Nolan Mcdonnell

Difficult and failed intubation in obstetric anaesthesia: an observational study of airway management and complications associated with general anaesthesia for caesarean section

BACKGROUND Recent developments in anaesthesia and patient demographics have potentially changed the practice of obstetric general anaesthesia. There are few contemporary data on Australasian practice of general anaesthesia for caesarean section, especially relating to airway management, anaesthetic techniques and complications. METHODS Using a standardised case record form, a prospective observational study was conducted during 2005-06 in 13 maternity hospitals dealing with approximately 49 500 deliveries per annum. Patient demographics, airway management, anaesthetic techniques and major complications were evaluated in those given general anaesthesia. RESULTS Data were obtained from 1095 women receiving general anaesthesia for caesarean section, 47% of which were classified as category 1 and 18% as category 4. Tracheal intubation was planned in all cases with rapid-sequence induction used in 97%. A grade 3 or 4 laryngoscopic view was obtained in 3.6 and 0.6% of cases respectively, with 3.3% considered a difficult intubation. There were four failed intubations (0.4%, 95% CI 0.01-0.9%), of which three were subsequently managed using a laryngeal mask airway. Antacid prophylaxis was used in 94% of elective cases and 64% of emergencies. Regurgitation of gastric contents was noted in eight cases (0.7%, 95% CI 0.2-1.2%), with one confirmed case of aspiration (0.1%, 95% CI 0.002-0.5%). There were no cases of serious airway-related morbidity. CONCLUSIONS General anaesthesia is most commonly used in emergency situations. Tracheal intubation after rapid-sequence induction remains the predominant approach to airway management in Australasia. The incidence of failed intubation is consistent with previous studies. Aspiration prophylaxis is not routinely used for emergency surgery.

A Prospective study of awareness and recall associated with general anaesthesia for caesarean section

BACKGROUND The obstetric population is considered at high risk of awareness and recall when undergoing general anaesthesia for caesarean section. In recent years the incidence may have been altered by developments in obstetric anaesthesia. METHODS A prospective observational study of general anaesthesia for caesarean section was conducted during 2005 and 2006 in 13 maternity hospitals dealing with approximately 49,500 deliveries per annum in Australia and New Zealand. As a component of this study the frequency of recall of intraoperative events was examined using a structured postoperative interview on two occasions. RESULTS There were 1095 general anaesthetics surveyed with 47% being performed for urgent fetal delivery. Thiopental was the most common induction agent (83%) with sevoflurane being used for maintenance in 63%. In 32% of cases a depth-of-anaesthesia monitor was used. In 763 cases (70%) there was least one postoperative interview enquiring into dreaming and awareness. There were two cases deemed to be consistent with awareness (incidence 0.26%, CI 0.03-0.9%, or 1 in 382) and three cases of possible awareness. CONCLUSION Awareness with recall of intraoperative events remains a significant complication of obstetric general anaesthesia but was potentially avoidable in all cases detected in this study.

Recommendations for the diagnosis and treatment of deep venous thrombosis and pulmonary embolism in pregnancy and the postpartum period

Venous thromboembolism (VTE) in pregnancy and the postpartum is an important cause of maternal morbidity and mortality; yet, there are few robust data from clinical trials to inform an approach to diagnosis and management. Failure to investigate symptoms suggestive of pulmonary embolism (PE) is a consistent finding in maternal death enquiries, and clinical symptoms should not be relied on to exclude or diagnose VTE. In this consensus statement, we present our recommendations for the diagnosis and management of acute deep venous thrombosis (DVT) and PE. All women with suspected DVT in pregnancy should be investigated with whole leg compression ultrasonography. If the scan is negative and significant clinical suspicion remains, then further imaging for iliofemoral DVT maybe required. Imaging should be undertaken in all women with suspected PE, as the fetal radiation exposure with both ventilation/perfusion scans and CT pulmonary angiography is within safe limits. Low‐molecular‐weight heparin (LMWH) is the preferred therapy for acute VTE that occur during pregnancy. In observational cohort studies, using once‐daily regimens appears adequate, in particular with the LMWH tinzaparin; however, pharmacokinetic data support twice‐daily therapy with other LMWH and is recommended, at least initially, for PE or iliofemoral DVT in pregnancy. Treatment should continue for a minimum duration of six months, and until at least six weeks postpartum. Induction of labour or planned caesarean section maybe required to allow an appropriate transition to unfractionated heparin to avoid delivery in women in therapeutic doses of anticoagulation.

Recommendations for the prevention of pregnancy-associated venous thromboembolism.

