Utility of blood cultures in community-acquired pneumonia requiring hospitalization: influence of antibiotic treatment before admission

It has been previously shown that antibiotics given before hospitalization significantly reduce the proportion of positive blood cultures in community-acquired pneumonia (CAP). The aim of this prospective study was to compare the utility and cost-benefits of blood cultures in patients, hospitalized for moderate CAP, who had or had not received antibiotic therapy prior to admission. During 1 year, 53 patients were included and separated into two groups: group 1 patients had not received antibiotic treatment prior to admission (n = 30), whereas group 2 patients had been treated with antibiotics (n = 23). Within the first 48 hours, a set of blood cultures was collected if the body temperature was higher than 38.5 degrees C or in the case of shaking chills. A total of 136 blood cultures was collected; 74 in group 1 and 62 in group 2. Bacteraemia was significantly more frequent in group 1 than in group 2, 5/30 patients vs. 0/23, respectively (P < 0.05). The cost of negative blood cultures was valued at 13,939.2 FF in group 1 and 13,164.8 FF in group 2, respectively 464.6 +/- 244.3 FF and 569.3 +/- 233.4 FF per patient (n.s.). Moreover, blood cultures were the method of diagnosis in only one of the five patients with bacteraemia and in no case did a positive blood-culture result influence the initial therapeutic regime. Thus, our results suggest a reduced clinical utility and cost-benefit of blood cultures in patients hospitalized for moderate CAP who have received an antibiotic treatment prior to admission.

[Pulmonary cavitated opacity in immunocompromised patient]

Lung abscesses are uncommon in legionellosis and usually are observed in immunocompromised patients. The radiographic presentation may lead to misdiagnosis and subsequently to increased mortality.

Effectiveness of controlled and spontaneous modes in nasal two-level positive pressure ventilation in awake and asleep normal subjects

STUDY OBJECTIVES

The purpose of the present study was to compare in awake and asleep healthy subjects, under nasal intermittent positive pressure ventilation (nIPPV) with a two-level intermittent positive pressure device (two-level nIPPV), the efficacy of the controlled and spontaneous modes, and of different ventilator settings in increasing effective minute ventilation (VE).

PARTICIPANTS

Eight healthy subjects were studied.

SETTING

In the controlled mode, inspiratory positive airway pressure (IPAP) was kept at 15 cm H2O, expiratory positive airway pressure (EPAP) at 4 cm H2O, and the inspiratory/expiratory (I/E) time ratio at 1. The respirator frequencies were 17 and 25/min. In the spontaneous mode experiment, IPAP was started at 10 cm H2O and progressively increased to 15 and 20 cm H2O; EPAP was kept at 4 cm H2O.

MEASUREMENTS AND RESULTS

We measured breath by breath the effective tidal volume (VT with respiratory inductive plethysmography), actual respiratory frequency (f), and effective VE. Using the controlled mode, effective VE was significantly higher on nIPPV than during spontaneous unassisted breathing, except in stage 2 nonrapid eye movement sleep at 17/min of frequency; increases in f from 17 to 25/min led to a significant decrease in VT reaching the lungs, during wakefulness and sleep; effective VE was higher at 25 than at 17/min of frequency only during sleep; periodic breathing was scarce and apneas were never observed. Using the spontaneous mode, with respect to awake spontaneous unassisted breathing, two-level nIPPV at 10 and 15 cm H2O of IPAP did not result in any significant increase in effective VE either in wakefulness or in sleep; only IPAP levels of 20 cm H2O resulted in a significant increase in effective VE; during sleep, effective VE was significantly lower than during wakefulness; respiratory rhythm instability (ie, periodic breathing and central apneas) were exceedingly common, and in some subjects extremely frequent, leading to surprisingly large falls in arterial oxygen saturation.

