Handling injectable medications in anaesthesia: Guidelines from the Association of Anaesthetists

Peri-operative medication safety is complex. Avoidance of medication errors is both system- and practitioner-based, and many departments within the hospital contribute to safe and effective systems. For the individual anaesthetist, drawing up, labelling and then the correct administration of medications are key components in a patient's peri-operative journey. These guidelines aim to provide pragmatic safety steps for the practitioner and other individuals within the operative environment, as well as short- to long-term goals for development of a collaborative approach to reducing errors. The aim is that they will be used as a basis for instilling good practice.

An audit of the effect of case selection on compliance with a 30-minute audit standard for decision-to-delivery interval at category 1 caesarean section

BACKGROUND

Our hospital has an audit standard that ≥90% of women having category 1 (emergency) caesarean section should have a decision-to-delivery interval (DDI) ≤30 min. This audit aimed to identify potential influences of case selection on compliance.

METHODS

A prospective audit of category 1 caesarean section recorded urgency at time of decision for surgery and any urgency changes, as well as whether caesarean section followed failed operative vaginal delivery in the operating theatre.

RESULTS

Among 405 women, 158 women had failed operative vaginal delivery in the operating theatre followed by caesarean section, 247 had the delivery decision made in the labour room, 43 had a change in urgency. Depending on case inclusion, the proportion of women with DDI room, and 43 >30 min ranged between 8.3% (30/362; no urgency change, failed operative vaginal delivery included) and 21.9% (54/247; change in urgency, failed operative vaginal delivery excluded). The proportion of women with a DDI >30 min was 18.5% (42/227) if the decision for category 1 caesarean section was made in the labour delivery room (excluding cases of failed operative vaginal delivery).

CONCLUSIONS

Compliance with an audit standard for (DDI) at category 1 caesarean section is markedly influenced by the inclusion criteria. For comparability with other publications, it is suggested urgency should be reported as that applied at the point of decision for caesarean section, however, category 1 caesarean section cases following failed operative vaginal delivery in the operating theatre should be identified and reported separately.

Defining the decision-to-delivery interval at caesarean section: narrative literature review and proposal for standardisation

The decision-to-delivery interval is a widely used term at non-elective caesarean section. While the definition may appear self-evident, there is no universally agreed consensus about when this period begins and ends. We reviewed the literature for original research utilising the terms 'decision-to-delivery', 'decision-to-incision' or 'incision-to-delivery' and examined definitions used for decision, delivery, incision, as well as any additional time intervals that were assessed. Our analysis demonstrated an inconsistent non-standardised approach to defining these intervals, which might have clinical practice and medicolegal ramifications. We propose that the decision-to-delivery interval should be defined as follows: the interval between the time at which the senior obstetrician makes the decision that a caesarean section is required and the time at which the fetus (or first fetus in the case of multiples) is delivered. The decision time should ideally be recorded contemporaneously in the medical notes or partogram.

Selection of baseline blood pressure to guide management of hypotension during spinal anaesthesia for caesarean section

INTRODUCTION

Recommendations on vasopressor management during caesarean section under spinal anaesthesia suggest maintaining systolic arterial pressure ≥90% of an accurately measured baseline value. The baseline is often taken as the first reading in the operating room. We hypothesise that this reading may not reflect an accurate baseline value.

METHODS

A retrospective case note review of 300 non-hypertensive women undergoing caesarean section with neuraxial anaesthesia, including spinal anaesthesia for elective delivery (n=100), and spinal (n=100) and epidural top-up anaesthesia (n=100) for emergency delivery. Systolic arterial pressure values recorded at various time points between the last antenatal visit and the first blood pressure value recorded in the operating room were compared.

RESULTS

There was a stepwise and significant increase in systolic arterial pressure over three time points (last antenatal clinic, morning of surgery, operating room) before elective caesarean section (all P <0.001). In women having emergency caesarean under spinal anaesthesia, a stepwise increase over four time points (last antenatal clinic, first reading in labour, final reading in labour, operating room) was observed. A similar trend was seen over these time points for women having emergency caesarean under epidural top-up, although the systolic blood pressure did not rise during labour.

CONCLUSIONS

Using the initial blood pressure reading in the operating room as the baseline value may lead to unnecessary vasopressor use and hypertension. Prospective research is required to clarify which reading represents the most accurate baseline to maintain homeostasis and reduce the hypotensive sequelae of neuraxial anaesthesia for both the mother and fetus.

