Description of manual hyperinflation in intubated patients with atelectasis

Pattern of ventilation during manual hyperinflation performed by physiotherapists

Summary The aim of this prospective observational study was to document patterns of ventilation during manual hyperinflation by physiotherapists. Manual hyperinflation with a Mapleson-F system was performed on the same patients on two consecutive days. Patterns of ventilation were recorded using a heated pneumotachometer, pressure transducer and custom designed data acquisition and analysis systems. The mean (SE) results were: inspiratory time 1.45 (0.10) s; volume delivered 1.23 (0.07) l; peak inspiratory and expiratory flow rate 1.51 (0.06) l.s(-1) and 3.26 (0.30) l.s(-1), respectively and I : E flow rate ratio 0.63 (0.05). All the physiotherapists achieved an increase in volume which was delivered within a safe and effective pressure range and without cardiovascular compromise. Most (26 out of 34 sessions) performed the technique in the way recommended for enhancing secretion clearance. This is the first study to document comprehensively the pattern of ventilation during manual hyperinflation and provides the basis for further clinical trials evaluating its effectiveness for secretion clearance and volume restoration.

Manual hyperinflation improves alveolar recruitment in difficult-to-wean patients

STUDY OBJECTIVES

To investigate the effect of manual hyperinflation (MH) in patients with atelectasis associated with ventilation support.

DESIGN

Patients were randomized to either an experimental group or a control group.

SETTING

Pulmonary ICUs from two hospitals.

PATIENTS

Twenty-three patients with atelectasis associated with ventilation support.

INTERVENTIONS

The MH technique was at a rate of 8 to 13 breaths/min for a period of 20 min each session, three times per day for 5 days. The control group received their standard prescribed mechanical ventilation without supplemental MH. Sputum contents (wet/dry weight ratio, viscosity), respiratory system capacity (spontaneous tidal volume [Vt], maximal inspiratory pressure, rapid shallow breathing index [f/Vt], chest radiograph signs, and Pa(O2)/fraction of inspired oxygen [Fi(O2)]) were measured just prior to the MH at day 0 as baseline, and at day 3 and day 6 of the study.

MEASUREMENTS AND RESULTS

There were significant improvements in scores over the 6-day study in the experimental group compared to the control group in spontaneous Vt (p = 0.035) and chest radiograph signs (p = 0.040), and a trend toward improvement of f/Vt (p = 0.066) and Pa(O2)/Fi(O2) (p = 0.061) after adjustment for covariates. Other outcome variables did not differ significantly between the experimental and control groups.

CONCLUSIONS

MH performed on patients with atelectasis from ventilation support significantly improved alveolar recruitment.

Head-down tilt and manual hyperinflation enhance sputum clearance in patients who are intubated and ventilated

The purpose of this prospective randomised cross-over study was to measure peak expiratory flow rates during manual hyperinflation and to determine if the addition of a head-down tilt to physiotherapy treatment increased sputum production in patients who are intubated and ventilated. Twenty patients who were intubated, ventilated and haemodynamically stable were randomised to a sequence of physiotherapy treatment in a flat side-lying or a head-down tilt position. Peak expiratory flow rates were measured for each breath during manual hyperinflation using a Vitalograph peak flow meter. Sputum wet weight was collected for each treatment position and static pulmonary compliance was measured before and immediately following physiotherapy treatment. There was a significant increase in peak expiratory flow (p < 0.001) and sputum production (p = 0.008) in the head-down tilt position. The mean difference and 95% confidence intervals for expiratory flow were 0.17 (0.15 to 0.19) l/sec and for the wet weight of sputum 1.97 (0.84 to 3.10) g. The peak expiratory flow rate was sufficient to produce annular flow in both flat side-lying (1.97 +/- 0.09) l/sec and in the head-down tilt position (2.14 +/- 0.08) l/sec. Static pulmonary compliance improved significantly following physiotherapy treatment (p = 0.003). The mean difference and 95% confidence intervals pre- and post-treatment for static pulmonary compliance were 5.18 (2.14 to 8.22) ml/cmH(2)O. The results suggest that addition of a head-down tilt to physiotherapy treatment, including manual hyperinflation, in patients who are intubated and ventilated, increases sputum production and improves peak expiratory flow.

An evaluation of a single chest physiotherapy treatment on mechanically ventilated patients with acute lung injury

BACKGROUND AND PURPOSE

Acute lung injury is a lung pathology that presents frequently on the intensive care unit. Chest physiotherapy, in the form of endotracheal suction, alternate side-lying and manual hyperinflation, is usually given to patients with this condition with the intention of removing retained pulmonary secretions and recruiting collapsed distal lung units. Despite this common practice there is insufficient research on the effects of chest physiotherapy in patients with acute lung injury being ventilated mechanically. The aim of the present study was to further understanding of the effects of three modes of treatment in chest physiotherapy in an acute lung injury patient group.

