Ventilatory characteristics in mechanically ventilated patients during manual hyperventilation for chest physiotherapy

Changes in respiratory mechanics during respiratory physiotherapy in mechanically ventilated patients

Objective

To evaluate the changes in ventilatory mechanics and hemodynamics that occur in patients dependent on mechanical ventilation who are subjected to a standard respiratory therapy protocol.

Methods

This experimental and prospective study was performed in two intensive care units, in which patients dependent on mechanical ventilation for more than 48 hours were consecutively enrolled and subjected to an established respiratory physiotherapy protocol. Ventilatory variables (dynamic lung compliance, respiratory system resistance, tidal volume, peak inspiratory pressure, respiratory rate, and oxygen saturation) and hemodynamic variables (heart rate) were measured one hour before (T_-1), immediately after (T₀) and one hour after (T₊₁) applying the respiratory physiotherapy protocol.

Results

During the period of data collection, 104 patients were included in the study. Regarding the ventilatory variables, an increase in dynamic lung compliance (T_-1 = 52.3 ± 16.1mL/cmH₂O versus T₀ = 65.1 ± 19.1mL/cmH₂O; p < 0.001), tidal volume (T_-1 = 550 ± 134mL versus T₀ = 698 ± 155mL; p < 0.001), and peripheral oxygen saturation (T_-1 = 96.5 ± 2.29% versus T₀ = 98.2 ± 1.62%; p < 0.001) were observed, in addition to a reduction of respiratory system resistance (T_-1 = 14.2 ± 4.63cmH₂O/L/s versus T₀ = 11.0 ± 3.43cmH2O/L/s; p < 0.001), after applying the respiratory physiotherapy protocol. All changes were present in the assessment performed one hour (T₊₁) after the application of the respiratory physiotherapy protocol. Regarding the hemodynamic variables, an immediate increase in the heart rate after application of the protocol was observed, but that increase was not maintained (T_-1 = 88.9 ± 18.7 bpm versus T₀ = 93.7 ± 19.2bpm versus T₊₁ = 88.5 ± 17.1bpm; p < 0.001).

Conclusion

Respiratory therapy leads to immediate changes in the lung mechanics and hemodynamics of mechanical ventilation-dependent patients, and ventilatory changes are likely to remain for at least one hour.

Effect of Manual Hyperinflation on Hemodynamics, Gas Exchange, and Respiratory Mechanics in Ventilated Patients

The authors investigated the effect of manual hyperinflation (MHI) with set parameters applied to patients on mechanical ventilation on hemodynamics, respiratory mechanics, and gas exchange. Sixteen critically ill patients post-septic shock, with acute lung injury, were studied. Heart rate, arterial pressure, and mean pulmonary artery pressure were recorded every minute. Pulmonary artery occlusion pressure, cardiac output, arterial blood gases, and dynamic compliance (Cdyn) were recorded pre- and post-MHI. From this, systemic vascular resistance index (SVRI), cardiac index, oxygen delivery, and partial pressure of oxygen: fraction of inspired oxygen (PaO2:FiO2) ratio were calculated. There were significant increases in SVRI ( P < 0.05) post-MHI and diastolic arterial pressure ( P < 0.01) during MHI. Cdyn increased post-MHI ( P < 0.01) and was sustained at 20 minutes post-MHI ( P < 0.01). Subjects with an intrapulmonary cause of lung disease had a significant decrease ( P = 0.02) in PaO2:FiO2, and those with extrapulmonary causes of lung disease had a significant increase ( P < 0.001) in PaO2:FiO2 post-MHI. In critically ill patients, MHI resulted in an improvement in lung mechanics and an improvement in gas exchange in patients with lung disease due to extrapulmonary events and did not result in impairment of the cardiovascular system.

Manual hyperinflation combined with expiratory rib cage compression for reduction of length of ICU stay in critically ill patients on mechanical ventilation

OBJECTIVE

Although manual hyperinflation (MH) is widely used for pulmonary secretion clearance, there is no evidence to support its routine use in clinical practice. Our objective was to evaluate the effect that MH combined with expiratory rib cage compression (ERCC) has on the length of ICU stay and duration of mechanical ventilation (MV).

