Validation of a novel point-of-care ultrasound method to assess diaphragmatic excursion.

INTRODUCTION: Point-of-care ultrasound can assess diaphragmatic function and rule in or rule out paresis of the diaphragm. While this is a useful bedside tool, established methods have significant limitations. This study explores a new method to assess diaphragmatic motion by measuring the excursion of the uppermost point of the zone of apposition (ZOA) at the mid-axillary line using a high-frequency linear ultrasound probe and compares it with two previously established methods: the assessment of the excursion of the dome of the diaphragm (DOD) and the thickening ratio at the ZOA. METHODS: This is a single-centre, prospective comparative study on elective surgical patients with normal diaphragmatic function. Following research ethics board approval and patient written consent, 75 elective surgical patients with normal diaphragmatic function were evaluated preoperatively. Three ultrasound methods were compared: (1) assessment of the excursion of the DOD using a curvilinear probe through an abdominal window; (2) assessment of the thickening fraction of the ZOA; and (3) assessment of the excursion of the ZOA. The last two methods performed with a linear probe on the lateral aspect of the chest. RESULTS: Seventy-five patients were studied. We found that the evaluation of the excursion of the ZOA was more consistently successful (100% bilaterally) than the evaluation of the excursion of the DOD (98.7% and 34.7% on the right and left sides, respectively). The absolute values of the excursion of the ZOA were greater than and well correlated with the values of the DOD. CONCLUSION: Our preliminary data from this exploratory study suggest that the evaluation of the excursion of the ZOA on the lateral aspect of the chest using a linear probe is consistently successful on both right and left sides. Future studies are needed to establish the distribution of normal values and suggest diagnostic criteria for diaphragmatic paresis or paralysis. TRIAL REGISTRATION NUMBER: NCT03225508.

Evaluating the depth of the epidural space with the use of ultrasound.

BACKGROUND AND OBJECTIVES: The objective of the present study was to evaluate the use of the ultrasound on the determination of the depth of the epidural space. METHODS: Sixty patients were included in this prospective study; the L(3)-L(4) space was initially identified by palpation followed by the ultrasound measuring the depth of the epidural space (PU). After the epidural puncture the measurements o the depth (PA) were recorded. The data underwent descriptive statistics, and the concordance correlation coefficient and Bland-Altman analysis, with 95% confidence interval were calculated. RESULTS: Analysis of concordance between the palpation and ultrasound methods was 86.6%. Mean values of PU obtained were 4.97 +/- 0.51 cm and PA 4.97 +/- 0.71 cm, and Pearson correlation coefficient of 0.66 while Bland-Altman analysis revealed a mean difference of 0.0035 +/- 0.53 cm with 95% confidence interval between -0.228 and 0.221. CONCLUSIONS: The ultrasound is a precise tool to determine the depth of the epidural space.

The attitude of anesthesiologists and anesthesiology residents of the CET/SBA regarding upper and lower limb nerve blocks.

BACKGROUND AND OBJECTIVES: The use of regional blocks especially peripheral nerve blocks (PNB) has been increasing in anesthesiology due to the reduced need to manage the airways, lower cost, and excellent postoperative analgesia. However, its use has restrictions due to the lack of training, that it takes longer to be done, fear of neurological complications, and systemic toxicity. The objective of this study was to measure the attitude of anesthesiologists and anesthesiology residents at Teaching and Training Centers (CET/SBA) regarding PNBs. METHODS: A 25-item questionnaire was developed and it was available, via the Internet and by mail, to those responsible for the 80 CETs, their instructors and residents. RESULTS: Forty-two CETs (52.5%) returned 188 questionnaires, 62 (32%) from anesthesiology residents and 126 (68%) from anesthesiologists. The Cronbach's alpha coefficient of the questionnaire was 0.79. Factor analysis revealed six factors that explain 53% of scores variance: factor 1 - positive attitude, responsible for 18.34% of the variance; factor 2 - training/use, responsible for 11.73% of the variance; factor 3 - negative aspects, responsible for 7.11% of the variance; factor 4 - limiting factors, responsible for 6.39% of the variance; and factor 5 - regional block as a competence differential, responsible for 5.79% of the variance; and factor 6 - respect for the patient, responsible for 5.4% of the variance. CONCLUSIONS: The questionnaire proved to be a reliable tool to measure the attitude regarding regional blocks. Anesthesiologists demonstrated greater interest for patient-related aspects, while the main focus of residents was the acquisition of technical abilities.

Learning curves and mathematical models for interventional ultrasound basic skills.

