Category Archives: Publications

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.

 

Aerobic or Resistance Exercise, or Both, in Dieting Obese Older Adults

Villareal DT, Aguirre L, Gurney AB, et al.

N Engl J Med. 2017;376(20):1943-1955

BACKGROUND: Obesity causes frailty in older adults; however, weight loss might accelerate age-related loss of muscle and bone mass and resultant sarcopenia and osteopenia.
METHODS: In this clinical trial involving 160 obese older adults, we evaluated the effectiveness of several exercise modes in reversing frailty and preventing reduction in muscle and bone mass induced by weight loss. Participants were randomly assigned to a weight-management program plus one of three exercise programs – aerobic training, resistance training, or combined aerobic and resistance training – or to a control group (no weight-management or exercise program). The primary outcome was the change in Physical Performance Test score from baseline to 6 months (scores range from 0 to 36 points; higher scores indicate better performance). Secondary outcomes included changes in other frailty measures, body composition, bone mineral density, and physical functions.
RESULTS: A total of 141 participants completed the study. The Physical Performance Test score increased more in the combination group than in the aerobic and resistance groups (27.9 to 33.4 points [21% increase] vs. 29.3 to 33.2 points [14% increase] and 28.8 to 32.7 points [14% increase], respectively; P=0.01 and P=0.02 after Bonferroni correction); the scores increased more in all exercise groups than in the control group (P<0.001 for between-group comparisons). Peak oxygen consumption (milliliters per kilogram of body weight per minute) increased more in the combination and aerobic groups (17.2 to 20.3 [17% increase] and 17.6 to 20.9 [18% increase], respectively) than in the resistance group (17.0 to 18.3 [8% increase]) (P<0.001 for both comparisons). Strength increased more in the combination and resistance groups (272 to 320 kg [18% increase] and 288 to 337 kg [19% increase], respectively) than in the aerobic group (265 to 270 kg [4% increase]) (P<0.001 for both comparisons). Body weight decreased by 9% in all exercise groups but did not change significantly in the control group. Lean mass decreased less in the combination and resistance groups than in the aerobic group (56.5 to 54.8 kg [3% decrease] and 58.1 to 57.1 kg [2% decrease], respectively, vs. 55.0 to 52.3 kg [5% decrease]), as did bone mineral density at the total hip (grams per square centimeter; 1.010 to 0.996 [1% decrease] and 1.047 to 1.041 [0.5% decrease], respectively, vs. 1.018 to 0.991 [3% decrease]) (P<0.05 for all comparisons). Exercise-related adverse events included musculoskeletal injuries.
CONCLUSIONS: Of the methods tested, weight loss plus combined aerobic and resistance exercise was the most effective in improving functional status of obese older adults. (Funded by the National Institutes of Health; LITOE ClinicalTrials.gov number, NCT01065636 .).

Graphical Data Display for Clinical Cardiopulmonary Exercise Testing.

Dumitrescu D, Rosenkranz S

Ann Am Thorac Soc. 2017 May 25. doi: 10.1513/AnnalsATS.201612-955FR. [Epub ahead
of print]

Cardiopulmonary exercise testing is a well-known, valuable tool in the clinical
evaluation of patients with different causes of exercise limitation, and
unexplained dyspnea. A wealth of data is generated by each individual test. This
may be challenging with regard to a comprehensive and reliable interpretation of
an exercise study in a timely manner. An optimized graphical display of exercise
data may substantially help to improve the efficacy and reliability of the
interpretation process. However, there are limited and heterogeneous
recommendations on standardized graphical display in current exercise testing
guidelines. To date, a widely used three-by-three array of specifically arranged
graphical panels known as “Nine Panel Plot” is probably the most common method of
plotting exercise gas exchange data in a standardized way. Furthermore, optimized
scaling of the plots, the use of colours and style elements as well as suitable
averaging methods have to be considered in order to achieve a high level of
quality and reproducibility of the results. Specific plots of key parameters may
allow a fast and reliable visual determination of important diagnostic and
prognostic markers in cardiac and pulmonary diseases.

