Category Archives: Publications

Total haemoglobin mass, but not haemoglobin concentration, is associated with preoperative cardiopulmonary exercise testing-derived oxygen-consumption variables.

Otto JM, Plumb JOM, Wakeham D, et al.

Br J Anaesth. 2017;118(5):747-754

Background: Cardiopulmonary exercise testing (CPET) measures peak exertional oxygen consumption ( V O2peak ) and that at the anaerobic threshold ( V O2 at AT, i.e. the point at which anaerobic metabolism contributes substantially to overall metabolism). Lower values are associated with excess postoperative morbidity and mortality. A reduced haemoglobin concentration ([Hb]) results from a reduction in total haemoglobin mass (tHb-mass) or an increase in plasma volume. Thus, tHb-mass might be a more useful measure of oxygen-carrying capacity and might correlate better with CPET-derived fitness measures in preoperative patients than does circulating [Hb]. Methods: Before major elective surgery, CPET was performed, and both tHb-mass (optimized carbon monoxide rebreathing method) and circulating [Hb] were determined. Results: In 42 patients (83% male), [Hb] was unrelated to V O2 at AT and V O2peak ( r =0.02, P =0.89 and r =0.04, P =0.80, respectively) and explained none of the variance in either measure. In contrast, tHb-mass was related to both ( r =0.661, P <0.0001 and r =0.483, P =0.001 for V O2 at AT and V O2peak , respectively). The tHb-mass explained 44% of variance in V O2 at AT ( P <0.0001) and 23% in V O2peak ( P =0.001).
Conclusions: In contrast to [Hb], tHb-mass is an important determinant of physical fitness before major elective surgery. Further studies should determine whether low tHb-mass is predictive of poor outcome and whether targeted increases in tHb-mass might thus improve outcome.

Cardiopulmonary reserve as determined by cardiopulmonary exercise testing correlates with length of stay and predicts complications after radical cystectomy.

Tolchard S, Angell J, Pyke M, et al.

BJU Int. 2015;115(4):554-561

OBJECTIVE: To investigate whether poor preoperative cardiopulmonary reserve and comorbid state dictate high-risk status and can predict complications in patients undergoing radical cystectomy (RC). PATIENTS AND METHODS: In all, 105 consecutive patients with transitional cell carcinoma (TCC; stage T1-T3) undergoing robot-assisted (38 patients) or open (67) RC in a single UK centre underwent preoperative cardiopulmonary exercise testing (CPET). Prospective primary outcome variables were all-cause complications and postoperative length of stay (LOS). Binary logistic regression analysis identified potential predictive factor(s) and the predictive accuracy of CPET for all-cause complications was examined using receiver operator characteristic (ROC) curve analysis. Correlations analysis employed Spearman’s rank correlation and group comparison, the Mann-Whitney U-test and Fisher’s exact test. Any relationships were confirmed using the Mantel-Haenszel common odds ratio estimate, Kaplan-Meier analysis and the chi-squared test.

RESULTS: The anaerobic threshold (AT) was negatively (r = -206, P = 0.035), and the ventilatory equivalent for carbon dioxide (VE/VCO(2)) positively (r = 0.324, P = 0.001) correlated with complications and LOS. Logistic regression analysis identified low AT (<11 mL/kg/min), high VE/VC0(2) (>/=33) and hypertension as significant factors, such that, in their presence patients were 5.55-times more likely to have complications at 90 days postoperatively [P = 0.001, 95% confidence interval (CI) 2.2-13.9]. ROC analysis showed a high significance (area under the curve 0.78, 95% CI 0.69-0.87; P < 0.001). In addition, based on CPET criteria >50% of patients presenting for RC had significant heart failure, whereas preoperatively only very few (2%) had this diagnosis. Analysis using the Mann-Whitney test showed that a VE/VCO(2) >/=33 was the most significant determinant of LOS (P = 0.004). Kaplan-Meier analysis showed that patients in this group had an additional median LOS of 4 days (P = 0.008). Finally, patients with an American Society of Anesthesiologists grade of 3 (ASA 3) and those on long-term beta-blocker therapy were found to be at particular risk of myocardial infarction (MI) and death after RC with odds ratios of 4.0 (95% CI 1.05-15.2; P = 0.042) and 6.3 (95% CI 1.60-24.8; P = 0.008).

CONCLUSION: Patients with poor cardiopulmonary reserve and hypertension are at higher risk of postoperative complications and have increased LOS after RC. Heart failure is known to be a significant determinant of perioperative death and is significantly under diagnosed in this patient group.

Effects of persistent Fontan fenestration patency on cardiopulmonary exercise testing variables.

