BACKGROUND:Type A aortic dissection repair is one of the most common emergency cardiac surgical procedures undertaken in the UK and has a high mortality. Early diagnosis and prompt surgery by an expert cardiac surgical team is crucial. Little is known about the patient's journey from first symptoms until surgery. METHODS:The Association for Cardiothoracic Anaesthesia and Critical Care undertook a prospective national audit of the management of type A aortic dissection in the UK. RESULTS:The details of 334 patients with type A aortic dissection were reported by 28 UK cardiac centres over 12 months. Median (IQR [range]) time from onset of symptoms until arrival in an emergency department was 2.3 (1.4-4.7 [0.1-491.6]) h. Median (IQR [range]) time between arrival in the emergency department and the start of surgery was 9.5 (6.1-18.2 [0.8-363.5]) h. Delays in diagnosis and transfers were reported in 158 (47.3%) patients. Fifty-two patients (15.6%) had an initial misdiagnosis. The condition of 56 patients (16.8%) deteriorated clinically before arrival in the operating theatre. A medical doctor accompanied 50 patients (15.0%) during transfer. Sixty-four patients (19.2%) died in hospital with 41 (12.3%) dying within the first 5 days after surgery. CONCLUSIONS:This audit provides a snapshot of current practice for patients with type A aortic dissection in the UK. Our findings show the acuity, clinical severity and vulnerability of patients with type A aortic dissection, and the deficits in the process of diagnosis and the quality of transfer. This audit demonstrates the need for the implementation of comprehensive, regionally governed, interdisciplinary medical management for every patient with type A aortic dissection.

It has been suggested that a larger heparin dose during cardiopulmonary bypass (CPB) is associated with reduced perioperative coagulopathy and thromboembolic complications. We investigated the effect of different heparin doses during routine elective cardiac surgery. Our primary outcomes include blood loss and transfusion and secondary outcomes investigate the effects on coagulation biomarkers. In this prospective pilot trial, we allocated 60 patients undergoing cardiac surgery on CPB in a single tertiary cardiac centre into three groups to receive an initial dose of 300, 400, or 500 units (U) per kilogram of intravenous heparin prior to the commencement of CPB. Blood was sampled after induction of anesthesia, at 30 and 60 min of CPB, and three minutes after heparin reversal with protamine. Samples were analyzed for fibrinopeptide A (FPA), fibrinopeptide B (FPB), D-dimer, and thrombin-antithrombin (TAT) complexes. Postoperative blood loss and transfusion was measured for the first 24-hr period after surgery. The total mean (95

Aortic dissections are associated with significant mortality and morbidity, with rapid treatment paramount. They are caused by a tear in the intimal lining of the aorta that extends into the media of the wall. Blood flow through this tear leads to the formation of a false passage bordered by the inner and outer layers of the media. Their diagnosis is challenging, with most deaths caused by aortic dissection diagnosed at post-mortem. Aortic dissections are classified by location and chronicity, with management strategies depending on the nature of the dissection. The Stanford method splits aortic dissections into type A and B, with type A dissections involving the ascending aorta. De Bakey classifies dissections into I, II or III depending on their origin and involvement and degree of extension. The key to diagnosis is early suspicion, appropriate imaging and rapid initiation of treatment. Treatment focuses on initial resuscitation, transfer (if possible and required) to a suitable specialist centre, strict blood pressure and heart rate control and potentially surgical intervention depending on the type and complexity of the dissection. Effective post-operative care is extremely important, with awareness of potential post-operative complications and a multi-disciplinary rehabilitation approach required. In this review article we will discuss the aetiology and classifications of aortic dissection, their diagnosis and treatment principles relevant to critical care. Critical care clinicians play a key part in all these steps, from diagnosis through to post-operative care, and thus a thorough understanding is vital.

Knowledge and application of respiratory pharmacology is essential for both anaesthetists and intensive care physicians. Patients often present with co-existing respiratory disease for which they may be taking prescription medications. Respiratory function is often altered by anaesthetic drugs and interventions, therefore an in-depth understanding of respiratory pathophysiology and pharmacology is required in order to safely treat these patients. This article describes the basics of the bronchial tone, the ability of the lung to handle and metabolize drugs in addition to discussion of the drugs that can be used to alter bronchial tone and pulmonary vascular resistance.

