Maximum inspiratory pressure, a surrogate parameter for the assessment of ICU-acquired weakness

Impacts of three inspiratory muscle training programs on inspiratory muscles strength and endurance among intubated and mechanically ventilated patients with difficult weaning: a multicentre randomised controlled trial

BACKGROUND

Inspiratory muscle training (IMT) is well-established as a safe option for combating inspiratory muscles weakness in the intensive care setting. It could improve inspiratory muscle strength and decrease weaning duration but a lack of knowledge on the optimal training regimen raise to inconsistent results. We made the hypothesis that an innovative mixed intensity program for both endurance and strength improvement could be more effective. We conducted a multicentre randomised controlled parallel trial comparing the impacts of three IMT protocols (low, high, and mixed intensity) on inspiratory muscle strength and endurance among difficult-to-wean patients.

METHODS

Ninety-two patients were randomly assigned to three groups with different training programs, where each performed an IMT program twice daily, 7 days per week, from inclusion until successful extubation or 30 days. The primary outcome was maximal inspiratory pressure (MIP) increase. Secondary outcomes included peak pressure (Ppk) increase as an endurance marker, mechanical ventilation (MV) duration, ICU length of stay, weaning success defined by a 2-day ventilator-free after extubation, reintubation rate and safety.

RESULTS

MIP increases were 10.8 ± 11.9 cmH2O, 4.5 ± 14.8 cmH2O, and 6.7 ± 14.5 cmH2O for the mixed intensity (MI), low intensity (LI), and high intensity (HI) groups, respectively. There was a non-statistically difference between the MI and LI groups (mean adjusted difference: 6.59, 97.5% CI [- 14.36; 1.18], p = 0.056); there was no difference between the MI and HI groups (mean adjusted difference: - 3.52, 97.5% CI [- 11.57; 4.53], p = 0.321). No significant differences in Ppk increase were observed among the three groups. Weaning success rate observed in MI, HI and LI group were 83.7% [95% CI 69.3; 93.2], 82.6% [95% CI 61.2; 95.0] and 73.9% [95% CI 51.6; 89.8], respectively. MV duration, ICU length of stay and reintubation rate had similar values. Over 629 IMT sessions, six adverse events including four spontaneously reversible bradycardia in LI group were possibly related to the study.

CONCLUSIONS

Among difficult-to-wean patients receiving invasive MV, no statistically difference was observed in strength and endurance progression across three different IMT programs. IMT appears to be feasible in usual cares, but some serious adverse events such as bradycardia could motivate further research on the specific impact on cardiac system. Trial registration Clinicaltrials.gov identifier: NCT02855619. Registered 28 September 2014.

Increasing role of post-intensive care syndrome in quality of life of intensive care unit survivors

In this editorial we comment on the detrimental consequences that post-intensive care syndrome (PICS) has in the quality of life of intensive care unit (ICU) survivors, highlighting the importance of early onset of multidisciplinary rehabilitation from within the ICU. Although, the syndrome was identified and well described early in 2012, more awareness has been raised on the long-term PICS related health problems by the increased number of coronavirus disease 2019 ICU survivors. It is well outlined that the syndrome affects both the patient and the family and is described as the appearance or worsening of impairment in physical, cognitive, or mental health as consequence of critical illness. PICS was described in order: (1) To raise awareness among clinicians, researchers, even the society; (2) to highlight the need for a multilevel screening of these patients that starts from within the ICU and continues after discharge; (3) to present preventive strategies; and (4) to offer guidelines in terms of rehabilitation. An early multidisciplinary approach is the key element form minimizing the incidence of PICS and its consequences in health related quality of life of both survivors and their families.

The effect of spinal versus general anaesthesia on perioperative muscle weakness in patients having bilateral total hip arthroplasty: a single center randomized clinical trial

BACKGROUND

Perioperative neuro-endocrine stress response may contribute to acquired muscle weakness. Regional anaesthesia has been reported to improve the outcome of patients having total hip arthroplasty. In this study, it was hypothesized that spinal anaesthesia (SA) decreases the perioperative neuro-endocrine stress response and perioperatively acquired muscle weakness (PAMW), as compared to general anaesthesia (GA).

METHODS

Fifty subjects undergoing bilateral total hip arthroplasty (THA) were randomly allocated to receive a standardized SA (n = 25) or GA (n = 25). Handgrip strength was assessed preoperatively, on the first postoperative day (primary endpoint) and on day 7 and 28. Respiratory muscle strength was measured by maximal inspiratory pressure (MIP). Stress response was assessed by measuring levels of Adrenocorticotropic hormone (ACTH), cortisol and interleukin-6 (IL-6).

RESULTS

Handgrip strength postoperatively (day 1) decreased by 5.4 ± 15.9% in the SA group, versus 15.2 ± 11.7% in the GA group (p = 0.02). The handgrip strength returned to baseline at day 7 and did not differ between groups at day 28. MIP increased postoperatively in patients randomized to SA by 11.7 ± 48.3%, whereas it decreased in GA by 12.2 ± 19.9% (p = 0.04). On day 7, MIP increased in both groups, but more in the SA (49.0 ± 47.8%) than in the GA group (14.2 ± 32.1%) (p = 0.006). Postoperatively, the levels of ACTH, cortisol and IL-6 increased in the GA, but not in the SA group (p < 0.004).

CONCLUSION

In patients having bilateral THA, SA preserved the postoperative respiratory and peripheral muscle strength and attenuated the neuro-endocrine and inflammatory responses.

TRIAL REGISTRATION

clinicaltrials.gov NCT03600454.

