Gastric distension and ventilation during laparoscopic cholecystectomy: LMA-Classic vs. tracheal intubation

PURPOSE

The standard laryngeal mask airway LMA-Classic was designed as an alternative to the endotracheal tube (ETT) or the face mask for use with either spontaneous or positive pressure ventilation. Positive pressure ventilation may exploit leaks around the LMA cuff, leading to gastric distension and/or inadequate ventilation. We compared gastric distension and ventilation parameters with LMA vs ETT during laparoscopic cholecystectomy.

METHODS

One hundred and one, ASA I-II adults scheduled for elective laparoscopic cholecystectomy were randomly assigned to LMA-Classic or ETT. Patients with BMI >30 kg x m(-2), hiatus hernia or gastroesophageal reflux were excluded. Following induction of anesthesia, an in-and-out orogastric tube was passed to decompress the stomach before insertion of the LMA (women size #4, men size #5) or ETT (women 7 mm, men 8 mm). Anesthesia was maintained with isoflurane in nitrous oxide and oxygen (FIO2 0.3-0.5), rocuronium and fentanyl. The surgeon, blinded to the type of airway, scored gastric distention 0-10 at insertion of the laparoscope and immediately before removal at the end of the surgical procedure.

RESULTS

Incidence and degree of change in gastric distension were similar in both groups. Ventilation parameters during insufflation (mean +/- SD) for LMA and ETT were: S(P)O2 98 +/- I vs 98 +/- I, P(ET)CO2 38 +/- 4 vs 36 +/- 4 mm Hg and airway pressure 21 +/- 4 vs 23 +/- 3 cm water.

CONCLUSION

Positive pressure ventilation with a correctly placed LMA-Classic of appropriate size permits adequate pulmonary ventilation. Gastric distension occurs with equal frequency with either airway device.

The Woolley and Roe case

Albert Woolley and Cecil Roe were healthy, middle-aged men who became paraplegic after spinal anaesthesia for minor surgery at the Chesterfield Royal Hospital in 1947. The spinal anaesthetics were given by the same anaesthetist, Dr Malcolm Graham, using the same drug on the same day at the same hospital. The outcome for the patients and their families was devastating, as it was for the use of spinal anaesthesia in the UK. At the trial 6 yr later, and against the opinion of leading neurologists, the judge accepted Professor Macintosh's suggestion that phenol, in which the ampoules of local anaesthetic had been immersed, had contaminated the local anaesthetic through invisible cracks. In an interview 30 yr after the verdict, Dr Graham believed tha the tragedy was caused by contamination of the spinal needles or syringes during the sterilization process. The subsequent explanation that, on the day in question, descaling liquid in the sterilizing pan had not been replaced by water, supported his belief and finally offered a credible explanation. We review the Woolley and Roe case, the status of spinal anaesthesia before and after 1947, and the relevant medico-legal judgments in claims for negligence in the early days of the National Health Service.

The intubating laryngeal mask airway in failed fibreoptic intubation

PURPOSE

Prediction of difficult tracheal intubation is not always reliable and management with fibreoptic intubation is not always successful. We describe two cases in which blind intubation through the intubating laryngeal mask airway (ILMA FasTrach) succeeded after fibreoptic intubation failed.

CLINICAL FEATURES

The first patient, a 50 yr old man, was scheduled for elective craniotomy for intracerebral tumour. Difficulty with intubation was not anticipated. Manual ventilation was easily performed following induction of general anesthesia, but direct laryngoscopy revealed only the tip of the epiglottis. Intubation attempts with a styletted 8.0 mm endotracheal tube and with the fibreoptic bronchoscope were unsuccessful. A #5 FasTrach was inserted through which a flexible armored cuffed 8.0 mm silicone tube passed into the trachea at the first attempt. The second patient, a 43 yr old man, presented with limited mouth opening, swelling of the right submandibular gland that extended into the retropharynx and tracheal deviation to the left. He was scheduled for urgent tracheostomy. Attempted awake fibreoptic orotracheal intubation under topical anesthesia showed gross swelling of the pharyngeal tissues and only fleeting views of the vocal cords. A #4 FasTrach was easily inserted, a clear airway obtained and a cuffed 8.0 mm silicone tube passed into the trachea at the first attempt.

CONCLUSION

The FasTrach may facilitate blind tracheal intubation when fibreoptic intubation is unsuccessful.