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

Otto JM; Plumb JOM; Wakeham D; Clissold E; Loughney L; Schmidt W; Montgomery HE; Grocott MPW; Richards T

British Journal Of Anaesthesia [Br J Anaesth] 2017 May 01; Vol. 118 (5), pp. 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 Exercise Testing: Basics of Methodology and Measurements.

Mezzani A; Spa SB,

Annals Of The American Thoracic Society [Ann Am Thorac Soc] 2017 May 16. Date of Electronic Publication: 2017 May 16.

Cardiopulmonary exercise testing adds measurement of ventilation and volume of oxygen uptake and exhaled carbon dioxide to routine physiological and performance parameters obtainable from conventional exercise testing, furnishing an all-round vision of the systems involved in both oxygen transport from air to mitochondria and its utilization during exercise. Peculiarities of cardiopulmonary exercise testing methodology are the use of ramp protocols and calibration procedures for flow meters and gas analyzers. Among the several parameters provided by this technique, peak oxygen uptake, first and second ventilatory thresholds, respiratory exchange ratio, oxygen pulse, slope of ventilation divided by exhaled carbon dioxide relationship, exercise oscillatory ventilation, circulatory power and partial pressure of end-tidal carbon dioxide are among the most relevant in the clinical setting. The choice of parameters to be considered will depend on the indication to cardiopulmonary exercise testing in the individual subject or patient, namely, exercise tolerance assessment, prognostic stratification, training prescription, treatment efficacy evaluation, diagnosis of causes of unexplained exercise tolerance reduction or exercise (patho)physiology evaluation for research purposes. Overall, cardiopulmonary exercise testing is a methodology now widely available and supported by a sound scientific evidence. Despite this, its potential still remains largely underused. Strong efforts and future investigations are needed to address these issues and further promote the use of cardiopulmonary exercise testing in the clinical and research setting.

Chronotropic Incompetence and its Relation to Exercise Intolerance in Chronic Obstructive Pulmonary Disease.

Liu HJ, Guo J, Zhao QH, Wang L, Yang WL, He J, Gong SG, Liu
JM

Am J Med Sci. 2017 Mar;353(3):216-223. doi: 10.1016/j.amjms.2016.12.015. Epub
2016 Dec 21.

BACKGROUND: To study the relationship between chronotropic incompetence (CI) and
disease severity and to assess the effect of CI on exercise capacity in patients
with chronic obstructive pulmonary disease (COPD).
MATERIALS AND METHODS: Arterial blood gas analysis, pulmonary function test and
cardiopulmonary exercise testing were conducted in 60 patients with stable COPD
and 45 healthy volunteers. CI was defined using the chronotropic response index
(CRI = (peak heart rate-resting heart rate) / (220-age-resting heart rate). Based
on CRI, patients with COPD were divided into the normal chronotropic group (n =
23) and CI group (n = 37).
RESULTS: CI was present in 61.7% of the patients with COPD. Exercise capacity
(peak oxygen uptake as percentage of predicted value, peak VO2%pred), peak heart
rate and CRI were significantly lower in patients with COPD than in controls.
However, resting heart rate was significantly higher than in controls. FEV1%pred
and exercise capacity were significantly decreased in the CI group when compared
with those in the normotropic group. There was significant association between
CRI with FEV1%pred and peak VO2%pred. Multivariate regression analysis showed
that CRI and FEV1%pred were independent predictors of exercise capacity in
patients with COPD. A cutoff of 0.74 for the CRI showed a specificity of 94.1% in
predicting patients with a peak VO2%pred < 60%. CONCLUSIONS: CRI was associated with disease severity in patients with COPD. CI may be an important parameter to reflect exercise capacity in patients with COPD.

Scaling the Oxygen Uptake Efficiency Slope for Body Size in Cystic Fibrosis.

Tomlinson OW, Barker AR, Oades PJ, Williams CA.

