Silicone-ring Roux-en-Y gastric bypass in the treatment of obesity: effects of laparoscopic versus laparotomic surgery on respiration

Obesity-related reduced spirometry and altered breathing pattern are associated with mechanical disadvantage of the diaphragm

The aim of this study was to characterize the breathing patterns of individuals with obesity during routine activities such as sitting and standing, and to identify potential contributors to alterations in these patterns. Measurements performed in 20 male subjects with obesity (BMI, 31.8±1.5 kg/m2) and 20 controls (BMI, 23.5±1.4 kg/m2) included anthropometric parameters, breathing-patterns in sitting and standing positions, spirometry, maximal respiratory pressures, and diaphragm B-mode ultrasonography. Individuals with obesity exhibited lower tidal volume and increased respiratory rate to maintain a similar minute-ventilation (p<0.05). Subjects with obesity demonstrated impaired spirometry and respiratory muscle strength, with inspiratory functions being notably compromised (p<0.05). Individuals with obesity had a greater diaphragm thickness at end inspiration but lower thickening-fraction at end quiet and forced breathings and reduced diaphragmatic displacement and excursion during maximal breaths (p<0.05). BMI was negatively associated with all respiratory function markers (p<0.05). Individuals with obesity exhibit a higher respiratory rate but lower tidal volume, likely to accommodate decreased compliance and excess thoracic and abdominal fat, further hindering inspiratory function. Moreover, increased adiposity is associated with a thicker but weaker diaphragm, primarily due to the diaphragm's mechanical disadvantage rather than its intrinsic inability to generate force.

Comparison of respiratory muscle strength through manovacuometry in the early postoperative period of bariatric surgery by laparotomy and laparoscopy

INTRODUCTION

surgical treatment of obesity causes important changes in respiratory mechanics.

AIM

Comparatively analyze respiratory muscle strength in post bariatric patients underwent to gastric bypass by laparotomy and laparoscopy during hospital stay.

METHODS

observational study with a non-randomized longitudinal design, of a quantitative character. Data were collected from 60 patients with BMI 40Kg/m2, divided in laparotomy group (n=30) and laparoscopy group (n=30). Smokers, patients with previous lung diseases and those unable to perform the exam correctly were excluded. Both groups were evaluated at immediate postoperative, first and second postoperative days with manovacuometry for respiratory muscle strength and visual analogue pain scale.

RESULTS

the sample was homogeneous in age, sex and BMI. Reduction in maximal respiratory pressures was observed after surgery for those operated on by laparotomy, no return to baseline values on discharge day on the second postoperative day. This group had also more severe pain and longer operative time. There was no difference in respiratory pressure measurements after surgery in the laparoscopy group.

CONCLUSION

conventional bariatric surgery reduces muscle strength in the postoperative period and leads to more intense pain during hospitalization when compared to the laparoscopy group.

Comparação da força muscular respiratória através da manovacuometria no pós-operatório precoce de cirurgia bariátrica por laparotomia e por videolaparoscopia

RESUMO Introdução: o tratamento cirúrgico da obesidade acarreta importantes alterações na mecânica respiratória. Objetivo: analisar comparativamente a força muscular respiratória em pacientes submetidos à cirurgia bariátrica do tipo bypass gástrico por laparotomia e por videolaparoscopia durante o internamento cirúrgico. Métodos: estudo observacional com delineamento longitudinal não-randomizado, de caráter quantitativo. Foram coletados dados de 60 pacientes com índice de massa corporal igual ou superior a 40Kg/m2, candidatos a cirurgia bariátrica e divididos em grupo 1, para os operados por laparotomia (n=30), e grupo 2, para os operados por videolaparoscopia (n=30). Foram excluídos os tabagistas, os pacientes incapazes de executar o exame de forma correta e os portadores de doenças pulmonares prévias. Ambos os grupos foram avaliados no pré-operatório imediato, no primeiro e no segundo dias de pós-operatório através do teste de manovacuometria para a força muscular respiratória e da escala visual analógica de dor. Resultados: a amostra foi homogênea em relação à idade, índice de massa corporal e sexo. Foi observado redução das pressões respiratórias máximas após a cirurgia para os operados por laparotomia, sem retorno aos valores basais no dia da alta hospitalar no segundo dia pósoperatório. Esse grupo também cursou com dor mais intensa e maior tempo cirúrgico. Não houve diferença das medidas de pressão respiratória após a cirurgia no grupo operado por laparoscopia. Conclusões: a cirurgia bariátrica pela via convencional reduz a força muscular respiratória no pós-operatório e cursa com dor mais intensa durante a internação cirúrgica em relação à via laparoscópica.