Serum fibroblastic growth factor 23 in acute Sarcoidosis and normal kidney function

BACKGROUND

Serum fibroblastic growth factor (FGF) 23 has recently been established as a major physiological regulator of phosphate homeostasis and may have a causal role in adverse cardiovascular and bone outcomes. However its role in states of disordered phosphate homeostasis and normal kidney function is as yet under characterised.

AIMS

To investigate whether this biomarker of vascular calcification and adverse bone outcomes is detectable in patients with sarcoidosis.

DESIGN

We conducted a cross sectional study on a convenience sample of patients presenting with acute sarcoidosis to a respiratory tertiary referral unit.

METHODS

We set out to systematically examine the characteristics and determinants of serum FGF-23 in patients presenting with acute sarcoidosis.

RESULTS

We studied 39 patients, 26 were male. Mean (SD) age was 33 (9.6) years. 15.4% of patients had a serum level of FGF-23 ≥ 9.9 pg/mL. The remaining 84.6% of patients had a serum FGF-23 < 9.9 pg/mL. Those with a detectable serum FGF-23 had a significantly higher serum calcium (P = 0.007), and lower serum iPTH (P<0.001). Serum phosphate and 25-hydroxyvitamin D were not statistically significantly different between groups (P=0.25 and P=0.83). The proportion of patients with stage II disease on CXR was higher in those with a detectable FGF-23 (P<0.001).

CONCLUSIONS

Serum FGF-23 was below the level of detection in the majority of this cohort of patients presenting with acute sarcoidosis. A detectable serum FGF-23 was associated with a higher serum calcium and lower serum iPTH.

Obstetric Anaesthetists' Association and Difficult Airway Society guidelines for the management of difficult and failed tracheal intubation in obstetrics

The Obstetric Anaesthetists' Association and Difficult Airway Society have developed the first national obstetric guidelines for the safe management of difficult and failed tracheal intubation during general anaesthesia. They comprise four algorithms and two tables. A master algorithm provides an overview. Algorithm 1 gives a framework on how to optimise a safe general anaesthetic technique in the obstetric patient, and emphasises: planning and multidisciplinary communication; how to prevent the rapid oxygen desaturation seen in pregnant women by advocating nasal oxygenation and mask ventilation immediately after induction; limiting intubation attempts to two; and consideration of early release of cricoid pressure if difficulties are encountered. Algorithm 2 summarises the management after declaring failed tracheal intubation with clear decision points, and encourages early insertion of a (preferably second-generation) supraglottic airway device if appropriate. Algorithm 3 covers the management of the 'can't intubate, can't oxygenate' situation and emergency front-of-neck airway access, including the necessity for timely perimortem caesarean section if maternal oxygenation cannot be achieved. Table 1 gives a structure for assessing the individual factors relevant in the decision to awaken or proceed should intubation fail, which include: urgency related to maternal or fetal factors; seniority of the anaesthetist; obesity of the patient; surgical complexity; aspiration risk; potential difficulty with provision of alternative anaesthesia; and post-induction airway device and airway patency. This decision should be considered by the team in advance of performing a general anaesthetic to make a provisional plan should failed intubation occur. The table is also intended to be used as a teaching tool to facilitate discussion and learning regarding the complex nature of decision-making when faced with a failed intubation. Table 2 gives practical considerations of how to awaken or proceed with surgery. The background paper covers recommendations on drugs, new equipment, teaching and training.

Assessment of a modified four-category classification of urgency of caesarean section

A four-category urgency classification for caesarean section (CS) based on clinical definitions was introduced in 2000. However, clinical application remains inconsistent. We proposed that modification of the wording of these definitions might improve consistency of assignment of urgency. A total of 349 maternity professionals applied an urgency category to 10 hypothetical cases of CS, using either the original or a modified classification. There was a supplementary question relating to urgency category in relation to the 30 minute decision-to-delivery time standard. The commonest urgency categories applied to the cases by the respondents were: Category 1: cord prolapse, significant placental abruption, maternal cardiorespiratory distress; Category 2: late fetal heart rate decelerations, CS pre-booked to avoid vaginal delivery but woman presents in advanced labour, bleeding placenta praevia without hypovolaemia, failed instrumental delivery with no fetal compromise; Category 3: deteriorating but compensated maternal medical condition; Category 4: operation at short notice but no clinical urgency. Consistency of responses in individual cases varied from 0.92 down to 0.55. Some 66% of respondents believe that only Category 1 cases should be included in a 30 minute decision-to-delivery time standard, whereas 34% would include Category 2 as well as Category 1 in this standard. The consistency of responses did not differ between the original and modified urgency classifications. Inter-rater reliability was better when comparing the answers from obstetricians compared with anaesthetists or midwives. This study found that the proposed modifications did not improve the consistency of application, and that any changes to the current classification should not be introduced without thorough investigation.