Med Sci Sports Exerc. 2017 May 9. doi: 10.1249/MSS.0000000000001314. [Epub ahead
of print]

PURPOSE: The aim of this study was to describe the relationship between body size
and the oxygen uptake efficiency slope (OUES) in paediatric patients with cystic
fibrosis (CF) and healthy controls (CON), in order to identify appropriate
scaling procedures to adjust the influence of body size upon OUES.
METHODS: The OUES was derived using maximal and submaximal points from
cardiopulmonary exercise testing in 72 children (36 CF and 36 CON). OUES was
subsequently scaled for stature, body mass (BM) and body surface area (BSA) using
ratio-standard (Y/X) and allometric (Y/X) methods. Pearson’s correlation
coefficients were utilised to determine the relationship between body size and
the OUES.
RESULTS: When scaled using the ratio-standard method, OUES had a significant
positive relationship with stature (r = 0.54, P < 0.001) and BSA (r = 0.25, P = 0.031) and significant negative relationship with BM (r = -0.38, P = 0.016) in the CF group. Combined allometric exponents (b) for CF and CON were: stature 3.00, BM 0.86, BSA 1.40. A significant negative correlation was found between OUES and stature in the CF group when scaled allometrically (r = -0.37, P = 0.027). Non-significant (P > 0.05) correlations for the whole group were found
between OUES and allometrically scaled BM (CF: r = -0.25, CON: r = 0.15) and BSA
(CF r = -0.27, CON r = 0.13).
CONCLUSIONS: Only allometric scaling of either BM or BSA, and not ratio-standard
scaling, successfully eliminates the influence of body size upon OUES. Therefore
this enables a more direct comparison of the oxygen uptake slope between patients
with CF and healthy controls.

Measuring Cardiac Output during Cardiopulmonary Exercise Testing

Vignati C, Cattadori G

Ann Am Thorac Soc. 2017 Apr 25. doi: 10.1513/AnnalsATS.201611-852FR. [Epub ahead
of print]

Cardiac output is a key parameter in the assessment of cardiac function, and its
measurement is fundamental to the diagnosis, treatment, and prognostic evaluation
of all heart diseases. Until recently, cardiac output determination during
exercise had been only possible through invasive methods, which were not
practical in the clinical setting. Since oxygen uptake (V.O2) is cardiac output
times arteriovenous content difference [C(a-v)O2)], evaluation of cardiac output
is usually included its measurement. Because of the difficulty of directly
measuring peak exercise cardiac output, indirect surrogate parameters have been
proposed, but with only modest clinical usefulness. Direct measurement of cardiac
output can now be made by several noninvasive measurements, such as rebreathing
inert gases, impedance cardiology, thoracic bioreactance, estimated continuous
cardiac output (EsCCO) technology, and transthoracic echocardiography coupled to
cardiopulmonary exercise testing allow more definitive results and better
understanding of the underlying physiopathology.

Periodic Breathing during Incremental Exercise.

Agostoni P, Corrà U, Emdin M.

Ann Am Thorac Soc. 2017 Apr 26. doi: 10.1513/AnnalsATS.201701-003FR. [Epub ahead
of print]

Periodic breathing during incremental cardiopulmonary exercise testing is a
regularly recurring waxing and waning of tidal volume due to oscillations in
central respiratory drive. Periodic breathing is a sign of respiratory control
system instability, which may occur at rest or during exercise. The possible
mechanisms responsible of exertional periodic breathing might be related to any
instability of the ventilatory regulation caused by: 1) increased circulatory
delay (i.e., circulation time from the lung to the brain and chemoreceptors, due
to reduced cardiac index leading to delay in information transfer), 2) increase
in controller gain (i.e., increased central and peripheral chemoreceptor
sensitivity to arterial partial pressure of oxygen and of carbon dioxide), or 3)
reduction in system damping (i.e., baroreflex impairment). Periodic breathing
during exercise is observed in several cardiovascular disease populations, but it
is a particularly frequent phenomenon in heart failure due to systolic
dysfunction. The detection of exertional periodic breathing is linked to outcome
and heralds worst prognosis in heart failure, independently of the criteria
adopted for its definition. In small heart failure cohorts, exertional periodic
breathing has been abolished with more than a few dedicated interventions, but
results have not been confirmed, yet. Accordingly, further studies are needed to
define the role of visceral feed-backs in determining periodic breathing during
exercise, as well as to look for specific tools for preventing/treat its
occurrence in heart failure.