Preet Mohinder Singh

Postoperative analgesia in morbid obesity.

Morbidly obese patients due to high incidence of obstructive sleep apnea (OSA) are predisposed to opioid induced airway obstruction and thus frontline high ceiling analgesics (opioids) have concerns based on safety in their liberal use. Although surgical techniques over the last two decades have seen a paradigm shift from open to laparoscopic procedures for morbidly obese patients; optimally titrated yet safe analgesic management still remains a challenge. The present review sums up the analgesic options available for management of morbidly obese patients undergoing surgery. We highlight the utility of multimodal approach for analgesia with combinations of agents to decrease opioids requirements. Pre-emptive analgesia may be additionally used to improve the efficacy of postoperative pain relief while allowing further reductions in opioid requirements.

Significantly reduced hypoxemic events in morbidly obese patients undergoing gastrointestinal endoscopy: Predictors and practice effect

Background: Providing anesthesia for gastrointestinal (GI) endoscopy procedures in morbidly obese patients is a challenge for a variety of reasons. The negative impact of obesity on the respiratory system combined with a need to share the upper airway and necessity to preserve the spontaneous ventilation, together add to difficulties. Materials and Methods: This retrospective cohort study included patients with a body mass index (BMI) >40 kg/m2 that underwent out-patient GI endoscopy between September 2010 and February 2011. Patient data was analyzed for procedure, airway management technique as well as hypoxemic and cardiovascular events. Results: A total of 119 patients met the inclusion criteria. Our innovative airway management technique resulted in a lower rate of intraoperative hypoxemic events compared with any published data available. Frequency of desaturation episodes showed statistically significant relation to previous history of obstructive sleep apnea (OSA). These desaturation episodes were found to be statistically independent of increasing BMI of patients. Conclusion: Pre-operative history of OSA irrespective of associated BMI values can be potentially used as a predictor of intra-procedural desaturation. With suitable modification of anesthesia technique, it is possible to reduce the incidence of adverse respiratory events in morbidly obese patients undergoing GI endoscopy procedures, thereby avoiding the need for endotracheal intubation.

Anesthesia for gastrointestinal endoscopy in patients with left ventricular assist devices: Initial experience with 68 procedures

AIMS AND OBJECTIVES Continuous flow left ventricular assist devices (LVAD) have emerged as a reliable treatment option for heart failure. Because of bleeding secondary to anticoagulation, these patients present frequently for gastrointestinal (GI) endoscopy. The presently available literature on perioperative management of these patients is extremely limited and is primarily based upon theoretical principles. MATERIALS AND METHODS Perioperative records of patients with LVAD undergoing (GI) endoscopy between 2008 and 2012 were reviewed. Patient, device and procedure specific information was analyzed. RESULTS A total of 105 LVADs were implanted, and 68 procedures were performed in 39 patients. The most common indication was GI bleed (48/68), with yearly risk of 8.57% per patient. A total of 63 procedures were performed under deep sedation, with five procedures requiring general anesthesia. Intra-procedure hypotension was managed by fluids and (or) vasopressors/inotropes (phenylephrine, ephedrine or milrinone) guided by plethysmographic waveform, non-invasive blood pressure (NIBP) and LVADs pulsatility index (for HeartMate II)/flow pulsatility (for HeartWare). No patient required invasive monitoring and both NIBP and pulse oximeter could be reliably used for monitoring (and guided management) in all patients due to the presence of native hearts pulsatile output. CONCLUSION In the presence of residual heart function, with optimal device settings, non-invasive hemodynamic monitoring can be reliably used in these patients while undergoing GI endoscopy under general anesthesia or monitored anesthesia care. Transient hypotensive episodes respond well to fluids/vasopressors without the need of increasing device speed that can be detrimental.

SEDASYS®, Airway, Oxygenation, and Ventilation: Anticipating and Managing the Challenges

In May 2013, the FDA (Federal Drug Administration) approved SEDASYS®, a device that enables non-anesthesia physicians to provide mild-to-moderate sedation to patients undergoing colonoscopy and esophagogastroduodenoscopy. SEDASYS® is the first among the devices being built to provide computer-assisted personalized sedation. Although the intention of this approval is to cut the anesthesia related expenses, it is likely to create new challenges to the users—both clinical and administrative—that might even increase the cost. Deep sedation is required frequently for a successful completion of the procedure, which poses unforeseen challenges. The present review aims to provide clear information to the users regarding pre-procedure assessment, possible sedation related complications and management options.

ERCP: The Unresolved Question of Endotracheal Intubation

The anesthesia community is still divided as to the appropriate airway management in patients undergoing endoscopic retrograde cholangiopancreatography. Increasingly, gastroenterologists are comfortable with deep sedation (normally propofol) without endotracheal intubation. There are no comprehensive reviews addressing the various pros and cons of an un-intubated airway management. It is hoped that the present review will benefit both anesthesia providers and gastroenterologists. The reasons to avoid routine endotracheal intubation and the approaches for an un-intubated anesthetic management are discussed. The special situations where endotracheal intubation is the preferred approach are mentioned. Many special techniques to manage airway are illustrated.

Remimazolam: The future of its sedative potential

Remimazolam (CNS 7056) is a new drug innovation in anesthesia. It combines the properties of two unique drugs already established in anesthesia – Midazolam and remifentanil. It acts on GABA receptors like midazolam and has organ-independent metabolism like remifentanil. It is likely to be the sedative of the future, as preliminary phase II trials have shown minimal residual effects on prolonged infusions. It has potential to be used as a sedative in ICU and as a novel agent for procedural sedation. Unlike most rapidly acting intravenous sedatives available presently, the propensity to cause apnea is very low. Availability of a specific antagonist (flumazenil) adds to its safety even in cases of overdose. The present review discusses remimazolams potential as a new drug in anesthesia along with the presently available literary evidence.

