Prevalence and outcome of pulmonary fibrosis in microscopic polyangiitis.

We sought to determine the type of pulmonary involvement in microscopic polyangiitis (MPA), primarily focusing on pulmonary fibrosis (PF), its prevalence, temporal relationship with other disease manifestations and outcome. 33 patients (16 males) with biopsy proven perinuclear anti-neutrophilic cytoplasmic antibody-positive MPA (age 63.5 yrs) participated in the study. Pulmonary involvement was assessed using standard methods, including radiographic imaging (chest radiographs and high-resolution computed tomography), pulmonary function testing, bronchoscopy and bronchoalveolar lavage, and, if indicated, lung biopsy. All-cause mortality was analysed by the Kaplan-Meier method and was compared between MPA patients with and without PF. At the time of diagnosis, renal involvement was detected in all patients, with renal biopsies being consistent with segmental necrotising glomerulonephritis in all patients. The most common respiratory symptom was haemoptysis, which was found in nine (27%) patients. PF was present in 12 (36%) patients at the time of diagnosis, whereas one patient developed PF while on therapy approximately 10 yrs after disease diagnosis. In seven patients with PF, respiratory symptoms related to fibrosis preceded other disease manifestations by a median (range) period of 13 (5-120) months. Patients were followed up for a period of 38+/-30 months. Presence of PF was associated with increased mortality (p = 0.02), with six deaths occurring in the fibrotic group and one in the nonfibrotic group. In the fibrotic group most deaths were related to PF. PF occurs frequently in MPA, may precede other disease manifestations by a variable length of time and has a poor prognosis.

Myocardial performance and aortic elasticity are impaired in patients with ankylosing spondylitis.

OBJECTIVE: To measure aortic stiffness and global left ventricular (LV) function in patients with ankylosing spondylitis (AS) and no clinical evidence of heart disease. METHODS: Fifty-seven consecutive patients with AS (54 males, three females, mean age 41.78+/-10.02 years) without clinical evidence of cardiac involvement and 78 healthy subjects (73 males, five females, mean age 39.92+/-9.11 years) underwent complete echocardiographic study. Aortic stiffness was determined non-invasively by aortic distensibility (AoD) and the global LV function was evaluated by the myocardial performance index (the Tei index). RESULTS: AoD in patients with AS [(2.21+/-0.24)x10(-6) cm(2) dyn(-1)] was decreased compared to controls [(2.58+/-0.19) )x10(-6) cm(2) dyn(-1), p<0.01], confirming that aortic stiffness is increased in AS. The LV Tei index was significantly increased in the patient group compared to the control group (0.392+/-0.031 vs. 0.370+/-0.034, p<0.01). The ejection fraction (EF) did not differ between the two groups (p>0.05). In multivariate linear regression analysis, AoD was significantly associated with the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and LV isovolumic relaxation time (IVRT) whereas the LV Tei index was associated with BASDAI and the LV mass index. CONCLUSIONS: Patients with AS and no clinical evidence of cardiac disease have increased stiffness of the aorta and decreased global myocardial performance and both of these abnormal measurements correlate with disease activity. The abnormal Tei index may reflect an early manifestation of cardiac dysfunction in these patients.

Thoracoabdominal motion in ankylosing spondylitis: association with standardised clinical measures and response to therapy.

OBJECTIVES: To assess the relationship between thoracoabdominal motion during quiet breathing and standardised indices of disease severity in patients with ankylosing spondylitis (AS); also to evaluate whether thoracoabdominal motion improves after institution of biological agents in these patients. METHODS: Displacement of the rib cage (RC) and abdomen (Abd) during quiet breathing in the sitting, standing and supine position were recorded by impedance plethysmography in 60 patients (mean (SD) age 41 (10) years, 56 men) and 21 healthy men (mean (SD) 36 (7) years). x-y plots of RC versus Abd displacement during quiet breathing were constructed, and the angle of the slope of the RC-Abd loop was calculated and averaged for five consecutive breaths. In 13 patients treated with anti-tumour necrosis factor alpha (TNFalpha), measurements were made before and at 3, 6 and 12 months after the start of treatment. RESULTS: In the entire AS group, the angle of the slope of the RC-Abd loop correlated with Bath Ankylosing Spondylitis Functional Index (BASFI) in the sitting (R = -0.50, p<0.0001), standing (R = -0.36, p = 0.004) and supine (R = -0.47, p = 0.0001) position, but not with Bath Ankylosing Spondylitis Disease Activity (BASDAI), Bath Ankylosing Spondylitis Metrology Index (BASMI) or the modified Schober's test. In 13 patients treated with anti-TNFalpha, the angle of the RC-Abd slope improved significantly (35-69% over baseline at 3 months) in all body positions and in a nearly parallel fashion with the improvements in standardised clinical measurements. CONCLUSIONS: The pattern of thoracoabdominal motion during quiet breathing correlates with BASFI, and its response to anti-TNFalpha treatment is large. This variable may be an appropriate target for evaluating potential usefulness in monitoring thoracic spine involvement and response to treatment in AS.

