Effective prevention of post-dural puncture headache with insertion of an intrathecal catheter in parturients: a retrospective study and meta-analysis

BACKGROUND

Accidental dural puncture is a common complication of labour analgesia. It can trigger post-dural puncture headache, with associated morbidity and increased costs. Intrathecal catheter placement is a prophylactic procedure which can reduce incidence and severity of post-dural puncture headache.

METHODS

We conducted a retrospective single-centred study to define incidence and risk factors of accidental dural puncture and post-dural puncture headache in an obstetric population. We also evaluated effectiveness of intrathecal catheter placement compared to epidural catheter replacement in reducing incidence of post-dural puncture headache. We then conducted a systematic review and meta-analysis which included all studies comparing intrathecal catheter placement to epidural catheter replacement in obstetric patients with accidental dural puncture assessing the outcome of reduced incidence of post-dural puncture headache as a dichotomous variable.

RESULTS

Accidental dural puncture had an incidence of 0.25% (60 cases). Of these, 66% developed post-dural puncture headache. A total of 77% (47/60) of patients with accidental dural puncture were treated with an intrathecal catheter placement, while 23% (13/60) had an epidural catheter replacement. Incidence of post-dural puncture headache was lower in the intrathecal catheter group (spinal 26/47, 60.5% epidural 11/13, 84.6%), although not reaching statistical significance (RR 0.71, CI 95%: 0.51-1.00; p = 0.049). The meta-analysis revealed that intrathecal catheter placement significantly reduced incidence of post-dural puncture headache compared to epidural catheter replacement (pooled RR 0.81, 95% CI 0.72-0.91, p < 0.001).

CONCLUSIONS

Intrathecal catheter placement is a promising measure to prevent post-dural puncture headache, especially if followed by a pain management protocol and a continuous saline infusion.

Lung volumes, respiratory mechanics and dynamic strain during general anaesthesia

BACKGROUND

Driving pressure (ΔP) represents tidal volume normalised to respiratory system compliance (C_RS) and is a novel parameter to target ventilator settings. We conducted a study to determine whether C_RS and ΔP reflect aerated lung volume and dynamic strain during general anaesthesia.

METHODS

Twenty non-obese patients undergoing open abdominal surgery received three PEEP levels (2, 7, or 12 cm H₂O) in random order with constant tidal volume ventilation. Respiratory mechanics, lung volumes, and alveolar recruitment were measured to assess end-expiratory aerated volume, which was compared with the patient's individual predicted functional residual capacity in supine position (FRCp).

RESULTS

C_RS was linearly related to aerated volume and ΔP to dynamic strain at PEEP of 2 cm H₂O (intraoperative FRC) (r=0.72 and r=0.73, both P<0.001). These relationships were maintained with higher PEEP only when aerated volume did not overcome FRCp (r=0.73, P<0.001; r=0.54, P=0.004), with 100 ml lung volume increases accompanied by 1.8 ml cm H₂O^-1 (95% confidence interval [1.1-2.5]) increases in C_RS. When aerated volume was greater or equal to FRCp (35% of patients at PEEP 2 cm H₂O, 55% at PEEP 7 cm H₂O, and 75% at PEEP 12 cm H₂O), C_RS and ΔP were independent from aerated volume and dynamic strain, with C_RS weakly but significantly inversely related to alveolar dead space fraction (r=-0.47, P=0.001). PEEP-induced alveolar recruitment yielded higher C_RS and reduced ΔP only at aerated volumes below FRCp (P=0.015 and 0.008, respectively).

CONCLUSIONS

During general anaesthesia, respiratory system compliance and driving pressure reflect aerated lung volume and dynamic strain, respectively, only if aerated volume does not exceed functional residual capacity in supine position, which is a frequent event when PEEP is used in this setting.

New experimental Oximes in the management of organophosphorus pesticides poisoning

Organophosphorus compounds (OPCs) are widely used in agriculture as pesticides and occasionally in industrial settings. They have also been developed as warfare nerve agents. OPCs poisoning from intentional, accidental, and occupational exposure is a major public health problem, especially across the rural developing world. The main toxic mechanism of OPCs is the inhibition of the enzymes acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE), resulting in accumulation of acetylcholine (ACh) at the synapse with cholinergic crisis and possible death. Exposure to even small amounts of an OPC can be fatal and death is usually caused by respiratory failure. Standard treatment involves the administration of intravenous atropine and an oxime to counteract acetylcholinesterase inhibition at the synapse, but the usefulness of oximes is still debated. During more than five decades, pyridinium oximes have been developed as therapeutic agents used in the medical treatment of poisoning with OPCs. They act by reactivation of AChE inhibited by OPCs. However, their activity in poisonings with pesticides and warfare nerve agents is different, and there is still no universal oxime sufficiently effective against all known OPCs. The aim of this article was to review the most recent findings in this field and compare the protection conferred by the new K-oximes and sugar oximes with the effect of the four recommended pyridinium oximes (pralidoxime, obidoxime, trimedoxime, and HI-6), in the search for a broad-spectrum AChE reactivator.