Impact of weight reduction surgery on static and dynamic lung volumes

BACKGROUND

Obesity could affect many functions of the body systems, particularly respiratory system. Effect of obesity on respiratory system leads to an impairment in pulmonary function tests which is represented by a decrease in lung volumes and capacities, therefore obstructive or restrictive pulmonary diseases may develop. The recent study was conducted to investigate and assess the impact of weight loss by surgery on static and dynamic lung volumes (pulmonary function tests) and the improvement in co morbidities.

PATIENTS AND METHODS

The study included 68 morbid obese patients, 36 females and 32 males. The patients were with age range 24-56 years, BMI≥ 40 kg/m2or≥35 kg/m2 with co morbidities. Pulmonary volumes and function tests of all patients were measured before weight loss surgery and one year after the surgery.

RESULT

The results showed a significant reduction in the body weight (p < 0.05), with an improvement in co morbidities. Pulmonary volumes ERV,IRV,TLC, FRC and RV were significantly changed one year after surgery as well as there were significant increases in the mean values of the dynamic volumes such as FEV1,FEV1%,FEF50%, PEF and MVV.(p < 0.05).

CONCLUSION

loss of excess body weight by bariatric surgery resulted in a significant improvement in co morbidities and function of respiratory system represented by significant changes in both static and dynamic lung volumes ….

Analysis of the prevalence of atelectasis in patients undergoing bariatric surgery

BACKGROUND AND OBJECTIVE

To observe the prevalence of atelectasis in patients undergoing bariatric surgery and the influence of the body mass index (BMI), gender and age on the prevalence of atelectasis.

METHOD

Retrospective study of 407 patients and reports on chest X-rays carried out before and after bariatric surgery over a period of 14 months. Only patients who underwent bariatric surgery by laparotomy were included.

RESULTS

There was an overall prevalence of 37.84% of atelectasis, with the highest prevalence in the lung bases and with greater prevalence in women (RR=1.48). There was a ratio of 30% for the influence of age for individuals under the age of 36, and of 45% for those older than 36 (RR=0.68). There was no significant influence of BMI on the prevalence of atelectasis.

CONCLUSION

The prevalence of atelectasis in bariatric surgery is 37% and the main risk factors are being female and aged over 36 years.

Primary banded Roux-en-Y gastric bypass: a systematic review

Primary banding of Roux-en-Y gastric bypass remains controversial. Though there are surgeons who believe it should be the standard practice as it results in superior weight loss and prevents weight regain in the long term, there are others who are concerned about the risk of food intolerance and complications related to band. This review investigates published English language literature systematically to find out the advantages and disadvantages of primary banding of a Roux-en-Y gastric bypass.

Use of positive pressure in the bariatric surgery and effects on pulmonary function and prevalence of atelectasis: randomized and blinded clinical trial

Background

In surgical procedures, obesity is a risk factor for the onset of intra and postoperative respiratory complications.

Aim

Determine what moment of application of positive pressure brings better benefits on lung function, incidence of atelectasis and diaphragmatic excursion, in the preoperative, intraoperative or immediate postoperative period.

Method

Randomized, controlled, blinded study, conducted in a hospital and included subjects with BMI between 40 and 55 kg/m², 25 and 55 years, underwent bariatric surgery by laparotomy. They were underwent preoperative and postoperative evaluations. They were allocated into four different groups: 1) Gpre: treated with positive pressure in the BiPAP mode (Bi-Level Positive Airway Pressure) before surgery for one hour; 2) Gpos: BIPAP after surgery for one hour; 3) Gintra: PEEP (Positive End Expiratory Pressure) at 10 cmH₂O during the surgery; 4) Gcontrol: only conventional respiratory physiotherapy. The evaluation consisted of anthropometric data, pulmonary function tests and chest radiography.

Results

Were allocated 40 patients, 10 in each group. There were significant differences for the expiratory reserve volume and percentage of the predicted expiratory reserve volume, in which the groups that received treatment showed a smaller loss in expiratory reserve volume from the preoperative to postoperative stages. The postoperative radiographic analysis showed a 25% prevalence of atelectasis for Gcontrol, 11.1% for Gintra, 10% for Gpre, and 0% for Gpos. There was no significant difference in diaphragmatic mobility amongst the groups.

Conclusion

The optimal time of application of positive pressure is in the immediate postoperative period, immediately after extubation, because it reduces the incidence of atelectasis and there is reduction of loss of expiratory reserve volume.

Effects of bariatric surgery on inspiratory muscle strength

Background

The respiratory function is affected by obesity due to an increased deposition of fat on the chest wall. The objective of this study was to investigate the strength of the inspiratory respiratory muscles of obese individuals and the possible influence of bariatric surgery on it by measuring the maximum inspiratory pressure (MIP).

Methods

Patients referred to a bariatric centre between the 3rd of October 2011 and the 3rd of May 2012 were screened preoperatively by a multidisciplinary team. Their MIP was measured at screening and 3, 6 and 9 months postoperative. In case of a preoperative MIP lower than 70% of predicted pressure training was provided supervised by a physiotherapist.