Heal ME, Jackson LB, Atz AM, Butts RJ

Congenit Heart Dis. 2017 Jun 15. doi: 10.1111/chd.12451. [Epub ahead of print]

Cardiopulmonary exercise testing (CPET) aids in clinical assessment of patients
with Fontan circulation. Effects of persistent fenestration on CPET variables
have not been clearly defined. Associations between fenestration and CPET
variables at anaerobic threshold (AT) and peak exercise were explored in the
Pediatric Heart Network Fontan Cross-Sectional Study cohort. Fenestration patency
was associated with a greater decrease in oxygen saturation from rest to peak
exercise (fenestration -4.9 ± 3.8 v. nonfenestration -3 ± 3.5; P < .001).
Physiological dead space at peak exercise was higher in fenestrated v.
nonfenestrated (25.2 ± 16.1 v. 21.4 ± 15.2; P = .03). There was a weak
association between fenestration patency and maximal work and heart rate.
Fenestration patency was also weakly correlated with oxygen pulse, work and
VE/VCO2 at AT. The effect of persistent fenestration on CPET measurements was
minimal in this study, likely due to the cross-sectional design.

Survival after postoperative morbidity: a longitudinal observational cohort

Moonesinghe SR, Harris S, Mythen MG, et al.

Br J Anaesth. 2014;113(6):977-984

BACKGROUND: Previous studies have suggested that there may be long-term harm associated with postoperative complications. Uncertainty exists however, because of the need for risk adjustment and inconsistent definitions of postoperative morbidity.
METHODS: We did a longitudinal observational cohort study of patients undergoing major surgery. Case-mix adjustment was applied and morbidity was recorded using a validated outcome measure. Cox proportional hazards modelling using time-dependent covariates was used to measure the independent relationship between prolonged postoperative morbidity and longer term survival.
RESULTS: Data were analysed for 1362 patients. The median length of stay was 9 days and the median follow-up time was 6.5 yr. Independent of perioperative risk, postoperative neurological morbidity (prevalence 2.9%) was associated with a relative hazard for long-term mortality of 2.00 [P=0.001; 95% confidence interval (CI) 1.32-3.04]. Prolonged postoperative morbidity (prevalence 15.6%) conferred a relative hazard for death in the first 12 months after surgery of 3.51 (P<0.001; 95% CI 2.28-5.42) and for the next 2 yr of 2.44 (P<0.001; 95% CI 1.62-3.65), returning to baseline thereafter.
CONCLUSIONS: Prolonged morbidity after surgery is associated with a risk of premature death for a longer duration than perhaps is commonly thought; however, this risk falls with time. We suggest that prolonged postoperative morbidity measured in this way may be a valid indicator of the quality of surgical healthcare. Our findings reinforce the importance of research and quality improvement initiatives aimed at reducing the duration and severity of postoperative complications.

The Preoperative Assessment and Optimization of Patients Undergoing Major Urological Surgery

Cui HW, Turney BW, Griffiths J.

Curr Urol Rep. 2017 Jul;18(7):54. doi: 10.1007/s11934-017-0701-z

PURPOSE OF REVIEW: Improving patient outcomes from major urological surgery
requires not only advancement in surgical technique and technology, but also the
practice of patient-centered, multidisciplinary, and integrated medical care of
these patients from the moment of contemplation of surgery until full recovery.
This review examines the evidence for recent developments in preoperative
assessment and optimization that is of relevance to major urological surgery.
RECENT FINDINGS: Current perioperative medicine recommendations aim to improve
the short-term safety and long-term effectiveness of surgical treatments by the
delivery of multidisciplinary integrated medical care. New strategies to deliver
this aim include preoperative risk stratification using a frailty index and
cardiopulmonary exercise testing for patients undergoing intra-abdominal surgery
(including radical cystectomy), preoperative management of iron deficiency and
anemia, and preoperative exercise intervention. Proof of the utility and validity
for improving surgical outcomes through advances in preoperative care is still
evolving. Evidence-based developments in this field are likely to benefit
patients undergoing major urological surgery, but further research targeted at
high-risk patients undergoing specific urological operations is required.

Open label study of ambrisentan in patients with exercise pulmonary hypertension

Segrera SA, Lawler L, Opotowsky AR, Systrom D, Waxman AB.

Pulm Circ. 2017 Apr-Jun;7(2):531-538. doi: 10.1177/2045893217709024. Epub 2017
May 12.

