Evidence of malignant hyperthermia in patients administered triggering agents before malignant hyperthermia susceptibility identified: missed opportunities prior to diagnosis.

Malignant hyperthermia (MH) is a hypermetabolic disorder of skeletal muscle triggered almost exclusively by potent inhalational agents and suxamethonium. Signs of an MH reaction are non-specific and may be confused with the presentation of other problems such as sepsis and overheating of a patient. A high index of suspicion is needed to be aware of an early presentation of MH. Nine patients are presented who showed abnormal signs with an earlier anaesthetic where the possible diagnosis of an MH reaction was missed. These patients either presented later with an MH reaction, confirmed by DNA analysis and in some cases in vitro contracture testing, or were diagnosed by the identification of a causative mutation confirming MH susceptibility. The MH clinical grading scale is helpful in determining the likelihood that clinical indicators indicate a possible MH reaction. Masseter muscle rigidity is a known sign of MH, confirmed in this report by positive in vitro contracture testing and DNA analysis. Several uncommon muscle disorders have a high association with MH, and postoperative myalgia unrelated to suxamethonium can be a sign which is associated with MH. These reports emphasise the importance of a thorough family history (as the MH status was known by the family in four patients), a high index of suspicion for MH, and documentation of the possibility of MH susceptibility in the anaesthesia record.

Administration of anaesthetic triggering agents to patients tested malignant hyperthermia normal and their relatives in New Zealand: an update.

Testing for malignant hyperthermia in New Zealand involves two tests-in vitro contracture testing of excised lateral quadriceps muscle and DNA analysis. In vitro contracture testing is regarded as the gold standard in malignant hyperthermia diagnosis but several publications have questioned the reliability of a normal result. Analysis of 479 anaesthetic records in 280 patients or their descendants throughout New Zealand who had tested negative for malignant hyperthermia, demonstrated there was no evidence of malignant hyperthermia episodes in this group who had been administered anaesthetic triggering agents. A wide range of anaesthetics were used over the study period. Analysis of each anaesthetic record was undertaken using the malignant hyperthermia grading scale which determines the likelihood that an anaesthetic event represents a malignant hyperthermia episode. Confirmation of the negative results was further supported by normal DNA analysis of patients in 48% of anaesthetics. There are advantages to using inhalational agents in certain situations and although demonstrating a zero risk of a malignant hyperthermia episode is not statistically possible, evidence in this large series suggests that the risk of an episode in these patients is extremely low and may be negligible. We suggest that anaesthetic triggering agents can be used safely in patients with normal in vitro contracture tests, and in their descendants.

Safe duration of postoperative monitoring for malignant hyperthermia patients administered non-triggering anaesthesia: an update.

The postoperative care of malignant hyperthermia (MH) patients is subject to international variation, with a paucity of data in the literature to guide management. Over a series of three studies, our aim was to evaluate whether MH-susceptible patients (and relatives who had not yet been investigated), who had received a non-triggering anaesthetic, could be managed in the same way as the standard surgical population. Following a retrospective study, 206 anaesthetics were administered in a prospective second study to MH-susceptible/related individuals who were monitored for a minimum of one hour in the post anaesthesia care unit and a further 90 minutes in a step-down facility. No problems relating to MH were encountered. The postoperative monitoring time was subsequently changed and, in a third study, patients were managed no differently from standard surgical patients. One hundred and twenty-five anaesthetics were administered with no evidence of problems. This data shows that standard postoperative monitoring times are safe and appropriate in MH-susceptible patients.

Preparation of Datex-Ohmeda Aestiva and Aisys anaesthetic machines for use in malignant hyperthermia susceptible patients.

