Identification of the high-risk asthmatic patient. Experience with 39 patients undergoing ventilation for status asthmaticus.

Thirty-nine asthmatic patients required mechanical ventilation (IPPV) for status asthamticus over a seven and a half year period. We reviewed their clinical records with particular emphasis on the events leading to intermittent positive pressure ventilation (IPPV) and the long-term courses of those patients who survived IPPV. Long delays by patients before seeking medical attention, incomplete assessment of acute attacks, underuse of corticosteroids prior to admission and overuse of sedation were important factors often influencing the necessity for IPPV. Four patients died during IPPV. Of the 35 who survived, 32 were regularly followed in our Respiratory Clinic. Nine patients subsequently died, eight undoubtedly from asthma. Serial measurements of forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) were retrospectively analyzed to determine patterns of asthma. Of the 23 patients still alive, 14 have well controlled asthma, five have a pattern of persistent airflow obstruction, two have markedly labile asthma, and two have gradually deteriorating airflow obstruction. By contrast, seven patients who died sufficiently long after IPPV to enable categorization of their patterns showed either markedly labile asthma or gradually deteriorating airflow obstruction. None had relatively constant ventilatory function at either normal or suboptimal levels. We suggest that patterns of asthma are useful guides in detecting patients at high-risk. Patterns characterized by markedly labile asthma or gradually deteriorating airflow obstruction appear to be associated with an increased risk of sudden death from asthma.

Prophylactic use of the new quinolones for prevention of nosocomial infection in the intensive care unit.

The new quinolone antimicrobial agents, particularly those with less activity against anaerobes, selectively prevent colonisation of the alimentary tract by Gram-negative bacilli and staphylococci without substantially affecting the normal anaerobic flora, which preserve the colonisation resistance of the gut. These properties ideally position this class of antibacterial agent for selective decontamination of the digestive tract (SDD) in the prevention of nosocomial infection. The rationale for this procedure is based on the presumption that a significant proportion of infections in compromised patients are endogenous in origin, arising from the host's own microbial flora. If this colonisation by potentially pathogenic microflora within the normal flora can be significantly reduced without being replaced by other more pathogenic microorganisms, the risk of endogenous infection should be minimised. The quinolones have proved to be ideal agents for use in preventing infection in bone marrow transplant and other neutropenic patients. They have been used for SDD in the general intensive care unit population, although the technique has not received widespread acceptance. There have been only 4 reported randomised studies using quinolones as part of SDD regimens and only 301 patients have been evaluated. Although the incidence of ventilator-associated pneumonia has been significantly reduced from 36 to 15%, no effect has been shown on mortality. The cost of using SDD is significantly less with the quinolones than with other regimens, and induction of resistance has not been noted. The new quinolones, and in particular the more recently developed agents with extended Gram-positive activity, appear to be ideally suited for SDD, and their careful evaluation in further large, well designed trials is warranted.

Neurologic disease requiring long-term ventilation. The role of selective decontamination of the digestive tract in preventing nosocomial infection.

STUDY OBJECTIVE: To evaluate the efficacy of the technique of selective decontamination of the digestive tract (SDD) in preventing secondary infections in patients with neurologic diseases requiring intensive care. DESIGN: Randomized, double-blind, placebo-controlled trial using amphotericin B, polymyxin E, and tobramycin applied to the oropharynx and enterally; all patients received intravenous cefotaxime for 72 h. SETTING: Respiratory ICU. PATIENTS: Forty patients with neurologic diseases requiring ventilation for > 48 h and ICU stay > 5 days. Neurologic diagnosis included acute inflammatory demyelinating neuropathy (15), meningoencephalitis (10), status epilepticus (6), tetanus (6), and myasthenia gravis (3). INTERVENTIONS: Microbiologic surveillance samples of oropharyngeal and tracheal secretions, gastric aspirates, stool, urine, and any other potentially infected sites were taken at the time of ICU admission and twice weekly thereafter until 3 days after discharge from the unit. The SDD was applied every 6 h to the oropharynx and enterally. MEASUREMENTS AND RESULTS: Effective decontamination of the gastrointestinal tract was achieved in the patients receiving the active regimen; however, there was no reduction in the incidence of infections (11 in the active group vs 10 in placebo), and duration of ICU stay (30.1 +/- 22.5 vs 20.6 +/- 17.7 days) and hospital stay (49.3 +/- 31.9 vs 40 +/- 33.4 days) were unaffected as was the mortality (15 percent vs 15 percent). CONCLUSIONS: SDD did not reduce the incidence of secondary infection in patients with neurologic disease, nor did it affect morbidity or mortality; however, it adds considerably to the cost of patient care.

