How can I manage anaesthesia in obese patients?

Extubation-Related Complications

Extubation represents an essential component of airway management. While being a common procedure in anesthesiology and critical care medicine, it is accompanied by a significant risk of morbidity and mortality. Safe extubation requires considerable skills, risk stratification and advanced planning. It is important to emphasize that intentional extubation is always an elective procedure, and as such should only be executed when conditions are optimal. The purpose of this review is to discuss the complications associated with planned extubation in the adult patient, including risk factors and management strategies, mainly focusing on the postoperative setting.

Effects of starting one lung ventilation and applying individualized PEEP right after patients are placed in lateral decubitus position on intraoperative oxygenation for patients undergoing thoracoscopic pulmonary lobectomy: study protocol for a randomized controlled trial

BACKGROUND

For patients receiving one lung ventilation in thoracic surgery, numerous studies have proved the superiority of lung protective ventilation of low tidal volume combined with recruitment maneuvers (RM) and individualized PEEP. However, RM may lead to overinflation which aggravates lung injury and intrapulmonary shunt. According to CT results, atelectasis usually forms in gravity dependent lung regions, regardless of body position. So, during anesthesia induction in supine position, atelectasis usually forms in the dorsal parts of lungs, however, when patients are turned into lateral decubitus position, collapsed lung tissue in the dorsal parts would reexpand, while atelectasis would slowly reappear in the lower flank of the lung. We hypothesize that applying sufficient PEEP without RM before the formation of atelectasis in the lower flank of the lung may beas effective to prevent atelectasis and thus improve oxygenation as applying PEEP with RM.

METHODS

A total of 84 patients scheduled for elective pulmonary lobe resection necessitating one lung ventilation will be recruited and randomized totwo parallel groups. For all patients, one lung ventilation is initiated the right after patients are turned into lateral decubitus position. For patients in the study group, individualized PEEP titration is started the moment one lung ventilation is started, while patients in the control group will receive a recruitment maneuver followed by individualized PEEP titration after initiation of one lung ventilation. The primary endpoint will be oxygenation index measured at T4. Secondary endpoints will include intrapulmonary shunt, respiratory mechanics, PPCs, and hemodynamic indicators.

DISCUSSION

Numerous previous studies compared the effects of individualized PEEP applied alone with that applied in combination with RM on oxygenation index, PPCs, intrapulmonary shunt and respiratory mechanics after atelectasis was formed in patients receiving one lung ventilation during thoracoscopic surgery. In this study, we will apply individualized PEEP before the formation of atelectasis while not performing RM in patients allocated to the study group, and then we're going to observe its effects on the aspects mentioned above. The results of this trial will provide a ventilation strategy that may be conductive to improving intraoperative oxygenation and avoiding the detrimental effects of RM for patients receiving one lung ventilation.

TRIAL REGISTRATION

www.Chictr.org.cn ChiCTR2400080682. Registered on February 5, 2024.

General Anesthetic Care of Obese Patients Undergoing Surgery: A Review of Current Anesthetic Considerations and Recent Advances

Obesity has long been linked to adverse health effects over time. As the prevalence of obesity continues to rise, it is important to anticipate and minimize the complications that obesity brings in the anesthesia setting during surgery. Anesthetic departments must recognize the innumerable risks when managing patients with obesity undergoing surgery, including anatomical and physiological changes as well as comorbidities such as diabetes, cardiovascular diseases, and malignancies. Therefore, the purpose of this review is to analyze the current literature and evaluate the current and recent advances in anesthetic care of obese patients undergoing surgery, to better understand the specific challenges this patient population faces. A greater understanding of the differences between anesthetic care for obese patients can help to improve patient care and the specificity of treatment. The examination of the literature will focus on differing patient outcomes and safety precautions in obese patients as compared to the general population. Specifically highlighting the differences in pre-operative, intra-operative, and post-operative care, with the aim to identify issues and present possible solutions.