METHOD

This randomized, controlled trial investigated all mechanically ventilated patients with acute lung injury admitted to the adult intensive care unit at Guy's and St Thomas' NHS Trust between August 1996 and July 1997, who matched the inclusion criteria. Patients were randomized into one of three treatment groups: Group 1 (suctioned only); Group 2 (positioned and suctioned); and Group 3 (positioned, manually hyperinflated and suctioned). Baseline and 10, 30 and 60 minutes' post-treatment data were recorded for dynamic pulmonary compliance, arterial blood gases and haemodynamic variables. Results were analysed by use of an SPSS software package with a repeated-measures analysis of variance (ANOVA).

RESULTS

Eighteen patients fitted the inclusion criteria. Significant changes were observed in both PaCO2 (p = 0.026) and dynamic compliance (p = 0.019) over time for all three groups. The arterial oxygen to fraction of inspired oxygen ratio (PaO2:FiO2) did not alter significantly in any of the groups. With respect to other oxygenation parameters, mixed venous oxygen saturation (SvO2) showed a significant difference between the groups. Heart rate (HR) and systemic blood pressure (BP) showed statistically significant, but not clinically significant differences over time.

CONCLUSIONS

Patients with acute lung injury are notably complex to nurse and may require protracted physiotherapy intervention, which may take many forms. As de-recruitment was the single most important event that occurred in the present study population, a prescriptive chest physiotherapy approach to treating mechanically ventilated patients with acute lung should be questioned and adapted accordingly.

Secretion movement during manual lung inflation and mechanical ventilation

This project aimed to investigate the direction of artificial sputum movement during mechanical ventilation (MV) and bagging (MH) using a tube model. Three solutions of artificial sputum (ultrasonic gel, viscosity 100, 200 and 300 poise (P)) were prepared. About 1 ml of gel was placed in a glass tube connected to a test lung at one end and, via a pneumotachograph, to either a mechanical ventilator or a self-inflating bag, at the other. The position of the gel in the tube was recorded before and after 20 artificial breaths. Simultaneous breath-to-breath respiratory mechanics were measured. The procedure was repeated three times for each gel viscosity, with a fresh experimental set up for each measurement. Results showed that the distance travelled from the lung was significantly greater with MH compared with MV (P < 0.001). The lower the gel viscosity, the further the gel moved from the lung with both ventilatory modes (P < 0.001). MH was superior to MV for secretion mobilisation in a tube model.

Manual hyperinflation: consistency and modification of the technique by physiotherapists

BACKGROUND AND PURPOSE

The present study aimed to evaluate the consistency with which physiotherapists apply manual hyperinflation to a test lung using the Air-Viva-2 or Mapleson-B resuscitation circuit, and their ability to modify the technique as pulmonary characteristics change.

METHOD

A quasi-experimental, randomized, repeated-measures design was used to study 16 volunteer physiotherapists performing manual hyperinflation to a test lung simulating three clinical situations. Each subject applied manual hyperinflation to the test lung for each simulation three times in one day using the resuscitation circuit that they would normally use in their clinical practice. Eight subjects used the Air-Viva-2 circuit and eight used the Mapleson-B circuit. Measurements of tidal volume (Vp), peak airway pressure (Paw) and fraction of delivered oxygen (FDO2) were recorded during each testing period. Inflation rate and minute volume were calculated.

RESULTS

As compliance decreased and airway resistance increased, VT decreased and Paw increased. Of the eight subjects using the Air-Viva-2 circuit, only three subjects delivered greater than 0.80 FDO2. All subjects using the Mapleson-B circuit delivered greater than 0.85 FDO2.

CONCLUSIONS

Subjects demonstrated good consistency in the application of manual hyperinflation for all three simulations and modified their technique appropriately as simulated pulmonary characteristics changed.

A survey of manual hyperinflation in Australian hospitals

A telephone survey was conducted to examine the use of manual hyperinflation (MHI) by physiotherapists in intensive care units (ICUs) in 32 Australian teaching hospitals. A 100 per cent response rate was obtained from senior ICU physiotherapists. Results showed that 91 per cent of respondents used manual hyperinflation as a physiotherapy treatment technique. There was strong agreement on the components of the technique, preferred treatment position, contraindications and perceived benefits but considerable variation in duration of treatment, number of breaths per set and circuits used. Fewer than 55 per cent stated that a maximum airways pressure of 40 cm H2O or less was used with MHI and only 31 per cent monitored airways pressure. These results are compared with previously published surveys.