29 de maio de 2013

Artigo recomendado: Anaesthesia for liver transplantation: experience at a teaching hospital

SKY Fung, TWC Hui, AKY Wong, GMY Lei

HKMJ Vol.5 No.1 March 1999;5:27-33

Objective: To assess the anaesthetic aspects of liver transplantation.
Design: Retrospective study.
Setting: University teaching hospital, Hong Kong.
Patients: The first 55 patients who received liver transplantations between 5 October 1991 and 14 June 1997.
Main outcome measures: The anaesthetic technique used; indications for liver transplantation and type of graft transplanted; survival rate; duration of anaesthesia and surgical starting time; intra-operative changes associated with major transfusion; frequency of hypothermia, coagulopathy, and reperfusion; frequency of use of cell saver devices, veno-venous bypass, and a rapid infusion system; and associated complications.
Results: All patients received general anaesthesia with rapid sequence induction. Most adult recipients had cirrhosis from various causes, whereas biliary atresia was the most common condition in the paediatric population. Both cadaveric and living-related liver transplantations were performed, and the overall 1-year survival rate of patients who received a transplantation before June 1996 was 85%. Veno-venous bypass was used in 84% of adults, but in none of the paediatric patients; a cell saver device was used for all adult patients and 92% of paediatric patients. All transplant recipients had acidosis, hypothermia, and hypotension during the operation.
Conclusions: Liver transplantation is no longer experimental. It is the therapeutic option for patients with chronic liver failure. Good anaesthetic support is an essential element of a liver transplantation service.

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24 de maio de 2013

Artigo recomendado: Hepatic Failure


Norma McAvoy, Euan Thomson, Elizabeth S Wilson

ANAESTHESIA AND INTENSIVE CARE MEDICINE 13:4, 2012 Elsevier Ltd. All rights reserved.

ABSTRACT

The incidence of liver disease is increasing in the UK, attributable to a surge in excessive alcohol consumption and obesity. It is therefore not surprising that intensive care units are managing more patients with chronic liver disease. These individuals are often malnourished and can rapidly progress to multi-organ failure, requiring prolonged spells of organ support.

However the spectrum of liver dysfunction encountered in the critical care setting is quite diverse and includes patients with:
  • acute liver failure.
  • decompensation of chronic liver disease and associated complications.
  • impaired liver function secondary to severe systemic illness and its treatment.

In this article we describe the aetiology, investigation, management and prognosis of patients presenting to critical care with severe liver impairment. Transplantation has radically modified the outcome for many patients and early specialist referral should be considered.

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17 de maio de 2013

Artigo recomendado: A practical approach to anaesthesia for paediatric liver transplantation


J Thomas, M McCulloch, W Spearman, T Butt, A Numanoglu
Departments of Paediatric Anaesthesia, Nephrology, Surgery, Medicine, University of Cape Town, South Africa

Southern African Journal of Anaesthesia & Analgesia • March 2006

ABSTRACT
Anaesthesia for paediatric liver transplantation requires meticulous attention to detail, an understanding of the disease process leading up to the need for transplantation, and an awareness of the haematological, biochemical, and multi-organ consequences of this operation. In the past 20 years, significant advances in surgical techniques, organ procurement and preservation, immunosuppression, anaesthetic management and monitoring, and postoperative care in the intensive care unit have contributed to improved outcomes of both the graft and the patient. In more recent years, the use of reduced size and living related organs has increased the donor pool for infants and children. Paediatric liver transplantation in South Africa, up until the present time, has been centered at the Red Cross Children’s Hospital in Cape Town, and survival rates here are comparable with international figures. This paper highlights the preoperative problems which face the anaesthetist, emphasises the importance of good planning and preparation for the intraoperative procedure, simplifies the surgical technique of the operation, and stresses the value of a multidisciplinary approach to the child requiring liver transplantation.

