The upper airway during anaesthesia

Multidisciplinary management of Hunter syndrome

Hunter syndrome is a rare, X-linked disorder caused by a deficiency of the lysosomal enzyme iduronate-2-sulfatase. In the absence of sufficient enzyme activity, glycosaminoglycans accumulate in the lysosomes of many tissues and organs and contribute to the multisystem, progressive pathologies seen in Hunter syndrome. The nervous, cardiovascular, respiratory, and musculoskeletal systems can be involved in individuals with Hunter syndrome. Although the management of some clinical problems associated with the disease may seem routine, the management is typically complex and requires the physician to be aware of the special issues surrounding the patient with Hunter syndrome, and a multidisciplinary approach should be taken. Subspecialties such as otorhinolaryngology, neurosurgery, orthopedics, cardiology, anesthesiology, pulmonology, and neurodevelopment will all have a role in management, as will specialty areas such as physiotherapy, audiology, and others. The important management topics are discussed in this review, and the use of enzyme-replacement therapy with recombinant human iduronate-2-sulfatase as a specific treatment for Hunter syndrome is presented.

[Residual curarization and pharyngeal muscles: remain vigilant!]

The different concepts treating of "residual curarization" were presented according to two directions: the analysis of their contents--epidemiologic, clinical, instrumental--and the description of the pharyngeal striated muscles functions in these contexts. It appears that certain, too marked, "residual curarization" levels remain a well-evidenced factor increasing some morbidities in numerous clinical situations. All the methods of instrumental monitoring of the level of curarization--mecanography, electromyography, accelerometry--appeared useful to document the levels of "residual curarization" before patient's extubation or awakening. Today, for our speciality, it became particularly clear that: neither the selected muscle-- adductor pollicis--, neither the test currently privileged--train-of-four 2Hz--, nor the thresholds currently selected--0.90 or 1.00--did not constitute the unavoidable proof of a "residual curarization" complete absence. For the healthy volunteer receiving a curare, a train of four of the adductor pollicis greater than 0.90 can exist in presence of spirometric alterations evidencing the lack of adequate pharyngeal dilatation. In daily routine, the pharyngeal control is already disturbed by numerous molecules including: benzodiazepines, halogenated vapours, propofol, i.e. even under non-hypnotic concentrations. Faced to such evidences, our medical speciality will, undoubtedly, have to acquire new knowledge to develop muscle relaxant management control processes eliminating the surmorbidities related to "residual curarization". These tests must be validated also to exclude morbidity-prone dysfunctions of the pharyngeal striated muscles. Considering this new paradigm would be a major safety evolution for our speciality.

Contribution of male sex, age, and obesity to mechanical instability of the upper airway during sleep

Male sex, obesity, and age are risk factors for obstructive sleep apnea, although the mechanisms by which these factors increase sleep apnea susceptibility are not entirely understood. This study examined the interrelationships between sleep apnea risk factors, upper airway mechanics, and sleep apnea susceptibility. In 164 (86 men, 78 women) participants with and without sleep apnea, upper airway pressure-flow relationships were characterized to determine their mechanical properties [pharyngeal critical pressure under hypotonic conditions (passive Pcrit)] during non-rapid eye movement sleep. In multiple linear regression analyses, the effects of body mass index and age on passive Pcrit were determined in each sex. A subset of men and women matched by body mass index, age, and disease severity was used to determine the sex effect on passive Pcrit. The passive Pcrit was 1.9 cmH(2)O [95% confidence interval (CI): 0.1-3.6 cmH(2)O] lower in women than men after matching for body mass index, age, and disease severity. The relationship between passive Pcrit and sleep apnea status and severity was examined. Sleep apnea was largely absent in those individuals with a passive Pcrit less than -5 cmH(2)O and increased markedly in severity when passive Pcrit rose above -5 cmH(2)O. Passive Pcrit had a predictive power of 0.73 (95% CI: 0.65-0.82) in predicting sleep apnea status. Upper airway mechanics are differentially controlled by sex, obesity, and age, and partly mediate the relationship between these sleep apnea risk factors and obstructive sleep apnea.

