Is the introduction of another variable to the strength-duration curve necessary in neurostimulation?

INTRODUCTION

Neurostimulation is the process and technology derived from the application of electricity with different parameters to activate or inhibit nerve pathways. Pulse width (Pw) is the duration of each electrical impulse and, along with amplitude (I), determines the total energy charge of the stimulation.

OBJECTIVES

The aim of the study was to test Pw values to find the most adequate pulse widths in rechargeable systems to obtain the largest coverage of the painful area, the most comfortable paresthesia, and the greatest patient satisfaction.

MATERIAL AND METHODS

A study of the parameters was performed, varying Pw while maintaining a fixed frequency at 50 Hz. Data on perception threshold (Tp ), discomfort threshold (Td ), and therapeutic threshold (Tt ) were recorded, applying 14 increasing Pw values ranging from 50 µsec to 1000 µsec. Lastly, the behavior of the therapeutic range (TR), the coverage of the painful area, the subjective patient perception of paresthesia, and the degree of patient satisfaction were assessed.

RESULTS

The findings after analyzing the different thresholds were as follows: When varying the Pw, the differences obtained at each threshold (Tp , Tt , and Td ) were statistically significant (p < 0.05). The differences among the resulting Tp values and among the resulting Tt values were statistically significant when varying Pw from 50 up to 600 µsec (p < 0.05). For Pw levels 600 µsec and up, no differences were observed in these thresholds. In the case of Td , significant differences existed as Pw increased from 50 to 700 µsec (p ≤ 0.05). The coverage increased in a statistically significant way (p < 0.05) from Pw values of 50 µsec to 300 µsec. Good or very good subjective perception was shown at about Pw 300 µsec.

CONCLUSIONS

The patient paresthesia coverage was introduced as an extra variable in the chronaxie-rheobase curve, allowing the adjustment of Pw values for optimal programming. The coverage of the patient against the current chronaxie-rheobase formula will be represented on three axes; an extra axis (z) will appear, multiplying each combination of Pw value and amplitude by the percentage of coverage corresponding to those values. Using this new comparison of chronaxie-rheobase curve vs. coverage, maximum Pw values will be obtained different from those obtained by classic methods.

Invasive techniques for pain management in palliative care: a single center experience

To achieve a successful pain control, interventional techniques are required in approximately 15% of the patients admitted to the Palliative Care Service (PCS).

OBJECTIVES

To evaluate the frequency and effectiveness of the invasive procedures performed in the PCS of our health area. Other matters studied included complications associated with these procedures, the effects on morphine consumption, and functional status, survival rate, as well as the type and location of pain.

METHODS

A descriptive, observational, retrospective study was performed between January 2009 and December 2011. Patients included were considered difficult to manage and required the assistance of the PCS of the University Hospital La Paz (Madrid).

RESULTS

Patients were divided into 3 groups according to the technique used: sympathetic blocks (group S), epidural catheters (group C), and series of plexus, peripheral nerve, or epidural infiltrations (group I). Ninety-four procedures in 45 patients were performed (3.6% of patients admitted by the PCS). The average mean value of pain intensity before and after procedures decreased significantly (8.6 vs. 3.1, respectively, P < 0.01). The need for strong opioids was reduced (275.5 mg/day previously and 212.8 mg/day after the technique, P < 0.01). The overall complication rate was 16%.

CONCLUSION

The analgesic efficacy of these techniques has been adequate in all groups. Patients who required epidural catheters had a higher rate of complications.

[Septic shock due to a community acquired Clostridium difficile infection. A case study and a review of the literature]

The epidemiology of Clostridium difficile infection has changed in the past decade. The incidence rate of community acquired cases has increased in patients with no typical risk factors. We present a patient who was diagnosed with community-acquired Clostridium difficile infection who presented with acute abdominal pain, and subsequently developed acute renal failure and septic shock. We describe the diagnosis, treatment and outcome and brief review of the literature.