Preoxygenation with standard facemask combining apnoeic oxygenation using high flow nasal cannula versuss standard facemask alone in patients with and without obesity: the OPTIMASK international study

BACKGROUND

Combining oxygen facemask with apnoeic oxygenation using high-flow-nasal-oxygen (HFNO) for preoxygenation in the operating room has not been studied against standard oxygen facemask alone. We hypothesized that facemask-alone would be associated with lower levels of lowest end-tidal oxygen (EtO2) within 2 min after intubation in comparison with facemask combined with HFNO.

METHODS

In an international prospective before-after multicentre study, we included adult patients intubated in the operating room from September 2022 to December 2022. In the before period, preoxygenation was performed with facemask-alone, which was removed during laryngoscopy. In the after period, facemask combined with HFNO was used for preoxygenation and HFNO for apnoeic oxygenation during laryngoscopy. HFNO was maintained throughout intubation. The primary outcome was the lowest EtO2 within 2 min after intubation. The secondary outcome was SpO2 ≤ 95% within 2 min after intubation. Subgroup analyses were performed in patients without and with obesity. This study was registered 10 August 2022 with ClinicalTrials.gov, number NCT05495841.

RESULTS

A total of 450 intubations were evaluated, 233 with facemask-alone and 217 with facemask combined with HFNO. In all patients, the lowest EtO2 within 2 min after intubation was significantly lower with facemask-alone than with facemask combined with HFNO, 89 (85-92)% vs 91 (88-93)%, respectively (mean difference - 2.20(- 3.21 to - 1.18), p < 0.001). In patients with obesity, similar results were found [87(82-91)% vs 90(88-92)%, p = 0.004]; as in patients without obesity [90(86-92)% vs 91(89-93)%, p = 0.001)]. SpO2 ≤ 95% was more frequent with facemask-alone (14/232, 6%) than with facemask combined with HFNO (2/215, 1%, p = 0.004). No severe adverse events were recorded.

CONCLUSIONS

Combining facemask with HFNO for preoxygenation and apnoeic oxygenation was associated with increased levels of lowest EtO2 within 2 min after intubation and less desaturation.

Case Report: Downbeat Nystagmus Due to Epidural Puncture during Labor with Undiagnosed Arnold Chiari Malformation

SIGNIFICANCE

Epidural anesthesia is a safe procedure used in pregnant patients during labor. However, caution should be exercised in those patients that have concurrent Arnold Chiari malformation.

PURPOSE

To report a rare and atypical presentation of downbeat nystagmus, in a pregnant patient with Arnold Chiari malformation type 1 (ACM1), secondary to accidental dural puncture.

CASE REPORT

A 31-year-old African American female presented with a chief complaint of decreased vision and oscillopsia that occurred after giving birth, six months earlier. Her medical history prior to presentation was unremarkable. Her delivery was typical; however, the patient did receive epidural anesthesia which resulted in a dural puncture. The patient noted her symptoms a few days after delivery. Upon examination, persistent down beat nystagmus was noted in both eyes. Magnetic resonance imaging revealed a 2.5 cm inferior displacement of the cerebellar tonsils below the foramen magnum consistent with ACM1. The patient was referred to neurosurgery for posterior fossa decompression. However, surgery was deferred until appropriate weight reduction could be achieved. Follow-up examination six months later revealed no change in her clinical findings.

CONCLUSIONS

This case report highlights an atypical presentation of downbeat nystagmus secondary to an accidental dural puncture in a pregnant patient with undiagnosed ACM1. Clinicians should consider the importance of considering ocular complications that can occur in pregnant patients with ACM1. Questioning of women who have recently given birth about epidural anesthesia should be considered with an acute presentation of downbeat-nystagmus.

Opioid-free versus opioid-based anesthesia in pancreatic surgery

BACKGROUND

Opioid-free anesthesia (OFA) is associated with significantly reduced cumulative postoperative morphine consumption in comparison with opioid-based anesthesia (OBA). Whether OFA is feasible and may improve outcomes in pancreatic surgery remains unclear.