Pregnancy is a risk factor for venous thromboembolism (VTE), an important cause of maternal morbidity and mortality. Although there is a 4–5‐fold increased risk compared to that of nonpregnant women of the same age, the absolute risk is low at no more than two episodes of VTE per 1000 pregnancies. There is uncertainty about which women require thromboprophylaxis during pregnancy or postpartum because of a lack of data from appropriate clinical trials. For this reason, recommendations for prophylaxis should be made only after explaining the available evidence to the patient and taking into account her perception of the balance of risk and benefit in thromboprophylaxis. The aim of these recommendations is to provide clinicians with practical advice to assist in decisions regarding thromboprophylaxis in women considered to be at risk of VTE during pregnancy and the postpartum. The authors are clinicians from across New Zealand and Australia representing the fields of haematology, obstetric medicine, anaesthesiology, maternal–fetal medicine and obstetrics. Authors were invited to review the relevant literature and then worked collaboratively to devise recommendations and resolve areas of controversy. The recommendations contained herein were reached by consensus and represent the opinion of the panel. The absence of randomised clinical trials in this area limits the strength of evidence that can be used, and it is acknowledged that they represent level C evidence. The panel advocates for appropriate clinical studies to be carried out in this patient population to address the inadequacy of present evidence.

Acute magnesium toxicity in an obstetric patient undergoing general anaesthesia for caesarean delivery

Magnesium is commonly used in the prevention of eclampsia. Reports of acute toxicity are rare and we are not aware of detailed management algorithms. We present a case of acute magnesium toxicity presenting as ventilatory impairment and failure to rouse adequately from general anaesthesia. The patient was managed with controlled ventilation, further sedation, intravenous calcium gluconate, forced diuresis and dextrose-insulin infusion. We present a guideline for the management of life-threatening magnesium toxicity and discuss measures that may prevent future similar occurrences.

Maternal mortality in Australia: Learning from maternal cardiac arrest

Cardiac arrest in pregnancy is fortunately a rare event that few midwives will see during their career. The increase in maternal age, the Body Mass Index, cesarean sections, multiple pregnancies, and comorbidities over recent years have increased the probability of cardiac arrest. The early warning signs of impending maternal cardiac arrest are either absent or go unrecognized. Maternal mortality reviews highlight the deficiencies that maternity care providers have in managing cardiac arrest in pregnancy.The aim of this article is to address the knowledge deficiencies of health professionals by reviewing the physiological changes in pregnant women that complicate the management of cardiopulmonary resuscitation, using a case scenario. There are key differences in the management of pregnant women, when compared to standard adult resuscitation.The outcome is dependent on the speed of the response and the consideration of a number of crucial pregnancy-specific interventions. Staff members need to be adequately trained in order to deal with maternal cardiac arrest and have access to training packages and in-service education programs. As cardiac arrest in pregnancy is a rare event, emergency drill simulations are an important component of ongoing education.Cardiac arrest in pregnancy is fortunately a rare event that few midwives will see during their career. The increase in maternal age, the Body Mass Index, cesarean sections, multiple pregnancies, and comorbidities over recent years have increased the probability of cardiac arrest. The early warning signs of impending maternal cardiac arrest are either absent or go unrecognized. Maternal mortality reviews highlight the deficiencies that maternity care providers have in managing cardiac arrest in pregnancy. The aim of this article is to address the knowledge deficiencies of health professionals by reviewing the physiological changes in pregnant women that complicate the management of cardiopulmonary resuscitation, using a case scenario. There are key differences in the management of pregnant women, when compared to standard adult resuscitation. The outcome is dependent on the speed of the response and the consideration of a number of crucial pregnancy-specific interventions. Staff members need to be adequately trained in order to deal with maternal cardiac arrest and have access to training packages and in-service education programs. As cardiac arrest in pregnancy is a rare event, emergency drill simulations are an important component of ongoing education.

A Clinical Evaluation of the GemStar® and the AmbIT® Pumps for Patient-Controlled Epidural Analgesia.

Background Patient-controlled analgesia is used for both labor and postoperative analgesia. Objectives This study aimed to assess user satisfaction and functionality of two ambulatory, electronic patient controlled analgesia devices, the GemStar pump Hospira Inc., Illinois, USA) and the ambIT Ambulatory Infusion Therapy pump (Sorenson Medical Products, Utah, USA). Patients and Methods It was a randomized clinical trial of laboring women and postoperative gynecology patients receiving patient-controlled epidural analgesia. Patients were randomized to use one of the pumps and both anesthesiologists and patients completed questionnaires about aspects of pump function, and rated their satisfaction with the equipment. Midwives and high-dependency unit nurses also evaluated the pumps in each clinical setting. Results Forty patients, 20 laboring women and 20 postoperative patients were randomized and completed the study. The pumps were compared by nine anesthesiologists. Patient and staff satisfaction with both devices was high. Patient satisfaction did not significantly differ between groups (median 10 [8, 10] for the GemStar and 10 [9, 10] for the ambIT, P = 0.525]. The median staff satisfaction score was 8 [6, 8] for the GemStar and 7 [5, 8] for the ambIT (P = 0.154). Both patient cohorts rated each pump highly for most aspects of clinical function. Staff rated the ambIT pump more favourably with respect to portability and storage at the bedside whilst the GemStar had better assessments with respect to its consumables and interactions involving the electronic interface. Conclusions Both devices were well-rated by patients and staff, with no significant difference between them for overall satisfaction, and only minor differences with respect to their respective strengths and weaknesses.