Introduction
The first liver transplant in children was performed by Starzl in Pittsburg, Philadelphia, in 1967. Cyclosporine and steroid therapy were introduced in 1980, after which survival has significantly improved. The first paediatric liver transplant in South Africa was performed at the Red Cross Children’s Hospital in December 1987. Despite limited resources, this transplant program has performed 79 transplants in 76 patients with excellent patient and graft survival figures.
The actual liver transplantation in children is the culmination of a long pre-transplant program. Most paediatric liver transplants are the consequence of liver failure due to biliary atresia, inborn errors of metabolism of liver origin such as alpha1-antitrypsin deficiency, autoimmune disorders, or cirrhosis. Less commonly, an acute event such as mushroom poisoning or an adverse drug reaction may precipitate fulminant liver failure. This latter group of children and their families have very little time to prepare for this life-changing event, compared with those who have had an agonising wait for an appropriate donor. A shortage of donors due to infections with hepatitis B virus and the human immunodeficiency virus contributes to the waiting list mortality and infrequent transplantation.
Anaesthesia for paediatric liver transplantation is a challenging event, and although many anaesthetists will not be involved in the actual operation, a working knowledge of this procedure is important. Many of the survivors may present for surgery unrelated to their transplantation.

Preoperative assessment
Important factors to consider include:
1. The general health of the child. Document the age, weight, and height.
2. Bruising, signs of encephalopathy, and stigmata of liver disease may be present.
3. The cause of the liver failure: is this acute hepatic failure or end-stage liver disease? This will impact on the presence or absence of the consequences of chronic liver failure – varices, and portal hypertension, as well as on the general nutritional status of the child i.e. healthy as opposed to chronically ill. The liver disease should be regarded as fulminant, sub-acute, or chronic.
4. Liver disease may occur as part of well-recognised syndromes such as Alagille’s syndrome, and the child may have other features, especially cardiac, in keeping with that particular syndrome. These need to be identified and documented.
5. Causes of renal dysfunction may be multi-factorial. Polycystic liver disease is associated with polycystic kidneys, and primary oxaluria may present initially with renal calculi. Hepato-renal syndrome, pre-renal azotaemia, and acute tubular necrosis may each be a factor.
6. Hepato-pulmonary or porto-pulmonary disease may result in a child who is oxygen-dependent. It is advisable that these children have a cardiac echo prior to surgery to assess heart function and the degree of pulmonary hypertension. A cardiac catheterisation may also be necessary. Pre-existing right to left shunts in the pulmonary vascular bed increase the risk of intraoperative systemic air emboli at the time of venous anastomosis. Preoperative hypoxaemia may be due to intrapulmonary arteriovenous shunting, ventilation-perfusion mismatch, restrictive lung disease from ascites and raised intraabdominal pressure, and a decreased pulmonary diffusing capacity. The oxygen dissociation curve is shifted to the right.
7. A hyperdynamic circulation is usually present, with an increased heart rate, cardiac output, and stroke volume, but a decreased systemic peripheral vascular resistance, and low blood pressure.
8. Arteriovenous shunts may be present, which result in increased venous saturations and a decreased arteriovenous difference in oxygen content. These patients are prone to supraventricular tachycardias, cardiomyopathies, valvular lesions (Alagilles), and occasionally biventricular failure. They are often anaemic preoperatively, especially if they have associated renal disease and/or bleeding varices.
9. Presence of varices: gastric, oesophageal, abdominal wall, or rectal. The date of the most recent sclerotherapy should be documented, as well as the date and type of the antibiotics most recently given.
10. Previous surgery. Has the child had previous abdominal surgery such as a Kasai portoenterostomy for biliary atresia or shunts for control of varices. If so, when was the surgery performed? This will impact on the complexity of the surgery, the amount of bleeding encountered in the pre-anhepatic phase, and the length of time before the diseased liver is removed.
11. Document any allergies, as well as the details of previous anaesthetics the child has had. The size of the endotracheal tube last used may be useful in the planning for the anaesthetic.
12. Most of these children have had an appropriate time for starvation before surgery starts, so are usually nil by mouth.
13. Confirm that blood bank and the haematology and biochemistry laboratories have been informed about the operation.
14. Plan for postoperative care; alert the Intensive Care Unit that the child will return to them after surgery.

Investigations
• Blood results required include a full blood count for haemoglobin, platelets, and white cell count, INR, clotting profile with fibrinogen and PTT. An arterial blood gas is not usually necessary and is a painful procedure, so only request this if it forms a useful baseline for management.
Electrolytes are important, especially if there is concomitant renal disease, and calcium, phosphate and magnesium levels should be available. These patients may be alkalotic with low sodium, potassium, calcium, magnesium, and glucose measurements, and may be hyperphosphataemic.
Acidosis usually reflects poor perfusion, liver necrosis, orrenal tubular acidosis.
• Liver function tests results, especially albumin, should be documented. Low albumin may result in poor drug binding, ascites, and a low colloid oncotic pressure.
• Renal function: urea and creatinine levels are necessary.
• Baseline cytomegalovirus and Epstein Barr virus status is required.
• Blood cultures are performed in these children prior to transplantation.
• A chest X ray (CXR) is necessary to identify fluid overload, infection, and to exclude tuberculosis.
• Echo cardiography will be required for the patient who has hepato-pulmonary syndrome and/or pulmonary hypertension.

