% mortality with atenolol and 21%
mortality with placebo
Poldermans et al
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Bisoprolol and average of 30 days preop with the dose
adjusted to achieve resting HR of 60 BPM
Continued to receive beta blockers for two years
selective beta1 blocker (bisoprolol) reduced cardiac death
and MI in high risk patients for as long as 2 years after
major vascular surgery
Timing, hemodynamic targets and
duration of PBB
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Practice guidelines of the American College of
Cardiology/American Heart Association
Start as soon as the eligibility of a high risk patient
for surgery is confirmed (days to weeks before)
Goal of resting HR of 60 BPM
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This would be most accurately assessed by response to
exercise or adrenergic challenge
Intermediate or high risk who are already receiving
beta blockers need dobutamine stress echo
Alternative cardioprotective treatment
strategies
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Prophylactic coronary revascularization
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Coronary bypass grafting (combined risks of CABG and
noncardiac surgery might exceed the risk of noncardiac
surgery alone)
Angioplasty with coronary stent placement (delay of
surgery of a t least 6 weeks)
Lipid lowering medications
Poldermans et al demonstrated that statin use was
associated with a more than 4 fold reduction of
perioperative mortality in patients undergoing
vascular surgery