The abdominal muscles in anaesthesia and after surgery

Physiotherapy Regimens in Esophagectomy and Gastrectomy: a Systematic Review and Meta-Analysis

Background

Esophageal and gastric cancer surgery are associated with considerable morbidity, specifically postoperative pulmonary complications (PPCs), potentially accentuated by underlying challenges with malnutrition and cachexia affecting respiratory muscle mass. Physiotherapy regimens aim to increase the respiratory muscle strength and may prevent postoperative morbidity.

Objective

The aim of this study was to assess the impact of physiotherapy regimens in patients treated with esophagectomy or gastrectomy.

Methods

An electronic database search was performed in the MEDLINE, EMBASE, CENTRAL, CINAHL and Pedro databases. A meta-analysis was performed to assess the impact of physiotherapy on the functional capacity, incidence of PPCs and postoperative morbidity, in-hospital mortality rate, length of hospital stay (LOS) and health-related quality of life (HRQoL).

Results

Seven randomized controlled trials (RCTs) and seven cohort studies assessing prehabilitation totaling 960 patients, and five RCTs and five cohort studies assessing peri- or postoperative physiotherapy with 703 total patients, were included. Prehabilitation resulted in a lower incidence of postoperative pneumonia and morbidity (Clavien–Dindo score ≥ II). No difference was observed in functional exercise capacity and in-hospital mortality following prehabilitation. Meanwhile, peri- or postoperative rehabilitation resulted in a lower incidence of pneumonia, shorter LOS, and better HRQoL scores for dyspnea and physical functioning, while no differences were found for the QoL summary score, global health status, fatigue, and pain scores.

Conclusion

This meta-analysis suggests that implementing an exercise intervention may be beneficial in both the preoperative and peri- or postoperative periods. Further investigation is needed to understand the mechanism through which exercise interventions improve clinical outcomes and which patient subgroup will gain the maximal benefit.

Supplementary Information

The online version contains supplementary material available at 10.1245/s10434-021-11122-7.

Differential Effects of Intraoperative Positive End-expiratory Pressure (PEEP) on Respiratory Outcome in Major Abdominal Surgery Versus Craniotomy

OBJECTIVES

In this study, we examined whether (1) positive end-expiratory pressure (PEEP) has a protective effect on the risk of major postoperative respiratory complications in a cohort of patients undergoing major abdominal surgeries and craniotomies, and (2) the effect of PEEP is differed by surgery type.

BACKGROUND

Protective mechanical ventilation with lower tidal volumes and PEEP reduces compounded postoperative complications after abdominal surgery. However, data regarding the use of intraoperative PEEP is conflicting.

METHODS

In this observational study, we included 5915 major abdominal surgery patients and 5063 craniotomy patients. Analysis was performed using multivariable logistic regression. The primary outcome was a composite of major postoperative respiratory complications (respiratory failure, reintubation, pulmonary edema, and pneumonia) within 3 days of surgery.

RESULTS

Within the entire study population (major abdominal surgeries and craniotomies), we found an association between application of PEEP ≥5 cmH2O and a decreased risk of postoperative respiratory complications compared with PEEP <5 cmH2O. Application of PEEP >5 cmH2O was associated with a significant lower odds of respiratory complications in patients undergoing major abdominal surgery (odds ratio 0.53, 95% confidence interval 0.39 - 0.72), effects that translated to deceased hospital length of stay [median hospital length of stay : 6 days (4-9 days), incidence rate ratios for each additional day: 0.91 (0.84 - 0.98)], whereas PEEP >5 cmH2O was not significantly associated with reduced odds of respiratory complications or hospital length of stay in patients undergoing craniotomy.

CONCLUSIONS

The protective effects of PEEP are procedure specific with meaningful effects observed in patients undergoing major abdominal surgery. Our data suggest that default mechanical ventilator settings should include PEEP of 5-10 cmH2O during major abdominal surgery.

Optimizing working space in laparoscopy: CT-measurement of the effect of neuromuscular blockade and its reversal in a porcine model

OBJECTIVE

The objective of this paper was to determine the effect of neuromuscular blockade (NMB) on working space in a porcine laparoscopy model.

BACKGROUND

Conflicting results on the effect of NMB on laparoscopic working space are found in literature. Almost all studies are limited by absence of objective assessment of working space or use surrogate outcomes.

METHODS

In a standardized porcine laparoscopy model, laparoscopic working-space dimensions with and without NMB were investigated in 16 animals using computed tomography at intra-abdominal pressures of 0, 5, 10, and 15 mmHg during multiple runs of abdominal insufflation.

RESULTS

No statistically significant effect of NMB on abdominal dimensions and laparoscopic working-space volume was found during CO2 pneumoperitoneum. In contrast, the effect of pre-stretching of the abdominal wall by a previous abdominal insufflation was found to be significant.

