[Follow-up and management of non-invasive home mechanical ventilation]

Beneficial effect of nocturnal oximetric control on the clinical and gasometric situation and the prognosis of patients with home non-invasive mechanical ventilation

INTRODUCTION AND OBJECTIVE

The effectiveness of home non-invasive mechanical ventilation (NIMV) is assessed by determining blood gas values in wakefulness, the evolution of their symptoms, and the monitoring of ventilation at night. The aim of our study is to evaluate whether defined values reached with outpatient monitoring by oximetry is related to the clinical, arterial gases and survival of a sample of patients with home NIMV.

MATERIAL AND METHOD

Retrospective observational cohort study of a series of patients receiving home NIMV treatment for different causes. Patients with amyotrophic lateral sclerosis and less than 3 months of follow-up were excluded. The evolution of the patient's symptoms, their baseline arterial blood gases in wakefulness, and home nocturnal oximetry records, are evaluated at each outpatient visit. Good maintained oximetry control (MOC) was defined when mean O2 saturation values were reached and maintained until the last revision. Patient groups were considered, according to whether or not a good MOC was achieved during follow-up.

RESULT

Four hundred patients were evaluated. Three hundred and sixty four (91%) were included in the study; their median age was 68 years, 51% were male. 37.6% had a good MOC during follow-up. Compared to patients with not good MOC, a better long-term mortality was obtained (16.8% vs 28.2%, P=.013), and an improvement in symptoms (33.8% vs 18.6%, P=.002) and a lower proportion of patients with persistently>50mmHg PaCO2 (14.2% vs. 33.9%, P<.001) was observed.

CONCLUSION

In the follow-up of patients with home NIMV in our context, values defined in home nocturnal oximetry (good MOC) are positively associated with clinical, gasometric and longer-term survival.

Nocturnal home pulse oximetry: variability and clinical implications in home mechanical ventilation

BACKGROUND

Nocturnal home pulse oximetry (NHPO) provides information by measuring a series of variables: time spent with SaO(2) <90% expressed as percentage (T90) or in minutes (Tm90), mean SaO(2) (MnS), and lowest SaO(2) (LwS.) The presence of significant nocturnal desaturation has been proposed as a parameter in decision making with regard to initiating home mechanical ventilation (HMV) or monitoring HMV effectiveness. However, there is limited information on the possible variability of the test, and this could influence the interpretation of results.

OBJECTIVES

To explore the variability between 2 consecutive measurements of NHPO and to determine clinical applications in HMV.

METHODS

The patients presented diseases susceptible to HMV treatment and were enrolled in stable condition without respiratory failure. NHPO was conducted on 2 consecutive nights. The variables analyzed were: T90, Tm90, Mns, and LwS. The coefficient of variation (CV), a concordance coefficient (CC), and the Bland-Altman method were used in order to explore the variability.

RESULTS

We studied 40 cases. Two were excluded, and the remaining 38 were aged 58 ± 16 years (19 males). Eighteen were receiving HMV. CV values exceeded 100% for T90 and Tm90 and were below 5% for MnS and LwS. The CC for T90, Tm90, and LwS showed confidence intervals with lower limits below 0.5, while for MnS the value was 0.88 (0.79-0.93).

CONCLUSIONS

There is a wide variability in NHPO recordings for T90, Tm90, and LwS, so a single determination to detect nocturnal desaturation may not be valid for decision making; the parameter with the least interindividual variability and intraindividual variability was MnS.