Roger Carter

A Preliminary Comparison of Videofluoroscopy of Swallow and Pulse Oximetry in the Identification of Aspiration in Dysphagic Patients

Abstract. Pulse oximetry has recently received attention in the dysphagia literature because of its possible contribution to the management of neurogenic dysphagia. The present study was devised to examine whether pulse oximetry could be exploited to determine episodes of aspiration in patients with known dysphagia of neurologic origin. To this end, pulse oximetry was undertaken in six patients undergoing videofluoroscopic study of swallow. Normal controls also underwent pulse oximetry during feeding. The results indicate that there is no clear-cut relationship between changes in arterial oxygenation and aspiration. However, some support is found for the association between altered arterial oxygenation and oral feeding in dysphagic individuals. Further research in both normals and compromised individuals is needed.

Increased airways reactivity after smoke inhalation

13 fire victims who required treatment after smoke inhalation underwent lung function assessment within 3 days of injury and 3 months later. Initial airways hyperreactivity improved over this period, but FEV1 and airways specific conductance did not change significantly. There was a strong correlation between exposure carboxyhaemoglobin concentration (an indicator of smoke exposure) and initial airways specific conductance (r + 0.79; p = 0.006). Airways obstruction after smoke inhalation in house fires may be more common and more persistent than is generally recognised. Early lung function tests would allow the incidence of pulmonary complications after smoke inhalation and the potential benefits of early use of inhaled antiinflammatory drugs to be assessed.

Diaphragm Ultrasonography as an Alternative to Whole-Body Plethysmography in Pulmonary Function Testing

Objective. Whole‐body plethysmography is a common method of measuring pulmonary function. Although this technique provides a sensitive measure of pulmonary function, it can be problematic and unsuitable in some patients. The development of more accessible techniques would be beneficial. Methods. A prospective study was performed to validate diaphragm ultrasonography as an alternative to whole‐body plethysmography in patients referred for pulmonary function testing. Diaphragm movement and position were assessed by ultrasonography after standard pulmonary function testing using whole‐body plethysmography. Results. A wide range of lung function was observed. Standard lung volumes were as follows: total lung capacity, 5.57 ± 1.31 L, residual volume, 2.27 ± 0.56 L; and vital capacity, 3.30 ± 0.98 L (mean ± SD). The ratio of forced expiratory volume in 1 second to forced vital capacity was calculated as 0.69 ± 0.08. Ultrasonography showed that mean diaphragm excursion values were 11.1 ± 3.8 mm (2‐dimensional), 14.7 ± 4.1 mm during quiet breathing (M‐mode), and 14.8 ± 3.9 mm during a maximal sniff (M‐mode). The velocity of diaphragm movement rose sharply during the sniff maneuver from 15.2 ± 5.8 mm/s during quiet breathing to 104.0 ± 33.4 mm/s. Static 2‐dimensional measures of diaphragm position at the end of quiet inspiration or expiration correlated with standard measures of lung volume on plethysmography (eg, a correlation coefficient of 0.83 was obtained with end inspiration and vital capacity). All measures of diaphragm movement (whether by 2‐dimensional or M‐mode techniques) were poorly correlated with any lung volumes measured. Conclusions. These data suggest that dynamic measurements using diaphragm ultrasonography provide a relatively poor measure of pulmonary function in relation to whole‐body plethysmography.

Measurement of physiological recovery from exacerbation of chronic obstructive pulmonary disease using within-breath forced oscillometry

