RESUMO
Lung transplantation (LT) is a recognized procedure for selected patients with end-stage respiratory failure. We performed 123 LT, including 32 single lung, 84 double lung, and 7 heart-lung transplantations in 48 patients with chronic obstructive pulmonary disease (COPD), 13 patients with pulmonary hypertension (PH), 33 with cystic fibrosis (CF), and 29 with interstitial lung disease (ILD) between July 1990 and January 2008. Survival was compared for periods before and after December 2001. The mean age of patients was 44.4 years (range 16-66.5 years); 84 (69%) were men. Before LT, 1 second forced expiratory volume was 28.7% +/- 18.1% and PaCO(2) = 6.3 kPa. Fifty-five patients were on noninvasive ventilation. Cold ischemia time was 320 +/- 91 minutes. Cardiopulmonary bypass (CPB) was used in 77 patients (64%). There were 18 early surgical reinterventions, 8 extracorporeal membrane oxygenations, and 38 bronchial stent insertions among 206 at-risk bronchial sutures. Crude survivals were 69%, 58%, 41%, and 18% at 1, 2, 5, and 10 years, respectively. Comparing before (n = 70 with 15 CF) vs after December 2001 (n = 53 with 17 CF), survivals were 63% vs 78%, 51% vs 71%, and 33% vs 60% at 1, 2, and 5 years, respectively (P = .01) and for CF patients, 52% vs 100%, 52% vs 94%, and 25% vs 94% at 1, 2, and 5 years, respectively (P = .005). There was significant improvement in survival before and after 2001 in 123 LT and particularly among CF patients. Improvement in survival after LT may be related to the sum of numerous changes in our practice since December 2001, including the use of pulmonary rehabilitation pre-LT, extracellular pneumoplegia, statins, macrolides for chronic rejection, monitoring of Epstein-Barr blood load, changes in maintenance immunosuppressants, as well as position movement up the coordinator nurse and learning curve.
Assuntos
Sobrevivência de Enxerto/fisiologia , Transplante de Pulmão/fisiologia , Fibrose Cística/cirurgia , Feminino , Transplante de Coração-Pulmão/mortalidade , Transplante de Coração-Pulmão/fisiologia , Humanos , Hipertensão Pulmonar/cirurgia , Pneumopatias/cirurgia , Transplante de Pulmão/mortalidade , Masculino , Doença Pulmonar Obstrutiva Crônica/cirurgia , Estudos Retrospectivos , Análise de Sobrevida , SobreviventesRESUMO
OBJECTIVE: Few studies have shown that aged packed red blood cells (RBC) transfusion negatively influenced the outcome of ICU patients, probably related to storage lesions which could be decreased by leukodepletion of RBC. The purpose of this study was to evaluate the impact of aged leukodepleted-RBC pack, on the outcome of ICU patients. DESIGN: Retrospective, observational, cohort study in a Medical Intensive Care Unit. PATIENTS: Consecutive patients admitted during the years 2005 and 2006, and requiring a transfusion. We recorded patient's demographic data, number of RBC unit and age of each RBC, length of ICU, mortality during ICU stay. RESULTS: Five hundred and thirty-four patients were included with global mortality was 26.6%, length of stay in ICU six days (3-14) and SAPS II 48 (35-62). RBC equaling to 5.9 were transfused per patients (22.7%<14 days and 57.3%<21 days). The number of RBC was significantly higher in the dead patients group, but the rate of RBC stored less than 21 days was not different (54% versus 60%; p=0.21). In a multivariate logistic model, independent predictors of ICU death were SAPS II (OR=1.02 per point, p<0.001), number of RBC (OR=1.08 per RBC, p<0.001), length of stay in ICU (p<0.001). Similar results were obtained while introducing the age of RBC as time dependent covariates in a multivariate Cox's model. CONCLUSIONS: RBC transfused in our ICU are old. The ICU outcome is independently associated with the number of leucodepleted RBC transfused, but not with their age.