Preoperative medication
These drugs are usually administered under the instruction of the liver transplant medical team as per program for each individual child. In general this would include:
1. Tacrolimus 0.2mg/kg per os (po), or Cyclosporine 5mg/kg po. The choice of drugs will depend on the current regimen.
2. Mycostatin 2-5 mls per os stat (depending on the child’s age).
3. Glycerine suppositories: 1 per rectum stat.
4. Depending on the coagulation status, a preoperative fresh frozen plasma infusion may be necessary.

Premedication
Anxiolysis is generally all that these children require, and oral midazolam 0.25-0.5 mg/kg half an hour preoperatively is satisfactory. If the child has hepato-pulmonary syndrome with significant shunts and is cyanosed, supplemental oxygen via face mask or nasal cannulae preoperatively is advised.

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14 de maio de 2013

Artigo recomendado: Perioperative Comparative Effectiveness of Anesthetic Technique in Orthopedic Patients


Stavros G. Memtsoudis, Xuming Sun, Ya-Lin Chiu, Ottokar Stundner, Spencer S. Liu, Samprit Banerjee, Madhu Mazumdar, Nigel E. Sharrock

Anesthesiology 2013; 118:1046-58, Memtsoudis et al.

ABSTRACT

Background: The impact of anesthetic technique on perioperative outcomes remains controversial. We studied a large national sample of primary joint arthroplasty recipients and hypothesized that neuraxial anesthesia favorably influences perioperative outcomes.

Methods: Data from approximately 400 hospitals between 2006 and 2010 were accessed. Patients who underwent primary hip or knee arthroplasty were identified and subgrouped by anesthesia technique: general, neuraxial, and combined neuraxial–general. Demographics, postoperative complications, 30-day mortality, length of stay, and patient cost were analyzed and compared. Multivariable analyses were conducted to identify the independent impact of choice of anesthetic on outcomes.

Results: Of 528,495 entries of patients undergoing primary hip or knee arthroplasty, information on anesthesia type was available for 382,236 (71.4%) records. Eleven percent were performed under neuraxial, 14.2% under combined neuraxial–general, and 74.8% under general anesthesia. Average age and comorbidity burden differed modestly between groups. When neuraxial anesthesia was used, 30-day mortality was significantly lower (0.10, 0.10, and 0.18%; P < 0.001), as was the incidence of prolonged (>75th percentile) length of stay, increased cost, and in-hospital complications. In the multivariable regression, neuraxial anesthesia was associated with the most favorable complication risk profile. Thirty-day mortality remained significantly higher in the general compared with the neuraxial or neuraxial–general group for total knee arthroplasty (adjusted odds ratio [OR] of 1.83, 95% CI 1.08–3.1, P = 0.02; OR of 1.70, 95% CI 1.06–2.74, P = 0.02, respectively).

Conclusions: The utilization of neuraxial versus general anesthesia for primary joint arthroplasty is associated with superior perioperative outcomes. More research is needed to study potential mechanisms for these findings.

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9 de maio de 2013

Artigo recomendado: Impact of the Prone Position in an Animal Model of Unilateral Bacterial Pneumonia Undergoing Mechanical Ventilation

Sylvain Ladoire, Laure-Anne Pauchard, Saber-Davide Barbar, Pierre Tissieres, Delphine Croisier-Bertin, Pierre-Emmanuel Charles

Anesthesiology 2013; 118:1150-9, Ladoire et al.

ABSTRACT
Background: The prone position (PP) has proven beneficial in patients with severe lung injury subjected to mechanical ventilation (MV), especially in those with lobar involvement. We assessed the impact of PP on unilateral pneumonia in rabbits subjected to MV.

