Development of a density-tapered capillary gas cell for laser wakefield acceleration

A capillary gas cell for laser wakefield acceleration was developed with the aid of three-dimensional computational fluid dynamics simulations. The gas cell was specially designed to provide upward density tapering in the longitudinal direction, which is expected to suppress the dephasing problem in laser wakefield acceleration by keeping the accelerated electrons in the acceleration phase of the wake wave. The density-tapered capillary gas cell was fabricated by sapphire plates, and its performance characteristics were tested. The capillary gas cell was filled with a few hundred millibars of hydrogen gas, and a Ti:sapphire laser pulse with a peak power of 3.8 TW and a pulse duration of 40 fs (full width at half maximum) was sent through the capillary hole, which has a length of 7 mm and a square cross section of 350 × 350 µm². The laser-produced hydrogen plasma in the capillary hole was then diagnosed two-dimensionally by using a transverse Mach-Zehnder interferometer. The capillary gas cell was found to provide an upward plasma density tapering in the range of 10¹⁸ cm^-3-10¹⁹ cm^-3, which has a potential to enhance the electron beam energy in laser wakefield acceleration experiments.

Massive venous air embolism with bleeding caused by femoral vein injury during total hip arthroplasty: A case report

INTRODUCTION

Venous air embolism (VAE) from vascular injuries, is of rare occurrence but can result in catastrophic complications during total hip arthroplasty (THA). Early recognition and prompt management of vascular injury are required to avoid severe complications. Especially, bleeding is generally associated with profound hypotension in venous injury. We report an unusual complication of venous air embolism induced by femoral vein rupture during THA.

PATIENT CONCERNS

A 54-year-old male patient with a history of old left acetabular fracture was scheduled for THA. We experienced massive bleeding and VAE induced by femoral vein rupture during total hip arthroplasty. The BP suddenly dropped from 100/70 mm Hg to 80/50 mm Hg with massive bleeding. ETCO2 and SaO2 decreased profoundly.

DIAGNOSIS

The VAE was diagnosed by the change in end- tidal CO2 (ETCO2) and change of vital signs, so we performed ABGA and inserted TEE for confirmination.

INTERVENTIONS

For treatment, patient was managed by oxygen therapy, inotropics, vasopressor, transfusion and surgical repair.

OUTCOMES

Upon consulting with a cardiologist, the patient was extubated the next day and was transferred to the general ward and recovered without serious complications. He stayed for 17 days until finally discharged without complications.

CONCLUSION

Preoperative vascular imaging may be recommended in the revisional case of THA or in patients with the history of hip trauma. The monitoring of ETCO2 and TEE might be helpful to recognize VAE earlier and therefore to avoid catastrophic complications through adequate treatment.

Pneumoperitoneum-induced pneumothorax during laparoscopic living donor hepatectomy: a case report

Background

We present a living donor case with an unexpected large-volume pneumothorax diagnosed using lung ultrasound during a laparoscopic hepatectomy for liver transplantation (LT).

Case presentation

A 38-year-old healthy female living donor underwent elective laparoscopic right hepatectomy. The preoperative chest radiography (CXR) and computed tomography images were normal. The surgery was uneventfully performed with tolerable CO₂ insufflation and the head-up position. SpO₂ decreased and airway peak pressure increased abruptly after beginning the surgery. There were no improvements in the SpO₂ or airway pressure despite adjusting the endotracheal tube. Eventually, lung ultrasound was performed to rule out a pneumothorax, and we verified the stratosphere sign as a marker for the pneumothorax. The surgeon was asked to temporarily hold the surgery and cease with the pneumoperitoneum. Portable CXR verified a large right pneumothorax with a small degree of left lung collapse; thus, a chest tube was inserted on the right side. The hemodynamic parameters fully recovered and were stable, and the surgery continued laparoscopically. The surgeon explored the diaphragm and surrounding structures to detect any defects or injuries, but there were no abnormal findings. The postoperative course was uneventful, and a follow-up CXR revealed complete resolution of the two-sided pneumothorax.

Conclusion

This living donor case suggests that a pneumothorax can occur during laparoscopic hepatectomy due to the escape of intraperitoneal CO₂ gas into the pleural cavity. Because missing the chance to identify a pneumothorax early significantly decreases the safety for living donors, point-of-care lung ultrasound may help attending physicians reach the final diagnosis of an intraoperative pneumothorax more rapidly and to plan the treatment more effectively.

Relationship Between Epidural Steroid Dose and Suppression of Hypothalamus-Pituitary-Adrenal Axis

BACKGROUND

The suppression of hypothalamic-pituitary-adrenal (HPA) axis is a common complication associated with epidural steroid injections (ESIs). However, the effect of different doses is unknown.

OBJECTIVES

The primary objective was to compare the differences in the duration of HPA suppression following treatment with different doses of ESI; triamcinolone acetate (TA) 40 mg and TA 20 mg. The secondary objectives were to compare the extent of salivary cortisol (SC) reduction, the incidence of adrenal insufficiency (AI), and the differences in a numeric rating scale (NRS) depending on the varying levels of TA dose used for ESI.