Occult connective tissue diseases mimicking idiopathic interstitial pneumonias.

In patients with interstitial lung disease (ILD), the diagnosis of idiopathic interstitial pneumonia is usually made after excluding, among other conditions, connective tissue diseases (CTDs). Although in most patients with a CTD and respiratory symptoms, the systemic nature of the disease is obvious, the ILD-related manifestations in CTDs may often dominate the clinical picture or precede systemic findings and thus mimic idiopathic interstitial pneumonia. With the exception of systemic lupus erythematosus, all CTDs may imitate chronic idiopathic interstitial pneumonias. In this setting, clues to an underlying CTD may be entirely absent or include subtle findings from various systems, including skin, vascular and musculoskeletal system or internal organs. Since nonspecific interstitial pneumonia is a relatively frequent histological pattern in CTDs, biopsy reports of nonspecific interstitial pneumonia should also prompt a search for an underlying CTD. Ultimately, diagnosis of a CTD requires confirmation with immunological testing; interpretation of the various laboratory tests should always be carried out in conjunction with clinical findings. The present article reviews specific clinical aspects of connective tissue disease-related interstitial lung disease that may help differentiate it from idiopathic interstitial pneumonia, especially when interstitial lung disease is the predominant or sole manifestation of an occult connective tissue disease.

Determinants of pulmonary function improvement in patients with scleroderma and interstitial lung disease.

BACKGROUND: In patients with scleroderma-related interstitial lung disease (ILD), improvements of pulmonary function have been reported after treatment with cyclophosphamide (CYC) alone or CYC and high-dose steroids. The study objective was to identify therapeutic regimen that alone or in combination with laboratory or clinical characteristics were associated with pulmonary function improvement in these patients. METHODS: Scleroderma patients with ILD and serial pulmonary function measurements were retrospectively analyzed. We recorded forced vital capacity (FVC, % predicted), diffusion capacity (DLCO, % predicted), type of therapy, and various clinical and laboratory parameters. Treatment with IV CYC was recorded as cumulative dose (grams) and treatment with steroids as high or low dose; outcome was defined as a sustained increase in FVC (% predicted) >or= 10 points. RESULTS: Of the 59 patients who were included in the study, 29 (49 %) patients received IV CYC (cumulative dose 13.9 +/-6.2, range 5.2-26.2 gr) for 3.3 +/- 2.4 years (range 5-60 months). Eighteen out of 59 (30 %) patients received high-dose prednisolone and 41 (70 %) received low-dose prednisolone. In an ordinal logistic model, patients receiving > 12 gr of CYC were 6 times more likely to improve FVC than to decrease or maintain FVC, compared to those who did not receive CYC (p = 0.02). In multivariate analysis, the effect of high dosage CYC on FVC persisted (OR 10.82, p = 0.02). Steroid dosage (high or low) was not associated with FVC improvement (p < 0.05). CONCLUSION: In patients with scleroderma and ILD, treatment with CYC is the only variable that is independently associated with pulmonary function improvement and that prolonged (> 1 year) CYC therapy increases the probability of pulmonary function improvement more than shorter CYC courses.

Candiduria in intensive care units: association with heavy colonization and candidaemia.

