The Japanese Epidemiologic Study for Perioperative Anaphylaxis, a prospective nationwide study: clinical signs, severity, and therapeutic agents.

BACKGROUND: Diagnosis of perioperative anaphylaxis is difficult because of its non-specific and variable signs and symptoms. Therapeutic agents used to treat anaphylaxis and anaesthesiologist responses also vary depending on the case, which might affect outcomes; however, only a few studies have focused on these factors. METHODS: This prospective study of perioperative anaphylaxis, a part of the Japanese Epidemiologic Study for Perioperative Anaphylaxis, investigated the clinical signs, its severity, therapeutic drugs, epinephrine administration, and anaesthesiologist responses in cases of perioperative anaphylaxis to assess trends and variability. Shock index was used to assess severity of cardiovascular collapse. RESULTS: In 43 patients analysed in this study, cardiovascular signs (88.4%) were the most frequent, followed by skin (81.4%) and respiratory signs (60.5%). The presence of signs increased during the clinical course. The median time from the first signs to diagnosis of anaphylaxis was 10 (5.0-17.8) min. The rates of epinephrine use were 30.2% (unused), 48.8% (i.v.), and 20.9% (i.m.). The median time from diagnosis of anaphylaxis to epinephrine administration was 7 (inter-quartile range: 1.5-8.0) min. Antihistamines and corticosteroids were each used in 69.8% of cases. The worst shock index was higher in patients who received i.v. epinephrine (2.77 [0.90] mean [standard deviation]) than in both no epinephrine use cases (1.35 [0.41]) and i.m. epinephrine cases (1.89 [0.77] (P<0.001]). CONCLUSIONS: The clinical signs and treatments of perioperative anaphylaxis are variable, and the choice regarding epinephrine administration is based on symptom severity. CLINICAL TRIAL REGISTRATION: UMIN000035350.

Protective effects of farnesyltransferase inhibitor on sepsis-induced morphological aberrations of mitochondria in muscle and increased circulating mitochondrial DNA levels in mice.

Sepsis remains a leading cause of mortality in critically ill patients and is characterized by multi-organ dysfunction. Mitochondrial damage has been proposed to be involved in the pathophysiology of sepsis. In addition to metabolic impairments resulting from mitochondrial dysfunction, mitochondrial DNA (mtDNA) causes systemic inflammation as a damage-associated molecular pattern when it is released to the circulation. Metabolic derangements in skeletal muscle are a major complication of sepsis and negatively affects clinical outcomes of septic patients. However, limited knowledge is available about sepsis-induced mitochondrial damage in skeletal muscle. Here, we show that sepsis induced profound abnormalities in cristae structure, rupture of the inner and outer membranes and enlargement of the mitochondria in mouse skeletal muscle in a time-dependent manner, which was associated with increased plasma mtDNA levels. Farnesyltransferase inhibitor, FTI-277, prevented sepsis-induced morphological aberrations of the mitochondria, and blocked the increased plasma mtDNA levels along with improved survival. These results indicate that protein farnesylation plays a role in sepsis-induced damage of the mitochondria in mouse skeletal muscle. Our findings suggest that mitochondrial disintegrity in skeletal muscle may contribute to elevated circulating mtDNA levels in sepsis.

Low-Dose Farnesyltransferase Inhibitor Suppresses HIF-1α and Snail Expression in Triple-Negative Breast Cancer MDA-MB-231 Cells In Vitro.

The aggressiveness of triple-negative breast cancer (TNBC), which lacks estrogen receptor, progesterone receptor and epidermal growth factor receptor 2 (HER2), represents a major challenge in breast cancer. Migratory and self-renewal capabilities are integral components of invasion, metastasis and recurrence of TNBC. Elevated hypoxia-inducible factor-1α (HIF-1α) expression is associated with aggressiveness of cancer. Nonetheless, how HIF-1α expression is regulated and how HIF-1α induces aggressive phenotype are not completely understood in TNBC. The cytotoxic effects of farnesyltransferase (FTase) inhibitors (FTIs) have been studied in cancer and leukemia cells. In contrast, the effect of FTIs on HIF-1α expression has not yet been studied. Here, we show that clinically relevant low-dose FTI, tipifarnib (300 nM), decreased HIF-1α expression, migration and tumorsphere formation in human MDA-MB-231 TNBC cells under a normoxic condition. In contrast, the low-dose FTIs did not inhibit cell growth and activity of the Ras pathway in MDA-MB 231 cells. Tipifarnib-induced decrease in HIF-1α expression was associated with amelioration of the Warburg effect, hypermetabolic state, increases in Snail expression and ATP release, and suppressed E-cadherin expression, major contributors to invasion, metastasis and recurrence of TBNC. These data suggest that FTIs may be capable of ameliorating the aggressive phenotype of TNBC by suppressing the HIF-1α-Snail pathway. J. Cell. Physiol. 232: 192-201, 2017. © 2016 Wiley Periodicals, Inc.

