Portable HEPA filtration successfully augments natural-ventilation-mediated airborne particle clearance in a legacy design hospital ward.

As the severe acute respiratory syndrome coronavirus-2 pandemic has proceeded, ventilation has been recognized increasingly as an important tool in infection control. Many hospitals in Ireland and the UK do not have mechanical ventilation and depend on natural ventilation. The effectiveness of natural ventilation varies with atmospheric conditions and building design. In a challenge test of a legacy design ward, this study showed that portable air filtration significantly increased the clearance of pollutant aerosols of respirable size compared with natural ventilation, and reduced spatial variation in particle persistence. A combination of natural ventilation and portable air filtration is significantly more effective for particle clearance than either intervention alone.

Containment of procedure-associated aerosols by an extractor tent: effect on nebulized drug particle dispersal.

BACKGROUND: Several medical procedures involving the respiratory tract are considered as 'aerosol-generating procedures'. Aerosols from these procedures may be inhaled by bystanders, and there are consequent concerns regarding the transmission of infection or, specific to nebulized therapy, secondary drug exposure. AIM: To assess the efficacy of a proprietary high-efficiency-particulate-air-filtering extractor tent on reducing the aerosol dispersal of nebulized bronchodilator drugs. METHODS: The study was conducted in an unoccupied outpatient room at St. James's Hospital, Dublin, Ireland. A novel real-time, fluorescent particle counter, the Wideband Integrated Bioaerosol Sensor (WIBS), monitored room air continuously for 3 h. Baseline airborne particle count and count during nebulization of bronchodilator drug solutions were recorded. FINDINGS: Nebulization within the tent prevented any increase over background level. Nebulization directly into room air resulted in mean fluorescent particle counts of 4.75 x 105/m3 and 4.21 x 105/m3 for Ventolin and Ipramol, respectively, representing more than 400-fold increases over mean background level. More than 99.3% of drug particles were <2 µm in diameter and therefore small enough to enter the lower respiratory tract. CONCLUSION: The extractor tent was completely effective for the prevention of airborne spread of drug particles of respirable size from nebulized therapy. This suggests that extractor tents of this type would be efficacious for the prevention of airborne infection from aerosol-generating procedures during the COVID-19 pandemic.

Effectiveness of a plasma treatment device on microbial air quality in a hospital ward, monitored by culture.

This study analysed the effectiveness of plasma treatment on airborne bacteria and surface counts during a 14-day intervention within a four-bedded bay in an adult respiratory ward at Cork University Hospital, Ireland. One-hundred-litre air samples were collected twice daily every weekday for 4 weeks, with settle plates and surface swabs. The plasma treatment did not have an effect on airborne bacteria and fungi that was detectable by culture. However, the possibility that culture-based sampling may be insufficiently sensitive to detect an effect, or that the duration of the study was insufficient for plasma treatment to affect a complex environment, cannot be excluded.

Anaphylaxis secondary to levobupivacaine.

We describe the case of a 25-year-old woman presented for elective lumbar decompression and microdiscectomy who, towards the end of her surgery, developed clinical signs of anaphylaxis. Skin testing later confirmed sensitisation to levobupivacaine and possibly MediShield, an anti-adhesion gel used following microdiscectomy. This case is the first confirmed case report of anaphylaxis in response to levobupivacaine. It also highlights the possibility that multiple agents may simultaneously trigger a life-threatening reaction. Anaesthetists should remain alert to the use of potentially allergenic agents employed by surgeons.

The efficacy of surgically placed epidural catheters for analgesia after posterior spinal surgery.