Candiduria is increasingly detected in intensive care unit (ICU) patients and often coexists with candidal colonization at other anatomical sites. Studies involving surgical and medical ICU patients have consistently reported a relationship between candiduria and heavy colonization. This suggests that candiduria could be considered as a marker for heavy colonization. Risk factors that predispose to heavy colonization are generally similar to those predisposing to candidaemia. Candiduria in ICU patients is characterized by a high mortality, largely through a significant relationship with candidaemia, which in some patients may reach 50%. Therapeutic interventions should be strongly considered in the critically ill patient who presents with candiduria and concurrent clinical risk factors predisposing to dissemination.

Respiratory muscle performance with stretch-shortening cycle manoeuvres: maximal inspiratory pressure-flow curves.

AIM: To test the hypothesis that the maximal inspiratory muscle (IM) performance, as assessed by the maximal IM pressure-flow relationship, is enhanced with the stretch-shortening cycle (SSC). METHODS: Maximal inspiratory flow-pressure curves were measured in 12 healthy volunteers (35 +/- 6 years) during maximal single efforts through a range of graded resistors (4-, 6-, and 8-mm diameter orifices), against an occluded airway, and with a minimal load (wide-open resistor). Maximal inspiratory efforts were initiated at a volume near residual lung volume (RV). The subjects exhaled to RV using slow (S) or fast (F) manoeuvres. With the S manoeuvre, they exhaled slowly to RV and held the breath at RV for about 4 s prior to maximal inspiration. With the F manoeuvre, they exhaled rapidly to RV and immediately inhaled maximally without a post-expiratory hold; a strategy designed to enhance inspiratory pressure via the SSC. RESULTS: The maximal inspiratory pressure-flow relationship was linear with the S and F manoeuvres (r2 = 0.88 for S and r2 = 0.88 for F manoeuvre, P < 0.0005 in all subjects). With the F manoeuvre, the pressure-flow relationship shifted to the right in a parallel fashion and the calculated maximal power increased by approximately 10% (P < 0.05) over that calculated with the S manoeuvre. CONCLUSION: The maximal inspiratory pressure-flow capacity can be enhanced with SSC manoeuvres in a manner analogous to increases in the force-velocity relationship with SSC reported for skeletal muscles.

Pattern of breathing during progressive exercise in chronic heart failure.

This descriptive study analyzed serial, individual changes in the exercise pattern of breathing (POB) of patients with stable chronic heart failure (CHF). Twenty-two CHF patients underwent maximal, symptom-limited cardiopulmonary exercise test on a treadmill. Minute ventilation (VE), tidal volume (VT), breathing frequency (f), the ventilatory equivalent for carbon dioxide (VE/VCO2) and estimated dead-space to tidal volume ratio (VD/VT) were continuously recorded. The VE/VCO2 slope was calculated in every subject as the slope of the regression line relating VE to VCO2 during exercising testing. Pattern of breathing was investigated by constructing the individual VT-f relationship for each patient separately. In 16 (73%) patients (group 1), the VT-f plot was initially linear, but subsequently exhibited an inflection point at which VT stopped increasing with further increases in f. In six (27%) patients (group 2) no inflection point was evident on the VT-f relation; in four of these patients the VT-f relation remained linear but shifted to the right throughout testing, and two patients decreased VT before peak exercise achieving high breathing frequencies. Comparing group 1 to group 2 patients, they had higher VEmax (68+/-23 vs. 44+/-10 l/min, P=0.02) and VO2max (17+/-5 vs. 12+/-3 ml/min/kg, P=0.01). In contrast, the two groups did not differ in terms of age, weight, height, diagnosis, ejection fraction or VE/VCO2 slope. In conclusion, patients with CHF adopt variable breathing patterns during exercise; specific patterns are associated with greater impairment in functional capacity.

Functional status and quality of life in long-term survivors of cardiac arrest after cardiac surgery.