International, multicentre, placebo-controlled study to evaluate the effectiveness of ondansetron vs. metoclopramide in the prevention of post-operative nausea and vomiting

Ondansetron 4 mg was compared with metoclopramide 10 mg for prevention of post-operative nausea and emesis in in-patients undergoing major gynaecological surgery in this double-blind, randomized, placebo-controlled, multicentre study. A total of 1044 patients received a single intravenous (i.v.) injection of study medication immediately before induction of anaesthesia. Nausea and emesis were assessed over the 24 h post-operative period. Significantly more patients who received ondansetron experienced no emetic episodes (44%) compared with those who received metoclopramide (37%, P = 0.049) or placebo (25%, P < 0.001). No nausea was experienced by significantly more patients who received ondansetron (32%) than with patients who received metoclopramide (24%, P = 0.009) or placebo (16%, P < 0.001). In addition, fewer emetic episodes, less severe nausea and a reduced need for rescue antiemetics were also observed with ondansetron (P < 0.05 vs. metoclopramide and placebo). Metoclopramide and placebo-treated patients were also 1.5 times (95% Cl 1.5-4.2) and 2.5 times (95% Cl 1.1-2.0) more likely, respectively, to experience nausea post-operatively. Overall, ondansetron was the most effective antiemetic in this patient population.

Laryngeal mask airway with mouth opening less than 20 mm

We describe the use of a laryngeal mask airway in three adult patients whose mouth opening varied from 12 mm to 18 mm. The first patient's incisal opening was 12 mm. His airway was otherwise normal and the standard laryngeal mask was used as the definitive airway for the 90 min revision of facial scars and bone graft to mandible. The second patient, who had an incisal opening of 18 mm, was scheduled for posterior fossa craniotomy. She adamantly refused awake fibreoptic tracheal intubation. Following induction of general anaesthesia, a standard laryngeal mask was inserted and, through this, fibreoptic intubation was performed. The third patient, in addition to a mouth opening of only 18 mm, had limited neck movement from previous flap reconstruction following mandibulectomy, hemiglossectomy and radical neck dissection. For three more reconstructive head and neck procedures that ranged from 90 min to nine hours, the flexible reinforced laryngeal mask was inserted under topical anaesthesia and its correct position confirmed by fibreoptic laryngoscopy before induction of general anaesthesia. Maintenance of anaesthesia in all cases was uneventful and there were no postoperative complications.

Simple narcotic kits for controlled-substance dispensing and accountability

Operating rooms require a storage, dispensing and accounting system for restricted drugs which satisfies narcotics control authorities and is compatible with efficient care of patients. We describe narcotic kits containing fentanyl-morphine-midazolam, alfentanil-midazolam and sufentanil-midazolam, for general operating rooms, and two kits with larger quantities of fentanyl and sufentanil for cardiac operating rooms. The container for each kit is a video cassette holder which has a foam-rubber liner with sculpted depressions for each ampoule. Sealed kits are delivered each morning from pharmacy to the locked narcotics cupboard in the recovery room. On request, the recovery room nurse unlocks the cupboard and the anaesthetist signs out the required kit(s) for the day. A drug utilization form is enclosed with each kit, on which the anaesthetist records the amount of drug administered to each patient, and before returning the kit to the locked narcotics cupboard, the total amount of each drug used, discarded, and returned. Used kits are collected the following morning by a pharmacy technician who reconciles the contents and drug form of each kit. More than 40 staff anaesthetists and a similar number of residents have used the system for seven years, during which time 130,000 patients have passed through the operating rooms. Detection of one case of drug diversion by a staff anaesthetist was made partly by the control system, but mainly by behavioural changes. The system is simple, inexpensive, and effective and has been well received by the departments of pharmacy, anaesthesia, and nursing.

Use of refractometry to identify opioid-containing solutions

The purpose of this laboratory study was to assess the value of refractometry in identifying the contents of a variety of opioid-containing solutions. A hand-held refractometer was used to document the refraction produced by the undiluted contents of alfentanil, fentanyl, morphine, sufentanil ampoules and by solutions of Ringer's lactate, 0.9% saline, 3.3% dextrose in 0.3% saline, and distilled water. Each opioid was then serially diluted in serial 1:2, 1:4, and 1:8 dilutions in each of these solutions and the refractions of each determined. Based on this information, blinded identification of various diluted opioid solutions was attempted. Refractometer values for undiluted fentanyl and sufentanil were identical with those for distilled water. Those for undiluted alfentanil and morphine were almost identical with each other and with 1:2 and 1:4 dilutions of either drug in Ringer's lactate or 0.9% saline. We conclude that refractometry is an unreliable screening method to detect tampering with opioid solutions.

Anaesthesia services and the education of anaesthetists in Nepal: a model for sustainable development?

