First mobilisation after abdominal and cardiothoracic surgery: when is it actually performed? A national, multicentre, cross-sectional study

OBJECTIVES

Knowledge of clinical practice regarding mobilisation after surgery is lacking. This study therefore aimed to reveal current mobilisation routines after abdominal and cardiothoracic surgery and to identify factors associated with mobilisation within 6 hours postoperatively.

DESIGN

A prospective observational national multicentre study.

SETTING

18 different hospitals in Sweden.

PARTICIPANTS

1492 adult patients undergoing abdominal and cardiothoracic surgery with duration of anaesthesia>2 hours.

PRIMARY AND SECONDARY OUTCOMES

Primary outcome was time to first postoperative mobilisation. Secondary outcomes were the type and duration of the first mobilisation. Data were analysed using multivariate logistic regression and general structural equation modelling, and data are presented as ORs with 95% CIs.

RESULTS

Among the included patients, 52% were mobilised to at least sitting on the edge of the bed within 6 hours, 70% within 12 hours and 96% within 24 hours. Besides sitting on the edge of the bed, 76% stood up by the bed and 22% were walking away from the bedside the first time they were mobilised. Patients undergoing major upper abdominal surgery required the longest time before mobilisation with an average time of 11 hours post surgery. Factors associated with increased likelihood of mobilisation within 6 hours of surgery were daytime arrival at the postoperative recovery unit (OR: 5.13, 95% CI: 2.16 to 12.18), anaesthesia <4 hours (OR: 1.68, 95% CI: 1.17 to 2.40) and American Society of Anaesthesiologists (ASA) classification 1-2, (OR: 1.63, 95% CI: 1.13 to 2.36).

CONCLUSIONS

In total, 96% if the patients were mobilised within 24 hours after surgery and 52% within 6 hours. Daytime arrival at the postoperative recovery unit, low ASA classification and shorter duration of anaesthesia were associated with a shorter time to mobilisation.

TRIAL REGISTRATION NUMBER

FoU, Forskning och Utveckling in VGR, Vastra Gotaland Region (Id:275357) and Clinical Trials (NCT04729634).

Inspiratory Capacity as an Indirect Measure of Immediate Effects of Positive Expiratory Pressure and CPAP Breathing on Functional Residual Capacity in Healthy Subjects

BACKGROUND

Positive expiratory pressure (PEP) and CPAP are used to enhance breathing parameters such as functional residual capacity (FRC) in patients. Studies comparing effects of PEP and CPAP on FRC are few and variable. One reason for this may be that sophisticated equipment, not suitable in the clinical setting, is required. Because total lung capacity (TLC) consists of inspiratory capacity (IC) and FRC, a change in IC should result in a corresponding change in FRC given constant TLC. We aimed to evaluate the effects of different PEP and CPAP devices on IC as an indirect measure of induced changes in FRC from these devices in healthy subjects.

METHODS

Twenty healthy subjects breathed with 2 PEP devices, a PEP mask (flow resistor) and a PEP bottle (threshold resistor), and 2 CPAP devices, a flow resistor and a threshold resistor, in a randomized order. The measurement sequence consisted of 30 breaths with an IC measurement performed before and immediately after the 30th breath while the subjects were still connected to the breathing device. Perceived exertion of the 30 breaths was measured with the Borg category ratio 10 scale.

RESULTS

Three of the 4 breathing devices, the PEP mask and the 2 CPAP devices, significantly decreased IC (P < .001). Median perceived exertion was quite low for all 4 breathing devices, but the difference in perceived exertion among the different breathing devices was large.

CONCLUSIONS

Provided that TLC is constant, we found that measurements of changes in IC could be used as an indirect measure of changes in FRC in healthy subjects. All investigated breathing devices except the PEP bottle decreased IC, as an indirect measure of increased FRC.

Simulated flying altitude and performance of continuous positive airway pressure devices

INTRODUCTION

Continuous positive airway pressure (CPAP) is used in air ambulances to treat patients with impaired oxygenation. Differences in mechanical principles between CPAP devices may affect their performance at different ambient air pressures, as will occur in an air ambulance during flight.

METHODS

Two different CPAP systems, a threshold resistor device and a flow resistor device, at settings of 5 and 10 cm H₂O were examined. Static pressure, static airflow, and pressure during simulated breathing were measured at ground level and at three different altitudes [2400 m (7874 ft), 3000 m (9843 ft), and 10,700 m (35,105 ft)].