OBJECTIVE: To assess long-term survival, functional status, and quality of life in patients who experienced cardiac arrest after cardiac surgery. DESIGN: Prospective, observational study. SETTING: An 18-bed, adult cardiac surgery intensive care unit in a tertiary teaching center. PATIENTS: Twenty-nine cardiac surgery patients who suffered an unexpected cardiac arrest in the immediate postoperative period. INTERVENTIONS: The New York Heart Association classification and a questionnaire based on the Nottingham Health Profile were used to evaluate functional status and quality of life 4 yrs after hospital discharge. MEASUREMENTS AND MAIN RESULTS: Of the 29 patients who experienced cardiac arrest during the first 24 hrs after cardiac surgery, 27 patients (93%) were successfully resuscitated and 23 patients (79%) survived to hospital discharge. Evaluation 4 yrs postdischarge showed that, of the 29 patients, 16 patients (55%) were still alive (long-term survivors). Functional status assessment of long-term survivors revealed that 12 patients (75%) were grouped in New York Heart Association class I, 3 patients (19%) in class II, and 1 patient (6%) in class III. None of them had a neurologic deficit. They all were living independently at home, without need of any nursing care. No patient reported any abnormal emotional reactions, and six patients (38%) had mild sleep disturbances, such as early awaking. Regarding activities of daily living, 20% returned to work, 94% were able to look after their home, 96% had a social life, 63% were sexually active, 81% were involved in their hobbies, and 75% had gone on holidays. CONCLUSIONS: Cardiac surgery patients who experience an unexpected cardiac arrest in the immediate postoperative period have a 55% chance of being alive 4 yrs postdischarge. The majority of these long-term survivors has a good outcome with respect to functional status and quality of life.

Correcting static intrinsic positive end-expiratory pressure for expiratory muscle contraction. Validation of a new method.

We have recently shown (Eur. Respir. J. 1997;10:522-529) that in spontaneously breathing and actively expiring patients, static intrinsic positive end-expiratory pressure (PEEPi,st) can be corrected for expiratory muscle contraction by subtracting the average expiratory rise in gastric pressure (Pga,exp rise), calculated from three breaths just prior to an airway occlusion, from the end-expiratory airway pressure (Paw) of the first occluded inspiratory effort (PEEPi,st avg). However, since in some patients there is substantial variability in the intensity of expiratory muscle activity and hence in Pga,exp rise, this method may be inaccurate because the Pga,exp rise of breaths preceding airway occlusion may differ from that of the first postocclusion breath. In the present study, we introduced a new method consisting of synchronous subtraction of Pga,exp rise from Paw, both occurring during airway occlusion (PEEPi,st sub). PEEPi,st sub and PEEPi,st avg were each compared with the reference PEEPi,st (PEEPi,st ref), which was obtained during muscular paralysis and simulation of the spontaneous breathing pattern by the ventilator. We found that, in 25 critically ill patients, PEEPi,st sub (mean +/- SD, 5.3 +/- 2.6 cm H(2)O) was nearly identical to PEEPi,st ref (5.4 +/- 2.4 cm H(2)O). Their mean difference was -0.06 cm H(2)O with limits of agreement -0.96 to 0.84 cm H(2)O, indicating a strong agreement between these methods. In contrast, mean difference of PEEPi,st avg and PEEPi,st ref was 0.73 cm H(2)O with limits of agreement -3.97 to 5.43 cm H(2)O, indicating lack of agreement. Coefficient of variation of Pga,exp rise was 14.3 +/- 7.2% (range, 5.2 to 28.3%). There was a good correlation between the coefficient of variation of Pga,exp rise and the difference between PEEPi,st avg and PEEPi,st ref (r = 0.909; p < 0.001). We conclude that PEEPi,st can be accurately measured in spontaneously breathing patients by synchronous subtraction of Pga,exp rise from Paw during airway occlusion.

Respiratory function in patients with thalassaemia and iron overload.

Iron deposition in the respiratory system has been proposed as a potential cause of the ventilatory restrictive impairment seen in patients with thalassaemia major (TM) and iron overload. In this study, magnetic resonance imaging (MRI) measurements of the liver (T2 relaxation time) were used as a surrogate index of total body iron burden and the extent to which these measurements correlated with total lung capacity (TLC) in patients with TM was examined. Twenty-one patients (aged 25+/-5 yrs) with TM participated in the study. Standard pulmonary function tests were undertaken and the T2 relaxation time of the liver was measured in all patients. Ventilatory restrictive impairment (mean TLC 74+/-11 (SD)% predicted) was the most common abnormality found in 71% of TM patients. There was no correlation between TLC (% pred) and T2 relaxation time (r=0.06, p=0.78). T2 relaxation time correlated weakly with average serum ferritin levels (r=-0.56, p=0.008). In conclusion, the data do not support the notion that the restrictive impairment in patients with thalassaemia major and iron overload is related to iron deposition in the respiratory system.