Assuntos
Envelhecimento Eritrocítico/fisiologia , Transfusão de Eritrócitos/métodos , Eritrócitos/fisiologia , Idoso , Comorbidade , Transfusão de Eritrócitos/normas , Eritrócitos/citologia , Feminino , Humanos , Unidades de Terapia Intensiva , Tempo de Internação , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Sepse/mortalidade , Sepse/terapia , Choque Hemorrágico/mortalidade , Choque Hemorrágico/terapia , Análise de Sobrevida , SobreviventesRESUMO
Blood measurements of BNP and NT-proBNP, its catabolite, improve diagnosis for patients admitted to emergency departments with dyspnoea. In this paper, we have compared the BNP to the NT-proBNP for 119 dyspnoeic patients using at random clear clinical status. Among the test group of 119 patients, 57 showed coherent biological results for the 2 markers. These results confirm the final clinical diagnosis. Nine patients with congestive heart failure had abnormally low BNP and NT-proBNP rates. Six of these patients experienced long delays (longer than 48 hours and less than 72 hours) between their admission in emergency and the biological measurement of the natriuretic biomarkers. Three of the other patients could be not only flash OAP cases with a fast growth and a fast normalisation of BNP but also could have existing genetical factors. These genetical factors leading to high variability in BNP synthesis are not related to physiological or cardiac factors. 43 patients showed a mismatch between BNP and NT-proBNP. BNP appeared to be unstable in vitro. The lack of stability in whole blood or plasma samples is increased by sampling in a glass EDTA collection tube and too long delays in transferring the samples from the emergency area and the laboratory in a big hospital. Ten patients showed a mismatch with abnormally high NT-proBNP or false positive results. Among these 10 patients, 5 had renal dysfunction with a high level of creatinine concentration. It is clear that all Diagnostics Manufacturers should now propose different cut-off for natriuretic peptides tests according to the degree of patients' renal impairment.
Assuntos
Dispneia/diagnóstico , Natriuréticos/sangue , Peptídeo Natriurético Encefálico/sangue , Fragmentos de Peptídeos/sangue , Precursores de Proteínas/sangue , Idoso de 80 Anos ou mais , Biomarcadores/sangue , Creatinina/sangue , Diagnóstico Diferencial , Serviço Hospitalar de Emergência , Reações Falso-Negativas , Reações Falso-Positivas , Feminino , Insuficiência Cardíaca/diagnóstico , Humanos , Laboratórios Hospitalares , Pneumopatias/diagnóstico , Masculino , Admissão do Paciente , Fatores de TempoRESUMO
A 48 year old man was admitted to the intensive care unit with septicaemic shock associated with febrile jaundice and anuric renal failure. Within hours, he developed cardiogenic shock with multi-organ failure due to an acute myocarditis refractory to catecholamines and requiring intra-aortic balloon pumping. The diagnosis was an ictero-haemorrhagic leptospirosis, the outcome of which was finally favourable. Myocarditis is an underestimated complication of leptospirosis because it is often symptomless. The main signs are arrhythmias, conduction defects and ST-T wave abnormalities which have little clinical expression. The disease may progress and is sometimes fatal. Leptospirosis myocarditis should therefore be carefully considered because of its potential severity and its reversibility with appropriate antibiotic therapy and also the necessity of initial management in a specific infrastructure.
Assuntos
Miocardite/complicações , Miocardite/microbiologia , Choque Cardiogênico/etiologia , Doença de Weil/diagnóstico , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
BACKGROUND & AIMS: Peripherally inserted central venous catheters (PICC) have become increasingly popular for medium to long-term parenteral nutrition (PN) but there is limited data on the complication rates in this sub-group. We aimed to compare the rates of complications associated with tunneled catheters (Broviac) and PICC in home PN (HPN) patients. METHODS: All adult patients in an HPN program with a new Broviac or new PICC between 2009 and 2011 were included in this prospective observational study. Complication rates were compared by using Poisson regression and Kaplan Meier survival curves were used to compare the first complications that occurred. RESULTS: 204 catheters (133 Broviac and 71 PICC) were inserted in 196 adult patients. Mean follow-up from catheter insertions to their removal was 276 ± 219 days for Broviac (n = 86) vs. 74 ± 140.70 days for PICC (n = 56); p < 0.001. Complications were similar between Broviac and PICC (91/133 vs. 26/71). Catheter infection rate was lower in PICC (1.87 vs. 1.05 per 1000 catheter-days; p = 0.01). Catheter obstruction rates were similar for both catheters. Only PICC experienced venous thrombosis (0.4/1000). The proportion of catheters removed was lower in the Broviac group than in the PICC group (62.4% vs. 78.8%; p = 0.01) but those removed for complications were not different (28.6.7%vs. 25.3%; p = 0.64). CONCLUSIONS: In HPN patients, overall complications were similar in both the PICC and the Broviac groups. However, the Broviac catheter could be associated with an increase in catheter infection.