Respiratory Monitoring During Mechanical Ventilation: The Present and the Future

The increased application of mechanical ventilation, the recognition of its harms and the interest in individualization raised the need for an effective monitoring. An increasing number of monitoring tools and modalities were introduced over the past 2 decades with growing insight into asynchrony, lung and chest wall mechanics, respiratory effort and drive. They should be used in a complementary rather than a standalone way. A sound strategy can guide a reduction in adverse effects like ventilator-induced lung injury, ventilator-induced diaphragm dysfunction, patient-ventilator asynchrony and helps early weaning from the ventilator. However, the diversity, complexity, lack of expertise, and associated cost make formulating the appropriate monitoring strategy a challenge for clinicians. Most often, a big amount of data is fed to the clinicians making interpretation difficult. Therefore, it is fundamental for intensivists to be aware of the principle, advantages, and limits of each tool. This analytic review includes a simplified narrative of the commonly used basic and advanced respiratory monitors along with their limits and future prospective.

Assessment of motor limb strength by neuroscience nurses: variations in practice and associated challenges

BACKGROUND

Limb strength is a central component of neurological assessment and monitoring in nursing practice, yet there is a lack of research examining the tools used by nurses or challenges nurses encounter when using these tools. The evidence base is lacking to inform effective practice and the underpinning educational approaches.

AIM

To determine which tools are used by UK and Irish neuroscience nurses in the assessment of limb strength and the associated challenges and variations in practice.

METHODS

This study used an online self-reported survey design to ascertain which tools neuroscience nurses used and their experience of using these (n=160).

FINDINGS

Practices varied, with a dominance of two tools being used in practice: the Medical Research Council scale and the 'normal power' to 'no movement' scale found on the neurological observation chart. Most respondents used the same tool across all conditions.

CONCLUSION

This study highlights variations in assessment practice and the absence of a sound evidence base behind choice of motor limb strength assessment tools used.

Intensive Care Unit-acquired Weakness: A Frequent but Under-recognized Threat

How to cite this article: Sapra H. Intensive Care Unit-acquiredWeakness: A Frequent but Under-recognized Threat. Indian J Crit Care Med 2021;25(9):969-971.

Use of Organ Dysfunction as a Primary Outcome Variable Following Cecal Ligation and Puncture: Recommendations for Future Studies

Outcomes variables for research on sepsis have centered on mortality and changes in the host immune response. However, a recent task force (Sepsis-3) revised the definition of sepsis to "life-threatening organ dysfunction caused by a dysregulated host response to infection." This new definition suggests that human studies should focus on organ dysfunction. The appropriate criteria for organ dysfunction in either human sepsis or animal models are, however, poorly delineated, limiting the potential for translation. Further, in many systems, the difference between "dysfunction" and "injury" may not be clear. In this review, we identify criteria for organ dysfunction and/or injury in human sepsis and in rodents subjected to cecal ligation and puncture (CLP), the most commonly used animal model of sepsis. We further examine instances where overlap between human sepsis and CLP is sufficient to identify translational endpoints. Additional verification may demonstrate that these endpoints are applicable to other animals and to other sepsis models, for example, pneumonia. We believe that the use of these proposed measures of organ dysfunction will facilitate mechanistic studies on the pathobiology of sepsis and enhance our ability to develop animal model platforms to evaluate therapeutic approaches to human sepsis.

Medical Research Council Scale Predicts Spontaneous Breathing Trial Failure and Difficult or Prolonged Weaning of Critically Ill Individuals

BACKGROUND

Handgrip strength is an alternative measure to assess peripheral muscle strength and is correlated with the Medical Research Council (MRC) scale, with promising values for diagnosing ICU-acquired weakness (ICUAW). Because ICUAW has been associated with delayed weaning from mechanical ventilation, we hypothesized that ICUAW evaluated with both the MRC scale score and handgrip strength are associated with failure of a spontaneous breathing trial (SBT) and duration of mechanical ventilation weaning.

METHODS

We conducted a prospective observational study in 3 general ICUs with a total of 54 beds at 2 academic hospitals. Adult subjects with > 48 h of mechanical ventilation who were eligible for weaning were included in the study.

RESULTS

In the evaluation before the first SBT, the MRC score (P < .001) and handgrip strength (P < .001) were significantly different between subjects extubated after a successful first SBT (simple weaning) and those extubated any time after a failed first SBT (difficult weaning). Only the MRC score discriminated between first SBT success or failure (P < .001); in multivariate analysis, the MRC score was significantly associated with first SBT failure (odds ratio 0.91, 95% CI 0.88-0.97, P < .001) and difficult weaning (odds ratio 0.91, 95% CI 0.87-0.96, P < .001). Handgrip strength exhibited good accuracy in identifying ICUAW.

CONCLUSIONS

MRC score was independently associated with SBT failure and difficult or prolonged weaning.

Chinesisation, adaptation and validation of the Chelsea Critical Care Physical Assessment Tool in critically ill patients: a cross-sectional observational study

PURPOSE

To translate and adapt the Chelsea Critical Care Physical Assessment Tool (CPAx) into Chinese version ('CPAx-Chi'), test the reliability and validity of CPAx-Chi, and verify the cut-off point for the diagnosis of intensive care unit-acquired weakness (ICU-AW).

STUDY DESIGN

Cross-sectional observational study.

METHODS

Forward and back translation, cross-cultural adaptation and pretesting of CPAx into CPAx-Chi were based on the Brislin model. Participants were recruited from the general ICU of five third-grade class-A hospitals in western China. Two hundred critically ill adult patients (median age: 53 years; 64% men) with duration of ICU stay ≥48 hours and Glasgow Coma Scale ≥11 were included in this study. Two researchers simultaneously and independently assessed eligible patients using the Medical Research Council Muscle Score (MRC-Score) and CPAx-Chi.