Recovery profile of patients undergoing nasal surgical procedures: a comparison between sevoflurane and propofol

OBJECTIVES

To compare the recovery profile of sevoflurane and propofol in nasal surgical procedures.

DESIGN

A prospective, double blind, randomized study

SETTING

King Abdul Aziz University Hospital, Riyadh, Saudi Arabia, a tertiary care teaching hospital, attached with King Saud University, Riyadh Saudi Arabia.

PATIENTS

60 ASA I-II patients age between 18-35 years, and weighing 50-80 kg, scheduled for nasal surgical procedures.

METHODS

Patients were assigned randomly to one of the two groups, the Sevoflurane Group-S (n = 30) & the Propofol Group-P (n = 30). Anesthetic induction was carried out using propofol 2.0mg/kg.in both the groups. Cis-atracurium 0.15mg/kg was given for intubation. Airway was protected with a throat pack around the endo-tracheal tube. Fentanyl 1microgram/kg was given as bolus followed by infusion at a rate of 1 microgram/kg/ hour. Anesthesia was maintained with sevoflurane 2% in Group-S, and propofol infusion at a rate of 200 microgram/kg/min. in Group-P. 50% oxygen in nitrous oxide was given in both the groups. At the end of surgery, patients were extubated after reversal of the neuromuscular block. Immediate recovery was assessed by recording the time to breathe spontaneously, time to extubation, and time of spontaneous eyes movements from the time of giving reversal. Ketoprofen 1.5mg/kg intramuscularly was given to all patients before transfer to (PACU). In PACU, sedation score was assessed for 45 min. Intermediate recovery was assessed by TDT and DSST at 15, 30 and 45 min. Time taken to state name and father's name was recorded.

RESULTS

Patients in Group-S breathed significantly earlier than those in Group-P. Group-P showed significantly better performance with TDT at 45 min and with DSST at 30 and 45 min.

CONCLUSIONS

We conclude that both sevoflurane and propofol provide early and comparable post anesthesia recovery for patients undergoing nasal surgical procedures.

The impact of perioperative dexmedetomidine infusion on postoperative narcotic use and duration of stay after laparoscopic bariatric surgery

Dexmedetomidine (Precedex, Hospira, Lake Forest, IL) is an alpha-2 receptor agonist with sedative and analgesic sparing properties. This medication has not been associated with respiratory suppression, despite occasionally high levels of sedation. For 10 months, all patients undergoing a laparoscopic bariatric procedure received a dexmedetomidine infusion 30 min before the anticipated completion of the procedure (n = 34). A control group was comprised of a similar number of patients to have had laparoscopic bariatric surgery in the time period immediately before these 10 months (n = 37). All pathways and discharge criteria were identical for patients in each group. A total of 73 patients were included in this retrospective chart review. Two gastric bypass patients were excluded for complications requiring additional surgery (one bleed and one leak). Gastric bypass patients who received a dexmedetomidine infusion required fewer narcotics (66 vs 130 mg of morphine equivalents) than control patients and met discharge criteria on post-op day (POD) 1 more often (61% discharged POD 1 vs 26% discharged POD 1, p = 0.02). Vital signs and pain scores were similar in all groups. Dexmedetomidine infusion perioperatively is safe and may help to minimize narcotic requirements and decrease duration of stay after laparoscopic bariatric procedures. This may have important patient safety ramifications in a patient population with a high prevalence of obstructive sleep apnea. A well-organized prospective, randomized, double-blinded trial is necessary to confirm the benefits of dexmedetomidine suggested by this study.

Anesthetic complications of gross obesity

PURPOSE OF REVIEW

The number of obese patients undergoing anesthesia and surgery is increasing. This article aims to present recent achievements in the management of gross and morbidly obese patients in order to improve safety.

RECENT FINDINGS

Current investigations have demonstrated that the type of anesthesia (total intravenous anesthesia or volatile) and the anesthetics used have an important influence on the perioperative period, especially on postanesthesia recovery and respiratory failure during the postoperative period. These findings were compared with previous publications. Practical advice is also presented for performing successful intubation and mechanical ventilation in the morbidly obese patient, as well as describing drug dosage and administration.

SUMMARY

The progress in anesthesia techniques and modern drugs allows for safe management of obese patients, with mortality decreasing in this group of patients.