CONCLUSIONS

It appears that two-level nIPPV should be used in the controlled mode rather than in the spontaneous mode, since it seems easier to increase effective VE with a lower IPAP at a high frequency than at a high pressure using the spontaneous mode. We suggest that the initial respirator settings in the controlled mode should be an f around 20/min, an I/E ratio of 1, 15 cm H2O of IPAP, and EPAP as low as possible.

[Tuberculosis of the breast]

The authors report a case of tuberculosis of the breast in a patient aged 71. The case described is an example of a rare form of extra pulmonary tuberculosis whose diagnosis can pose problems. In view of the recent increase in the incidence of tuberculosis in certain developed countries and the growth in the proportion of cases of extra pulmonary tuberculosis especially in HIV sero-positive individuals an observation such as this is useful in that it recalls for clinicians the fact that tuberculosis may present in very unusual forms which are easily forgotten.

Determinants of effective ventilation during nasal intermittent positive pressure ventilation

Our aim was to verify in healthy subjects submitted to nasal intermittent positive pressure ventilation (nIPPV) with a volumetric ventilator on controlled mode, whether changes in ventilator settings (delivered tidal volume (VT), respiratory frequency (fR) and inspiratory flow (V'I) could influence effective minute ventilation (V'E), thus allowing identification of the settings resulting in the highest V'E during nIPPV. We then compared these experimentally obtained "best" settings to those obtained retrospectively in a group of patients submitted to long-term nIPPV for clinical reasons. We studied 10 healthy subjects awake and asleep, and 33 patients with restrictive ventilatory disorders. Changes in delivered V'I (for a constant delivered VT and fR) led to significant changes in V'E. V'E was significantly higher when a given delivered V'E was obtained using higher fR and lower VT than when it was obtained using lower delivered fR and higher VT. Increases in fR generally resulted in increases in V'E. The "best" settings derived from these results were: VT: 13 mL.kg-1 of body weight; fR: 20 breaths.min-1 and V'I: 0.56-0.85 L.s-1. The corresponding average values found in the patient group were: delivered VT: 14 mL.kg-1; fR: 23 breaths.min-1 and delivered V'I: 0.51 L.s-1. Changes in minute ventilation resulting from modifications in ventilator settings can be attributed to the glottic response to mechanical influences. This leads to "ideal" settings quite different from the standard ones in intubated patients. Values derived from nasal intermittent positive pressure ventilation in healthy subjects seem to apply to patients submitted to long-term nasal intermittent positive pressure ventilation.

Nasal mask pressure waveform and inspiratory muscle rest during nasal assisted ventilation

In mechanically ventilated patients, pressure and flow tracings can be used to assess respiratory pump muscle activity or rest. When the ventilation is delivered through an endotracheal tube, the respiratory system can be considered a one-compartment model, and activation of the respiratory muscles results in deformations and variability of the pressure tracings. This is also true when mechanical ventilation is delivered nasally. With intermittent positive-pressure ventilation delivered through a nasal mask (nIPPV), we have recently shown that the glottis can interfere with ventilation even in the absence of diaphragmatic surface electromyographic (EMG) activity. On the basis of our observations, we suggested that when mechanical ventilation is delivered through a nasal means of access, the respiratory system cannot be considered a one-compartment model. To confirm this hypothesis, we submitted one healthy subject to nIPPV while his glottis was continuously monitored through a fiberoptic bronchoscope and his diaphragmatic activity was monitored with a bipolar esophageal electrode. During wakefulness or sleep, we observed irregularities in the nasal mask pressure waveform, in nasal mask peak pressure, and in actual VT despite the absence of respiratory pump muscle activity. These irregularities were related to significant variations in the glottic width, rather than to the reappearance of transient phasic inspiratory muscle activity. We conclude that during nIPPV, deformations in the mask pressure waveform can be induced by variations in the glottic aperture without activation of the diaphragm. Thus, when mechanical ventilation does not bypass the glottis, the respiratory system does not behave like a one-compartment model, and EMG remains the only reliable technique for assessing diaphragmatic muscle activity.