RESULTS

The content validity index of items was 0.889. The content validity index of scale was 0.955. Taking the MRC-Score scale as standard, the criterion validity of CPAx-Chi was r=0.758 (p<0.001) for researcher A, and r=0.65 (p<0.001) for researcher B. Cronbach's α was 0.939. The inter-rater reliability was 0.902 (p<0.001). The area under the receiver operating characteristic curves of CPAx-Chi for diagnosing ICU-AW based on MRC-Score ≤48 were 0.899 (95% CI 0.862 to 1.025) and 0.874 (95% CI 0.824 to 0.925) for researcher B. The best cut-off point for CPAx-Chi for the diagnosis of ICU-AW was 31.5. The sensitivity was 87% and specificity was 77% for researcher A, whereas it was 0.621, 31.5, 75% and 87% for researcher B, respectively. The consistency was high when taking CPAx-Chi ≤31 and MRC-Score ≤48 as the cut-off points for the diagnosis of ICU-AW. Cohen's kappa=0.845 (p=0.02) in researcher A and 0.839 (p=0.04) for researcher B.

CONCLUSIONS

CPAx-Chi demonstrated content validity, criterion-related validity and reliability. CPAx-Chi showed the best accuracy in assessment of patients at risk of ICU-AW with good sensitivity and specificity at a recommended cut-off of 31.

Handgrip Force and Maximum Inspiratory and Expiratory Pressures in Critically Ill Patients With a Tracheostomy

BACKGROUND

The association between peripheral striated muscle strength and respiratory muscle strength has been confirmed in a number of disorders. However, this association is unknown in intensive care unit patients with tracheostomies.

OBJECTIVE

To examine correlations between handgrip force, maximum inspiratory pressure (MIP), and maximum expiratory pressure (MEP) in intensive care unit patients with tracheostomies.

METHODS

Twenty patients (7 women, 13 men) with tracheostomies, in the intensive care unit longer than 11 days, in stable condition, with functional limbs, and with Glasgow Coma Scale scores of 15 were recruited. Both MIP and MEP were measured with a membrane manometer; handgrip force was measured with a hydraulic hand dynamometer.

RESULTS

Handgrip force was significantly correlated with MIP (r = 0.45, P = .04) and MEP (r = 0.78, P = .001). Handgrip force was significantly predicted by MIP and MEP when the effect of sex was controlled for (P < .05). However, when MIP and MEP were included as predictors in a regression model, MEP was the only significant predictor (R = 0.80, R2 = 0.63, adjusted R2 = 0.57).

CONCLUSIONS

Strength of the hand flexors and strength of the expiratory muscles (abdominal) were significantly correlated in intensive care unit patients. Handgrip strength appears to be an easy, fast way to evaluate expiratory muscle strength by using a simple handhold command without special equipment. A strong handhold may also correspond to strong expiratory muscles. ClinicalTrials.gov: NCT03457376.

ICU outcomes can be predicted by noninvasive muscle evaluation: a meta-analysis

BACKGROUND

The relationship between muscle function in critically ill patients assessed using bedside techniques and clinical outcomes has not been systematically described. We aimed to evaluate the association between muscle weakness assessed by bedside evaluation and mortality or weaning from mechanical ventilation, and the capacity of each evaluation tool to predict outcomes.

METHODS

Five databases (PubMed, Embase, CINAHL, Cochrane Library, Science Direct) were searched from January 2000 to December 2018. Data were extracted and random effects meta-analyses were performed.

RESULTS

60 studies were analysed, including 4382 patients. Intensive care unit (ICU)-related muscle weakness was associated with an increase in overall mortality with odds ratios ranging from 1.2 (95% CI 0.60-2.40) to 4.48 (95% CI 1.49-13.42). Transdiaphragmatic twitch pressure had the highest predictive capacity for overall mortality, with a sensitivity of 0.87 (95% CI 0.76-0.93) and a specificity of 0.36 (95% CI 0.27-0.43). The area under the curve (AUC) was 0.74 (95% CI 0.70-0.78). Muscle weakness was associated with an increase in mechanical ventilation weaning failure rate with an odds ratio ranging from 2.64 (95% CI 0.72-9.64) to 19.07 (95% CI 9.35-38.9). Diaphragm thickening fraction had the highest predictive capacity for weaning failure with a sensitivity of 0.76 (95% CI 0.67-0.83) and a specificity of 0.86 (95% CI 0.78-0.92). The AUC was 0.86 (95% CI 0.83-0.89).

CONCLUSION

ICU-related muscle weakness detected by bedside techniques is a serious issue associated with a high risk of death or prolonged mechanical ventilation. Evaluating diaphragm function should be a clinical priority in the ICU.

The combination of inspiratory muscle training and high-flow nasal cannula oxygen therapy for promoting weaning outcomes in difficult-to-wean patients: protocol for a randomised controlled trial

Background

According to the literature, 20-30% of intubated patients are difficult to wean off mechanical ventilation and have a prolonged intensive care unit (ICU) stay with detrimental effects on muscle strength, functional ability and quality of life. Inspiratory muscle training (IMT) via a threshold device has been proposed as an effective exercise for minimising the effects of mechanical ventilation on respiratory muscles of critically ill patients with prolonged weaning. In addition, high-flow nasal cannula (HFNC) oxygen has been proved to provide efficient support for both high- and low-risk patients after extubation, thus preventing re-intubation.

Material and methods

A randomised controlled trial was designed to assess the efficacy of combining IMT and HFNC as therapeutic strategies for patients with high risk for weaning failure. Once patients with prognostic factors of difficult weaning are awake, ventilated with support settings and cooperative, they will be randomised to one of the two following study groups: intervention group (IMT and HFNC) and control group (IMT and Venturi mask). IMT will start as soon as possible. Each allocated oxygen delivery device will be applied immediately after extubation. IMT intervention will continue until patients' discharge from ICU. The primary outcome is the rate of weaning failure. Secondary outcomes are maximal inspiratory and expiratory strength, endurance of respiratory muscles, global muscle strength, functional ability and quality of life along with duration of ventilation (days) and ICU and hospital length of stay.

