Peripheral Nerve Blocks for Upper Leg Amputations
Phase: PHASE4
Conditions: Peripheral Vascular Diseases, Hyperglycaemia (Diabetic), Hypertension, Coronary Artery Disease, Pulmonary Disease, Chronic Obstructive
Sponsor: University of Florida

Protocol #201702402 
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PI version:  03/26/2025 
Protocol 
 
1. Project Title:   
Peripheral nerve blocks for upper leg amputations 
 
2. Investigator(s): 
Principal investigator:   
José R. Soberón, Jr., MD 
 
 
 
 
NF/SG Veterans Health System 
 
 
 
 
Malcom Randall VA Medical Center 
 
 
 
 
Department of Anesthesiology 
 
 
 
 
1601 Archer Road 
 
 
 
 
Gainesville, Florida 32608 
 
 
 
 
Work:  (352) 548-6000, Extension 3581 
 
 
 
 
Pager:  (352) 413-2317 
 
 
 
 
Cellular:  (786) 247-2749 
 
 
 
 
Email:  jose.soberon@va.gov 
 
3. Abstract: 
Above-the-knee amputations are associated with a high mortality rate, ranging from 2.8-
35% postoperatively [1, 2].  The role of anesthetic choice in these patients, particularly 
with regards to mortality, is unknown.  Patients undergoing these procedures are 
typically elderly and fraught with medical comorbidities which commonly include 
peripheral vascular disease, diabetes, hypertension, coronary artery disease, and 
COPD [1-3].     
Peripheral nerve blocks have been beneficial in the treatment of postoperative pain after 
lower extremity amputation, resulting in lower pain scores and analgesia consumption 
[3, 4].  There are case reports and small case series (the largest containing 10 patients) 
detailing the use of peripheral nerve blocks as a primary anesthetic in this high-risk 
patient population [5-8].  The benefits reported include avoidance of intubation, 
mechanical ventilation, and the hemodynamic swings associated with general 
anesthesia as well as excellent pain control postoperatively.  
To the best of my knowledge and search of the existing literature, peripheral nerve 
blocks have not been evaluated prospectively as a primary anesthetic in the setting of 
above-the-knee amputations.  The results of this study may assist clinicians in choosing 
the appropriate anesthetic option for Veterans undergoing this type of surgery.  The 
purpose of this pilot study would be to determine the feasibility of lower extremity nerve 
blocks and sedation for above-the-knee amputations.  The results of this investigation 
may be used to guide future studies regarding the optimal anesthetic technique(s) for 
major lower extremity amputation. 
 
 
 

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4. Background: 
Avoidance of general anesthesia in this high-risk patient population may have additional 
benefits beyond improved postoperative pain scores and analgesic consumption.  The 
current literature is limited when evaluating anesthetic type for major lower extremity 
amputation and typically categorize patients as having received general or regional 
anesthesia.  A major shortcoming of the current literature, however, is the inclusion of 
neuraxial anesthesia, peripheral nerve blocks, or a combination thereof in the regional 
anesthesia category [1, 2].   
According to the latest report from the VA National Surgery Office, an above-the-knee 
amputation has a 5.6% 30-day mortality rate.  It is unknown if these blocks can be 
utilized consistently as a primary anesthetic or if their use may result in a decreased 30-
day mortality. 
 
5. Specific Aims: 
The primary objective will be to evaluate the ability of the femoral, sciatic, lateral femoral 
cutaneous nerve (LFCN), and obturator blocks to provide surgical anesthesia.  Surgical 
anesthesia will be defined as the 
performance of surgery using only 
sedative medications (propofol or 
dexmedetomidine) without the 
need for opioids/analgesic 
agents, local anesthetic 
infiltration, or conversion to 
general anesthesia.  These four 
nerves are the primary 
innervation to the skin and 
musculoskeletal structures of the 
leg. 
Instances of intraoperative 
analgesic administration or 
conversion to general anesthesia 
will be compared. 
Secondary objectives will include 
assessments of block 
performance times, block onset characteristics defined by onset of decreased 
sensorimotor function in nerve distribution of the blocked extremity, postoperative pain 
scores (using a numerical rating scale) and analgesic administration, PACU discharge 
times, patient satisfaction, and 30-day mortality rate.  Adverse events related to the 
anesthetic and surgical techniques will also be recorded. 
 
