Deep parasternal intercostal plane nerve block: an anatomical study

INTRODUCTION

The superficial and deep parasternal intercostal plane (DPIP) blocks are two new blocks for thoracic pain. There are limited cadaveric studies evaluating the dye spread with these blocks. In this study, we examined the dye spread of an ultrasound-guided DPIP block in a human cadaveric model.

METHODS

Five ultrasound-guided DPIP blocks were performed in four unembalmed human cadavers using an in-plane approach with a linear transducer oriented in a transverse plane adjacent to the sternum. Twenty milliliters of 0.1% methylene blue were injected between ribs 3 and 4 into the plane deep to the internal intercostal muscles and superficial to the transversus thoracis muscle layer. The chest muscles were dissected, and the extent of dye spread was documented in both cephalocaudal and mediolateral directions.

RESULTS

The transversus thoracis muscle slips were stained in all cadavers from 4 to 6 levels. Intercostal nerves were dyed in all specimens. Four levels of intercostal nerves were dyed in each specimen with variability in number of levels stained above and below the level of the injection.

CONCLUSIONS

The DPIP block spreads along the tissue plane above the transversus thoracis muscles to multiple levels to dye the intercostal nerves in this cadaver study. This block may be of clinical value for analgesia in anterior thoracic surgical procedures.

Does Preoperative Pharmacogenomic Testing of Patients Undergoing TKA Improve Postoperative Pain? A Randomized Trial

BACKGROUND

Pharmacogenomics is an emerging and affordable tool that may improve postoperative pain control. One challenge to successful pain control is the large interindividual variability among analgesics in their efficacy and adverse drug events. Whether preoperative pharmacogenomic testing is worthwhile for patients undergoing TKA is unclear.

QUESTIONS/PURPOSES

(1) Are the results of preoperative pharmacogenetic testing associated with lower postoperative pain scores as measured by the Overall Benefit of Analgesic Score (OBAS)? (2) Do the results of preoperative pharmacogenomic testing lead to less total opioids given? (3) Do the results of preoperative pharmacogenomic testing lead to changes in opioid prescribing patterns?

METHODS

Participants of this randomized trial were enrolled from September 2018 through December 2021 if they were aged 18 to 80 years and were undergoing primary TKA under general anesthesia. Patients were excluded if they had chronic kidney disease, a history of chronic pain or narcotic use before surgery, or if they were undergoing robotic surgery. Preoperatively, patients completed pharmacogenomic testing (RightMed, OneOME) and a questionnaire and were randomly assigned to the experimental group or control group. Of 99 patients screened, 23 were excluded, one before randomization; 11 allocated patients in each group did not receive their allocated interventions for reasons such as surgery canceled, patients ultimately undergoing spinal anesthesia, and change in surgery plan. Another four patients in each group were excluded from the analysis because they were missing an OBAS report. This left 30 patients for analysis in the control group and 38 patients in the experimental group. The control and experimental groups were similar in age, gender, and race. Pharmacogenomic test results for patients in the experimental group were reviewed before surgery by a pharmacist, who recommended perioperative medications to the clinical team. A pharmacist also assessed for clinically relevant drug-gene interactions and recommended drug and dose selection according to guidelines from the Clinical Pharmacogenomics Implementation Consortium for each patient enrolled in the study. Patients were unaware of their pharmacogenomic results. Pharmacogenomic test results for patients in the control group were not reviewed before surgery; instead, standard perioperative medications were administered in adherence to our institutional care pathways. The OBAS (maximum 28 points) was the primary outcome measure, recorded 24 hours postoperatively. A two-sample t-test was used to compare the mean OBAS between groups. Secondary measures were the mean 24-hour pain score, total morphine milligram equivalent, and frequency of opioid use. Postoperatively, patients were assessed for pain with a VAS (range 0 to 10). Opioid use was recorded preoperatively, intraoperatively, in the postanesthesia care unit, and 24 hours after discharge from the postanesthesia care unit. Changes in perioperative opioid use based on pharmacogenomic testing were recorded, as were changes in prescription patterns for postoperative pain control. Preoperative characteristics were also compared between patients with and without various phenotypes ascertained from pharmacogenomic test results.

RESULTS

The mean OBAS did not differ between groups (mean ± SD 4.7 ± 3.7 in the control group versus 4.2 ± 2.8 in the experimental group, mean difference 0.5 [95% CI -1.1 to 2.1]; p = 0.55). Total opioids given did not differ between groups or at any single perioperative timepoint (preoperative, intraoperative, or postoperative). We found no difference in opioid prescribing pattern. After adjusting for multiple comparisons, no difference was observed between the treatment and control groups in tramadol use (41% versus 71%, proportion difference 0.29 [95% CI 0.05 to 0.53]; nominal p = 0.02; adjusted p > 0.99).