Conclusion

The present study could significantly contribute to knowledge of how best to treat patients with difficult weaning and high risk of re-intubation.

Effect of early activity combined with early nutrition on acquired weakness in ICU patients

INTRODUCTION

Intensive care unit-acquired weakness (ICU-AW) occurs in 25% to 100% of critically ill patients, and is associated with prolonged mechanical ventilation, extended ICU stay, and total hospital stay, increased hospital costs, higher risk of death, impaired physical function, and decreased quality of life. However, there are not any current guidelines that mention management of ICU-AW. The present study will evaluate the effects of a combination of early nutrition and early exercise compared to those of either early exercise alone or the standard care for patients in ICUs.

METHODS

This is a 3-arm, parallel, randomized controlled trial including an estimated 147 critically ill patients aged ≥18 years recruited from the ICUs of 2 hospitals in Heilongjiang, China. Patients will be prospectively randomized 1:1:1 to receive early mobilization, early nutrition combined with early mobilization, or standard care (minimal exercises, experience-based initiation and enrollment of nutrition support). Outcomes are assessed at ICU discharge after baseline. The primary outcome is occurrence of ICU-AW according to the Medical Research Council scale at the end of treatment. Muscle strength, organ failure, functional independence, self-care ability, time of ICU stay, duration of mechanical ventilation, and ICU mortality are secondary outcome measures.

DISCUSSION

This trial has the potential to identify a novel strategy for preventing or managing ICU-AW. The findings may increase the clinical knowledge about nutrition and mobilization interventions for people with ICU-AW, and contribute to the formation of practice guidelines for managing this condition.

TRIAL REGISTRATION NUMBER

ChiCTR2000033482.

Respiratory Muscle Rehabilitation in Patients with Prolonged Mechanical Ventilation: A Targeted Approach

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2020. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2020. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Critical illness polyneuromyopathy in septic patients: Is it possible to diagnose it in a bedside clinical examination?

OBJECTIVE

To determine the sensitivity and specificity of peripheral and respiratory muscle strength tests in diagnosing critical illness polyneuromyopathy (CIPNM), compared with an electrophysiological examination.

METHODS

Fifty septic patients who required mechanical ventilation for at least five days, and without a previous history of muscle weakness, were included. Peripheral muscle strength was assessed using the Medical Research Council (MRC) score, handgrip strength by dynamometry, and respiratory muscle strength with maximum respiratory pressures. Diagnosis of CIPNM was either confirmed or rejected by an electrophysiological examination. Receiver operating characteristic curve analysis was performed to determine the cut-off values with the best sensitivity (SN) and specificity (SP) of the studied variables in the presence or absence of CIPNM.

RESULTS

Patients with CIPNM were older, more critical (APACHE IV/SAPS 3), had a longer hospitalization, required mechanical ventilation for longer, and had a higher rate of intensive care unit readmission. Cutoff values identified CIPNM patients using MRC scores, dynamometry according to sex, maximal expiratory and inspiratory pressures, as well as being confirmed by the electrophysiological examination, with good sensitivity and specificity: < 40 (SN: 0.893; SP: 0.955); < 7 kg (SN: 1; SP: 0.909) for men, < 4 kg (SN: 0.882; SP: 1) for women; < 34 cmH2O (SN: 0.808; SP: 0.909) and > -40 cmH2O (SN: 0.846; SP: 0.909), respectively.

CONCLUSION

The MRC score, dynamometry or maximum respiratory pressures can be used to identify patients with CIPNM at the intensive care bedside assessment. The healthcare professional can choose any of the methods studied to evaluate the patient, based on his experience and the resource available.

Pulmonary and Physical Rehabilitation in Critically Ill Patients

Some patients admitted to the intensive care unit (ICU) because of an acute illness, complicated surgery, or multiple traumas develop muscle weakness affecting the limbs and respiratory muscles during acute care in the ICU. This condition is referred to as ICU-acquired weakness (ICUAW), and can be evoked by critical illness polyneuropathy (CIP), critical illness myopathy (CIM), or critical illness polyneuromyopathy (CIPNM). ICUAW is diagnosed using the Medical Research Council (MRC) sum score based on bedside manual muscle testing in cooperative patients. The MRC sum score is the sum of the strengths of the 12 regions on both sides of the upper and lower limbs. ICUAW is diagnosed when the MRC score is less than 48 points. However, some patients require electrodiagnostic studies, such as a nerve conduction study, electromyography, and direct muscle stimulation, to differentiate between CIP and CIM. Pulmonary rehabilitation in the ICU can be divided into modalities intended to remove retained airway secretions and exercise therapies intended to improve respiratory function. Physical rehabilitation, including early mobilization, positioning, and limb exercises, attenuates the weakness that occurs during critical care. To perform mobilization in mechanically ventilated patients, pretreatment by removing secretions is necessary. It is also important to increase the strength of respiratory muscles and to perform lung recruitment to improve mobilization in patients who are weaned from the ventilator. For these reasons, pulmonary rehabilitation is important in addition to physical therapy. Early recognition of CIP, CIM, and CIPNM and early rehabilitation in the ICU might improve patients’ functional recovery and outcomes.

Association between hand grip strength with weaning and intensive care outcomes in COPD patients: A pilot study

BACKGROUND

In COPD, weight loss and muscle wasting contribute significantly to morbidity, disability, and handicap. Dominant-handgrip strength for evaluation of muscle strength has not been tested as a parameter to predict outcome of weaning from mechanical ventilation (MV).

OBJECTIVES

To evaluate the association between handgrip strength and the duration and success of weaning and extubation outcome.