 
 
 

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6. Research Plan: 
Veterans scheduled for above-the-knee amputation or knee disarticulation will be invited 
to participate in the study.  Peripheral nerve blocks as well as general anesthesia are 
commonly employed anesthetic techniques for these surgical procedures. 
Inclusion criteria  
1. Patients ≥ 18 years of age undergoing above-the-knee amputation or knee 
disarticulation 
2. Ability to understand and provide informed consent 
Exclusion criteria 
1. Patient refusal or inability to provide informed consent 
2. True allergy, not sensitivity, to any of the following substances:   
a. Local anesthetics 
b. Propofol or other sedative agents 
c. General anesthetic agents 
3. Pregnancy 
4. Severe hepatic impairment 
5. Evidence of infection at or near the proposed needle insertion site 
6. Any sensorimotor deficit, whether acute or chronic, as determined by the PI 
7. Chronic use of opioid medication 
8. BMI ≥ 35 
Methods:   
Research related procedure:  Planned statistical analyses 
All analyses for this pilot study will be conducted in JMP Pro 12.0 (SAS Institute, Cary, 
NC). Categorical measures (e.g. block success) will be summarized as percentages 
(%). For continuous measures (e.g. pain scores), normally distributed measures will be 
summarized as means and standard deviations, and non-normally distributed measures 
will be summarized as median with interquartile range. Differences in block success will 
be examined with χ2 tests. Differences in continuous measures will be examined 
through t-tests, with transformation of outcomes as necessary to satisfy assumptions of 
the statistical test. P < 0.05 will be considered statistically significant.  
Sample size justification 
This is a pilot study proposing the assessment of a convenience sample of n=30. We 
calculated the precision in estimation of the incidence of block failure is 10, 15, or 20%, 
assuming power of 80%. An additional six subjects (for a total of 36) will be enrolled in 
the event that subjects discontinue participation in the study before completing all study 
interventions/interactions (either due to adverse event, withdrawal, etc.).  The respective 
width of the 95% CIs for these estimates would be 0.25, 0.28, 0.31.   
Peripheral nerve blocks 
Standard of care:  At the Malcom Randall VA, peripheral nerve blocks and general 
anesthesia are usually administered.  The choice of nerve blocks is usually left up to the 

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anesthesiologist’s preference.  A time out procedure will be performed confirming the 
patient’s identity and the proposed surgical procedure.  The various block sites will be 
cleansed with Chlorohexidine prep solution.  Femoral and sciatic nerve continuous nerve 
catheters are the most commonly performed blocks for patients receiving lower extremity 
amputation.   
Research related procedure:  After administration of intravenous sedation, lateral femoral 
cutaneous and obturator nerve blocks (in addition to the femoral and sciatic catheters) 
will be performed under ultrasound guidance.   
All enrollees will have ultrasound-guided femoral and sciatic nerve blocks placed per 
current practice at the VA.  Single-injection obturator and lateral femoral cutaneous 
nerve blocks will also be performed. 
All nerve blocks will be performed by Dr. José Soberón, who has expertise in ultrasound-
guided regional anesthesia.  Block time will be counted as the time from needle insertion 
until the completion of the injections.  Any inadequate/failed blocks will be recorded.   
Inadequate blocks will have 
analgesic 
supplementation 
conversion 
to 
general 
anesthesia.  After surgery, pain 
scores and side effects will be 
recorded until discharge from 
the recovery room.  The total 
dose of ropivacaine will be 
under 300mg or 3-4 mg/kg. 
Research related procedure:  
Block onset characteristics and 
incidence of adverse events 
will be recorded. 
Standard of care:  The 
Veteran will then be 
transported to the operating room.   
Research related procedure:  Intravenous sedation using propofol or dexmedetomidine 
will be administered.  General anesthetic agents, opioids, and multimodal analgesics 
will be initially avoided so as to not mask an inadequate block.  The administration of 
these agents, as well as conversion to general anesthesia or surgical local anesthetic 
supplementation, will be recorded.  The incidence of block- and procedure-related 
adverse events will be recorded.  
Standard of care:  After surgery, all patients will be transported to the post anesthesia 
care unit (PACU).  The patients will then be discharged to a ward or ICU bed as 
indicated.   
Research related procedure:  Numerical rating scale pain scores (0-10) will be obtained 
upon arrival and recorded hourly until PACU discharge.  Nausea, pruritis, and other side 

