Preliminary effectiveness and feasibility of two pre-operative Inspiratory Muscle Training (IMT) interventions in patients undergoing oesophageal resection

Early post-operative pulmonary complications (PPC), including pulmonary edema,
atelectasis and pneumonia frequently occur after major thoracic surgery
(esophagectomy, pneumonectomy, CABG), especially in high-risk patients (high
age, diabetes, smoking, co-morbidity). The rate of postoperative pulmonary
complications after thoracic surgery such as CABG varies between 20-95% and for
oesophageal resection between 8 to 45 %. PPCs are strongly associated with
prolonged intubations and stay on ICU and general ward, and can have a high
impact on costs of treatment.
Preoperative inspiratory muscle training (IMT) may be beneficial to prevent
PPCs. The aim of preoperative IMT in general is to improve respiratory function
by improving inspiratory muscle strength and/or endurance. The beneficial
effect of preoperative inspiratory muscle endurance training (IMT-endurance) in
high-risk patients undergoing CABG surgery has recently been reported and
consisted of a reduction of postoperative pulmonary complications of almost 50%
after a two to four week respiratory training program, and an improvement in
inspiratory muscle strength of 14.5 mm H20 (=18%). In this study, IMT was
applied as endurance training of the respiratory muscles. However, another
modality of IMT, i.e. high-intensity IMT, aimed at improving lung function by
increasing respiratory muscle strength, has been shown to be beneficial in
healthy adults, in patients with COPD and in chronic heart failure. In these
studies, inspiratory muscle strength increased with 41%, 29% and 31%,
respectively. IMT high -intensity is not used as a preoperative intervention
yet, and its effects on postoperative pulmonary complications are not clear.
However, the effect sizes of IMT high-intensity with respect to inspiratory
muscle strength that have been reported so far indicate that it may be more
beneficial than IMT endurance

Main objective is to examine the preliminary effectiveness of preoperative IMT
high-intensity in patients undergoing oesophagus resection on postoperative
pulmonary complications, inspiratory muscle strength/endurance and IC stay
compared to preoperative IMT -endurance. Secondary objective is to examine the
feasibility (i.e. patient satisfaction, compliance) of preoperative IMT
high-intensity in patients undergoing thoracic surgery (for oesophagus
resection) compared to preoperative IMT -endurance

What are the effects of IMT high intensity on postoperative complications,
inspiratory muscle strength/endurance, stay on IC and general ward, compliance
and patient satisfaction, self-efficacy and anxiety compared to IMT- endurance?

The present pilot study is designed as a randomised, controlled trial with two
arms.
The RCT will include 30 patients per arm and will be performed with a blinded
observer. The setting for the study will be the Centre for Rehabilitation of
the University Medical Centre Groningen, location Groningen

Study arms, (pilot) RCT
-IMT - high intensity group - patients in this group will receive an
inspiratory muscle training programme based on a high intensity protocol.
-IMT - endurance group - patients in this group will receive an inspiratory
muscle training programme based on an endurance protocol.

Measures will be performed before (T0) and after the IMT (T1, pre-operatief),
and during the post-operative period (T2, day 1 to day of discharge)

Both IMT interventions will consist of preoperative, individually tailored
breathing exercises during 3-6 weeks prior to surgery (i.e. the waiting period
for oesophageal resection). The IMT will be given with a Threshold IMT device.
Threshold IMT devices provide a constant, sustained pressure challenge
throughout the entire inspiration that is independent of airflow. When
inspiring through a pressure threshold device, the individual must generate a
minimum inspiratory muscle force to overcome a threshold load by generating an
inspiratory pressure sufficient to open the spring-loaded valve, and must
sustain this pressure level throughout the inspiration. Before starting the
training Maximal Inspiratory Pressure (Pi-max) will be determined.
1)IMT high intensity: This training will be provided as a preoperative
interval-based high-intensity inspiratory muscle training programme. The
training includes 6 cycles of 6 inspiratory breathing manoeuvres on an
inspiratory threshold loading device. Rest times between the cylci are
progressively reduced from 60 seconds to 45, 30, 15 10 and 5 seconds. The
training starts at 60% of the Maximal Inspiratory Pressure (MIP) and will be
increased to 80% in three sessions. Then the load will be increaesd to maximal
load if possible. If patients are able to keep the valve easily open during the
entire session, the load will be increased with 5%. The MIP will be measured
each week to adjust the training intensity to the current level of
performance.The training starts six to three weeks before surgery and will be
performed 3 times a week.
2)IMT endurance. This training will be provided as a preoperative inspiratory
muscle endurance training programme. The training includes 20 minutes breathing
on an inspiratory threshold loading device. The training starts at 30% of the
Maximal Inspiratory Pressure (MIP) and will be increased with 5% if a Borg
score of < 5 is achieved. The training starts six to three weeks before surgery
and will be performed to 7 times a week.
Both training programmes will be performed 3 times a week under supervision of
a physical therapist in the UMCG. Because IMT endurance has been shown to be
feasible and safe, the other sessions can be performed at home.
For the present study both IMT interventions will be delivered with
self-efficacy enhancing techniques. Self-management and/or self-efficacy
enhancing programmes are reported to have beneficial effects on several
health-related outcome measures and quality of life in chronic diseases on
exercise adherence and adoption, and anxiety. The self-management training
program includes goal setting, monitoring, decision making, action, and
feedback. In addition, self-efficacy enhancing techniques such as mastery
experiences, verbal persuasion, and vicarious experiences will be included
during the IMT interventions.

To our knowledge, there are no specific risks associated with this study. The
physical burden for the patients consists of measurements of PI max, lung
volumina (spirometry), and diaphragm function (EMG). In addition, patients have
to fill in four questionnaires which will take approximately 30 minutes to
complete.
Patients have to perform a preoperative inspiratory training programme for 4-6
weeks, 3 times a week, under supervision of a PT in the hospital. Patients may
perceive the training or the travelling as inconvenient, otherwise they may
perceive the supervision and/or the intervention as an extra moment of exertion
of control during a waiting period for a cancer-related surgery which usually
is a period of high anxiety and insecurity. The perception of exertion control
may reduce feeling of anxiety and increase patients* level of self-efficacy.
Furthermore, the benefits for the patients may consist of a reduction of
postoperative pulmonary complications and a shorter IC stay. These benefits are
expected to be equally large in both intervention groups. The investigators do
not expect any undesirable effects of the training program. The subjects might
experience muscle sore following training that will disappear after a couple of
days.