ROLE OF EXERCISE STRESS TESTING IN PREOPERATIVE EVALUATION OF PATIENTS FOR LUNG RESECTION

Preoperative Walking Capacity Indirectly Relates to Decreased Postoperative Complications in Patients with Gastrointestinal Cancer

Objectives:

Postoperative complications (PCs) in patients with gastrointestinal cancer (GIC) lead to reduced lifespan and poor quality of life. The aim of this study was to investigate the correlation between preoperative exercise-related factors, together with other contributory factors, and the frequency of PCs in patients with GIC.

Methods:

This was a cross-sectional, three-institution study. We enrolled 299 patients who were scheduled for elective surgery for GIC (182 men and 117 women; age, 65.7 ± 11.0 years). PCs were graded using the Clavien–Dindo classification based on the medical records 1 month postoperatively. Exercise-related factors (the skeletal muscle index, the isometric knee extension torque, and the 6-min walk test [6 MWT] distance) were measured before surgery. Based on previous studies of factors contributing to complications, data on age, sex, clinical cancer stage, comorbidities, neoadjuvant therapy, type of surgery, surgery duration, blood loss, blood transfusion, laboratory data, respiratory function, body mass index, and visceral fat area were collected.

Results:

The frequency of PCs was positively correlated with surgery duration (β=0.427) and C-reactive protein (CRP) level on postoperative day 3 (β=0.189). The 6 MWT was negatively correlated with the frequency of PCs through CRP level on postoperative day 3 (β=–0.035). This model demonstrated an acceptable fit to the data (goodness-of-fit index, 0.979; adjusted goodness-of-fit index, 0.936; comparative fit index, 0.944; and root mean square error of approximation, 0.076).

Conclusions:

Preoperative walking capacity was correlated with PCs in patients undergoing GIC surgery. Prevention of PCs in patients with GIC requires the monitoring of both surgical parameters and postoperative inflammation.

Onset factors of infective and non-infective complications in perioperative gastrointestinal cancer patients

[Purpose] This study aimed to examine the causes of post-surgical infective and non-infective complications and to examine the possibility of physical therapy for preventing postoperative complications in gastrointestinal cancer patients. [Participants and Methods] The study participants were 119 perioperative gastrointestinal cancer patients [69 males and 50 females, aged 62.2 ± 11.2 years (mean ± standard deviation)] classified into three groups according to whether they had infective complications, non-infective complications, or the absence of complications. Data on onset factors for complications, basic information, surgical information, biochemical data, respiratory function, physical function, physique, and body composition were collected from a previous study. [Results] In the group with onset factors of infective complications, blood loss, the C-reactive protein level on the third postoperative day, and the forced expiratory volume % in 1 second were found to be significant explanatory variables. In the group with onset factors of non-infective complications, surgical time was detected as a significant explanatory variable. [Conclusion] In gastrointestinal cancer patients, surgical information affected the onset of infective and non-infective complications. However, only infective complications had the onset factors of postoperative immune response and preoperative respiratory function. Preoperative physical therapy may be an option for the prevention of postoperative complications in gastrointestinal cancer patients.

Physiology and clinical applications of cardiopulmonary exercise testing in lung cancer surgery

Cardiopulmonary exercise testing (CPET) permits measurement of oxygen uptake (Vo2), an indicator of overall cardiopulmonary fitness and a useful measurement in the assessment of operative risk for lung cancer patients. The evidence supporting the use of CPET in pre-operative assessment of the lung cancer surgery patient is examined. CPET methodology and limitations, as well as alternatives to CPET for risk assessment are discussed.

Pulmonary pathophysiology and lung mechanics in anesthesiology: a case-based overview

Anesthesia, surgical requirements, and patients' unique pathophysiology all combine to make the accumulated knowledge of respiratory physiology and lung mechanics vital in patient management. This article take a case-based approach to discuss how the complex interactions between anesthesia, surgery, and patient disease affect patient care with respect to pulmonary pathophysiology and clinical decision making. Two disparate scenarios are examined: a patient with chronic obstructive pulmonary disease undergoing a lung resection, and a patient with coronary artery disease undergoing cardiopulmonary bypass. The impacts of important concepts in pulmonary physiology and respiratory mechanics on clinical management decisions are discussed.