A randomised double-blind trial of phenylephrine and metaraminol infusions for prevention of hypotension during spinal and combined spinal–epidural anaesthesia for elective caesarean section

Prophylactic vasopressor administration is commonly recommended to reduce maternal hypotension during spinal anaesthesia for caesarean section. Metaraminol has undergone limited investigation in obstetric anaesthesia for this purpose, particularly in comparison with phenylephrine. In this multicentre, randomised, double‐blind, non‐inferiority study, we compared prophylactic phenylephrine or metaraminol infusions, started immediately after spinal anaesthesia, in 185 women who underwent elective caesarean section. Phenylephrine was initially infused at 50 μg.min−1, and metaraminol at 250 μg.min−1. The primary outcome was the difference in umbilical arterial pH between groups; secondary outcomes included other neonatal acid‐base measures, and maternal haemodynamic changes. The mean (SD) umbilical arterial pH was 7.28 (0.06) in the phenylephrine group vs. 7.31 (0.04) in the metaraminol group (p = 0.0002). The estimated mean (95%CI) pH difference of 0.03 (0.01–0.04) was above the pre‐determined lower boundary of clinical non‐inferiority, and also met the criterion for superiority. Umbilical artery lactate concentration was 2.8 (1.2) mmol.l−1 in the phenylephrine group vs. 2.3 (0.7) mmol.l−1 in the metaraminol group (p = 0.0018). Apgar scores did not significantly differ between groups. There was a higher incidence of hypotension, defined as systolic arterial pressure < 90% baseline, in the phenylephrine group; there was a higher incidence of hypertension and severe hypertension (systolic arterial pressure > 110% and > 120% baseline, respectively) in the metaraminol group. There was no significant difference between groups in the incidence of nausea, vomiting or maternal bradycardia. We conclude that, when used as an infusion to prevent hypotension after spinal anaesthesia for elective caesarean section, metaraminol is at least non‐inferior to phenylephrine with respect to neonatal acid‐base outcomes.

Sugammadex and anaphylaxis in the operating theater

a Retired. Formerly, Head, Molecular Immunology Unit, Kolling Institute of Medical Research, Royal North Shore Hospital of Sydney and Department of Medicine, University of Sydney, Sydney, NSW, Australia b Department of Anaesthesia and Pain Medicine, King Edward Memorial Hospital for Women and School of Women’s and Infants’ Health and School of Medicine and Pharmacology, University of Western Australia, Perth, WA, Australia

Immediate postpartum neurological deficits in the lower extremity: a prospective observational study

BACKGROUND Neurological deficits noted immediately after childbirth are usually various obstetric neuropathies, but prospective studies are limited. The main study aim was to quantify and describe immediate postpartum neurological deficits of the lower extremity, including the buttocks. METHODS A prospective observational study of postpartum women delivering in a single maternity hospital during three months of 2016. Among 1147 eligible women, 1019 were screened for symptoms of lower extremity numbness or weakness within eight to 32hours of delivery. Consent to undergo a detailed neurological evaluation was sought from those reporting symptoms. Risk factors were identified using logistic regression. RESULTS Thirty five women (3.4%) reported symptoms, 27 entered the study and 23 (2.0%) had objective signs of a neurological deficit. The most common injuries were mild lumbosacral plexopathies and cluneal nerve compression. Most deficits were sensory, half of these also having a motor deficit that did not impact functionally. Based on analysis of 22 cases involving a likely intrapartum deficit, no association was found with parity, body weight, duration of labour, mode of delivery or neuraxial block. A past history of a neurological condition or a back injury was associated with odds ratios of 7.98 and 4.82 respectively. There were no neurological deficits that were clinically concerning or that were likely a complication of a neuraxial block. CONCLUSION Transient neurological complications after labour and delivery are infrequent, mainly sensory involving multiple lumbosacral nerve roots or specific sacral cutaneous nerves, and they typically resolve within a short time.