Results

The mean age of 124 included patients was 42.9 ± 11.0 years and mean BMI was 43.1 ± 5.2 kg/m². The mean predicted MIP preoperatively was 127 ± 31 in cm H₂O and the mean measured MIP was 102 ± 24 in cm H₂O. Three patients (2.4%) received training. Three months after surgery the MIP was 76 ± 26 cm H₂O, after 6 months 82 ± 28 cm H₂O and after 9 months 86 ± 28 cm H₂O. All postoperative measurements were significant lower than preoperatively (P < 0.05). The only influencing factor for the preoperative MIP was age (p = 0.014).

Conclusion

The preoperative MIP values were significantly lower than the predicted MIP values, probably due to altered respiratory mechanics.

Laparoscopic versus open obesity surgery: a meta-analysis of pulmonary complications

The clinical effects of laparoscopy in the pulmonary function of obese patients have been poorly investigated in the past. A systematic review was undertaken, with the objective to identify published evidence on pulmonary complications in laparoscopic surgery in the obese. Outcome measures included pulmonary morbidity, pulmonary infection and mortality. The random effects model was used to calculate combined overall effect sizes of pooled data. Data are presented as the odds ratio (OR) with 95% confidence interval (CI). A total of 6 randomized and 14 observational studies were included, which reported data on 185,328 patients. Pulmonary complications occurred in 1.6% of laparoscopic and in 3.6% of open procedures (OR 0.45, 95% CI 0.34-0.60). Pneumonia was reported in 0.5% and in 1.1%, respectively (OR 0.45, 95% CI 0.40-0.51). Available evidence suggests lower pulmonary morbidity for laparoscopic surgery in obese patients; further quality studies are however necessary to consolidate these findings.

WGA-Alexa transsynaptic labeling in the phrenic motor system of adult rats: Intrapleural injection versus intradiaphragmatic injection

BACKGROUND

Intrapleural injection of CTB-Alexa 488, a retrograde tracer, provides an alternative labeling technique to the surgically invasive laparotomy required for intradiaphragmatic injection. However, CTB-Alexa 488 is incapable of crossing synapses restricting the tracer to the phrenic nuclei and the intercostal motor nuclei in the spinal cord.

NEW METHOD

Intrapleural injection of WGA-Alexa 488, a transsynaptic tracer, provides a method to label the respiratory motor pathway in both the spinal cord and medulla. Intradiaphragmatic injection of WGA-Alexa 594 and vagal nerve injections of True blue were used to confirm the phrenic nuclei and to differentiate between the rVRG and the NA in the medulla.

RESULTS

Following intrapleural injection, WGA-Alexa 488 was retrogradely transported to the phrenic nuclei and to the intercostal motor nuclei. Subsequently WGA-Alexa 488 was transsynaptically transported from the phrenic motoneurons to the pre-motor neurons in the rVRG that provide the descending drive to the phrenic neurons during inspiration. In addition WGA-Alexa 488 was identified in select cells of the NA confirmed by a dual label of both WGA-Alexa 488 and True blue.

COMPARISON WITH EXISTING METHOD

WGA-Alexa 488 demonstrates retrograde transsynaptic labeling following intrapleural injection whereas the previous method of injecting CTB-Alexa 488 only demonstrates retrograde labeling.

CONCLUSIONS

Intrapleural injection of WGA-Alexa fluor conjugates is an effective method to transsynaptically label the phrenic motor system providing an alternative for the invasive laparotomy required for intradiaphragmatic injections. Furthermore, the study provides the first anatomical evidence of a direct synaptic relationship between rVRG and select NA cells.

Injection of WGA-Alexa 488 into the ipsilateral hemidiaphragm of acutely and chronically C2 hemisected rats reveals activity-dependent synaptic plasticity in the respiratory motor pathways