RESULTS

When altitude increased, the performance of the two CPAP systems differed during both static and simulated breathing pressure measurements. With the threshold resistor CPAP, measured pressure levels were close to the preset CPAP level. Static pressure decreased 0.71 ± 0.35 cm H₂O at CPAP 10 cm H₂O compared to ground level and 35,105 ft (10,700 m). With the flow resistor CPAP, as the altitude increased, CPAP produced pressure levels increased. At 35,105 ft (10,700 m), the increase was 5.13 ± 0.33 cm H₂O at CPAP 10 cm H₂O.

DISCUSSION

The velocity of airflow through the flow resistor CPAP device is strongly influenced by reduced ambient air pressure, leading to a higher delivered CPAP effect than the preset CPAP level. Threshold resistor CPAP devices seem to have robust performance regardless of altitude. Thus, the threshold resistor CPAP device is probably more appropriate for CPAP treatment in an air ambulance cabin, where ambient pressure will vary during patient transport.

Pneumatic performance of the Boussignac CPAP system in healthy humans

BACKGROUND

The Boussignac continuous positive airway pressure (CPAP) device effectively treats acute pulmonary edema, but data on airway pressure with the Boussignac CPAP system are sparse.

OBJECTIVE

To evaluate the Boussignac CPAP system's ability to maintain stable inspiratory and expiratory pressure levels, and to evaluate perceived exertion during breathing with the Boussignac CPAP system.

METHODS

With 18 healthy volunteers we recorded airway pressure and air flow during 10-min sessions at 5.0, 7.5, and 10.0 cm H(2)O. The participants were blinded to the sequence of the CPAP levels. Each session was ended with 10 forced breaths. We measured perceived exertion with the Borg category ratio 10 (Borg CR10) scale.

RESULTS

When the participants breathed at 20% of vital capacity and a peak expiratory flow of 14% of FEV(1), the maximum pressure difference between inspiration and expiration was 4.0 cm H(2)O at CPAP 10 cm H(2)O. The changes in airway pressure were never large enough to reduce airway pressure to below zero. During the forced breaths, the expiratory volume was 38-42% of vital capacity and peak expiratory flow was 49-56% of FEV(1). As air flow increased, both the drop in inspiratory airway pressure and the increase in expiratory airway pressure increased.

CONCLUSIONS

With CPAP, pressure changes are considered to be associated with increased work of breathing. The device's pneumatic performance is adequate during normal breathing with low air flow, but during forced breathing (high air flow) it did not maintain stable airway pressure, which could increase the work of breathing and cause respiratory fatigue. Thus, the Boussignac CPAP system might be less suitable for a patient breathing at a higher frequency.

Physiological responses to positive expiratory pressure breathing: a comparison of the PEP bottle and the PEP mask

BACKGROUND

In the intensive care unit we have observed that patients have different adherence to 2 commonly used positive-expiratory-pressure (PEP) therapy devices: the PEP bottle and the PEP mask. The reason for this difference is not clear.

METHODS

In a randomized prospective study, we made continuous recordings of airway pressure and airflow, with 20 healthy volunteers, with the PEP bottle and the PEP mask. The measurement sequence consisted of 3 sessions of 10 breaths with the PEP bottle and the PEP mask, in a randomized crossover design. A rest period of 15 min separated the PEP bottle and PEP mask measurements.

RESULTS

With the PEP bottle the expiratory phase began with a zero-flow period of 0.39 s, during which airway pressure rose 11.9 cm H2O. With the PEP bottle the mean expiratory pressure was 11.7 cm H2O, and end-expiratory pressure was 9.5 cm H2O. With the PEP mask the initial expiratory zero-flow period was almost nonexistent (0.04 s) and without any change in airway pressure. With the PEP mask the shape of the expiratory pressure curve was different; mean expiratory pressure was 8.6 cm H2O, and end-expiratory pressure was zero. With the PEP bottle the inspiration also began with a zero-flow period of 0.43 s, during which airway pressure decreased 9.6 cm H2O from the end-expiratory airway pressure. With the PEP mask the initial inspiratory zero-flow period was only 0.01 s and there was no concomitant change in airway pressure.

CONCLUSIONS

The PEP bottle and the PEP mask showed major differences in the relationship between airflow and airway pressure. These findings might explain the observed differences in patient adherence to these therapies.