Effect of Cholecalciferol Supplementation on Vitamin D Status and Cathelicidin Levels in Sepsis: A Randomized, Placebo-Controlled Trial.

OBJECTIVES: To compare changes in vitamin D status and cathelicidin (LL-37) levels in septic ICU patients treated with placebo versus cholecalciferol. DESIGN: Randomized, placebo-controlled, trial. SETTING: Medical and surgical ICUs of a single teaching hospital in Boston, MA. PATIENTS: Thirty adult ICU patients. INTERVENTIONS: Placebo (n = 10) versus 200,000 IU cholecalciferol (n = 10) versus 400,000 IU cholecalciferol (n = 10), within 24 hours of new-onset severe sepsis or septic shock. MEASUREMENTS AND MAIN RESULTS: Blood samples were obtained at baseline (day 1) and on days 3, 5, and 7, to assess total 25-hydroxyvitamin D, as well as vitamin D-binding protein and albumin to calculate bioavailable 25-hydroxyvitamin D. Plasma LL-37 and high-sensitivity C-reactive protein levels were also measured. At baseline, median (interquartile range) plasma 25-hydroxyvitamin D was 17 ng/mL (13-22 ng/mL) and peaked by day 5 in both intervention groups. Groups were compared using Kruskal-Wallis tests. Relative to baseline, on day 5, median change in biomarkers for placebo, 200,000 IU cholecalciferol, and 400,000 IU cholecalciferol groups, respectively, were as follows: 1) total 25-hydroxyvitamin D, 3% (-3% to 8%), 49% (30-82%), and 69% (55-106%) (p < 0.001); 2) bioavailable 25-hydroxyvitamin D, 4% (-8% to 7%), 45% (40-70%), and 96% (58-136%) (p < 0.01); and 3) LL-37: -17% (-9% to -23%), 4% (-10% to 14%), and 30% (23-48%) (p = 0.04). Change in high-sensitivity C-reactive protein levels did not differ between groups. A positive correlation was observed between bioavailable 25-hydroxyvitamin D and LL-37 (Spearman ρ = 0.44; p = 0.03) but not for total 25-hydroxyvitamin D and LL-37. CONCLUSIONS: High-dose cholecalciferol supplementation rapidly and safely improves 25-hydroxyvitamin D and bioavailable 25-hydroxyvitamin D levels in patients with severe sepsis or septic shock. Changes in bioavailable 25-hydroxyvitamin D are associated with concomitant increases in circulating LL-37 levels. Larger trials are needed to verify these findings and to assess whether optimizing vitamin D status improves sepsis-related clinical outcomes.

[Utility of brain natriuretic peptide (BNP) to predict outcomes of patients undergoing elective cardiac surgery].

BACKGROUND: We hypothesized that pre-operative BNP levels predict postoperative morbidity and mortality in patients undergoing non-emergent cardiac surgery. METHODS: We retrospectively assessed patients who underwent non-emergent cardiac surgery at our institution regarding major morbidity (prolonged ventilation > 48 hours and prolonged ICU stay > 7 days), and all-cause mortality within 30 days. The cutoff value of BNP for prolonged ventilation was also evaluated. RESULTS: A total of 62 patients with a mean age of 68.7 +/- 12.4 and preoperative BNP value of 391+/- 324 pg x ml(-1) were included. Risk factors for prolonged ventilation were high preoperative BNP and combined procedures. The risk factor for prolonged ICU stay was high preoperative BNP alone. All-cause mortality within 30 days were associated with high preoperative BNP and low intraoperative urine output. A preoperative BNP value (> 259 pg x ml(-1)) provided the optimal BNP cutoff point for prolonged ventilation, and predicted postoperative hemodynamic instability. CONCLUSIONS: Preoperative BNP predicted postoperative morbidity and mortality.

[Usefulness of the guidelines for prevention of perioperative anaphylaxis associated with latex allergy].