STUDY DESIGN

A double-blind, parallel-group, randomized controlled trial.

SETTING

Pain clinics in a university hospital.

METHODS

The patients were treated with TA epidurally and divided into 2 groups (T20 and T40) depending on the dose of TA (20 mg and 40 mg). The SC concentration was measured before and after ESI to calculate the duration of HPA axis suppression, the extent of SC concentration reduction, and the SC recovery rate. Additionally, NRS and adrenocorticotropic hormone stimulation tests were used.

RESULTS

Thirty patients were analyzed. The T40 group showed longer HPA suppression (19.7 ± 3.1 days) compared with that of the T20 group (8.0 ± 2.4 days). The recovery rate of the T40 group was lower than that of the T20 group (P < 0.015). However, there was no difference in the extent of reduction in SC concentration after ESI, the occurrence of AI, and pain reduction.

LIMITATIONS

There were selection bias and no placebo control.

CONCLUSIONS

Although the difference in pain relief according to the ESI dose is not significant, the HPA suppression is prolonged with a higher dose than a lower dose, and the recovery is slower. Therefore, the time interval between consecutive ESIs should be adjusted depending on the steroid dose to ameliorate the adverse effects of steroids.

Impact of intraoperative zero-balance fluid therapy on the occurrence of acute kidney injury in patients who had undergone colorectal cancer resection within an enhanced recovery after surgery protocol: a propensity score matching analysis

PURPOSE

An enhanced recovery after surgery (ERAS) protocol for colorectal cancer resection encourages perioperative euvolemic status, and zero-balance fluid therapy is recommended for low-risk patients. Recently, several studies have reported concerns of increased acute kidney injury (AKI) in patients within an ERAS protocol. In the present study, we investigated the impact of intraoperative zero-balance fluid therapy within an ERAS protocol on postoperative AKI.

METHODS

Patients who underwent elective surgery for primary colorectal cancer were divided into zero-balance and non-zero-balance fluid therapy groups according to intraoperative fluid amount and balance. After propensity score (PS) matching, 210 patients from each group were selected. Incidences of AKI were compared between the two groups according to the Kidney Disease Improving Global Outcomes criteria. Postoperative kidney functions and surgical outcomes were also compared.

RESULTS

AKI was significantly higher in the zero-balance fluid therapy group compared to the non-zero-balance fluid therapy group (21.4% vs. 13.8%, p = 0.040) in PS-matched patients. The decrease in the estimated glomerular filtration rate on the day of surgery was significantly higher in the zero-balance fluid therapy group (- 5.9 mL/min/1.73 m² vs. - 1.4 mL/min/1.73 m², p = 0.005). There were no differences in general morbidity or mortality rate, although surgery-related complications were more common in the zero-balance group.

CONCLUSIONS

Despite the proven benefits of zero-balance fluid therapy in colorectal ERAS protocols, care should be taken to monitor for postoperative AKI. Further studies regarding the clinical significance of postoperative AKI occurrence and optimised intraoperative fluid therapy are needed in a colorectal ERAS setting.

Continuous suprascapular nerve block compared with single-shot interscalene brachial plexus block for pain control after arthroscopic rotator cuff repair

OBJECTIVES

We compared the analgesic efficacy of a continuous suprascapular nerve block (C-SSNB) and a single-shot interscalene brachial plexus block (S-ISNB) for postoperative pain management in patients undergoing arthroscopic rotator cuff repair.

METHODS

A total of 118 patients undergoing arthroscopic rotator cuff repair were randomly allocated to the S-ISNB or C-SSNB groups. Postoperative pain was assessed using the visual analog scale (VAS) at 1, 2, 6, 12, and 24 h postoperatively. Supplemental analgesic use was recorded as total equianalgesic fentanyl consumption.

RESULTS

The C-SSNB group showed significantly higher VAS scores at 0-1 h and 1-2 h after the surgery than the S-ISNB group (4.9±2.2 versus 2.3±2.2; p<0.0001 and 4.8±2.1 versus 2.4±2.3; p<0.0001, respectively). The C-SSNB group showed significantly lower VAS scores at 6-12 h after the surgery than the S-ISNB group (4.1±1.8 versus. 5.0±2.5; p=0.031). The C-SSNB group required significantly higher doses of total equianalgesic fentanyl in the post-anesthesia care unit than the S-ISNB group (53.66±44.95 versus 5.93±18.25; p<0.0001). Total equianalgesic fentanyl in the ward and total equianalgesic fentanyl throughout the hospital period were similar between the groups (145.99±152.60 versus 206.13±178.79; p=0.052 and 199.72±165.50 versus 212.15±180.09; p=0.697, respectively).

CONCLUSION

C-SSNB was more effective than S-ISNB at 6-12 h after the surgery for postoperative analgesia after arthroscopic rotator cuff repair.