In 1985 the University of Calgary in Canada and Tribhuvan University in Kathmandu, Nepal Jointly established the Diploma in Anaesthesiology (DA) programme in Nepal. To evaluate the impact of the DA Programme and provide a data base for long-term planning we conducted a national survey in 1992. We sought to describe anaesthesia manpower and workloads, and to make an inventory of facilities, equipment, and supplies in different sized hospitals. Twenty-seven hospitals providing surgical services were included, nine inside and 18 outside the Kathmandu valley. Seventeen of the 21 respondent hospitals had at least one specialist anaesthetist. The results identify both strengths and weaknesses in Nepal's anaesthesia services and provide important guidelines for planning. When the DA course was launched there were only seven specialist anaesthetists in Nepal. The shortage of anaesthetists was an important factor limiting surgical services, and after DA graduates were posted to zonal (50 bed) and regional (150-200 bed) hospitals the surgical case loads doubled. There are now about 40 specialist anaesthetists in the country, of which half are DA graduates, but many hospitals have only one anaesthetist. That isolation, plus lack of continuing education (CME), are important factors threatening quality of care. Recognizing the singular role of the DA programme in alleviating Nepal's shortage of anaesthetists, we conclude that it should be renewed and strengthened to meet the needs of the next decade. Techniques commonly used at the zonal level: regional, draw-over, and total IV anaesthesia, should be stressed. At the same time fresh initiatives are required in CME and higher education for the renewal of teaching staff.(ABSTRACT TRUNCATED AT 250 WORDS)

Informed consent for clinical anaesthesia research

Most surgical patients are first seen by an anaesthetist after admission to hospital, either the evening before or on the day of surgery. Some medical ethicists believe that an approach by an anaesthesia researcher made after admission is unethical because the hospital itself is a coercive environment, and patients have insufficient time for reflection or consultation. Others believe that an approach prior to admission may be an invasion of the patient's privacy and confidentiality. The implications of these views for anaesthesia researchers may not be apparent to research ethics boards (REBs). To determine current practice, a questionnaire concerning the membership and function of REBs and the time of obtaining informed consent was sent to each research representative of the 16 Canadian university departments of anaesthesia. Membership of REBS was similar, but not identical, in all centres. Most representation was from medical disciplines. Consent was generally obtained following the patient's admission to hospital. In one centre, the REB always requested informed consent to be obtained before the patient's admission to the hospital. Surgeons had no involvement with consent for anaesthesia research in 14 centres while in the other two they gave permission for their patients to be studied and informed patients of the potential approach by anaesthesia researchers. We conclude that it is ethically acceptable to obtain informed consent for most low-risk clinical anaesthesia research after the patient's admission to hospital.

Comparison of plain with pH-adjusted bupivacaine with hyaluronidase for peribulbar block

Fifty patients scheduled for cataract surgery under peribulbar block were randomised to receive either plain (pH 5.4) or pH-adjusted (pH 6.8 range 6.7-6.9) 0.75% bupivacaine. Hyaluronidase was added to both solutions prior to peribulbar block. The time of onset of akinesia of the globe and the need for supplementary injections were recorded by an independent observer. Patients who returned for surgery to the second eye received the alternative local anaesthetic solution for the second peribulbar block. The relative efficacy of the different anaesthetic solutions was compared in patients who underwent unilateral surgery (Group A, n = 50). In 12 patients (Group B) who underwent bilateral surgery, direct comparisons between eyes in the same patient were possible. In both groups of patients, eyes receiving peribulbar block with the pH-adjusted solution showed a shorter time to partial akinesia of the globe (P less than 0.05). However, there was no difference between the solutions in the time to complete akinesia of the globe, but the number of supplementary injections required for an effective block with the pH-adjusted solution was increased. Onset time to akinesia of the lateral and superior rectus muscles was shortened in patients receiving the pH-adjusted solution but there were minimal effects on the medial and inferior recti.

Vomiting and aspiration pneumonitis with the laryngeal mask airway

We report a case of severe aspiration pneumonitis in the dependent lung of a 74-yr-old man following Austin-Moore arthroplasty. A laryngeal mask airway provided a clear airway until anaesthesia became too light during manipulation of the fractured femoral head. Active vomiting occurred and gastric contents were "reflected" back into the trachea. Tracheal intubation and suction were immediately performed but the patient required postoperative ventilatory and inotropic support for three days.