MATERIALS AND METHODS

This prospective study included 34 COPD patients requiring MV for at least 48 hours. Recovery from sedation and muscle relaxants was assessed before recruitment. Serial meseaurment of handgrip strength were assessed by trained personnel.

RESULTS

There was a significant negative correlation between baseline hand grip and duration of MV (P = .047, r = -.343). The mean day 5 hand grip was significantly lower in person who died compared to survivors (5.7 ± 5.5 vs 18.2 ± 14.5, P = .044). The mean day 5 hand grip was significantly lower in patients who needed reintubation compared to those in patients who did not need reintubation (2.8 ± 2 vs 17.2 ± 13.9, P = .029). There was no significant difference in the mean baseline, day 2, day 3, day 4 and day 5 hand grip in weaning success compared to those in failure (P > .05).

CONCLUSION

Handgrip strength may be good predictor for duration of MV, extubation outcome, ICU mortality and prognosis.

Análise da força muscular expiratória e respiração espontânea de indivíduos em ventilação mecânica: estudo transversal

RESUMO Os músculos da expiração têm funções em todo o ciclo respiratório, mas não são frequentemente avaliados no desmame da ventilação mecânica. Assim, revisões e consensos não mencionam a pressão expiratória máxima (PEmáx) e o treino expiratório. Objetivou-se investigar a relação da força muscular expiratória com a respiração espontânea de indivíduos ventilados mecanicamente. Trata-se de um estudo transversal com participantes de 18 a 79 anos de idade. Foram formados os grupos PEmáx satisfatória (GPES) e PEmáx baixa (GPEB) conforme o ponto de corte de 55cmH2O e comparados a parâmetros de desmame. O GPES (n=9) teve desempenho superior ao do GPEB (n=21) no índice de respiração rápida e superficial (IRRS) (40,6±17,6rpm/L e 75,3±44,1rpm/L, respectivamente; p=0,022) e na frequência respiratória (f) (19,1±6,2rpm e 26,1±9,4rpm; p=0,044). A prevalência de PEmáx satisfatória foi pequena, observada no tamanho dos grupos. Além disso, embora a PEmáx percentual do valor predito tenha sido menor no GPEB, como esperado (67,2±15,4% vs. 45,8±14,7%; p=0,001), a pressão inspiratória máxima percentual não diferiu significantemente (82,4±21,8% vs. 67,8±18,4%; p=0,077). A PEmáx se correlacionou moderadamente com o IRRS (r=-0,406; p=0,026) e com a f (r=-0,426; p=0,017). Conclui-se que a PEmáx≥55cmH2O esteve associada à melhores valores no IRRS e na f, e que a redução da força muscular expiratória foi mais prevalente e severa que a da força muscular inspiratória.

Weakness acquired in the intensive care unit. Incidence, risk factors and their association with inspiratory weakness. Observational cohort study

OBJECTIVE

This paper sought to determine the accumulated incidence and analyze the risk factors associated with the development of weakness acquired in the intensive care unit and its relationship to inspiratory weakness.

METHODS

We conducted a prospective cohort study at a single center, multipurpose medical-surgical intensive care unit. We included adult patients who required mechanical ventilation ≥ 24 hours between July 2014 and January 2016. No interventions were performed. Demographic data, clinical diagnoses, the factors related to the development of intensive care unit -acquired weakness, and maximal inspiratory pressure were recorded.

RESULTS

Of the 111 patients included, 66 developed intensive care unit -acquired weakness, with a cumulative incidence of 40.5% over 18 months. The group with intensive care unit-acquired weakness were older (55.9 ± 17.6 versus 45.8 ± 16.7), required more mechanical ventilation (7 [4 - 10] days versus 4 [2 - 7.3] days), and spent more time in the intensive care unit (15.5 [9.2 - 22.8] days versus 9 [6 - 14] days). More patients presented with delirium (68% versus 39%), hyperglycemia > 3 days (84% versus 59%), and positive balance > 3 days (73.3% versus 37%). All comparisons were significant at p < 0.05. A multiple logistic regression identified age, hyperglycemia ≥ 3 days, delirium, and mechanical ventilation > 5 days as independent predictors of intensive care unit-acquired weakness. Low maximal inspiratory pressure was associated with intensive care unit-acquired weakness (p < 0.001), and the maximum inspiratory pressure cut-off value of < 36cmH2O had sensitivity and specificity values of 31.8% and 95.5%, respectively, when classifying patients with intensive care unit-acquired weakness.

CONCLUSION

The intensive care unit acquired weakness is a condition with a high incidence in our environment. The development of intensive care unit-acquired weakness was associated with age, delirium, hyperglycemia, and mechanical ventilation > 5 days. The maximum inspiratory pressure value of ≥ 36cmH2O was associated with a high diagnostic value to exclude the presence of intensive care unit -acquired weakness.

Correlation of maximal inspiratory pressure to transdiaphragmatic twitch pressure in intensive care unit patients

Background

Respiratory muscle weakness contributes to respiratory failure in ICU patients. Unfortunately, assessment of weakness is difficult since the most objective test, transdiaphragmatic pressure in response to phrenic nerve stimulation (PdiTw), is difficult to perform. While most clinicians utilize maximum inspiratory pressure (Pimax) to assess strength, the relationship of this index to PdiTw has not been evaluated in a large ICU population. The purpose of the present study was to assess both PdiTw and Pimax in ICU patients to determine how these indices correlate with each other, what factors influence these indices, and how well these indices predict outcomes.

Methods

Studies were performed on adult mechanically ventilated patients in the University of Kentucky MICU (n = 60). We assessed PdiTw by measuring transdiaphragmatic pressure (Pdi) in response to bilateral twitch stimulation of the phrenic nerves using dual magnetic stimulators (Magstim 200). Pimax was determined by measuring airway pressure during a 30-second inspiratory occlusion. We also assessed the twitch and maximum force generation for diaphragms excised from control and septic mice.