Background: Within-breath reactance from forced oscillometry estimates resistance via its inspiratory component (Xrs,insp) and flow limitation via its expiratory component (Xrs,exp). Aim: To assess whether reactance can detect recovery from an exacerbation of chronic obstructive pulmonary disease (COPD). Method: 39 subjects with a COPD exacerbation were assessed on three occasions over 6 weeks using post-bronchodilator forced oscillometry, arterial blood gases, spirometry including inspiratory capacity, symptoms and health-related quality of life (HRQOL). Results: Significant improvements were seen in all spirometric variables except the ratio of forced expiratory volume in 1 s (FEV1) to vital capacity, ranging in mean (SEM) size from 11.0 (2.2)% predicted for peak expiratory flow to 12.1 (2.3)% predicted for vital capacity at 6 weeks. There was an associated increase in arterial partial pressure of oxygen (PaO2). There were significant mean (SEM) increases in both Xrs,insp and Xrs,exp (27.4 (6.7)% and 37.1 (10.0)%, respectively) but no change in oscillometry resistance (Rrs) values. Symptom scales and HRQOL scores improved. For most variables, the largest improvement occurred within the first week with spirometry having the best signal-to-noise ratio. Changes in symptoms and HRQOL correlated best with changes in FEV1, PaO2 and Xrs,insp. Conclusions: The physiological changes seen following an exacerbation of COPD comprised both an improvement in operating lung volumes and a reduction in airway resistance. Given the ease with which forced oscillometry can be performed in these subjects, measurements of Xrs,insp and Xrs,exp could be useful for tracking recovery.

Exercise intolerance following heart transplantation: The role of pulmonary diffusing capacity impairment

STUDY OBJECTIVESnAlthough impairment of the diffusing capacity of the lung for carbon monoxide (DLCO) in heart transplant recipients is well-documented, there are limited data on its impact on exercise capacity in these patients. The aim of this study was to determine the effect of DLCO reduction on exercise capacity in heart transplant recipients.nnnDESIGNnDescriptive cohort study.nnnSETTINGnA regional cardiopulmonary transplant center.nnnPARTICIPANTSnTwenty-six heart transplant recipients who were studied before and after transplantation compared with 26 healthy volunteers.nnnMEASUREMENTSnSpirometry and static lung volumes were measured using body plethysmography, DLCO was measured using the single-breath technique, and progressive cardiopulmonary exercise was performed using a bicycle ergometer, continuous transcutaneous blood gas monitoring, and on-line analysis of minute ventilation, oxygen uptake (VO(2)), and carbon dioxide production.nnnRESULTSnBefore transplantation, the mean percent predicted for hemoglobin-corrected DLCO was reduced in patients (73.2%) compared to healthy control subjects (98.8%; p < 0.001) and declined significantly after transplantation (60.1%; p < 0.05). Although the mean maximal symptom-limited VO(2) (VO(2)max) increased after transplantation (increase, 41.3 to 48.6% of predicted; p < 0.05), it remained substantially lower than normal (92.9%; p < 0.001). There was a significant correlation between DLCO and VO(2)max after transplantation (r = 0.61; p = 0.001), but not before transplantation (r = 0.09; p = 0.66). DLCO was also inversely correlated with other respiratory responses to exercise, including the following: the ventilatory response to exercise (r = -0.44; p < 0.05); dead space to tidal volume ratio (r = -43; p < 0.05); and the alveolar-arterial oxygen gradient (r = -0. 45; p < 0.05), but there was no correlation between any of these variables and DLCO before transplantation.nnnCONCLUSIONnDLCO reduction after heart transplantation appears to represent persistent gas exchange impairment and contributes to exercise limitation in heart transplant recipients.

Use of reactance to estimate transpulmonary resistance

This study examines the relationship of respiratory system resistance (Rrs) and reactance (Xrs) measured by forced oscillometry with transpulmonary resistance (RL) measured by oesophageal manometry. Simultaneous forced oscillometry using a single frequency of 5u2005Hz and oesophageal manometry were performed on five asthmatics during bronchoprovocation. The data obtained were used to derive prediction equations for RL from oscillometric parameters, which were tested on a further six asthmatics and 35 nonasthmatic subjects. In the first five asthmatic subjects, RL correlated more strongly with Xrs than with Rrs. In the second set of asthmatics, RL ranged 0.0005–4.57u2005kPa·s·L−1, with a median of 0.21u2005kPa·s·L−1. The RL values predicted from Xrs showed a mean±sd difference of −0.067±0.25u2005kPa·s·L−1 compared with the values measured in this set of patients. Xrs in subjects with other respiratory conditions appeared to follow the same relationship with RL as in asthmatics. Lumped element modelling suggested that the linear relationship between Xrs and RL was a consequence of the increasing contribution of central and upper airway wall shunts as peripheral airway resistance rose, and that this effect was much larger than that due to changes in static elastance. In conclusion, the reactance of the respiratory system can predict transpulmonary resistance more accurately than can the resistance of the respiratory system.