Glottic aperture and effective minute ventilation during nasal two-level positive pressure ventilation in spontaneous mode

Our goal was to verify glottic behavior and its effects on effective minute ventilation during intermittent positive pressure ventilation applied at increasing inspiratory pressure levels through a nasal mask (nIPPV) using a two-level positive pressure ventilator (two-level IPPV) in spontaneous mode. Ten subjects were studied while awake. The spontaneous mode was used at three levels of inspiratory positive airway pressure (IPAP): 10, 15, and 20 cm H2O. The expiratory pressure was kept at 4 cm H2O. Records of spontaneous breathing without nIPPV were also performed. The glottis was continuously monitored through a fiberoptic bronchoscope. We measured, breath by breath, the widest inspiratory angle formed by the vocal cords at the anterior commissure, the corresponding tidal volume (with respiratory inductive plethysmography), the respiratory frequency and other indices. Our data during wakefulness show that inspiratory pressures of 10 and 15 cm H2O did not result in increases in effective minute ventilation with respect to spontaneous breathing. Only at 20 cm H2O of IPAP did effective minute ventilation increase. This was due essentially to a decrease in respiratory frequency with increasing pressures, offsetting increases in tidal volume at 10 and 15, but not at 20 cm H2O of inspiratory pressure. Changes in end-tidal CO2 suggest that alveolar ventilation increased due to the change in breathing pattern. Contrary to what we observed previously with either two-level IPPV used in the controlled mode, or nIPPV performed with volumetric ventilators, the glottis did not play any noticeable role in the control of effective minute ventilation.

Progesterone treatment in chylothorax associated with pulmonary tuberous sclerosis

We report the case of a young woman with tuberous sclerosis who developed a chylous pleural effusion after several invasive procedures for treatment of recurring pneumothoraces. Oophorectomy was rejected by the patient and progesterone therapy initiated. Medroxyprogesterone acetate administration led to a complete disappearance of the chylothorax in 8 months. The patient was kept on therapy, and no recurrence of pleural effusion has been observed up to the present (22 months follow-up). However, a progressive deterioration in pulmonary function was observed, with a significant decrease in pulmonary transfer factor and increase in airway obstruction. In conclusion, this report demonstrates an objective benefit of progesterone therapy on chylous effusion associated with pulmonary tuberous sclerosis.

[Swyer-James or Macleod syndrome or unilateral translucent lung]

The syndrome, described by Swyer and James in 1953 and by Macleod in 1954 is a specific entity within a much larger group of radiological conditions brought together under the term of unilateral translucent lung. Generally acquired in childhood subsequent to viral bronchopulmonary infections, the syndrome is caused by predominantly unilateral obliteration of the distal bronchi. The lung is usually small as the infection during childhood inhibited the normal growth pattern. Two elements found in all patients are trapped air and distal bronchiol obstruction. Pulmonary vascularization is greatly reduced leading to radiological translucency. Clinical signs are usually absent. We report two cases illustrating late diagnosis in adults and focus on the novel aspects of this syndrome as well as recent pathogenic hypotheses and diagnostic approach.

Nasal two-level positive-pressure ventilation in normal subjects. Effects of the glottis and ventilation

The purpose of this study was to examine the behavior of the glottis during intermittent positive-pressure ventilation (nIPPV) using a two-level positive-pressure ventilator and to compare the glottic adaptation to this ventilatory mode with the one observed using volumetric ventilators, recently reported by us. Six healthy subjects were studied during both wakefulness and sleep. Their glottis was continuously monitored through a fiberoptic bronchoscope. We measured breath by breath the widest inspiratory angle formed by the vocal cords at the anterior commissure, the corresponding tidal volume, and other indices. We used the controlled ventilatory mode. The expiratory pressure was kept at 4 cm H2O, and the inspiratory pressure was increased by steps from 10 to 15 to 20 cm H2O. Increases in inspiratory pressure did not always lead to increases in effective ventilation reaching the lungs. This was due to a significant narrowing of the glottis by adduction of the vocal cords in all subjects. Periodic breathing with or without apneas were common during wakefulness, but especially during sleep, representing 10.5 +/- 11% (SD) of total sleep time. We conclude that effective ventilation during nIPPV using a two-level positive-pressure ventilator in the controlled mode is less predictable and less stable than during nIPPV using volumetric ventilators.