BACKGROUND: Anaphylaxis associated with latex allergy is one of the fatal complications during anesthesia. To prevent this complication, we find out latex allergy and high-risk patients by preoperative interview and keep away not only latex allergic patients but high-risk patients from latex allergen in the operating room. In this study, we evaluated the cost-benefit efficiency of our guidelines. METHODS: This is a prospective observational study for six month. We classified the patients undergoing elective operation into three categories: latex allergy (group LA), high-risk of latex allergy (group LH) and control (group C), and we compared the incidence of perioperative anaphylaxis and the cost of using products without latex allergen. RESULTS: A total of 1.291 patients were enrolled in the analysis. Five patients (0.4%) and 206 patients (16.0%) categorized into group LA, and LH respectively. There was no patient diagnosed with anaphylaxis associated with latex allergy during the observation period. We are able to save the cost of 3.5 million yen every year by our method than using products without latex allergen for all cases. CONCLUSIONS: Our guidelines for prevention of perioperative anaphylaxis associated with latex allergy might be efficient from the standpoint of cost-benefit

[Spinal anesthesia using a low dose of isobaric bupivacaine in a patient with pulmonary artery hypertension and mixed obstructive and restrictive lung disease undergoing repeated femoral fracture surgery].

A 75-year-old woman with primary pulmonary hypertension was on medical therapy and ambulatory oxygen inhalation therapy for 7 years. The patient had right femoral fracture and was admitted to our hospital. She had also suffered from asthma for 2 years, and her vital capacity was 1.35 l with forced expiratory volume in 1 second 0.79 l, and with her mean pulmonary artery pressure 60 mmHg. Open reduction and internal fixation were performed under spinal anesthesia using isobaric bupivacaine 6 mg with fentanyl 10 microg, and the patient was discharged on postoperative 31 day with no major complications. One year after the surgery, she had left femoral fracture, and surgery was performed under spinal anesthesia using isobaric bupivacaine 6 mg with fentanyl 10 microg. With its minimal effects on hemodynamics, we speculate that spinal anesthesia using a low dose of isobaric bupivacaine can be a choice for patients with pulmonary hypertension.

[Antibiotic prophylaxis in the operating room].

BACKGROUND: There are growing interests in perioperative preventation of surgical site infection, since the World Health Organization has published surgical safety checklist with the slogan "safe surgery saves lives" in 2008. According to the surgical safety checklist, the surgical team needs to check whether antibiotic prophylaxis has been given within 60 minutes of skin incision. In this study, we investigated whether anesthesiologists in our institution completed the administration of antibiotics before skin incision. METHODS: Anesthetic records of patients who had undergone elective surgery between April to October 2011 were collected. The records were retrospectively analyzed to examine whether administration of antibiotics had been completed before skin incision or not. RESULTS: Although all the anesthesiologists were aware of the necessity of antibiotic prophylaxis, the administration of antibiotics before skin incision was not completed in 22.8% of 880 patients. The administration of antibiotics tended to delay patients receiving general surgery. CONCLUSIONS: Anesthesiologists should have knowledge on the preventation of surgical site infection especially on antibiotic prophylaxis, because it starts in the operating room.

Hereditary Neuropathy with Liability to Pressure Palsy and Vocal Cord Paralysis After Pulmonary Lobectomy: A Case Report.

Hereditary neuropathy with liability to pressure palsy (HNPP) is a rare peripheral neurological disorder that manifests with increased sensitivity to pressure. In people with this disorder, the peripheral nerves are unusually sensitive to pressure. Minor trauma or compression causing paralysis in the extremities is a hallmark of this disorder. Ensuring there is no pressure on the extremities is recommended as a preventive measure. We describe for the first time, postoperative vocal cord paralysis in a patient with HNPP due to left recurrent laryngeal nerve palsy. Anesthesiologists and surgeons should be aware of this possible complication in patients with HNPP.

Ultrasound-Guided Glossopharyngeal Nerve Block for an Awake Intubation in a Patient Predicted to Have a Difficult Airway: A Case Report.

A peripheral nerve block may be used to improve patient tolerance of awake intubation. During an awake intubation, the glossopharyngeal, superior laryngeal, and recurrent laryngeal nerves can mediate discomfort, pain, cough, glottic closure, and gag reflexes. We describe the use of ultrasound-guided superior laryngeal, recurrent laryngeal, and glossopharyngeal nerve blocks to facilitate awake intubation in a patient predicted to have a difficult airway. The glossopharyngeal nerve block was performed via the parapharyngeal space approach targeting the distal glossopharyngeal nerve. This procedure resulted in an uneventful awake intubation.