Ventilatory and gas exchange abnormalities on exercise in chronic heart failure

The mechanism of breathlessness on exertion in patients with chronic heart failure are still not fully understood. We therefore investigated the effects of ventilatory and gas exchange abnormalities on exercise capacity in chronic heart failure. Exercise testing was performed in 30 patients with exertional breathlessness due to chronic heart failure and in 30 controls, using continuous transcutaneous blood gas monitoring. Maximal symptom-limited oxygen consumption as (VO2) as a percentage predicted was reduced in patients (45 +/- 10%; mean +/- SD) compared to controls (87 +/- 7). The ventilatory response (minute ventilation/carbon dioxide production (VE/VCO2)) was significantly increased in patients compared to controls (39.9 +/- 7.7 and 25.9 +/- 3.6, respectively). The dead space to tidal volume ratio (VD/VT) was raised in patients compared to controls at rest (0.45 +/- 0.04 vs 0.35 +/- 0.02, respectively) and this persisted on exertion (0.40 +/- 0.05 in patients and 0.20 +/- 0.05 in controls). At maximal symptom-limited exercise, VE/VCO2 was inversely related to the % predicted VO2 in patients, but not in controls (r = -0.62 and r = -0.24, respectively). In patients, VE/VCO2 was significantly correlated with VD/VT at maximum exercise (r = 0.82). Patients with chronic heart failure have a significant degree of wasted ventilation on exertion, which is associated with increased ventilatory response. The increased ventilatory response on exertion appears to contribute to exercise limitation in these patients.

An Observational Investigation of Dysfunctional Breathing and Breathing Control Therapy in a Problem Asthma Clinic

Objectives. Dysfunctional breathing (DB) is recognized as an associated problem in patients with asthma and may be identified by the Nijmegen questionnaire. We conducted an observational study to determine if breathing control therapy (BCT) improved Nijmegen scores or asthma-related quality of life in patients attending a problem asthma clinic. Methods. Nijmegen and Mini Asthma Quality of Life (Mini-AQLQ) questionnaires were completed. Patients with a positive Nijmegen (≥ 23, DB) were referred for BCT and progressive exercise testing (PET) to seek confirmation of dysfunctional breathing. Follow-up questionnaire data were collected at 6 months. Results. A total of 102 patients were studied. The total mean Nijmegen score was 26.4 (range 1–61). Those with a score ≥ 23 (DB group, n = 65, 64%) had significantly lower Mini-AQLQ (mean 2.83) than the non-DB group (n = 37, mean 4.12, 95% CI for difference 0.87, 1.87, p < 0.0001). There was a strong relationship between Nijmegen score and Mini-AQLQ (r = −0.63, p < 0.001) at baseline; 10 of 17 DB patients who completed PET showed inappropriate hyperventilation. Follow-up data, available for Nijmegen and Mini-AQLQ in 44 and 46 patients respectively, showed no significant change in either of these parameters. Conclusions. The strong relationship between Mini-AQLQ and Nijmegen scores and poor relationship between Nijmegen scores and PET-identified inappropriate hyperventilation suggest that a positive Nijmegen score overestimates the presence of dysfunctional breathing in patients with moderate to severe asthma. We found no evidence that a moderate intensity breathing control intervention had any impact on Nijmegen scores or asthma-related quality of life in this patient group.