[Uncommon site of Bergeyella zoohelcum. Apropos of a case]

Bergeyella zoohelcum is a Gram negative bacillus which can be found in several pathological localizations in man: leg abscesses, septicemia, meningitis. We observed a case of community-acquired pneumonia caused by Bergeyella zoohelcum. On history taking it was found that the patient was exposed to a dog which may have been the carrier of the Gram negative bacilli. The clinical course was long, one year, with persistent excavation.

Oxygen cost of breathing in patients with emphysema or chronic bronchitis in acute respiratory failure

This study compared the oxygen cost of breathing (VO2 resp) in 19 patients with severe chronic obstructive pulmonary disease intubated for acute respiratory failure. Ten patients showed radiologic (X-ray and/or computed tomographic scan) evidence of emphysema. The remaining ones were considered as having chronic bronchitis. Measurements were made just before extubation. Despite similar expiratory airflow obstruction, patients with emphysema exhibited significantly higher VO2 resp than patients with chronic bronchitis (109 +/- 61 versus 42 +/- 26 ml/min/m2, respectively; p < 0.006). Moreover, emphysema was associated with nutritional depletion assessed through decreases in body mass index (emphysema: 17.9 +/- 3.5 kg/m2; chronic bronchitis: 28.8 +/- 8.2 kg/m2; p < 0.005). This seemed to affect somatic stores (significant decreases in arm muscular circumference and triceps skin-fold thickness, whereas visceral stores were preserved (no decreases in serum albumin, serum prealbumin, and retinol binding protein). Malnutrition appeared to be the consequence of a hypermetabolic state of the respiratory muscles, with a significant negative correlation between VO2 resp and body mass index, arm muscular circumference, and triceps skinfold thickness (p < 0.05). Total oxygen consumption normalized for body surface was similar in the two groups. Thus, in emphysematous patients, the oxygen available for tissues other than respiratory muscles was significantly reduced (emphysema: 124 +/- 51 ml/min/m2; chronic bronchitis: 207 +/- 78 ml/min/m2; p < 0.02). This could explain nutritional differences observed between patients with emphysema and those with chronic bronchitis.

Effects of nasal positive-pressure hyperventilation on the glottis in normal awake subjects

We have recently observed obstructive apneas during nasal intermittent positive-pressure ventilation (nIPPV) and suggested that they were due to hypocapnia-induced glottic closure. To confirm this hypothesis, we studied seven healthy subjects and submitted them to nIPPV while their glottis was continuously monitored through a fiber-optic bronchoscope. During wakefulness, we measured breath by breath the widest inspiratory angle formed by the vocal cords at the anterior commissure along with several other indexes. Mechanical ventilation was progressively increased up to 30 l/min. In the absence of diaphragmatic activity, increases in delivered minute ventilation resulted in progressive narrowing of the vocal cords, with an increase in inspiratory resistance and a progressive reduction in the percentage of the delivered tidal volume effectively reaching the lungs. Adding CO2 to the inspired gas led to partial widening of the glottis in two of three subjects. Moreover, activation of the diaphragmatic muscle was always associated with a significant inspiratory abduction of the vocal cords. Sporadically, complete adduction of the vocal cords was directly responsible for obstructive laryngeal apneas and cyclic changes in the glottic aperture resulted in waxing and waning of tidal volume. We conclude that in awake humans passive ventilation with nIPPV results in vocal cord adduction that depends partly on hypocapnia, but our results suggest that other factors may also influence glottic width.