A growing body of evidence suggests that exercise pulmonary hypertension (ePH) is
an early form of pulmonary arterial hypertension (PAH). Identifying the disease
at an early, potentially more responsive phase, and initiating treatment may
improve functional status and prevent progression to severe forms of PAH.
This was a single-center, open-label six-month treatment trial to evaluate the effect
of ambrisentan on pulmonary hemodynamics and exercise capacity in ePH utilizing
invasive cardiopulmonary exercise testing (iCPET). After six months of treatment
with ambrisentan, patients repeated iCPET; exercise capacity, symptoms, and
pulmonary hemodynamics were reassessed. Twenty-two of 30 patients completed the
treatment phase and repeat iCPET. After six months of treatment there was a
significant decline in peak exercise mPAP (-5.2 ± 5.6 mmHg, P = 0.001), TPG
(-7.1 ± 8.0 mmHg, P = 0.001), PVR (-0.9 ± 0.7 Woods units, P = 0.0002), and
Ca-vO2 (-1.8 ± 2.3 mL/dL, P = 0.0002), with significant increases in peak PCWP
(+2.9 ± 5.6 mmHg, P = 0.02), PVC (+0.8 ± 1.4 mL/mmHg, P = 0.03), and CO
(+2.3 ± 1.4 L/min, P = 0.0001). A trend toward increased VO2max (+4.4 ± 2.6%
predicted, P = 0.07) was observed. In addition, there were improvements in 6MWD
and WHO FC after 24 weeks.
Our findings suggest that treatment of ePH with
ambrisentan results in improved pulmonary hemodynamics and functional status over
a six-month period. Treatment of ePH may prevent the progression of vascular
remodeling and development of established PAH.

Exercise Testing, Supplemental Oxygen and Hypoxia.

Ward SA; Human Bio-Energetics Research Centre, Crickhowell, United Kingdom of Great Britain and Northern Ireland ; saward@dsl.pipex.com.
Grocott MP; University of Southampton, 7423, Anaesthesia and Critical Care Research Unit, Faculty of Medicine, Southampton, Hampshire, United Kingdom of Great Britain and Northern Ireland ; m.grocott@soton.ac.uk.
Levett DZ; University of Southampton, Anaesthesia and Critical Care Research Unit, Faculty of Medicine, Southampton, Hampshire, United Kingdom of Great Britain and Northern Ireland ; d.levett@soton.ac.uk.

Annals Of The American Thoracic Society [Ann Am Thorac Soc] 2017 Jun 07. Date of Electronic Publication: 2017 Jun 07.

Cardiopulmonary exercise testing (CPET) in hyperoxia and hypoxia has several applications, stemming from characterization of abnormal physiological response profiles associated with exercise intolerance. As altered oxygenation can impact on the performance of gas-concentration and flow sensors and pulmonary gas exchange algorithms, integrated CPET system function requires validation under these conditions. Also, as oxygenation status can influence peak O2 uptake, care should be taken in the selection of work-rate incrementation rates when CPET performance is to be compared with sea-level. CPET has been used to evaluate the effects of supplemental O2 on exercise intolerance in chronic obstructive pulmonary disease, interstitial pulmonary fibrosis and cystic fibrosis at sea-level. However, identification of those CPET indices likely to be predictive of supplemental O2 outcomes for exercise tolerance at altitude in such patients is lacking. CPET performance with supplemental O2 in respiratory patients residing at high altitudes is poorly studied. Finally, CPET has the potential to give physiological and clinical information about acute and chronic mountain sickness, high-altitude pulmonary edema, and high-altitude cerebral edema. It can translate high-altitude acclimatization and adaptive processes in healthy individuals into intensive care medical practice.

Cardiopulmonary Exercise Testing and Metabolic Myopathies.

Riley MS; Belfast City Hospital, Regional Respiratory Centre, Belfast, United Kingdom of Great Britain and Northern Ireland ; marshall.riley@belfasttrust.hscni.net.
Nicholls DP; Royal Victoria Hospital, Department of Medicine, Belfast, United Kingdom of Great Britain and Northern Ireland ; paul.nicholls@belfasttrust.hscni.net.
Cooper CB; Harbor-UCLA Medical Center , Div of Respiratory/Physiology & Medicine , 1000 W Carson Street , Torrance, California, United States , 90509 ; ccooper@mednet.ucla.edu.

Annals Of The American Thoracic Society [Ann Am Thorac Soc] 2017 Jun 07. Date of Electronic Publication: 2017 Jun 07.

Skeletal muscle requires a large increase in its adenosine triphosphate production to meet the energy needs of exercise. Normally, most of this increase in energy is supplied by the aerobic process of oxidative phosphorylation. The main defects in muscle metabolism that interfere with production of adenosine triphosphate are a) disorders of glycogenolysis and glycolysis, which prevent both carbohydrate entering the tricarboxylic acid cycle and the production of lactic acid, b) mitochondrial myopathies where the defect is usually within the electron transport chain, reducing the rate of oxidative phosphorylation and c) disorders of lipid metabolism. Gas exchange measurements derived from exhaled gas analysis during cardiopulmonary exercise testing can identify defects in muscle metabolism because oxygen consumption and carbon dioxide production are abnormal at the level of the muscle. Cardiopulmonary exercise testing may thus suggest a likely diagnosis and guide additional investigation. Defects in glycogenolysis and glycolysis are identified by a low peak oxygen uptake and absence of excess carbon dioxide production from buffering of lactic acid by bicarbonate. Defects in the electron transport chain also result in low peak oxygen uptake, but because there is an over-reliance on anaerobic processes, lactic acid accumulation and excess carbon dioxide from buffering occur early during exercise. Defects in lipid metabolism result in only minor abnormalities during cardiopulmonary exercise testing. In defects of glycogenolysis and glycolysis and in mitochondrial myopathies other features may include an exaggerated cardiovascular response to exercise, a low oxygen-pulse and excessive ammonia release.