Results

Both Pimax and PdiTw measurements were profoundly reduced for mechanically ventilated MICU patients when compared to normal reference values, e.g., Pimax averaged 56 % of the predicted value for normal subjects. For the ICU population as a whole, PdiTw and Pimax values correlated with each other (r² = 0.373, p < 0.001), but there was wide scatter and, as a result, PdiTw could not be reliably calculated from Pimax levels for individual subjects. Infection selectively reduced low-frequency force generation more than high-frequency force generation for both our mouse experiments (comparing muscle twitch to 150 Hz tetanic force) and for MICU patients (comparing PdiTw to Pimax). This effect of infection may contribute to scatter in the PdiTw to Pimax relationship. We also found that both PdiTw and Pimax were significantly correlated with both patient survival and the duration of mechanical ventilation, albeit statistically, PdiTw was the better predictor.

Conclusions

While more difficult to measure, the PdiTw is a better predictor of outcomes in mechanically ventilated MICU patients than the Pimax. Nevertheless, for some clinical applications, the Pimax determination is a reasonable alternative.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-016-1247-z) contains supplementary material, which is available to authorized users.

Unidirectional Expiratory Valve Method to Assess Maximal Inspiratory Pressure in Individuals without Artificial Airway

Introduction

Maximal Inspiratory Pressure (MIP) is considered an effective method to estimate strength of inspiratory muscles, but still leads to false positive diagnosis. Although MIP assessment with unidirectional expiratory valve method has been used in patients undergoing mechanical ventilation, no previous studies investigated the application of this method in subjects without artificial airway.

Objectives

This study aimed to compare the MIP values assessed by standard method (MIP_sta) and by unidirectional expiratory valve method (MIP_uni) in subjects with spontaneous breathing without artificial airway. MIP_uni reproducibility was also evaluated.

Methods

This was a crossover design study, and 31 subjects performed MIP_sta and MIP_uni in a random order. MIP_sta measured MIP maintaining negative pressure for at least one second after forceful expiration. MIP_uni evaluated MIP using a unidirectional expiratory valve attached to a face mask and was conducted by two evaluators (A and B) at two moments (Tests 1 and 2) to determine interobserver and intraobserver reproducibility of MIP values. Intraclass correlation coefficient (ICC_[2,1]) was used to determine intraobserver and interobserver reproducibility.

Results

The mean values for MIP_uni were 14.3% higher (-117.3 ± 24.8 cmH₂O) than the mean values for MIP_sta (-102.5 ± 23.9 cmH₂O) (p<0.001). Interobserver reproducibility assessment showed very high correlation for Test 1 (ICC_[2,1] = 0.91), and high correlation for Test 2 (ICC_[2,1] = 0.88). The assessment of the intraobserver reproducibility showed high correlation for evaluator A (ICC_[2,1] = 0.86) and evaluator B (ICC_[2,1] = 0.77).

Conclusions

MIP_uni presented higher values when compared with MIP_sta and proved to be reproducible in subjects with spontaneous breathing without artificial airway.

Clinical review: intensive care unit acquired weakness

A substantial number of patients admitted to the ICU because of an acute illness, complicated surgery, severe trauma, or burn injury will develop a de novo form of muscle weakness during the ICU stay that is referred to as “intensive care unit acquired weakness” (ICUAW). This ICUAW evoked by critical illness can be due to axonal neuropathy, primary myopathy, or both. Underlying pathophysiological mechanisms comprise microvascular, electrical, metabolic, and bioenergetic alterations, interacting in a complex way and culminating in loss of muscle strength and/or muscle atrophy. ICUAW is typically symmetrical and affects predominantly proximal limb muscles and respiratory muscles, whereas facial and ocular muscles are often spared. The main risk factors for ICUAW include high severity of illness upon admission, sepsis, multiple organ failure, prolonged immobilization, and hyperglycemia, and also older patients have a higher risk. The role of corticosteroids and neuromuscular blocking agents remains unclear. ICUAW is diagnosed in awake and cooperative patients by bedside manual testing of muscle strength and the severity is scored by the Medical Research Council sum score. In cases of atypical clinical presentation or evolution, additional electrophysiological testing may be required for differential diagnosis. The cornerstones of prevention are aggressive treatment of sepsis, early mobilization, preventing hyperglycemia with insulin, and avoiding the use parenteral nutrition during the first week of critical illness. Weak patients clearly have worse acute outcomes and consume more healthcare resources. Recovery usually occurs within weeks or months, although it may be incomplete with weakness persisting up to 2 years after ICU discharge. Prognosis appears compromised when the cause of ICUAW involves critical illness polyneuropathy, whereas isolated critical illness myopathy may have a better prognosis. In addition, ICUAW has shown to contribute to the risk of 1-year mortality. Future research should focus on new preventive and/or therapeutic strategies for this detrimental complication of critical illness and on clarifying how ICUAW contributes to poor longer-term prognosis.

