Choice A reason:

Choice A Reason:
Signing a release for laboratory results is a form of expressed consent, not implied consent. Expressed consent is given explicitly, either orally or in writing, and is clearly and unmistakably communicated. It involves a clear action of agreement to the specific procedure or intervention proposed.

Choice B Reason:
Signing a document of agreement for a research study is also an example of expressed consent. The patient is actively agreeing to participate in the study, which is a direct and informed action. This type of consent is necessary for research studies to ensure that participants are fully aware of the study's nature and any potential risks involved.

Choice C Reason:
Implied consent occurs when a patient's actions suggest consent without verbal or written confirmation. Offering an arm to a phlebotomist is a non-verbal communication that implies the patient is willing to have their blood drawn. This is a common practice in medical settings where the action of presenting an arm indicates readiness for the procedure.

Choice D Reason:
A family member nodding for a phlebotomist to proceed does not constitute the patient's implied consent. Consent must come directly from the patient unless they are unable to provide it, in which case a legal surrogate may give consent on their behalf. The nod of a family member cannot be assumed as the patient's consent.

Choice A Reason:
The recommended heel stick depth of 2.0 mm is based on the need to minimize the risk of injury to the infant. Penetrating deeper than this can increase the likelihood of hitting bone, which in infants can be as close as 2.0 mm under the skin of the plantar surface of the heel. This depth is sufficient to obtain a blood sample without risking injury to deeper tissues or bone.

Choice B Reason:
A depth of 2.5 mm may be too deep for some infants, especially preterm or very small infants, where the calcaneus (heel bone) is closer to the surface. While this depth might still be safe for some infants, it does not provide the same margin of safety as the 2.0 mm recommendation and could potentially lead to bone puncture or other injuries.

Choice C Reason:
A depth of 3.0 mm significantly increases the risk of bone puncture, especially in infants with less subcutaneous fat or in those who are preterm. This depth could easily breach the protective layer of skin and subcutaneous tissue, leading to a higher risk of osteomyelitis, an infection of the bone, which can be a serious complication in infants.

Choice D Reason:
A depth of 3.5 mm is considered too deep for a heel stick procedure and is likely to cause injury to the infant. This depth would almost certainly penetrate the bone in most infants, leading to severe pain, potential for infection, and other complications. It is well beyond the safe range recommended by CLSI and should be avoided.