Assuntos
Cateterismo Venoso Central/efeitos adversos , Cateterismo Periférico/efeitos adversos , Catéteres/efeitos adversos , Nutrição Parenteral no Domicílio/instrumentação , Idoso , Obstrução do Cateter/estatística & dados numéricos , Infecções Relacionadas a Cateter/epidemiologia , Infecções Relacionadas a Cateter/microbiologia , Cateteres Venosos Centrais , Humanos , Pessoa de Meia-Idade , Estudos Prospectivos , Trombose Venosa/epidemiologiaRESUMO
Patients suffering from acute respiratory failure are considered poor candidates for lung transplantation (LT). We report a successful double lung transplantation performed in a patient with adult respiratory distress syndrome (ARDS). The 32-year-old woman received recombinant interleukin 2 (rIL-2) three months after an autologous bone marrow transplant for acute myelogenic leukemia as consolidation treatment. After four days of treatment with rIL-2, she developed ARDS which worsened over a three-week period, despite treatment. Lung transplantation was carried out as ultimate treatment. The postoperative course was uneventful. The patient is alive and in a good condition 11 months after LT. This case demonstrates the feasibility of LT in selected patients with ARDS. However, this case is exceptional since lung grafts should be utilized preferably for evaluated and accepted patients in transplant programs.
Assuntos
Interleucina-2/efeitos adversos , Transplante de Pulmão , Síndrome do Desconforto Respiratório/cirurgia , Adulto , Feminino , Humanos , Interleucina-2/uso terapêutico , Radiografia , Proteínas Recombinantes/efeitos adversos , Síndrome do Desconforto Respiratório/diagnóstico por imagem , Síndrome do Desconforto Respiratório/etiologiaRESUMO
Alloreactivity is caused by T cell recognition of foreign histocompatibility antigens according to two models: (i) indirect recognition, in which processed allogeneic antigens are presented by self-major histocompatibility complexes like any other foreign antigen, and (ii) direct recognition, where the foreign MHC itself is recognized breaking the T cell recognition rule of self-restriction. This paper uses these two cases of alloantigen presentation as illustrative examples to investigate (i) the capacity of Epstein-Barr virus-transformed B cells (EBV-B cells) to process alloantigens, and (ii) in vitro assays with EBV-B cell lysate as a source of alloantigen, in order to characterize alloreactive T cell populations. A microculture system was established using donor EBV-B cell lysate as a source of the allogeneic antigen and donor or recipient EBV-B cells as antigen presenting cells to investigate whether alloantigen is recognized by effector T cells from the recipient. T lymphocytes produced after expansion in the presence of interleukin-2 from four samples of liver biopsies (three patients) and four samples of bronchoalveolar lavages (four patients) were used as effector cells. Upon human leucocyte antigen class II typing, these expressed the patient phenotype. When the T lymphocytes were from liver grafts, the recognition involved donor antigens presented by donor EBV-B cells (direct recognition). On the other hand, when the T lymphocytes were cultured from lung grafts, they mainly recognized antigens of donor EBV-B cell lysates in a self-restricted context (indirect recognition). These data suggest that EBV-B cells can provide allogeneic determinants recognized by T cells in donor or self-contexts, i.e. through either direct or indirect recognition.
Assuntos
Linfócitos B/imunologia , Herpesvirus Humano 4 , Isoantígenos/imunologia , Transplante de Fígado/imunologia , Transplante de Pulmão/imunologia , Linfócitos T/imunologia , Adulto , Lavagem Broncoalveolar , Linhagem Celular Transformada , Transformação Celular Viral , Células Cultivadas , Feminino , Humanos , Interleucina-2/farmacologia , Fígado/citologia , Fígado/imunologia , Masculino , Pessoa de Meia-Idade , Proteínas Recombinantes/farmacologia , Linfócitos T/citologia , Doadores de Tecidos , Transplante HomólogoRESUMO
A 58-year-old man underwent sequential bilateral lung transplantation. On the donor heart-lung block, it was discovered that the right apical segment was supplied by a tracheal bronchus. After the separate implantation of both lungs, a right apical segmentectomy was performed and the postoperative course was uneventful. The management of this problem is discussed.