The Sick and the Weak: Neuropathies/Myopathies in the Critically Ill

Critical illness polyneuropathies (CIP) and myopathies (CIM) are common complications of critical illness. Several weakness syndromes are summarized under the term intensive care unit-acquired weakness (ICUAW). We propose a classification of different ICUAW forms (CIM, CIP, sepsis-induced, steroid-denervation myopathy) and pathophysiological mechanisms from clinical and animal model data. Triggers include sepsis, mechanical ventilation, muscle unloading, steroid treatment, or denervation. Some ICUAW forms require stringent diagnostic features; CIM is marked by membrane hypoexcitability, severe atrophy, preferential myosin loss, ultrastructural alterations, and inadequate autophagy activation while myopathies in pure sepsis do not reproduce marked myosin loss. Reduced membrane excitability results from depolarization and ion channel dysfunction. Mitochondrial dysfunction contributes to energy-dependent processes. Ubiquitin proteasome and calpain activation trigger muscle proteolysis and atrophy while protein synthesis is impaired. Myosin loss is more pronounced than actin loss in CIM. Protein quality control is altered by inadequate autophagy. Ca(2+) dysregulation is present through altered Ca(2+) homeostasis. We highlight clinical hallmarks, trigger factors, and potential mechanisms from human studies and animal models that allow separation of risk factors that may trigger distinct mechanisms contributing to weakness. During critical illness, altered inflammatory (cytokines) and metabolic pathways deteriorate muscle function. ICUAW prevention/treatment is limited, e.g., tight glycemic control, delaying nutrition, and early mobilization. Future challenges include identification of primary/secondary events during the time course of critical illness, the interplay between membrane excitability, bioenergetic failure and differential proteolysis, and finding new therapeutic targets by help of tailored animal models.

High prevalence of respiratory muscle weakness in hospitalized acute heart failure elderly patients

INTRODUCTION

Respiratory Muscle Weakness (RMW) has been defined when the maximum inspiratory pressure (MIP) is lower than 70% of the predictive value. The prevalence of RMW in chronic heart failure patients is 30 to 50%. So far there are no studies on the prevalence of RMW in acute heart failure (AHF) patients.

OBJECTIVES

Evaluate the prevalence of RMW in patients admitted because of AHF and the condition of respiratory muscle strength on discharge from the hospital.

METHODS

Sixty-three patients had their MIP measured on two occasions: at the beginning of the hospital stay, after they had reached respiratory, hemodynamic and clinical stability and before discharge from the hospital. The apparatus and technique to measure MIP were adapted because of age-related limitations of the patients. Data on cardiac ejection fraction, ECG, brain natriuretic peptide (BNP) levels and on the use of noninvasive ventilation (NIV) were collected.

RESULTS

The mean age of the 63 patients under study was 75 years. On admission the mean ejection fraction was 33% (95% CI: 31-35) and the BNP hormone median value was 726.5 pg/ml (range: 217 to 2283 pg/ml); 65% of the patients used NIV. The median value of MIP measured after clinical stabilization was -52.7 cmH2O (range: -20 to -120 cmH2O); 76% of the patients had MIP values below 70% of the predictive value. On discharge, after a median hospital stay of 11 days, the median MIP was -53.5 cmH2O (range:-20 to -150 cmH2O); 71% of the patients maintained their MIP values below 70% of the predictive value. The differences found were not statistically significant.

CONCLUSION

Elderly patients admitted with AHF may present a high prevalence of RMW on admission; this condition may be maintained at similar levels on discharge in a large percentage of these patients, even after clinical stabilization of the heart condition.

Muscle wasting and early mobilization in acute respiratory distress syndrome

Survivors of acute respiratory distress syndrome often sustain muscle wasting and functional impairment related to intensive care unit (ICU)-acquired weakness (ICUAW) and this disability may persist for years after ICU discharge. Early diagnosis in cooperative patients by physical examination is recommended to identify patients at risk for weaning failure and to minimize prolongation of risk factors for ICUAW. When possible, early rehabilitation in critically ill patients improves functional outcomes, likely by reducing disuse atrophy. Interventions designed to correct the functional impairment are lacking and further research to delineate the molecular pathways that give rise to ICUAW are needed.

Critical illness polyneuropathy and myopathy: a systematic review

Critical illness polyneuropathy and critical illness myopathy are frequent complications of severe illness that involve sensorimotor axons and skeletal muscles, respectively. Clinically, they manifest as limb and respiratory muscle weakness. Critical illness polyneuropathy/myopathy in isolation or combination increases intensive care unit morbidity via the inability or difficulty in weaning these patients off mechanical ventilation. Many patients continue to suffer from decreased exercise capacity and compromised quality of life for months to years after the acute event. Substantial progress has been made lately in the understanding of the pathophysiology of critical illness polyneuropathy and myopathy. Clinical and ancillary test results should be carefully interpreted to differentiate critical illness polyneuropathy/myopathy from similar weaknesses in this patient population. The present review is aimed at providing the latest knowledge concerning the pathophysiology of critical illness polyneuropathy/myopathy along with relevant clinical, diagnostic, differentiating, and treatment information for this debilitating neurological disease.

Reversible tetraplegia after percutaneous nephrostolithotomy and septic shock: a case of critical illness polyneuropathy and myopathy with acute onset and complete recovery

Background

Critical illness polyneuropathy (CIP) and critical illness myopathy (CIM) are complications causing weakness of respiratory and limb muscles in critically ill patients. As an important differential diagnosis of Guillain-Barré syndrome (GBS), CIP and CIM should be diagnosed with caution, after a complete clinical and laboratory examination. Although not uncommon in ICU, CIP and CIM as severe complications of percutaneous nephrostolithotomy (PNL) have not been documented in literature.

Case presentation

A 48-year-old Chinese woman was referred to our hospital, complaining of occasional pain in the right lower back for one month. Lithiasis was diagnosed by ultrasonographical and radiological examinations on the urinary system. PNL was indicated and performed. The patient developed CIP and CIM on the fourth day after PNL. Early recognition and treatment of the severe complications contributed to a satisfactory recovery of the patient.

Conclusion

This case expands our understanding of the complications of PNL and underscores the importance of differentiating CIP/CIM from GBS in case of such patients developing weakness after the treatment. Clinical characteristics and examination results should be carefully evaluated to make the diagnosis of CIP or CIM. Both anti-septic prophylaxis and control of hyperglycemia might be effective for the prevention of CIP or CIM; aggressive treatment on sepsis and multiple organ failure is considered to be the most effective measure to reduce the incidence of CIP/CIM.