CONCLUSIONS

This experimental study confirms the results from several clinical studies that NMB does not influence laparoscopic working space. Studies dealing with working space during laparoscopy should take note of pre-stretching bias.

Effects of anesthetics, sedatives, and opioids on ventilatory control

This article provides a comprehensive, up to date summary of the effects of volatile, gaseous, and intravenous anesthetics and opioid agonists on ventilatory control. Emphasis is placed on data from human studies. Further mechanistic insights are provided by in vivo and in vitro data from other mammalian species. The focus is on the effects of clinically relevant agonist concentrations and studies using pharmacological, that is, supraclinical agonist concentrations are de-emphasized or excluded.

Redes bayesianas para eleição da ventilação mecânica no pós-operatório de cirurgia cardíaca

INTRODUÇÃO: A ventilação mecânica no pós-operatório de cirurgia cardíaca pode trazer algumas complicações respiratórias ao paciente. Para minimizar esse risco é necessária a adaptação correta e rápida do ventilador mecânico. A dificuldade para isso está no número expressivo de variáveis para a regulagem do ventilador mecânico e na obtenção de todas essas variáveis. Como o período de ventilação mecânica geralmente não ultrapassa 12 horas, esse tempo deve ser otimizado para que o paciente possa estar em ventilação espontânea o mais rapidamente possível. OBJETIVOS: Este trabalho propõe o uso de redes bayesianas (RB) para auxiliar o profissional no momento da decisão, agilizando o atendimento dos pacientes. MATERIAIS E MÉTODOS: Para o desenvolvimento da RB fez-se necessário o uso de uma base de dados com casos clínicos, a qual se constituiu de 137 casos. A avaliação foi realizada por meio das medidas de validade operacionais de instrumentos, tabelas de contingência e curvas ROC. RESULTADOS: Mostraram que a RB desenvolvida apresentou um adequado desempenho para a eleição da modalidade e parâmetros ventilatórios. CONCLUSÃO: Os resultados com a RB foram semelhantes aos indicados pela literatura, mostrando assim uma compatibilidade entre o raciocínio humano e o computacional.

Endovascular treatment of abdominal aortic aneurysm after previous left pneumonectomy: a sound choice

Surgical treatment of abdominal aortic aneurysm after previous pneumonectomy is a challenge because of the impaired respiratory function and increased surgical risks. Endovascular aneurysm repair in anatomically suited high-surgical-risk patients offers excellent short-term results and provides good protection from aneurysm-related death. In this article, we report a successful endovascular aneurysm repair of an infrarenal aortic aneurysm in a patient with past left pneumonectomy.

Preoperative Assessment for Obstructive Sleep Apnoea and the Prediction of Postoperative Respiratory Obstruction and Hypoxaemia

Patients scheduled for elective surgery requiring general anaesthesia and hospital admission were assessed for risk of obstructive sleep apnoea (OSA) using history, body mass index and upper airway examination to determine any relation between OSA risk and the rate of respiratory events after surgery. Anaesthesia and postoperative analgesia were at the discretion of the treating anaesthetist, who was made aware of any suspicion of OSA. Respiratory monitoring for apnoeas (central or obstructive), hypopnoeas and oxygen desaturations was continuous for a 12-hour period on the first postoperative night. We used automated analysis and visual scanning of respiratory recordings, but sleep stages were not assessed. Patients classified as OSA risk had more respiratory obstructive events per hour than controls (38±22 vs. 14±10) and an increased proportion of the 12-hour monitored period with oxygen saturation <90% (7±12% vs. 2±5% of the 12-hour period). Perioperative morphine dose was predictive of central apnoeas for both OSA risk and control patients (P=0.002). This study suggests that preoperative suspicion of OSA should lead to increased postoperative monitoring and efforts to minimise sedation and opioid dose. It also supports the routine use of supplemental oxygen with patient-controlled opioid analgesia.

Fentanyl decreases end-expiratory lung volume in patients anaesthetized with sevoflurane

BACKGROUND

In patients breathing spontaneously during anaesthesia, expiratory muscle activity can be a prominent feature. This activity is triggered or exaggerated by opioid administration, which causes a prompt increase in intra-abdominal pressure. The effect of this increased expiratory activity on end-expiratory lung volume is not described.

METHODS

Nine patients having minor gynaecological procedures were studied during stable anaesthetic conditions, breathing sevoflurane (end tidal 2.6%) through a laryngeal mask airway, in a circle system. The spill valve was closed and the fresh gas flow was temporarily reduced to approximate the oxygen uptake. The volume of the reservoir bag was then measured by placing it in a hinged, wedge-shaped container. Fentanyl (0.5 microg kg(-1) ideal body weight) was given after 1 min of stable recording, and the change in end-expiratory volume measured after 3 min.