Airway ultrasound for patients anticipated to have a difficult airway: Perspective for personalized medicine.

Airway ultrasound allows for precise airway evaluation, particularly for assessing the difficult airway and the potential for front of neck access. Many studies have shown that identification of the cricothyroid membrane by airway ultrasound is more accurate than digital palpation. However, no reports to date have provided clinical evidence that ultrasound identification of the cricothyroid membrane increases the success rate of cricothyroidotomy. This is a narrative review which describes patients with difficult airways for whom airway ultrasound may have been useful for clinical decision making. The role of airway ultrasound for the evaluation of difficult airways is summarized and an approach to the use of ultrasound for airway management is proposed. The goal of this review is to present practical applications of airway ultrasound for patients predicted to have a difficult airway and who undergo cricothyroidotomy.

Near-infrared venous imaging may be more useful than ultrasound guidance for novices to obtain difficult peripheral venous access: A crossover simulation study.

BACKGROUND: Difficult peripheral venous access, especially in obese people, is challenging for novices. We conducted a randomized cross-over study to examine whether near-infrared venous imaging or ultrasound guidance is more useful for novice operators to obtain difficult peripheral venous access. METHODS: Medical students were recruited as participants. After receiving basic training using commercial simulators, participants were randomly assigned to obtain simulated venous access using a difficult venous access simulator with near-infrared venous imaging or ultrasound guidance in a randomized cross-over design. A difficult venous access simulator was newly developed with deep and narrow vessels to simulate an obese patient. The primary outcome measure of the study was the first-time success rate (%), and the secondary outcome measures included procedure time (seconds) and the number of 3 consecutive successful attempts, to represent proficiency with the procedure. Pearson chi-square test, the Wilcoxon signed-rank test, and generalized estimating equations were used for statistical analysis. RESULTS: Forty-one medical students with no experience performing peripheral venous access were enrolled in this study. The rate of successful first attempts did not differ between the 2 groups (70% for near-infrared; 65% for ultrasound guidance; P = .64). The duration of the procedure for the first attempt was significantly shorter using near-infrared imaging (median: 14; interquartile range: 12-19) compared to ultrasound guidance (median 46; interquartile range: 26-52; P = .007). The number of attempts until 3 consecutive successes was not significantly different comparing the 2 approaches (near-infrared: 3 (3, 7.25), ultrasound guidance: 3 (3, 6.25), P = .63). CONCLUSION: There was no difference in success rate of first-time attempts or acquiring proficiency for the 2 methods. However, duration of the first attempt was significantly shorter with near-infrared imaging than with ultrasound guidance. Near-infrared imaging may require less training than ultrasound guidance. Near-infrared venous imaging may be useful for novices to obtain difficult peripheral venous access in obese patients.

General anesthesia for cesarean section in a pregnant woman with systemic vascular malformation: a case report.

BACKGROUND: Vascular malformations are composed of morphologically abnormal vascular tissue, and when located in the head and neck region, they can make it difficult to secure the airway during general anesthesia. CASE PRESENTATION: A 28-year-old pregnant woman with vascular malformations in the pharynx was scheduled to undergo a cesarean section, for which spinal anesthesia was initially chosen. However, after magnetic resonance imaging results revealed the presence of multiple vascular malformations in the lumbar multifidus muscles, spinal anesthesia was considered to be of high risk. Thus, the patient was subjected to general anesthesia tracheal intubation under sedation, and the course of the surgery was without complications. CONCLUSIONS: Because the pathophysiology and clinical sequelae of vascular malformations may be involved in complications, thorough presurgical evaluation of the patient's physical condition and careful anesthesia planning should be done.

Farnesysltransferase Inhibitor Prevents Burn Injury-Induced Metabolome Changes in Muscle.