CONCLUSION

Routine use of pharmacogenomic testing for patients undergoing TKA did not lead to better pain control or decreased opioid consumption. Future studies might focus on at-risk populations, such as patients with chronic pain or those undergoing complex, painful surgical procedures, to test whether pharmacogenomic results might be beneficial in certain circumstances.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Evaluating two approaches to the erector spinae plane block: an anatomical study

BACKGROUND AND OBJECTIVES

Studies show variable spread with thoracic erector spinae plane (ESP) injections. Injection sites vary from lateral end of the transverse process (TP) to 3 cm from the spinous process, with many not describing the precise site of injection. This human cadaveric study examined dye spread of ultrasound-guided thoracic ESP block at two needle locations.

METHODS

Ultrasound-guided ESP blocks were performed on unembalmed cadavers. Methylene blue (20 mL, 0.1%) was injected in the ESP at the medial TP at level T5 (medial transverse process injection (MED), n=7) and the lateral end of the TP between T4 and T5 (injection between transverse processes (BTWN), n=7). The back muscles were dissected, and the cephalocaudal and medial-lateral dye spread documented.

RESULTS

Dye spread cephalocaudally from C4-T12 in the MED group and C5-T11 in the BTWN group, and laterally to the iliocostalis muscle in five MED injections and all BTWN injections. One MED injection reached serratus anterior. Dorsal rami were dyed in five MED and all BTWN injections. Dye spread to the dorsal root ganglion and dorsal root in most injections, though more extensively in the BTWN group. The ventral root was dyed in 4 MED and 6 BTWN injections. Epidural spread in BTWN injections ranged from 3 to 12 levels (median: 5 levels), with contralateral spread in two cases and intrathecal spread in five injections. Epidural spread in MED injections was less extensive (median (range): 1 (0-3) levels); two MED injections did not enter the epidural space.

CONCLUSION

An ESP injection administered between TPs exhibits more extensive spread than a medial TP injection in a human cadaveric model.

Evaluating the Anatomic Spread of Selective Nerve Scalp Blocks Using Methylene Blue: A Cadaveric Analysis

BACKGROUND

The modern scalp block consists of local anesthesia injections that target the supraorbital, supratrochlear, zygomaticotemporal, auriculotemporal, and greater and lesser occipital nerves. Limited data exist on the local anesthetic spread that occurs with this technique. This study examines the extent of the spread of a scalp block using methylene blue in a cadaveric model.

METHODS

A traditional landmark-based scalp block was performed on 6 unembalmed human cadavers using 25-G, 1.5-inch needles to inject 1 to 2 mL of methylene blue 0.1% at each nerve bilaterally; a total volume of 20 mL was injected. The cadavers were then dissected, and the spread of injectate was measured and recorded.

RESULTS

All the nerves required for analgesic coverage were appropriately stained by the injections, except for in 2 specimens where the lesser occipital nerve could not be identified. The zygomatic (stained in 2 of 8 specimens) and temporal (stained in 5 of 8 specimens) branches of the facial nerve were stained as a result of the zygomaticotemporal and/or auriculotemporal injections. Tracking from the zygomatic injection site was noted as far inferior as the temporalis muscle attachments on the mandible.

CONCLUSIONS

This cadaveric study confirms that the landmark-based technique for scalp blocks consistently stained all 6 nerves involved in scalp innervation. There was significant unintentional spread to the branches of the facial nerve when using the landmark technique.

Lateral popliteal block in foot and ankle surgery: Comparing ultrasound guidance to nerve stimulation. A prospective randomized trial

BACKGROUND

The popliteal block has several benefits in foot and ankle surgery. It reduces postoperative pain, limits the use of narcotics and facilitates early discharge. The aim of this prospective randomized trial was to evaluate whether ultrasound guidance improves block characteristics compared to the nerve stimulation technique in lateral popliteal blocks.

METHODS

Patients were randomized to receive either a lateral popliteal block using neurostimulation or ultrasound guidance. Block performance time, number of needle pricks, number of redirections were recorded. Pain upon admission to and discharge from post anesthesia care unit (PACU) was recorded. Block duration, patient satisfaction, pain at block site and amount of opioids used in PACU and between subsequent followup visits was recorded. Patients were followed for 12 weeks postoperatively.