Effects of nasal positive-pressure hyperventilation on the glottis in normal sleeping subjects

We have previously observed that, in normal awake subjects passively hyperventilated with intermittent positive-pressure ventilation delivered through nasal access (nIPPV), the glottis could interfere with the ventilation. We report on data obtained in the same subjects during stable sleep. In all cases, the glottis was continuously observed through a fiber-optic bronchoscope, and other indexes were also continuously recorded. Mechanical ventilation was progressively increased up to 30 l/min. We have observed during passive nIPPV in stable sleep that increases in delivered minute ventilation (VEd) resulted in progressive narrowing of the glottic aperture, with increases in inspiratory resistance and progressive reductions in the percentage of the delivered tidal volume effectively reaching the lungs. For a given level of VEd, comparisons showed that the glottis was significantly narrower during sleep than during wakefulness and that the glottis was significantly narrower during stage 2 than during stages 3/4 non-rapid-eye-movement sleep. Moreover, when CO2 is added to the inspired air, glottic aperture increased in five of nine trials without changes in sleep stage. We also observed a significant negative correlation between glottic width and the VED, independent of the CO2 level. We conclude that during nIPPV glottis narrowing results in a decrease in the proportion of the delivered tidal volume reaching the lungs.

Synchronized intermittent mandatory ventilation with and without pressure support ventilation in weaning patients with COPD from mechanical ventilation

This prospective study compared two weaning modalities in COPD patients requiring mechanical ventilation (MV) for acute respiratory failure. Nineteen patients with COPD were studied when their precipitating illness was controlled. Although they satisfied the conventional bedside weaning criteria, they could not tolerate any reduction in the respirator rate below 10 cycles/min. At this time, patients were randomized into two groups receiving either synchronized intermittent mandatory ventilation (SIMV) with pressure support ventilation (PSV) (group 1) or SIMV alone (group 2). The volumetric support of ventilation (SIMV rate) was progressively decreased in both groups according to the patient's tolerance with a concurrent decrease in the barometric support of ventilation (PSV levels from 15 cm H2O to 6 cm H2O). At each step of SIMV rate, we found no difference between group 1 and group 2 in arterial blood gases, blood pressure, heart rate, airway occlusion pressure, maximal inspiratory pressure, and oxygen cost of breathing (OCB). At each step, however, group 1 patients showed significantly higher spontaneous tidal volume and lower spontaneous breathing frequency than did group 2 patients. We found a slight but not significant tendency to a shorter weaning period with than without PSV, but no difference in the weaning success. We concluded that (1) conventional weaning criteria might be inaccurate in COPD patients, (2) SIMV appeared very useful in weaning COPD patients from MV, (3) PSV marginally reduced the weaning period when added to SIMV, and (4) the OCB was not significantly improved with PSV.

[Severe hypoxemia in cirrhosis]

Various respiratory signs (other than infectious pathology), either very frequent and mild or very rare but with a poor prognosis, can be observed in cirrhotic subjects. Hypoxemia raises the greatest diagnostic problems in these subjects. The poor homogeneity of ventilation-perfusion ratios is the most commonly proposed cause of hypoxemia in cirrhosis. In such cases, hypoxemia is typically moderate (60-80 mmHg). Conversely, anatomical shunts, especially intrapulmonary ones, account for severe hypoxemia (< 60 mmHg). We are reporting about the case of a severe form of hypoxemia without anatomical shunt, caused by an anomalous ventilation-perfusion ratio in a female patient with ethylic cirrhosis.

