Orthodeoxia—An Uncommon Presentation following Bilateral Thoracic Sympathectomy

We present a case of orthodeoxia (postural hypoxaemia) which resulted from a combination of lung collapse/consolidation and blunted hypoxic pulmonary vasoconstriction due to partial interruption of the sympathetic nerve supply to the lung by bilateral thoracic sympathectomy

Doppler study of the effects of inhaled nitric oxide and intravenous almitrine on regional pulmonary blood flows in patients with acute lung injury

BACKGROUND

Lung ultrasound can be used at bedside to assess initial lung morphology in hypoxemic patients. We hypothesized that blood flow in consolidated lung and therefore effects of inhaled nitric oxide (iNO) and intravenous almitrine could be directly assessed using Doppler transesophageal echocardiography (TEE).

METHODS

We conducted a prospective study including 13 ALI patients with consolidated left lower lobe (LLL). Regional arterial and venous flow signals within the consolidation were recorded with TEE using Doppler at baseline, after iNO (5 ppm), almitrine (4 μg/kg/min) and their combination. Pulmonary shunt (Qs/Qt) was measured using a Swan-Ganz catheter. Arterial and venous velocity time integral (VTI), peak velocity (Vmax) and mean velocity (Vmean) were measured. Patients were responders if PaO2 basal value increased by 20% after iNO or almitrine.

RESULTS

In 7 NO responders, iNO decreased regional arterial VTI (8.1±1.9 vs. 6.7±1.6, P<0.05). In 8 almitrine responders, almitrine decreased regional arterial and venous VTI (from 6.7±2.0 to 4.5±2.3 cm and from 12.3±5.4 to 7.5±3.8 cm, respectively, P<0.05). For all patients, combination of iNO and almitrine decreased regional arterial and venous VTI (from 7.3±0.3 to 4.1±0.3 cm and from 12.6±0.7 to 6.7±0.8 cm, respectively, P<0.05). Arterial and venous Vmean and Vmax significantly decreased. Variations of arterial VTI and venous Vmean were correlated to variations of Qs/Qt (r=.71, P<.001 and r=.62, P<.01, respectively).

CONCLUSION

Doppler of consolidated LLL allows assessment of regional pulmonary circulation in ICU settings. It detects changes in flow profiles resulting from the administration of NO and/or almitrine. Further applicability remains to be determined.

Almitrine-Raubasine combination for dementia

BACKGROUND

Almitrine-raubasine combination (brand name Duxil), has been considered as an alternative treatment for dementia.

OBJECTIVES

To determine the clinical efficacy and safety of Duxil in the treatment of patients with dementia.

SEARCH STRATEGY

We searched the Cochrane Dementia and Cognitive Improvement Group Specialised Register (now known as ALOIS) (September 2009), the China Biological Medicine Database (CBM-disc 1979 to December 2009), the Chinese National Knowledge Infrastructure (www.cnki.net 1979 to December 2009), the Stroke Trials Registry at www.strokecentre.org/trials/index.aspx. We searched identified citations for additional trials, contacted the first author of identified trials for additional references and unpublished data. We also contacted the pharmaceutical company manufacturing Duxil (Servier Pharmaceutical Co Ltd) for additional unpublished data.

SELECTION CRITERIA

Randomised controlled trials studying the efficacy and safety of Duxil for dementia were included, irrespective of blinding, publication status, or language. If the trial was cross-over in nature, only data from the first period were included.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion, assessed trial quality and extracted the data.

MAIN RESULTS

Three trials involving a total of 206 participants were included, all patients with vascular dementia. All three included studies were assessed as being at high risk of bias. When analysing these trials together, there was significant beneficial effect of Duxil on the improvement of cognitive function measured by MMSE (WMD 2.04, 95% CI 1.43 to 2.66). No data on behaviour and death at the end of treatment and follow-up were available from the included trials. Two trials failed to show an improvement of functional performance measured by ADL (WMD -1.68; 95% CI -3.70 to 0.35). Of the three included trials, all described the adverse events in detail, there were no statistically significant differences across the trials (OR 4.84, 95%CI 0.55 to 42.67). Behaviour disturbance, quality of life, caregiver burden were not undertaken in the included trials.

AUTHORS' CONCLUSIONS

Due to the low methodological quality of included trials, small number of trials and probable publication bias, this review did not provide sufficient evidence to support the routine use of Duxil for the treatment of patients with dementia. High-quality and large-scale randomised controlled trials are needed to confirm or refute these results.

[Clinical research of effect of Yishen Yangnao capsule on vascular dementia]

OBJECTIVE

To find a good way to diagnose VD, value the effect of Yishen Yangnao capsule on VD and try to find some rules of changes in Chinese medicine syndromes.

METHOD

Patients were randomly divided into treating group and western medicine comparison group. It's the phase III clinical research of Rishen Yangnao capsule curing VD, judging the validity and security of it, using dukexi slice as comparison drug. Some of the patients did the examination of P300.

RESULT

The total validity of Yishen Yangnao capsule is 56.3% (contract team is 60.0%). The improve rate of ADL is 0.1069% (contract team is 0.1134%). The scores of Chinese medicine syndrome descend.

CONCLUSION

Yishen Yangnao capsule has the same effect as dukexi slice in curing VD at the side of intelligence situation and life ability.

Low- vs high-dose almitrine combined with nitric oxide to prevent hypoxia during open-chest one-lung ventilation

BACKGROUND

Almitrine combined with inhaled nitric oxide (NO) can prevent hypoxia during one-lung ventilation (OLV). The optimal dose of almitrine that would provide therapeutic advantage with few side-effects during open-chest OLV has not been established.

METHODS

Forty-two patients undergoing thoracotomy were randomly allocated to three groups: placebo, almitrine 4 microg kg(-1) min(-1) and inhaled NO 10 p.p.m. (ALM4+NO), and almitrine 16 microg kg(-1) min(-1) and inhaled NO 10 p.p.m. (ALM16+NO). Gas exchange, haemodynamic and respiratory variables and plasma concentrations of almitrine and lactate were monitored. Measurements were obtained with the patient awake (baseline), after induction of anaesthesia with two-lung ventilation (control 2LV), 20 min after treatment (2LV+T), and then at 10, 20 and 30 min of OLV (OLV10', OLV20' and OLV30') with FI(O2)1.

RESULTS

In the placebo group, OLV impaired Pa(O2) and increased pulmonary shunt [16 (SD 7) kPa and 42 (10)% respectively]. These improved with ALM4+NO [26 (10) kPa and 31 (7)%; P<0.001]. ALM16+NO further improved PaO2) to 36 (13) kPa (P<0.0001) but gave no improvement in the shunt. Mean pulmonary artery pressure was similar in the placebo and ALM4+NO groups [20 (4) vs 23 (5) mm Hg], whereas it was increased in the ALM16+NO group to 28 (8) mm Hg (P<0.01). Plasma concentrations of almitrine and lactate were unaltered by the treatments.

