Experimental study on the efficiency and safety of the manual hyperinflation maneuver as a secretion clearance technique

Manual and ventilator hyperinflation parameters used by intensive care physiotherapists in Sri Lanka: An online survey

INTRODUCTION

Hyperinflation is a common procedure to clear secretion, increase lung compliance and enhance oxygenation in mechanically ventilated patients. Hyperinflation can be provided as manual hyperinflation (MHI) or ventilator hyperinflation (VHI), where outcomes depend upon the methods of application. Hence it is crucial to assess the application of techniques employed in Sri Lanka due to observed variations from recommended practices.

OBJECTIVE

This study is aimed to evaluate the application and parameters used for MHI and VHI by physiotherapists in intensive care units (ICUs) in Sri Lanka.

METHODOLOGY

An online survey was conducted among physiotherapists who are working in ICUs in Sri Lanka using WhatsApp groups and other social media platforms.

RESULTS

A total of 96 physiotherapists responded. The survey comprised of three sections to obtain information about socio-demographic data, MHI practices and VHI practices. Most of the respondents (47%) worked in general hospitals and 74% of participants had a bachelor's degree in physiotherapy; 31.3% had 3-6 years of experience; 93.8% used hyperinflation, and 78.9% used MHI. MHI was performed routinely and as needed to treat low oxygen levels, abnormal breath sounds, and per physician orders while avoiding contraindications. Self-inflation bags are frequently used for MHI (40.6%). Only a few participants (26%) used a manometer or tracked PIP. In addition to the supine position, some participants (37.5%) used the side-lying position. Most physiotherapists followed the recommended MHI technique: slow squeeze (57.3%), inspiratory pause (45.8%), and quick release (70.8%). VHI was practised by 19.8%, with medical approval and it was frequently performed by medical staff compared to physiotherapists. Treatment time, number of breaths, and patient positioning varied, and parameters were not well-defined.

CONCLUSION

The study found that MHI was not applied with the recommended PIP, and VHI parameters were not identified. The study indicates a need to educate physiotherapists about current VHI and MHI practice guidelines.

PEEP-ZEEP Compared with Bag Squeezing and Chest Compression in Mechanically Ventilated Cardiac Patients: Randomized Crossover Clinical Trial

Background and Objectives: Perform the bag squeezing and PEEP-ZEEP techniques associated with manual chest compression in mechanically ventilated cardiac patients in order to observe their effectiveness in the removal of pulmonary secretions and safety from a hemodynamic and ventilatory point of view. Methods: This is a randomized crossover clinical trial developed in a hospital in southern Brazil. We included hemodynamically stable male and female patients aged over 18 years who used invasive mechanical ventilation for at least 48 h. The control group was established for the bag-squeezing technique and the intervention group for the PEEP-ZEEP maneuver, both associated with manual chest compression. Tracheal aspiration was performed 2 h before in order to match the groups in relation to the volume of secretion, and also immediately at the end of the techniques in order to measure the amount of secretion collected. Results: The sample had 36 individuals with a mean age of 70.3 years, 21% of the patients were male, and the majority (10.4%) were hospitalized for ischemic heart disease. DBP (p = 0.024), MAP (p = 0.004) and RR (p = 0.041) showed a significant difference in the post-moment in both groups. There was a significant difference in the reduction of peak pressure values (p = 0.011), in the moment after performing the techniques, and also in the Cdyn (p = 0.004) in the control group versus moment. Conclusions: Both maneuvers are safe in terms of hemodynamics and ventilatory mechanics, in addition to being capable of favoring airway clearance through secretion removal, and they can be used in routine physiotherapeutic care.

Manual hyperinflation in children

Manual hyperinflation is used in neonatal and pediatric intensive care units to promote expiratory flow bias, but there is no consensus on the benefits of the technique. Thus, a review that presents supporting evidence is necessary. This study aims to review the literature on the manual hyperinflation maneuver in neonatal and pediatric intensive care units to analyze the evidence for this technique in terms of the forms of application (associated with other techniques or not), its safety, the performance of manual resuscitators and the influence of the physical therapist's experience, in addition to evaluating the methodological quality of the identified articles. A search was performed in the following databases: Web of Science, ScienceDirect, PubMedⓇ, Scopus, CINAHL and SciELO. Two researchers independently selected the articles. Duplicate studies were assessed, evaluated by title and abstract and then read in full. The quality of the articles was analyzed using the PEDro scale. Six articles were included, two of which had high methodological quality. The main results provided information on the contribution of the positive end-expiratory pressure valve to increasing lung volumes and the use of chest compressions to optimize expiratory flow bias, the negative influence of operator experience on the increase in peak inspiratory flow, the performance of different manual resuscitators when used with the technique and the safety of application in terms of maintaining hemodynamic stability and increasing peripheral oxygen saturation. The available studies point to a positive effect of the manual hyperinflation maneuver in children who are admitted to intensive care units. Registration PROSPERO: CRD42018108056.