BackgroundThe dose of protamine required following cardiopulmonary bypass (CPB) is often determined by the dose of heparin required pre-CPB, expressed as a fixed ratio. Dosing based on mathematical models of heparin clearance is postulated to improve protamine dosing precision and coagulation. We hypothesised that protamine dosing based on a 2-compartment model would improve thromboelastography (TEG) parameters and reduce the dose of protamine administered, relative to a fixed ratio.Methods and findingsWe undertook a 2-stage, adaptive randomised controlled trial, allocating 228 participants to receive protamine dosed according to a mathematical model of heparin clearance or a fixed ratio of 1 mg of protamine for every 100 IU of heparin required to establish anticoagulation pre-CPB. A planned, blinded interim analysis was undertaken after the recruitment of 50% of the study cohort. Following this, the randomisation ratio was adapted from 1:1 to 1:1.33 to increase recruitment to the superior arm while maintaining study power. At the conclusion of trial recruitment, we had randomised 121 patients to the intervention arm and 107 patients to the control arm. The primary endpoint was kaolin TEG r-time measured 3 minutes after protamine administration at the end of CPB. Secondary endpoints included ratio of kaolin TEG r-time pre-CPB to the same metric following protamine administration, requirement for allogeneic red cell transfusion, intercostal catheter drainage at 4 hours postoperatively, and the requirement for reoperation due to bleeding. The trial was listed on a clinical trial registry (ClinicalTrials.govIdentifier: NCT03532594).Participants were recruited between April 2018 and August 2019. Those in the intervention/model group had a shorter mean kaolin r-time (6.58 [SD 2.50] vs. 8.08 [SD 3.98] minutes;p= 0.0016) post-CPB. The post-protamine thromboelastogram of the model group was closer to pre-CPB parameters (median pre-CPB to post-protamine kaolin r-time ratio 0.96 [IQR 0.78–1.14] vs. 0.75 [IQR 0.57–0.99];p< 0.001). We found no evidence of a difference in median mediastinal/pleural drainage at 4 hours postoperatively (140 [IQR 75–245] vs. 135 [IQR 94–222] mL;p= 0.85) or requirement (as a binary outcome) for packed red blood cell transfusion at 24 hours postoperatively (19 [15.8%] vs. 14 [13.1%]p= 0.69). Those in the model group had a lower median protamine dose (180 [IQR 160–210] vs. 280 [IQR 250–300] mg;p< 0.001).Important limitations of this study include an unblinded design and lack of generalisability to certain populations deliberately excluded from the study (specifically children, patients with a total body weight >120 kg, and patients requiring therapeutic hypothermia to <28°C).ConclusionsUsing a mathematical model to guide protamine dosing in patients following CPB improved TEG r-time and reduced the dose administered relative to a fixed ratio. No differences were detected in postoperative mediastinal/pleural drainage or red blood cell transfusion requirement in our cohort of low-risk patients.Trial registrationClinicalTrials.gov Unique identifierNCT03532594.

In animals that maintain body temperature within a tight range (homeotherms), thermoregulation represents the balance between heat production (thermogenesis) and heat loss. Thermogenesis occurs as a result of metabolic activity, particularly in skeletal muscle, the kidneys, the brain, the liver and (in infants) adipose tissue. Body heat is lost by conduction, convection, radiation and evaporation (Table 24.1). Cold-induced hypothalamic stimulation activates autonomic, extra-pyramidal, endocrine and behavioural mechanisms to maintain the core temperature.

A comprehensive review of the complications of cardiac surgery would fill an entire volume. This chapter covers the more common and life-threatening complications. The reader is directed to the publications list under further reading.

Since its introduction into clinical practice in the early 1950s, the indications for CPB have broadened, from operations on or within the heart, to include non-cardiac thoracic, abdominal and neurological procedures. The indications for CPB for non-cardiac surgery are shown in Box 28.1.

Introduction Type A aortic dissections are a surgical emergency, with roughly 2500 cases per year in England (1). About 20% of patients die before reaching a hospital and about 50% die before reaching a specialist centre, with reported delays in diagnoses in around 16 – 40% of cases (1). There is little knowledge about current logistics and practise by cardiac anaesthetic centres in the UK. We therefore conducted a survey, supported by the Association for Cardiothoracic Anaesthesia and Critical Care (ACTACC) network. Methods We sent a 17-question survey to 28 ACTACC link-persons in UK cardiac centres in February 2020. Data was collected and collated using the web-based survey platform “Survey Monkey” (Palo Alto, CA). Results The response rate was 68% (n=18). The majority of centres (73%, n=13) shared aortic dissection services with 1-3 other cardiac centres in their region. A majority of centres (n=13, 72%) reported that the maximum duration of ambulance transfer within their region was 90 minutes or less. In the remaining centres travel times were between 2-6 hours. A small majority of the respondents felt that there was often or always a delay in diagnoses and transfer of Type A aortic dissection patients to cardiothoracic centres (n=11, 61% and n=10, 56% respectively). Monitoring and blood pressure treatment of patients with acute Type A aortic dissections were only sometimes or rarely appropriate, as indicated by the majority of respondents with n=12 (67%) and n=15 (83%), respectively. The majority reported that escorting personnel was only sometimes or rarely experienced or trained (n=13, 72%). Half of the respondents assessed handover as often or always appropriate (n=9, 50%). The ideal destination at arrival for patients with acute Type A aortic dissections was the critical care unit in the majority (n=12, 67%) of centres, with 5 centres preferring theatre (28%). There was agreement from respondents that guidelines regarding the transfer of acute Type A aortic dissection patients would be beneficial. Discussion This survey of UK cardiac centres shows that the majority of centres already centralise treatment of Type A aortic dissection patients by sharing responsibilities. Furthermore, it reflects the observation by the majority of ACTACC link persons that there may be room for improvement of a timely diagnosis, transfer times, monitoring, and training and experience of escorting personnel. In the future a national prospective audit of acute Type A dissection cases in the UK will be necessary to further assess timely diagnoses and quality of transfer-related variables in individual patients with the view of elucidating how to potentially reduce the high incidence of pre-hospital deaths of patients with acute Type A aortic dissection. This survey was conducted before the COVID-19 pandemic. A future audit would help to assess NHS treatment of acute Type A aortic dissections after the pandemic peak.