A prospective audit of regional anaesthesia failure in 5080 Caesarean sections

Anaesthesia for Caesarean section was audited over a 5 year period: 5080 cases were performed using spinal 63%, epidural top-up 26%, combined spinal-epidural 5% and primary general anaesthesia 5%. The rate of general anaesthesia conversion of regional anaesthesia was 0.8% for elective and 4.9% for emergency Caesarean section compared to Royal College of Anaesthetists targets of 1% and 3%. The rate of conversion of regional to general anaesthesia in category 1 Caesarean section was 20%. A total of 8% of women had general anaesthesia when both primary general and conversion of regional anaesthesia were combined. The rate of failure to achieve a pain-free operation was 6% with spinals, 24% with epidural top-up and 18% with combined spinal-epidural. Besides the type of anaesthesia and operative urgency, other factors associated with pre-operative failure of regional anaesthesia included body mass index, no previous Caesareans, and indication for Caesarean of acute fetal distress or maternal medical condition. Inadequacy of pre-operative anaesthetic block and duration of surgery were important risk factors for intra-operative failure. For spinal anaesthesia, use of a spinal opioid was associated with less pre-operative failure. For epidural top-up anaesthesia, lower epidural top-up volume was associated with less pre-operative failure, and use of adrenaline was associated with both less pre-operative and intra-operative failure. The rate of serious adverse incidents was 1 : 126 with general anaesthesia and 1 : 501 with regional anaesthesia.

Effect of blood pressure instrument and cuff side on blood pressure reading in pregnant women in the lateral recumbent position

BACKGROUND

Hydrostatic forces affect non-invasive blood pressure measurement in the lateral position. This study assessed the extent of this effect with the mercury column sphygmomanometer and Dinamap oscillometric instrument as well as different recommendations for comparing supine and lateral blood pressure measurements.

METHOD

Thirty-two term pregnant women were studied in the antenatal clinic. Blood pressure was recorded from both arms in the right lateral and supine recumbent positions, using the sphygmomanometer and Dinamap.

RESULTS

Blood pressure in the uppermost arm while lateral was lower than supine by a mean 10 mmHg or more. Systolic, mean and diastolic pressures in the dependent arm while lateral were higher than supine by a mean (SD) 3.1 (6.8)mmHg, 5.6 (6.8)mmHg, and 6.9 (8.7)mmHg using the sphygmomanometer and 3.8 (8.1)mmHg, 3.2 (7.1)mmHg, and 1.9 (5.3)mmHg using the Dinamap. Systolic, mean and diastolic pressure values calculated as the average taken from both arms in the lateral position were lower than supine by a mean (SD) 3.5 (7.5)mmHg, 3.9 (4.7) mmHg, and 4.1 (5.8)mmHg using the sphygmomanometer and 4.6 (6.0)mmHg, 4.9 (4.4)mmHg, and 4.8 (4.4)mmHg using the Dinamap. Corresponding blood pressure readings were always higher using the Dinamap than the sphygmomanometer.

CONCLUSIONS

In normotensive non-labouring term pregnant women, the use of the dependent arm or an average blood pressure from both arms while in the lateral position will give a closer reading to supine blood pressure than the use of the uppermost arm. However, use of the dependent arm is simpler.

Obstetric epidural test doses: a survey of UK practice

BACKGROUND

With the advent of low-dose epidural analgesia in labour, the content of the test dose has once again become the subject of debate.

METHOD

A postal survey of 500 members of the Obstetric Anaesthetists' Association was conducted in 1999-2000, assessing the use of test doses during epidurals in labour and for caesarean section.