RESULTS

There was no statistically significant difference between the two groups in terms of number of pricks, time for the block to wean, pain upon admission to PACU, amount of opioids received in PACU, pain upon discharge from PACU, pain at the operative site, pain at the block site, toe motor function and toe sensation. There was a statistically significant difference in the block procedure performance time between the two groups, with the control group being faster (P<0.0001). A significantly larger number of patients in the control group required more than three needle redirections (P=0.0060).

CONCLUSIONS

The lateral sciatic popliteal block using nerve stimulation had similar block characteristics and patient satisfaction with a significantly faster performance time compared to the ultrasound guided technique.

LEVEL OF EVIDENCE

Level I, prospective randomized study.

Evaluating the spread of costoclavicular brachial plexus block: an anatomical study

BACKGROUND AND OBJECTIVES

The costoclavicular brachial plexus block is performed deep and posterior to the midpoint of the clavicle. There are limited data evaluating the spread of the costoclavicular brachial plexus block. We performed a cadaveric study to evaluate the spread of injectate after a costoclavicular brachial plexus block.

METHODS

Five ultrasound-guided costoclavicular block injections were performed with 20 mL of 0.1% methylene blue. The brachial plexus and its branches were dissected from the level of C4 to the lower axilla. The extent of dye spread was recorded including spread to the phrenic nerve, suprascapular nerve, roots, trunks, divisions, cords and terminal branches of the brachial plexus.

RESULTS

The dye extended cephalad to the level of the cricoid cartilage in two of the five injections; three injections had dye extending 0.75 cm, 1.5 cm and 2 cm caudad to the level of the cricoid cartilage, respectively. The C7, C8 and T1 nerve roots were stained in all injections. The dye did not extend cephalad to the C5 and C6 nerve roots. All trunks, cords and divisions of the brachial plexus were stained, as was the suprascapular nerve. There was no spread of dye to the phrenic nerve in any of the specimens.

CONCLUSIONS

This cadaveric study demonstrates that ultrasound-guided injection in the costoclavicular space spreads cephalad to the brachial plexus in the supraclavicular space, consistently reaching the suprascapular nerve and all trunks and cords of the brachial plexus, while sparing the phrenic nerve.

Evaluating the extent of lumbar erector spinae plane block: an anatomical study

Background and objectives

The erector spinae plane (ESP) block is a relatively new interfascial block technique. Previous cadaveric studies have shown extensive cephalocaudal spread with a single ESP injection at the thoracic level. However, little data exist for lumbar ESP block. The objective of this study was to examine the anatomical spread of dye following an ultrasound-guided lumbar ESP block in a human cadaveric model.

Methods

An ultrasound-guided ESP block was performed in unembalmed human cadavers using an in-plane approach with a curvilinear transducer oriented longitudinally. 20 mL of 0.166% methylene blue was injected into the plane between the distal end of the L4 transverse process and erector spinae muscle bilaterally in four specimens and unilaterally in one specimen (nine ESP blocks in total). The superficial and deep back muscles were dissected, and the extent of dye spread was documented in both cephalocaudal and medial–lateral directions.

Results

There was cephalocaudal spread from L3 to L5 in all specimens with extension to L2 in four specimens. Medial–lateral spread was documented from the multifidus muscle to the lateral edge of the thoracolumbar fascia. There was extensive dye in and around the erector spinae musculature and spread to the dorsal rami in all specimens. There was no dye spread anteriorly into the dorsal root ganglion, ventral rami, or paravertebral space.

Conclusions

A lumbar ESP injection has limited craniocaudal spread compared with injection in the thoracic region. It has consistent spread to dorsal rami, but no anterior spread to ventral rami or paravertebral space.

Fatal diffuse pulmonary fat microemboli following reperfusion in liver transplantation with the use of marginal steatotic allografts

Organ shortage is a major cause of delayed liver transplantation and increased waitlist time. The level of donor steatosis is a significant determinant in organ selection. Scarcity of organs has led some programs to expand their acceptable criteria for the percentage of steatosis. We report two cases of liver transplantation of steatotic donor organs that resulted in mortality within hours from transplantation. Postmortem analysis showed evidence of diffuse pulmonary fat microemboli likely originating from the donor organ, with marked preservation reperfusion injury. The mechanism of diffuse fat microemboli in this setting and possible relationship to other perioperative syndromes (transfusion-related lung injury, acute kidney injury, and postreperfusion syndrome) is discussed.

The utility of live video capture to enhance debriefing following transcatheter aortic valve replacement

Background:

The surgical and procedural specialties are continually evolving their methods to include more complex and technically difficult cases. These cases can be longer and incorporate multiple teams in a different model of operating room synergy. Patients are frequently older, with comorbidities adding to the complexity of these cases. Recording of this environment has become more feasible recently with advancement in video and audio capture systems often used in the simulation realm.