Burn injury remains a significant public health issue worldwide. Metabolic derangements are a major complication of burn injury and negatively affect the clinical outcomes of severely burned patients. These metabolic aberrations include muscle wasting, hypermetabolism, hyperglycemia, hyperlactatemia, insulin resistance, and mitochondrial dysfunction. However, little is known about the impact of burn injury on the metabolome profile in skeletal muscle. We have previously shown that farnesyltransferase inhibitor (FTI) reverses burn injury-induced insulin resistance, mitochondrial dysfunction, and the Warburg effect in mouse skeletal muscle. To evaluate metabolome composition, targeted quantitative analysis was performed using capillary electrophoresis mass spectrometry in mouse skeletal muscle. Principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and hierarchical cluster analysis demonstrated that burn injury induced a global change in metabolome composition. FTI treatment almost completely prevented burn injury-induced alterations in metabolite levels. Pathway analysis revealed that the pathways most affected by burn injury were purine, glutathione, ß-alanine, glycine, serine, and threonine metabolism. Burn injury induced a suppressed oxidized to reduced nicotinamide adenine dinucleotide (NAD+/NADH) ratio as well as oxidative stress and adenosine triphosphate (ATP) depletion, all of which were reversed by FTI. Moreover, our data raise the possibility that burn injury may lead to increased glutaminolysis and reductive carboxylation in mouse skeletal muscle.

Bleeding After Central Venous Catheter Placement in a Patient With Undiagnosed Acquired Hemophilia A: A Case Report.

Acquired hemophilia A is a rare condition caused by autoantibodies against endogenous coagulation factor VIII, which results in spontaneous bleeding. Workup of a patient with difficult hemostasis after removing and placing a central venous catheter led to the diagnosis of acquired hemophilia A. A 64-year-old man was transferred with an intramuscular right thigh mass. Initial biopsy at an outside facility showed degenerated muscle and coagula and he was transferred for incisional biopsy and definitive treatment. The patient had difficult venous access, and a right internal jugular venous catheter was placed. The catheter insertion site showed slow continuous bleeding. Achieving adequate hemostasis after removing the catheter was difficult, and a hematoma formed after the placement of an infraclavicular axillary venous catheter under ultrasound guidance. Coagulation studies revealed a prolonged activated partial thromboplastin time at 96 seconds. The patient was then diagnosed with acquired hemophilia A by enzyme-linked immunosorbent assay using anti-factor VIII antibodies. Even if ultrasound-guided central venous catheterization is performed carefully, bleeding may occur in some patients, suggesting the possibility of coagulopathy. Decision-making for performing central venous catheterization requires extensive knowledge of coagulopathies to understand the causes of bleeding complications.

Use of a photoacoustic needle improves needle tip recognition in a video recording of simulated ultrasound-guided vascular access: A pilot study.

BACKGROUND: We developed a novel photoacoustic needle, which emits ultrasound produced by the photoacoustic effect. This study focused on the most common "pitfall" associated with placement during ultrasound-guided vascular access, which is misidentification of the needle tip. METHODS: The study was conducted as a prospective cohort study using a questionnaire. The authors intentionally created two successful and one failed ultrasound-guided central venous catheterization videos using the photoacoustic needle on a simulator. Each of these three videos was then split into two movies for viewing, one with standard ultrasound images only and the second including the images from the photoacoustic needle, for a total of six movies. RESULTS: Participants who were 18 anesthesiologists, 12 residents, and 10 medical students, watched each of the six movies and completed a survey whether the puncture was successful or not. In the results, there was a significant difference in the percentage of correct answers whether the movie depicted successful or failed puncture with and without the photoacoustic ultrasound (p = 0.0001). CONCLUSION: The novel photoacoustic needle improved the ability to identify the needle tip on recorded videos. It may have efficacy to prevent serious mechanical complication during the ultrasound-guided vascular access in clinical practice.

Risk factors associated with increased incidences of catheter-related bloodstream infection.

We have implemented several preventive measures to reduce central line-associated bloodstream infection (CLABSI) in the general intensive care unit (ICU) of a university hospital in Japan. Here, we analyzed the factors associated with CLABSI in patients with central venous catheter (CVC) insertions and evaluated the effects of our implemented preventive measures. From July 2013 to June 2018, data was collected from the medical records of 1472 patients with 1635 CVC insertions, including age, sex, Acute Physiology and Chronic Health Evaluation II (APACHE II) score, duration of ICU stay, duration of catheter insertion, insertion site, and mechanical ventilation status. During weekly conferences, a surveillance team comprising intensive care and infection control doctors and nurses determined the patients' CLABSI status. The analyzed factors were compared between CLABSI and central line patients without bloodstream infection. Multivariate analysis revealed three factors associated with CLABSI. Adjusted odds ratios with 95% confidence intervals were as follows: duration of ICU stay, 1.032 (1.019-1.044); duration of catheter insertion, 1.041 (1.015-1.066); and APACHE II score, 1.051 (1.000-1.105). The prominent risk factors were associated with the severity of the initial condition and exacerbation of the clinical condition of the patients during their stays in the ICU. Further strategies to reduce CLABSI must be developed.