Gastric fluid volume and pH in elective patients following unrestricted oral fluid until three hours before surgery

This clinical study was designed to assess the results of new preoperative fasting guidelines in which patients are instructed that they must not eat any solid food after midnight, but that they may drink unrestricted amounts of clear fluid until three hours before their scheduled time of surgery. We studied 199 healthy, elective surgical inpatients aged 18-70 yr to determine whether there was any correlation between the ingestion interval or the volume of fluid ingested, with the volume and pH of residual gastric fluid at induction of anaesthesia. Pregnant patients, and those with gastric disorders or who were taking medications that affect gastric motility or secretion, were excluded. Either no premedication was given, or oral diazepam 5-15 mg was given 90 min preoperatively. Of the 199 patients, 105 ingested 50-1200 ml on the morning of surgery. The ingestion-induction interval was less than three hours in 12 patients whose actual surgery time was ahead of schedule. The remaining 94 patients did not drink because they were scheduled for surgery before 11:00 (n = 51), they did not want to drink (n = 24), or they were advised not to drink by their nurse or surgeon (n = 16). Following induction of anaesthesia, gastric fluid was aspirated through a #18 Salem sump orogastric tube, the volume was recorded and pH was measured with a calibrated pH meter. Patients were divided retrospectively into four groups (in three of which patients ingested fluid) according to the ingestion-induction interval (1.3-3.0 hr, 3.1-5.0 hr, 5.1-8.0 hr, and nothing by mouth after midnight).(ABSTRACT TRUNCATED AT 250 WORDS)

Anaesthesia training and development in Nepal 1985-1990

In 1985 a diploma program in anaesthesia was established in Kathmandu, Nepal, as a joint venture between the Institute of Medicine in Kathmandu and the University of Calgary. Development of the program and of the specialty in the capital city of Kathmandu was continuously documented during the next five years by local and visiting faculty. In 1990 teams of two Nepali and one Canadian anaesthetist also conducted a survey of each of the seven 50-100 bed zonal hospitals which did not previously have a trained anaesthetist and which are now staffed by graduates of the diploma program. In 1985 Nepal, with a population of 16 million, had seven trained Nepali anaesthetists all of whom worked in two hospitals in Kathmandu. By the end of 1989, 19 physicians had graduated. Seven of these continue to work in Kathmandu hospitals, nine work in zonal hospitals throughout the country and two are taking higher anaesthesia training in the United Kingdom. Additional Nepali anaesthetists have returned from training abroad, and the Society of Anaesthesiologists of Nepal, which joined the World Federation of Societies of Anaesthesiologists in 1988, now has 34 members. An annual anaesthesiology symposium is held, and weekly clinical meetings are organized in the major hospitals in Kathmandu. Anaesthetists who work in the zonal hospitals have limited supplies of drugs and equipment and opportunities for continuing medical education are virtually nonexistent.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastric fluid volume and pH in elective surgical patients: triple prophylaxis is not superior to ranitidine alone

The effect of oral ranitidine alone was compared with sequentially administered ranitidine, metoclopramide, and sodium citrate on gastric fluid volume and pH in 196 healthy, elective surgical inpatients, each of whom was randomly assigned to one of four groups. Patients in all groups received oral ranitidine 150 mg 2-3 hr before the scheduled time of surgery. Those in Group 1 also received oral metoclopramide 10 mg one hour before surgery, and sodium citrate 0.3 M 30 ml on call to the operating room; Group 2 received sodium citrate but no metoclopramide; Group 3 received metoclopramide but no sodium citrate; Group 4 received ranitidine alone. Following induction of anaesthesia a #18 Salem sump tube was passed into the stomach and all available gastric fluid was aspirated. Volumes were recorded and pH measured. In all groups mean pH was greater than 5.8, although at least one patient in each group had pH less than 2.5. Mean volumes were significantly greater in patients who received citrate (Groups 1 and 2: 22 and 19 ml) than in those in those who did not (Groups 3 and 4: 10 and 8 ml). One patient in Group 2 and one in Group 3 had pH less than 2.5 with volume greater than 25 ml. Our results do not demonstrate any advantage of double or triple prophylaxis over ranitidine alone. The practical difficulty of correctly administering two or even three medications, each at different but exact preoperative intervals, is emphasized.