Posterior spinal fusion for correction of scoliosis is a major procedure for which the provision of satisfactory, safe postoperative analgesia is often a problem. One possible solution involves the placement of epidural catheters under direct vision by the surgeon at the end of the procedure, followed by an epidural infusion of local anaesthetic with or without an opioid. Despite its simplicity, this technique has not been reported as being consistently successful. We report an observational study of the analgesia achieved with surgically placed epidural catheters and of the reasons for the failure of the technique. Fourteen consecutive patients undergoing posterior spinal fusion had epidural catheters placed by the surgeon and had radio-opaque dye injected down the catheter 15 min before their routine postoperative chest X-ray. Analgesia was assessed at 0, 6, 12 and 24 h after surgery using visual analogue scores. Five patients had inadequate pain control; none of these patients had dye visible in the epidural space. Seven patients had dye visible in the epidural space; all of these cases had satisfactory analgesia. In two cases, dye was observed in the paravertebral gutters; both of these patients had satisfactory postoperative analgesia. This small pilot study suggests that correctly placed 'surgical' epidural catheters are capable of providing good analgesia after posterior spinal fusion and that misplaced catheters, seen in a large proportion of patients, are associated with inadequate analgesia.

Comparison of ondansetron, metoclopramide and placebo as premedicants to reduce nausea and vomiting after major surgery.

In a randomised, double-blind study, we have compared the incidence of postoperative nausea and vomitting in 124 patients undergoing major lower limb orthopaedic surgery following oral premedication with temazapam and ondansetron 8 mg, metoclopramide 10 mg or placebo. They received a standardised epidural and general anaesthetic. An epidural mixture containing bupivacaine 0.1% and fentanyl 10 mg.ml-1 was infused postoperatively. The occurrence of nausea and vomiting was assessed every 4 h for 24 h. The incidence of vomiting significantly decreased from 55% and 43% in the placebo and metoclopramide groups, respectively, to 26% in the ondansetron group (p = 0.03). The incidence of nausea and vomiting in patients who had previously suffered was also significantly reduced from 67% and 68% in the placebo and metoclopramide groups, respectively, to 29% in the ondansetron group (p = 0.035). We conclude that oral premedication with ondansetron 8 mg was superior to metoclopramide 10 mg and placebo in preventing postoperative nausea and vomiting following major orthopaedic surgery in patients given epidural opioid analgesia.

An unusual manifestation of bleeding diathesis in a patient with osteogenesis imperfecta.

We present the anaesthetic and surgical management, and post-operative course of a patient with osteogenesis imperfecta which exemplifies the problems associated with this condition. The observed petechial haemorrhagic rash is not characteristic of the bleeding tendency in osteogenesis imperfecta nor characteristic of acute disseminated intravascular coagulation. Despite potential life-threatening complications the patient made a good recovery and was discharged 3 weeks after surgery.

The effects of differing concentrations of bupivacaine on the epidural somatosensory evoked potential after posterior tibial nerve stimulation.

The somatosensory evoked potential (SEP) recorded from the cervical epidural space in response to stimulation of the posterior tibial nerve is often used to monitor spinal cord integrity during scoliosis surgery. Epidural analgesia may be used as part of the anesthetic technique for scoliosis surgery, but the effects of the local analgesic on the evoked potential must be determined to ensure that it does not interfere with the monitoring of spinal cord function. Therefore, we compared the effects of the administration of 10 mL of 0.25% (n = 8), 0.5% (n = 8), or 0.75% (n = 8) bupivacaine injected into the L3-4 epidural space on the somatosensory evoked potential to posterior tibial nerve stimulation in patients anesthetized with a propofol infusion, nitrous oxide and oxygen, immediately before scoliosis surgery. Compared with a control group (n = 8), a concentration-dependent effect of bupivacaine was found on overall amplitude of the evoked potentials and the amplitude of all peaks. There were no significant differences between 0.25% bupivacaine and the control group, but both 0.5% and 0.75% bupivacaine were associated with clinically and statistically significant decreases in overall amplitude (P < 0.002, 0.5% bupivacaine; P < 0.001, 0.75% bupivacaine). Latency increased similarly in all groups. We conclude that bupivacaine in concentrations greater than 0.25% is not suitable for scoliosis surgery, if spinal somatosensory evoked potentials (SSEP) are to be measured.