CONCLUSIONS

Low-dose almitrine (4 microg kg(-1) min(-1)) together with inhaled NO significantly improves oxygenation during open-chest OLV, without modifying pulmonary haemodynamics. An increased dose of almitrine (16 microg kg(-1) min(-1)) with inhaled NO further improves arterial oxygenation, but also increases mean pulmonary artery pressure.

Assessment of the therapeutic activity of a combination of almitrine and raubasine on functional rehabilitation following ischaemic stroke

BACKGROUND AND OBJECTIVES

Stroke is a major cause of disability. Certain experimental studies have suggested that a combination of almitrine + raubasine (Duxil) increases the supply of oxygen to cerebral tissues and may be beneficial in post-stroke rehabilitation. This multicentre clinical study was carried out in order to assess the efficacy of this combination on poststroke rehabilitation.

METHODS

The trial was a randomised, double-blind, placebo-controlled study. Patients that had experienced an ischaemic cerebrovascular accident (confirmed by CT scan) were included 4-6 weeks after the acute onset and received randomised treatment of either almitrine + raubasine or placebo 2 tablets daily for 3 months. Before treatment, there was a 2-week washout period for stopping all other drugs, except for antihypertensive and antidiabetic drugs. We assessed the patients by Barthel Index (BI), Neurological Functional Deficit Scores (NFDS), and Hasagawa Dementia Scales (HDS) each month after treatment.

RESULTS

A total of 83 patients were entered into the study and data were available for 74. Of these, 38 patients received almitrine + raubasine and 36 received placebo. The baseline characteristics were comparable between both groups. Almitrine + raubasine was significantly more effective than placebo at increasing BI at 1, 2 or 3 months (14.6 +/- 13.8 versus 3.3 +/- 13.2, p = 0.01; 19.3 +/- 13.6 versus 8.8 +/- 14.0, p = 0.02; 22.6 +/- 14.7 versus 10.7 +/- 17.0, p = 0.02 respectively) and reducing NFDS at 1 month (3.6 +/- 3.2 versus 1.9 +/- 3.5, p = 0.034) after treatment. More almitrine + raubasine-treated patients' NFDS had improved compared with placebo-treated patients at 2 and 3 months (97 versus 78%, p = 0.013; 100 versus 86%, p = 0.023 respectively). Compared with pretreatment, there was a strong tendency towards an improvement of HDS with almitrine + raubasine. The number of adverse events reported was low for the almitrine + raubasine-treated group and the placebo group and all events were mild, of short duration and resolved without treatment. Almitrine + raubasine had no clinically significant effect on blood pressure, heart rate or other laboratory tests.

CONCLUSION

The results indicate that almitrine + raubasine can accelerate neurological function recovery after stroke to some degree and is well tolerated.

Treatment of Hypoxemia During One-Lung Ventilation Using Intravenous Almitrine

We performed this prospective randomized double-blinded study to assess the ability of almitrine to treat hypoxemia during one-lung ventilation (OLV). Twenty-eight patients were anesthetized with propofol, sufentanil, and atracurium; lung separation was achieved with a double-lumen tube. A transesophageal Doppler probe was inserted to evaluate cardiac index. If SpO(2) was equal to or decreased to <95% during OLV (inspired fraction of oxygen of 0.6), patients were included in the study and received a placebo or almitrine (12 microg x kg(-1) x min(-1) for 10 min followed by 4 microg x kg(-1) x min(-1)) infusion until SpO(2) reached 90% or decreased to <90% (exclusion from the study). Eighteen of the 28 patients were included and received either almitrine (n = 9) or a placebo (n = 9). Treatment was discontinued in 1 patient in the almitrine group and 6 in the placebo group (P < 0.05). Treatment was successful (SpO(2) remaining >or=95% during OLV) in 8 patients in the almitrine group and 1 in the placebo group (P < 0.01). Heart rate, arterial blood pressure, and cardiac index did not change throughout the study, but we could obtain an adequate aortic blood flow signal in only half of the patients. Almitrine could be used to treat hypoxemia during OLV.

IMPLICATIONS

IV almitrine improves oxygenation during one-lung ventilation without hemodynamic modification. Such treatment could be used when conventional ventilatory strategy fails to treat hypoxemia or cannot be used.

Selective pulmonary vasodilation in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is characterized by a marked maldistribution of pulmonary perfusion in favor of nonventilated, atelectatic areas of the lungs, and it is the main cause of pulmonary right-to-left shunting and hypoxemia. Therapeutic interventions to selectively influence pulmonary perfusion in ARDS became feasible with the introduction of inhaled nitric oxide, which provided a means not only to reduce pulmonary hypertension, but also to improve matching of ventilation to perfusion and, thus, hypoxemia. Clinical studies in ARDS subsequently demonstrated that the combination of inhaled nitric oxide with other interventions, such as positive end-expiratory pressure and prone positioning, yielded beneficial and additive effects on arterial oxygenation. Although the available randomized, controlled trials of this novel concept have so far failed to show an improved outcome in ARDS, inhaled nitric oxide is a clinically valuable option for the treatment of severe refractory hypoxemia in ARDS, and largely promoted the concept of selective pulmonary vasodilation in intensive care practice. Currently, aerosolization of various vasodilators, in particular prostaglandins, is under evaluation in models of acute lung injury and human ARDS. Ongoing research aims to augment the effectiveness of vasodilators with specific inhibitors of phosphodiesterases or by combination with intravenous vasoconstrictors. Consequently, several alternative ways to selectively modulate pulmonary vascular tone in patients with ARDS may be available in the near future. Cost-benefit analysis of these therapeutic options will largely determine their future perspective.

[Effect of almitrine/raubasine on cerebral metabolism in the elderly]

Recent neurobiological data has led to renewed interest in oxygen (O2). The discovery of neuroglobin, protein varyingly present in the brain, has been enhanced by the elucidation of the mechanisms through which oxygen intervenes in neuronal metabolism. Almitrine/raubasine activates the metabolism of hypoxic/ischemic neurones by increasing O2 bioavailability. This mechanism supports the effects on behaviour obtained in various animal models and the benefits observed during clinical trials in elderly patients presenting with cognitive defects.