Preparation of anaesthesia machines for use by malignant hyperthermia susceptible patients requires purging the machines of halogenated anaesthetic agents. The endpoint of this process is to reach a gas concentration of 5 ppm or less, which has been arbitrarily chosen as the safe limit of exposure to avoid triggering a malignant hyperthermia event. We examined the washout characteristics of sevoflurane and desflurane from the Datex-Ohmeda Aestiva Anaesthesia System and Aisys Anaesthesia Carestation anaesthetic machines. The machines were contaminated for two hours using either sevoflurane 2 vol% or desflurane 6 vol%. At the end of the priming period, the patient breathing circuit and reservoir bag, carbon dioxide absorbent, sampling line and test lung were replaced with uncontaminated components. During the test period, machines were purged using oxygen flows of 10 l/minute. The average time to reach 5 ppm with the Aestiva machines was 51 minutes with sevoflurane and 71 minutes with desflurane. The average time to reach 5 ppm for the Aisys machines was 55 minutes with sevoflurane and 69 minutes with desflurane. All configurations of machines and anaesthetic gases demonstrated a rebound effect in agent concentration above 5 ppm when the fresh gas flow was subsequently reduced from 10 to 2 l/minute. Aestiva and Aisys anaesthetic machines require a prolonged period to adequately purge them of halogenated volatile anaesthetic agent. The rebound effect poses a serious concern, suggesting that after the purging period, fresh gas flows of 10 l/minute should be maintained for the duration of anaesthesia care of the malignant hyperthermia susceptible patient.

Safety of exposure of malignant hyperthermia non-susceptible patients and their relatives to anaesthetic triggering agents.

As the reliability of malignant hyperthermia normal in vitro contracture test results has been questioned, this study set out to determine the reliability of malignant hyperthermia normal results in New Zealand. Three hundred and twenty-nine anaesthetics were administered to malignant hyperthermia normal patients, identified through the Palmerston North Hospital malignant hyperthermia database. Anaesthetic records were retrieved and scrutinised for a malignant hyperthermia reaction using the Malignant Hyperthermia Clinical Grading Scale. Patients were exposed to one or more of eight triggering agents and multiple anaesthetic agents were administered in 41% of cases. Six variables were analysed, and although a minority of variables were abnormal in a small number of patients, none of the findings supported a malignant hyperthermia reaction. While the analysis was limited by the adequacy of the anaesthesia records, it was supported by negative DNA analysis in 55% of patients. This study supports several previous studies in demonstrating that patients in New Zealand tested non-susceptible to malignant hyperthermia can safely be given triggering agents.

Client acceptability and quality of life--telepsychiatry compared to in-person consultation.

We evaluated client satisfaction and one-month mental health outcomes for telepsychiatry clients compared with those undergoing a face-to-face psychiatric consultation. Clients were asked to complete an SF-12 health survey before the consultation, a satisfaction survey after the consultation, and were contacted for a one-month follow-up SF-12 survey by telephone. Forty-eight of the 62 initial responders (77%) were available for contact by telephone after one month. Telepsychiatry clients demonstrated significant improvements on pre- and post-SF-12 mental health measures (t = 3.7; P = 0.001), while there was no change for the in-person group (t = 1.0; P = 0.35). Telepsychiatry clients felt that they could present the same information as in person (93%), were satisfied with their session (96%), and were comfortable in their ability to talk (85%); this was similar to the in-person clients. They reflected slightly lower levels of satisfaction regarding feeling supported and encouraged than did the in-person clients. Both telepsychiatry clients and traditional face-to-face psychiatry clients were satisfied with their experience of mental health care service provision, and mental health improvements were evident in the telepsychiatry patients.

A cut above: the rising Caesarean section rate in New Zealand.

AIM: To examine the trends in frequency of Caesarean section in New Zealand. METHODS: Caesarean section rates (CSR) were calculated from the National Minimum Data Set between 1988/89 and 1994/95. Demographic data relating to women having Caesarean sections were examined for 1994/95. The results were checked with regional health authorities and Crown health enterprises containing teaching hospitals. RESULTS: The national CSR, which was 9.6% in 1983/84, increased from 11.6% in 1988/89 to 15.3% in 1994/95. Previous Caesarean and dystocia are reported to be the indicators for nearly half of all Caesareans. CONCLUSIONS: The national CSR is high and continues to increase. The international literature shows that national recommendations to reduce the CSR are less effective than hospital-based initiatives.