Andrew Ferguson

Gram-positive toxic shock syndromes

Toxic shock syndrome (TSS) is an acute, multi-system, toxin-mediated illness, often resulting in multi-organ failure. It represents the most fulminant expression of a spectrum of diseases caused by toxin-producing strains of Staphylococcus aureus and Streptococcus pyogenes (group A streptococcus). The importance of Gram-positive organisms as pathogens is increasing, and TSS is likely to be underdiagnosed in patients with staphylococcal or group A streptococcal infection who present with shock. TSS results from the ability of bacterial toxins to act as superantigens, stimulating immune-cell expansion and rampant cytokine expression in a manner that bypasses normal MHC-restricted antigen processing. A repetitive cycle of cell stimulation and cytokine release results in a cytokine avalanche that causes tissue damage, disseminated intravascular coagulation, and organ dysfunction. Specific therapy focuses on early identification of the illness, source control, and administration on antimicrobial agents including drugs capable of suppressing toxin production (eg, clindamycin, linezolid). Intravenous immunoglobulin has the potential to neutralise superantigen and to mitigate subsequent tissue damage.

Perioperative acute kidney injury: risk factors, recognition, management, and outcomes

#### Summary points Perioperative acute kidney injury (AKI) is common but poorly recognised and managed Perioperative AKI increases surgical mortality and morbidity and increases cost An apparently successful surgical outcome may not mean a successful renal outcome Careful and thoughtful preoperative assessment, including identifying patients with existing chronic kidney disease and stopping and avoiding nephrotoxic drugs, will reduce the incidence of perioperative AKI. Management of AKI centres on optimising fluid status and blood pressure, treating sepsis, and removing nephrotoxic agents where possible Patients with AKI are often complex to treat, and senior help should be sought at an early stage Acute kidney injury (AKI), formerly known as “acute renal failure,” is associated with increased morbidity, mortality, duration of hospital stay, and healthcare cost.w1 Despite this, published data on perioperative acute kidney injury, occurring between the time of admission for surgery and the time of discharge, are scarce outside the cardiovascular surgery setting. Regardless of the clinical setting, the diagnosis of AKI is often delayed, and treatment is suboptimal in a large proportion of cases.1 To improve diagnosis and treatment, clinicians need to understand the risks and triggers for perioperative AKI, the association of even small transient rises in creatinine concentration with risk of death,2 and what actions they need to take promptly on diagnosis. The term acute kidney injury reflects the importance of thinking of the condition as a spectrum or continuum of disease that may be recognised at an early stage, rather than as an “all or nothing” phenomenon as implied by the term acute renal failure. Recognising earlier stages of renal impairment allows for early appropriate action that may interrupt a process of functional decline. In this article we recommend the introduction of systems to ensure that changes in creatinine concentration from baseline are urgently highlighted to the …

Perioperative management of the hemodialysis patient.

Dialysis‐dependent chronic kidney disease (CKD) is an expanding problem for healthcare systems worldwide. The prevalence of end‐stage renal disease (ESRD) has increased by 20% since 2000 and stands at 1699 per million people in the USA. ESRD is associated with an increased risk of cardiovascular comorbidity, increased severity of cardiovascular disease, and an adjusted all‐cause mortality rate that is 6.4–7.8‐fold higher than the general population. These patients may present electively or emergently for surgery related to, or remote from, the CKD. In any perioperative setting, the patient with hemodialysis‐dependent CKD represents a significant clinical challenge, and successful management of these patients requires effective cooperation and communication between nephrology, anesthesia, and surgical staff. The ESRD patient’s nephrologist will have the best knowledge of their medical history, comorbidities, and future management goals and may have been the clinician who instigated the referral for the surgery, e.g., for parathyroidectomy, vascular access surgery, nephrectomy or renal transplantation. As such, they are in an ideal position to contribute to, or coordinate, early preoperative medical optimization of the patient and also to provide advice during postoperative recovery and rehabilitation. In this article, we provide an overview of some of the key aspects of managing these patients successfully during the perioperative period. We propose the integration of cardiopulmonary exercise testing and cardiovascular optimization into the care of these high‐risk patients and provide an overview of the importance of maintaining microvascular perfusion and the role of viscosity in preserving the capillary perfusion network.

Staphylococcal Toxic Shock Syndrome: Mechanisms and Management

Staphylococcal toxic shock syndrome is a rare complication of Staphylococcus aureus infection in which bacterial toxins act as superantigens, activating very large numbers of T cells and generating an overwhelming immune-mediated cytokine avalanche that manifests clinically as fever, rash, shock, and rapidly progressive multiple organ failure, often in young, previously healthy patients. The syndrome can occur with any site of S. aureus infection, and so clinicians of all medical specialties should have a firm grasp of the presentation and management. In this article, we review the literature on the pathophysiology, clinical features, and treatment of this serious condition with emphasis on recent insights into pathophysiology and on information of relevance to the practicing clinician.

