Comparison of flow rates produced by two frequently used manual hyperinflation circuits: a benchtop study

Ventilator hyperinflation - what settings generate an expiratory flow rate bias?

OBJECTIVES

To determine which mechanical ventilation settings influence the attainment of expiratory flow rate characteristics that may promote secretion mobilisation during ventilator hyperinflation (VHI).

DESIGN

Prospective, single centre study.

SETTING

Intensive care unit, tertiary metropolitan hospital.

PARTICIPANTS

Twenty-four patients receiving mechanical ventilation.

INTERVENTIONS

Patients were recruited to either a low PEEP or high PEEP group (5-9 cmH₂O or 10-15 cmH₂O PEEP respectively). Each group had three hyperinflation protocols applied.

MAIN OUTCOME MEASURES

Peak inspiratory flow rates (PIFR) and peak expiratory flow rates (PEFR) were measured and reported as PIFR/PEFR of less than or equal to 0.9; a PEFR-PIFR greater than or equal to 33 L/min; and PEFR greater than or equal to 40 L/min.

RESULTS

In both the low and high PEEP groups, VHI protocols using volume-controlled ventilation were significantly better at generating expiratory flow rate bias compared to pressure-controlled or Pressure Support ventilation. An expiratory flow rate bias was also achieved when VHI was performed in volume-controlled ventilation with either a peak inspiratory pressure target of 35 cmH₂O or a driving pressure of 20 cmH₂O. Median heart rate and blood pressure values did not change during VHI, but transient reductions in blood pressure were present in six participants (25%).

CONCLUSIONS

VHI performed using volume-controlled ventilation was more effective than pressure-controlled or Pressure Support ventilation to generate an expiratory flow rate bias.

CONTRIBUTION OF THE PAPER

Mechanical ventilator settings can be altered to perform hyperinflation and achieve expiratory flow rate properties that may increase the mobilisation of airway secretions. The results demonstrate that to achieve these properties.

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.

[Physiotherapy interventions in the ICU : Outcome-relevant measurement parameters]

BACKGROUND

Guidelines cannot provide differentiated recommendations for physiotherapy (PT) in intensive care medicine. Scientific publications for PT in the intensive care unit (ICU) usually only have low levels of evidence and often express safety and feasibility of PT in the ICU.

OBJECTIVE

Which measurement parameters are relevant for defining outcome and what interventions should one take into consideration?

MATERIALS AND METHODS

A literature review was conducted. This was based on a PubMed search with full text access, as well as specific definitions for physical therapy, intensive care and four out of seven conditions from the manual "Physiotherapy in intensive care".

RESULTS

The availability of 172 studies clearly shows that there is certainly PT research concerning the critical environment of the ICU. However, parameters for quantitative and qualitative detection of vigilance and state of consciousness as well as assessments to evaluate the mobility and the ability to help themselves are important for everyday use.

CONCLUSIONS

The difficulties of using PT in the ICU are not useful in ensuring the safety of the patient or performing a PT treatment. The conditions of the intensive care environment are not an obstacle. It is of immanent importance to use the limited resources of PT in an optimal and targeted manner in the ICU environment. The determination of ICU-adapted goals plays a crucial role.

Manual hyperinflation in airway clearance in pediatric patients: a systematic review

Objective

To perform an assessment of the available literature on manual hyperinflation as a respiratory physical therapy technique used in pediatric patients, with the main outcome of achieving airway clearance.

Methods

We reviewed articles included in the Lilacs (Latin American and Caribbean Literature on Health Sciences/Literatura Latino Americana e do Caribe em Ciências da Saúde), Cochrane Library, Medline (via Virtual Health Library and PubMed), SciELO (Scientific Electronic Library), and PEDro (Physiotherapy Evidence Database) databases from 2002 to 2013 using the following search terms: "physiotherapy (techniques)", "respiratory therapy", "intensive care", and "airway clearance". The selected studies were classified according to the level of evidence and grades of recommendation (method of the Oxford Centre for Evidence-Based Medicine) by two examiners, while a third examiner repeated the search and analysis and checked the classification of the articles.

Results

Three articles were included for analysis, comprising 250 children (aged 0 to 16 years). The main diagnoses were acute respiratory failure, recovery following heart congenital disease and upper abdominal surgery, bone marrow transplantation, asthma, tracheal reconstruction, brain injury, airway injury, and heterogeneous lung diseases. The studies were classified as having a level of evidence 2C and grade of recommendation C.

Conclusions

Manual hyperinflation appeared useful for airway clearance in the investigated population, although the evidence available in the literature remains insufficient. Therefore, controlled randomized studies are needed to establish the safety and efficacy of manual hyperinflation in pediatric patients. However, manual hyperinflation must be performed by trained physical therapists only.

Guideline implementation powered by feedback and education improves manual hyperinflation performance

AIM

To determine whether a literature-based guideline, powered by educational meetings and individual feedback, improves manual hyperinflation (MH) performance by intensive care unit (ICU) nurses.

BACKGROUND

MH is frequently applied in intubated and mechanically ventilated ICU patients. MH is a complex intervention, and large variation in its performance has been found.

MATERIALS AND METHODS

First, a literature-based guideline on MH was developed. The intervention consisted of education of this guideline and individual feedback. Before and 3 months after the intervention, ICU nurses performed MH maneuvers in a skills laboratory. Data collected included applied volumes, peak inspiratory flows (PIF) and peak expiratory flows (PEF), and the use of inspiratory holds.