Comparison of different methods of administering droperidol in patient-controlled analgesia in the prevention of postoperative nausea and vomiting.

We performed a double-blind, placebo-controlled study to evaluate the different methods of administering droperidol in patients using patient-controlled analgesia (PCA) with morphine. Eighty patients undergoing major orthopedic procedures received temazepam 0.2 mg/kg orally followed by induction of general anesthesia with propofol 2.5 mg/kg, fentanyl 2 micrograms/kg, and vecuronium 0.1 mg/kg. Anesthesia was maintained with nitrous oxide, oxygen, and enflurane. At the end of surgery, all patients received PCA with morphine (0.5 mg/mL, bolus dose 1 mg, and lockout interval 5 min. Before commencement of PCA, patients were randomized to receive droperidol 1.25 mg immediately and, in addition, droperidol 0.16 mg with each PCA dose (Group 1), droperidol 1.25 mg immediately (Group 2), droperidol 0.16 mg with each PCA dose (Group 3), and no droperidol (Group 4). Incidence of nausea and vomiting, request for rescue antiemetics, sedation score, and side effects were recorded every 4 h. Droperidol significantly reduced the incidence of postoperative nausea and vomiting (PONV) (P < 0.01) and request for rescue antiemetic (P < 0.01) compared to placebo. However, there was no difference in the incidence of PONV between droperidol given either as a single dose at the end of surgery (Group 2) or mixed in morphine PCA (Group 3). The addition of droperidol in PCA after an initial dose (Group 1) should be avoided, as it resulted in more sedation and no further reduction in the incidence of PONV compared to Groups 2 and 3.

Temporal summation--the key to motor evoked potential spinal cord monitoring in humans.

Spinal motor evoked potentials (SMEP) were recorded from tibialis anterior muscle after epidural stimulation of the spinal cord at the low cervical or high thoracic level during scoliosis surgery. By using a double stimulus pulse to produce temporal summation within the spinal cord a maximal CMAP response was readily achieved despite good surgical anaesthesia.

Midazolam sedation reversed with flumazenil for cardioversion.

Midazolam was used for anaesthesia in 20 patients undergoing cardioversion; 10 received flumazenil, which caused immediate rapid reversal of anaesthesia, and these patients maintained SpO2 greater than 95%, breathing air, within 5-10 min. In contrast, patients in the placebo group were still partially sedated and required oxygen therapy for up to 2 h to maintain a normal SpO2. Arterial pressure, but not heart rate, also was greater in the flumazenil group in the recovery period.

Is caffeine withdrawal the mechanism of postoperative headache?

This study examined the hypothesis that headache after general anesthesia is related to a caffeine withdrawal state. Two hundred eighty-seven patients undergoing minor elective procedures under general anesthesia were studied. Four to six hours after anesthesia each patient completed a questionnaire assessing his or her own alcohol, tobacco, and caffeine consumption, and the occurrence of postoperative side effects. A highly significant difference was found between the caffeine consumption of patients with and without preoperative (P = 0.0035) and postoperative (P less than 0.0001) headache. Logistic regression analysis of trend between headache and caffeine consumption suggested that with each 100-mg increase in caffeine consumption, there was a 12% increase in the odds of headache developing in the immediate preoperative period (P less than 0.0066) and a 16% increase in the odds of postoperative headache developing (P less than 0.0001). No relationship was found between headache and the patients' age, sex, usual frequency of headache, consumption of alcohol or nicotine, or the anesthetic agents or adjuvants used. It is concluded that postoperative headache is related to caffeine intake and that this relationship is explained, at least in part, by a perioperative caffeine withdrawal syndrome.

Blood loss reduced during hip arthroplasty by lumbar plexus block.

We measured the blood loss during and after hip replacement in two groups of women, each consisting of 10 patients. In one group the lumbar plexus was infiltrated with bupivacaine, in the other it was not. The group in whom the plexus was blocked had significantly less blood loss.