Novel portable device measures preoperative patient metabolic gas exchange

BACKGROUND

Indirect calorimetry (IC), the measurement of airway CO2 elimination (VCO2), O2 [corrected] uptake (VO2) [corrected], and respiratory exchange ratio (RER = VCO2/VO2), is a noninvasive modality for the assessment of body metabolism. In anesthesia, IC can signal critical events and onset of acute metabolic derangements. We have previously demonstrated the accuracy and precision of a new IC measurement system designed for mechanically ventilated patients, comprised of a new clinical bymixer, fast response humidity and temperature sensor, and a flowmeter. However, measurement of IC during spontaneous breathing is challenging because of unstable tidal volume, frequency, and functional residual capacity (FRC).

METHODS

A new device for IC measurements, designed specifically for spontaneous breathing, was validated against a metabolic lung simulator bench setup. In a second study, the same device was used to conduct preoperative measurements of VCO2 and VO2 in 15 patients.

RESULTS

Our measurements showed excellent correlation and agreement with metabolic lung simulator values: The average (+/-SD) percent error for airway VCO2 was -4.7% +/- 3.31%; the average (+/-SD) percent error for airway VO2 was -0.30% +/- 5.25%. Average values of VCO2 and VO2 in the patient study (3.01 +/- 0.56 and 3.44 +/- 0.69 mL x kg(-1) x min(-1), respectively) were in agreement with previously reported values.

CONCLUSION

We have shown that the new, portable bymixer-flow device, using a bymixer and a fast response humidity sensor, provided accurate and convenient bedside measurement of VCO2 and VO2. We believe that it can contribute in the future to preoperative assessment and baseline reference value for perioperative management.

Pulmonary function tests in preoperative pulmonary evaluation

Pulmonary function testing (PFT) has been used to evaluate the risk for postoperative complications since the 1950s. PFT including spirometry, lung volumes, diffusing capacity, oximetry, and arterial blood gases has been used to assess the postoperative risk of lung resection. In selected cases, additional evaluation may include radionuclide lung scanning, exercise testing, invasive pulmonary hemodynamic measurements, and risk stratification analysis. A new index, predicted postoperative product (PPP), was found to have strong predictive ability for mortality. We defined a new useful index, measured product (MP), to predict postoperative complications; MP had similar advantages of PPP. Since diffusing capacity at rest has been shown to be a good predictor of postoperative complications following lung resection, and since exercise testing has been also useful in preoperative evaluation prior to lung resection, we reasoned that evaluation of the effect of exercise on diffusing capacity would be helpful to evaluate the ability of the pulmonary capillary bed to expand and increase its capacity to transfer gas during exercise.

Clinical exercise testing

Clinical exercise testing is increasingly being utilized in clinical practice because of the valuable, often unique information that it provides in patient diagnosis and management. This is also due to a growing awareness that resting cardiopulmonary measurements provide an unreliable estimate of functional capacity. A continuum of exercise testing modalities for functional evaluation from "low tech" to "high tech" will be discussed. These include the six minute walk test, shuttle walk test, exercise induced bronchoconstriction test, cardiac stress test, and cardiopulmonary exercise testing. The main focus of this article will be cardiopulmonary exercise testing including indications, important measurements, salient methodological considerations, and interpretation.

Postoperative pulmonary complications

Patients undergoing elective surgery first need to be screened for operative risks by reviewing factors that relate to the patient and factors that relate to the procedure they are undergoing. The identification of high-risk patients undergoing high-risk procedures may be aided by reviewing the following factors: the presence of symptomatic lung disease, smoking, obesity, abnormal blood gas values, spirometry, and presence of sleep apnea. The more risk factors a patient has, the more likely the patient will develop postoperative complications. Further risk stratification may be accomplished by means of exercise testing, either through formal cardiopulmonary exercise testing or through symptom-limited stair climbing. When high-risk patients are identified, preoperative therapy aimed at reducing overall postoperative morbidity and mortality may help decrease the risk to a minimum.

