Impact of spinal anaesthesia on peri-operative lung volumes in obese and morbidly obese female patients*

Reduction in FEV1 following spinal anesthesia is associated with intraoperative complications: A prospective study

Background and Aims

Although Spinal Anesthesia (SA) remains the technique of choice for many surgeries below the umbilicus, it is associated with multiple intraoperative complications. Sympathetic blockade and Bezold-Jarisch reflex do not fully explain SA-related cardiopulmonary complications. Reduction in FEV1 has been reported as a predictor of sudden cardiac death. This study aimed to determine the association between reduction in FEV1 following SA and adverse intraoperative cardiopulmonary complications.

Materials and Methods

A prospective study of 48 patients of ASA status I and II with no history of primary cardiopulmonary disease scheduled for elective surgery under SA. Spirometry was performed based on ATS/ERS guidelines before induction and 30 min after induction of SA. FEV1% predicted was determined using GLI 2012 equations. Participants were grouped into two (∆FEV1% < 10% and ∆FEV1% ≥ 10%) based on reductions (∆) in FEV1% predicted following SA. Logistic regression analyses were used to examine associations between ∆FEV1% and intraoperative hypoxia, hypotension, bradycardia, and nausea/vomiting, with adjustments for age, gender, and BMI.

Results

The mean FEV1% predicted following SA was lower than the mean FEV1% predicted before SA (83.42 vs. 95.31, p = 0.001). In a fully adjusted model, ∆FEV1% ≥ 10% was associated with an increased risk of hypoxia [AOR 13.55; 95% CI, 1.07-171.24, p = 0.044]. The positive associations between ∆FEV1% ≥ 10% and hypotension [2.02 (0.33-12.46), 0.449], bradycardia [1.10 (0.28-4.25), 0.895] and nausea/vomiting [9.74 (0.52-183.94), 0.129] were not statistically significant.

Conclusion

Reduction in FEV1% predicted following SA was associated with adverse intraoperative outcomes. FEV1 may play an important role in the association between SA and cardiopulmonary complications.

Preoperative Atelectasis in Patients with Obesity Undergoing Bariatric Surgery: A Cross-Sectional Study

BACKGROUND

Pulmonary atelectasis is present even before surgery in patients with obesity. We aimed to estimate the prevalence and extension of preoperative atelectasis in patients with obesity undergoing bariatric surgery and to determine if variation in preoperative Spo2 values in the seated position at room air is explained by the extent of atelectasis coverage in the supine position.

METHODS

This was a cross-sectional study in a single center specialized in laparoscopic bariatric surgery. Preoperative chest computed tomographies were reassessed by a senior radiologist to quantify the extent of atelectasis coverage as a percentage of total lung volume. Patients were classified as having atelectasis when the affection was ≥2.5%, to estimate the prevalence of atelectasis. Crude and adjusted prevalence ratios (aPRs) and odds ratios (aORs) were obtained to assess the relative prevalence of atelectasis and percentage coverage, respectively, with increasing obesity category. Inverse probability weighting was used to assess the total, direct (not mediated), and indirect (mediated through atelectasis) effects of body mass index (BMI) on preoperative Spo2, and to quantify the magnitude of mediation (proportion mediated). E-values were calculated, to represent the minimum magnitude of association that an unmeasured confounder with the same directionality of the effect should have to drive the observed point estimates or lower confidence intervals (CIs) to 1, respectively.