METHODS

This was a prospective randomized controlled clinical trial involving ICU patients on MV at a tertiary care teaching hospital between January of 2004 and January of 2005. Among the 49 patients who met the study criteria, 24 and 25 were randomly assigned to the respiratory physiotherapy (RP) and control groups, respectively. Of those same patients, 6 and 8, respectively, were later withdrawn from the study. During the 5-day observation period, the RP patients received MH combined with ERCC, whereas the control patients received standard nursing care.

RESULTS

The two groups were similar in terms of the baseline characteristics. The intervention had a positive effect on the duration of MV, as well as on the ICU discharge rate and Murray score. There were significant differences between the control and RP groups regarding the weaning success rate on days 2 (0.0% vs. 37.5%), 3 (0.0% vs. 37.5%), 4 (5.3% vs. 37.5%), and 5 (15.9% vs. 37.5%), as well as regarding the ICU discharge rate on days 3 (0% vs. 25%), 4 (0% vs. 31%), and 5 (0% vs. 31%). In the RP group, there was a significant improvement in the Murray score on day 5.

CONCLUSIONS

Our results show that the use of MH combined with ERCC for 5 days accelerated the weaning process and ICU discharge.

Physiotherapy in critically ill patients

Prolonged stay in Intensive Care Unit (ICU) can cause muscle weakness, physical deconditioning, recurrent symptoms, mood alterations and poor quality of life. Physiotherapy is probably the only treatment likely to increase in the short- and long-term care of the patients admitted to these units. Recovery of physical and respiratory functions, coming off mechanical ventilation, prevention of the effects of bed-rest and improvement in the health status are the clinical objectives of a physiotherapy program in medical and surgical areas. To manage these patients, integrated programs dealing with both whole-body physical therapy and pulmonary care are needed. There is still limited scientific evidence to support such a comprehensive approach to all critically ill patients; therefore we need randomised studies with solid clinical short- and long-term outcome measures.

Effect of chest wall vibration timing on peak expiratory flow and inspiratory pressure in a mechanically ventilated lung model

OBJECTIVE

To investigate the effects of chest wall vibration timing on air flow and pressure in a ventilated lung model.

DESIGN

Laboratory-based bench study.

PARTICIPANTS

Thirty physiotherapists with experience in intensive care.

INTERVENTION

Physiotherapists applied three sets of eight chest wall vibrations to an intubated, mechanically ventilated mannequin. Vibrations were applied at the start of expiration (optimal), mid to late inspiration (early) and early to mid expiration (late). Air flow, peak pressure and volume were measured continuously. Forces applied during vibrations were recorded using a force-sensing mat, placed under the physiotherapists' hands.

RESULTS

During optimal and early vibrations, peak expiratory flow increased significantly compared with baseline ventilation [mean difference for optimal vibrations 8.8l/minute, 95% confidence interval (CI) 6.0 to 11.6; mean difference for early vibrations 7.0l/minute, 95% CI 4.3 to 9.9]. Late vibrations did not enhance expiratory flow. Peak inspiratory pressure was significantly higher during early vibrations compared with baseline values (mean difference 5.6cmH(2)O, 95% CI 2.9 to 8.2). Peak inspiratory pressure generated during early vibrations was, on average, 8.4cmH(2)O greater than with optimal timing.

CONCLUSION

The safety and effectiveness of respiratory physiotherapy treatments are likely to be influenced by the timing of vibrations within the breath cycle. Early vibrations generate potentially dangerous peak inspiratory pressures. Late vibrations, although not harmful, are not effective at increasing peak expiratory flow. This is an important consideration when training physiotherapists and evaluating outcomes of treatments in intensive care.

Manual hyperinflation of intubated and mechanically ventilated patients in Dutch intensive care units--a survey into current practice and knowledge

BACKGROUND

In the daily bedside routine of the intensive care, potentially hazardous interventions that lack evidence need critical consideration. Therefore we examined current practice and knowledge of basic principles of manual hyperinflation (MH) in intubated and mechanically ventilated patients among intensive care unit nurses in the Netherlands.

METHODS

A written survey method was used, questionnaires were sent to ICU nurses specialised in mechanical ventilation in 115 Dutch hospitals. The questions related to following domains: (1) demographics; (2) use of MH; (3) presumed benefits; (4) essential elements of the MH procedure; (5) equipment and safety.