Bioavailability of Reduced Coenzyme Q10 (Ubiquinol-10) in Burn Patients.

Mitochondrial dysfunction has been implicated in the pathogenesis of inflammation and multi-organ dysfunction in major trauma, including burn injury. Coenzyme Q10 (CoQ10) is a metabolite of the mevalonate pathway and an essential cofactor for the electron transport in the mitochondria. In addition, its reduced form (ubiquinol) functions as an antioxidant. Little is known as to whether oral CoQ10 supplementation effectively increases intracellular CoQ10 levels in humans. To study the bioavailability of CoQ10 supplementation, we conducted a randomized, double-blind, placebo-controlled study of reduced CoQ10 (ubiquinol-10) (1800 mg/day, t.i.d.) in burn patients at a single, tertiary-care hospital. Baseline plasma CoQ10 levels were significantly lower in burn patients than in healthy volunteers, although plasma CoQ10/cholesterol ratio did not differ between the groups. CoQ10 supplementation increased plasma concentrations of total and reduced CoQ10 and total CoQ10 content in peripheral blood mononuclear cells (PBMCs) in burn patients compared with the placebo group. CoQ10 supplementation did not significantly change circulating levels of mitochondrial DNA, inflammatory markers (e.g., interleukins, TNF-α, IFN-γ), or Sequential Organ Failure Assessment (SOFA) scores compared with the placebo group. This study showed that a relatively high dose of reduced CoQ10 supplementation increased the intracellular CoQ10 content in PBMCs as well as plasma concentrations in burn patients.

[Anesthetic management of Jehovah's Witnesses patients undergoing open heart surgery with cardiopulmonary bypass].

BACKGROUND: The anesthetic management of Jehovah's Witnesses (JW) patients undergoing open heart surgery with cardiopulmonary bypass (CPB) is associated with a major risk of anemic hypoxia. METHODS: Fifteen patients from the community of JW underwent open heart surgery. The surgical procedures undertaken were aortic valve replacement in 7 patients, mitral valve plasty or replacement in 5 patients, repair of congenital heart diseases in 2 patients, and removal of left atrial myxoma in one patient. Hemoglobin values, cardiac output, and oxygen delivery (Do2) as well as consumption (Vo2) were evaluated during and after surgery. RESULTS: After CPB, the mean hemoglobin (Hb) value decreased to 8.2 g x dl(-1) from the baseline level of 11.6 g x dl(-1) (P = 0.0007); however, it increased to 10.5 g x dl(-1) at the end of surgery Cardiac index remained unchanged. Oxygen delivery (Do2) decreased after CPB from its baseline level, whereas oxygen consumption remained unchanged. Twenty-four hours after surgery, Do2 recovered to its baseline level because of an increase in cardiac output with the Hb value of 10.7 g x dl(-1) . CONCLUSIONS: The decrease in Hb level is unavoidable in cardiac surgery with CPB in these JW patients. This survey showed that the decrease in Hb level may be compensated by conserved cardiac output avoiding the decrease of Do2 to its critical level when hypoxia occurs.

Photoacoustic needle improves needle tip visibility during deep peripheral nerve block.

We developed a novel technology using the photoacoustic effect that improve needle tip visibility. We evaluated whether this technology improves needle tip visibility when performing a deep peripheral nerve block in a cadaver model. A photoacoustic needle was developed using a conventional echogenic needle with an intraluminal optical fiber. A pulsed laser sends light from a source through the fiber, which is converted to ultrasound at the needle tip using the photoacoustic effect. A nerve block expert performed deep nerve blocks using the photoacoustic needle and the ultrasound views recorded, with or without photoacoustic ultrasound at the needle tip. Needle tip visibility was evaluated by questionnaire (Likert scale 1: very poor, 5: very good) completed by anesthesiologists evaluating recorded images. The score was presented as median [first quartile, third quartile]. Statistical analysis was performed using the Wilcoxon matched-pairs signed rank test. The scores of needle tip visibility with photoacoustic ultrasound from the needle tip (4.3 [4.0, 4.5]) was significantly higher than that without photoacoustic ultrasound (3.5 [3.2, 3.8]) (p < 0.01). Ultrasound emitted at the needle tip using the photoacoustic effect improves needle tip visibility during deep peripheral nerve blocks.Clinical trial number University Hospital Medical Information Network Center Clinical Trials Registration System (UMIN000036974).