Inflatable splints: do they cause tissue ischaemia?

A sequential compression mechanical pump to prevent hypotension during elective cesarean section under spinal anesthesia

BACKGROUND

Spinal anesthesia is a standard technique for cesarean section but can cause hypotension which may be related to venous pooling secondary to progesterone-induced decreases in vascular tone. This study investigated the use of a sequential compression mechanical pump with thigh-high sleeves with compression cycles timed to venous refilling. We hypothesized that this would recruit pooled venous blood from the lower limbs, maintain the central blood volume and thus decrease the incidence of hypotension.

METHODS

One hundred parturients scheduled for elective cesarean section under spinal anesthesia were recruited and randomly assigned to use of either a mechanical pump (Group M) or control (Group C). A standardized protocol for co-hydration and anesthesia was followed. Hypotension, defined as a decrease in systolic blood pressure by >20% from baseline, was treated with 6-mg boluses of intravenous ephedrine. The incidence of hypotension was defined as the primary outcome. Median ephedrine requirement was taken as a measure of the severity of hypotension.

RESULTS

Hypotension occurred in 12 of 47 (25.5%) patients in Group M compared to 27 of 45 (60%) in Group C (P=0.001). The median [range] ephedrine dose was greater in Group C (12 [0-24]mg) compared to Group M (0 [0-12]mg) (P<0.001). There was no difference between groups in the time to onset of hypotension.

CONCLUSION

The use of a sequential compression mechanical pump that detects venous refilling and cycles accordingly, reduced the incidence and severity of hypotension after spinal anesthesia for cesarean section.

A review of emergency equipment carried and procedures performed by UK front line paramedics on paediatric patients

OBJECTIVES

In 1997 a review of paramedic practice upon adult patients in the UK found many inconsistencies and deficiencies in basic care. A follow up review in 2002 identified widespread improvement in provision of equipment and skills to provide basic and advanced life support.Paediatric care was not assessed in either review. The authors conducted this study to identify current standards of care in paediatric paramedic practice and areas of potential improvement.

METHOD

A questionnaire designed to determine what equipment and skills were available to paramedics for the management of common or serious paediatric emergencies was sent to chief executives of the 32 NHS Ambulance Trusts in England and Wales.

RESULTS

The trend of expanding and standardising practice among adult patients has not extended to paediatric practice despite national guidelines from the Joint Royal Colleges Ambulance Liaison Committee (JRCALC). Furthermore there are some serious failings in the provision of care and skills. Many Trusts have not adopted JRCALC guidelines for the management of life threatening paediatric emergencies such as asthma, meningitis, and fluid replacement in hypovolaemia.

CONCLUSIONS

Ambulance Trusts not meeting standards set out in the JRCALC guidelines must address their areas of deficiency. Failure to do so endangers children's lives and leaves Trusts open to criticism.

A review of emergency equipment carried and procedures performed by UK front line paramedics

OBJECTIVES

To assess which items of resuscitation equipment are carried on United Kingdom (UK) front line ambulances and what procedures paramedics are able to perform. To compare these findings with those of a previous survey in 1997.

METHOD

Postal survey to the chief executives of all the UK ambulance services and direct comparison with the data from 1997.

RESULTS

Nasopharyngeal airway usage (NPA) has increased (21-55%) and the laryngeal mask airway (LMA) (from 10 to 26%). No services employ the Combitube. 94% of services use a Hudson type trauma mask (increase of 17%). One service no longer allows its paramedics to deliver 12-15 l of oxygen. 68% of trust paramedics can perform needle thoracocentesis (increase of 35%). No paramedics perform chest drain insertion. All services have 14G intravenous cannulae available and 45% carry the intraosseous needle (increase of 30%). No services employ the MAST suit. There is an increase by 29% in the use of crystalloids and a decrease in the use of colloids of 22%. 23% of fluid resuscitation protocols are based upon the principles of hypotensive resuscitation. Spinal boards and extrication devices are used by 97% of services. The use of inflatable splints has decreased (38-23%). There has been a minor increase in the use of traction splints to 74% of services. The use of Entonox is universal. Nalbuphine (Nubain) is the most widely used opioid. The use of morphine/diamorphine has doubled to 10% with a further 26% to introduce their use. 29% of services have equipped some vehicles with automatic external defibrillators.

CONCLUSIONS

The equipment available to UK paramedics and procedures that they may perform continues to expand. There are still variations in the basic management of airway, breathing and circulation care and only some services are keeping up to date with current medical thinking, for example the increasing use of crystalloids and hypotensive resuscitation. It remains to be seen whether the widespread use of Nalbuphine as a first line analgesic may decrease as the use of natural strong opiates becomes more widespread.

The effects of simulated Bier block IVRA on intracompartmental tissue pressure

BACKGROUND

Intravenous regional anesthesia (IVRA) is a useful anesthetic method for closed reduction of fractures. However, IVRA has been associated with an increased incidence of compartment syndrome when treating tibial shaft fractures. The purpose of this study was to measure changes in anterior leg compartment pressures during simulated IVRA.

METHODS

A volunteer study was performed. An indwelling catheter placed in a consistent location between subjects was used to measure tissue pressure. A vinyl leg splint was used for exsanguination followed by thigh tourniquet inflation (300 mmHg). Normal saline (1.5 mL/kg) was injected through the greater saphenous vein (1.0 mL/s). Pressure measurements were obtained before and after tourniquet inflation, at 10 mL increments during saline injection, and intermittently after volume injection with the tourniquet inflated, then deflated.

RESULTS

There was no significant difference in tissue pressure before (2.4 +/- 2.2 mmHg) and after (4.3 +/- 3.7 mmHg) tourniquet inflation (P = 0.11). No significant difference in tissue pressure were found as a function of injected volume (P = 0.62), as a function of time following saline injection during tourniquet inflation (P = 0.08), and after tourniquet deflation (P = 0.16).

CONCLUSIONS

We conclude that in the normal atraumatic limb, simulated IVRA using normal saline does not increase tissue pressure within the anterior leg compartment.

Effects of Cold and Compression on Edema

In brief: A 40-minute cooling period was used to treat artificially induced acute inflammatory reactions in human tissue. Results showed no significant change in the volume of the inflammatory reaction at one hour, though a transient attenuation during the first 15 minutes was detected. The addition of mild pressure (10 mm Hg) to mild cooling (range, 15° to 25° C) produced a highly significant reduction in swelling from 15 minutes onward, This effect was sustained as long as swelling was detectable. Pressure alone (20 mm Hg) had a nonsignificant effect. The authors compare two cooling devices, an inflatable cooling cuff and an evaporative bandage, which were both found to be effective. The authors suggest that these devices could be used more routinely in emergency medicine.