Etiology and diagnosis of pneumonia requiring ICU admission.

The spectrum of pathogens and the microbiologic investigations used to obtain a diagnosis in 178 patients with severe pneumonia (88 percent requiring intermittent positive-pressure ventilation) are reviewed. Ninety-five patients had primary pneumonia, 31 had nosocomial pneumonia, 24 were immunocompromised patients, and 28 had aspiration pneumonia. While the spectrum of isolates conformed to the usual patterns for the different types of pneumonia, the incidence of Gram-positive infections (15 percent), predominantly Klebsiella pneumoniae, Staphylococcus aureus, (8 percent), and Legionella pneumophila (5 percent) in primary pneumonia was much higher than in community or general hospital-based studies, and only one case of Mycoplasma pneumoniae was identified. Gram stain of sputum or tracheal aspirate taken on intubation in primary pneumonia was reliably predictive of the causative organisms in both Gram-positive and Gram-negative infections when compared with infections proven by blood culture. Serologic studies were valuable in patients in whom no positive microbiologic diagnosis was evident; however, fiberoptic bronchoscopy contributed minimally to the microbiologic diagnosis in this group of patients. The cause of severe primary pneumonia differs from less severe disease, and this should be recognized when selecting empiric antibiotic therapy.

Severe pneumococcal pneumonia complicated by massive pulmonary gangrene.

Massive pulmonary gangrene is a rare complication of pneumonia, particularly in the postantibiotic era. We report two cases of community-acquired Streptococcus pneumoniae pneumonia in young patients with a background of heavy alcohol abuse, but no other preexisting disease, which failed to respond to appropriate antibiotic therapy and intensive care. In both, there was extensive unilateral involvement, with initial dense consolidation followed by cavitation, but the previously reported classic later radiologic feature of coalescence into a large cavity with free-floating slough was not seen. Owing to ongoing sepsis with the development of multiple organ failure and the obvious failure of appropriate medical therapy, both patients underwent pneumonectomy with a successful outcome. These cases serve to emphasize the role of surgery in the management of massive pulmonary gangrene.

Surgical drainage of lung abscess complicating acute community-acquired pneumonia.

Two cases of severe community-acquired pneumonia requiring IPPV and complicated by the development of lung abscess were successfully treated with early surgical drainage. This procedure may be a life-saving measure in certain instances.

The etiology and antimicrobial susceptibility patterns of microorganisms in acute community-acquired lung abscess.

OBJECTIVE: To determine the spectrum and antibiotic susceptibility patterns of microorganisms causing acute community-acquired lung abscess. DESIGN: A prospective survey. SETTING: Medical emergency department and wards of a tertiary teaching hospital. PATIENTS: Thirty-four adult patients with both clinical and radiologic features compatible with a diagnosis of acute community-acquired lung abscess who had received less than 48 h of antibiotic therapy. INTERVENTIONS: Microbiologic specimens obtained by percutaneous lung aspiration and with a protected specimen brush via fiberoptic bronchoscopy were submitted for aerobic and anaerobic culture. MAIN OUTCOME MEASURES: Identification of all microorganisms, including anaerobes, and determination of antibiotic susceptibility. RESULTS: A mean of 2.3 bacterial species per patient was isolated, anaerobes alone being isolated in 44% of cases, aerobes alone in 19%, and mixed aerobic and anaerobic isolates in 22%. Aerobic Gram-negative pathogens were uncommon. In seven patients, Mycobacterium tuberculosis was identified; in two it was associated with other bacteria. In four patients, no organisms were isolated. All the nonmycobacterial isolates were susceptible to amoxicillin-clavulanate and in addition the anaerobes were all susceptible to chloramphenicol and almost all to a combination of penicillin and metronidazole. Among the anaerobes, the level of resistance to penicillin, metronidazole, and clindamycin individually was 21%, 12%, and 5%, respectively. CONCLUSIONS: Community-acquired acute lung abscess is usually caused by multiple anaerobic and less frequently aerobic Gram-positive microorganisms, which should respond to empirical therapy with amoxicillin-clavulanate, chloramphenicol, or a combination of penicillin and metronidazole. Tuberculosis, which may be indistinguishable from an acute lung abscess, occurred in 21% of patients in our study. Most bacterial pathogens are sensitive to conventional antimicrobial therapy and further investigation with percutaneous lung aspiration or bronchoscopy is indicated only when there is lack of early response to therapy or there is the presence of atypical clinical features.

