Omar Al-Rawas

To explore the consequences of translating the International Study of Asthma and Allergies in Childhood (ISAAC) English core questionnaires on asthma, rhinitis and eczema symptoms into other languages. ISAAC Phase III developed 49 language translations for adolescents and 42 for children following standardised guidelines, which included back-translating the questionnaires into English to check their accuracy and meaning. Language deviations were categorised and analysed with regard to influences on the reported symptom prevalence. Category 1 deviations for one or more questions were found in seven translations (14%) for adolescents and in three translations (7%) for children. Data for these questions were excluded from the worldwide analyses. Category 2 deviations were identified in the publications, and Category 3 deviations were ignored. Translations of questionnaires should follow a consistent protocol in global epidemiological research. Cultural norms need to be considered when ...

Centres in Phases I and III of the International Study of Asthma and Allergies in Childhood (ISAAC) programme used the method of consent (passive or active) required by local ethics committees. Retrospectively, relationships between achieved response rates and method of consent for 13-14 and 6-7-year-olds (adolescents and children, respectively), were examined between phases and between English and non-English language centres. Information was obtained for 113 of 115 centres for adolescents and 72/72 centres for children. Both age groups: most centres using passive consent achieved high response rates (>80% adolescents and >70% children). English language centres using active consent showed a larger decrease in response rate. Adolescents: seven centres changed from passive consent in Phase I to active consent in Phase III (median decrease of 13%), with five centres showing lower response rates (as low as 34%). Children: no centre changed consent method between phases. Centres ...

Associations between exposure to cats and dogs and respiratory and allergic outcomes in children have been reported in affluent countries, but little is known about such associations in less-affluent countries. The International Study of Asthma and Allergies in Childhood, phase 3 was carried out in children aged 6-7 years and adolescents aged 13-14 years across the world. Questions about cats and dogs in the home were included in an additional questionnaire. Using logistic regression, we investigated the association between such exposures and symptoms of asthma, rhinoconjunctivitis, and eczema. Adjustments were made for sex, region of the world, language, gross national income per capita, and 10 other covariates. Among children (6-7 years of age), cat exposure in the first year of life was associated with current symptoms of asthma, wheeze, rhinoconjunctivitis, and eczema, especially in less-affluent countries. Among adolescents (13-14 years of age), we found a positive association between exposure to cats or dogs and symptom prevalence in more-affluent and less-affluent countries. The global multivariate odds ratios for children with complete covariate data were 1.17 (95% confidence interval = 1.08-1.29) for current symptoms of asthma, 1.13 (1.05-1.23) for rhinoconjunctivitis, and 1.38 (1.26-1.52) for eczema. Smaller odds ratios were found for exposure to only dogs. Exposure to only cats was associated with eczema. Early-life exposure to cats is a risk factor for symptoms of asthma, rhinoconjunctivitis, and eczema in 6- to 7-year-old children, especially in less-affluent countries. Current exposure to cats and dogs combined, and only to dogs, is a risk factor for symptom reporting by 13- to 14-year-old adolescents worldwide.

To analyse trends of tuberculosis (TB) in Oman (1981-2005) in relation to the socio-economic development of the country. Data were used from the National Tuberculosis Control Programme (NTP). Information on TB cases' age, sex and type were obtained from the national book (1981-1991) and the computer database (1992-2005). TB notification rates among Omani nationals declined by more than 85% from 1981 to 1995. During the period 1981-1993, the TB notification rate declined by around 15% per year, compared to only 3.6% per year in subsequent years. Males and the age group > or = 50 years have higher rates than females and younger age groups, respectively. Non-nationals contributed 21% of all TB cases notified and 40% of all smear-positive cases. Of cases among nationals notified between 2004 and 2005, 95% had a family income lower than the national average. Although TB notification in Oman has declined by more than 85% over the last 25 years, the decline has slowed down over the last 10 years, requiring a detailed analysis of existing TB control measures and implementation of additional measures for TB elimination.