RESULTS

Eighty nurses participated. Decrease of PIF was not statistically significant. PEF increased from 52 ± 7 to 83 ± 23 L/min (P < 0·01). PIF to PEF ratio decreased from 1·4 [1·1-1·7] to 0·8 [0·6-1·1] (P < 0·01). Peak inspiratory pressures decreased from 40 ± 14 to 19 ± 6 cm H2 O (P < 0·01). The proportion of nurses applying inspiratory holds increased from 14% to 58%; use of rapid release of the resuscitation bag, considered mandatory, increased from 4% to 61%.

CONCLUSION

Implementation of a literature-based guideline on MH, powered by educational meetings and individual feedback, improves MH performance by ICU nurses.

RELEVANCE TO CLINICAL PRACTICE

If it is decided to practice MH in the care of the intubated and mechanical ventilated patient, a standardized, uniform performed MH procedure is a prerequisite.

Hiperinsuflação manual: revisão de evidências técnicas e clínicas

INTRODUÇÃO: A técnica de hiperinsuflação manual (HM), também conhecida como "bag squeezing" ou "bagging", foi inicialmente descrita como um recurso para melhorar a oxigenação pré e pós-aspiração traqueal, mobilizar o excesso de secreção brônquica e reexpandir áreas pulmonares colapsadas. OBJETIVO: Apresentar evidências científicas sobre os efeitos da manobra de HM como recurso fisioterapêutico, bem como suas indicações clínicas. MATERIAIS E MÉTODOS: Realizou-se uma busca nas bases de dados eletrônicas SciELO, ScienceDirect, PubMed e PEDro, utilizando-se os descritores "hiperinsuflação manual" (manual hyperinflation) e "fisioterapia" (physiotherapy). Como critério de inclusão considerou-se: conter os descritores no título ou resumo; ensaios clínicos que abordassem "hiperinsuflação manual" e fisioterapia; textos em inglês e português; publicações entre 1994 e 2011. RESULTADOS: Foram selecionados 25 estudos e todos apontaram a importância dessa manobra na mobilização de secreções traqueobrônquicas e para reexpansão de alvéolos colapsados, devido à melhora do volume pulmonar. Adequação das trocas gasosas, melhora da oxigenação e da complacência pulmonar, prevenção e tratamento de atelectasias são outras indicações. Também é consensual a preocupação com a padronização na aplicação da técnica. Melhores resultados são alcançados quando o volume aplicado é cerca de 50% maior que o volume corrente do paciente. Precauções quanto a limites de pressão em torno de 40 cm H2O, para se evitar barotraumas, também são referidas pela maioria dos estudos. CONCLUSÃO: A literatura traz evidências que sustentam a indicação do HM para mobilização e eliminação de secreções traqueobrônquicas e prevenção de infecções/complicações, além da necessidade de padronização da técnica.

Airflow distribution with manual hyperinflation as assessed through gamma camera imaging: a crossover randomised trial

OBJECTIVES

Manual hyperinflation (MHI) has been shown to improve lung compliance, reduce airway resistance, and enhance secretion removal and peak expiratory flow. The aims of this study were to investigate whether there is a difference in airflow distribution through patients' lungs when using the Laerdal and Mapleson-C circuits at a set level of positive end-expiratory pressure (PEEP), and to establish whether differences in lung compliance and haemodynamic status exist when patients are treated with both these MHI circuits.

DESIGN

Crossover randomised controlled trial.

SETTING

Adult multidisciplinary intensive care unit (ICU) at an academic hospital.

PARTICIPANTS

Fifteen adult patients were recruited and served as their own controls.

INTERVENTION

In the Nuclear Medicine Department, MHI with PEEP 7.5 cmH(2)O was performed in the supine position (Day 1) with either Laerdal or Mapleson-C circuits, in a random order, while technetium-99m (Tc-99m) aerosol was administered and images were taken with a gamma camera. Changes in heart rate (HR), mean arterial pressure (MAP) and dynamic lung compliance (C(D)) were documented at baseline, immediately after return to ICU, and 10, 20 and 30 minutes after return to ICU. The alternative circuit was used on Day 2.

RESULTS

Tc-99m deposition was greater in the right lung field (62% and 63% for Laerdal and Mapleson-C circuits, respectively) than the left lung field (38% and 37%, respectively) for all patients, and least deposition occurred in the left lower segments (6% and 6%, respectively). No differences in Tc-99m deposition in the lungs, HR, MAP or C(D) were noted between the two MHI circuits.

CONCLUSION

Airflow distribution through patients' lungs was similar when the Laerdal and Mapleson-C MHI circuits were compared using a set level of PEEP in the supine position.

Chest associated to motor physiotherapy improves cardiovascular variables in newborns with respiratory distress syndrome

BACKGROUND

We aimed to evaluate the effects of chest and motor physiotherapy treatment on hemodynamic variables in preterm newborns with respiratory distress syndrome.

METHODS

We evaluated heart rate (HR), respiratory rate (RR), systolic (SAP), mean (MAP) and diastolic arterial pressure (DAP), temperature and oxygen saturation (SO2%) in 44 newborns with respiratory distress syndrome. We compared all variables between before physiotherapy treatment vs. after the last physiotherapy treatment. Newborns were treated during 11 days. Variables were measured 2 minutes before and 5 minutes after each physiotherapy treatment. We applied paired Student t test to compare variables between the two periods.

RESULTS

HR (148.5 ± 8.5 bpm vs. 137.1 ± 6.8 bpm - p < 0.001), SAP (72.3 ± 11.3 mmHg vs. 63.6 ± 6.7 mmHg - p = 0.001) and MAP (57.5 ± 12 mmHg vs. 47.7 ± 5.8 mmHg - p = 0.001) were significantly reduced after 11 days of physiotherapy treatment compared to before the first session. There were no significant changes regarding RR, temperature, DAP and SO2%.

CONCLUSIONS

Chest and motor physiotherapy improved cardiovascular parameters in respiratory distress syndrome newborns.