BACKGROUND: We aimed to construct learning curves and mathematical learning models for ultrasound basic skills: optimizing needle-ultrasound beam alignment and reaching a target inside a phantom. METHODS: Thirty subjects participated in the study. Each subject performed 25 trials. Linear ultrasound probes and a bovine muscular phantom were used. In Experiment 1, subjects tried to insert a needle parallel to the ultrasound beam with full imaging of the needle. For Experiment 2, a segment of tendon was inserted longitudinally into the phantom at a depth of 1 to 1.5 cm. Subjects tried to insert the needle until contacting the tendon. Learning curves were constructed using the cumulative sum (cusum) method. Bush and Mosteller's mathematical learning models were constructed for each skill. RESULTS: Only 30% and 11% of subjects attained proficiency in Experiments 1 and 2, respectively. The predicted average numbers of trials to achieve 95% success rates as estimated from Bush and Mosteller's models were 37 and 109, respectively. CONCLUSIONS: Learning interventional ultrasound basic skills may require a considerable number of trials. Cusum charts revealed that individuals acquire such abilities at variable rates. As skills were assessed in phantoms, our results do not apply to blocks given to real patients.

Ultrasound-guided ileoinguinal and ileohypogastric nerve block associated with general anesthesia. Case report.

BACKGROUND AND OBJECTIVES: Outpatient surgeries are becoming more frequent. Ilioinguinal and iliohypogastric nerve block has been used in postoperative analgesia of patients undergoing outpatient inguinal herniorrhaphy. Ultrasound-guided regional anesthesia increases the accuracy of deposition of the local anesthetic around the nerves. The objective of this report was to present a case of ultrasound-guided ilioinguinal and iliohypogastric nerve block for outpatient inguinal herniorrhaphy. CASE REPORT: A 36-year old male patient, 74 kg, physical status ASA I, was scheduled for inguinal herniorrhaphy. Ultrasound-guided iliohypogastric and ilioinguinal nerve block was accomplished with 0.5% ropivacaine, followed by total intravenous anesthesia. The patient was discharged from the hospital 4 hours after the procedure with a pain score of 3 in the Verbal Analogue Scale. CONCLUSION: Ultrasound-guided iliohypogastric and ilioinguinal nerve block in patients undergoing outpatient inguinal herniorrhaphy can be done as an aid to postoperative analgesia.

Comparison of the plasma levels of 50% enantiomeric excess (S75/R25) 0.5% bupivacaine combined with 1:200,000 epinephrine between the parasacral and infragluteal sciatic nerve blocks.

BACKGROUND AND OBJECTIVES: Local anesthetics (LA) are safe drugs when the proper dose and localization are used. The rate of absorption of the local anesthetic depends on its mass and blood flow at the site of the injection. The objective of this study was to analyze the plasma concentration of 50% enantiomeric excess (S75R25) 0.5% bupivacaine combined with 1:200,000 epinephrine in the parasacral (PS) and infragluteal (IG) sciatic nerve block (SNB). METHODS: Twenty-eight patients scheduled for ankle and foot surgeries were randomly divided into two groups in this prospective study. In Group 1, SNB was performed with IG neurostimulation, while in Group 2 the PS method was used. Both groups received 30 mL of 0.5% bupivacaine (S75/R25) with 1:200,000 epinephrine. Arterial blood samples, 5 mL, were drawn at 0, 15, 30, 60, and 90 minutes after the administration of the LA. High-performance liquid chromatography was used to analyze the serum concentrations. Demographic data of both groups were compared using the Student t test for independent samples and Fisher's Exact test. Bifactorial Analysis of Variance for repeated samples was used for the data concerning the plasma concentrations. RESULTS: Groups 1 and 2 showed no significant demographic differences. The maximal concentration (Cmax) in Group 1 (308 +/- 91 ng.mL(-1)) was obtained in samples number 5 (90 minutes), while in Group 2 (425 +/- 280 ng.mL(-1)) it was obtained in samples number 2 (15 minutes). Cases of systemic toxicity were not observed. CONCLUSIONS: Cmax of 0.5 % bupivacaine (S75/R25) with 1:200,000 in the parasacral approach was higher when compared with the infragluteal SNB.

Ultrasound-guided central venous puncture in an obese patient with cervical adenomegaly.

BACKGROUND AND OBJECTIVES: Classical central venous techniques are based on superficial anatomical references and the knowledge of the vascular anatomy of the area to be punctured. The ultrasound allows direct vision of vascular and perivascular structures, and the needle during the procedure. The objective of this report was to describe an ultrasound-guided central venous catheter placement in an obese patient with adenomegaly. CASE REPORT: This is a 28 years old white male patient, with 1.70 m, weighing 120 kg, with the diagnosis of nodular sclerosis Hodgkin's lymphoma. An ultrasound-guided internal jugular vein catheter placement was requested to the Anesthesiology Department of the Hospital Governador Celso Ramos due to the presence of a supraclavicular node that would hinder the anatomical reference for the puncture in an obese patient. After obtaining the best image, the left internal jugular vein was punctured and a triple lumen catheter was introduced. It was necessary only a single puncture and the catheter was easily introduced; no complications developed during the procedure.

Ultrasound-guided sciatic-femoral block for revision of the amputation stump. Case report.