Clinical InvestigationsTRANSPLANTATIONExercise Intolerance Following Heart Transplantation: The Role of Pulmonary Diffusing Capacity Impairment

STUDY OBJECTIVESnAlthough impairment of the diffusing capacity of the lung for carbon monoxide (DLCO) in heart transplant recipients is well-documented, there are limited data on its impact on exercise capacity in these patients. The aim of this study was to determine the effect of DLCO reduction on exercise capacity in heart transplant recipients.nnnDESIGNnDescriptive cohort study.nnnSETTINGnA regional cardiopulmonary transplant center.nnnPARTICIPANTSnTwenty-six heart transplant recipients who were studied before and after transplantation compared with 26 healthy volunteers.nnnMEASUREMENTSnSpirometry and static lung volumes were measured using body plethysmography, DLCO was measured using the single-breath technique, and progressive cardiopulmonary exercise was performed using a bicycle ergometer, continuous transcutaneous blood gas monitoring, and on-line analysis of minute ventilation, oxygen uptake (VO(2)), and carbon dioxide production.nnnRESULTSnBefore transplantation, the mean percent predicted for hemoglobin-corrected DLCO was reduced in patients (73.2%) compared to healthy control subjects (98.8%; p < 0.001) and declined significantly after transplantation (60.1%; p < 0.05). Although the mean maximal symptom-limited VO(2) (VO(2)max) increased after transplantation (increase, 41.3 to 48.6% of predicted; p < 0.05), it remained substantially lower than normal (92.9%; p < 0.001). There was a significant correlation between DLCO and VO(2)max after transplantation (r = 0.61; p = 0.001), but not before transplantation (r = 0.09; p = 0.66). DLCO was also inversely correlated with other respiratory responses to exercise, including the following: the ventilatory response to exercise (r = -0.44; p < 0.05); dead space to tidal volume ratio (r = -43; p < 0.05); and the alveolar-arterial oxygen gradient (r = -0. 45; p < 0.05), but there was no correlation between any of these variables and DLCO before transplantation.nnnCONCLUSIONnDLCO reduction after heart transplantation appears to represent persistent gas exchange impairment and contributes to exercise limitation in heart transplant recipients.

Pre‐operative cardiopulmonary exercise testing predicts adverse post‐operative events and non‐progression to adjuvant therapy after major pancreatic surgery

BACKGROUNDnSurgery followed by chemotherapy is the primary modality of cure for patients with resectable pancreatic cancer but is associated with significant morbidity. The aim of the present study was to evaluate the role of cardiopulmonary exercise testing (CPET) in predicting post-operative adverse events and fitness for chemotherapy after major pancreatic surgery.nnnMETHODSnPatients who underwent a pancreaticoduodenectomy or total pancreatectomy for pancreatic head lesions and had undergone pre-operative CPET were included in this retrospective study. Data on patient demographics, comorbidity and results of pre-operative evaluation were collected. Post-operative adverse events, hospital stay and receipt of adjuvant therapy were outcome measures.nnnRESULTSnOne hundred patients were included. Patients with an anaerobic threshold less than 10u2009ml/kg/min had a significantly greater incidence of a post-operative pancreatic fistula [International Study Group for Pancreatic Surgery (ISGPS) Grades A-C, 35.4% versus 16%, P = 0.028] and major intra-abdominal abscesses [Clavien-Dindo (CD) Grades III-V, 22.4% versus 7.8%, P = 0.042] and were less likely to receive adjuvant therapy [hazard ratio (HR) 6.30, 95% confidence interval (CI) 1.25-31.75, P = 0.026]. A low anaerobic threshold was also associated with a prolonged hospital stay (median 20 versus 14 days, P = 0.005) but not with other adverse events.nnnDISCUSSIONnCPET predicts a post-operative pancreatic fistula, major intra-abdominal abscesses as well as length of hospital stay after major pancreatic surgery. Patients with a low anaerobic threshold are less likely to receive adjuvant therapy.