METHODS

Perioperative data from 77 consecutive patients who underwent pancreatic resection were included and retrospectively reviewed. Patients received either an OBA with intraoperative remifentanil (n = 42) or an OFA (n = 35). OFA included a combination of continuous infusions of dexmedetomidine, lidocaine, and esketamine. In OBA, patients also received a single bolus of intrathecal morphine. All patients received intraoperative propofol, sevoflurane, dexamethasone, diclofenac, neuromuscular blockade. Postoperative pain management was achieved by continuous wound infiltration and patient-controlled morphine. The primary outcome was postoperative pain (Numerical Rating Scale, NRS). Opioid consumption within 48 h after extubation, length of stay, adverse events within 90 days, and 30-day mortality were included as secondary outcomes. Episodes of bradycardia and hypotension requiring rescue medication were considered as safety outcomes.

RESULTS

Compared to OBA, NRS (3 [2-4] vs 0 [0-2], P < 0.001) and opioid consumption (36 [24-52] vs 10 [2-24], P = 0.005) were both less in the OFA group. Length of stay was shorter by 4 days with OFA (14 [7-46] vs 10 [6-16], P < 0.001). OFA (P = 0.03), with postoperative pancreatic fistula (P = 0.0002) and delayed gastric emptying (P < 0.0001) were identified as only independent factors for length of stay. The comprehensive complication index (CCI) was the lowest with OFA (24.9 ± 25.5 vs 14.1 ± 23.4, P = 0.03). There were no differences in demographics, operative time, blood loss, bradycardia, vasopressors administration or time to extubation among groups.

CONCLUSIONS

In this series, OFA during pancreatic resection is feasible and independently associated with a better outcome, in particular pain outcomes. The lower rate of postoperative complications may justify future randomized trials to test the hypothesis that OFA may improve outcomes and shorten length of stay.

Obesity, metabolic syndrome, and inflammation: an update for anaesthetists caring for patients with obesity

Our understanding of chronic inflammation in obesity is evolving. Suggested mechanisms include hypoxia of adipose tissue and a subsequent increase in circulating cytokines. It is now known that adipose tissue, far from being an inert tissue, produces and secretes multiple peptides that influence inflammation and metabolism, including substrates of the renin-angiotensin-aldosterone system (RAAS). RAAS blocking antihypertensive medication and cholesterol-lowering agents are now being evaluated for their metabolic and inflammation-modulating effects. Surgery also has pro-inflammatory effects, which may be exacerbated in patients with obesity. This narrative review will summarise the recent literature surrounding obesity, metabolic syndrome, inflammation, and interplay with the RAAS, with evidence-based recommendations for the optimisation of patients with obesity, prior to surgery and anaesthesia.

Intraoperative Monitoring of the Obese Patient Undergoing Surgery: A Narrative Review

With the increasing prevalence of obesity in the population, anaesthetists must confidently manage both the pathophysiological and technical challenges presented in bariatric and non-bariatric surgery. The intraoperative period represents an important opportunity to optimise and mitigate risk. However, there is little formal guidance on what intraoperative monitoring techniques should be used in this population. This narrative review collates the existing evidence for intraoperative monitoring devices in the obese patients. Although a number of non-invasive blood pressure monitors have been tested, an invasive arterial line remains the most reliable monitor if accurate, continuous monitoring is required. Goal-directed fluid therapy is recommended by clinical practice guidelines, but the methods tested to assess this had guarded applicability to the obese population. Transcutaneous carbon dioxide (CO₂) monitoring may offer additional benefit to standard capnography in this population. Individually titrated positive end expiratory pressure (PEEP) and recruitment manoeuvres improved intraoperative mechanics but yielded no benefit in the immediate postoperative period. Depth of anaesthesia monitoring appears to be beneficial in the perioperative period regarding recovery times and complications. Objective confirmation of reversal of neuromuscular blockade continues to be a central tenet of anaesthesia practice, particularly relevant to this group who have been characterised as an "at risk" extubation group. Where deep neuromuscular blockade is used, continuous neuromuscular blockade is suggested. Both obesity and the intraoperative context represent somewhat unstable search terms, as the clinical implications of the obesity phenotype are not uniform, and the type and urgency of surgery have significant impact on the intraoperative setting. This renders the generation of summary conclusions around what intraoperative monitoring techniques are suitable in this population highly challenging.

