Hyperventilation during cardiopulmonary resuscitation (CPR) negatively affects cardiopulmonary physiology. Compression-adjusted ventilations (CAVs) may allow providers to deliver ventilation rates more consistently than conventional ventilations (CVs). This study sought to compare ventilation rates between these two methods during simulated cardiac arrest.

That CAV will not result in different rates than CV in simulated CPR with metronome-guided compressions.

Volunteer Basic Life Support (BLS)-trained providers delivered bag-valve-mask (BVM) ventilations during simulated CPR with metronome-guided compressions at 100 beats/minute. For the first 4-minute interval, volunteers delivered CV. Volunteers were then instructed on how to perform CAV by delivering one breath, counting 12 compressions, and then delivering a subsequent breath. They then performed CAV for the second 4-minute interval. Ventilation rates were manually recorded. Minute-by-minute ventilation rates were compared between the techniques.

A total of 23 volunteers were enrolled with a median age of 36 years old and with a median of 14 years of experience. Median ventilation rates were consistently higher in the CV group versus the CAV group across all 1-minute segments: 13 vs 9, 12 vs 8, 12 vs 8, and 12 vs 8 for minutes one through four, respectively (P <.01, all). Hyperventilation (>10 breaths per minute) occurred 64% of the time intervals with CV versus one percent with CAV (P <.01). The proportion of time which hyperventilation occurred was also consistently higher in the CV group versus the CAV group across all 1-minute segments: 78% vs 4%, 61% vs 0%, 57% vs 0%, and 61% vs 0% for minutes one through four, respectively (P <.01, all).

In this simulated model of cardiac arrest, CAV had more accurate ventilation rates and fewer episodes of hyperventilation compared with CV.

Nikolla DA, Kramer BJ, Carlson JN. A cross-over trial comparing conventional to compression-adjusted ventilations with metronome-guided compressions. Prehosp Disaster Med. 2019;34(2):220–223

The objective of this review is to investigate existing literature in order to delineate whether the use of anaesthesia and timing of seizure induction in a new and optimised way may improve the efficacy of electroconvulsive therapy (ECT).

PubMed/MEDLINE was searched for existing literature, last search on 24 June 2015. Relevant clinical studies on human subjects involving choice of anaesthetic, ventilation and bispectral index (BIS) monitoring in the ECT setting were considered. The references of relevant studies were likewise considered.

Propofol yields the shortest seizures, etomidate and ketamine the longest. Etomidate and ketamine+propofol 1 : 1 seems to yield the seizures with best quality. Seizure quality is improved when induction of ECT is delayed until the effect of the anaesthetic has waned – possibly monitored with BIS values. Manual hyperventilation with 100% O2 may increase the pO2/pCO2-ratio, which may be correlated with better seizure quality.

Etomidate or a 1 : 1 ketamine and propofol combination may be the best method to achieve general anaesthesia in the ECT setting. There is a need for large randomised prospective studies comparing the effect of methohexital, thiopental, propofol, ketamine, propofol+ketamine 1 : 1 and etomidate in the ECT treatment of major depressed patients. These studies should investigate safety and side effects, and most importantly have antidepressant efficacy and cognitive side effects as outcome measures instead of seizure quality.

To observe spike activity in electroencephalograms (EEGs), patients with symptomatic partial epilepsy are rarely monitored during the hyperventilation stages.

A 38-year-old woman suffered from a ruptured arteriovenous malformation in the left temporal lobe. One and a half years later, the patient experienced her first generalized convulsion. EEG showed small spikes in the posterior of the left temporal lobe, which was observed during the hyperventilation and posthyperventilation stages. Because the location of the spikes correlated with the site of the lesion as observed from radiographic findings, she was diagnosed with lateral temporal lobe epilepsy. Drug treatment resulted in no further convulsive episodes and the patient has since returned to work.

EEG recordings during hyperventilation should be regarded as an effective technique in analyzing epilepsy because of its ease and cost-effectiveness compared with other methods such as single-photon emission computed tomography.

The Brain Trauma Foundation's Guidelines for the Management of Severe Head Injury state that the use of prophylactic hyperventilation after traumatic brain injury (TBI) should be avoided because it can compromise cerebral perfusion. The objective of this study was to assess the prevalence of unintentional hyperventilation.

A prospective evaluation of all intubated trauma patients with a diagnosis of TBI was performed. Patients with signs of impending hernia-tion were excluded.

Forty patients were included in the study. The average Glasgow Coma Scale (GCS) was 6.3. Of these, 28 patients (70%) were unintentionally hyperventilated. Eleven (39%) of the hyperventilated patients died or were discharged in a persistent vegetative state. Of the remaining 12 patients who experienced normal ventilation, three patients (25%) died or were discharged in a vegetative state (p = ns) (Table 1).

Hyperventilation was common after TBI. However, patients ventilated to a normal PaCO2 were significantly more acidotic. Prehospital personnel should undergo educational training after development of strict ventilation protocols for patients suffering TBI.