Perioperative fluid therapy: a statement from the international Fluid Optimization Group

 

  • Lais Helena Camacho NavarroEmail author,
  • Joshua A Bloomstone,
  • Jose Otavio Costa AulerJr,
  • Maxime Cannesson,
  • Giorgio Della Rocca,
  • Tong J Gan,
  • Michael Kinsky,
  • Sheldon Magder,
  • Timothy E Miller,
  • Monty Mythen,
  • Azriel Perel,
  • Daniel A Reuter,
  • Michael R Pinsky and
  • George C Kramer
Perioperative Medicine2015 4:3

Background

Perioperative fluid therapy remains a highly debated topic. Its purpose is to maintain or restore effective circulating blood volume during the immediate perioperative period. Maintaining effective circulating blood volume and pressure are key components of assuring adequate organ perfusion while avoiding the risks associated with either organ hypo- or hyperperfusion. Relative to perioperative fluid therapy, three inescapable conclusions exist: overhydration is bad, underhydration is bad, and what we assume about the fluid status of our patients may be incorrect. There is wide variability of practice, both between individuals and institutions. The aims of this paper are to clearly define the risks and benefits of fluid choices within the perioperative space, to describe current evidence-based methodologies for their administration, and ultimately to reduce the variability with which perioperative fluids are administered.

Methods

Based on the abovementioned acknowledgements, a group of 72 researchers, well known within the field of fluid resuscitation, were invited, via email, to attend a meeting that was held in Chicago in 2011 to discuss perioperative fluid therapy. From the 72 invitees, 14 researchers representing 7 countries attended, and thus, the international Fluid Optimization Group (FOG) came into existence. These researches, working collaboratively, have reviewed the data from 162 different fluid resuscitation papers including both operative and intensive care unit populations. This manuscript is the result of 3 years of evidence-based, discussions, analysis, and synthesis of the currently known risks and benefits of individual fluids and the best methods for administering them.

Results

The results of this review paper provide an overview of the components of an effective perioperative fluid administration plan and address both the physiologic principles and outcomes of fluid administration.

Conclusions

We recommend that both perioperative fluid choice and therapy be individualized. Patients should receive fluid therapy guided by predefined physiologic targets. Specifically, fluids should be administered when patients require augmentation of their perfusion and are also volume responsive. This paper provides a general approach to fluid therapy and practical recommendations.

 

High-intensity interval training (HIT) for effective and time-efficient pre-surgical exercise interventions

 

  • Matthew Weston
  • Kathryn L Weston,
  • James M. Prentis and
  • Chris P Snowden
Perioperative Medicine20165:2

DOI: 10.1186/s13741-015-0026-8

The advancement of perioperative medicine is leading to greater diversity in development of pre-surgical interventions, implemented to reduce patient surgical risk and enhance post-surgical recovery. Of these interventions, the prescription of pre-operative exercise training is gathering momentum as a realistic means for enhancing patient surgical outcome. Indeed, the general benefits of exercise training have the potential to pre-operatively optimise several pre-surgical risks factors, including cardiorespiratory function, frailty and cognitive function.

Any exercise programme incorporated into the pre-operative pathway of care needs to be effective and time efficient in that any fitness gains are achievable in the limited period between the decision for surgery and operation (e.g. 4 weeks). Fortunately, there is a large volume of research describing effective and time-efficient exercise training programmes within the discipline of sports science. Accordingly, the objective of our commentary is to synthesise contemporary exercise training research, both from non-clinical and clinical populations, with the overarching aim of informing the development of effective and time-efficient pre-surgical exercise training programmes.

The development of such exercise training programmes requires the careful consideration of several key principles, namely frequency, intensity, time, type and progression of exercise. Therefore, in light of more recent evidence demonstrating the effectiveness and time efficiency of high-intensity interval training—which involves brief bouts of intense exercise interspersed with longer recovery periods—the principles of exercise training programme design will be discussed mainly in the context of such high-intensity interval training programmes. Other issues pertinent to the development, implementation and evaluation of pre-operative exercise training programmes, such as individual exercise prescription, training session monitoring and potential barriers and risks to high-intensity exercise are also discussed. The evidence presented suggests that individually prescribed and supervised high-intensity interval training programmes, encompassing a variety of exercise modes represent an effective and safe means of exercise therapy prior to surgery.