RESULTS

In 236 patients with a median BMI of 40.3 kg/m2 (interquartile range [IQR], 34.6-46.0, range: 30.0-77.3), the overall prevalence of atelectasis was 32.6% (95% CI, 27.0-38.9) and by BMI category: 30 to 35 kg/m2, 12.7% (95% CI, 6.1-24.4); 35 to 40 kg/m2, 28.3% (95% CI, 17.2-42.6); 40 to 45 kg/m2, 12.3% (95% CI, 5.5-24.3); 45 to 50 kg/m2, 48.4% (95% CI, 30.6-66.6); and ≥50 units, 100% (95% CI, 86.7-100). Compared to the 30 to 35 kg/m2 group, only the categories with BMI ≥45 kg/m2 had significantly higher relative prevalence of atelectasis-45 to 50 kg/m2, aPR = 3.52 (95% CI, 1.63-7.61, E-value lower bound: 2.64) and ≥50 kg/m2, aPR = 8.0 (95% CI, 4.22-15.2, E-value lower bound: 7.91)-and higher odds of greater atelectasis percentage coverage: 45-50 kg/m2, aOR = 7.5 (95% CI, 2.7-20.9) and ≥50 kg/m2, aOR = 91.5 (95% CI, 30.0-279.3). Atelectasis percent alone explained 70.2% of the variation in preoperative Spo2. The proportion of the effect of BMI on preoperative Spo2 values <96% mediated through atelectasis was 81.5% (95% CI, 56.0-100).

CONCLUSIONS

The prevalence and extension of atelectasis increased with higher BMI, being significantly higher at BMI ≥45 kg/m2. Preoperative atelectasis mediated the effect of BMI on Spo2 at room air in the seated position.

Perioperative Pulmonary Atelectasis: Part II. Clinical Implications

The development of pulmonary atelectasis is common in the surgical patient. Pulmonary atelectasis can cause various degrees of gas exchange and respiratory mechanics impairment during and after surgery. In its most serious presentations, lung collapse could contribute to postoperative respiratory insufficiency, pneumonia, and worse overall clinical outcomes. A specific risk assessment is critical to allow clinicians to optimally choose the anesthetic technique, prepare appropriate monitoring, adapt the perioperative plan, and ensure the patient's safety. Bedside diagnosis and management have benefited from recent imaging advancements such as lung ultrasound and electrical impedance tomography, and monitoring such as esophageal manometry. Therapeutic management includes a broad range of interventions aimed at promoting lung recruitment. During general anesthesia, these strategies have consistently demonstrated their effectiveness in improving intraoperative oxygenation and respiratory compliance. Yet these same intraoperative strategies may fail to affect additional postoperative pulmonary outcomes. Specific attention to the postoperative period may be key for such outcome impact of lung expansion. Interventions such as noninvasive positive pressure ventilatory support may be beneficial in specific patients at high risk for pulmonary atelectasis (e.g., obese) or those with clinical presentations consistent with lung collapse (e.g., postoperative hypoxemia after abdominal and cardiothoracic surgeries). Preoperative interventions may open new opportunities to minimize perioperative lung collapse and prevent pulmonary complications. Knowledge of pathophysiologic mechanisms of atelectasis and their consequences in the healthy and diseased lung should provide the basis for current practice and help to stratify and match the intensity of selected interventions to clinical conditions.

Anesthetic management of patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is the third most common cause of death worldwide. It has a prevalence of 14% among Koreans aged above 40 years and a prevalence of 31% among those aged above 65 years. However, only 6% of the COPD patients receive treatment. Most of the patients do not seek medical attention, as they think that dyspnea, cough, and productive sputum, which are the common symptoms of COPD, are normal aging phenomena. Smoking is a major risk factor for COPD, but environmental hazards and genetic susceptibility are also involved. With aging, lung injuries due to these risk factors accumulate, leading to increased prevalence of COPD. The major concerns regarding perioperative management of COPD patients include preoperative evaluation of cardiopulmonary risks, optimization of lung function, and evaluation of COPD-related physiological functions that are easily aggravated during anesthesia. These include respiratory muscle dysfunction, dynamic hyperinflation and auto-positive end-expiratory pressure, hypoxia-hypercarbia, and pulmonary hypertension-associated heart failure. Therefore, anesthesia for COPD patients should focus on preoperative evaluation, risk reduction measures, and prevention of postoperative pulmonary complications.