RESULTS

There was a 67% response rate. Test doses are used in labour, at elective caesarean section and before epidural top-up for emergency caesarean section, by 90%, 93% and 37%, respectively. There was large variation in both drugs and doses. During labour, doses of bupivacaine range from 3 to 20 mg and of lidocaine 15 to 90 mg. There has been a three-fold increase in the use of low-dose local anaesthetic test doses since a previous national survey in 1997. The size of local anaesthetic test doses used at caesarean section is also variable. Epinephrine is used in 5% of labour, 14% of elective and 34% of emergency caesarean sections. Signs and symptoms that are commonly sought after test doses include somatic motor block, blood pressure change, sensory effect and symptoms from systemic local anaesthetic. The effect of the test dose is usually assessed after 5 min.

CONCLUSION

There is no consensus about the nature of the ideal test dose in obstetric anaesthesia. There is a trend to use less concentrated test doses during labour. Doses that risk a high block if given spinally are still used. Epinephrine, aspiration testing and cardiovascular monitoring are uncommon.

Dose response study of subarachnoid diamorphine for analgesia after elective caesarean section

Subarachnoid diamorphine provides excellent analgesia after elective caesarean section but the optimum dose is still uncertain. We therefore investigated the effects of three regimens of subarachnoid diamorphine. Forty parturients were assigned to one of four groups. A control group received no diamorphine in their subarachnoid bupivacaine and three study groups received 0.1 mg, 0.2 mg or 0.3 mg diamorphine added to 12.5 mg hyperbaric bupivacaine 0.5% in a semi-blind randomised design study. All women received a 100 mg diclofenac suppository at the end of the caesarean section and were provided with morphine patient controlled analgesia (PCA) postoperatively. The patients were assessed for pain, morphine usage and side-effects at 2, 4, 8 and 24 h after the subarachnoid injection. Postoperative visual analogue scores for pain and PCA morphine consumption were significantly lower, and mean time to first use of morphine was significantly longer in the 0.3 mg diamorphine group. The mean (SD) dose of PCA morphine used over 24 h was 39.4 (14.7), 25.6 (16.5), 21.6 (15.9) and 3.1 (3.6) mg, and mean time to first use of morphine was 1.6 (0.5), 3.0 (1.4), 3.4 (2.4) and 14.1 (9.4) h, in the 0, 0.1 mg, 0.2 mg and 0.3 mg groups respectively. Side-effects of pruritus, nausea and vomiting were dependent on the dose of spinal diamorphine but did not require treatment in any patients. We conclude that 0.3 mg subarachnoid diamorphine provides significantly better postoperative pain relief than the smaller doses with an acceptable increase in side-effects.

100% inspired oxygen from a Hudson mask-a realistic goal?

BACKGROUND

The administration of oxygen at a high-inspired concentration is often required in medicine, particularly in resuscitation of critically ill patients. However, there is a lack of evidence-based guidance on how to achieve this using currently available apparatus. The aim of this study was to assess how maximum inspired oxygen concentrations can be delivered using existing equipment.

METHODS

Ten healthy female volunteers breathed oxygen through two types of Hudson non-rebreathing mask with reservoir bag, one with a safety vent in the mask body and the other with a valve replacing this safety vent (3-valve mask). Oxygen flow was adjusted to either 10 or 15 l min(-1) and the masks were fitted to the face either loosely or tightly. The expired oxygen concentration was measured using an oxygen analyzer.

FINDINGS

By using the Hudson non-rebreathing mask with three valves, increasing the oxygen flow to 15 l min(-1), and fitting the mask tightly to the face the average expired oxygen fraction could be raised to 0.85. This equates to an average inspired oxygen fraction of 0.97 in these subjects.

INTERPRETATION

The three simple measures mentioned above result in a significant improvement in the performance of the Hudson non-rebreathing mask. Together they allow the delivery of an inspired oxygen concentration close to maximum.

Comparison of measured and estimated angles of table tilt at Caesarean section

BACKGROUND

Lateral maternal tilt reduces aortocaval compression and the consequent cardiovascular instability.

METHODS

We measured the angle of table tilt used by 16 anaesthetists during uncomplicated, elective Caesarean section. After initiating anaesthesia, they were asked to position the patient and estimate the angle of tilt, which was then measured.

RESULTS

Almost every anaesthetist positioned the patient less than 15 degrees because they overestimated the angle of tilt. When questioned on their knowledge of the current advice for lateral tilt, 11 of the 16 anaesthetists were aware of the 15 degrees recommendation.

CONCLUSION

Estimation of the angle of table tilt is unreliable.