The Wood Library-Museum's 1858 edition of John Snow's On chloroform and other anaesthetics

The original 1858 edition of John Snow's On Chloroform and Other Anaesthetics, from which came the Wood Library-Museum of Anesthesiology reprints in 1971 and 1989, was donated to the Wood Library-Museum by Ralph Waters of Madison, Wisconsin, in 1967. The book contains a message of appreciation to Waters, dated October 1937, with the signatures of J. Blomfield, Charles King, and R.R. Macintosh as representatives of anesthesiology in England. Correspondence exists in the archives of the University of Wisconsin-Madison between Macintosh, Professor of Anaesthetics in Oxford, and Waters, Associate Professor in Madison. This reveals that Waters, during his visit to England in 1936, inspired British anesthetists to discover more of Snow's early contributions to anesthesiology, even though Waters himself did not possess On Chloroform and Other Anaesthetics. King, a manufacturer of anesthetic equipment, found a copy in the hands of Blomfield, an anesthetist at St. George's Hospital, London, where John Snow had worked. It was this copy that they presented to Waters, and that was delivered to Waters by hand when Waters' resident, Ivan Taylor, returned from Oxford to Madison. Blomfield's ownership of the book, in addition to his position as president of the Association of Anaesthetists of Great Britain and Ireland, explains why the inscription is in his handwriting.

The laryngeal mask airway: clinical appraisal in 250 patients

The laryngeal mask airway consists of a tubular oropharyngeal airway to the distal end of which is sealed a silicone laryngeal mask with an inflatable rim which provides an airtight seal around the larynx. It provided a clear airway in 238 of 250 elective and emergency non-obstetrical patients for a wide variety of surgical procedures, ranging from minor gynaecological and urological procedures to major abdominal and orthopaedic surgery with either spontaneous respiration or intermittent positive pressure ventilation. Anaesthetic techniques and drugs were similar to those which would have been used for the same procedures if face-mask or tracheal intubation had been employed. Blind insertion of the laryngeal mask airway was successful at the first attempt in 187 patients, some manipulation was required in 61 patients, and insertion was impossible in two patients, each of whom had a small mouth. In ten patients tracheal intubation was required because of airway obstruction or a large gas leak. The LM airway does not require laryngoscopy for its insertion, it relieves the anaesthetist's hands from holding a face-mask, it cannot be misplaced in the oesophagus, and it is well tolerated during emergence from anaesthesia.

Volume and acidity of residual gastric fluid after oral fluid ingestion before elective ambulatory surgery

We studied 211 unselected, healthy, adult patients scheduled to undergo elective ambulatory surgery to determine whether the volume or pH of gastric fluid at induction of anesthesia is correlated with the duration of the preoperative fluid fast. Patients were instructed that they must not eat any solid food after midnight but that they were permitted to drink 150 ml of tea, coffee, apple juice or water until 3 hours before their scheduled time of surgery. Patients with gastric disorders and those taking medications that affect gastric motility or secretion were excluded. No premedicant drugs were given. Following induction of general anesthesia the gastric fluid was aspirated through an orogastric tube, its volume recorded and its pH measured with a calibrated pH meter. The patients were retrospectively assigned to one of four groups according to the interval from last fluid ingestion until induction of anesthesia (less than 3 hours, 3 to 4.9 hours, 5 to 8 hours and nothing after midnight). The mean values and extremes for gastric fluid volume and pH were similar in the four groups. We conclude that healthy patients should be allowed to ingest fluid until 3 hours before elective ambulatory surgery.

Effect of oral liquids and ranitidine on gastric fluid volume and pH in children undergoing outpatient surgery

Eighty-eight children (mean age 5.6 yr, range 1-14 yr) about to undergo elective outpatient surgery were randomly assigned to four groups. All children were given phenolsulfonphthalein (PSP) orally 2-3 h before the scheduled time of surgery as a marker dye to assess gastric emptying. Immediately after receiving PSP they were given: group A--liquids, up to 5 ml/kg + placebo (glucose water 0.2 ml/kg); group B--liquids, up to 5 ml/kg + ranitidine 2 mg/kg in glucose water 0.2 ml/kg; group C--placebo only; group D--ranitidine only. Gastric contents were aspirated after induction of anesthesia. Mean volume (range) in ml/kg of aspirated gastric fluid in each group was: group A--0.34 (0-1.0); group B--0.17 (0.07); group C--0.25 (0-1.1); group D--0.16 (0-0.6). The pH mean (range) value was: group A--1.83 (0.9-3.6); group B--4.76 (2.0-7.7); group C--2.10 (1.2-4.1); group D--3.97 (1.3-7.3). PSP could not be detected in the gastric samples from children in whom the ingestion-sampling interval was more than 2.25 h. In comparison with prolonged starvation, administration of oral liquids without ranitidine 2-3 h preoperatively did not produce a significant increase in mean volume of gastric aspirate, and there was no increase in the number of patients with gastric aspirate greater than 0.4 ml/kg. Administration of ranitidine with or without fluids resulted in a decrease in both volume and acidity of gastric contents.