Association of oral almitrine and medroxyprogesterone acetate: effect on arterial blood gases in chronic obstructive pulmonary disease

Almitrine (A) and medroxyprogesterone acetate (MA) given separately improve arterial blood gases in some patients with chronic obstructive pulmonary disease (COPD); the aim of this study was to assess the effect of the two drugs given together. Forty-eight patients with irreversible COPD and hypoxaemia were prospectively enrolled into a 14-day run-in period and received single-blind oral treatment with double placebo. Patients whose PaO2 remained stable (less than 10% change; n = 29, 25 males, mean age 65.6 years) were included in a 14-day active treatment period and randomly assigned to three groups. They received double-blind oral treatment with: A (50 mg bid, group A, n = 10); MA (20 mg tid, group MA, n = 9); A (50 mg bid) and MA (20 mg tid, group A+MA, n = 10). Anthropometric and spirometric measurements were similar in the three groups and so were the arterial blood gas values at the beginning and the end of the run-in period. At the end of the active treatment period, blood gas changes (mean+/-SE) were significantly different between groups (P<0.05, Kruskal-Wallis test), with improvement in both hypoxaemia and hypercapnia in group A+MA only: delta PaO2 = 7.4+/-1.9 mmHg, delta PaCO2 = -5.1+/-1.7 m mHg (P<0.05, Wilcoxon test). In short-term treatment, the association of A and MA is more efficient than either drug alone at improving arterial blood gases in COPD patients.

Pharmacological features of an almitrine-raubasine combination. Activity at cerebral levels

Treatment with the combination of almitrine-raubasine increases both arterial oxygen partial pressure and haemoglobin oxygen saturation, reflecting an actual increase in the oxygen content of arterial blood. Furthermore, at the trans-cerebral carotid artery/internal jugular vein level, the treatment increases cerebral arterio-venous oxygen and glucose differences, suggesting an actual increase both in oxygen and glucose availability and uptake in cerebral tissues. The increased glucose transfer to the brain is supported also by enhancement of the 3H-deoxyglucose uptake induced by drug pre-treatment both in normoxia and hypoxia. Both almitrine and raubasine act at cerebral mitochondrial levels by decreasing the 'loss' of the 'biological' free energy for phosphorylation supported by the age-related drop in the cerebral enzyme activities, such as phosphofructokinase, pyruvate dehydrogenase and citrate synthase. Furthermore, the components interfere with the alterations induced by peroxidative stress acting at the level of cytochrome c, cytochrome c oxidase and succinate dehydrogenase. Treatment with the combination almitrine-raubasine increases the concentration of noradrenaline metabolites, while alteration of the dopaminergic system is less important. The interference with the noradrenergic system is possibly linked to the electroencephalographic changes induced by drug treatment: increasing alpha-rhythm distribution and reactivity, and increases in beta-rhythm amplitude. Pharmacological effects of almitrine-raubasine, obtained in experimental conditions, correlate with clinical therapeutic efficacy, e.g., in the treatment of cognitive disorders associated with ageing and other cerebral and neurosensory impairments. It is difficult to summarise, in a few pages, the large number of papers related to the cerebral pharmacometabolic and pharmacodynamic activities of the almitrine-raubasine combination. Thus, this review presents in sequential steps some of the interrelated research in humans and laboratory animals which describes in a critical way preclinical to clinical results.

Stroke and functional rehabilitation: the Chinese experience

According to an epidemiological study of cerebrovascular disease carried out in China in 1986, the prevalence, incidence, and mortality rates were 159.93/100,000, 115.61/100,000, and 31.33/100,000, respectively. These figures were high compared to available epidemiological data for the rest of the world. This highlights the fact that, as in other countries, functional rehabilitation after stroke is an important medical and social need in China. Clinical experience shows that within a few hours to a few months after a stroke, a large proportion of patients spontaneously experience partial, or on occasion, complete recovery from neurologic symptoms. However, functional rehabilitation in medical care units is required because it assists in and accelerates the recovery of impaired function. Almitrine-raubasine has been used to improve functional rehabilitation after stroke for some time in China. By enriching the oxygen content of arterial blood, it brings more oxygen to the cerebral tissues and therefore promotes cerebral aerobic metabolism during ischemia. In the acute phase of stroke, positron emission tomography showed, in man, that almitrine-raubasine helps normalize the ischemic penumbra area, as shown by an improvement in the coupling between oxygenation and perfusion. Long after stroke, single photon emission computed tomography showed that almitrine-raubasine restores normal cerebral vasodilator response to acetazolamide. With a view to further documenting the clinical efficacy of almitrine-raubasine on the convalescent period of patients with cerebrovascular disease, a double-blind, placebo-controlled study is planned. One hundred patients with ischemic cerebrovascular disease in the territory of the carotid artery will be included 4-6 weeks after the acute onset. Two tablets daily of almitrine-raubasine or placebo will be prescribed for 3-6 months. Before treatment, there will be a 2-week washout period for all other drugs, except for antihypertensive and antidiabetic drugs. In addition to complete clinical monthly examinations, neurological functional deficit scores, Barthel index, Hasagawa Dementia scales, and CT scan are scheduled. The study results should confirm those reported in the scientific literature: although untreated patients may show spontaneous improvement, almitrine-raubasine should accelerate patients' functional rehabilitation.

Clinical efficacy of almitrine-raubasine. An overview

Different pharmacological properties of almitrine-raubasine show that this combination may be a good therapy for the treatment of age-related cerebral disorders and functional rehabilitation after stroke. Many clinical studies have been carried out in France and in the rest of Europe, confirming the value of this compound in such situations. Without discussing the complexity of clinical trials in both the areas of cognitive disorders and stroke, we shall present two studies demonstrating the beneficial effects of almitrine-raubasine against cognitive impairments. The first is a double-blind controlled study versus placebo with a 3-month follow-up period involving patients (aged between 60 and 85) with memory loss, lack of concentration, impaired mental altertness, and emotional instability. The second is a controlled multicenter study of 155 outpatients (age 70-85) presenting with cognitive decline (assessed by MMSE, SCAG). In both these studies, almitrine-raubasine significantly improved symptomatology and was superior to placebo, especially in the vascular cases. This confirms the validity of previous studies and justifies the indication of these compounds in the treatment of age-related cognitive disorders. Other studies also demonstrated the beneficial effect of this compound on neurosensory vascular disorders, with specific studies carried out on chorioretinal dysfunctions (visual symptomatology) and in vestibular disorders (vertigo associated with electronystagmographic modifications). The appropriate and usual dosage (2 tablets per day) and the good tolerance of the compound have been confirmed in a French multicentric study in 5,361 outpatients.

