Bronchial asthma is one of the most common chronic illnesses in the world, with an incidence which varies between 1% and 18% depending on the country.1–3 According to information from this country, the incidence of asthma in adults oscillates between 1% and 5%, depending on the province.4

According to the World Health Organisation asthma causes 250 000 deaths every year.5 During the last decade, several different epidemiological studies showed that the mortality rate has levelled off or decreased in a number of countries.6,7

Asthma progresses with exacerbations which may: (i) develop slowly, in which case it is frequently associated with upper airway respiratory infections or difficulty in controlling the illness or (ii) develop quickly, in which case it is associated with inhaled allergens and the ingestion of drugs (AINE or beta-blockers), certain food-stuffs (due to additives and preservatives) or emotional stress; the latter are initially more serious (with a risk of intubation an death), but the response to treatment is better and faster. The intensity of the exacerbations is variable, in some cases progressing with light symptoms which may go unnoticed by the patient, and in others through a series of extremely serious episodes in which the patient's life may be in danger.8,9

Around 30% of the asthmatic exacerbations attended to in the emergency services of a hospital require hospitalisations.10,11 GINA (Global Initiative for Asthma) classifies the exacerbations as light, moderate, serious and almost fatal, depending on the patient's condition upon being examined.1 Incidence varies considerably depending on the definition used: between 49% and 16% for serious exacerbations and between 26% and 3% for almost fatal ones.10,12 Between 2% and 20% of all serious asthma exacerbations require intensive care, and between 10% and 63% present hypercapnia, while the need for tracheal intubation varies from 2% to 70%.13

Recently, a number of intermediate respiratory intensive care units (ICRUs) have emerged. These units make it possible for the patient to be monitored continuously and mechanical ventilation to be carried under the best possible conditions.14 To date no studies have been published to highlight the role that these units could play in the evolution and prognosis of patients with serious and acute deteriorations of their asthmatic condition.

The aim of the present study is to describe the characteristics and prognosis of asthmatic patients admitted to the ICRU of our centre with a primary diagnosis of acute asthmatic deterioration, as compared with the same number of patients admitted to the conventional hospital ward.

During the period of the study, 37 patients were admitted to the ICRU in our service with a primary diagnosis of deterioration of their asthmatic condition (which was 5.2% of the total number of patients in the ICRU) and 436 patients under conventional hospitalisation conditions with the same diagnosis. The characteristics of the subjects included, both the ICRU group and those hosptialised conventionally are shown in Table 1. When both groups are compared, no significant differences are found in relation to the patients and the illnesses they suffer from.

With reference to the ICRU, 10 patients were treating themselves at home with short-acting beta-2 adrenergic drugs, 22 patients were receiving treatment with inhaled cortisone, most of them in combination with long-action beta-2 adrenergic drugs, 4 patients were taking systemic cortisone and only 1 patient was not under any kind of treatment. Approximately half of the patients were being monitored regularly by a pulmonologist, and 55% had required one or more hospital admissions due to a deterioration of their bronchial asthmatic condition.

95% of the patients hospitalised in the unit had come from the emergency service, while the rest, 2 patients, had been transferred from the ICU. The most common causes of admission were severe respiratory insufficiency and hypercapnia, with the patients presenting a coefficient value for pressure arterial oxygen/fraction of inspired oxygen (PAFI) of 265±88 and 345±66, pressure arterial carbon dioxide of 48.5±19 and 43.2±7mmHg, and a peak-flow of 232±82 and 394±86l/min upon admission and discharge respectively.

The most frequent cause of exacerbation of the asthma was acute tracheobronchitis (62%) (Fig. 1). Thirteen patients presented fresh alveolar infiltrates in the thoracic X-ray, interpreted as pneumonia/atelectasis and one as cardiac insufficiency. The origin of these episodes was confirmed with sputum cultures in 24% of the cases, the following germs being the most frequent: Streptcoccus pneumoniae (2), Pseudomona aeruginosa (2), Staphylococcus aureus resistant to methicillin tracheostomy (2), Escherichia coli (2) and Klebsiella pneumoniae (1).

Fig. 1.

Causes of bronchial asthmatic exacerbation in ICRU (A) and in conventional hospitalisation (B).

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Ten patients required NIMV during an average of 5.8±4.7 days, and all of them presented associated pathologies such as obesity (n=5), kyphoscoliosis (n=3) or bronchiectasis (n=2). In 9 of the 10 cases, the reason for the NIMV was acute hypercapnic respiratory failure. The average stay in the unit was 5.5±4.5 days. Therapeutic failure occurred in 8% of the cases (defined as the need for tracheal intubation or exitus), 1 patient with asthma aggravated by pneumonia due to Legionella had to be transferred to the ICU and required intubation with mechanical ventilation and 2 patients, for whom aggressive manipulation would not have been appropriate, were exitus.

Six months after discharge, 6% of the patients died and 65% required readmission.