Effectiveness of high dose remifentanil in preventing coughing and laryngospasm in non-paralyzed patients for advanced bronchoscopic procedures

BACKGROUND: Anesthesia for bronchoscopy presents unique challenges, as constant stimulus due to bronchoscope needs to be obtunded using drugs with a minimal post-procedure residual effect. Remifentanil for maintenance is an ideal choice, but optimal doses are yet to be determined. MATERIALS AND METHODS: Bronchoscopic procedures were prospectively evaluated for 4 months studying the frequency of complications and anesthesia techniques. Anesthesia was maintained on remifentanil/propofol infusion avoiding neuromuscular blockers. Laryngeal mask airway was used for the controlled ventilation (with high oxygen concentration) that also served as a conduit for bronchoscope insertions. Anesthesiologists were blinded to the study (avoiding performance bias) and the Pulmonologist was blinded to the anesthesia technique (to document unbiased procedural satisfaction scores). Procedures were divided into 2 groups based on the dose of remifentanil used for maintenance: Group-H (high dose −0.26 to 0.5 μg/kg/min and Group-NH (non-high dose ≤0.25 μg/kg/min). RESULTS: Observed 75 procedures were divided into Group-H (42) and Group-NH (33). Number of statistical difference was found in demography, procedural profile, hemodynamic parameters and total phenylephrine used. Chi-square test showed Group-NH had significantly higher frequency of laryngospasm (P = 0.047) and coughing (P = 0.002). The likelihood ratio of patient coughing and developing laryngospasm in Group-NH was found to be 4.56 and 10.97 times respectively. Minimum pulse-oximeter saturation was statistically higher in Group-H (98.80% vs. 96.50% P = 0.009). Pulmonologist satisfaction scores were significantly better in Group-H. CONCLUSIONS: High dose of remifentanil infusion is associated with a lower incidence of coughing and laryngospasms during bronchoscopy. Simultaneously, it improves Pulmonologists satisfaction and procedural conditions.

Changing trends of hemodynamic monitoring in ICU - from invasive to non-invasive methods: Are we there yet?

Hemodynamic monitoring in the form of invasive arterial, central venous pressure and pulmonary capillary wedge pressure monitoring may be required in seriously ill Intensive care unit patients, in patients undergoing surgeries involving gross hemodynamic changes and in patients undergoing cardiac surgeries. These techniques are considered the gold standards of hemodynamic monitoring but are associated with their inherent risks. A number of non-invasive techniques based on various physical principles are under investigation at present. The goal is to not only avoid the risk of invasive intervention, but also to match the gold standard set by them as far as possible. Techniques based on photoplethysmography, arterial tonometry and pulse transit time analysis have come up for continuous arterial pressure monitoring. Of these the first has been studied most extensively and validated, however it has been shown to be substandard in patients with gross hemodynamic instability. The other two still need further evaluation. While the non-invasive methods for arterial blood pressure monitoring are based on diverse technologies, those for measurement of central venous and pulmonary pressures are mostly based on imaging techniques such as echocardiography, Doppler ultrasound, computed tomography scan and chest X ray. Most of these techniques are based on measurement of the dimensions of the great veins. This makes them operator and observer dependent. However, studies done till now have revealed adequate inter-observer agreement. These techniques are still in their incipience and although initial studies are encouraging, further research is needed on this front.

Effect of peribulbar block on emergence agitation in children undergoing strabismus surgery under desflurane anaesthesia

Background: Strabismus surgery in children may be associated with a high incidence of emergence agitation that may be related to pain and visual disturbances. The objective was to evaluate the effect of peribulbar block on the incidence of emergence agitation in children undergoing strabismus surgery under desflurane anaesthesia. Methods: Fifty-six healthy children aged 2–10 years, undergoing strabismus surgery under general anaesthesia, were recruited. Children were randomly allocated to receive fentanyl 2 µg/kg (Group F) or peribulbar block (Group PB) with 0.3 ml/kg of 0.25% bupivacaine + 2% lignocaine. The primary outcome of the study was incidence of emergence agitation; secondary outcome measures were time to first rescue analgesia, the incidence of oculocardiac reflex and vomiting. Results: Of 52 children, 14/25 (56%) children in Group F developed emergence agitation compared with 3/27 (11.11%) in group PB (p = 0.001). Postoperatively, the paediatric anaesthesia emergence delirium scores showed significantly lower emergence agitation in the PB group with a median (IQR) of 0.00 (0.00–2.00) compared with group F (5.5 (0.75–8.75) at all time intervals (p = 0.003 Mann–Whitney test). Pain scores were comparable between groups (group F 48% vs. group PB 25.9%). The time to first rescue analgesia was increased in group PB (126.875 ± 38.22 min vs. 88.08 ± 28.48 min in group F). The oculocardiac reflex occurred in 7/25 in Group F compared with 1/27 in Group PB (p = 0.015). There was no difference in the incidence of postoperative vomiting (24% in Group F vs. 22% in Group PB). Conclusion: Use of peribulbar block in children undergoing strabismus surgery under desflurane anaesthesia was associated with reduced incidence of emergence agitation and oculocardiac reflex but did not significantly increase the time to first analgesic or the incidence of pain and vomiting. A sub-tenon block may be safer and provide better operating conditions and equal analgesia.