Use of tigecycline in critically ill patients with serious nosocomial intra-abdominal infections

Intra-abdominal infection (IAI) is a frequent complication found in surgical intensive care unit (SICU) and continues to be associated with considerable mortality. Tigecycline, the first-in-class glycylcycline has demonstrated a broad spectrum of activity against a wide range of bacteria commonly found in IAI. This observational retrospective study aimed to describe the experience with tigecycline for serious nosocomial IAI in the SICU. Data were collected from 23 consecutive patients admitted to SICU with serious nococomial IAI who had received empirical treatment with tigecycline. In all cases, IAI was diagnosed via emergency surgery. Severe sepsis was found in 56.5% and 43.5% developed septic shock. Oncological disease was the most common comorbidity (60%). The mean Simplified Acute Physiology Score (SAPS) III within 24 hours from IAI diagnosis was 57.5±14.7, and 87% showed a McCabe score >1 (2 or 3). Escherichia coli was the most common pathogen (43.5%), followed by Bacteroides spp. and Streptococcus spp. (30.4%, respectively). All but one patient received tigecycline in combination (95.7%), particularly with fluconazole (52.2%), followed by piperacillin-tazobactam (43.5%). Empirical antibiotic therapy was considered adequate in 95%. The mean duration of treatment was 8.5±4.5 days. A favorable response was achieved in 78%. Failure of the antibiotic therapy was not observed in any patient. None of the patients discontinued tigecycline due to adverse reactions. SICU mortality was 13%, with no deaths attributable to tigecycline. These findings suggest that tigecycline combination therapy is an effective and well tolerated empirical treatment of serious nosocomial IAI in the SICU.

[Iliac artery occlusion balloons for suspected placenta accreta during cesarean section]

Massive obstetric hemorrhage still remains a major cause of maternal mortality and morbidity. The risk factors associated with this pathology must be identified in order to schedule the appropriate delivery with the necessary resources. A case is presented of an iliac artery occlusion with intravascular balloons for suspected placenta accreta during cesarean section. The perioperative treatment, as well as an analysis of the treatment options is described, along with their advantages and disadvantages, from the use of postpartum hemorrhage protocols, blood transfusion and procoagulant factors, and other maneuvers to control bleeding, until the hysterectomy.

[Failed back surgery, spinal cord stimulation and pregnancy: presentation of a case]

Spinal cord stimulation is increasingly used to manage chronic pain syndromes, such as complex regional pain syndrome, chronic back pain, refractory angina pectoris or peripheral vascular diseases, which are unresponsive to other common less aggressive treatment methods. The early use of this technique in the aforementioned diseases makes it suitable in young women of childbearing age and who wish to become pregnant. We report the case of a 33-year-old woman who became pregnant 4 months after having undergone posterior cord stimulation, and we review the approach to this situation and the perioperative management during the perinatal period.

[General anaesthesia and obstetric bleeding in caesarean section. One year's experience in a university hospital]

INTRODUCTION

Obstetric haemorrhage is an important worldwide cause of morbidity and mortality. General anaesthesia for caesarean section is rarely used. Our goal is to analyse the incidence, causes and risk factors associated with general anaesthesia for caesarean section, and the prevalence of obstetric haemorrhage (HO), its risk factors and predictors of post-caesarean HO together with the use of blood in our hospital population.

METHODS

A retrospective study was conducted on all caesarean section discharge reports from PACU in 2008.

RESULTS

General anaesthesia was required in 12.4% of the patients. Epidural catheter failure as a cause of general anaesthesia was infrequent (2.8%) and within the recommended standards.

CONCLUSIONS

The most frequent indications for caesarean section under general anaesthesia included mainly life-threatening emergencies, and the most important risk factors for general anaesthesia, including coagulation disorders, bleeding in the third trimester, foetal distress and severe pre-eclampsia. General anaesthesia is a risk factor for transfusion, as is abruptio placentae, placenta previa and pre-eclampsia.

[Massive obstetric haemorrhage in a patient with placenta percreta]

We present a case of a 38 year-old patient with prenatal diagnosis of placenta praevia. When the elective caesarean began it was found a placenta accreta. In spite of an emergency hysterectomy, embolisation using interventional radiography was needed after a massive obstetric haemorrhage. The post-operative period progressed without incidents.