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effects will be recorded.  Patients will be called or visited 24-48 hours post procedure to 
inquire about patient satisfaction.  The medical record will be subsequently reviewed to 
assess 30-day mortality and again at the conclusion of subject enrollment.  The planned 
maximum duration of study participation will be approximately 48 hours from the date of 
surgery.  Additionally, data on survival beyond this point may be obtained from 
administrative sources (CPRS) to assess 30-day and long-term mortality.  
7. Possible Discomforts and Risks: 
While peripheral nerve blocks have a long record of safety and efficacy, participants 
may experience the following:  nerve damage, intravascular injection of local anesthetic, 
cardiac arrest, seizure, bleeding/hematoma, infection, pain at the injection site, or 
numbness or tingling (paresthesia).  These events are rare.  Ineffective or failed blocks 
may require administration of analgesic agents or general anesthesia.  
 
8. Possible Benefits: 
Given the high-risk nature of this patient population, surgery performed with nerve 
blocks and sedation may be safer and provide better pain control compared to general 
anesthesia and opioid therapy.  The efficacy and safety of one approach versus the 
other is not known.  The results of this study may be used to guide clinical decisions for 
future patients undergoing above-the-knee amputation or knee disarticulation or to 
guide larger prospective studies. 
 
9. Conflict of Interest: 
None of the investigators have any relevant financial disclosures. 
 
 

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10. References: 
1. Khan SA, Qianyi RL, Liu C, Ng EL, Fook-Chong S, Tan MG. Effect of anaesthetic  
technique on mortality following major lower extremity amputation: a propensity 
score-matched observational study. Anaesthesia. 2013 Jun;68(6):612-20. 
 
2. Moreira CC, Farber A, Kalish JA, Eslami MH, Didato S, Rybin D, Doros G, 
Siracuse JJ. The effect of anesthesia type on major lower extremity amputation 
in functionally impaired elderly patients. J Vasc Surg. 2016 Mar;63(3):696-701. 
 
3. Flaherty J, Horn JL, Derby R. Regional anesthesia for vascular surgery. 
Anesthesiol Clin. 2014 Sep;32(3):639-59. doi: 10.1016/j.anclin.2014.05.002. 
Epub 2014 Jun 25. Review. PubMed PMID: 25113725. 
 
4. Ayling OG, Montbriand J, Jiang J, Ladak S, Love L, Eisenberg N, Katz J, Clarke 
H, Roche-Nagle G. Continuous regional anaesthesia provides effective pain 
management and reduces opioid requirement following major lower limb 
amputation. Eur J Vasc Endovasc Surg. 2014 Nov;48(5):559-64. doi: 
10.1016/j.ejvs.2014.07.002. Epub 2014 Aug 16. PubMed PMID: 25139251. 
 
5. Bech B, Melchiors J, Børglum J, Jensen K. The successful use of peripheral 
nerve blocks for femoral amputation. Acta Anaesthesiol Scand. 2009 
Feb;53(2):257-60. 
 
6. Baddoo H. A preliminary report on the use of peripheral nerve blocks for lower 
limb amputations. Ghana Med J. 2009 Mar;43(1):24-8. 
 
7. Kumar TS, Indu K, Parthasarathy S. Successful Management of above Knee 
Amputation with Combined and Modified Nerve Blocks. Anesth Essays Res. 
2017 Apr-Jun;11(2):520-521. doi: 10.4103/0259-1162.183161. PubMed PMID: 
28663654; PubMed Central PMCID: PMC5490109. 
 
8. Chia N, Low TC, Poon KH. Peripheral nerve blocks for lower limb surgery--a 
choice anaesthetic technique for patients with a recent myocardial infarction? 
Singapore Med J. 2002 Nov;43(11):583-6. Erratum in: Singapore Med J. 2002 
Dec;43(12):604. PubMed PMID: 12680529.