Acute effects of ventilator hyperinflation with increased inspiratory time on respiratory mechanics: randomized crossover clinical trial

Objective

To evaluate the effects of ventilator hyperinflation on respiratory mechanics.

Methods

A randomized crossover clinical trial was conducted with 38 mechanically ventilated patients with pulmonary infection. The order of the hyperinflation and control (without changes in the parameters) conditions was randomized. Hyperinflation was performed for 5 minutes in pressure-controlled ventilation mode, with progressive increases of 5cmH₂O until a maximum pressure of 35cmH₂O was reached, maintaining positive end expiratory pressure. After 35cmH₂O was reached, the inspiratory time and respiratory rate were adjusted so that the inspiratory and expiratory flows reached baseline levels. Measurements of static compliance, total resistance and airway resistance, and peak expiratory flow were evaluated before the technique, immediately after the technique and after aspiration. Two-way analysis of variance for repeated measures was used with Tukey's post hoc test, and p < 0.05 was considered significant.

Results

Ventilator hyperinflation increased static compliance, which remained at the same level after aspiration (46.2 ± 14.8 versus 52.0 ± 14.9 versus 52.3 ± 16.0mL/cmH₂O; p < 0.001). There was a transient increase in airway resistance (6.6 ± 3.6 versus 8.0 ± 5.5 versus 6.6 ± 3.5cmH₂O/Ls^-1; p < 0.001) and a transient reduction in peak expiratory flow (32.0 ± 16.0 versus 29.8 ± 14.8 versus 32.1 ± 15.3Lpm; p <0.05) immediately after the technique; these values returned to pretechnique levels after tracheal aspiration. There were no changes in the control condition, nor were hemodynamic alterations observed.

Conclusion

Ventilator hyperinflation promoted increased compliance associated with a transient increase in airway resistance and peak expiratory flow, with reduction after aspiration.

Impacts in the Respiratory Mechanics of the Ventilator Hyperinsuflation in the Flow Bias Concept: a Narrative Review

AbstractPatients who require invasive ventilatory support are subject to the deleterious effects of this, mainly ventilator-associated pneumonia (VAP). The physiotherapist, a member of the multiprofessional team, assists the patient with the purpose of promoting the recovery and preservation of the functionality, being able to minimize / avoid secondary complications. This study aims to identify the repercussions of mechanical ventilation hyperinflation (MVH) in the flow bias concept in respiratory mechanics. This study is a narrative review. MVH is an important resource commonly used in clinical practice that involves the manipulation of mechanical ventilator configurations to provide larger pulmonary volumes, and the generated airflow gradient may play a relevant role in mucus transport, with the concept of flow bias the main factor responsible for its direction. For the mobilization of the mucus towards the cephalic direction to occur, there must be a predominant expiratory flow, guaranteeing the peak ratio of expiratory flow / inspiratory flow peak (EFP / IFP) greater than 1.11. Maintenance of mechanical ventilation assures the patient to maintain the positive end expiratory pressure (PEEP) and the oxygen inspired fraction, avoiding the deleterious effects of the mechanical ventilator disconnection. MVH is able to improve lung compliance without, however, increasing airway resistance. MVH in the cephalic flow bias concept is effective for the mucus mobilization in the central direction, being able to improve pulmonary compliance and peripheral oxygen saturation.Keywords: Respiration, Artificial. Intensive Care Units. Physical Therapy Department, Hospital.ResumoOs pacientes internados que necessitam de suporte ventilatório invasivo estão sujeitos aos efeitos deletérios deste, principalmente a pneumonia associada à ventilação mecânica (PAV). O fisioterapeuta, integrante da equipe multiprofissional, assiste o paciente com a finalidade de promover a recuperação e preservação da funcionalidade, podendo minimizar/evitar complicações secundárias. Este estudo consiste em identificar as repercussões da hiperinsuflação com ventilador mecânico (HVM) no conceito flow bias na mecânica respiratória. O presente estudo trata-se de uma revisão narrativa. A HVM é um importante recurso comumente utilizado na prática clínica que envolve a manipulação das configurações do ventilador mecânico para fornecer maiores volumes pulmonares, e o gradiente de fluxo de ar gerado pode desempenhar um papel relevante no transporte do muco, sendo o conceito de flow bias cefálico o principal fator responsável pelo direcionamento deste. Para que a mobilização do muco em direção cefálica ocorra, deve existir um fluxo expiratório predominante, garantindo a razão pico de fluxo expiratório/pico de fluxo inspiratório (PFE/PFI) maior do que 1,11. A manutenção da assistência ventilatória mecânica assegura ao paciente a manutenção da pressão positiva ao final da expiração (PEEP) e a fração inspirada de oxigênio (FiO2), evitando os efeitos deletérios da desconexão do ventilador mecânico. A HVM é capaz de melhorar a complacência pulmonar sem, no entanto, aumentar a resistência das vias aéreas. A HVM no conceito flow bias cefálico é eficaz para a mobilização do muco em direção central, sendo capaz de melhorar a complacência pulmonar e saturação periférica de oxigênio (SpO2).Palavras-chave: Respiração Artificial. Unidades de Terapia Intensiva. Serviço Hospitalar de Fisioterapia.