Bishop Harman Test for Night Vision

usually possess suitable equipment for calibrating such instruments. Yet it appears that such bulbs, with a good voltmeter or ammeter, provide the best light source. I have measured the candle-power of two of the standard candles provided for the Bishop Harman test in their draughtproof lamphouse, and found that during the first 40 minutes of burning there was a gradual increase from 0.75 to 2.0 c.p., and after that a decline to 0.6 c.p. without there being evidence of anything wrong with the candle. After this the candle failed in each case to move up in its spring socket, though there was about l in. unburnt; if this escaped notice the light dropped further to 0.2 c.p. Thus the light varies over a threefold range when the instrument appears to be functioning properly, ancd if one does not watch the behaviour of the candle carefully a tenfold change can occur. The literature indicates twofold or threefold threshold changes as significant in vitamin A deficiency, and suggests that the individual variation in thresholds among a large population, excluding cases of retinitis pigmentosa and other pathological conditions, is about sixteenfold. Thus a twofold or threefold variation in light can be very serious for clinical purposes, and a variation as great as tenfold would invalidate the test even for rough personnel-selection purposes. An endeavour should be made to achieve about ± 15% in the accuracy of night-vision tests for such work.

Redesign of the System for Evaluation of Teaching Qualities in Anesthesiology Residency Training (setq Smart)

Background:Given the increasing international recognition of clinical teaching as a competency and regulation of residency training, evaluation of anesthesiology faculty teaching is needed. The System for Evaluating Teaching Qualities (SETQ) Smart questionnaires were developed for assessing teaching performance of faculty in residency training programs in different countries. This study investigated (1) the structure, (2) the psychometric qualities of the new tools, and (3) the number of residents’ evaluations needed per anesthesiology faculty to use the instruments reliably. Methods:Two SETQ Smart questionnaires—for faculty self-evaluation and for resident evaluation of faculty—were developed. A multicenter survey was conducted among 399 anesthesiology faculty and 430 residents in six countries. Statistical analyses included exploratory factor analysis, reliability analysis using Cronbach &agr;, item-total scale correlations, interscale correlations, comparison of composite scales to global ratings, and generalizability analysis to assess residents’ evaluations needed per faculty. Results:In total, 240 residents completed 1,622 evaluations of 247 faculty. The SETQ Smart questionnaires revealed six teaching qualities consisting of 25 items. Cronbach &agr;’s were very high (greater than 0.95) for the overall SETQ Smart questionnaires and high (greater than 0.80) for the separate teaching qualities. Interscale correlations were all within the acceptable range of moderate correlation. Overall, questionnaire and scale scores correlated moderately to highly with the global ratings. For reliable feedback to individual faculty, three to five resident evaluations are needed. Conclusions:The first internationally piloted questionnaires for evaluating individual anesthesiology faculty teaching performance can be reliably, validly, and feasibly used for formative purposes in residency training.

Weaning patients off invasive ventilation

Non-invasive ventilation may improve outcomes in selected patients, but the evidence is weak

Perioperative care of patients undergoing non-elective laparatomy in a district general hospital

Results Data were collected for 43 patients (24 female), 65.1% were aged 60-79 years and 62.3% were ASA 3. Preoperatively 16.3% received level 2 or 3 care. Prior to non-elective laparotomy 23.3% of patients had previous abdominal surgery within the preceding 11 days. Seventy-three percent of surgeries were conducted from 08:00 to 17:59 (5% from 00:00 to 07:59). Consultant surgeon and consultant anaesthetist were present intraoperatively in 80% and 72.5% of cases respectively and in 55% of cases were present together. Immediate post-operative care was as follows: 46.5% post anaesthetic care unit (PACU), 11.6% level 2 (non-PACU) and 41.9% level 3 care. From PACU, a further 15% were transferred to higher level care at 6 hours. Mean length of stay in critical care 3.36 days (range 0.5 15.5 days) and in hospital 24 days (range 3 65 days). The overall incidence of perioperative AKI between day 4 preoperatively and day 7 postoperatively according to AKIN classification and/or serum NGAL was 67.4%. AKIN 3 was reached in 11.6% of patients and 7.0% received haemodiafiltration. AKI was unresolved at day 7 in 11.6%. Post-operative proforma were completed daily for ≥4 days in 37 patients. Within the first 4-7 post-operative days, 14 patients required TPN, 4 patients had an episode of atrial fibrillation, 3 developed pneumonia, 3 congestive cardiac failure and 3 required a further laparotomy. Three patients were dead at 30 days.

Surgery and Chronic Kidney Disease

The number of patients with CKD presenting for major noncardiac or cardiac surgery is increasing as CKD prevalence continues to rise. All CKD patients being referred for surgery should be carefully evaluated through history, physical examination, and investigations to determine the status of their kidney disease and the nature and extent of comorbidities and complications. Echocardiography will assist in anesthesia planning by identifying higher-risk features such as severe hypertrophy, systolic or diastolic impairment, pulmonary hypertension, and aortic sclerosis. The success of surgery in the CKD patient depends to a significant extent on preoperative preparation which centers around optimizing the comorbid diseases and making a clear determination on perioperative risk. Patients with CKD are at higher risk of AKI in the perioperative period, and careful attention is required to minimize tissue trauma, manage medications appropriately, optimize fluid balance, maintain perfusion pressure and cardiac output, and aggressively treat complications throughout the perioperative period. There are no “magic bullets” for renal protection, perhaps with the exception of using off-pump CABG techniques where suitable. CKD patients with significant comorbidity will require more invasive monitoring for surgery. Suitable anesthesia techniques include general anesthesia using intravenous or volatile agents, regional anesthesia (nerve block techniques) for peripheral surgery, or neuraxial anesthesia (spinal or epidural). Postoperatively, drugs such as opioids require careful dosing. Usual medications should be restarted when the patient is sufficiently stable.

Staphylococcal infections: beyond "conventional" sepsis.

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