Cardiorespiratory effects of manually compressing the rib cage during tidal expiration in mechanically ventilated patients recovering from acute severe asthma

Manual external chest compression reverses respiratory failure in children with severe air trapping

We report manual external chest compression (MECC) as an effective treatment for acute respiratory failure due to severe air trapping. In this retrospective study, we describe our experience with MECC administered to five children suffering from severe air trapping as a consequence of severe asthma or bronchiolitis. These children were admitted to the Pediatric Intensive Care Unit (PICU) with clinical and blood gases parameters compatible with acute respiratory failure. Before intubation MECC was performed. The results of blood gasses before, during, and after MECC showed gradual changes in PCO₂ over time indicating the improvement in tidal volume and ventilation. Respiratory failure resolved in all five children within 4 h with no complications. The need for intubation and mechanical ventilation was avoided, and all children were discharged from the PICU within 48 h.

Effects of manual rib cage compressions on expiratory flow and mucus clearance during mechanical ventilation

OBJECTIVES

We investigated the effects of two different types of manual rib cage compression on expiratory flow and mucus clearance during prolonged mechanical ventilation in pigs.

DESIGN

Prospective randomized animal study.

SETTING

Animal research facility, University of Barcelona, Spain.

SUBJECTS

Nine healthy pigs.

MEASUREMENT AND MAIN RESULTS

Pigs were tracheally intubated, sedated, paralyzed, and mechanically ventilated. The animals were prone on a surgical bed in the anti-Trendelenburg position. The experiments were carried out at approximately 60 and 80 hrs from the beginning of mechanical ventilation. Two types of manual rib cage compressions were tested: Hard and brief rib cage compressions synchronized with early expiratory phase (hard manual rib cage compression) and soft and gradual rib cage compressions applied during the late expiratory phase (soft manual rib cage compression). The interventions were randomly applied for 15min with a 15-min interval between treatments. Respiratory flow and mucus movement were assessed during the interventions. Respiratory mechanics and hemodynamics were assessed prior to and after the interventions. Peak expiratory flow increased to 60.1±7.1L/min in comparison to 51.2±4.6L/min without treatment (p < 0.0015) and 48.7±4.3L/min with soft manual rib cage compression (p = 0.0002). Similarly, mean expiratory flow increased to 28.4±5.2L/min during hard manual rib cage compression vs. 15.9±2.2 and 16.6±2.8L/min without treatment and soft manual rib cage compression, respectively (p = 0.0006). During hard manual rib cage compression, mucus moved toward the glottis (1.01 ± 2.37mm/min); conversely, mucus moved toward the lungs during no treatment and soft manual rib cage compression, -0.28 ± 0.61 and -0.15±0.95mm/min, respectively (p = 0.0283). Soft manual rib cage compression slightly worsened static lung elastance and cardiac output (p = 0.0391).

CONCLUSIONS

Hard manual rib cage compression improved mucus clearance in animals positioned in the anti-Trendelenburg position. The technique appeared to be safe. Conversely, soft manual rib cage compression was not effective and potentially unsafe. These findings corroborate the predominant role of peak expiratory flow on mucus clearance.

[Effects of manually assisted coughing on respiratory mechanics in patients requiring full ventilatory support]

OBJECTIVE

Manually assisted coughing (MAC) consists of a vigorous thrust applied to the chest at the beginning of a spontaneous expiration or of the expiratory phase of mechanical ventilation. Due to routine use of MAC in intensive care units, the objective of this study was to assess the effects of MAC on respiratory system mechanics in patients requiring full ventilatory support.

METHODS

We assessed 16 sedated patients on full ventilatory support (no active participation in ventilation). Respiratory system mechanics and oxyhemoglobin saturation were measured before and after MAC, as well as after endotracheal aspiration. Bilateral MAC was performed ten times on each patient, with three respiratory cycle intervals between each application.

RESULTS

Data analysis demonstrated a decrease in resistive pressure and respiratory system resistance, together with an increase in oxyhemoglobin saturation, after MAC combined with endotracheal aspiration. No evidence of alterations in peak pressures, plateau pressures or respiratory system compliance change was observed after MAC.

CONCLUSIONS

The use of MAC alters respiratory system mechanics, increasing resistive forces by removing secretions. The technique is considered safe and efficacious for postoperative patients. Using MAC in conjunction with endotracheal aspiration provided benefits, achieving the proposed objective: the displacement and removal of airway secretions.

External chest compression in the management of acute severe asthma--a technique in search of evidence

Compelling anecdotal evidence exists for the potentially lifesaving benefits of mechanical external chest compression (MECC), but no published trials of the technique exist. The history and technique for MECC are discussed and illustrated by a case report. Although the technique is not discussed in the Resuscitation Guideline 2000, and the need for it within the intensive care unit has reduced, the use of MECC will have its greatest impact when initiated in the prehospital setting for patients suffering from severe, sudden-onset, asphyxic asthma.