Methods: After endobronchial challenge with Enterobacter aerogenes, adult rabbits were subjected to either “adverse” (peak inspiratory pressure = 30 cm H2O, zero end-expiratory pressure; n = 10) or “protective” (tidal volume = 8 ml/kg, 5 cm H2O positive end-expiratory pressure; n = 10) MV and then randomly kept supine or turned to the PP. Pneumonia was assessed 8 h later. Data are presented as median (interquartile range).

Results: Compared with the supine position, PP was associated with significantly lower bacterial concentrations within the infected lung, even if a “protective” MV was applied (5.93 [0.34] vs. 6.66 [0.86] log10 cfu/g, respectively; P = 0.008). Bacterial concentrations in the spleen were also decreased by the PP if the “adverse” MV was used (3.62 [1.74] vs. 6.55 [3.67] log10 cfu/g, respectively; P = 0.038). In addition, the noninfected lung was less severely injured in the PP group. Finally, lung and systemic inflammation as assessed through interleukin-8 and tumor necrosis factor-α measurement was attenuated by the PP.

Conclusions: The PP could be protective if the host is subjected to MV and unilateral bacterial pneumonia. It improves lung injury even if it is utilized after lung injury has occurred and nonprotective ventilation has been administered.

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7 de maio de 2013

Artigo recomendado: Magnetic Resonance Imaging Analysis of the Spread of Local Anesthetic Solution after Ultrasound-guided Lateral Thoracic Paravertebral Blockade

A Volunteer Study

Daniela Marhofer, Peter Marhofer, Stephan C. Kettner, Edith Fleischmann, Daniela Prayer, Melanie Schernthaner, Edith Lackner, Harald Willschke, Pascal Schwetz, Markus Zeitlinger

Anesthesiology 2013; 118:1106-12, Marhofer et al.

ABSTRACT

Background: This study was designed to examine the spread of local anesthetic (LA) via magnetic resonance imaging after a standardized ultrasound-guided thoracic paravertebral blockade.

Methods: Ten volunteers were enrolled in the study. We performed ultrasound-guided single-shot paravertebral blocks with 20 ml mepivacaine 1% at the thoracic six level at both sides on two consecutive days. After each paravertebral blockade, a magnetic resonance imaging investigation was performed to investigate the three-dimensional spread of the LA. In addition, sensory spread of blockade was evaluated via pinprick testing.

Results: The median (interquartile range) cranial and caudal distribution of the LA relative to the thoracic six puncture level was 1.0 (2.5) and 3.0 (0.75) [=4.0 vertebral levels] for the left and 0.5 (1.0) and 3.0 (0.75) [=3.5 vertebral levels] for the right side. Accordingly, the LA distributed more caudally than cranially. The median (interquartile range) number of sensory dermatomes which were affected by the thoracic paravertebral blockade was 9.8 (6.5) for the left and 10.7 (8.8) for the right side. The sensory distribution of thoracic paravertebral blockade was significantly larger compared with the spread of LA.

Conclusions: Although the spread of LA was reproducible, the anesthetic effect was unpredictable, even with a standardized ultrasound-guided technique in volunteers. While it can be assumed that approximately 4 vertebral levels are covered by 20 ml LA, the somatic distribution of the thoracic paravertebral blockade remains unpredictable. In a significant percentage, the LA distributes into the epidural space, prevertebral, or to the contralateral side.

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2 de maio de 2013

Artigo recomendado: Anesthesia for In Utero Repair of Myelomeningocele

Marla Ferschl, Robert Ball, Hanmin Lee, Mark D. Rollins

Anesthesiology 2013; 118:1211-23, Ferschl et al.


ABSTRACT

Recently published results suggest that prenatal repair of fetal myelomeningocele is a potentially preferable alternative when compared to postnatal repair. In this article, the pathology of myelomeningocele, unique physiologic considerations, perioperative anesthetic management, and ethical considerations of open fetal surgery for prenatal myelomeningocele repair are discussed. Open fetal surgeries have many unique anesthetic issues such as inducing profound uterine relaxation, vigilance for maternal or fetal blood loss, fetal monitoring, and possible fetal resuscitation.

Postoperative management, including the requirement for postoperative tocolysis and maternal analgesia, are also reviewed. The success of intrauterine myelomeningocele repair relies on a well-coordinated multidisciplinary approach. Fetal surgery is an important topic for anesthesiologists to understand, as the number of fetal procedures is likely to increase as new fetal treatment centers are opened across the United States.

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