[Spanish Society of Anaesthesia (SEDAR) guidelines for pre-anaesthesia checking procedures]

We present this document as a guide to preparing a specific institutional pre-anaesthesia checklist, as recommended in the Helsinki declaration on patient safety in anaesthesiology. Also, the recently recommended WHO "safe surgery check-list" includes a check-list for anaesthesia. A working group was established in accordance with the charter of the Spanish Society of Anaesthesiology and Resuscitation (Sociedad Española de Anestesiología y Reanimación [SEDAR]). The new patient safety culture introduced into medicine, and the recommendations of European anaesthesia societies has led us to design and update protocols in order to improve results in this important part of our speciality. We have prepared these recommendations or guidelines using, as examples, updates of pre-anaesthesia check-lists by other American (ASA), British, or Canadian societies of anaesthesia. With that aim, we enlisted the help of anaesthesia ventilator experts and the participation and advice of experienced anaesthesiologists from all parts of Spain. After various corrections and modifications, the document was available at www.sedar.es, so that any anaesthesiologist could propose any correction, or give their opinion. Finally, these guidelines have been approved by the SEDAR Board of Directors, before it was sent for publication in this journal. The aims of this document are to provide: a guideline applicable to all anaesthesia machines, a descriptive pre-anaesthesia check-list that include everything necessary for the anaesthesia procedure, and a resumed check-list to be available in all the anaesthesia machines or other equivalent, but prepared for each institution, which should include anaesthetic equipment and drugs. So, in order to ensure the aims and requirements of the European Board of Anaesthesiology, the European Society of Anaesthesiology, and the WHO are met, each institution should have a protocol for checking equipment and drugs. These guidelines are applicable to any anaesthesia equipment, enabling every institution to develop their own checking protocols, adapted to their anaesthesia machines and their procedures. With the consent of the SEDAR, this group will collaborate with anaesthesia machines providers in order to develop specific checklists for each of their models that will be available at www.sedar.es.

[Candida peritonitis in a haemodynamically stable patient. First choice of antifungal treatment … fluconazole?]

BACKGROUND

Candida peritonitis in postoperative patients is an independent predictor of mortality. Empirical early antifungal therapy should be started in these patients, since according to the results of studies in patients with candidemia, this has an impact on the prognosis. The treatment recommended by clinical practice guidelines in patients with haemodynamic instability are candins, but they do not make explicit recommendations for patients with dysfunction of other organs, or high lactate levels.

CASE REPORT

A case of rescue treatment with anidulafungin in a patient with candidemia and Candida glabrata peritonitis postoperative haemodynamically stable, but with an acute renal failure and elevated plasma lactate, is reported. We discuss the antifungal treatment recommendations established by clinical practice guidelines.

CONCLUSIONS

One conclusion based on this case is that the haemodynamic instability as a marker of severe sepsis must be equated with dysfunction of any organ and/or a plasma lactate level ≥ 2.5 mmol/l in order to advocate candins as an antifungal treatment. In addition, it should be emphasised that anidulafungin was effective in a clinically difficult patient with candidemia and Candida peritonitis, even when used as late rescue antifungal treatment.

Helmet noninvasive mechanical ventilation in patients with acute postoperative respiratory failure

BACKGROUND

The physiological and clinical effects of noninvasive ventilation (NIV) on acute postoperative respiratory failure are relatively unknown. The aim of this study was to determine the prediction factors for failure in the use of NIV with a helmet in this context.

METHODS

This was a prospective observational study. The use of NIV was assessed for a period of 2 years in a postoperative ICU. Demographic data were collected, as well as acute respiratory failure (ARF) and arterial gas readings. Hemodynamic changes were assessed using pulse contour cardiac output technology, and the clinical development of subjects was recorded. All subjects who developed ARF were treated using NIV as their primary care, depending on whether the technique was successful or the subject required intubation. The risk factors that determined failure in the application of NIV were subsequently determined.

RESULTS

Of the 99 subjects presenting with postoperative ARF treated with NIV using a helmet, 74 did not require intubation (74.7%). Following a multivariate analysis using logistic regression, we determined that there are 3 independent risk factors for the failure of NIV. Three factors were associated with respiratory failure: ARDS, pneumonia, and lack of improvement with NIV in 1 hour (increase in the P(aO(2))/F(IO(2))).

CONCLUSIONS

NIV using a helmet could provide an effective alternative to conventional ventilation in selected patients with postoperative ARF.

A randomized control trial of patient-controlled epidural analgesia (PCEA) with and without a background infusion using levobupivacaine and fentanyl

BACKGROUND

Continuous infusion associated with patient-controlled epidural analgesia (PCEA) is used in many maternal units. This randomized controlled study evaluated the effect of a 10 mL/h background infusion associated with a 10 mL-20 minutes lockout time demand-only PCEA protocol using L-bupivacaine plus fentanyl in terms of local anaesthetic consumption, pain management and maternal satisfaction.