RESULTS

The response rate was 77%. From responding ICUs the majority (96%) stated they performed MH; 27% as a daily routine procedure, 69% performed MH on indication only. MH was mainly performed by ICU nurses. Half of ICUs reported to have a MH guideline available. Improved oxygenation and better removal of sputum were presumed benefits of MH. While slow inspiration and rapid expiration are considered to be essential elements of MH procedures, the majority of respondents stated to use rapid inspiration and slow expiration.

CONCLUSIONS

This survey indicates that MH is widely used as an important item of airway management. Importantly, there is no uniformity in the performance of the procedure. Before definitive research can be developed, standards for the MH procedure should be established.

Chest physiotherapy prolongs duration of ventilation in the critically ill ventilated for more than 48 hours

OBJECTIVE

This study aimed to determine the impact of providing chest physiotherapy after routine clinical assessment on the duration of mechanical ventilation, outcome and intensive care length of stay.

DESIGN AND SETTING

Single-centre, single-blind, prospective, randomised, controlled trial in a university hospital general intensive care unit.

PATIENTS AND PARTICIPANTS

180 patients requiring mechanical ventilation for more than 48 h.

INTERVENTIONS

Patients randomly allocated, one group receiving physiotherapy as deemed appropriate by physiotherapists after routine daily assessments and another group acting as controls were limited to receiving decubitus care and tracheal suctioning.

MEASUREMENTS AND RESULTS

Primary endpoints were initial time to become ventilator-free, secondary endpoints included intensive care unit (ICU) and hospital mortality and ICU length of stay. Kaplan-Meier analysis censored for death revealed a significant prolongation of median time to become ventilator-free among patients receiving physiotherapy (p=0.047). The time taken for 50% of patients (median time) to become ventilator-free was 15 and 11 days, respectively, for physiotherapy and control groups. There were no differences between groups in ICU or hospital mortality rates, or length of ICU stay. The number of patients needing re-ventilation for respiratory reasons was similar in both groups.

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 causes norepinephrine release

OBJECTIVE

To measure hemodynamics and plasma catecholamines during manual hyperinflation (MHI) in ventilated patients.

METHODS

MHI was performed with a Mapleson "C" circuit, 2l-reservoir bag; peak inspiratory pressure was standardized to 35 mL water; and positive expiratory-end pressure of 5 mL water was administered to seven mechanically ventilated patients with septic (6) and cardiogenic (1) shock (67.2 +/- 5.2 years, Acute Physiology Assessment and Chronic Health Evaluation II score 22.1 +/- 3.1). Diastolic (DAP) and mean arterial pressure (MAP), continuous cardiac index, pulmonary artery occlusion pressure, dynamic compliance, plasma norepinephrine and epinephrine, and arterial blood gases were recorded, and systemic vascular resistance index (SVRI) and oxygenation ratio were calculated.

RESULTS

There were no significant changes in pulmonary artery occlusion pressure, mean arterial pressure, or PaO2/FiO2. There were significant increases in SVRI (P < .001), DAP (P < .001), dynamic compliance (P < .01), and plasma norepinephrine (P < .001) and a decrease in cardiac index (P < .05) after MHI.

CONCLUSIONS

The increases in DAP, SVRI, and plasma norepinephrine suggest a sympathetic vasoconstrictive response during the application of MHI.

Effect of expiratory flow increase technique on pulmonary function of infants on mechanical ventilation

BACKGROUND AND PURPOSE

Although chest physiotherapy techniques are commonly used in the treatment of respiratory diseases, there are, however, few studies in the literature on the effectiveness of these techniques in paediatric patients. The purpose of the present study was to evaluate the effect of the expiratory flow increase technique (EFIT) on the pulmonary function of infants on invasive mechanical pulmonary ventilation.

METHOD

A prospective, non-randomized study design was used, with consecutive enrolment conducted in the paediatric intensive care unit (PICU) of a university hospital. All infants with acute obstructive respiratory failure who were on invasive mechanical pulmonary ventilation between April 2001 and April 2003 were included in this study. Respiratory rate, PaO2, PaCO2, SatO2, PaO2/FiO2, P(A-a)O2/PaO2, PaO2/PAO2, VD/VT, dynamic compliance, inspiratory and expiratory resistance values were compared before and after application of the EFIT.

RESULTS

Blood gas and pulmonary function measurements were recorded before and after EFIT. Repeated-measures analysis of variance (ANOVA) was used. The results were considered statistically significant when p values were < 0.05. Twenty-two infants were enrolled. There was a significant increase in respiratory rate, SatO2 and PaO2/PAO2 and a significant decrease in P(A-a)O2/PaO2 after application of the EFIT.