Assuntos
Brônquios/anormalidades , Transplante de Pulmão/métodos , Traqueia/anormalidades , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
BACKGROUND: Total parenteral nutrition (TPN) may offer significant clinical benefit in malnourished patients with acquired immunodeficiency syndrome (AIDS). However, the immunologic effect of parenteral lipids remains unknown in these severely immunodepressed patients. METHODS: We undertook a prospective randomized double-blind multicenter study comparing the effects of two i.v. lipid emulsions used during TPN: long-chain triglycerides (LCT) or balanced emulsion of long-and medium-chain triglycerides (LCT/MCT). Thirty-three AIDS patients requiring TPN for wasting and reduced oral intake were allocated randomly to receive a ternary TPN mixture consisting of 1.5 g/kg/d proteins, 18 kcal/kg/d lipids, and 12 Kcal/kg/d carbohydrates for 6 days. The following tests were performed at days 0 and 7: immunoglobulins, complement fractions, lymphocyte subpopulations count, and lymphocyte proliferation with mitogens. RESULTS: Patients were all severely malnourished (weight loss: -14.0 +/- 1.3 kg). No clinical or biological differences were observed between the groups at baseline. At day 7, both groups reported a significant increase in weight. Patients in the LCT group exhibited a significant decrease in phytohemagglutinin A response (p = .04) compared with baseline. Patients in the LCT/MCT group exhibited a lower level of IgM (p = .03) and significant increase in C3 fraction (p = .03) compared with baseline. They also showed a tendency to have a higher CD4/CD8 lymphocyte ratio (p = .07), whereas other immunological parameters remained unchanged CONCLUSIONS: Parenteral ternary mixture containing LCT or LCT/MCT are clinically well tolerated in AIDS patients over 6 days. With 2 g/kg/d of lipids, LCT seems to induce significant abnormalities in lymphocyte function. Such abnormalities are not observed with LCT/MCT.
Assuntos
Síndrome da Imunodeficiência Adquirida/imunologia , Síndrome da Imunodeficiência Adquirida/terapia , Subpopulações de Linfócitos/efeitos dos fármacos , Distúrbios Nutricionais/terapia , Nutrição Parenteral Total/métodos , Triglicerídeos/farmacologia , Síndrome da Imunodeficiência Adquirida/complicações , Estudos de Coortes , Método Duplo-Cego , Emulsões Gordurosas Intravenosas/administração & dosagem , Emulsões Gordurosas Intravenosas/química , Humanos , Subpopulações de Linfócitos/imunologia , Distúrbios Nutricionais/complicações , Distúrbios Nutricionais/imunologia , Estudos Prospectivos , Fatores de Tempo , Triglicerídeos/administração & dosagem , Triglicerídeos/químicaRESUMO
The authors report the cases of two men with coronary artery disease by amiodarone for 8 and 24 months respectively. They developed clinical and radiological changes of diffuse interstitial pneumonia, characterised by an inflammatory syndrome, restrictive changes on spirometry, reduced CO transfer and abnormal blood gases. Broncho-alveolar lavage showed a lymphocytosis with a large quantity of iodine in the macrophages and the presence of amiodarone and its metabolite in the supernatant fluid. The responsibility of this drug is imputed and the patients were cured within 3 months of its withdrawal with regression of clinical, radiological, spirometric and control alveolar lavage abnormalities. A favourable outcome without steroid therapy is practically unknown in the literature. These cases illustrate the possible risk of alveolitis or diffuse interstitial pneumonia during long term amiodarone therapy, the pathogenesis of which is discussed: iodine overload, direct drug toxicity or an immunological mechanism.