Aims:

We began using live capture to record a new procedure shortly after starting these cases in our institution. This has provided continued assessment and evaluation of live procedures. The goal of this was to improve human factors and situational challenges by review and debriefing.

Setting and Design:

B-Line Medical's LiveCapture video system was used to record successive transcatheter aortic valve replacement (TAVR) procedures in our cardiac catheterization/laboratory. An illustrative case is used to discuss analysis and debriefing of the case using this system.

Results and Conclusions:

An illustrative case is presented that resulted in long-term changes to our approach of these cases. The video capture documented rare events during one of our TAVR procedures. Analysis and debriefing led to definitive changes in our practice. While there are hurdles to the use of this technology in every institution, the role for the ongoing use of video capture, analysis, and debriefing may play an important role in the future of patient safety and human factors analysis in the operating environment.

Using simulation and standardized patients to teach vital skills to pain medicine fellows

INTRODUCTION

Simulation is an evolving aspect of medical education. The role of simulation in training programs is variable, however, in technical specialties such as surgery and anesthesiology its role is quickly becoming a standard part of training programs. Pain fellowship programs must teach clinical diagnostic skills, pharmacology and pathophysiology, in addition to interventional skills to fellows with varying residency backgrounds.

METHODS

The implementation of a hybrid simulation course into the pain fellowship curriculum allows for active learning as fellows experience challenging patient scenarios, stressful periprocedural events, and cases gone awry that require emergency algorithm recall and action.

CONCLUSION

This report describes the incorporation of simulation and crucial conversations into a pain fellowship curriculum.

The Chitranjan Ranawat Award: Periarticular injections and femoral & sciatic blocks provide similar pain relief after TKA: a randomized clinical trial

BACKGROUND

Two of the more common methods of pain management after TKA are peripheral nerve blocks and intraarticular/periarticular injections. However, we are not aware of any study directly comparing the commonly used combination of a continuous femoral block given with a single-shot sciatic block with that of a periarticular injection after TKA.

QUESTIONS/PURPOSES

This randomized clinical trial compared a combined femoral and sciatic nerve block with periarticular injection as part of a multimodal pain protocol after total knee arthroplasty with respect to (1) pain; (2) narcotic use; (3) quadriceps function and length of stay; and (4) peripheral nerve complications.

METHODS

One hundred sixty patients completed randomization into two treatment arms: (1) peripheral nerve blocks (PNB; n=79) with an indwelling femoral nerve catheter and a single shot sciatic block; or (2) periarticular injection (PAI; n=81) using ropivacaine, epinephrine, ketorolac, and morphine. All patients received standardized general anesthesia and oral medications. The primary outcome was postoperative pain, on a 0 to 10 scale, measured on the afternoon of postoperative day 1 (POD 1). Secondary outcomes were narcotic use, quadriceps function, length of stay, and peripheral nerve complications.

RESULTS

Mean pain scores on the afternoon of POD 1 were not different between groups (PNB group: 2.9 [SD 2.4]; PAI group: 3.0 [SD 2.2]; 95% confidence interval, -0.8 to 0.6; p=0.76). Mean pain scores taken at three times points on POD 1 were also similar between groups. Hospital length of stay was shorter for the PAI group (2.44 days [SD 0.65] versus 2.84 days [SD 1.34] for the PNB group; p=0.02). Narcotic consumption was higher the day of surgery for the PAI group (PAI group: 11.7 mg morphine equivalents [SD 13.1]; PNB group: 4.6 mg [SD 9.1]; p<0.001), but thereafter, there was no difference. More patients in the PNB group had sequelae of peripheral nerve injury (mainly dysesthesia) at 6-week followup (nine [12%] versus one [1%]; p=0.009).

CONCLUSIONS

Patients receiving periarticular injections had similar pain scores, shorter lengths of stay, less likelihood of peripheral nerve dysesthesia, but greater narcotic use on the day of surgery compared with patients receiving peripheral nerve blocks. Periarticular injections provide adequate pain relief, are simple to use, and avoid the potential complications associated with nerve blocks.

LEVEL OF EVIDENCE

Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Attributes associated with patient perceived outcome in an academic chronic pain clinic

OBJECTIVES

Patient satisfaction is tied to outcome, but there is scant literature on the relationship of patient perceived outcome and attributes of the pain clinic visit, including the patient interaction with the pain management specialist. The primary purpose of this study is to identify attributes of the patient-provider interaction most strongly associated with patient perceived outcome of their clinic visit. The secondary aim is to correlate patient perceived outcome with patient self-rated overall health.

METHODS

A patient satisfaction survey conducted via phone approximately 3 weeks after the patient's pain clinic visit.