Crisis management during anaesthesia: obstruction of the natural airway

BACKGROUND

Obstruction of the natural airway, while usually easily recognised and managed, may present simply as desaturation, have an unexpected cause, be very difficult to manage, and have serious consequences for the patient.

OBJECTIVES

To examine the role of a previously described core algorithm "COVER ABCD-A SWIFT CHECK", supplemented by a specific sub-algorithm for obstruction of the natural airway, in the management of acute airway obstruction occurring in association with anaesthesia.

METHODS

The potential performance for this structured approach for each of the relevant incidents among the first 4000 reported to the Australian Incident Monitoring Study (AIMS) was compared with the actual management as reported by the anaesthetists involved.

RESULTS

There were 62 relevant incidents among the first 4000 reports to the AIMS. It was considered that the correct use of the structured approach would have led to earlier recognition of the problem and/or better management in 11% of cases.

CONCLUSION

Airway management is a fundamental anaesthetic responsibility and skill. Airway obstruction demands a rapid and organised approach to its diagnosis and management and undue delay usually results in desaturation and a potential threat to life. An uncomplicated pre-learned sequence of airway rescue instructions is an essential part of every anaesthetist's clinical practice requirements.

Perianesthesia respiratory care of the bariatric patient

Our nation's obesity problem has reached epidemic proportions and is only projected to worsen. The morbidly obese patient is at risk for experiencing a multitude of health-related conditions. Morbidly obese patients are presenting for surgery at an increasing rate, especially with the growing popularity of weight-loss surgery. Therefore the perianesthesia nurse has to remain informed of optimal care strategies for this sometimes challenging population. The obese patient presents with distinct respiratory care considerations of which the perianesthesia nurse must be knowledgeable. This review article will specifically focus on the respiratory care of the bariatric patient presenting for surgery.

Desflurane vs. sevoflurane as the main inhaled anaesthetic for spontaneous breathing via a laryngeal mask for varicose vein day surgery: a prospective randomized study

BACKGROUND

Sevoflurane has become widely used in day surgery; however, desflurane may be a valuable alternative even in this setting. This study compares emergence from anaesthesia for day surgery with spontaneous breathing using either desflurane or sevoflurane.

METHODS

This prospective, randomized, single-blinded study examined 70 ASA III patients undergoing elective ambulatory varicose vein surgery. Primary endpoint was emergence time (cessation of anaesthetic gas to communicating). Secondary endpoints included post-operative pain, nausea, time to discharge, and patient satisfaction. Patients were anaesthetized according to a standardized protocol including multimodal analgesia and antiemetic therapy and were randomized to receive sevoflurane or desflurane as the main anaesthetic while breathing spontaneously through a laryngeal mask airway. Fresh gas flow was oxygen in air 1 : 2 l/min.

RESULTS

Intra-operative anaesthesia was uneventful apart from airway irritation observed in 5/35 desflurane and 1/35 sevoflurane patients. Emergence was 25-40% faster in patients anaesthetized with desflurane. Pain and post-operative nausea and vomiting (PONV) were equally infrequent in both groups. Overall, patient satisfaction was high with no difference between the groups.

CONCLUSION

Desflurane is associated with a faster emergence with no differences during the post-operative course except a somewhat higher incidence of airway irritation.

Safety culture and crisis resource management in airway management: general principles to enhance patient safety in critical airway situations

Airway management is a cornerstone of patient safety in anaesthesiology and in emergency and critical care medicine. Deficiencies in airway management could have catastrophic results for the patient. In anaesthesia patients, in particular, a high level of safety should be expected. It has been proven in other high-risk and complex industrial fields that obtaining very high levels of safety requires special strategies and safety philosophies in order to guarantee long-term low-risk production. The concept of safety culture has invaded many industries, more recently including medicine. Concepts of the high reliability organizations (HROs) are now ready to be adapted to medicine and offer promising improvements in health care. This paper applies some of the HRO principles to airway management and illustrates how to transform more general strategies to practical application in the clinical world. This includes the use of key elements of crisis resource management (CRM) and the development of a checklist for safety in airway management.