Anesthetic considerations in the patients of chronic obstructive pulmonary disease undergoing laparoscopic surgeries

The aim of this study was to review the various anesthetic options which can be considered for laparoscopic surgeries in the patients with the chronic obstructive pulmonary disease. The literature search was performed in the Google, PubMed, and Medscape using key words "analgesia, anesthesia, general, laparoscopy, lung diseases, obstructive." More than thirty-five free full articles and books published from the year 1994 to 2014 were retrieved and studied. Retrospective data observed from various studies and case reports showed regional anesthesia (RA) to be valid and safer option in the patients who are not good candidates of general anesthesia like patients having obstructive pulmonary diseases. It showed better postoperative patient outcome with respect to safety, efficacy, postoperative pulmonary complications, and analgesia. So depending upon disease severity RA in various forms such as spinal anesthesia, paravertebral block, continuous epidural anesthesia, combined spinal epidural anesthesia (CSEA), and CSEA with bi-level positive airway pressure should be considered.

Preoperative evaluation of the patient with pulmonary disease

BACKGROUND AND OBJECTIVES

In daily clinical practice, pulmonary complications related to surgical procedure are common, increasing the morbidity and mortality of patients. Assessment of the risk of pulmonary complications is an important step in the preoperative evaluation. Thus, we review the most relevant aspects of preoperative assessment of the patient with lung disease.

CONTENT

Pulmonary risk stratification depends on clinical symptoms and patient's physical status. Age, preexisting respiratory diseases, nutritional status, and continued medical treatment are usually more important than additional tests. Pulmonary function tests are of great relevance when high abdominal or thoracic procedures are scheduled, particularly when lung resection are considered.

CONCLUSION

Understanding the perioperative evaluation of the potential risk for developing pulmonary complication allows the medical team to choose the adequate anesthetic technique and surgical and clinical care required by each patient, thereby reducing adverse respiratory outcomes.

Complicações respiratórias pós-operatórias em cirurgia bariátrica: revisão da literatura

Obesidade é um problema de saúde pública mundial com altos índices de morbi-mortalidade. A cirurgia bariátrica tem sido o tratamento mais usado e desperta atenção para seu desenvolvimento e resultados. Porém, até o momento, não há revisão sobre a incidência de complicações respiratórias nesta população. O objetivo deste estudo foi revisar a literatura sobre as complicações respiratórias após cirurgias bariátricas convencionais com a utilização das bases de dados PubMed, Cochrane e Scielo buscando os termos: complicações, pulmonar, pós-operatório e cirurgia bariátrica. Os limites foram os últimos dez anos, adultos, inglês e espanhol. Encontramos 69 artigos e utilizamos 21. As complicações respiratórias mais observadas em cirurgia bariátrica são: embolia pulmonar, atelectasias e pneumonia, estando relacionadas à idade e à hipoventilação. A obesidade mórbida está associada a disfunções respiratórias, incluindo diminuição da resistência cardiorrespiratória e dispneia, sendo as alterações mais comuns: diminuição da ventilação e da complacência torácica, taquipneia e aumento do trabalho muscular respiratório, com altos índices de hipoxemia e fadiga respiratória. Nossos resultados mostram que embolia pulmonar, atelectasias e pneumonias são as complicações respiratórias mais incidentes em cirurgias bariátricas convencionais, sendo os idosos ou portadores de síndrome da hipoventilação e apneia obstrutiva do sono os que apresentam maior risco de desenvolvê-las.

Regional anaesthesia in the obese patient: lost landmarks and evolving ultrasound guidance

Obesity is associated with a number of anaesthetic-related risks. Regional anaesthesia offers many potential advantages for the obese surgical patient. Advantages include a reduction in systemic opioid requirements and their associated side effects, and possible avoidance of general anaesthesia in select circumstances, with a lower rate of complications. Historically, performing regional anaesthesia procedures in the obese has presented challenges due to difficulty in identifying surface landmarks and availability of appropriate equipment. Ultrasound guidance may aid the regional anaesthesia practitioner with direct visualisation of underlying anatomic structures and real-time needle direction. Further research is needed to determine optimal regional anaesthesia techniques, local anaesthetic dosage and perioperative outcomes in obese patients.