Possession of the diploma of Fellow of the Royal College of Anaesthetists (FRCA) is an essential requirement for trainees in anesthesia in the United Kingdom. The final FRCA examination is typically attempted midway through the current 5-yr United Kingdom training program (postgraduate year 7), and it represents the gateway to higher specialist training in anesthesia.The written component of the final FRCA examination comprises two papers: a short answer question paper and a multiple choice paper consisting of 60 true–false multiple choice questions (MCQs) and 30 single best answer (SBA) questions. SBAs have been included in both primary and final FRCA examinations since 2010–2011. SBAs are considered to be much better at testing reasoning and clinical judgment than traditional MCQs. Although a good number of books providing examples of MCQs are available, there are still relatively few anesthetic texts that specifically cover SBAs. Get through Final FRCA Single Best Answers seeks to address this deficiency and, perhaps somewhat reassuringly, all of the authors possess the FRCA diploma!The book provides five separate practice papers, each with 30 SBAs followed by the answers and a detailed discussion of the plausible options. From an examiner’s perspective, SBA questions should adhere to certain “house rules”: a clinically relevant, unambiguous, and comprehensive question stem no more than three sentences in length, followed by five homogeneous plausible answers of similar length, forming a grammatically consistent and logically consistent continuum, arranged in alphabetical order. One of the five answers is considered “best,” and it should be possible to read and answer each SBA in less than 1 min without reference to the five listed options. Writing good SBAs is difficult, time-consuming and best done by examiners (or authors) working in small groups.Get through Final FRCA Single Best Answers covers a wide range of relevant subjects in clinical anesthesia, intensive care medicine, and pain management. Although the SBA options are not listed in alphabetic order, the authors have successfully avoided the common SBA writing pitfalls—spelling and grammatical errors, element repetition, and use of extremes such as “never,” “only,” and “always”—that inadvertently cue a reader to the correct answer. The answers and discussion sections provide a clear and logical question-by-question explanation of why the correct answer is the best answer. Each question discussion has at least one reference to a relevant peer-reviewed publication or practice guideline. Although it is intended that each practice examination paper be tackled under examination conditions in a 30-min block of time, the extensive index allows the more impatient reader to target specific areas for revision.From a candidate’s perspective, the book is reasonably priced and pocket-sized, making it ideal for both strategic and “on-the-go” studying. It is well laid out, and the answers are comprehensive and form a good learning tool. This sheds some light on the best technique for correctly answering SBAs, an art in itself and best learned through practice. The most useful aspect of the book is that the questions are up to date, and the authors cite recent published recommendations and clinical guidelines. The level of difficulty of the questions is perhaps a little greater than SBAs appearing in current final FRCA examinations, but nevertheless it is a very useful asset for revision and is highly recommended.

The cardiopulmonary bypass (CPB) circuit must be primed with a fluid solution. The volume of prime required is either based on a standard empirically derived volume greater than a minimum safe priming volume, or may be guided by the patient's weight or body surface area. The initial hematocrit (HCT) achieved after initiation of CPB is determined by the volume of the prime in relation to the patient's pre-CPB HCT. There are many different recipes for priming solutions using crystalloid, colloid or blood as primary constituents. Blood was used to prime the CPB circuit in an attempt to preserve a high hematocrit; early in the evolution of CPB this was thought to be an important determinant for successful outcome. The idea of using oxygen-carrying solutions as blood substitutes may be an attractive means of maintaining oxygen delivery. They would address the expense, limited supply and disease transmission associated with blood transfusion.

Despite the widespread availability of investigational tests and imaging techniques for the diagnosis and management of cardiac disease, eliciting a comprehensive history and performing a systematic physical examination remain essential clinical skills.