Impact of sleep in COPD

Sleep has well-recognized effects on breathing, including changes in central respiratory control, airways resistance, and muscular contractility, which do not have an adverse effect in healthy individuals but may cause problems in patients with COPD. Sleep-related hypoxemia and hypercapnia are well recognized in COPD and are most pronounced in rapid eye movement sleep. However, sleep studies are usually only indicated in patients with COPD when there is a possibility of sleep apnea or when cor pulmonale and/or polycythemia are not explained by the awake PaO(2) level. Management options for patients with sleep-related respiratory failure include general measures such as optimizing therapy of the underlying condition; physiotherapy and prompt treatment of infective exacerbations; supplemental oxygen; pharmacologic treatments such as bronchodilators, particularly ipratropium bromide, theophylline, and almitrine; and noninvasive positive pressure ventilation.

[Intensive care and respiratory sleep disorders]

The study of respiratory sleep disorders in intensive care is a developing field. Indeed sleep pathology concerns not only pneumologists and neurophysiologists but also numerous specialties including medicosurgical resuscitation. The advent of "portable" appliances should facilitate access to polysomnography (PSG) for diagnosis of sleep respiratory disorders (RDS) in the intensive care unit. This examination can be appropriate in two separate circumstances. RDS in life-threatening situations (generally respiratory and/or cardiac failure) or when RDS is worsened by the specific conditions of intensive care units: "intensive care-induced RDS". In both cases, easy diagnosis of RDS by PSG allows adjustment of the treatment (corrections of iatrogenic factors, continuous positive airway pressure [CPAP], noninvasive ventilation [NIV], oxygen [O2]. A specific treatment of the well documented RDS is most desirable, as the patients are considered to be at high risk for endotracheal intubation. If diagnosis of RDS is not made during the acute phase, the intensive care physician should be informed of the clinical and paraclinical elements leading to prescription of a delayed polysomnography in order to reduce the risk of further vital distress.

Intravenous almitrine combined with inhaled nitric oxide for acute respiratory distress syndrome. The NO Almitrine Study Group

Inhaled nitric oxide (iNO), a selective pulmonary vasodilator and intravenously administered almitrine, a selective pulmonary vasoconstrictor, have been shown to increase PaO2 in patients with acute respiratory distress syndrome (ARDS). This prospective study was undertaken to assess the cardiopulmonary effects of combining both drugs. In 48 consecutive patients with early ARDS, cardiorespiratory parameters were measured at control, after iNO 5 ppm, after almitrine 4 micrograms. kg-1. min-1, and after the combination of both drugs. In 30 patients, dose response to 2, 4, and 16 micrograms. kg-1. min-1 of almitrine with and without NO was determined. Almitrine and lactate plasma concentrations were measured in 17 patients. Using pure O2, PaO2 increased by 75 +/- 8 mm Hg after iNO, by 101 +/- 12 mm Hg after almitrine 4 micrograms. kg-1. min-1, and by 175 +/- 18 mm Hg after almitrine combined with iNO (p < 0.001). In 63% of the patients, PaO2 increased by more than 100% with the combination of both drugs. Mean pulmonary artery pressure (Ppa) increased by 1.4 +/- 0.2 mm Hg with almitrine 4 micrograms/kg/ min (p < 0.001) and decreased by 3.4 +/- 0.4 mm Hg with iNO and by 1.5 +/- 0.3 mm Hg with the combination (p < 0.001). The maximum increase in PaO2 was obtained at almitrine concentrations <= 4 micrograms. kg-1. min-1, whereas almitrine increased Ppa dose-dependently. Almitrine plasma concentrations also increased dose-dependently and returned to values close to zero after 12 h. In many patients with early ARDS, the combination of iNO 5 ppm and almitrine 4 micrograms. kg-1. min-1 dramatically increases PaO2 without apparent deleterious effect allowing a rapid reduction in inspired fraction of O2. The long-term consequences of this immediate beneficial effect remain to be determined.

Inhaled nitric oxide, almitrine infusion, or their coadministration as a treatment of severe hypoxemic focal lung lesions

BACKGROUND

The partition of pulmonary blood flow between normal and shunting zones is an important determinant of oxygen tension in arterial blood (PaO2). The authors hypothesized that the combination of inhaled nitric oxide (iNO) and almitrine infusion might have additional effects related to their pharmacologic properties to improve PaO2. Such a combination was tested in patients with hypoxia caused by focal lung lesions, distinct from the acute respiratory distress syndrome.

METHODS

Fifteen patients with hypoxic focal lung lesions despite optimal therapy were included and successively treated with (1) 5 ppm iNO, (2) low-dose almitrine infusion (5.5 +/- 1.7 microg x kg(-1) min(-1)) during iNO, and (3) almitrine infusion alone (with NO turned off). Then iNO was reintroduced and we studied the effect of the coadministration in reducing the fractional concentration of oxygen in inspired gas (FI(O2)) and positive end-expiratory pressure (PEEP) levels. Changes in blood gases and pulmonary and systemic hemodynamics were measured.

RESULTS

Systemic hemodynamic variables remained stable in all protocol conditions. Use of iNO improved arterial oxygenation and decreased intrapulmonary shunt. Almitrine similarly improved PaO2 but increased pulmonary artery pressure and right atrial pressure. Coadministration of iNO and almitrine improved PaO2 compared with each drug alone and with control. All patients responded (that is, they had at least a +30% increase in PaO2) to this coadministration. When the drug combination was continued, FI(O2) and PEEP could be reduced over 8 h. The hospital mortality rate was 33% and unrelated to hypoxia.

CONCLUSIONS

In hypoxemic focal lung lesions, iNO or low-dose almitrine markedly improved PaO2 to a similar extent. Furthermore, the coadministration amplified the PaO2 increase at a level that allowed reductions in FI(O2) and PEEP levels.

Intravenous almitrine bismesylate reversibly induces lactic acidosis and hepatic dysfunction in patients with acute lung injury

BACKGROUND

Intravenous almitrine, which augments hypoxic pulmonary vasoconstriction, is used for short-term improvement of arterial oxygenation. However, recent research has suggested a potentially harmful effect on lactate metabolism and hepatic function.

METHODS

Arterial oxygenation, hemodynamic parameters, plasma lactate, and hepatic function were monitored prospectively in 25 patients with acute lung injury (defined as a ratio of arterial oxygen pressure to inspiratory oxygen fraction < or = 150 mmHg) who where treated with intravenous almitrine. In 21 of 25 patients, acute lung injury was related to primary lung lesions, including pneumonia, postcardiosurgical atelectasis, and lung contusions.

RESULTS

Intravenous almitrine increased the ratio of arterial oxygen pressure to inspiratory oxygen fraction from 93 +/- 33 mmHg to 207 +/- 107 mmHg (mean +/- SD). In eight patients (three men), the plasma lactate concentration increased by an average of +3.5 +/- 1.8 mM, and the pH and bicarbonate concentration both decreased during the first 24 h of treatment. In this group of patients, the total bilirubin concentration was elevated before almitrine administration, and the results of other hepatic function tests, such as aspartate aminotransferase, alanine aminotransferase, and prothrombin time, were altered by almitrine administration. Therefore, intravenous almitrine was discontinued. Lactic acidosis and hepatic dysfunction improved. In the other 17 patients (14 men), the plasma lactate concentration and the hepatic function tests remained unaltered during intravenous almitrine therapy for > 60 h. Univariate and multivariate analyses revealed that an abnormal plasma concentration of total bilirubin before almitrine administration and female gender were the two factors significantly linked with lactic acidosis during almitrine infusion.