To determine the range of serum IgE in healthy subjects and in asthmatic patients in Oman and to assess the degree of atopy in the asthmatic patients. Serum IgE and in vivo (the skin prick test) and in vitro (the ImmunoCAP test) allergen-specific IgE levels were measured in 44 patients with asthma. Control groups were 19 healthy subjects and 27 asymptomatic allergic subjects. The normal range for serum IgE in the Omani population was established at ≥ 101 IU/ml. The geometric mean (and 95% confidence interval) for asthmatic patients was 468 IU/ml (323-676). Positive results for allergen-specific IgE, defined as responses to ≥ 1 allergen mix in the ImmunoCAP and to ≥ 3 allergens in the skin prick test, occurred in 26/35 (74%) and in 34/44(77%) asthmatic patients respectively. Six out of 38 patients with serum IgE ≥ 101 IU/ml and 2/6 with levels <101 IU/ml gave negative and positive results respectively in the skin prick test. Overall, the degree of reactivity in the skin prick test correlated with the level of total serum IgE (r= 0.54, p<0.001). A similar correlation could not be established with ImmunoCAP reactivity, but sIgE levels ≥ 101 IU/ml were supported by a high frequency of positive ImmunoCAP responses for the majority of allergen mixes. Total serum IgE levels should be routinely monitored in asthmatic subjects as this may give an indication of atopy where skin prick testing is not indicated. Since in a minority of patients serum IgE levels and skin prick results do not predict in the same direction, all laboratory data should be interpreted in context of clinical history.

This study aims to determine what objects lying in the hospital environment or brought in from outside contribute to the introduction of bacteria associated with nosocomial infections. One hundred swab specimens collected from children's toys, sinks, door handles, telephone handsets and flowers brought into the hospital were plated on different culture media. Colonial growth on the media was purified and identified subsequently using standard bacteriological methods. Of the 100 samples cultured, 61 (61%) grew a range of bacteria including Pseudomonas aeruginosa (n=14, 23.0%), Acinetobacter spp. (n=13, 21.3%), Serratia spp. (n=9, 14.7%), Staphylococcus epidermidis (n=9, 14.7%), Stenotrophomonas maltophilia (n=4, 6.6%), Staphylococcus aureus (n=4, 6.6%), Enterobacter cloacae (n=3, 4.9%), Pantoea sp. (n=2, 3.3%), Chryseobacterium sp. (n=2, 3.3%) and Klebsiella pneumoniae (n=1, 1.6%). Although all the Serratia, Enterobacter, Klebsiella and Pantoea species isolates showed varying degrees of resistance to gentamicin, ceftriaxone, cefuroxime and cefotaxime, all were resistant to ampicillin. Chryseobacterium and Stenotrophomonas species isolates were resistant to amikacin, imipenem, gentamicin and ceftazidime, to which only three isolates of Pseudomonas species were resistant. All the staphylococcal isolates were susceptible to methicillin. Although there has been no major outbreak of a nosocomial infection in the hospital, it is strongly recommended that effective control measures (e.g., sampling the hospital water supply, disinfecting children's toys, use of appropriate hand washing and checking some of the disinfectants for presence of bacteria) are needed. These measures are necessary to ensure that the antibiotic-resistant strains identified in this study are not allowed to spread in the hospital.

SETTINGS: National Tuberculosis Reference Laboratory, Central Public Health Laboratory, Ministry of Health, Oman.OBJECTIVE: To use spoligotyping to explore the genetic population structure and clustering of Mycobacterium tuberculosis isolates among nationals and immigrants in Oman.METHODS: Using spoligotyping, we characterised all available isolates from 2007, and randomly selected isolates from 2005 and 2006. A total of 312 clinical isolates from the same number of patients diagnosed with tuberculosis (TB) in 2005-2007 were included in the study.RESULTS: Of 312 isolates, 69% were in clusters ranging from 2 to 38 isolates. The proportion of clustering was 58% among 2005-2006 samples and 67% among 2007 samples, with higher clustering among Omanis than among immigrants. The study showed that M. tuberculosis Indian family lineages, CAS1_Delhi, CAS and EAI5 were the predominant strains. Around 50% of the immigrants shared strains with Omanis. Twelve of the 19 INH-monoresistant strains a...