Automatic weaning from mechanical ventilation using an adaptive lung ventilation controller.

STUDY OBJECTIVE: To evaluate a new method of closed-loop mechanical ventilation using an adaptive lung ventilation (ALV) controller in patients with different pathologic causes of respiratory failure at a time when they first met standard weaning criteria. STUDY DESIGN: Prospective, open, selected case study. SETTING: The 10-bed, multidisciplinary respiratory intensive care unit at Groote Schuur hospital, which is a teaching unit of the University of Cape Town. PATIENTS: Twenty-seven patients (9 patients in each of 3 groups: normal lungs, parenchymal lung disease, and COPD) who required prolonged mechanical ventilation and who met standard weaning criteria were included. Our institutional committee for ethical research approved the study and informed consent was obtained. INTERVENTIONS: The patients were mechanically ventilated and had daily measurements of vital capacity, respiratory rate, and arterial blood gas analysis until they met standard weaning criteria. On the day that each patient met the weaning criteria, a closed loop control algorithm providing ALV was implemented on a modified ventilator (Hamilton AMADEUS) with a PC-based lung function analyzer. After measuring gross alveolar ventilation, patients were placed in ALV and ventilatory and hemodynamic parameters were measured at baseline, 5 min, 30 min, and 2 h. Pertinent parameters measured included airway pressures, pressure support levels, respiratory rates, rapid shallow breathing indices, airway resistance indices, and patient respiratory drive and work indices. MEASUREMENTS AND RESULTS: In 22 patients, ALV reduced pressure support to 5 cm H2O and an intermittent mandatory ventilation rate of 4 breaths/min within 30 min, and all but 1 of these patients were successfully extubated within 24 h. In four patients, pressure support was maintained by ALV at a mean level of 14.6 cm H2O +/- for 2 h and these patients were recorded as having failed to wean. There was a measurable difference in an index of airway resistance relative to muscular activity between the successfully weaned and failed wean patients with COPD during the attempted wean by the ALV controller. CONCLUSIONS: ALV will provide a safe, efficient wean and will respond immediately to inadequate ventilation in patients when standard weaning criteria are met.

Anaplastic large-cell Ki-1 lymphoma. Pulmonary presentation mimicking miliary tuberculosis.

An unusual presentation of anaplastic large-cell (ALC) Ki-1 lymphoma is described, in which pulmonary involvement mimicked miliary tuberculosis. Lung involvement is uncommon in this type of lymphoma, and it is not clear from previous reports whether this was a presenting feature. Bone marrow involvement, rare in Ki-1 lymphoma, also was present in this case. Despite therapy skin involvement subsequently developed, and the patient died 3 months after presentation. Postmortem examination revealed lymphomatous involvement of the heart, liver, kidneys, stomach, and lymph nodes. This case highlights the need for awareness of ALC Ki-1 lymphoma particularly when it presents at uncommon extranodal sites.

The intensive care management, mortality and prognostic indicators in severe community-acquired pneumococcal pneumonia.

