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Pre-treatment clinical assessment in head and neck cancer: United Kingdom National Multidisciplinary Guidelines
- A Robson, J Sturman, P Williamson, P Conboy, S Penney, H Wood
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- Journal:
- The Journal of Laryngology & Otology / Volume 130 / Issue S2 / May 2016
- Published online by Cambridge University Press:
- 12 May 2016, pp. S13-S22
- Print publication:
- May 2016
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This is the official guideline endorsed by the specialty associations involved in the care of head and neck cancer patients in the UK. This paper provides recommendations on the pre-treatment clinical assessment of patients presenting with head and neck cancer.
Recommendations• Comorbidity data should be collected as it is important in the analysis of survival, quality of life and functional outcomes after treatment as well as for comparing results of different treatment regimens and different centres. (R)
• Patients with hypertension of over 180/110 or associated target organ damage, should have antihypertensive medication started pre-operatively as per British Hypertension Society guidelines. (R)
• Rapidly correcting pre-operative hypertension with beta blockade appears to cause higher mortality due to stroke and hypotension and should not be used. (R)
• Patients with poorly controlled or unstable ischaemic heart disease should be referred for cardiology assessment pre-operatively. (G)
• Patients within one year of drug eluting stents should be discussed with the cardiologist who was responsible for their percutaneous coronary intervention pre-operatively with regard to cessation of antiplatelet medication due to risk of stent thrombosis. (G)
• Patients with multiple recent stents should be managed in a centre with access to interventional cardiology. (G)
• Surgery after myocardial infarction should be delayed if possible to reduce mortality risk. (R)
• Patients with critical aortic stenosis (AS) should be considered for pre-operative intervention. (G)
• Clopidogrel should be discontinued 7 days pre-operatively; warfarin should be discontinued 5 days pre-operatively. (R)
• Patients with thromboembolic disease or artificial heart valves require heparin therapy to bridge peri-operative warfarin cessation, this should start 2 days after last warfarin dose. (R)
• Cardiac drugs other than angotensin-converting enzyme inhibitors and angiotensin II antagonists should be continued including on the day of surgery. (R)
• Angotensin-converting enzyme inhibitors and angiotensin II antagonists should be withheld on the day of surgery unless they are for the treatment of heart failure. (R)
• Post-operative care in a critical care area should be considered for patients with heart failure or significant diastolic dysfunction. (R)
• Patients with respiratory disease should have their peri-operative respiratory failure risk assessed and critical care booked accordingly. (G)
• Patients with severe lung disease should be assessed for right heart disease pre-operatively. (G)
• Patients with pulmonary hypertension and right heart failure will be at extraordinarily high risk and should have the need for surgery re-evaluated. (G)
• Perioperative glucose readings should be kept within 4–12 mmol/l. (R)
• Patients with a high HbA1C facing urgent surgery should have their diabetes management assessed by a diabetes specialist. (G)
• Insulin-dependent diabetic patients must not omit insulin for more than one missed meal and will therefore require an insulin replacement regime. (R)
• Patients taking more than 5 mg of prednisolone daily should have steroid replacement in the peri-operative period. (R)
• Consider proton pump therapy for patients taking steroids in the peri-operative phase if they fit higher risk criteria. (R)
• Surgery within three months of stroke carries high risk of further stroke and should be delayed if possible. (R)
• Patients with rheumatoid arthritis should have flexion/extension views assessed by a senior radiologist pre-operatively. (R)
• Patients at risk of post-operative cognitive dysfunction and delirium should be highlighted at pre-operative assessment. (G)
• Patients with Parkinson's disease (PD) must have enteral access so drugs can be given intra-operatively. Liaison with a specialist in PD is essential. (R)
• Intravenous iron should be considered for anaemia in the urgent head and neck cancer patient. (G)
• Preoperative blood transfusion should be avoided where possible. (R)
• Where pre-operative transfusion is essential it should be completed 24–48 hours pre-operatively. (R)
• An accurate alcohol intake assessment should be completed for all patients. (G)
• Patients considered to have a high level of alcohol dependency should be considered for active in-patient withdrawal at least 48 hours pre-operatively in liaison with relevant specialists. (R)
• Parenteral B vitamins should be given routinely on admission to alcohol-dependent patients. (R)
• Smoking cessation, commenced preferably six weeks before surgery, decreases the incidence of post-operative complications. (R)
• Antibiotics are necessary for clean-contaminated head and neck surgery, but unnecessary for clean surgery. (R)
• Antibiotics should be administered up to 60 minutes before skin incision, as close to the time of incision as possible. (R)
• Antibiotic regimes longer than 24 hours have no additional benefit in clean-contaminated head and neck surgery. (R)
• Repeat intra-operative antibiotic dosing should be considered for longer surgeries or where there is major blood loss. (R)
• Local antibiotic policies should be developed and adhered to due to local resistance patterns. (G)
• Individual assessment for venous thromboembolism (VTE) risk and bleeding risk should occur on admission and be reassessed throughout the patients' stay. (G)
• Mechanical prophylaxis for VTE is recommended for all patients with one or more risk factors for VTE. (R)
• Patients with additional risk factors of VTE and low bleeding risk should have low molecular weight heparin at prophylactic dose or unfractionated heparin if they have severe renal impairment. (R)
Polynomial decay of correlations in linked-twist maps
- J. SPRINGHAM, R. STURMAN
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- Journal:
- Ergodic Theory and Dynamical Systems / Volume 34 / Issue 5 / October 2014
- Published online by Cambridge University Press:
- 04 April 2013, pp. 1724-1746
- Print publication:
- October 2014
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Linked-twist maps are area-preserving, piecewise diffeomorphisms, defined on a subset of the torus. They are non-uniformly hyperbolic generalizations of the well-known Arnold cat map. We show that a class of canonical examples have polynomial decay of correlations for $\alpha $-Hölder observables, of order $1/ n$.