To determine the range of serum IgE in healthy subjects and in asthmatic patients in Oman and to assess the degree of atopy in the asthmatic patients. Serum IgE and in vivo (the skin prick test) and in vitro (the ImmunoCAP test) allergen-specific IgE levels were measured in 44 patients with asthma. Control groups were 19 healthy subjects and 27 asymptomatic allergic subjects. The normal range for serum IgE in the Omani population was established at ≥ 101 IU/ml. The geometric mean (and 95% confidence interval) for asthmatic patients was 468 IU/ml (323-676). Positive results for allergen-specific IgE, defined as responses to ≥ 1 allergen mix in the ImmunoCAP and to ≥ 3 allergens in the skin prick test, occurred in 26/35 (74%) and in 34/44(77%) asthmatic patients respectively. Six out of 38 patients with serum IgE ≥ 101 IU/ml and 2/6 with levels <101 IU/ml gave negative and positive results respectively in the skin prick test. Overall, the degree of reactivity in the skin prick test...

The management of asthma by specialists is likely to become more evidence-based. This study analysed the characteristics of patients reporting to a specialist clinic including demographics, dispensed medications and the level of asthma control. All consecutive stable asthmatics seen in the adult pulmonary clinics of Sultan Qaboos University Hospital, Oman, between December 2005 and November 2006 were prospectively evaluated using a structured assessment protocol. Of the 207 patients, (mean age 40.64 ±14.8), 72% were females. The majority, 83.1%, had moderate persistent asthma. A positive history of allergic rhinitis, eczema and a family history of asthma were obtained in 58.0%, 11.1%, and 50.7% of patients respectively. Total serum immunoglobulin E (IgE) was elevated in 66.7%. Skin testing was positive for more than 2 antigens in 52.3%, with the house dust antigen being reactive in 49%. Inhaled steroids, long-acting beta agonists (LABA), antihistamines and leukotriene receptor antag...

Studies continue to show poor physician compliance with asthma management guidelines in clinical practice. However, standardized protocols specifically designed to be practical and user-friendly improve patient outcomes. To determine the degree of physicians' compliance with the documentation of an asthma management protocol in a university hospital. A simple asthma management protocol was designed and applied in our pulmonary clinic and primary care clinic for asthma. The protocol was based on the 1998 Manual for the Management of Asthma, from the Oman Ministry of Health, which follows internationally recognized guidelines. The protocol consisted of 4 sections: clinical history, peak expiratory flow (PEF) data, medication section, and simplified asthma management guidelines. All 30 physicians scheduled to conduct asthma clinics in the pulmonary clinic (14 physicians) and the primary care clinic (16 physicians) agreed to use the protocol. A total of 282 protocol forms were colle...

The focus in medical education has shifted from teaching to learning, largely because of a shift from didactic teaching to problem-based learning (PBL). The review article published in the recent edition of Saudi Journal of Medicine was relevant and highlights various advantages of ...

A 50-year-old Arab woman presented with a 3-month history of fever, weight loss, and tiredness. She noticed mild shortness of breath on exertion a month before presentation. She looked fairly healthy, a few cervical lymph nodes were palpable, and the chest examination showed features of a right-sided pleu- ral effusion. A chest radiograph showed a right pleural effu- sion and

Snoring and obstructive sleep apnea (OSA) are common disorders. Snoring associated with excessive daytime sleepiness is the most prevalent symptoms of OSA. Heart rate variability (HRV) is altered in patients with OSA and the degree of alteration may be linked to the severity of OSA. Alterations in HRV in 24 hour tachograms have recently been used in screening OSA patients. Autonomic components causing HRV can be reliably studied using spectral analysis techniques involving fast Fourier transformation (FFT). Twenty-three subjects, 13 with severe OSA and 10 controls matched for age and body mass index, were selected from patients who had undergone polysomnography (PSG) for snoring at Sultan Qaboos University Hospital, Oman. A 24- hour electrocardiogram (ECG) Holter recording was done at home, starting at 10am. Spectral analysis of ECG from sleep Holter and PSG recordings was analysed using fast Fourier transformation (FFT). The ECG RR intervals of snorers with OSA were significantly s...

Obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is a disorder characterised by repetitive upper airway collapse during sleep in association with daytime sleepiness. It has an estimated prevalence of 2% and 4% among middle-aged women and men respectively. The aim of the study was to look at the association of body mass index (BMI), age and gender and prevalence of OSAHS in the Omani population. Polysomnography reports and hospital medical records of all patients who took part in the Sleep Study at the Sleep Laboratory of the Clinical Physiology Department, Sultan Qaboos University Hospital, between January 1995 and December 2006, were retrospectively reviewed. Data from both sources was gathered and analysed. A total of 1,042 sleep studies were conducted with 608 valid studies for analysis. The study showed that the apnoea/hypopnoea index (AHI) >15 was more prevalent in men compared to women (47.9% versus 33.5%, P = 0.001). There was significant correlation of AHI with BMI (P ...

To determine the mechanism of impairment of pulmonary transfer factor for carbon monoxide (TL(CO)) in heart transplant candidates, as this is the most common lung function abnormality. Regional cardiopulmonary transplant centre. TL(CO) and its components (the diffusing capacity of the alveolar-capillary membrane (D(M)) and the pulmonary capillary blood volume (V(C))) were measured using the Roughton and Forster method and the single breath technique in 38 patients with severe chronic heart failure awaiting heart transplantation (mean age 51 years, range 19 to 61; mean left ventricular ejection fraction 12.8%). Results were compared with data from 26 normal subjects (mean age 47 years, range 27 to 62). Mean per cent predicted TL(CO), D(M), and V(C) were significantly reduced in patients (69.9%, 81.4%, and 80.2% of predicted, respectively) compared with controls (97.7%, 100.1%, and 102.3% of predicted, respectively, p < 0.001). The relative contribution of the two components of TL(...

Heart transplantation is an established treatment for end stage heart failure. In addition to increased life expectancy, heart transplant recipients report a remarkable improvement in symptoms and functional capacity. Exercise performance following heart transplantation, however, remains impaired even in the absence of exertional symptoms. We have assessed the response to exercise in 47 patients with cardiac failure prior to and then at yearly intervals to five years post transplantation. All patients performed incremental symptom limited exercise tests during which minute ventilation (V'E), oxygen consumption (V'O2) and carbon dioxide production (V'CO2) and heart rate (HR) were measured. Ventilatory response (V'E/V'CO2), anaerobic threshold (V'O2 AT %predicted) and heart rate response (HR/VO2) were calculated. The dead space to tidal volume ratio (VD/VT) and alveolar-arterial oxygen gradient (A-aO2) were computed from transcutaneous monitoring. Despite substantial improvement in subjective functional capacity, heart transplant recipients continue to have limited exercise performance [Maximal V'O2% predicted pre-transplant 41.3 (2.2); 1 year 48.6 (1.7), p <0.001: V'O2 AT% 31.5 (1.1); 1 year 35.6 (1.0); respectively p<0.05]. The maximal oxygen uptake continued to improve at two years post-transplant but, thereafter, there was no further significant change at up to 5 years post transplant [50.9 (1.5)]. At one year post-transplantation peak HR [65.2 (0.9) vs 79.1(1.4)] and the HR/VO2 response [24.0(1.8) vs 79.6(4.2)] were significantly reduced compared to pre-transplant values. The heart rate response remained lower compared to predicted at 5 years post-transplant although there was a significant increase compared to one year post-transplant (32.9 vs 24.0mls/bt). There was a weak but significant relationship between maximal VO2 and peak HR (0.39, p<0.05) and HR/VO2 (r= 0.37, p<0.05) at one year post-transplant. Prior to transplantation the ventilatory response to exercise was elevated [V'E/V'CO2 45.6 (2.5)] and decreased significantly following transplantation [1 yr 34.1 (1.3), respectively p<0.001]. In addition, despite significant improvement in VD/VT after transplantation, it remained higher than normal [Pre VD/VT at maximum exercise 0.35 (0.02); 1 yr 0.31 (0.02); p<0.05]. There was a further fall in the VE/VCO2 and VD/VT at two years post-transplantation with no further change at up to 5 years post transplantation [VE/VCO2 32.0 (1.0); VD/VT 0.29 (0.01)]. Although cardiac output is markedly improved after transplantation, due to chronotropic incompetence associated with denervation, its response remains subnormal and this may explain the residual abnormalities of ventilatory and gas exchange responses to exercise following transplantation.