OBJECTIVE: To determine mortality and factors that might predict outcome in severe community-acquired pneumococcal pneumonia treated by a standard protocol. DESIGN: Prospective, non-concurrent study. SETTING: Respiratory intensive care unit (ICU) in a teaching hospital. PATIENTS: 63 patients who were diagnosed by positive blood culture or Gram stain and culture of sputum or tracheal aspirate were included. MEASUREMENTS AND RESULTS: Clinical features, severity scores including Acute Physiology and Chronic Health Evaluation (APACHE) II, organ failure and lung injury scores, and the clinical course in the ICU were documented; 79% of patients required mechanical ventilation. Bacteraemia was present in 34 patients (54%); there were no distinguishing clinical features between bacteraemic and non-bacteraemic cases. The overall mortality was 21%, with only 5 deaths (15% mortality) in the bacteraemic group. Shock and a very low serum albumin (< 26 g/l) were the only clinical features that differentiated survivors from non-survivors; lung injury, APACHE II and multiple organ failure scores were all predictive of outcome. The positive predictive value and specificity in predicting death in individuals for the modified British Thoracic Society rule 1 were 26 and 64%; APACHE II > 2057 and 88%; > 2 organ failure 64 and 92%; and lung injury > 233 and 73%, respectively. CONCLUSIONS: These results suggest that even in bacteraemic cases mortality should be below 25% with intensive care management and that conventional scoring systems, while predictive of group mortality, are unreliable in individuals.

Intensive care management of varicella pneumonia.

To determine the clinical features, treatment and outcome of severe varicella pneumonia with hypoxic respiratory failure requiring intensive care management, a prospective survey of consecutive cases was undertaken. Fifteen consecutive adult cases of varicella pneumonia with respiratory failure admitted to a 10-bed respiratory intensive care unit over a period of 10 y from 1984-1993 were studied. All patients were given acyclovir immediately on admission. The level of ventilatory support needed was determined by the severity of gas exchange abnormality, and varied from face mask oxygen (three patients), through continuous positive airway pressure (CPAP) by face mask (eight patients), to continuous positive pressure ventilation (CPPV) (four patients). The majority of patients were young females, only one of whom was pregnant. All patients had been in close contact with a known case of chickenpox. All patients responded well to acyclovir and ventilatory support with improved oxygenation. Monitoring with pulse oximetry was important to detect episodes of desaturation on inadvertent discontinuation of positive and expiratory pressure (PEEP). Two patients were admitted with bacterial superinfection, and one patient, who had required intubation and CPPV, developed nosocomial respiratory tract infection. There were no deaths. This experience suggests that intensive care admission, with the early administration of intravenous acyclovir and recognition of the severity of the hypoxaemia resulting from varicella pneumonia (which can be reversed with PEEP), should reduce the mortality of severe varicella pneumonia in adults.

Intensive care management of community-acquired Klebsiella pneumoniae.

The clinical features of 18 patients with Klebsiella pneumoniae requiring intensive care unit (ICU) management are presented. All patients required ventilatory support; 17 were given constant positive pressure ventilation and 10 required greater than 10 cm positive end expiratory pressure. The clinical picture was characteristic: pre-existing medical disease, clinical features of severe pneumonia and copious purulent bronchial secretions, Gram--ve organisms on Gram's stain and lobar consolidation on the chest radiograph were common. Septicaemic shock, confusion and uncompensated metabolic acidosis were the presenting clinical features predicting a poor outcome. Antimicrobial chemotherapy, that combined an aminoglycoside and a third generation cephalosporin to ensure adequate early antibiotic serum levels, may help to improve the prognosis.

Experience with fibreoptic bronchoscopy in the diagnosis of pulmonary shadows in renal transplant recipients over a 12-year period.