CONCLUSIONS

This study confirms that intravenous almitrine greatly improves arterial oxygenation in patients with acute lung injury but may also induce lactic acidosis and hepatic dysfunction. The coexistence of lactic acidosis and hepatic dysfunction in the same patients strongly suggests that the liver is the primary source of intravenous almitrine-induced lactic acidosis.

The hypoxaemia in chronic obstructive pulmonary disease (COPD) and its management

Chronic hypoxaemia < or = 55 mmHg, induces various clinical and physiological consequences in patients with stable COPD: dyspnoea, decrease in exercise performances, erythrocytosis impairment of neuropsychological functions, pulmonary hypertension, right ventricular heart failure, all of these troubles impairing quality of life and vital prognosis. To restore a PaO2 > 60 mmHg (or SaO2 > 90%), long term oxygen therapy (LTOT) is the best method in the management of COPD with severe chronic respiratory failure. For patients with PaO2 55-70 mmHg. Almitrine bismesylate a piperazine derivative improving the ventilation/perfusion matching, used in low dosage and in sequential administration, is a useful drug to increase the PaO2 and so, to delay but not to avoid LTOT in responder patients when PaO2 remains < or = 55 mmHg.

Effects of almitrine bismesylate in a microswine model of hypoxemic hypothermia

We have developed an anesthetized microswine model of hypoxemic hypothermia and rewarming for testing prophylaxes and treatments. The respiratory stimulant almitrine bismesylate (ALM) was considered as a potential field expedient therapy for hypoxemic hypothermia. Preliminary experiments demonstrated that five consecutive 100 micrograms.kg-1 ALM intravenous (i.v.) doses given to normothermic microswine 3-4 min apart increased minute ventilation from an average of 3.4 L.min-1 to 4.5 L.min-1 (n = 2). However, when either a single i.v. ALM dose of 150 micrograms.kg-1 (n = 1) or three consecutive 100 micrograms.kg-1 i.v. doses given 15 min apart (n = 1) to hypoxemic hypothermic microswine with a mean esophageal temperature (Tes) = 28.8 degrees C, and a mean arterial O2 partial pressure (PaO2) = 49 mmHg, the hypoxemia was potentiated (mean PaO2 = 32 mmHg) and respiratory arrest ensued. Other experiments using continuous ALM i.v. infusion (1.0 microgram.kg-1.min-1) in hypoxemic hypothermic microswine (n = 6, Tes = 30.6 +/- 0.5, PaO2 = 55.4 +/- 12.9) did not demonstrate significant (p < or = 0.05) cardiorespiratory differences (ventilation, heart rate, blood pressure, blood gases) when compared to hypoxemic hypothermic controls (n = 6, Tes = 30.7 +/- 0.5, PaO2 = 53.3 +/- 13.6). These results suggest that high dose i.v. bolus administration of ALM is not indicated as a potential field expedient therapy for hypoxemic hypothermia, while further work is required to assess the potential efficacy of other continuous low dose i.v. infusion regimens.

[Pharmacologic treatment of hypoxemia in adult respiratory distress syndrome]

New drugs that improve arterial oxygenation (nitric oxide, almitrine, inhaled prostacyclin and cyclooxygenase inhibitors) are useful in the treatment of severe hypoxemia unresponsive to conventional treatment that is mainly seen in patients with acute respiratory distress syndrome (ARDS). By acting selectively on pulmonary blood flow and redistributing it, these drugs achieve effects unattainable until now. Thus, they decrease perfusion in non-ventilated zones (V/Q = O) responsible for shunt, or increase perfusion in well ventilated zones, guaranteeing adequate oxygenation. To apply these drugs the physician must understand their mechanism of action, guidelines for dosing, constraints on their use and side effects.

Additive beneficial effects of the prone position, nitric oxide, and almitrine bismesylate on gas exchange and oxygen transport in acute respiratory distress syndrome

OBJECTIVE

To test the hypothesis that prone position ventilation, nitric oxide, and almitrine bismesylate, each acting by a different mechanism to improve arterial oxygenation, could exert additive beneficial effects when used in combination in patients with severe acute respiratory distress syndrome (ARDS).

DESIGN

Prospective, nonrandomized, interventional study.

SETTING

Medical and surgical intensive care units at a university tertiary care center.

PATIENTS

Twelve patients with ARDS and severe hypoxemia, defined as PaO2/FIO2 of < or = 150 and FIO2 of > or = 0.6, with pulmonary artery occlusion pressure of < 18 mm Hg.

INTERVENTIONS

Inhaled nitric oxide (20 parts per million for 15 mins) in the supine and prone position, and intravenous almitrine bismesylate while prone (1 mg/kg/hr for 60 mins), alone or combined with nitric oxide.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic, blood gas, and gas exchange measurements were performed at sequential time points as follows: a) baseline supine; b) nitric oxide in the supine position; c) after return to baseline supine; d) after 30 mins prone; e) after 120 mins prone; f) nitric oxide while prone; g) after return to baseline prone; h) almitrine bismesylate prone; and i) nitric oxide and almitrine bismesylate combined, for 15 mins prone. Patients were considered responders to the prone position if a gain in PaO2 of > or = 10 torr (> or = 1.3 kPa) or a gain in the PaO2/FIO2 ratio of > or = 20 was observed. Seven patients (58%) responded to being turned prone. Compared with supine baseline conditions, nitric oxide and supine position increased arterial oxygen saturation from 89 +/- 1 (SD)% to 92 +/- 3% (p < .05) and nitric oxide plus prone position increased arterial oxygen saturation (94 +/- 3% vs. 89 +/- 4%, p < .05) and decreased the alveolar-arterial oxygen difference from 406 +/- 124 torr (54 +/- 15 kPa) to 387 +/- 108 torr (51 +/- 14 kPa) (p < .05). Almitrine bismesylate increased PaO2/FIO2 vs. baseline (122 +/- 58 vs. 84 +/- 21, p < .05). Almitrine bismesylate decreased the alveolar-arterial oxygen difference vs. baseline from 406 +/- 124 torr (53.9 +/- 16.5 kPa) to 386 +/- 112 torr (51.3 +/- 14.8 kPa) and vs. nitric oxide and supine position from 406 +/- 111 torr (53.9 +/- 14.7 kPa) to 386 +/- 112 torr (51.3 +/- 14.8 kPa) (p < .05). Prone position alone did not improve oxygenation. However, the combination of nitric oxide and almitrine bismesylate increased PaO2/FIO2 vs. nitric oxide supine and nitric oxide prone conditions (147 +/- 69 vs. 84 +/- 25 and 91 +/- 18, respectively; p < .05). In patients responding to the prone position (n = 7), combining nitric oxide and almitrine bismesylate led to further improvement in PaO2 compared with the prone position alone, with PaO2 increasing from 78 +/- 12 torr (10.3 +/- 1.6 kPa) to 111 +/- 55 torr (14.7 +/- 7.3 kPa) (p < .05), which was not the case when either nitric oxide or almitrine bismesylate was added separately. Heart rate and cardiac output were increased by almitrine bismesylate compared with all other measurements. Mean pulmonary arterial pressure was decreased by nitric oxide (27 +/- 7 vs. 30 +/- 7 mm Hg nitric oxide supine vs. baseline supine and 29 +/- 7 vs. 33 +/- 8 mm Hg nitric oxide prone vs. baseline prone, p < .05) and increased by almitrine bismesylate (36 +/- 9 vs. 30 +/- 7 mm Hg baseline supine, 27 +/- 7 mm Hg nitric oxide supine, 33 +/- 8 mm Hg baseline prone, and 29 +/- 7 mm Hg nitric oxide prone; p < .05). The increase in mean pulmonary arterial pressure was totally abolished by nitric oxide (31 +/- 5 vs. 36 +/- 9 mm Hg, p < .05). Minute ventilation, respiratory system compliance, physiologic deadspace, and PaCO2 remained unchanged.