Upon comparison between the group admitted to the ICRU and the group hospitalised under conventional conditions, it was observed that the ICRU group had a tendency towards greater comorbidity, presented more cases of pneumonia as a cause of bronchial asthmatic exacerbation (13 vs 3, P>.05) and in the blood gases examination there was a lower pH content (7.37±0.11 vs 7.42±0.04, P<.05) and a higher pCO2 content (48.6±19.3 vs 40.4±6.8mmHg, P<.05). Besides the ICRU group, 10 other patients received NIMV treatment, while in the group from the conventional hospital ward only 1 did, which he had already been under treatment with at home. As regards the evolution of the condition during hospitalisation and 6 months after discharge, no differences were observed between the groups in terms of readmission or mortality. Table 2 shows the results of the variables recorded during hospitalisation for both groups.

A reduction was observed in the number of patients requiring admission to the ICU during the study due to deterioration of the bronchial asthma as the primary diagnosis (9 patients), compared with the same period of time (41 months) prior to the opening of the ICRU (19 patients).

The present study demonstrates that there is a group of asthmatic patients with greater comorbidity and more severe deteriorations of their bronchial asthmatic condition, frequently associated with respiratory acidosis, who benefit from treatment in an intermediate care unit. This benefit is based on the fact that the rate of admission to the ICU and a prognosis after 6 months is similar to deteriorations requiring admission to a conventional hospital ward, with a corresponding saving in health service costs, as, in the absence of these units, the patients in question would be admitted directly to the ICU.

Approximately 30% of the bronchial asthma deteriorations10 require hospitalisation, and up to 20% require ICU treatment.13Up to 40% of the patients in medical ICUs and 30% in surgical ICUs are admitted for the purpose of continuous monitoring, and not with a view to carrying out any specific therapeutic action.15 It has been observed that it is possible to reduce costs and improve the quality of ICUs in general by means of the use of ICRUs for patients coming out of an ICU, or for semi-critical patients or those whose condition is an intermediate degree of severity.15–17

To date there are two Spanish studies which have published data concerning a ICRU linked to a Pulmonology service collected during the course of one year. Sala et al. presented their data from the unit's activity obtained during the year 2006, with 206 admissions, 8 of which (3.9%) were due to asthmatic deteriorations.18 Similar results were obtained by the group at the Galdákano hospital, where out of a total of 212 admissions, 7 (3.3%) were due to acute asthmatic deterioration, 4 of whom required NIMV and 1 was exitus 90 days after discharge.19

The results of our study show that the asthmatic patients who are admitted to the ICRU are patients with greater comorbidity, a greater degree of hypercapnia and are shown in scans to be more severely affected than asthmatic patients admitted to the conventional hospital wards. Examinations of patients with severe deterioration have shown these factors to point to a negative prognosis.20,21 The microbiological profile encountered in these patients, with prevalence of Gram negatives and germs predominantly associated with hospital environments, confirms the greater severity characterising the condition of these patients.

Of the 37 patients admitted to our ICRU, 10 received NIMV treatment, of whom 2 died and 12 required admission to the ICU with tracheal intubation. The NIMV in the event of acute respiratory failure provides adequate ventilation support until the illness causing the deterioration improves or is dealt with by the appropriate medical treatment. In a number of different illnesses such as exacerbation of chronic obstructive pulmonary disease or acute lung edema, NIMV has been shown to be effective, as it reduces the need for tracheal intubation and mortality.22,23 The use of NIMV in asthmatic exacerbation is controversial. In 2009, a Cochrane review was published, the purpose of which was to determine the effectiveness of NIMV in the deterioration of asthma. It was only possible to include one clinical assay which demonstrated that the use of NIMV reduced the number of hospital admissions, increased the number of discharges from emergency services and improved the respiratory frequency and the parameters of lung function. But despite this its use remains controversial, which is the reason why more studies are needed.24Recently a review was published concerning the use of NIMV in asthmatic exacerbations. Despite the contradictory nature of certain studies with very small study populations, the authors conclude that, in an appropriate environment such as an ICU or ICRU, and with an experienced respiratory medical team, NIMV can be tried on certain patients.25 The rate of intubation and connection to a mechanical ventilator in severe asthmatic exacerbations varies between 2 and 60%.26–28

One of the aims of the ICRU is to reduce costs, by avoiding transfer to an ICU and encouraging rapid discharge from the latter.15–17 In the specific case of our hospital, in which the ICU bed incurs approximately double the cost of a ICRU bed, and is similar to that of a bed in a normal ward, our patients benefit from close monitoring without a corresponding increase in the cost of health care.

The present study has a series of limitations: (a) it is an observational study, which means that the results obtained cannot be used to establish causal relationships between the variables being studied, (b) it does not compare the results obtained in the ICRU with patients transferred to the ICU with the same characteristics, (c) the study sample is small, due to the clinical characteristics of the pathology being studied and (d) it did not take account of exposure to allergens as a cause of exacerbation.

In conclusion, this study provides information concerning patients with severe asthmatic exacerbations admitted to a ICRU linked to the Pulmonology Service which could be a useful alternative to admission to an ICU. Furthermore, it could serve to promote the development of other ICRUs in hospitals across the Spanish National Health Service.

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