Effects of ventilation mode and manual chest compression on flow bias during the positive end- and zero end-expiratory pressure manoeuvre in mechanically ventilated patients: a randomised crossover trial

OBJECTIVES

To investigate the effects of ventilation mode and manual chest compression (MCC) application on the flow bias generated during positive end-expiratory pressure-zero end-expiratory pressure (PEEP-ZEEP) in mechanically ventilated patients. PEEP-ZEEP is an airway clearance manoeuvre with the potential to exceed the flow bias required to remove secretions. However, the ventilation mode applied during the manoeuvre has not been standardised.

DESIGN

Randomised crossover trial.

PARTICIPANTS

Nineteen mechanically ventilated patients.

INTERVENTIONS

Patients were randomised to receive PEEP-ZEEP in volume-controlled and pressure-controlled modes, and with or without MCC.

MAIN OUTCOME MEASURES

The difference in flow bias - assessed by the peak expiratory flow (PEF) and peak inspiratory flow (PIF) ratio and difference - between PEEP-ZEEP applied in both ventilation modes, and with and without MCC.

RESULTS

The expiratory flow bias was significantly higher in the volume-controlled mode than the pressure-controlled mode. This result was caused by a lower PIF in the volume-controlled mode. PEEP-ZEEP applied in the pressure-controlled mode did not achieve the PEF-PIF difference threshold to clear mucus. Moreover, in the majority of cycles of PEEP-ZEEP applied in the pressure-controlled mode, an inspiratory flow bias was generated, which might embed mucus. PEF was 8l/minute higher with MCC compared with without MCC, which increased the PEF-PIF difference by the same amount. No haemodynamic or respiratory adverse effects were found.

CONCLUSIONS

If applied in the volume-controlled mode, PEEP-ZEEP can achieve the flow bias needed to expel pulmonary secretions. However, this is not the case in the pressure-controlled mode. MCC can augment the flow bias generated by PEEP-ZEEP, but its application may be dispensable.

CLINICAL TRIAL REGISTRATION

http://www.ensaiosclinicos.gov.br/rg/RBR-223xv8/.

Effects of manual hyperinflation, clinical practice versus expert recommendation, on displacement of mucus simulant: A laboratory study

Introduction

Manual hyperinflation (MH), a maneuver applied in mechanically ventilated patients to facilitate secretion removal, has large variation in its performance. Effectiveness of MH is usually evaluated by its capacity to generate an expiratory flow bias. The aim of this study was to compare the effects of MH—and its resulting flow bias—applied according to clinical practice versus according to expert recommendation on mucus movement in a lung model simulating a mechanically ventilated patient.

Methods

Twelve physiotherapists were asked to apply MH, using a self-inflating manual resuscitator, to a test lung as if to remove secretions under two conditions: according to their usual clinical practice (pre-instruction phase) and after verbal instruction to perform MH according to expert recommendation was given (post-instruction phase). Mucus simulant movement was measured with a photodensitometric technique. Peak inspiratory flow (PIF), peak inspiratory pressure (P_IP), inspiratory time (T_INSP), tidal volume (V_T) and peak expiratory flow (PEF) were measured continuously.