CONCLUSION

In ARDS patients with severe hypoxemia, arterial oxygenation can be improved by combining the prone position, nitric oxide, and almitrine bismesylate, without deleterious effects.

Interest of a therapeutic optimization strategy in severe ARDS

STUDY OBJECTIVE

Evaluate the interest of the response to a therapeutic optimization as a predictor of prognosis in ARDS.

DESIGN

Prospective study.

SETTING

ICU of a University Hospital.

PATIENTS

Thirty-six consecutive patients with severe ARDS addressed for extracorporeal carbon dioxide removal (ECCO2R).

INTERVENTIONS

We studied the response during the first 2 days after arrival to the therapeutic optimization strategy consisting in a combination of the following: (1) decrease in extravascular lung water (diuretics or hemofiltration); (2) selection of the best ventilatory mode; (3) permissive hypercarbia; and (4) correction of hypoxemia by alveolar recruitment, additional continuous oxygen insufflation, body position changes (prone position), inhaled nitric oxide, enhancement of hypoxic pulmonary vasoconstriction with almitrine, and drainage of pleural or mediastinal effusions. In patients remaining severely hypoxemic despite these modalities, ECCO2R was then proposed.

MEASUREMENTS AND RESULTS

Thirty-six patients were addressed after 8.3+/-5.5 days of mechanical ventilation. On arrival, mean simplified acute physiologic score was 46.8+/-14.2, multiple system organ failure score was 1.8+/-1.6, Murray score was 3.4+/-0.4, PaO2 was 75.3+/-31.3 (fraction of inspired oxygen [FIO2]=1) for a positive end-expiratory pressure level of 12.3+/-3.4 cm H2O. Nineteen of 36 patients improved their gas exchange within 2 days and their mortality was 21%. The seventeen remaining patients did not improve PaO2/FIO2; PaCO2 and airway pressures remained high and their mortality was 88%. This different response to therapeutic optimization appeared using stepwise logistic regression as the most predictive factor for mortality (p<0.05).

CONCLUSIONS

In patients with severe ARDS, the response to an early performed therapeutic optimization used to improve hypoxemia appeared to be a highly discriminant factor distinguishing deceased from surviving patients.

Effects of almitrine on the ventilatory control, breathing pattern and maximal exercise tolerance in hypoxemic patients with chronic obstructive pulmonary disease

Almitrine bismesylate improves arterial blood gases in patients with chronic obstructive pulmonary disease (COPD), but side effects such as increase of ventilatory drive and dyspnea have been reported in some studies. We studied 18 COPD patients (mean age = 59.1 years; mean FEV1 = 0.92 1; mean PaO2 = 58.6 mmHg) in a double-blind randomized study using placebo or almitrine 50 mg twice a day by mouth, for 60 days. In contrast to the placebo group, 40% of the patients in the almitrine group presented a significant increase in PaO2 and a decrease in P(A-a)O2 > or = 5 mmHg during submaximal exercise after 60 days of treatment. Ventilatory drive and the breathing pattern were measured at rest and during submaximal exercise. Both groups showed high levels of ventilatory drive and a tachypneic breathing pattern before drug treatment and no modification was found 30 and 60 days after treatment. Metabolic, cardiovascular and ventilatory variables were studied during an incremental to maximum exercise symptom-limited test (cycloergometry). Maximal VO2 ranged from 46 to 52% and heart rate from 76 to 78% in relation to the predicted values. The percent ratio of ventilation at maximal exercise to maximal voluntary ventilation at rest ranged from 86 to 94%. These results show that the reduction of ventilatory capacity was the main factor decreasing the aerobic performance of our COPD patients. Maximal exercise tolerance (VO2 max) did not change after almitrine treatment. Negative factors like an increase in neuromuscular drive did not occur, and positive factors like an increase in PaO2 and oxygen transport had no critical influence on exercise performance in our ventilatory-limited COPD patients.

[Hepatopulmonary syndrome in decompensated cirrhotic patients]

Hypoxemia is common in cirrhotic patients and, when obvious pulmonary or cardiac causes are discarded, it is attributed to the so-called hepatopulmonary syndrome. The aim of this work was to assess the frequency of hypoxemia and orthodeoxia and its relationship with the degree of liver failure, in cirrhotic alcoholic patients. We studied 30 alcoholic cirrhotics. In all, arterial blood gases were measured in supine and standing positions, in 26 a chest X ray examination was done and in 20 a spirometry. Twelve patients had a subnormal PaO2 and this parameter fell more than 105 when assuming the standing position in one of these. The same reduction was observed in two subjects with normal supine PaO2. In the chest X ray examinations, pleural effusions were observed in five hypoxemic subjects and four with normal PaO2. Likewise minimal athelectasis was found in six and seven subjects and intestinal infiltrates in one of the two subjects. A significant association between hypoxemia and Pugh score was observed. Similarly, subjects with hypoxemia is frequent in alcoholic cirrhotic patients and, since it is not associated to obvious pulmonary causes, it may be attributed to the hepatopulmonary syndrome.