RESULTS

End-expiratory lung volume decreased in all patients by 160 (111) ml (mean, SD) (P<0.01). The decrease did not relate to obesity.

CONCLUSIONS

During sevoflurane anaesthesia, fentanyl causes a rapid reduction in functional residual capacity. This is caused by increased activity of expiratory muscles and an increase in intra-abdominal pressure.

Respiratory muscle activity and respiratory obstruction after abdominal surgery

BACKGROUND

Respiratory movements in patients after abdominal surgery are frequently abnormal, with associated disturbances in the pattern of inspiratory pressure generation. The reasons for these abnormalities are not clear and have been attributed to impaired action of the diaphragm. However, an alternative is that partial airway obstruction could trigger reflex activation of the inspiratory ribcage muscles, which would cause a similar pattern of inspiratory pressure change. Direct measurement of electrical activity can indicate if reflex activation of inspiratory muscles occurs when partial airway obstruction is present.

METHODS

In an open study, we implanted electrodes to measure the EMG of scalene, intercostal and external oblique abdominal muscles in patients after lower abdominal surgery. Analgesia was with morphine i.v. by patient control. We used nasal cannulae to measure nasal airflow and compared EMG activity when airway obstruction was present with activity when breathing was not obstructed.

RESULTS

The pattern of activity of the different muscles was distinct. Intercostal activity reached a maximum during inspiration, before the scalene muscles, whereas scalene activity increased in phase with increasing lung volume. Abdominal muscle activity commenced when expiratory flow had ceased and continued until the next inspiration. In all three muscle groups, partial airway obstruction did not alter muscle activity.

CONCLUSIONS

Partial airway obstruction does not activate inspiratory ribcage muscles, in patients receiving morphine for postoperative analgesia after lower abdominal surgery. Changes in respiratory pressures and abnormalities of chest wall movement described in previous studies cannot be attributed to reflex responses and probably result from increased airway resistance and abdominal muscle action.

Distinct rhythm generators for inspiration and expiration in the juvenile rat

Inspiration and active expiration are commonly viewed as antagonistic phases of a unitary oscillator that generates respiratory rhythm. This view conflicts with observations we report here in juvenile rats, where by administration of fentanyl, a selective mu-opiate agonist, and induction of lung reflexes, we separately manipulated the frequency of inspirations and expirations. Moreover, completely transecting the brainstem at the caudal end of the facial nucleus abolished active expirations, while rhythmic inspirations continued. We hypothesize that inspiration and expiration are generated by coupled, anatomically separate rhythm generators, one generating active expiration located close to the facial nucleus in the region of the retrotrapezoid nucleus/parafacial respiratory group, the other generating inspiration located more caudally in the preBötzinger Complex.

Perioperative lower limb venous haemodynamics in patients under general anaesthesia †

BACKGROUND

This study prospectively determined the haemodynamic changes in the lower limb venous circulation during and shortly after elective abdominal surgery, performed under general anaesthesia.

METHODS

Ten females, aged 36-65 yr, ASA I or II, undergoing total abdominal hysterectomy had their peak, mean and minimum velocities, diameter, volume flow and venous pulsatility (peak-minimum/mean velocity) measured in the left popliteal vein on recumbency with duplex at: (i) baseline, (ii) 15 min after induction, (iii) during surgery, and (iv) in recovery 30 min after extubation. Anaesthesia was induced with fentanyl and propofol, paralysis with vecuronium, maintenance with isoflurane in nitrous oxide 66%, and analgesia with morphine. Results are presented as percentage difference from baseline mean value. The Friedman and Wilcoxon([corrected(*)]) tests were applied.

RESULTS

Mean velocity decreased by 23.6% during surgery and by 34.6% in recovery (P<0.05(*)). Minimum velocity was decreased by 56% during surgery and by 78% in recovery (P<0.05). The volume flow decreased by 26% during surgery, and by 54.4% in recovery (P<0.001). Diameter and peak velocity changed little at surgery and recovery (P>0.2). In contrast, the pulsatility increased by 30% on induction, 83% on surgery and 109% in recovery (P<0.05). Compared with baseline, haemodynamic changes on induction were small (P>0.1(*)).

CONCLUSIONS

A significant decrease in the volume flow, mean and minimum velocities was noted during and immediately after elective total abdominal hysterectomy under general anaesthesia in ASA I and II patients. Flow changes in early recovery mirrored or enhanced those noted intraoperatively. Despite venous flow attenuation, haemodynamic readjustments produced a significant and progressive enhancement of venous flow pulsatility during the course of the procedure.