Results

It was found that MH performed post-instruction delivered a smaller V_T (643.1 ± 57.8 ml) at a lower P_IP (15.0 ± 1.5 cmH₂O), lower PIF (38.0 ± 9.6 L/min), longer T_INSP (1.84 ±0.54 s) and lower PEF (65.4 ± 6.7L/min) compared to MH pre-instruction. In the pre-instruction phase, MH resulted in a mean PIF/PEF ratio of 1.73 ± 0.38 and mean PEF-PIF difference of -54.6 ± 28.3 L/min, both out of the range for secretion removal. In the post-instruction phase both indexes were in the adequate range. Consequently, the mucus simulant was moved outward when MH was applied according to expert recommendation and towards the test lung when it was applied according to clinical practice.

Conclusions

Performance of MH during clinical practice with PIF higher than PEF was ineffective to clear secretion in a lung model simulating a mechanically ventilated patient. In order to remove secretion, MH should result in an adequate expiratory flow bias.

Manual hyperinflation and the role of physical therapy in intensive care and emergency units

Abstract Introduction: Although manual hyperinflation (MHI) is a physical therapy technique commonly used in intensive care and emergency units, there is little consensus about its use. Objective: To investigate the knowledge of physical therapists working in intensive care and emergency units about manual hyperinflation. Methods: Data were collected through self-administered questionnaires on manual hyperinflation. Data collection took place between September 2014 and January 2015, in Itabuna and Ilhéus, Bahia, Brazil. Results: The study sample was composed of 32 physical therapists who had between 4 months and 10 years working experience. All respondents affirmed that they used the technique in their professional practice. However, only 34.4% reported it to be a routine practice. 90.6% stated that the most common patient position during manual hyperinflation is “supine”. Participants were almost unanimous (93.8%) in citing secretion removal and cough stimulation as perceived benefits of MHI. High peak airway pressure was identified as being a precaution to treatment with MHI by 84.4% of participants, whilst 100% of the sample agreed that an undrained pneumothorax was a contraindication to MHI. Conclusion: The most common answers to the questionnaire were: supine position during MHI; secretion removal and cough stimulation as perceived benefits; high peak airway pressure as a precaution; and an undrained pneumothorax as a contraindication.

Effects of manual hyperinflation in preterm newborns under mechanical ventilation

Objective

To assess the effects of manual hyperinflation, performed with a manual resuscitator with and without the positive end-expiratory pressure valve, on the respiratory function of preterm newborns under mechanical ventilation.

Methods

Cross-sectional study of hemodynamically stable preterm newborns with gestational age of less than 32 weeks, under mechanical ventilation and dependent on it at 28 days of life. Manual hyperinflation was applied randomly, alternating the use or not of the positive end-expiratory pressure valve, followed by tracheal aspiration for ending the maneuver. For nominal data, the two-tailed Wilcoxon test was applied at the 5% significance level and 80% power.

Results

Twenty-eight preterm newborns, with an average birth weight of 1,005.71 ± 372.16g, an average gestational age of 28.90 ± 1.79 weeks, an average corrected age of 33.26 ± 1.78 weeks, and an average mechanical ventilation time of 29.5 (15 - 53) days, were studied. Increases in inspiratory and expiratory volumes occurred between time-points A5 (before the maneuver) and C1 (immediately after tracheal aspiration) in both the maneuver with the valve (p = 0.001 and p = 0.009) and without the valve (p = 0.026 and p = 0.001), respectively. There was also an increase in expiratory resistance between time-points A5 and C1 (p = 0.044).

Conclusion

Lung volumes increased when performing the maneuver with and without the valve, with a significant difference in the first minute after aspiration. There was a significant difference in expiratory resistance between the time-points A5 (before the maneuver) and C1 (immediately after tracheal aspiration) in the first minute after aspiration within each maneuver.

Lung hyperinflation by mechanical ventilation versus isolated tracheal aspiration in the bronchial hygiene of patients undergoing mechanical ventilation

OBJECTIVE

To determine the efficacy of lung hyperinflation maneuvers via a mechanical ventilator compared to isolated tracheal aspiration for removing secretions, normalizing hemodynamics and improving lung mechanics in patients on mechanical ventilation.

METHODS

This was a randomized crossover clinical trial including patients admitted to the intensive care unit and on mechanical ventilation for more than 48 hours. Patients were randomized to receive either isolated tracheal aspiration (Control Group) or lung hyperinflation by mechanical ventilator (MVH Group). Hemodynamic and mechanical respiratory parameters were measured along with the amount of aspirated secretions.