RESULTS

The response rate was 60.2%; 987 patient surveys collected between 2006 and 2010 were used in the analysis. Four factors were significantly associated with the outcome: (1) Explanations by the physician of the patient's condition and treatment, (2) clear instructions regarding post-appointment activities, (3) knowing the patient as a person, and (4) the patient's self-rated health. In terms of the secondary objective, those who answered very good/excellent regarding their self-rated health had an 87% increased odds of better (very good/excellent) outcome of their pain clinic visit (or 1.87 times the odds of better outcome) compared with those who answered poor/fair/good.

CONCLUSIONS

Our results suggest that pain physicians may positively impact patient perceived outcomes of clinic visits by explaining the patient's condition and treatment, providing instructions, and taking the time to understand the patient and their values.

Patient satisfaction in an academic chronic pain clinic

OBJECTIVES

Patient perception of healthcare quality is of growing interest. It has been shown that patient satisfaction is associated with compliance with medical advice and clinical outcome. The 3-fold purpose of this study was to identify which attributes of the patient-physician interaction most strongly correlated with patients' perceptions of provider quality of care, to identify key drivers that move patients' perception of overall provider quality from "very good" to "excellent," and to identify features of the pain clinic experience that were most important to patients but were simultaneously perceived as lacking.

METHODS

Randomized patient satisfaction survey conducted via telephone approximately 3 weeks after the patient's pain clinic visit.

RESULTS

A total of 999 patients participated in the survey over 5 years (estimated response rate 60.2%). Thoroughness, listening, and time spent with the provider were the 3 attributes most strongly associated with the patients' perceptions of provider quality of care, while thoroughness, listening, punctuality, and clear instructions were the drivers of "very good" vs. "excellent" patient perceived overall provider quality. Areas identified for clinic improvement include thoroughness, providing adequate explanations and instructions, and including patient preferences in decision making.

CONCLUSIONS

These results may guide pain clinic physicians as they seek to improve patient perceptions of their care and ultimately patient outcomes.

Refractory headaches due to multilevel thoracic cerebrospinal fluid leaks

BACKGROUND

Spontaneous cerebrospinal fluid leak is a well-documented cause of postural headache. We report a medically refractory headache due to multilevel thoracic cerebrospinal fluid leaks.

CASE REPORT

A 44-year-old male with an acute onset of postural headache failed to respond to bed rest, hydration, and analgesics. Magnetic resonance imaging demonstrated a large cerebrospinal fluid leak centered at the right T4 and left T11 to 12 levels, with bony pathology evident at the lower thoracic level. Lumbar (L4 to 5) and computed tomography guided T4 to 5 level epidural blood patches provided minimal pain relief. Percutaneous epidural fibrin glue injection at T4 followed by a repeat computed tomography guided epidural blood patch led to significant but incomplete symptom relief. Subsequent imaging demonstrated persistent fluid at the T11 to 12 level. Fibrin glue and epidural blood patches at this level reduced but did not eliminate the leak and residual symptoms. Extensive corrective surgery was offered but declined by the patient.

CONCLUSION

Treatment of multifocal cerebrospinal fluid leaks can be challenging, particularly when at least part of the underlying etiology is fixed structural bony pathology.

Effect of exercise on autonomic mechanisms of baroreflex control of heart rate

We tested whether moderate dynamic exercise alters baroreflex control of heart rate (HR) in conscious dogs and whether the autonomic mechanisms mediating arterial baroreflex control of HR differ in the two settings of rest and exercise. Conscious, chronically instrumented dogs were studied during rest and moderate treadmill exercise (6.4 kpm, 10% grade). Sustained changes in mean arterial pressure (MAP) were induced by graded intravenous infusions of phenylephrine and nitroglycerine. Baroreflex HR sensitivity was assessed as the slope of the linear regression between MAP and HR. Responses to increases and decreases in MAP were analyzed separately. Studies were repeated after muscarinic (atropine, 0.2 mg/kg iv) or beta-adrenergic (propranolol, 2.0 mg/kg iv) blockade during rest and exercise. During control experiments both at rest and during exercise, baroreflex changes in HR were greater in response to decreases than to increases in MAP. Experiments performed after separate cardiac autonomic blockade revealed that at rest baroreflex-induced bradycardia occurs via parasympathetic activation but tachycardia occurs via a combined parasympathetic inhibition-sympathetic activation. During exercise, whereas the magnitude of baroreflex responses was unchanged compared with rest, the autonomic mechanisms mediating the baroreflex changes in HR were altered. In this setting, baroreflex tachycardia and bradycardia occur via modulation of both parasympathetic and sympathetic tone.