Role of CO diffusing capacity during exercise in the preoperative evaluation for lung resection

We conducted a prospective study to evaluate whether lack of an adequate increase in diffusing capacity for carbon monoxide (DL(CO)) during exercise is associated with a greater postoperative complication rate after lung resection. We used the three-equation method (3EQ-DL(CO)), a modification of the single breath DL(CO) technique to determine DL(CO) during exercise in 57 patients undergoing lung resection at Vancouver General Hospital from October 1998 to May 1999. 3EQ-DL(CO) was determined during steady-state exercise at 35% and 70% of the maximal workload reached in a progressive exercise test. Maximal oxygen uptake (VO(2)max), DL(CO) at rest, and the increase in DL(CO) during exercise were compared in relation to postoperative complications. Patients with complications had lower resting values of DL(CO) (R-DL(CO)), a smaller increase in DL(CO) from rest to 70% of maximal workload expressed as a percent of the predicted DL(CO) at rest ([70% - R]-DL(CO)%), and a lower VO(2)max than did patients without complications. Results suggested that (70% - R)-DL(CO)% was the best preoperative predictor of postoperative complications; a cutoff limit of 10% was the best index to identify complications, yielding a complication rate of 100% in patients with (70% - R)-DL(CO)% < 10% as compared with a complication rate of 10% in patients with (70% - R)-DL(CO)% >/= 10% (sensitivity = 78%, specificity = 100%). Patients who do not increase their DL(CO) sufficiently during exercise ([70% - R]-DL(CO)% < 10%) have a greater complication rate after lung resection.

Prediction of post-operative cardiopulmonary function using perfusion scintigraphy in patients with bronchogenic carcinoma

Both ventilation and perfusion scintigraphy are accurate predictors of post-operative ventilatory function. Previous attempts to predict post-operative exercise capacity after lung resection using radioisotope scintigraphy are few and results are conflicting. We studied 32 patients before and 6 months after pulmonary resection for bronchogenic carcinoma to assess the value of lung perfusion scintigraphy for the prediction of post-operative forced lung volumes and parameters on maximum exercise, including maximum ventilation and maximum oxygen uptake. Nine patients were lost to follow-up, and these patients differed from the reinvestigated patients only in the staging of the pulmonary carcinoma and not in preoperative lung function or exercise capacity. We found a clear relationship between the values predicted from a preoperative perfusion scintigraphy, spirometry and a maximum exercise study and the observed values measured 6 months post-operatively. The method underestimated the post-operative values of both spirometric and exercise measurements, especially in the higher range. Only in a few cases were the post-operative observed values less than the predicted values, and in these cases the difference was without clinical significance. Unexpected post-operative respiratory insufficiency was not observed. In conclusion, in patients in whom a pulmonary resection was performed, not only the post-operative spirometric values, but also the more functional related maximum exercise data can be predicted through the knowledge of a preoperative perfusion scintigraphy.

Clinical applications of cardiopulmonary exercise testing

Noninvasive measurement of metabolic and cardiorespiratory variables can be readily obtained using computerized systems as part of exercise testing of patients on a cycle ergometer or treadmill. The major indications for CPEX are: to assess exercise-related symptoms, especially dyspnea and chest pain; to measure exercise capacity including acceptability of patients with end-stage heart disease for cardiac transplantation; to evaluate for impairment/disability; to establish safety and guidelines for exercise training; and to assess response to specific therapy. As most patients with chronic cardiorespiratory disorders reduce their activities and consequently become deconditioned, CPEX should be considered as part of the initial evaluation. The results of CPEX should enable the physician to understand the reason(s) for the patient's exercise limitation and usually support the recommendation that the patient participate in a reconditioning or rehabilitation program. Should expired gases be measured as routine for all exercise tests? The use of CPEX depends on the clinical question. If the question is, "Does the patient have ischemic heart disease?", then a standard "cardiac stress test" is adequate. If the clinical question is, "Why is the individual limited in exercise ability?" or "Why is a patient breathless with activities?", then comprehensive CPEX is indicated. One important issue relating to CPEX is cost effectiveness. Do the results of CPEX justify the expense? There are little if any data to answer this question. However, if CPEX can establish a specific diagnosis, exclude significant heart disease, estimate work capacity, and/or provide guidelines for prescription of exercise intensity, this information may be invaluable to the individual patient and to the health-care provider. It is possible that CPEX may answer a specific clinical question and thereby actually eliminate the need and reduce the cost of additional expensive diagnostic tests. A prospective assessment of the cost effectiveness of CPEX will be important for select clinical problems.