Despite improvements in immunosuppressive therapy, pulmonary infections remain an important cause of morbidity and mortality in renal transplant recipients. Over a 12-year period (1 January 1977 to 31 December 1988) we prospectively assessed the value of fibreoptic bronchoscopy in diagnosing radiographic pulmonary shadows in this group of patients. Forty-eight bronchoscopies were performed on 46 patients. A definitive diagnosis was established in 28/48 (58%) procedures (and was partially definitive for one of two organisms ultimately identified in another). The procedure failed in 19/48 (40%), although in 15 of these, the radiographic shadows resolved on antibiotics (9) or spontaneously (3) or autopsy revealed acute pneumonia (3). In four instances a specific diagnosis was made by alternative means. Clinically useful information which led to changes in management was obtained in 17/48 (35%) procedures and bronchoscopy was thought to have favourably influenced survival in 16/48 (33%). Fibreoptic bronchoscopy is in our experience a safe (only one pneumothorax and no significant haemorrhage) and useful technique in evaluating pulmonary shadows in renal transplant recipients.

Inappropriate ADH secretion in tetanus.

Of 99 patients with adult tetanus, 7 developed the clinical and biochemical features of the syndrome of inappropriate antidiuretic hormone secretion (SIADH). The diagnosis for these 7 patients was severe tetanus (dysphagia with frequent severe spasms); 5/7 patients had evidence of autonomic overactivity (tachycardia, sweating, cardiovascular lability, and hypersalivation). They all responded favorably to fluid restriction, SIADH was self-limited and resolved as the disease regressed.

Postoperative pulmonary morbidity.

Postoperative pulmonary complications, the most common of which are atelectasis and pneumonia, are due largely to the pathophysiological effects on the lungs of anaesthesia and surgery as well as pre-existing disease, in particular chronic obstructive airways disease (COAD). Pre-operative assessment, including pulmonary function tests, will allow the prediction of the risk of pulmonary complications. Active measures can then be introduced to reduce these complications.

Pefloxacin therapy for nosocomial infections in the intensive care unit.

Nosocomial infections occurring in an intensive care unit (ICU) are commonly caused by aerobic Gram-negative bacilli or Staphylococcus aureus, which are frequently multi-resistant and difficult to treat and contribute significantly to the patients' morbidity in the ICU. Pefloxacin, with its wide range of antimicrobial activity, lack of serious side-effects and advantageous kinetics, is a useful drug for use in this group of critically ill patients. Pefloxacin has achieved a greater than 70% clinical cure rate and a microbiological response of over 80% in cases of nosocomial pneumonia in the ICU. Failure and superinfection has occurred with the development of resistance, particularly in Pseudomonas aeruginosa in a small number of cases, but this can be prevented by combination antimicrobial therapy. Serious side-effects, including confusion, psychiatric disturbance and other neurological abnormalities were rare and resolved on withdrawal of the drug. Drug interactions occur with cimetidine and theophylline but are usually not clinically relevant; significant interaction with warfarin occurs and the dose of warfarin needs careful adjustment. Pefloxacin is a valuable drug for use in bacteriologically proven sensitive infections and combination with aminoglycosides or beta-lactam agents should prevent the development of resistance.

Is there a role for selective decontamination of the digestive tract in primarily infected patients in the ICU?

The role of selective decontamination of the digestive tract (SDD) for the prevention of nosocomial infection in critically ill patients remains controversial, and the efficacy of this technique in patients who are already infected on presentation to the intensive care unit has not previously been assessed. We performed a double-blind randomized placebo controlled trial of SDD (parenteral cefotaxime, six-hourly oral and enteral polymyxin E, tobramycin, and amphotericin B vs placebo) for all infected patients presenting to the ICU requiring mechanical ventilation for more than 48 hours and ICU stay of more than 5 days. Daily clinical and microbiological monitoring for secondary infection was undertaken until hospital discharge. In all, 59 selective decontamination and 76 placebo fully comparable patients fulfilled criteria for enrollment and analysis (APACHE II 15.2 vs 15.1). The number of patients receiving SDD who developed nosocomial infections was significantly reduced (P = 0.048), and there were no infections caused by the enterobacteriaceae or Candida spp in this group. No difference in ICU (17.5 vs 18.8 days) or hospital stay (32.7 vs 34.2 days) or mortality (17% vs 22.3%) was shown. Critically ill, primarily infected patients are protected from nosocomial infection by the use of SDD.