The Rapid Sequence Induction Revisited: Obesity and Sleep Apnea Syndrome

Pulmonary aspiration is a cause of anesthesia-related morbidity and mortality, with little change in incidence over the past 20 years. Rapid sequence induction is a common procedure in obese patients, who appear to be more at risk for both pulmonary gastric aspiration and difficult airways, and is required in obese and sleep apnea syndrome patients with symptomatic gastroesophageal reflux or other predisposing conditions. In the elective obese or sleep apnea patient with no other risk factors for pulmonary aspiration, the risks and benefits of rapid sequence induction and cricoid pressure should be weighed. If rapid sequence induction is required, succinylcholine remains the neuromuscular blocking agent of choice, if there are no contraindications.

Obstructive sleep apnoea and anaesthesia

Upper airway obstruction is common during both anaesthesia and sleep, as a result of loss of muscle tone present during wakefulness. Patients with obstructive sleep apnoea (OSA) are vulnerable during anaesthesia and sedation as the effects of loss of wakefulness are compounded by drug-induced depression of muscle activity and of arousal responses, so that they cannot respond to asphyxia. Conversely, those with 'difficult' airways during anaesthesia, either because of problems with maintenance of airway patency without tracheal intubation or because intubation itself is problematic, are at increased risk of OSA. These relationships have clinical importance. On the one hand identification of patients with OSA forewarns the anaesthetist of potential difficulty with airway maintenance intra- and postoperatively, influencing choice of anaesthetic technique and postoperative nursing environment. On the other hand difficulty with airway maintenance during anaesthesia should prompt further investigation for the possibility of OSA.

Morbidity and mortality related to anaesthesia outside the operating room

PURPOSE OF REVIEW

The purpose of this review is to provide information related to morbidity and mortality associated with anaesthesia outside the operating room.

RECENT FINDINGS

There is an increasing demand for anaesthesia at remote locations. Because of its specific characteristics, resulting from the location and the patient, morbidity and mortality rates of remote location anaesthesia could differ from conventional operating room anaesthesia. However, no studies are currently available. On the basis of morbidity and mortality data from conventional operating room anaesthesia, we reached some important conclusions with regard to the safety of anaesthesia outside the operating room. A well-equipped anaesthesia machine, standard monitoring (electrocardiogram, oxygen saturation and non-invasive blood pressure), trained personnel and adequate planning should be standard for all out of the operating room procedures. When all these are in place, the incidence of morbidity or mortality should be comparable to that of anaesthesia provided in the operating room.

SUMMARY

There is certainly a need for studies concerning morbidity and mortality at remote location anaesthesia. Special care for the prevention of hypothermia should be given to those patients undergoing long-lasting diagnostic procedures, e.g. magnetic resonance imaging scans or cardiological investigations.

The pediatric airway

Good airway management technique is an essential skill for physicians in most specialties. This article begins with a review of basic airway anatomy and the physiology of the uninstrumented airway. This subject is of particular importance given the increasing use of procedural sedation and the increased recognition of sleep-disordered breathing in infants and children. A discussion of the various artificial airways and their advantages and disadvantages follows. The difficult airway is an important contributor to both patient morbidity and mortality. It is important to have a planned management approach available for the anticipated and, more importantly, the unanticipated difficult airway. The recommendations of the American Society of Anesthesiologists Taskforce on the Management of the Difficult Airway have good application for this important problem. The fetus with the prenatal diagnosis of a lesion that predicts a difficult airway presents a particular challenge. The utilization of an ex-utero intrapartum treatment method is presented as an important approach for the delivery and airway management of these infants. This section closes with a discussion of the prehospital airway management of the pediatric patient.

Update and review of moderate and deep sedation

The administration of sedation/analgesia to allow patients to tolerate diagnostic or therapeutic procedures and tests is a fact of life. Approximately 200,000,000 such sedations are administered every year in the United States. Any morbidity or mortality associated with sedation is likely to be deemed avoidable. There will never be adequate resources or personnel so that trained anesthesia providers administer all sedations, and there probably is no need for such an approach. Clinicians from many specialties now safely and effectively administer sedation. With attention to updated guidelines and concepts, as outlined in this article, the safety and efficacy of sedation/analgesia can and should be excellent.