Pulmonary function and respiratory muscle strength in chronic heart failure: comparison between ischaemic and idiopathic dilated cardiomyopathy.

OBJECTIVE: To compare pulmonary function and respiratory muscle strength in patients with ischaemic and idiopathic dilated cardiomyopathy, well matched for indices of heart failure. METHODS: The study involved 30 patients with ischaemic cardiomyopathy and 30 with idiopathic dilated cardiomyopathy. The groups were well matched for age, weight, and clinical severity of cardiac dysfunction as assessed by ejection fraction and the New York Heart Association functional class. There were more smokers in the ischaemic group (p < 0.05), but indices of pulmonary function were comparable. RESULTS: Mean (SD) maximum static inspiratory pressure was lower in dilated cardiomyopathy than in ischaemic cardiomyopathy (73 (20) v 84 (22) cm H2O, p < 0.05), as was the maximum static expiratory pressure (90 (20) v 104 (21) cm H2O, p < 0.05). CONCLUSIONS: For a given degree of cardiac dysfunction, the respiratory muscles are weaker in patients with idiopathic dilated cardiomyopathy than in those with ischaemic cardiomyopathy.

Inspiratory muscle adaptations following pressure or flow training in humans.

Skeletal muscle adapts differently to training with high forces or with high velocities. The effects of these disparate training protocols on the inspiratory muscles were investigated in ten healthy volunteers. Five subjects trained using high force (pressure) loads (pressure trainers) and five trained using high velocity (flow) loads (flow trainers). Pressure training entailed performing 30 maximal static inspiratory efforts against a closed airway. Flow training entailed performing 30 sets of three maximal dynamic inspiratory efforts against a minimal resistance. Training was supervised and carried out 5 days a week for 6 weeks. Inspiratory flow rates and oesophageal pressure-time curves were measured before and after training. Peak inspiratory pressures during maximal static and dynamic efforts and peak flows during the maximal dynamic efforts were calculated. The time-to-peak pressure and rate of rise in peak pressure during maximal static and dynamic manoeuvres were also calculated before and following training. Maximal static pressure increased in the pressure training group and maximal dynamic pressure increased in the flow training group. Both groups increased the rate of pressure production (dP/dt) during their respective maximal efforts. The post-training decrease in time-to-peak pressure was proportionately greater in the flow trainers than in the pressure trainers. The differences in time-to-peak pressure between the two groups were consistent with the different effects of force and velocity training on the time-to-peak tension of skeletal muscle.

Contribution of lung function to exercise capacity in patients with chronic heart failure.

BACKGROUND: The importance of exercise capacity as an indicator of prognosis in patients with heart disease is well recognized. However, factors contributing to exercise limitation in such patients have not been fully characterized and in particular, the role of lung function in determining exercise capacity has not been extensively investigated. OBJECTIVE: To examine the extent to which pulmonary function and respiratory muscle strength indices predict exercise performance in patients with moderate to severe heart failure. METHODS: Fifty stable heart failure patients underwent a maximal symptom-limited cardiopulmonary exercise test on a treadmill to determine maximum oxygen consumption (VO2max), pulmonary function tests and maximum inspiratory (PImax) and expiratory (PEmax) pressure measurement. RESULTS: In univariate analysis, VO2max correlated with forced vital capacity (r = 0.35, p = 0.01), forced expiratory volume in 1 s (r = 0.45, p = 0.001), FEV1/FVC ratio (r = 0.37, p = 0.009), maximal midexpiratory flow rate (FEF25-75, r = 0. 47, p < 0.001), and PImax (r = 0.46, p = 0.001), but not with total lung capacity, diffusion capacity or PEmax. In stepwise linear regression analysis, FEF25-75 and PImax were shown to be independently related to VO2max, with a combined r and r2 value of 0. 56 and 0.32, respectively. CONCLUSIONS: Lung function indices overall accounted for only approximately 30% of the variance in maximum exercise capacity observed in heart failure patients. The mechanism(s) by which these variables could set exercise limitation in heart failure awaits further investigation.

Effects of different expiratory maneuvers on inspiratory muscle force output.