Assuntos
Amiodarona/efeitos adversos , Benzofuranos/efeitos adversos , Pneumopatias/induzido quimicamente , Idoso , Humanos , Pneumopatias/diagnóstico , Pneumopatias/fisiopatologia , Masculino , Pessoa de Meia-IdadeRESUMO
A 33 year old female had febrile aplasia following a first chemotherapy treatment for acute T lymphoid leukaemia. She was transferred to intensive care for acute respiratory distress due to bilateral pneumonia with Stenotrophomonas maltophilia septicaemic shock. After an initial improvement with antibiotic treatment, she developed multiple necrotic cutaneous lesions. A skin biopsy showed the presence of Aspergillus flavus in large quantities in the vascular lumina. Echocardiography revealed a voluminous vegetation on the mitral valve supporting aspergillus endocarditis. Despite antifungal treatment, shock and coma developed rapidly. Cerebral CT scan suggested multiple septic emboli. Within several hours, the scenario progressed towards multiorgan failure leading the death of the patient. Aspergillus endocarditis is exceptional and usually only occurs in immunosuppressed patients. The diagnosis is difficult, and the prognosis is appalling with a mortality greater than 90% despite treatment.
Assuntos
Aspergilose , Aspergillus flavus , Endocardite/microbiologia , Valva Mitral , Adulto , Aspergilose/diagnóstico , Endocardite/diagnóstico , Feminino , Doenças das Valvas Cardíacas/diagnóstico , Doenças das Valvas Cardíacas/microbiologia , HumanosRESUMO
OBJECTIVES: A 1993-1995 three year epidemiological survey of home parenteral nutrition was performed through in France in approved centers for adults. METHODS: Data were retrospectively collected each year on a standardized questionnaire focussing on indications and short term outcome. RESULTS: All centers (n = 14) participated in the study and 524 new adult patients were recruited. The overall incidence was unchanged at 3.75 patients/10(6) adults. Indications for AIDS rose (8 to 18%) whereas other indications were stable. Prevalence increased by 19%: 4.40 adults/10(6) patients at 01.01.1996. At six months, the probability to stay on treatment was 19.5% for AIDS and cancer indications but 52% for others, whereas death rates were 59% and 9% respectively. CONCLUSIONS: For both cancer and AIDS indications, short-term treatment was due to a poor prognosis. For other diagnosis, complicated with a short bowel in 51% of cases, prognosis was excellent but associated with treatment dependency. The latter point focuses on the need for additional treatments in irreversible intestinal failure.
Assuntos
Pesquisas sobre Atenção à Saúde , Nutrição Parenteral no Domicílio , Síndrome da Imunodeficiência Adquirida/complicações , Adolescente , Adulto , Idoso , Certificação , França , Humanos , Pessoa de Meia-Idade , Neoplasias/complicações , Nutrição Parenteral no Domicílio/normas , Prognóstico , Qualidade da Assistência à Saúde , Estudos RetrospectivosRESUMO
A 40 year old woman suffered from respiratory insufficiency (arterial PaO2 = 47 mmHg) because of a chronic beryllium intoxication. On 6th June 1990, she underwent double lung transplantation with cardio-pulmonary bypass. Each lung was separately implanted via an extra-pericardial approach, and both bronchi were anastomosed at the hilum. On the seventh post operative day, a severe bilateral bronchial ischemia was noticed (black mucosa). Few weeks later, a diffuse bronchomalacia was noticed in the proximal and distal parts of both bronchial trees. To our knowledge, such a bronchial post-ischemic complication has never been reported. The explantation could be several added causes: imperfect preservation of the lung during harvesting, post operative pulmonary oedema, and operative use of an antifibrinolytic agent (aprotinin).
Assuntos
Beriliose/complicações , Broncopatias/etiologia , Transplante de Pulmão/efeitos adversos , Insuficiência Respiratória/cirurgia , Adulto , Beriliose/diagnóstico por imagem , Beriliose/cirurgia , Brônquios/irrigação sanguínea , Brônquios/patologia , Broncopatias/diagnóstico por imagem , Broncopatias/microbiologia , Broncopatias/patologia , Candidíase/complicações , Feminino , Humanos , Isquemia/complicações , Transplante de Pulmão/métodos , Necrose , Complicações Pós-Operatórias , Cuidados Pré-Operatórios , Radiografia , Insuficiência Respiratória/diagnóstico por imagem , Insuficiência Respiratória/etiologia , Infecções Estafilocócicas/complicações , Infecções Estafilocócicas/microbiologiaRESUMO
The shortage of organ donors has led to progressive softening of selection criteria for organ donation. We report on hepatic transplantation in a 55-year-old woman with primary biliary cirrhosis, whose donor was a 50-year-old heart transplant recipient who became brain stem dead, due to cerebral bleeding 8 months after transplantation. An orthotopic liver transplantation was performed. The postoperative course was uneventful and the recipient was alive and had normal liver function after a 42-month follow-up. Analysis of the literature included ethical consideration, potential hepatotoxic effects of immunosuppressive drugs and modification of the graft immunogenicity. It confirms that transplanted patients should not be a priori excluded from organ donation.