CONCLUSION

There was a short-term improvement in the oxygenation of infants who were submitted to the EFIT. Additional studies are necessary to establish the efficacy and effectiveness of this technique.

Early physiotherapy in the respiratory intensive care unit

Physiotherapy is an integral part of the management of patients in respiratory intensive care units (RICUs). The most important aim in this area is to enhance the overall patient's functional capacity and to restore his/her respiratory and physical independence, thus decreasing the risks of bed rest associated complications. This article is a review of evidence-based effectiveness of weaning practices and physiotherapy treatment for patients with respiratory insufficiency in a RICU. Literature searches were performed using general and specialty databases with appropriate keywords. The evidence for applying a weaning process and physiotherapy techniques in these patients has been described according to their individual rationale and efficacy. The growing number of patients treated in RICUs all over the world makes this non pharmacological approach both welcome and interesting. However, to date, there are only strong recommendations concerning the evidence-based strategies to speed weaning. Early physiotherapy may be effective in ICU: however, most techniques (postures, limb exercise and percussion/vibration in particular) need to be further studied in a large population. Evidence supporting physiotherapy intervention is limited as there are no studies examining the specific effects of interventions on long-term outcome.

The effect on expiratory flow rate of maintaining bag compression during manual hyperinflation

Operator performance during the expiratory phase of manual hyperinflation appears to vary between physiotherapists for Mapleson-B or C circuits. Some physiotherapists release the valve but maintain compression of the bag, whereas others release both the valve and the bag. The effect of this difference on peak expiratory flow rate (PEFR) has not been reported. The aim of this study was to document the effect of maintaining bag compression during expiration on PEFR and inspiratory to expiratory flow rate ratio (I:E). Six physiotherapists with experience using manual hyperinflation participated. A within-subjects repeated measures design was used. Subjects performed manual hyperinflation using a Mapleson-C circuit with 'rapid release', releasing the valve only, or releasing both the bag and the valve, during expiration in a test lung model. Inspiratory time was controlled using a metronome and flows were measured with a heated pneumotachometer. Maintaining bag compression significantly reduced PEFR (1.54 (0.08) vs 2.00 (0.07) l/sec, p = 0.008) and increased I:E flow rate ratio (0.65 (0.04) vs 0.50 (0.02), p = 0.02) for the Mapleson-C circuit at a 1.4 litre target volume. There were no significant differences for these measures between techniques when subjects emptied the bag. The effect needs to be confirmed in the clinical setting.

A comparison of the effects of manual and ventilator hyperinflation on static lung compliance and sputum production in intubated and ventilated intensive care patients

BACKGROUND AND PURPOSE

Lung hyperinflation is a technique used by physiotherapists to mobilize and remove excess bronchial secretions, reinflate areas of pulmonary collapse and improve oxygenation. Hyperinflation may be delivered by the ventilator or manually, by use of a manual resuscitation circuit, depending upon the respiratory and cardiovascular status of the patient. The effects of manual hyperinflation, with respect to excess bronchial secretions and static lung compliance, have been well-established. There is, however, only limited evidence as to the efficacy of ventilator hyperinflation as a physiotherapy treatment technique. The purpose of the present study was to compare the effects of manual hyperinflation and ventilator hyperinflation on static pulmonary compliance and sputum clearance in stable intubated and ventilated patients.

METHOD

Twenty patients who met the inclusion criteria were studied. This was a double crossover study where all patients were randomly allocated to one of two treatment sequences over two days. The first sequence involved manual hyperinflation followed two hours later by ventilator hyperinflation and the order was reversed on the second day. In the second sequence, ventilator hyperinflation preceded manual hyperinflation. The variables of static pulmonary compliance and sputum wet weight were analysed by use of an analysis of variance (ANOVA) for repeated measures. Statistical significance was set at p < 0.05.

RESULTS

There was no significant difference in sputum wet weight production between either technique or on either day of treatment. Static pulmonary compliance improved with both hyperinflation techniques (p < 0.05).

CONCLUSIONS

Hyperinflation as part of a physiotherapy treatment can be performed with equal benefit using either a manual resuscitation circuit or a ventilator. Both methods of hyperinflation improve static pulmonary compliance and clear similar volumes of pulmonary secretions.