Influence of trigeminal nasal afferents on bulbar respiratory neuronal activity

This study examined the influence of nasal trigeminal afferents, the anterior ethmoidal nerve (AEN) and posterior nasal nerves (PNN) on the spike discharges of respiratory-related neurons recorded in the ventral respiratory group (VRG) (2.6-3.5 mm lateral to the midline, from 1 mm rostral to 3 mm caudal to the obex and at depth of 2-4 mm below the dorsal surface). Electrical stimulations to the AEN and PNN were administered to 10 pentobarbital anaesthetized cats and to 8 ketamine anaesthetized, vagotomized, curarized and ventilated cats. Single shock stimulations of either nerve evoked transient and total inhibition of inspiratory activities. Expiratory-related neurons of the VRG presented three patterns of activity in response to stimulation:excitation, inhibition or inhibition followed by excitation. More generally, expiratory units are activated with a short latency. In the course of repetitive stimulation of the AEN and PNN we observed a prolongation of the spontaneous inspiratory discharge which presented transient, short inhibition in response to each shock. Most expiratory units presented a short activation which was synchronous with the transient inhibition of inspiratory activities. When repetitive stimulation provoked a sneeze-like response, we observed a progressive increase in the duration of transient inspiratory inhibition first, associated with a progressive reinforcement of transient expiratory activation. Secondarily, just before the expiratory thrust, we noted a stronger inhibition of the inspiratory activity which preceded a high-frequency (400 Hz) expiratory discharge. Nasal afferents exert a forceful excitatory effect on bulbospinal (BS) and non-bulbospinal-non-vagal (NBS-NV) expiratory cells of the VRG. The effects due to vagotomy and curarization are discussed.

Trigeminal nasal receptors related to respiration and to various stimuli in cats

In twenty adult cats of either sex under nembutal anaesthesia, we aimed at delineating the sensitive territory of trigeminal nerves innervating the nasal mucosa. The different trigeminal nerves (anterior ethmoidal, posterior nasal and infraorbital nerves) were dissected in the orbit. Activity of these nerves was recorded during spontaneous nasal and tracheal breathing and in response to various stimuli: mechanical (manual probing and air jets) and irritants (ammonia vapours). Multiple and unitary activity recorded in nerve filaments enabled a classification of the receptors on the basis of their discharge pattern as rapidly-, intermediately- or slowly adapting receptors, and as drive or non-drive nasal receptors depending on whether or not the respiratory modulation was preserved during tracheal breathing.

Trigeminal afferences implied in the triggering or inhibition of sneezing in cats

The aim of this study was to precise the role of the different trigeminal nerve branches involved in innervation of the nostril in triggering the sneeze reflex. Electrical stimulation of the anterior ethmoidal, posterior nasal and infraorbital nerves was performed in anaesthetized cats. Stimulation of these 3 nerves produced sneezing identical to that induced by mechanical stimulation. Our results emphasize inhibition of the sneeze reflex related to stimulation of the anterior ethmoidal or the posterior nasal nerves by stimulation of the infraorbital nerve.

The SaO2/t diagram as a useful means to express nocturnal hypoxemia

The computerization of SaO2 recording during polysomnographic monitoring allows the construction of a diagram expressing the percentage of TIB spent at different steps in saturation. We studied the value of this diagram in three groups of male patients: (1) nine healthy subjects (all volunteers); (2) 25 patients with COPD who had a mean daily SaO2 of 92.3 +/- 1.3 percent; and (3) 25 patients with SAS who had a mean daily SaO2 of 92.1 +/- 1.4 percent. The results show the existence of a discriminating quality in the diagram's morphology, the existence of strong correlations (p less than 0.01) between the percentage of TIB spent at SaO2 less than 85 percent, and the total duration of the desaturation dips.

Selection of patients for long-term oxygen therapy (LTO)

Serial blood gas measurement must be made for at least three months following an acute exacerbation of chronic obstructive pulmonary disease, to secure stable arterial oxygen tension (PaO2) values. The borderline indications of oxygen therapy concern the patients who have PaO2 over 8 kPa (60 mmHg), but have nocturnal hypoxaemia and/or pulmonary hypertension. The indications of specific drugs such as almitrine are still subject to discussion. The presence of obstructive sleep apnoeas together with ventilatory troubles related to chronic obstructive lung disease (overlap syndrome), is associated with many diagnostic and therapeutic problems.