We assessed the effects of two different expiratory maneuvers (fast [F] or slow [S]) on the ability of normal subjects (n = 12, age 35 +/- 6 yr) to generate maximal inspiratory pressures and maximal inspiratory flows near residual volume (RV). With the F maneuver, the subject exhaled rapidly to RV and immediately performed a maximal inspiratory effort, whereas with the S maneuver the subject exhaled slowly to RV, paused for 4 to 6 s at RV, and then inspired forcefully. Maximal static inspiratory pressure against an occluded airway (PImax), and maximal dynamic inspiratory pressure (PIdyn) and maximal inspiratory flow (V Imax) with no added resistance, as well as the electromyographic activity of the parasternal muscles, were measured during each maneuver. Both maneuvers were initiated from TLC and were performed randomly. In comparison with the S maneuver, the F maneuver yielded values of higher (mean +/- SE) PImax (148 +/- 5 cm H2O versus 135 +/- 7 cm H2O, p < 0.05), PIdyn (33 +/- 2 cm H2O versus 28 +/- 2 cm H2O, p < 0.05), and V Imax (12.3 +/- 0.4 L/s versus 11.4 +/- 0.6 L/s, p < 0.05). In addition, the rate of rise of PImax, the rate of rise of PIdyn, and the integrated peak electromyographic activity of the parasternal muscles were significantly greater with the F than with the S maneuver, suggesting greater inspiratory muscle (IM) activation. The enhanced IM activation may be related to a specific inspiratory-expiratory muscle interaction similar to the agonist-antagonist interactions described for a pair of skeletal muscles.

Respiratory complications after coronary artery bypass surgery with unilateral or bilateral internal mammary artery grafting.

BACKGROUND AND STUDY OBJECTIVE: Use of bilateral internal mammary artery (IMA) grafts during coronary artery revascularization procedures carries the potential for increased incidence of postoperative respiratory complications compared with use of unilateral IMA grafts. The purpose of this study was to compare the incidence of respiratory complications such as hypoxemia, atelectasis, pleural effusion, and diaphragmatic dysfunction in patients who received one or both IMAs as conduit grafts. DESIGN: Prospective, comparative study. SETTING: Surgical ICU at a tertiary teaching hospital. PATIENTS: Seventy-five patients with bilateral and 75 patients with unilateral IMA grafts. MEASUREMENTS: Serial postoperative PaO2/fraction of inspired oxygen measurements, radiographic scores of atelectasis and pleural effusion, duration of mechanical ventilation, length of ICU and hospital stay, and incidence of pneumothorax, pneumonia, and wound infection. RESULTS: There was a higher incidence (51% vs 25%; p=0.002) and severity (0.48+/-0.09 vs 0.15+/-0.05 on the first postoperative day, 0.39+/-0.07 vs 0.27+/-0.07 on the fourth postoperative day, mean+/-SEM; p=0.004) of postoperative right lower lobe atelectasis in the group who received bilateral IMA grafts than in those who received left IMA grafts. This finding probably reflects the effects of additional surgical intervention on the right side of the chest. Incidence and severity of pleural effusion, gas exchange impairment, duration of mechanical ventilation, ICU and hospital stay, and incidence of pneumothorax, pneumonia, and wound infection were not influenced by use of bilateral IMA grafts (p>0.05). CONCLUSION: We conclude that use of bilateral IMA grafts during coronary artery revascularization does not increase the incidence of postoperative respiratory complications compared with unilateral IMA grafting.

Unexpected cardiac arrest after cardiac surgery: incidence, predisposing causes, and outcome of open chest cardiopulmonary resuscitation.