Pulmonary effects of bupivacaine, ropivacaine, and levobupivacaine in parturients undergoing spinal anaesthesia for elective caesarean delivery: a randomised controlled study

BACKGROUND

Spinal anaesthesia is the method of choice for elective caesarean delivery, but has been reported to worsen dynamic pulmonary function when using bupivacaine. Similar investigations are lacking for ropivacaine and levobupivacaine. We have therefore compared the pulmonary effects of intrathecal bupivacaine, ropivacaine and levobupivacaine used for caesarean delivery.

METHODS

Forced vital capacity, forced expiratory volume in the first second, and peak expiratory flow rate were measured in 48 parturients before and after onset of spinal anaesthesia using either 0.5% bupivacaine 10 mg, 1% ropivacaine 20 mg, or 0.5% levobupivacaine 10 mg. Apgar scores and umbilical arterial pH were recorded.

RESULTS

The final level of sensory blockade was not different between groups. Forced vital capacity was significantly decreased with bupivacaine (3.6+/-0.5 L to 3.5+/-0.4 L, P<0.05) and ropivacaine (3.2+/-0.4 L to 3.1+/-0.5 L, P<0.05), but not with levobupivacaine (3.6+/-0.5 L to 3.4+/-0.6 L). Forced expiratory volume during the first second was not decreased in any group. Peak expiratory flow rate was significantly decreased with ropivacaine (5.5+/-1.5 L/s to 5.0+/-1.1 L/s, P<0.05) and levobupivacaine (from 6.0+/-1.1 L/s to 5.2+/-0.9 L/s, P<0.01). Neonatal vital parameters did not differ between the three groups.

CONCLUSIONS

Decreases in maternal pulmonary function tests were similar following spinal anaesthesia with bupivacaine, ropivacaine, or levobupivacaine for caesarean delivery. The clinical maternal and neonatal effects of these alterations appeared negligible.

Spinal anaesthesia and non-invasive positive pressure ventilation for hip surgery in an obese patient with advanced chronic obstructive pulmonary disease

We describe the use of non-invasive positive pressure ventilation combined with spinal anaesthesia to allow the insertion of a dynamic hip screw in an obese patient with advanced chronic obstructive pulmonary disease. The technique avoided the hazards of intubation and general anaesthesia in this high-risk patient.

The challenges of obesity and obstetric anaesthesia

PURPOSE OF REVIEW

The aim of this article is to review the clinical challenges of obesity in obstetrics from the anaesthetist's viewpoint.

RECENT FINDINGS

The prevalence of obesity continues to increase both in the community and on the labour ward. Women who have undergone bariatric surgery are also on rise. During pregnancy, obesity is associated with hypertensive disease (chronic hypertension and preeclampsia), diabetes mellitus (pregestational and gestational), respiratory disorders (asthma and sleep apnoea), thromboembolic disease, caesarean section and infections (primarily urinary tract infections, wound infections and endometritis). Obesity is a risk factor for anaesthesia-related maternal mortality. Obese women are not only at high-risk of airway complications, cardiopulmonary dysfunction, perioperative morbidity and mortality but also pose technical challenges. Obesity also influences the fetal outcomes. Increasing use of regional techniques contributes to the reduced anaesthesia-related maternal mortality. Preconception counselling, antenatal screening and anaesthetic assessment are strongly encouraged.

SUMMARY

Effective communication and good teamwork between an anaesthetist and an obstetrician are essential for the care of obese parturients. A more liberalized use of regional techniques may be a means of further reducing the anaesthesia-related maternal mortality.