Assuntos
Morte Encefálica , Transplante de Coração , Transplante de Fígado , Hemorragia Cerebral/complicações , Ética Médica , Feminino , Seguimentos , Humanos , Imunossupressores/uso terapêutico , Cirrose Hepática Biliar/cirurgia , Pessoa de Meia-Idade , Doadores de TecidosRESUMO
A series of 28 patients suffering from neuromeningeal listeriosis is reported. This disease is consecutive to infection by Listeria monocytogenes--an ubiquitous and opportunistic Gram-positive bacillus--and has become a public health problem: its incidence is increasing and its prognosis is very severe despite the development of new bacteriological identification methods. Human beings are contaminated by food, which explains the frequent outbreaks of epidemics which are widely publicized, the infection being one of the consequences of the unprecedented development of the food industry and the cold food chain. The predominant clinical picture is one of non-specific meningoencephalitis. In about 50 percent of the cases the subjects infected are "immunodepressed" and/or more than 60 years' old. The diagnosis is difficult since the bacteriological identification is delayed (direct examination of the cerebrospinal fluid is rarely positive) and this fluid may be sterile (hence the value of blood cultures). A probability treatment therefore must be initiated before the diagnosis is confirmed if an unfavourable outcome is to be avoided. In Listeria monocytogenes infection cotrimoxazole administered alone seems to be a better antibacterial therapy than the reference ampicillin-aminoside combination.
Assuntos
Meningite por Listeria/tratamento farmacológico , Combinação Trimetoprima e Sulfametoxazol/uso terapêutico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Cefalosporinas/uso terapêutico , Quimioterapia Combinada , Eletroencefalografia , Feminino , Humanos , Masculino , Meningite por Listeria/líquido cefalorraquidiano , Pessoa de Meia-IdadeRESUMO
A 42-year-old patient with emphysema was hospitalized in the intensive care unit for an episode of acute respiratory failure. The patient became dependent on invasive mechanical ventilation and surgical lung volume reduction was performed. The indication of lung volume reduction in this pathological situation but was followed by rapid weaning 48 hours postoperatively. The patient was discharged without ventilatory assistance and has not required further ventilatory assistance after more than 2 years follow-up.
Assuntos
Enfisema/cirurgia , Pneumonectomia , Respiração Artificial/efeitos adversos , Doença Aguda , Adulto , Enfisema/patologia , Humanos , Masculino , Insuficiência Respiratória/terapia , Resultado do TratamentoRESUMO
Three cases of severe slow-release theophylline toxicity (plasma theophylline levels above 30 mg/l) in patients with severe chronic pulmonary disease are reported. Seizures were noted in all patients, and one had tachyarrhythmia. Two of the patients died. Several factors were present which may have impaired theophylline clearance, leading to toxic plasma levels. The mortality rate of theophylline intoxication being high, the initial doses should be sufficiently low to minimize the risk of adverse affects, and the best way to prevent theophylline toxicity is to monitor plasma concentrations. A management of patients with theophylline overdosage is suggested: oral administration of activated charcoal is the primary therapeutic measure; haemoperfusion or haemodialysis should be considered only in patients in whom conservative measures have failed.
Assuntos
Epilepsia/induzido quimicamente , Teofilina/intoxicação , Idoso , Idoso de 80 Anos ou mais , Carvão Vegetal/administração & dosagem , Preparações de Ação Retardada , Humanos , Masculino , Pessoa de Meia-Idade , Insuficiência Respiratória/tratamento farmacológico , Teofilina/sangue , Teofilina/uso terapêuticoRESUMO
Four patients in status asthmaticus and with alveolar hypoventilation were given a helium-oxygen (He-O2) mixture to breathe during 4 hours. Clinical improvement and return to normal of arterial blood gas levels were rapid and dramatic in all patients. The He-O2 mixture, which is a low density gas, causes a reduction in pulmonary resistance and an improvement in overall alveolar ventilation.