Advanced endoscopic gastrointestinal techniques for the bariatric patient: implications for the anesthesia provider

PURPOSE OF REVIEW

The incidence of obesity and the use of endoscopy have risen concurrently throughout the 21st century. Bariatric patients may present to the endoscopy suite for primary treatments as well as preoperatively and postoperatively from bariatric surgery. However, over the past 10 years, endoscopic bariatric and metabolic therapies (EBMTs) have emerged as viable alternatives to more invasive surgical approaches for weight loss.

RECENT FINDINGS

The United States Food and Drug Administration (FDA) has approved several different gastric EBMTs including aspiration therapy, intragastric balloons, and endoscopic suturing. Other small intestine EBMTs including duodenal mucosal resurfacing, endoluminal magnetic partial jejunal diversion, and Duodenal-Jejunal Bypass Liner are not yet FDA approved, but are actively being investigated.

SUMMARY

Obesity causes anatomic and physiologic changes to every aspect of the human body. All EBMTs have specific nuances with important implications for the anesthesiologist. By considering both patient and procedural factors, the anesthesiologist will be able to perform a safe and effective anesthetic.

Perioperative Noninvasive Ventilation After Adult or Pediatric Surgery: A Comprehensive Review

Postoperative pulmonary complications and acute respiratory failure are among the leading causes of adverse postoperative outcomes. Noninvasive ventilation may safely and effectively prevent acute respiratory failure in high-risk patients after cardiothoracic surgery and after abdominal surgery. Moreover, noninvasive ventilation can be used to treat postoperative hypoxemia, particularly after abdominal surgery. Noninvasive ventilation also can be helpful to prevent or manage intraoperative acute respiratory failure during non-general anesthesia, primarily in patients with poor respiratory function. Finally, noninvasive ventilation is superior to standard preoxygenation in delaying desaturation during intubation in morbidly obese and in critically ill hypoxemic patients. The few available studies in children suggest that noninvasive ventilation could be safe and valuable in treating hypoxemic or hypercapnic acute respiratory failure after cardiac surgery; on the other hand, it could be dangerous after tracheoesophageal correction.

How to ventilate obese patients in the ICU

Obesity is an important risk factor for major complications, morbidity and mortality related to intubation procedures and ventilation in the intensive care unit (ICU). The fall in functional residual capacity promotes airway closure and atelectasis formation. This narrative review presents the impact of obesity on the respiratory system and the key points to optimize airway management, noninvasive and invasive mechanical ventilation in ICU patients with obesity. Non-invasive strategies should first optimize body position with reverse Trendelenburg position or sitting position. Noninvasive ventilation (NIV) is considered as the first-line therapy in patients with obesity having a postoperative acute respiratory failure. Positive pressure pre-oxygenation before the intubation procedure is the method of reference. The use of videolaryngoscopy has to be considered by adequately trained intensivists, especially in patients with several risk factors. Regarding mechanical ventilation in patients with and without acute respiratory distress syndrome (ARDS), low tidal volume (6 ml/kg of predicted body weight) and moderate to high positive end-expiratory pressure (PEEP), with careful recruitment maneuver in selected patients, are advised. Prone positioning is a therapeutic choice in severe ARDS patients with obesity. Prophylactic NIV should be considered after extubation to prevent re-intubation. If obesity increases mortality and risk of ICU admission in the overall population, the impact of obesity on ICU mortality is less clear and several confounding factors have to be taken into account regarding the “obesity ICU paradox”.