[Almitrine bismesylate treatment in chronic respiratory insufficiency]

This study was designed to evaluate the gasometric and functional respiratory responses in chronic bronchitic patients with chronic respiratory insufficiency (CRI) under ambulatory oxygen therapy (AOT) with almitrine bismesylate (AB). It was a double-blind, placebo-controlled, randomized, prospective study which lasted three months and with a dosage regime of 50-100 mg/day of AB. Fiftyfour patients completed the study (28 in AB and 24 in the placebo (P) groups, respectively). All patients were males, with a mean age or 65 +/- 6.1 years. In the study of pulmonary function only airway resistance (Raw) was changed, with a significant decrease at the third month in the AB group compared with the P group (0.83 +/- 0.31 vs. 1.07 +/- 0.46 kpa/L.S), with a p value of 0.05 (mean +/- SD) and PaO2 which improved from 8.15 +/- 0.88 to 8.81 +/- 2.3 kpa (61.17 +/- 6.6 to 66.10 +/- 10 mmHg), with a p value of 0.05. AB therapy was well tolerated.

[The predictive parameters in the response to almitrine treatment]

Almitrine bimesylate (AB) improves hypoxemia in an undetermined number of patients with respiratory failure. Our objective was to try to identify the patients likely to benefit from this treatment. We undertook a double blind study of AB (50-100 mg/day) vs placebo in 21 randomly chosen patients diagnosed as having chronic obstructive bronchitis who were receiving oxygen therapy in the home. The study lasted 3 months (T0 to T3). PaO2 rose from 51 +/- 5.3 to 58.5 +/- 10 mmHg (6.8 +/- 0.7 to 7.8 +/- 1.3 Kpa) in the 12 patients taking AB (p < 0.05). The remaining gasometric variables and results of functional respiratory exploration were unchanged. The 7 patients receiving AB who were defined as responding-whose PaO2 rose more than 5 mmHg (0.66 Kpa)-presented T0 values lower than those of the 7 non-responding patients in the same group, with respect to CO2 occlusion pressure, mean inspiratory flow and minute ventilation for both air and CO2. These variables can serve as predictors for gasometric response to AB.

[The effects of sodium nitroprusside and almitrine bismesylate on blood gases, hemodynamics and oxygen delivery in patients with cor pulmonale]

The effects of sodium nitroprusside and almitrine bismesylate on blood gases, hemodynamics and oxygen delivery were respectively studied in twenty-one and eighteen patients with cor pulmonale. The treatment of sodium nitroprusside resulted in significant decrease in pulmonary artery pressure. Although physiological shunt was increased (from 12.6 +/- 10.5 to 20.1 +/- 10.9%, P < 0.01) and arterial oxygen tension was decreased (from 12.6 +/- 4.0 to 9.9 +/- 2.5 kPa, P < 0.01) in patients undergoing mechanical ventilation, cardiac index (from 44.8 +/- 10.5 to 53.3 +/- 12.8 ml.s-1/m-2, P < 0.05) and oxygen delivery index (from 7.8 +/- 1.7 to 9.2 +/- 2.3 ml.s-1/m-2, P < 0.05) were improved. After treatment with almitrine bismesylate, improvement of arterial oxygen tension was observed in patients with spontaneous breathing (from 6.7 +/- 0.6 to 7.8 +/- 0.6 kPa, P < 0.05) and undergoing mechanical ventilation (from 10.9 +/- 1.9 to 13.4 +/- 2.5 kPa, P < 0.01), but increment of mean pulmonary artery pressure (from 3.8 to 0.5 and 3.1 +/- 0.8 to 6.3 +/- 0.7 and 3.6 +/- 0.9 kPa, respectively, P < 0.01) was noted.

Haemodynamics and gas exchange in liver cirrhosis: the effect of orally administered almitrine bismesylate

The present study was conducted to analyse the effect on haemodynamics and to evaluate the role of hypoxic pulmonary vasoconstriction (HPV) in cirrhotic patients with hypoxaemia using almitrine bismesylate, an agent which increases the response of HPV. Six male patients, mean age of 51 years, with hepatic cirrhosis and associated hypoxaemia were studied. All patients had normal lung and cardiac function tests. When the patients were clinically stable, right heart and radial artery catheterization were performed. Data from the pulmonary artery catheter and blood gases were obtained before and after 4 days of oral almitrine bismesylate. The results indicated that these cirrhotics were in a mild hyperdynamic circulatory state. The cardiac output (CO), cardiac index (CI), oxygen delivery (DO2), and oxygen consumption (VO2) were elevated while the pulmonary vascular resistance (PVR) and systemic vascular resistance (SVR) were low. Almitrine significantly increased PVR (P < 0.05) and mean pulmonary artery pressure (mPAP) (P < 0.01). In addition, almitrine improved alveolar arterial oxygen content difference [D(A-a)O2] (P < 0.01) and shunt fraction (Qva/QT) (P < 0.01). The PaCO2 and PaO2 increased slightly but this was not statistically significant. In conclusion, in our group of patients with hepatic cirrhosis, four days of treatment with almitrine improved their gas exchange. The data suggest a weak HPV response in this group of cirrhotics; that response may be enhanced by almitrine.

Acute and chronic effects of low dose almitrine bismesylate in the treatment of chronic bronchitis and emphysema

OBJECTIVES

Study of the acute and chronic effects of low-dose almitrine therapy in stable hypoxaemic patients with chronic bronchitis and emphysema.

METHODS

A low daily dose of 75 mg almitrine bismesylate was administered for six months in 23 patients with chronic bronchitis and emphysema. Nine patients (group 1) were placed on oral almitrine bismesylate 25 mg t.i.d. after they had received a single intravenous dose of 60 mg almitrine three months earlier. Fourteen additional patients, seven receiving almitrine (group 2) and seven placebo (group 3) were randomized for a 6 month double-blind evaluation of both acute and chronic effects of 75 mg almitrine on pulmonary gas exchange and on pulmonary haemodynamics. All patients were followed-up with regular measurements of blood gases, body plethysmography and with evaluation of peripheral nerve function.

RESULTS

Acute effects of almitrine were a significant increase in arterial oxygen tension by 14 mmHg after intravenous (p < 0.001) and by 15 mmHg after oral administration (p < 0.001), amelioration of hypercapnia, a slight transient increase in mean pulmonary artery pressure from 26 +/- 7 to 29 +/- 6 mmHg (NS) and a decrease of shunt due to improvement in ventilation/perfusion mismatching. In contrast, no acute changes in blood gases and pulmonary pressures were seen in the placebo group. A combination of almitrine with oxygen (8-10 L/min) was most effective in amelioration of hypoxaemia and shunt. With chronic almitrine therapy, the improvements in gas exchange persisted without elevation of pulmonary artery pressure (26 +/- 8 mmHg), whereas a negative trend in change of blood gases and pulmonary artery pressure occurred in the placebo treated group (NS). No significant changes in external ventilation, other spirometric parameters or adverse effects concerning peripheral nerve function were seen after almitrine or placebo treatment. The elimination of almitrine was fitted to a three compartment model and the terminal half-life in the patient population was found to be 32 +/- 29 days after intravenous dosing.