METHODS

Forty consenting parturients were randomly assigned to receive a 0.125% levobupivacaine plus 1.5 mcg/mL fentanyl PCEA (10 mL bolus with a 20 min lock time) with or without a 10 mL/h background infusion. The total volume of local anesthetic, the number of PCEA demand boluses, pain levels, delivery outcome and maternal satisfaction were evaluated.

RESULTS

The total volume of local anaesthetic was 35[20-120] mL in demand-only PCEA group versus 63.8[22.5-123] mL in PCEA plus background infusion group (P<0.001). This decrease in total volume was associated with an increase of self-administrated boluses in demand-only group (3.5[2-12] boluses, versus 1[0-3] bolus in PCEA plus background infusion group) (P<0.001). Pain scores were comparable between groups at any time of the study (P>0.05). Maternal satisfaction did not differ between groups (10[8-10] vs. 10[7-10]; P=0.11).

CONCLUSION

When a levobupivacaine plus fentanyl PCEA protocol with high volume boluses and long lockout interval is used for labour analgesia, the background infusion increased the total local anesthetic dose with no change in pain management and maternal satisfaction.

Epigenomic profiling in polycythaemia vera and essential thrombocythaemia shows low levels of aberrant DNA methylation

AIMS

The purpose of this study was to compare the DNA-methylation signature in classic chronic Philadelphia negative myeloproliferative neoplasms (MPN), polycythaemia vera (PV) and essential thrombocythaemia (ET), in order to obtain a global insight into DNA-methylation changes associated with these malignancies.

METHODS

Thirty-five MPN samples from 11 ET JAK2 V617F, 12 ET JAK2 wild type (WT) and 12 PV JAK2 V617F patients as well as 12 from healthy donors were analysed. DNA samples extracted from whole peripheral blood were hybridised to the 'HumanMethylation27 DNA Analysis BeadChip.'

RESULTS

All groups showed a very homogeneous methylation pattern. Only the ZNF577 gene showed a differential methylation profile between PV JAK2 V617F positive and controls. This aberrant methylation was correlated with a differential gene expression of ZNF577. No aberrant hypermethylation was found in the SOCS-1 and SOCS-3 genes.

CONCLUSIONS

According to our results, an aberrant methylation pattern does not seem to play a crucial role in MPN pathogenesis; nor does it justify phenotypical differences between PV and ET.

[Estimating the angle of left lateral decubitus position during cesarean section: observational study of anesthesiologists' estimates and of midwives and nurses' level of understanding]

OBJECTIVES

To determine the difference between the estimated and measured values of the left lateral decubitus (LLD) angle in the positioning of patients for scheduled cesarean section; to determine whether the accuracy of estimates differs between staff anesthesiologists and residents; and to assess the angle estimates of midwives and surgical nurses as well as their level of knowledge with respect to the utility of the LLD position.

METHODS

This was a prospective, observational, double-blind study comparing staff anesthesiologists working in obstetrics to residents in their second, third, or fourth-year of training. We also presented a task and questions to midwives and surgical nurses who assisted during categories 3 and 4 cesarean sections (elective and scheduled procedures) according to the classification system of he National Institute of Clinical Excellence. The anesthesiologist was asked to place the patient in LLD position after onset of anesthesia and to estimate the LLD angle. A second anesthesiologist measured the angle. The midwives and nurses were asked to place a vacant surgical table at approximately 15 degrees; the angle was then measured. Patient variables (weight, height, anesthetic technique) and staff variables (position, understanding of the purpose of the maneuver, estimated DLL angle, and measured angle) were recorded.

RESULTS

Of 55 women who underwent cesarean sections (98.18% under regional anesthesia), 25 were assessed by staff anesthesiologists and 30 by residents. A total of 14 midwives and 10 surgical nurses participated in the surgical table positioning task and answered questions. The mean (SD) DLL angle estimate of the anesthesiologists was 12.4 degrees (3.4 degrees); the mean measured angle was 7.8 degrees (3.1 degrees). The estimates of staff anesthesiologists were significantly more accurate (P < .001). All the midwives understood the reason for using the DLL position in cesarean section, while only 1 nurse (10%) did (P < .05).

CONCLUSION

The DLL position angle is overestimated by resident anesthesiologists and midwives. It seems that the use and understanding of DLL positioning could be improved.