In contrast to the standard single-breath transfer factor for carbon monoxide (TLCO), there are no specific guidelines or recommendations for the measurement of its components, the pulmonary capillary blood volume (VC) and membrane component (DM), by the Roughton and Forster method. Ten randomly selected heart transplant patients (three life-long non-smokers, seven ex-smokers > 1 yr, age range 24-55 years) were assessed on two occasions using either the standard or high-oxygen mixture as the first inspired gas in random order. Ten normal subjects (all non-smokers, age range 23-54 years) were assessed on two occasions using either a long protocol (30 min waiting time between repeat measurements in an individual set) or a short protocol (5 min waiting time). Two technically acceptable results of TLCO were used to derive a mean value for DM and VC for each set of measurements (Transflow, P. K. Morgan, Kent, U.K.). The different sequences of gas mixtures produced no significant differences between the values obtained in ten heart transplant patients for mean TLCO (mmol min-1 kPa-1) (standard first 5.13 +/- 1.15, high-oxygen first 5.14 +/- 1.12; limits of agreement -0.57 to 0.59 for DM or for VC. The long or short protocol produced no significant differences between the means of TLCO (mmol min-1 kPa-1) (long 8.0 +/- 1.9, short 8.0 +/- 1.9; limits of agreement -0.5 to 0.5), DM or VC. This allows the development of a standard test protocol of short duration (about 40 min) making it practical for clinical use without compromising the precision or reproducibility of the results obtained.

International guidelines recommend the use of population-specific reference values to eliminate the well-recognized influence of ethnic variation on lung function. This study was designed to derive spirometric prediction equations for healthy Omani adults. Forced vital capacity (FVC), forced expiratory volume in one second (FEV(1)), peak expiratory flow rate (PEFR), and forced expiratory flow at 25% to 75% of FVC (FEF(25-75%)) were measured in 419 "healthy" nonsmoking Omani adults (256 men, 163 women), aged 18-65 years. Multiple linear regression analysis was performed for each spirometric parameter against age, height, and weight for men and women separately, and prediction equations for all the above parameters were derived and compared with values derived using equations published from other populations. All measured spirometric parameters increased with height and decreased with age, and they were all significantly higher in men. In contrast, FEV(1)/FVC% values decreased with height and increased with age and were higher in women. The predicted normal values of FVC and FEV(1) for our subjects using the derived equations were lower by 7-17% compared with respective Caucasian values, with smaller difference in the predicted values of PEFR, FEV(1)/FVC%, and FEF(25-75%). This report presents previously unavailable spirometric reference equations for the Omani adults. Our findings highlight the need to use reference values based on updated data derived from relevant populations.

The available assessment tools to determine asthma control do not include components assessing factors that may directly affect control. Our aim was to evaluate the relationship between patient compliance, inhaler technique and the level of asthma control. Scores from the Asthma Control Test, individual inhaler device checklists and a novel questionnaire on the patient's medication regimen were used to measure control, inhaler technique and compliance, respectively, in patients with asthma attending Sultan Qaboos University Hospital, Muscat, Oman during a 3-month period. All of the 218 patients were receiving inhaled steroids, either in combination with long-acting beta agonists (86.2%) or alone. Asthma control was good in 92 (42.2%) patients; with 38 males (50%) and 54 females (38%), respectively (p = 0.059). Compliance and inhaler technique were poor in 40.8% (89) and 18.3% (40) of the patients. 60% (36) of the patients with good and 59.4% (41) with partial compliance had good control while 83.1% (74) with poor compliance had poor control (p < 0.001). Of the 92 patients with good control, 86 (93.5%) exhibited good inhaler techniques. In contrast, 85% (34) of the patients with poor inhaler techniques demonstrated poor control (odds ratio [OR] = 5.3; 95% confidence interval [CI]: 2.05-14.8; p < 0.001). A total of 93.3% (56) with good and 89.9% (62) with partial compliance demonstrated good inhaler techniques (p < 0.001). In patients with good control, 35 (38%) exhibited both good inhaler techniques and compliance and 38 (41.3%) had a good technique and partial compliance. Patients with good inhaler techniques and compliance have better control of their asthma. Asthma control will remain suboptimal unless the reasons for this lack of control are identified, assessed and eliminated. We recommend that inhaler technique assessment and measurements of patient compliance with their prescribed treatments should be considered for inclusion in the current assessment tools.