WGA-Alexa 488 is a fluorescent neuronal tracer that demonstrates transsynaptic transport in the central nervous system. The transsynaptic transport occurs over physiologically active synaptic connections rather than less active or silent connections. Immediately following C2 spinal cord hemisection (C2Hx), when WGA-Alexa 488 is injected into the ipsilateral hemidiaphragm, the tracer diffuses across the midline of the diaphragm and retrogradely labels the phrenic nuclei (PN) bilaterally in the spinal cord. Subsequently, the tracer is transsynaptically transported bilaterally to the rostral Ventral Respiratory Groups (rVRGs) in the medulla over physiologically active connections. No other neurons are labeled in the acute C2Hx model at the level of the phrenic nuclei or in the medulla. However, with a recovery period of at least 7weeks (chronic C2Hx), the pattern of WGA-Alexa 488 labeling is notably changed. In addition to the bilateral PN and rVRG labeling, the chronic C2Hx model reveals fluorescence in the ipsilateral ventral and dorsal spinocerebellar tracts, and the ipsilateral reticulospinal tract. Furthermore, interneurons are labeled bilaterally in laminae VII and VIII of the spinal cord as well as neurons in the motor nuclei bilaterally of the intercostal and forelimb muscles. Moreover, in the chronic C2Hx model, there is bilateral labeling of additional medullary centers including raphe, hypoglossal, spinal trigeminal, parvicellular reticular, gigantocellular reticular, and intermediate reticular nuclei. The selective WGA-Alexa 488 labeling of additional locations in the chronic C2Hx model is presumably due to a hyperactive state of the synaptic pathways and nuclei previously shown to connect with the respiratory centers in a non-injured model. The present study suggests that hyperactivity not only occurs in neuronal centers and pathways caudal to spinal cord injury, but in supraspinal centers as well. The significance of such injury-induced plasticity is that hyperactivity may be a mechanism to re-establish lost function by compensatory routes which were initially physiologically inactive.

I. Aplicação da pressão positiva contínua nas vias aéreas em pacientes em pós-operatório de cirurgia bariátrica

O objetivo deste trabalho foi avaliar o efeito da aplicação da pressão positiva contínua nas vias aéreas (CPAP), na frequência respiratória (FR), no volume corrente (VC) e no volume minuto (VM), em pacientes em pós-operatório de cirurgia bariátrica. Foram estudadas dez pacientes com média de idade 29,8±8 anos, classificadas como obesas mórbidas [índice de massa corpórea (IMC) de 47,5±7,2 kg/m²] que receberam CPAP de 8 a 10 cmH2O, por 30 minutos, uma vez ao dia, durante dois dias consecutivos, no pós-operatório de cirurgia bariátrica. Antes e após a aplicação da CPAP, foram aferidos a FR e o VM por meio do ventilômetro e, de forma indireta, foi calculado o VC. Para verificar a normalidade dos dados foi aplicado o teste de Shapiro-Wilk, e, após, as medidas foram comparadas com o uso do Teste t de Student e de Man-Whitney. As análises foram processadas com o uso do SPSS 7,5 considerando o nível de 5% de significância. Houve um aumento significativo para as seguintes variáveis estudadas no primeiro e no segundo dia de aplicação: FR=20±6 resp/min versus 26±7 resp/min (p=0,009) e FR=22±7 resp/min versus 26±8 resp/min (p=0,007); VM=9,57±2,75 L versus 12,39±4,18 L (p=0,041) e VM=9,71±2,52 L versus 11,18±2,96 L (p=0,037). Os valores do VC=360±157,59 mL versus 440±69,18 mL (p=0,21) e 401±90,46 mL versus 416±78,04 mL (p=0,18) não apresentaram diferença significativa na comparação pré- e pós-aplicação, nos dois dias de terapia. Assim, foi possível concluir que a CPAP pode ser aplicada como recurso auxiliar da fisioterapia respiratória no tratamento de pacientes em período pós-operatório de cirurgia bariátrica, para a manutenção do VC, porém atenção deve ser tomada durante a aplicação, pois pode haver aumento da FR.

Effects of preoperative inspiratory muscle training in obese women undergoing open bariatric surgery: respiratory muscle strength, lung volumes, and diaphragmatic excursion

OBJECTIVE

To determine whether preoperative inspiratory muscle training is able to attenuate the impact of surgical trauma on the respiratory muscle strength, in the lung volumes, and diaphragmatic excursion in obese women undergoing open bariatric surgery.

DESIGN

Randomized controlled trial.

SETTING

Meridional Hospital, Cariacica/ES, Brazil.

SUBJECTS

Thirty-two obese women undergoing elective open bariatric surgery were randomly assigned to receive preoperative inspiratory muscle training (inspiratory muscle training group) or usual care (control group).

MAIN MEASURES

Respiratory muscle strength (maximal static respiratory pressure--maximal inspiratory pressure and maximal expiratory pressure), lung volumes, and diaphragmatic excursion.

RESULTS

After training, there was a significant increase only in the maximal inspiratory pressure in the inspiratory muscle training group. The maximal expiratory pressure, the lung volumes and the diaphragmatic excursion did not show any significant change with training. In the postoperative period there was a significant decrease in maximal inspiratory pressure in both the groups. However, there was a decrease of 28% in the inspiratory muscle training group, whereas it was 47% in the control group. The decrease in maximal expiratory pressure and in lung volumes in the postoperative period was similar between the groups. There was a significant reduction in the measures of diaphragmatic excursion in both the groups.

CONCLUSION

The preoperative inspiratory muscle training increased the inspiratory muscle strength (maximal inspiratory pressure) and attenuated the negative postoperative effects of open bariatric surgery in obese women for this variable, though not influencing the lung volumes and the diaphragmatic excursion.