CONCLUSION

Acute and six-month almitrine bismesylate therapy at a low daily dose of 75 mg is found to be safe, even in severely compromised patients, with regard to pulmonary haemodynamics and peripheral nerve function. The agent is beneficial to pulmonary gas exchange, with reduction of hypercapnia, of intrapulmonary shunt and also with regard to sustained elevation of arterial oxygen tension. A combination with inhaled oxygen seems especially efficacious.

Sequential treatment with low dose almitrine bismesylate in hypoxaemic chronic obstructive airways disease

Daily dose schedules of 100-200 mg of almitrine bismesylate improve arterial blood gases in patients with hypoxaemic chronic obstructive airways disease (COPD) but dose related side effects are evident. In the present study, daily doses approximately half of those previously used were employed in a randomised double blind manner in 85 patients (age 35-79 years) with hypoxaemic COPD. After a one month period to check stability of arterial blood gases, patients were allocated to almitrine (A) or placebo (P) using an unequal code (60% A, 40% P). Tablets, 50-100 mg daily were stopped for one month after 3, 6 and 9 months to counteract drug accumulation. 50 patients in group A and 35 in group P were comparable on entry; mean age 65 (SD = 8) yrs., Pao2 7.8 (0.7) kPa (58.3 (5.0) mmHg), PaCO2 5.8 (0.8) kPa (43.2 (6.0) mmHg), forced expiratory volume in one second--FEV1 0.89 (0.25) l and 6 minute walking distance 296 (97) metres. The improvement in baseline PaO2 values was the same 0.8-1.3 kPa (6-9.8 mmHg) as with previous higher dose therapy. Approximately one third of patients did not respond, defined as PaO2 elevation > 0.67 kPa (5 mmHg). The sequential dosing scheme stabilised blood levels of almitrine within the therapeutic range of 280-300 ng.ml-1. After withdrawal of therapy arterial blood gases and spirometry reverted to pre-treatment levels, suggesting no permanent reversal of pathophysiology. Dose related side effects of breathlessness, indigestion and peripheral neuropathy were not observed. Nerve conduction studies revealed no difference in peripheral nerve dysfunction in hypoxaemic COPD between active and placebo therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparative study of the effects of almitrine bismesylate and lateral position during unilateral bacterial pneumonia with severe hypoxemia

The management of patients with unilateral pneumonia and severe hypoxemia often represents a therapeutic challenge. Mechanical ventilation with the diseased lung uppermost may improve gas exchange, but it is not devoid of adverse effects. No hemodynamic measurements have been reported in patients ventilated in this manner; therefore, whether or not the improvement in PaO2 is counterbalanced by hemodynamic deterioration remains unknown. Almitrine bismesylate is a drug that seems able to improve gas exchange in patients with chronic obstructive pulmonary disease or the adult respiratory distress syndrome. The increase in PaO2 after its administration has been attributed to an improvement in ventilation-perfusion relationships. Its use has never been reported during unilateral pneumonia with severe hypoxemia. We therefore compared its effects with those of lateral position in eight consecutive mechanically ventilated patients with unilateral pneumonia. Blood gas and hemodynamic measurements were performed both at maintenance FIO2 and at an FIO2 of 1.0. Almitrine (1 mg/kg over 1 h) had no effect on PaO2 under either FIO2 condition. Cardiac output remained unchanged, but mean pulmonary artery pressure increased from 22.5 +/- 1.2 to 26.5 +/- 1.3 mm Hg (p < 0.02). By contrast, lateral position had striking effects on PaO2, which increased from 100 +/- 14 mm Hg in supine position to 156 +/- 23 mm Hg (p < 0.01) when the abnormal lung was placed uppermost at maintenance FIO2 and from 207 +/- 21 (supine) to 300 +/- 28 mm Hg (lateral) (p < 0.01) at FIO2 1.0.(ABSTRACT TRUNCATED AT 250 WORDS)

Almitrine and doxapram in experimental lung injury

Almitrine and doxapram, two structurally unrelated peripheral chemoreceptor agonists, have been shown to enhance hypoxic pulmonary vasoconstriction in anesthetized dogs. We hypothesized that these drugs would increase pulmonary vascular tone and improve gas exchange in canine lung injury caused by oleic acid (OA). Pulmonary hemodynamics and gas exchange were investigated in pentobarbital-anesthetized dogs before and after intravenously administered OA 0.09 ml/kg and again after placebo (n = 6), almitrine 2 micrograms/kg/min (n = 6), or doxapram 20 micrograms/kg/min (n = 6) in a randomized order. Cardiac output (Q) was manipulated using a femoral arteriovenous bypass and an inferior vena cava balloon catheter to construct mean pulmonary artery pressure (Ppa)-Q plots in order to discriminate active from passive changes in Ppa. Gas exchange was assessed by measuring arterial PO2 and intrapulmonary shunt, determined using a sulfur hexafluoride infusion. OA increased Ppa over the range of Q studied, and it deteriorated gas exchange by an increase in intrapulmonary shunt. After OA, placebo had no effect on Ppa, arterial PO2, or intrapulmonary shunt. Both almitrine and doxapram further increased Ppa at all levels of Q studied, but they did not affect indices of gas exchange after OA. We conclude that in this experimental model of acute lung injury, almitrine and doxapram induce pulmonary vasoconstriction without, however, diverting blood flow toward better oxygenated lung regions.

[Effect of almitrine in acute canine lung injury induced by paraquat]

The effects of intravenously administered almitrine (0.3 or 1.0 micrograms/kg/min, for 30 min) on hemodynamics and pulmonary gas exchange were assessed in eight dogs with acute lung injury induced by paraquat under controlled ventilation. Arterial blood gases, pulmonary and systemic hemodynamics, and ventilation-perfusion distribution (VA/Q) using the multiple inert gas elimination technique were examined before (control) and during infusion of almitrine. Almitrine produced significant increases in mean pulmonary arterial pressure from 17.4 +/- 3.3 (control, mean +/- SD) to 20.4 +/- 1.5 mmHg (1.0 micrograms/kg/min), and in total pulmonary vascular resistance. There was no change in other hemodynamic parameters, arterial gas tensions, or VA/Q distribution. These results indicate that almitrine causes pulmonary vasoconstriction without changing ventilation-perfusion distribution in dogs with paraquat-induced lung injury.