The high prevalence of lactase persistence (LP) among the people of Saudi Arabia is associated with the -13915(*)G variant allele upstream of the lactase gene (LCT). We, therefore, examined the frequency of the commonly known LP associated SNPs among randomly collected samples from Omani and Yemeni adult populations and obtained further data on the distribution of the two most common LP-associated variants, -13910(*)T and -13915T(*)G, in the Arabian Peninsula. The DNA fragment containing all the reported LP- associated SNPs was amplified and genotyped. The frequency of the -13915(*)G allele was highest among Dhofari Arabs of southern Oman (0.72) followed by Yemeni Arabs (0.54) and Arabs of northern Oman (0.14). It was not detected in Omanis of Asian origin. The frequency of the -13910(*)T allele was extremely low in Arabs of northern and southern Oman (0.00-0.01) and Yemenis (0.002). However, it had a frequency of 0.160 among Omanis of Asian origin. Results show that the highest frequency of the LCT -13915(*)G variant allele appears to be in the south of the Arabian Peninsula with clinal decrease within the Peninsula and further out in surrounding countries.

Although the decline in the pulmonary transfer factor (TL(CO)) following heart transplantation is well documented, the causes and mechanisms of this decline remain unknown. The aim of this study was to determine the relative contribution of each of TL(CO) components (the diffusing capacity of the alveolar-capillary membrane (D(M)), the pulmonary capillary blood volume (V(C)) and haemoglobin concentration) to TL(CO) reduction in heart transplant recipients. TL(CO) and its components were measured in 75 heart transplant recipients (mean age 48 years, range 19-61) between 6 weeks and 36 months after transplantation using the Roughton and Forster method and the single-breath technique. Results were compared with data from 38 heart transplant candidates (mean age 51 years, range 34-61) and 26 normal subjects (mean age 47 years, range 27-62). The mean percentage predicted TL(CO) was reduced in recipients compared to candidates (56.9 and 69.9%, respectively, P<0. 001) and both were lower than normal controls (97.7%, P<0.001). The mean percent predicted V(C) was also reduced in recipients compared to candidates (52.8% vs. 80.2 (4.2)%, P<0.001) which was also lower than normal subjects (102%, P<0.001). D(M) was equally reduced in recipients and candidates (77.7 and 81.4%, respectively, P=0.48) compared to normal subjects (100.0%, P<0.001). Correction for haemoglobin concentration increased TL(CO) in recipients to 63.5% (P<0.001), but it remained lower than haemoglobin-corrected TL(CO) in candidates (71.1%, P<0.001). In recipients, the intra-capillary resistance (1/thetaV(C)) formed 60% of the total resistance to CO transfer (1/TL(CO)) compared to 50% in candidates and normal subjects. TL(CO) decline following heart transplantation is due to an increase in the intra-capillary resistance, and this appears to be due to a combination of anaemia and reduced pulmonary capillary blood volume, with the diffusing capacity of the alveolar-capillary membrane remaining unchanged.

Although 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. Descriptive cohort study. A regional cardiopulmonary transplant center. Twenty-six heart transplant recipients who were studied before and after transplantation compared with 26 healthy volunteers. Spirometry 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. Before 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. DLCO reduction after heart transplantation appears to represent persistent gas exchange impairment and contributes to exercise limitation in heart transplant recipients.