Preventing deoxygenation with high flow nasal cannula oxygen during induction of general anesthesia for rigid bronchoscopy: Two case reports

RATIONALE

Rigid bronchoscopy under general anesthesia enables performing diagnostic and/or therapeutic procedures in the tracheobronchial tree. As most patients undergoing rigid bronchoscopy have moderate to severe respiratory disease or central airway obstruction, the operators often face the risk of hypoxemia when inserting the rigid bronchoscope into the patients' airway. Applying high flow nasal cannula (HFNC) oxygen therapy before the insertion of the bronchoscope allows to maintain high fractional inspired oxygen (FiO2) and thus leading to maximizing apnea time before desaturation.

PATIENT CONCERNS AND DIAGNOSIS

Case 1: A 70-year-old female patient was diagnosed with lung cancer in the left lower lobe and a tracheal mass of about 2.6 cm * 0.8 cm in size.Case 2: A male patient, 77 years old, 55.7 kg and 157.3 cm in height, had been diagnosed with chronic obstructive pulmonary disease, and was scheduled for the bronchoscopic volume reduction surgery upon exacerbation of his symptoms of dyspnea and cough with sputum.

INTERVENTIONS

Preoxygenation was performed with HFNC (Fisher&Paykel Optiflow Thrive, New Zealand) for 3 minutes before the administration of anesthetic medications. The oxygen flow was set at 50 L/min and the FiO2 at 1.0. SpO2 increased to 100%.

OUTCOMES

The HFNC oxygen has shown its effectiveness in safely maintaining the patients' SpO2 during the prolonged apneic period of inserting bronchoscope.

LESSONS

HFNC oxygen is an effective tool in oxygenating the patients during the induction of rigid bronchoscopy, and that it may be a superior alternative to the conventional method of preoxygenation.

Pigmentation in Koreans: study of the differences from caucasians in age, gender and seasonal variations

BACKGROUND

Human skin colour shows variations throughout life, and many extrinsic and intrinsic factors influence melanogenesis. Facultative pigmentation of sun-exposed skin has been suggested to reflect cumulative lifetime ultraviolet (UV) exposure in caucasians. However, pigmentary changes due to various regulatory factors may be different in dark-skinned peoples.

OBJECTIVES

To observe the variations in skin colour due to ageing, gender differences and seasonal changes in Koreans with skin type IV or V.

METHODS

Skin pigmentation was measured at five body sites (buttock, glabella, the V of the neck area, inner arm and dorsal forearm) using skin reflectance spectroscopy in 497 subjects (age range 0-87 years) in winter and 311 subjects (age range 0-84 years) in summer. Among these subjects, 110 were assessed in both seasons. Three independent measurements at each site were done and the average value was used as the pigmentation level.

RESULTS

Constitutive pigmentation of the buttock was highest in the first decade of life. It then decreased during the second decade and this decreased level was maintained after the third decade. In contrast to caucasians, facultative pigmentation and sun exposure index did not increase with ageing. Gender differences were significant at all body sites after the first decade. Seasonal changes were apparent in dorsal forearm pigmentation. Little difference was seen in forehead pigmentation between summer and winter.

CONCLUSIONS

Basal melanogenic regulation might not be different between Asians and caucasians. However, the sun exposure index may not represent lifelong cumulative UV exposure in Koreans. Age-, gender- and season-related characteristics of skin pigmentation in Koreans imply that genetically determined basal skin colour plays an important part in characterizing later responsiveness to UV radiation and sex hormones. Understanding differences between races will be helpful in studying the regulatory mechanisms of melanogenesis.

Genomic cloning and characterization of mitochondrial elongation factor Tu (EF-Tu) gene (tufM) from maize (Zea mays L.)

We have cloned and characterized a mitochondrial elongation factor Tu (EF-Tu) gene (tufM) in maize (Zea mays L.). This maize tufM gene encoded a polypeptide of 452 amino acid residues, consisting of a putative transit peptide of 55 residues and a mature EF-Tu of 397 residues. The coding region was composed of 12 exons and 11 introns that ranged from 76 to 1673bp in length. The deduced amino acid sequence showed 85.9% and 61.2% identity with Arabidopsis mitochondrial EF-Tu and Arabidopsis chloroplast EF-Tu sequence respectively. The transcription initiation site was determined to be 165bp upstream of the AUG initiation codon by primer extension analysis. Southern blot analysis revealed that the cloned EF-Tu gene was encoded by the members of small gene family in maize. Although this gene does not resemble the Arabidopsis nuclear tufA gene, which encodes the plastid EF-Tu, and does not contain sequence elements found in all cyanobacterial and plastid tufA genes, the predicted amino acid sequence includes an N-terminal extension that resembles a mitochondrial targeting sequence, and shares three unique sequence elements with mitochondrial EF-Tu's from Arabidopsis thaliana, Saccharomyces cerevisiae, and Homo sapiens. Therefore, we concluded that this gene encodes the maize mitochondrial EF-Tu.