BACKGROUND AND OBJECTIVES: The use of ultrasound in regional blocks has become increasingly used because its role as facilitator and its efficacy. Direct ultrasound visualization allows the identification of peripheral nerves, independently of the ability of obtaining sensitive or motor stimulation. CASE REPORT: This is the case of a patient who underwent revision of the amputation stump at the knee under ultrasound-guided sciatic-femoral block with 40 mL of 0.5% ropivacaine, promoting complete sensitive blockade and excellent surgical anesthesia. CONCLUSIONS: Ultrasound assistance is capable of amplifying the spectrum of uses of peripheral nerve blocks in surgical interventions on amputated limbs in situations neurostimulation cannot be used.

Ultrasound-guided obturator nerve block: a preliminary report of a case series.

BACKGROUND AND OBJECTIVES: Obturator-nerve block improves analgesia for knee surgery. Traditional techniques rely on surface landmarks, which can be variable and result in excessive performance times and multiple needle passes. The objective of this study was to evaluate a novel ultrasound-guided technique for localizing the obturator nerve. METHODS: A total of 22 patients undergoing anterior cruciate ligament repair had ultrasound-guided obturator-nerve blocks. Needles were directed under real-time ultrasound guidance. Endpoint for injection consisted of identifying contact of the tip of an insulated needle to nerve confirmed by adductor muscles' contraction. Local anesthetic was injected, and block was evaluated within 30 minutes. After that, ultrasound-guided sciatic-femoral blocks were placed for surgical purposes. Data collected included: time required for nerve identification, minimum stimulating current, number of attempts for correct identification, preblock and postblock adductor muscles' strength, sensory-nerve block, and quality of surgical anesthesia. RESULTS: In 91% of cases, the obturator nerve was correctly identified on first attempt within 30 +/- 23 seconds, as a hyperechoic flat or lip-shaped structure with internal hypoechoic dots. Minimal intensity of current to nerve stimulation was 0.30 +/- 0.08 mA. All patients exhibited decreases in adductor strength. Sensory territories were variable, with no cutaneous distribution in 32% of the patients. Small-dose opioid supplementation was required in 14% of the patients, but none required general anesthesia to complete surgery. CONCLUSIONS: These preliminary data suggest that ultrasound-guided obturator-nerve identification and block are technically easy and highly successful.

Ultrasound-guided nerve blocks.

BACKGROUND AND OBJECTIVES: Ultrasound-guided nerve blocks are based on the direct visualization of nerve structures, needle, and adjacent anatomic structures. Thus, it is possible to place the local anesthetic precisely around the nerves and follow its dispersion in real time, obtaining, therefore, more effective blockades, reduced dependency on anatomic references, decreased anesthetic volume, and increased safety. CONTENTS: The aim of this paper was to review the physical mechanisms of image formation, ultrasound anatomy of the neuro axis and of the brachial and lumbosacral plexuses, equipment and materials used in the blockades, settings of the ultrasound equipment to improve the image, planes of visualization of the needles, the techniques, and training in ultrasound-guided nerve blocks. CONCLUSIONS: The steps for a successful regional block include the identification of the exact position of the nerves, the precise localization of the needle, without causing injuries to adjacent structures, and, finally, the careful administration of the local anesthetic close to the nerves. Although neurostimulation is very useful in identifying nerves, it does not fulfill all those requirements. Therefore, it is believed that ultrasound-guided nerve blocks will be the technique of choice in regional anesthesia in a not too distant future.

Effect of an intravenous single dose of ketamine on postoperative pain in tonsillectomy patients.

BACKGROUND: Tonsillectomy has a high incidence of postoperative pain. The aim of the present study was to determine whether the use of low-dose IV ketamine, before the start of surgery or after the end of the operation, would lead to significantly improved pain control after tonsillectomy in pediatric patients. METHODS: Ninety children, 5-7 years old, scheduled for elective tonsillectomy were randomly assigned to one of three groups of 30 patients each; groups I, II and III. Patients in group I received no ketamine. Patients in group II received 0.5 mg x kg(-1) of ketamine before the surgical start and for group III the same dose was given after the operation ended. Postoperative pain was scored by the Oucher scale. Systolic and diastolic pressures and heart rate were recorded perioperatively. Unwanted side effects were recorded by the ward staff personnel on a 24-h study-specific questionnaire. Statistical tests consisted of Student's t-test, chi-square and anova as appropriated. RESULTS: The number of patients complaining of pain was greater in group I compared with patients in groups II and III with a significative statistical difference (P < 0.05). The degree of postoperative pain was significantly higher in patients of group I compared with groups II and III (P < 0.05). Eight patients in group I needed rescue doses of morphine, three for group II and none for group III. In group I, three of eight patients required two doses of morphine during the first 249 h postoperatively. No unwanted side effects were noted. CONCLUSIONS: The use of a single small dose of ketamine in a pediatric population undergoing tonsillectomy could reduce the frequency or even avoid the use of rescue analgesia in the postoperative period independent of whether used before or after the surgical procedure.