Linked twist map formalism in two and three dimensions applied to mixing in tumbled granular flows
- R. STURMAN, S. W. MEIER, J. M. OTTINO, S. WIGGINS
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- Journal:
- Journal of Fluid Mechanics / Volume 602 / 10 May 2008
- Published online by Cambridge University Press:
- 25 April 2008, pp. 129-174
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We study the mixing properties of two systems: (i) a half-filled quasi-two-dimensional circular drum whose rotation rate is switched between two values and which can be analysed in terms of the existing mathematical formalism of linked twist maps; and (ii) a half-filled three-dimensional spherical tumbler rotated about two orthogonal axes bisecting the equator and with a rotational protocol switching between two rates on each axis, a system which we call a three-dimensional linked twist map, and for which there is no existing mathematical formalism. The mathematics of the three-dimensional case is considerably more involved. Moreover, as opposed to the two-dimensional case where the mathematical foundations are firm, most of the necessary mathematical results for the case of three-dimensional linked twist maps remain to be developed though some analytical results, some expressible as theorems, are possible and are presented in this work. Companion experiments in two-dimensional and three-dimensional systems are presented to demonstrate the validity of the flow used to construct the maps. In the quasi-two-dimensional circular drum, bidisperse (size-varying or density-varying) mixtures segregate to form lobes of small or dense particles that coincide with the locations of islands in computational Poincaré sections generated from the flow model. In the 3d spherical tumbler, patterns formed by tracer particles reveal the dynamics predicted by the flow model.
Convection in a long box driven by heating and cooling on the horizontal boundaries
- J. J. Sturman, G. N. Ivey, J. R. Taylor
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- Journal:
- Journal of Fluid Mechanics / Volume 310 / 10 March 1996
- Published online by Cambridge University Press:
- 26 April 2006, pp. 61-87
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Convection driven by spatially variable heat transfer across the water surface is an important transport mechanism in many geophysical applications. This flow is modelled in a rectangular tank with an aspect ratio, H/L, of 0.1 (where H and L are the tank height and length, respectively). Heat fluxes are applied through horizontal copper plates of length 0.1 L located at the top of one end of the tank and at the bottom of the other end. Experimental flows have been forced with heating at the bottom of the tank and cooling at the top, which gives rise to unstable convection in the end regions. Using water and a glycerol/water mix as the experimental fluids, flow visualization studies and measurements of temperature, velocity and heat flux have been made. Flow visualization studies revealed that complex unsteady turbulent flows occupied the end regions, while cubic velocity profiles characterized the horizontal laminar flow in the interior of the tank. Simple scaling arguments were developed for steady-state velocity and temperature fields, which are in good agreement with the experimental data. In the current experiments the portion of the plates closest to the tank interior (and to the tank endwall in the case of the glycerol/water experiments) were occupied by laminar boundary layers, while the remainder of the plates were occupied by turbulent flow. An effective Rayleigh number Ra* was defined, based upon the portion of the plate occupied by turbulent flow, as was a corresponding modified Nusselt number Nu*. The heat transfer was well predicted by classical Rayleigh-Bénard scaling with the Nusselt number Nu* ∼ Ra*1/3. The range of Ra* was 4.3 × 105 ≤ Ra* ≤ 1.7 × 108. Scaling arguments predicted the triple occupancy of the plates by differing boundary layer regimes within the range of 105 ≤ Ra* ≤ 1014.
Unsteady convective exchange flows in cavities
- J. J. STURMAN, G. N. IVEY
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- Journal:
- Journal of Fluid Mechanics / Volume 368 / 10 August 1998
- Published online by Cambridge University Press:
- 10 August 1998, pp. 127-153
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Horizontal exchange flows driven by spatial variation of buoyancy fluxes through the water surface are found in a variety of geophysical situations. In all examples of such flows the timescale characterizing the variability of the buoyancy fluxes is important and it can vary greatly in magnitude. In this laboratory study we focus on the effects of this unsteadiness of the buoyancy forcing and its influence on the resulting flushing and circulation processes in a cavity. The experiments described all start with destabilizing forcing of the flows, but the buoyancy fluxes are switched to stabilizing forcing at three different times spanning the major timescales characterizing the resulting cavity-scale flows. For destabilizing forcing, these timescales are the flushing time of the region of forcing, and the filling-box timescale, the time for the cavity-scale flow to reach steady state. When the forcing is stabilizing, the major timescale is the time for the fluid in the exchange flow to pass once through the forcing boundary layer. This too is a measure of the time to reach steady state, but it is generally distinct from the filling-box time. When a switch is made from destabilizing to stabilizing buoyancy flux, inertia is important and affects the approach to steady state of the subsequent flow. Velocities of the discharges from the end regions, whether forced in destabilizing or stabilizing ways, scaled as u∼(Bl)1/3 (where B is the forcing buoyancy flux and l is the length of the forcing region) in accordance with Phillips' (1966) results. Discharges with destabilizing and stabilizing forcing were, respectively, Q−∼(Bl)1/3H and Q+∼(Bl)1/3δ (where H is the depth below or above the forcing plate and δ is the boundary layer thickness). Thus Q−/Q+>O(1) provided H>O(δ), as was certainly the case in the experiments reported, demonstrating the overall importance of the flushing processes occurring during periods of cooling or destabilizing forcing.