Reflections on Blow-Tap-Talk (BTT), Recommendations for Resuscitation in Freediving Blackouts
Authors: (Uncredited / compiled document with medical contributions from Carl Willem, Pierre Michelet and others)
DOI / Source: n/a
Date: 2019
Reading level: Beginner
Why This Matters for Freedivers
If someone stops breathing after a blackout, the only thing that truly matters is restoring oxygen to the brain fast. This document explains why relying only on BTT can be risky in some scenarios, and why early rescue breaths (and oxygen) should be part of your safety toolbox—especially when you can’t be sure whether there was water inhalation or a more serious medical problem.
Synopsis
This document is a practical, safety-focused discussion about what to do when a freediver has a hypoxic blackout (or severe samba) and is not breathing. It reviews common freediving rescue practice—especially the Blow–Tap–Talk (BTT) method—and challenges some assumptions behind it.
The core issue is uncertainty. After a blackout, some freedivers may have a protective airway closure (often discussed as laryngospasm), but the document argues that the frequency and duration of this response in freediving is unknown and not reliably predictable. In other words: you can’t safely assume “the airway is sealed” or “no water entered.” It also highlights that blackouts can sometimes hide more serious events than “simple hypoxia,” such as lung squeeze/edema, pneumothorax, stroke-like events, decompression illness in repetitive deep diving, or other cardio-respiratory problems. Because you can’t diagnose that in the water, the document recommends a precautionary approach.
It describes three main scenarios: 1) Blackout at the surface after a severe samba: the diver may recover quickly if the airway is clear, so brief stimulation can help—but waiting too long wastes critical time if breathing doesn’t restart. 2) Blackout underwater with possible laryngospasm: rescue breaths may be difficult or ineffective during active airway closure, but that doesn’t remove the need to restore oxygen as soon as possible once the diver is secured. 3) Blackout underwater without laryngospasm and/or after exhalation: this is treated as true respiratory distress—meaning the diver is not just “paused,” but oxygen delivery is failing and ventilation should be restarted urgently.
A key theme is that many “BTT vs rescue breaths” arguments are built on conjecture rather than solid data. The document includes opinions from experienced hyperbaric/emergency physicians emphasizing that the brain is in acute hypoxemia during blackout, and that rapid re-oxygenation should be prioritized. It also addresses common fears (like rescue breaths “causing drowning” or vomiting) and argues that these risks are often overstated compared with the risk of delayed oxygenation.
Practical recommendations are split by context: - Club / normal training (limited medical support): use quick stimulation (BTT-style) but switch rapidly to rescue breaths and oxygen if there’s no immediate recovery. - Competition / high-performance settings (medical team present): prefer earlier rescue breaths after loss of consciousness, and transport to medical support as fast as possible.
Overall, it’s a “precautionary principle” document: don’t assume the blackout is benign, don’t assume the airway is protected, and don’t waste time when breathing hasn’t restarted.
Abstract
This document reviews and discusses rescue procedures for freediving-related loss of consciousness, focusing on the Blow–Tap–Talk (BTT) approach versus early rescue breaths. It argues that key assumptions often used to justify delaying ventilation—particularly the presence and duration of laryngospasm and the absence of water inhalation—are uncertain in freediving and not supported by definitive scientific evidence. Because freediving blackouts may involve respiratory distress and may be complicated by conditions such as lung injury, drowning, or other medical events, the document recommends a precautionary approach prioritizing rapid restoration of breathing and oxygenation. It proposes context-dependent recommendations: brief stimulation with rapid transition to rescue breaths and oxygen in club practice, and earlier preference for rescue breaths with rapid handover to medical teams in competition settings.