Innovative mobility strategies for the patient with intensive care unit-acquired weakness: a case report

BACKGROUND AND PURPOSE

Although the benefits of early mobilization in the intensive care unit (ICU) have been well documented in recent years, the decision-making process and customization of treatment strategies for patients with ICU-acquired weakness have not been well defined in the literature. This case report will describe a patient with ICU-acquired weakness in the long-term acute care hospital (LTACH) setting and mobilization strategies that include novel devices for therapeutic exercise and gait training.

CASE DESCRIPTION

A 73-year-old, active woman underwent a routine cardioversion for atrial fibrillation but developed multiple complications, including sepsis and respiratory failure. The patient spent 3 weeks of limited activity in the ICU and was transferred to our LTACH for continued medical intervention and rehabilitation. A 4-phase graded mobilization program was initiated in the LTACH ICU. Within that program, the physical therapy interventions included partial weight-bearing antigravity strength training with a mobile leg press and gait training with a hydraulic-assist platform walker.

OUTCOME

Before interventions, the patient had severe weakness (Medical Research Council [MRC] sum score of 18/60) and displayed complete dependence for all functioning. She progressed to being able to ambulate 150 ft (1 ft=0.3048 m) using a rolling walker with accompanying strength increases to an MRC sum score of 52/60.

DISCUSSION

This case report describes novel mobility strategies for managing a patient with ICU-acquired weakness. The application of a graded mobilization program using a mobile leg press and a hydraulic-assist platform walker was safe and feasible, and appeared to expedite the patient's recovery process while decreasing the amount of manual lifting for the therapists.

ICU-based rehabilitation and its appropriate metrics

PURPOSE OF REVIEW

Survival of critically ill patients is frequently associated with significant functional impairment and reduced health-related quality of life. Early rehabilitation of ICU patients has recently been identified as an important focus for interdisciplinary ICU teams. However, the amount of rehabilitation performed in ICUs is often inadequate. The scope of the review is to discuss recent developments in application of assessment tools and rehabilitation in critically ill patients within an interdisciplinary approach.

RECENT FINDINGS

ICU-based rehabilitation has become an important evidence-based component in the management of patients with critical illness. The assessment and evidence-based treatment of these patients should include a focus on prevention and treatment of deconditioning (muscle weakness, joint stiffness, impaired functional performance) and weaning failure (respiratory muscle weakness) to identify targets for rehabilitation. A variety of modalities for assessment and early ICU rehabilitation are supported by emerging clinical research and must be implemented according to the stage of critical illness, comorbidities, and consciousness and cooperation of the patient.

SUMMARY

Daily evaluation of every critically ill patient should include evaluation of the need for bedrest and immobility, and assessment of the potential for early rehabilitation interventions. Early ICU rehabilitation is an interdisciplinary team responsibility, involving physical therapists, occupational therapists, nurses and medical staff.

Neuromuscular electrical stimulation for intensive care unit-acquired weakness: protocol and methodological implications for a randomized, sham-controlled, phase II trial

BACKGROUND

As the population ages and critical care advances, a growing number of survivors of critical illness will be at risk for intensive care unit (ICU)-acquired weakness. Bed rest, which is common in the ICU, causes adverse effects, including muscle weakness. Consequently, patients need ICU-based interventions focused on the muscular system. Although emerging evidence supports the benefits of early rehabilitation during mechanical ventilation, additional therapies may be beneficial. Neuromuscular electrical stimulation (NMES), which can provide some muscular activity even very early during critical illness, is a promising modality for patients in the ICU.

OBJECTIVE

The objectives of this article are to discuss the implications of bed rest for patients with critical illness, summarize recent studies of early rehabilitation and NMES in the ICU, and describe a protocol for a randomized, phase II pilot study of NMES in patients receiving mechanical ventilation.

DESIGN

The study was a randomized, sham-controlled, concealed, phase II pilot study with caregivers and outcome assessors blinded to the treatment allocation.

SETTING

The study setting will be a medical ICU.

PARTICIPANTS

The study participants will be patients who are receiving mechanical ventilation for 1 day or more, who are expected to stay in the ICU for an additional 2 days or more, and who meet no exclusion criteria.

INTERVENTION

The intervention will be NMES (versus a sham [control] intervention) applied to the quadriceps, tibialis anterior, and gastrocnemius muscles for 60 minutes per day.

MEASUREMENTS

Lower-extremity muscle strength at hospital discharge will be the primary outcome measure.

LIMITATIONS

Muscle strength is a surrogate measure, not a patient-centered outcome. The assessments will not include laboratory, genetic, or histological measures aimed at a mechanistic understanding of NMES. The optimal duration or dose of NMES is unclear.

CONCLUSIONS

If NMES is beneficial, the results of the study will help advance research aimed at reducing the burden of muscular weakness and physical disability in survivors of critical illness.

Intensive care unit-acquired weakness: implications for physical therapist management

Patients admitted to the intensive care unit (ICU) can develop a condition referred to as "ICU-acquired weakness." This condition is characterized by profound weakness that is greater than might be expected to result from prolonged bed rest. Intensive care unit-acquired weakness often is accompanied by dysfunction of multiple organ systems. Individuals with ICU-acquired weakness typically have significant activity limitations, often requiring physical assistance for even the most basic activities associated with bed mobility. Many of these individuals have activity limitations months to years after hospitalization. The purpose of this article is to review evidence that guides physical rehabilitation of people with ICU-acquired weakness. Included are diagnostic criteria, medical management, and prognostic indicators, as well as criteria for beginning physical rehabilitation, with an emphasis on patient safety. Data are presented indicating that rehabilitation can be implemented with very few adverse effects. Evidence is provided for appropriate measurement approaches and for physical intervention strategies. Finally, some of the key issues are summarized that should be investigated to determine the best intervention guidelines for individuals with ICU-acquired weakness.