RESULTS

A total of 50 patients were included. The mean age of the patients was 44.7 ± 21.6 years, and 31 were male. Compared to the Control Group, the MVH Group showed greater aspirated secretion amount (3.9g versus 6.4g, p = 0.0001), variation in mean dynamic compliance (-1.3 ± 2.3 versus -2.9 ± 2.3; p = 0.008), and expired tidal volume (-0.7 ± 0.0 versus -54.1 ± 38.8, p = 0.0001) as well as a significant decrease in peak inspiratory pressure (0.2 ± 0.1 versus 2.5 ± 0.1; p = 0.001).

CONCLUSION

In the studied sample, the MVH technique led to a greater amount of aspirated secretions, significant increases in dynamic compliance and expired tidal volume and a significant reduction in peak inspiratory pressure.

Effect of Inspiratory Time and Lung Compliance on Flow Bias Generated During Manual Hyperinflation: A Bench Study

BACKGROUND

Manual hyperinflation can be used to assist mucus clearance in intubated patients. The technique's effectiveness to move mucus is underpinned by its ability to generate flow bias in the direction of expiration, and this must exceed specific thresholds. It is unclear whether the inspiratory times commonly used by physiotherapists generate sufficient expiratory flow bias based on previously published thresholds and whether factors such as lung compliance affect this.

METHODS

In a series of laboratory experiments, we applied manual hyperinflation to a bench model to examine the role of 3 target inspiratory times and 2 lung compliance settings on 3 measures of expiratory flow bias.

RESULTS

Longer inspiratory times and lower lung compliances were associated with improvements in all measures of expiratory flow bias. In normal compliance lungs, achievement of the expiratory flow bias thresholds were (1) never achieved with an inspiratory time of 1 s, (2) rarely achieved with an inspiratory time of 2 s, and (3) commonly achieved with an inspiratory time of 3 s. In lower compliance lungs, achievement of the expiratory flow bias thresholds was (1) rarely achieved with an inspiratory time of 1 s, (2) sometimes achieved with an inspiratory time of 2 s, and (3) nearly always achieved with an inspiratory time of 3 s. Peak inspiratory pressures exceeded 40 cm H2O in normal compliance lungs with inspiratory times of 1 s and in lower compliance lungs with inspiratory times of 1 and 2 s.

CONCLUSIONS

Inspiratory times of at least 3 s with normal compliance lungs and at least 2 s with lower compliance lungs appear necessary to achieve expiratory flow bias thresholds during manual hyperinflation. Inspiratory times shorter than this may lead to excessive peak inspiratory pressures. Verification of these findings in relation to the movement of mucus should be examined in further bench or animal models and/or human clinical trials.

Chest compression with a higher level of pressure support ventilation: effects on secretion removal, hemodynamics, and respiratory mechanics in patients on mechanical ventilation

OBJECTIVE

To determine the efficacy of chest compression accompanied by a 10-cmH2O increase in baseline inspiratory pressure on pressure support ventilation, in comparison with that of aspiration alone, in removing secretions, normalizing hemodynamics, and improving respiratory mechanics in patients on mechanical ventilation.

METHODS

This was a randomized crossover clinical trial involving patients on mechanical ventilation for more than 48 h in the ICU of the Porto Alegre Hospital de Clínicas, in the city of Porto Alegre, Brazil. Patients were randomized to receive aspiration alone (control group) or compression accompanied by a 10-cmH2O increase in baseline inspiratory pressure on pressure support ventilation (intervention group). We measured hemodynamic parameters, respiratory mechanics parameters, and the amount of secretions collected.

RESULTS

We included 34 patients. The mean age was 64.2 ± 14.6 years. In comparison with the control group, the intervention group showed a higher median amount of secretions collected (1.9 g vs. 2.3 g; p = 0.004), a greater increase in mean expiratory tidal volume (16 ± 69 mL vs. 56 ± 69 mL; p = 0.018), and a greater increase in mean dynamic compliance (0.1 ± 4.9 cmH2O vs. 2.8 ± 4.5 cmH2O; p = 0.005).

CONCLUSIONS

In this sample, chest compression accompanied by an increase in pressure support significantly increased the amount of secretions removed, the expiratory tidal volume, and dynamic compliance. (ClinicalTrials.gov Identifier:NCT01155648 [http://www.clinicaltrials.gov/]).