STUDY OBJECTIVES: To assess the incidence of acute mechanical causes precipitating sudden cardiac arrest in cardiac surgery patients during the immediate postoperative period. In addition, we report the success rate of cardiopulmonary resuscitation (CPR) in which open-chest CPR was employed at an early stage of the resuscitation effort. METHODS: Data on all cardiac surgical patients who suffered a sudden cardiac arrest during the first 24 h after surgery were collected prospectively. CPR consisted of conventional closed-chest CPR initially and was followed within 3 to 5 min, if needed, by open-chest CPR. RESULTS: Of 3,982 patients undergoing cardiac surgery over a 30-month period, 29 patients (0.7%) had a sudden cardiac arrest. Of these, 13 patients (45%) were successfully resuscitated with closed-chest CPR, 14 (48%) with open-chest CPR, and 2 (7%) died despite closed- and open-chest CPR. Four CPR survivors died subsequently in the ICU, yielding an overall hospital discharge rate of 79%. Perioperative myocardial infarction was the underlying cause of sudden cardiac arrest in 14 patients (48%), and mechanical impediments to cardiac function (tamponade or graft malfunction) in another 8 (28%) patients; in the remaining 7 patients (24%), no underlying cause was found. The length of ICU stay was 6+/-1 (mean+/-SE) days. None of the patients developed wound infection and all were neurologically intact at hospital discharge. CONCLUSION: Mechanical factors account for a substantial portion (28%) of causes of sudden cardiac arrest occurring in hemodynamically stable patients during the immediate postoperative period. This high incidence, in conjunction with the high survival rate achieved by open CPR, supports an early approach to open-chest CPR in this group of patients.

Effects of severity of long-standing congestive heart failure on pulmonary function.

To investigate the effects of severity of long-standing congestive heart failure (CHF) on pulmonary function, we studied 53 (47 men) consecutive patients, all heart transplant candidates. Their mean (+/- SD) age and ejection fraction were 47 +/- 12 years and 23 +/- 7%, respectively. All patients underwent spirometry, lung volume, diffusion capacity (DLCO), maximum inspiratory (PImax) and expiratory pressure (PEmax) measurement. Maximum cardiopulmonary exercise test on a treadmill was also performed to determine maximum oxygen consumption (VO2max). On the basis of VO2max, the patients were then divided into those with a VO2max > 14 ml min-1 kg-1 (group 1, n = 30) and those with a VO2max < or = 14 ml min-1 kg-1 (group 2, n = 23). In comparison with group 1, group 2 patients had lower FEV1/FVC (70 +/- 8% vs 75 +/- 7%, P = 0.008), lower FEF25-75 (46 +/- 21 vs 70 +/- 26%pred, P < 0.001), lower TLC (76 +/- 15 vs 85 +/- 13%pred, P = 0.02) and lower PImax (68 +/- 20 vs 87 +/- 22 cmH2O, P = 0.003), but comparable DLCO (84 +/- 15 vs 88 +/- 20%pred, P = N.S.), and PEmax (99 +/- 25 vs 96 +/- 22 cmH2O, P = N.S.). In conclusion, our data suggest that respiratory abnormalities, such as restrictive defects, airway obstruction, and inspiratory muscle weakness, are more pronounced in patients with severe CHF than in those with mild-to-moderate disease. Further studies are required to investigate the extent to which these abnormalities contribute to dyspnoea during daily activities in patients with heart failure.

Inspiratory maneuver effects on peak expiratory flow. Role of lung elastic recoil and expiratory pressure.

We investigated the effects of two different inspiratory maneuvers (fast or slow) on the ability of normal subjects to generate peak expiratory flows (PEF) and maximal dynamic expiratory pressures (Pexp) during the performance of a forced vital capacity maneuver. During the fast maneuver (F), the subject inspired rapidly to total lung capacity (TLC) and immediately performed a maximal expiration, whereas in the slow maneuver (S) the subject inspired slowly to TLC, paused for 4-5 s at TLC and then performed a maximal expiration. Ten normal subjects performed a series of such maneuvers. In addition to PEF and Pexp, we measured EMG activity of abdominal (EMGabd) and rib cage muscles, and lung elastic recoil pressure (PesL). Overall, F yielded higher PEF values than S (by approximately 7%); in addition, PesL, Pexp, rate of rise of Pexp (dPexp/dt), and EMGabd were similarly higher with F than with S (p < 0.05 for all). Analysis of individual data showed that the intermaneuver differences in PEF were largely explained by differences in PesL, Pexp or dPexp/dt. Our data suggest that, in comparison with the slow maneuver, the fast maneuver induces a greater change in both the lung elastic recoil and expiratory muscle activation which account for differences in PEF between the two maneuvers. The enhanced expiratory muscle activation with the fast maneuver suggests a specific inspiratory-expiratory muscle interaction analogous to agonist-antagonist interactions described for skeletal muscles.